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qemu / qemu / 82d70a84c8ee42ef969a9cfddc0f5b30b16165f5 / . / block.c
blob: eac105a5041b6e5f299cf20d319a20dde034f1a4 [file] [log] [blame]
/*
* QEMU System Emulator block driver
*
* Copyright (c) 2003 Fabrice Bellard
* Copyright (c) 2020 Virtuozzo International GmbH.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include "block/trace.h"
#include "block/block_int.h"
#include "block/blockjob.h"
#include "block/dirty-bitmap.h"
#include "block/fuse.h"
#include "block/nbd.h"
#include "block/qdict.h"
#include "qemu/error-report.h"
#include "block/module_block.h"
#include "qemu/main-loop.h"
#include "qemu/module.h"
#include "qapi/error.h"
#include "qapi/qmp/qdict.h"
#include "qapi/qmp/qjson.h"
#include "qapi/qmp/qnull.h"
#include "qapi/qmp/qstring.h"
#include "qapi/qobject-output-visitor.h"
#include "qapi/qapi-visit-block-core.h"
#include "sysemu/block-backend.h"
#include "qemu/notify.h"
#include "qemu/option.h"
#include "qemu/coroutine.h"
#include "block/qapi.h"
#include "qemu/timer.h"
#include "qemu/cutils.h"
#include "qemu/id.h"
#include "qemu/range.h"
#include "qemu/rcu.h"
#include "block/coroutines.h"
#ifdef CONFIG_BSD
#include <sys/ioctl.h>
#include <sys/queue.h>
#if defined(HAVE_SYS_DISK_H)
#include <sys/disk.h>
#endif
#endif
#ifdef _WIN32
#include <windows.h>
#endif
#define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */
/* Protected by BQL */
static QTAILQ_HEAD(, BlockDriverState) graph_bdrv_states =
QTAILQ_HEAD_INITIALIZER(graph_bdrv_states);
/* Protected by BQL */
static QTAILQ_HEAD(, BlockDriverState) all_bdrv_states =
QTAILQ_HEAD_INITIALIZER(all_bdrv_states);
/* Protected by BQL */
static QLIST_HEAD(, BlockDriver) bdrv_drivers =
QLIST_HEAD_INITIALIZER(bdrv_drivers);
static BlockDriverState *bdrv_open_inherit(const char *filename,
const char *reference,
QDict *options, int flags,
BlockDriverState *parent,
const BdrvChildClass *child_class,
BdrvChildRole child_role,
Error **errp);
static bool bdrv_recurse_has_child(BlockDriverState *bs,
BlockDriverState *child);
static void GRAPH_WRLOCK
bdrv_replace_child_noperm(BdrvChild *child, BlockDriverState *new_bs);
static void GRAPH_WRLOCK
bdrv_remove_child(BdrvChild *child, Transaction *tran);
static int bdrv_reopen_prepare(BDRVReopenState *reopen_state,
BlockReopenQueue *queue,
Transaction *change_child_tran, Error **errp);
static void bdrv_reopen_commit(BDRVReopenState *reopen_state);
static void bdrv_reopen_abort(BDRVReopenState *reopen_state);
static bool bdrv_backing_overridden(BlockDriverState *bs);
static bool bdrv_change_aio_context(BlockDriverState *bs, AioContext *ctx,
GHashTable *visited, Transaction *tran,
Error **errp);
/* If non-zero, use only whitelisted block drivers */
static int use_bdrv_whitelist;
#ifdef _WIN32
static int is_windows_drive_prefix(const char *filename)
{
return (((filename[0] >= 'a' && filename[0] <= 'z') ||
(filename[0] >= 'A' && filename[0] <= 'Z')) &&
filename[1] == ':');
}
int is_windows_drive(const char *filename)
{
if (is_windows_drive_prefix(filename) &&
filename[2] == '\0')
return 1;
if (strstart(filename, "\\\\.\\", NULL) ||
strstart(filename, "//./", NULL))
return 1;
return 0;
}
#endif
size_t bdrv_opt_mem_align(BlockDriverState *bs)
{
if (!bs || !bs->drv) {
/* page size or 4k (hdd sector size) should be on the safe side */
return MAX(4096, qemu_real_host_page_size());
}
IO_CODE();
return bs->bl.opt_mem_alignment;
}
size_t bdrv_min_mem_align(BlockDriverState *bs)
{
if (!bs || !bs->drv) {
/* page size or 4k (hdd sector size) should be on the safe side */
return MAX(4096, qemu_real_host_page_size());
}
IO_CODE();
return bs->bl.min_mem_alignment;
}
/* check if the path starts with "<protocol>:" */
int path_has_protocol(const char *path)
{
const char *p;
#ifdef _WIN32
if (is_windows_drive(path) ||
is_windows_drive_prefix(path)) {
return 0;
}
p = path + strcspn(path, ":/\\");
#else
p = path + strcspn(path, ":/");
#endif
return *p == ':';
}
int path_is_absolute(const char *path)
{
#ifdef _WIN32
/* specific case for names like: "\\.\d:" */
if (is_windows_drive(path) || is_windows_drive_prefix(path)) {
return 1;
}
return (*path == '/' || *path == '\\');
#else
return (*path == '/');
#endif
}
/* if filename is absolute, just return its duplicate. Otherwise, build a
path to it by considering it is relative to base_path. URL are
supported. */
char *path_combine(const char *base_path, const char *filename)
{
const char *protocol_stripped = NULL;
const char *p, *p1;
char *result;
int len;
if (path_is_absolute(filename)) {
return g_strdup(filename);
}
if (path_has_protocol(base_path)) {
protocol_stripped = strchr(base_path, ':');
if (protocol_stripped) {
protocol_stripped++;
}
}
p = protocol_stripped ?: base_path;
p1 = strrchr(base_path, '/');
#ifdef _WIN32
{
const char *p2;
p2 = strrchr(base_path, '\\');
if (!p1 || p2 > p1) {
p1 = p2;
}
}
#endif
if (p1) {
p1++;
} else {
p1 = base_path;
}
if (p1 > p) {
p = p1;
}
len = p - base_path;
result = g_malloc(len + strlen(filename) + 1);
memcpy(result, base_path, len);
strcpy(result + len, filename);
return result;
}
/*
* Helper function for bdrv_parse_filename() implementations to remove optional
* protocol prefixes (especially "file:") from a filename and for putting the
* stripped filename into the options QDict if there is such a prefix.
*/
void bdrv_parse_filename_strip_prefix(const char *filename, const char *prefix,
QDict *options)
{
if (strstart(filename, prefix, &filename)) {
/* Stripping the explicit protocol prefix may result in a protocol
* prefix being (wrongly) detected (if the filename contains a colon) */
if (path_has_protocol(filename)) {
GString *fat_filename;
/* This means there is some colon before the first slash; therefore,
* this cannot be an absolute path */
assert(!path_is_absolute(filename));
/* And we can thus fix the protocol detection issue by prefixing it
* by "./" */
fat_filename = g_string_new("./");
g_string_append(fat_filename, filename);
assert(!path_has_protocol(fat_filename->str));
qdict_put(options, "filename",
qstring_from_gstring(fat_filename));
} else {
/* If no protocol prefix was detected, we can use the shortened
* filename as-is */
qdict_put_str(options, "filename", filename);
}
}
}
/* Returns whether the image file is opened as read-only. Note that this can
* return false and writing to the image file is still not possible because the
* image is inactivated. */
bool bdrv_is_read_only(BlockDriverState *bs)
{
IO_CODE();
return !(bs->open_flags & BDRV_O_RDWR);
}
static int GRAPH_RDLOCK
bdrv_can_set_read_only(BlockDriverState *bs, bool read_only,
bool ignore_allow_rdw, Error **errp)
{
IO_CODE();
/* Do not set read_only if copy_on_read is enabled */
if (bs->copy_on_read && read_only) {
error_setg(errp, "Can't set node '%s' to r/o with copy-on-read enabled",
bdrv_get_device_or_node_name(bs));
return -EINVAL;
}
/* Do not clear read_only if it is prohibited */
if (!read_only && !(bs->open_flags & BDRV_O_ALLOW_RDWR) &&
!ignore_allow_rdw)
{
error_setg(errp, "Node '%s' is read only",
bdrv_get_device_or_node_name(bs));
return -EPERM;
}
return 0;
}
/*
* Called by a driver that can only provide a read-only image.
*
* Returns 0 if the node is already read-only or it could switch the node to
* read-only because BDRV_O_AUTO_RDONLY is set.
*
* Returns -EACCES if the node is read-write and BDRV_O_AUTO_RDONLY is not set
* or bdrv_can_set_read_only() forbids making the node read-only. If @errmsg
* is not NULL, it is used as the error message for the Error object.
*/
int bdrv_apply_auto_read_only(BlockDriverState *bs, const char *errmsg,
Error **errp)
{
int ret = 0;
IO_CODE();
if (!(bs->open_flags & BDRV_O_RDWR)) {
return 0;
}
if (!(bs->open_flags & BDRV_O_AUTO_RDONLY)) {
goto fail;
}
ret = bdrv_can_set_read_only(bs, true, false, NULL);
if (ret < 0) {
goto fail;
}
bs->open_flags &= ~BDRV_O_RDWR;
return 0;
fail:
error_setg(errp, "%s", errmsg ?: "Image is read-only");
return -EACCES;
}
/*
* If @backing is empty, this function returns NULL without setting
* @errp. In all other cases, NULL will only be returned with @errp
* set.
*
* Therefore, a return value of NULL without @errp set means that
* there is no backing file; if @errp is set, there is one but its
* absolute filename cannot be generated.
*/
char *bdrv_get_full_backing_filename_from_filename(const char *backed,
const char *backing,
Error **errp)
{
if (backing[0] == '\0') {
return NULL;
} else if (path_has_protocol(backing) || path_is_absolute(backing)) {
return g_strdup(backing);
} else if (backed[0] == '\0' || strstart(backed, "json:", NULL)) {
error_setg(errp, "Cannot use relative backing file names for '%s'",
backed);
return NULL;
} else {
return path_combine(backed, backing);
}
}
/*
* If @filename is empty or NULL, this function returns NULL without
* setting @errp. In all other cases, NULL will only be returned with
* @errp set.
*/
static char * GRAPH_RDLOCK
bdrv_make_absolute_filename(BlockDriverState *relative_to,
const char *filename, Error **errp)
{
char *dir, *full_name;
if (!filename || filename[0] == '\0') {
return NULL;
} else if (path_has_protocol(filename) || path_is_absolute(filename)) {
return g_strdup(filename);
}
dir = bdrv_dirname(relative_to, errp);
if (!dir) {
return NULL;
}
full_name = g_strconcat(dir, filename, NULL);
g_free(dir);
return full_name;
}
char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp)
{
GLOBAL_STATE_CODE();
return bdrv_make_absolute_filename(bs, bs->backing_file, errp);
}
void bdrv_register(BlockDriver *bdrv)
{
assert(bdrv->format_name);
GLOBAL_STATE_CODE();
QLIST_INSERT_HEAD(&bdrv_drivers, bdrv, list);
}
BlockDriverState *bdrv_new(void)
{
BlockDriverState *bs;
int i;
GLOBAL_STATE_CODE();
bs = g_new0(BlockDriverState, 1);
QLIST_INIT(&bs->dirty_bitmaps);
for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
QLIST_INIT(&bs->op_blockers[i]);
}
qemu_mutex_init(&bs->reqs_lock);
qemu_mutex_init(&bs->dirty_bitmap_mutex);
bs->refcnt = 1;
bs->aio_context = qemu_get_aio_context();
qemu_co_queue_init(&bs->flush_queue);
qemu_co_mutex_init(&bs->bsc_modify_lock);
bs->block_status_cache = g_new0(BdrvBlockStatusCache, 1);
for (i = 0; i < bdrv_drain_all_count; i++) {
bdrv_drained_begin(bs);
}
QTAILQ_INSERT_TAIL(&all_bdrv_states, bs, bs_list);
return bs;
}
static BlockDriver *bdrv_do_find_format(const char *format_name)
{
BlockDriver *drv1;
GLOBAL_STATE_CODE();
QLIST_FOREACH(drv1, &bdrv_drivers, list) {
if (!strcmp(drv1->format_name, format_name)) {
return drv1;
}
}
return NULL;
}
BlockDriver *bdrv_find_format(const char *format_name)
{
BlockDriver *drv1;
int i;
GLOBAL_STATE_CODE();
drv1 = bdrv_do_find_format(format_name);
if (drv1) {
return drv1;
}
/* The driver isn't registered, maybe we need to load a module */
for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) {
if (!strcmp(block_driver_modules[i].format_name, format_name)) {
Error *local_err = NULL;
int rv = block_module_load(block_driver_modules[i].library_name,
&local_err);
if (rv > 0) {
return bdrv_do_find_format(format_name);
} else if (rv < 0) {
error_report_err(local_err);
}
break;
}
}
return NULL;
}
static int bdrv_format_is_whitelisted(const char *format_name, bool read_only)
{
static const char *whitelist_rw[] = {
CONFIG_BDRV_RW_WHITELIST
NULL
};
static const char *whitelist_ro[] = {
CONFIG_BDRV_RO_WHITELIST
NULL
};
const char **p;
if (!whitelist_rw[0] && !whitelist_ro[0]) {
return 1; /* no whitelist, anything goes */
}
for (p = whitelist_rw; *p; p++) {
if (!strcmp(format_name, *p)) {
return 1;
}
}
if (read_only) {
for (p = whitelist_ro; *p; p++) {
if (!strcmp(format_name, *p)) {
return 1;
}
}
}
return 0;
}
int bdrv_is_whitelisted(BlockDriver *drv, bool read_only)
{
GLOBAL_STATE_CODE();
return bdrv_format_is_whitelisted(drv->format_name, read_only);
}
bool bdrv_uses_whitelist(void)
{
return use_bdrv_whitelist;
}
typedef struct CreateCo {
BlockDriver *drv;
char *filename;
QemuOpts *opts;
int ret;
Error *err;
} CreateCo;
int coroutine_fn bdrv_co_create(BlockDriver *drv, const char *filename,
QemuOpts *opts, Error **errp)
{
int ret;
GLOBAL_STATE_CODE();
ERRP_GUARD();
if (!drv->bdrv_co_create_opts) {
error_setg(errp, "Driver '%s' does not support image creation",
drv->format_name);
return -ENOTSUP;
}
ret = drv->bdrv_co_create_opts(drv, filename, opts, errp);
if (ret < 0 && !*errp) {
error_setg_errno(errp, -ret, "Could not create image");
}
return ret;
}
/**
* Helper function for bdrv_create_file_fallback(): Resize @blk to at
* least the given @minimum_size.
*
* On success, return @blk's actual length.
* Otherwise, return -errno.
*/
static int64_t coroutine_fn GRAPH_UNLOCKED
create_file_fallback_truncate(BlockBackend *blk, int64_t minimum_size,
Error **errp)
{
Error *local_err = NULL;
int64_t size;
int ret;
GLOBAL_STATE_CODE();
ret = blk_co_truncate(blk, minimum_size, false, PREALLOC_MODE_OFF, 0,
&local_err);
if (ret < 0 && ret != -ENOTSUP) {
error_propagate(errp, local_err);
return ret;
}
size = blk_co_getlength(blk);
if (size < 0) {
error_free(local_err);
error_setg_errno(errp, -size,
"Failed to inquire the new image file's length");
return size;
}
if (size < minimum_size) {
/* Need to grow the image, but we failed to do that */
error_propagate(errp, local_err);
return -ENOTSUP;
}
error_free(local_err);
local_err = NULL;
return size;
}
/**
* Helper function for bdrv_create_file_fallback(): Zero the first
* sector to remove any potentially pre-existing image header.
*/
static int coroutine_fn
create_file_fallback_zero_first_sector(BlockBackend *blk,
int64_t current_size,
Error **errp)
{
int64_t bytes_to_clear;
int ret;
GLOBAL_STATE_CODE();
bytes_to_clear = MIN(current_size, BDRV_SECTOR_SIZE);
if (bytes_to_clear) {
ret = blk_co_pwrite_zeroes(blk, 0, bytes_to_clear, BDRV_REQ_MAY_UNMAP);
if (ret < 0) {
error_setg_errno(errp, -ret,
"Failed to clear the new image's first sector");
return ret;
}
}
return 0;
}
/**
* Simple implementation of bdrv_co_create_opts for protocol drivers
* which only support creation via opening a file
* (usually existing raw storage device)
*/
int coroutine_fn bdrv_co_create_opts_simple(BlockDriver *drv,
const char *filename,
QemuOpts *opts,
Error **errp)
{
BlockBackend *blk;
QDict *options;
int64_t size = 0;
char *buf = NULL;
PreallocMode prealloc;
Error *local_err = NULL;
int ret;
GLOBAL_STATE_CODE();
size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0);
buf = qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC);
prealloc = qapi_enum_parse(&PreallocMode_lookup, buf,
PREALLOC_MODE_OFF, &local_err);
g_free(buf);
if (local_err) {
error_propagate(errp, local_err);
return -EINVAL;
}
if (prealloc != PREALLOC_MODE_OFF) {
error_setg(errp, "Unsupported preallocation mode '%s'",
PreallocMode_str(prealloc));
return -ENOTSUP;
}
options = qdict_new();
qdict_put_str(options, "driver", drv->format_name);
blk = blk_co_new_open(filename, NULL, options,
BDRV_O_RDWR | BDRV_O_RESIZE, errp);
if (!blk) {
error_prepend(errp, "Protocol driver '%s' does not support creating "
"new images, so an existing image must be selected as "
"the target; however, opening the given target as an "
"existing image failed: ",
drv->format_name);
return -EINVAL;
}
size = create_file_fallback_truncate(blk, size, errp);
if (size < 0) {
ret = size;
goto out;
}
ret = create_file_fallback_zero_first_sector(blk, size, errp);
if (ret < 0) {
goto out;
}
ret = 0;
out:
blk_co_unref(blk);
return ret;
}
int coroutine_fn bdrv_co_create_file(const char *filename, QemuOpts *opts,
Error **errp)
{
QemuOpts *protocol_opts;
BlockDriver *drv;
QDict *qdict;
int ret;
GLOBAL_STATE_CODE();
drv = bdrv_find_protocol(filename, true, errp);
if (drv == NULL) {
return -ENOENT;
}
if (!drv->create_opts) {
error_setg(errp, "Driver '%s' does not support image creation",
drv->format_name);
return -ENOTSUP;
}
/*
* 'opts' contains a QemuOptsList with a combination of format and protocol
* default values.
*
* The format properly removes its options, but the default values remain
* in 'opts->list'. So if the protocol has options with the same name
* (e.g. rbd has 'cluster_size' as qcow2), it will see the default values
* of the format, since for overlapping options, the format wins.
*
* To avoid this issue, lets convert QemuOpts to QDict, in this way we take
* only the set options, and then convert it back to QemuOpts, using the
* create_opts of the protocol. So the new QemuOpts, will contain only the
* protocol defaults.
*/
qdict = qemu_opts_to_qdict(opts, NULL);
protocol_opts = qemu_opts_from_qdict(drv->create_opts, qdict, errp);
if (protocol_opts == NULL) {
ret = -EINVAL;
goto out;
}
ret = bdrv_co_create(drv, filename, protocol_opts, errp);
out:
qemu_opts_del(protocol_opts);
qobject_unref(qdict);
return ret;
}
int coroutine_fn bdrv_co_delete_file(BlockDriverState *bs, Error **errp)
{
Error *local_err = NULL;
int ret;
IO_CODE();
assert(bs != NULL);
assert_bdrv_graph_readable();
if (!bs->drv) {
error_setg(errp, "Block node '%s' is not opened", bs->filename);
return -ENOMEDIUM;
}
if (!bs->drv->bdrv_co_delete_file) {
error_setg(errp, "Driver '%s' does not support image deletion",
bs->drv->format_name);
return -ENOTSUP;
}
ret = bs->drv->bdrv_co_delete_file(bs, &local_err);
if (ret < 0) {
error_propagate(errp, local_err);
}
return ret;
}
void coroutine_fn bdrv_co_delete_file_noerr(BlockDriverState *bs)
{
Error *local_err = NULL;
int ret;
IO_CODE();
if (!bs) {
return;
}
ret = bdrv_co_delete_file(bs, &local_err);
/*
* ENOTSUP will happen if the block driver doesn't support
* the 'bdrv_co_delete_file' interface. This is a predictable
* scenario and shouldn't be reported back to the user.
*/
if (ret == -ENOTSUP) {
error_free(local_err);
} else if (ret < 0) {
error_report_err(local_err);
}
}
/**
* Try to get @bs's logical and physical block size.
* On success, store them in @bsz struct and return 0.
* On failure return -errno.
* @bs must not be empty.
*/
int bdrv_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz)
{
BlockDriver *drv = bs->drv;
BlockDriverState *filtered = bdrv_filter_bs(bs);
GLOBAL_STATE_CODE();
if (drv && drv->bdrv_probe_blocksizes) {
return drv->bdrv_probe_blocksizes(bs, bsz);
} else if (filtered) {
return bdrv_probe_blocksizes(filtered, bsz);
}
return -ENOTSUP;
}
/**
* Try to get @bs's geometry (cyls, heads, sectors).
* On success, store them in @geo struct and return 0.
* On failure return -errno.
* @bs must not be empty.
*/
int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry *geo)
{
BlockDriver *drv = bs->drv;
BlockDriverState *filtered;
GLOBAL_STATE_CODE();
GRAPH_RDLOCK_GUARD_MAINLOOP();
if (drv && drv->bdrv_probe_geometry) {
return drv->bdrv_probe_geometry(bs, geo);
}
filtered = bdrv_filter_bs(bs);
if (filtered) {
return bdrv_probe_geometry(filtered, geo);
}
return -ENOTSUP;
}
/*
* Create a uniquely-named empty temporary file.
* Return the actual file name used upon success, otherwise NULL.
* This string should be freed with g_free() when not needed any longer.
*
* Note: creating a temporary file for the caller to (re)open is
* inherently racy. Use g_file_open_tmp() instead whenever practical.
*/
char *create_tmp_file(Error **errp)
{
int fd;
const char *tmpdir;
g_autofree char *filename = NULL;
tmpdir = g_get_tmp_dir();
#ifndef _WIN32
/*
* See commit 69bef79 ("block: use /var/tmp instead of /tmp for -snapshot")
*
* This function is used to create temporary disk images (like -snapshot),
* so the files can become very large. /tmp is often a tmpfs where as
* /var/tmp is usually on a disk, so more appropriate for disk images.
*/
if (!g_strcmp0(tmpdir, "/tmp")) {
tmpdir = "/var/tmp";
}
#endif
filename = g_strdup_printf("%s/vl.XXXXXX", tmpdir);
fd = g_mkstemp(filename);
if (fd < 0) {
error_setg_errno(errp, errno, "Could not open temporary file '%s'",
filename);
return NULL;
}
close(fd);
return g_steal_pointer(&filename);
}
/*
* Detect host devices. By convention, /dev/cdrom[N] is always
* recognized as a host CDROM.
*/
static BlockDriver *find_hdev_driver(const char *filename)
{
int score_max = 0, score;
BlockDriver *drv = NULL, *d;
GLOBAL_STATE_CODE();
QLIST_FOREACH(d, &bdrv_drivers, list) {
if (d->bdrv_probe_device) {
score = d->bdrv_probe_device(filename);
if (score > score_max) {
score_max = score;
drv = d;
}
}
}
return drv;
}
static BlockDriver *bdrv_do_find_protocol(const char *protocol)
{
BlockDriver *drv1;
GLOBAL_STATE_CODE();
QLIST_FOREACH(drv1, &bdrv_drivers, list) {
if (drv1->protocol_name && !strcmp(drv1->protocol_name, protocol)) {
return drv1;
}
}
return NULL;
}
BlockDriver *bdrv_find_protocol(const char *filename,
bool allow_protocol_prefix,
Error **errp)
{
BlockDriver *drv1;
char protocol[128];
int len;
const char *p;
int i;
GLOBAL_STATE_CODE();
/* TODO Drivers without bdrv_file_open must be specified explicitly */
/*
* XXX(hch): we really should not let host device detection
* override an explicit protocol specification, but moving this
* later breaks access to device names with colons in them.
* Thanks to the brain-dead persistent naming schemes on udev-
* based Linux systems those actually are quite common.
*/
drv1 = find_hdev_driver(filename);
if (drv1) {
return drv1;
}
if (!path_has_protocol(filename) || !allow_protocol_prefix) {
return &bdrv_file;
}
p = strchr(filename, ':');
assert(p != NULL);
len = p - filename;
if (len > sizeof(protocol) - 1)
len = sizeof(protocol) - 1;
memcpy(protocol, filename, len);
protocol[len] = '\0';
drv1 = bdrv_do_find_protocol(protocol);
if (drv1) {
return drv1;
}
for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) {
if (block_driver_modules[i].protocol_name &&
!strcmp(block_driver_modules[i].protocol_name, protocol)) {
int rv = block_module_load(block_driver_modules[i].library_name, errp);
if (rv > 0) {
drv1 = bdrv_do_find_protocol(protocol);
} else if (rv < 0) {
return NULL;
}
break;
}
}
if (!drv1) {
error_setg(errp, "Unknown protocol '%s'", protocol);
}
return drv1;
}
/*
* Guess image format by probing its contents.
* This is not a good idea when your image is raw (CVE-2008-2004), but
* we do it anyway for backward compatibility.
*
* @buf contains the image's first @buf_size bytes.
* @buf_size is the buffer size in bytes (generally BLOCK_PROBE_BUF_SIZE,
* but can be smaller if the image file is smaller)
* @filename is its filename.
*
* For all block drivers, call the bdrv_probe() method to get its
* probing score.
* Return the first block driver with the highest probing score.
*/
BlockDriver *bdrv_probe_all(const uint8_t *buf, int buf_size,
const char *filename)
{
int score_max = 0, score;
BlockDriver *drv = NULL, *d;
IO_CODE();
QLIST_FOREACH(d, &bdrv_drivers, list) {
if (d->bdrv_probe) {
score = d->bdrv_probe(buf, buf_size, filename);
if (score > score_max) {
score_max = score;
drv = d;
}
}
}
return drv;
}
static int find_image_format(BlockBackend *file, const char *filename,
BlockDriver **pdrv, Error **errp)
{
BlockDriver *drv;
uint8_t buf[BLOCK_PROBE_BUF_SIZE];
int ret = 0;
GLOBAL_STATE_CODE();
/* Return the raw BlockDriver * to scsi-generic devices or empty drives */
if (blk_is_sg(file) || !blk_is_inserted(file) || blk_getlength(file) == 0) {
*pdrv = &bdrv_raw;
return ret;
}
ret = blk_pread(file, 0, sizeof(buf), buf, 0);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not read image for determining its "
"format");
*pdrv = NULL;
return ret;
}
drv = bdrv_probe_all(buf, sizeof(buf), filename);
if (!drv) {
error_setg(errp, "Could not determine image format: No compatible "
"driver found");
*pdrv = NULL;
return -ENOENT;
}
*pdrv = drv;
return 0;
}
/**
* Set the current 'total_sectors' value
* Return 0 on success, -errno on error.
*/
int coroutine_fn bdrv_co_refresh_total_sectors(BlockDriverState *bs,
int64_t hint)
{
BlockDriver *drv = bs->drv;
IO_CODE();
assert_bdrv_graph_readable();
if (!drv) {
return -ENOMEDIUM;
}
/* Do not attempt drv->bdrv_co_getlength() on scsi-generic devices */
if (bdrv_is_sg(bs))
return 0;
/* query actual device if possible, otherwise just trust the hint */
if (drv->bdrv_co_getlength) {
int64_t length = drv->bdrv_co_getlength(bs);
if (length < 0) {
return length;
}
hint = DIV_ROUND_UP(length, BDRV_SECTOR_SIZE);
}
bs->total_sectors = hint;
if (bs->total_sectors * BDRV_SECTOR_SIZE > BDRV_MAX_LENGTH) {
return -EFBIG;
}
return 0;
}
/**
* Combines a QDict of new block driver @options with any missing options taken
* from @old_options, so that leaving out an option defaults to its old value.
*/
static void bdrv_join_options(BlockDriverState *bs, QDict *options,
QDict *old_options)
{
GLOBAL_STATE_CODE();
if (bs->drv && bs->drv->bdrv_join_options) {
bs->drv->bdrv_join_options(options, old_options);
} else {
qdict_join(options, old_options, false);
}
}
static BlockdevDetectZeroesOptions bdrv_parse_detect_zeroes(QemuOpts *opts,
int open_flags,
Error **errp)
{
Error *local_err = NULL;
char *value = qemu_opt_get_del(opts, "detect-zeroes");
BlockdevDetectZeroesOptions detect_zeroes =
qapi_enum_parse(&BlockdevDetectZeroesOptions_lookup, value,
BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF, &local_err);
GLOBAL_STATE_CODE();
g_free(value);
if (local_err) {
error_propagate(errp, local_err);
return detect_zeroes;
}
if (detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP &&
!(open_flags & BDRV_O_UNMAP))
{
error_setg(errp, "setting detect-zeroes to unmap is not allowed "
"without setting discard operation to unmap");
}
return detect_zeroes;
}
/**
* Set open flags for aio engine
*
* Return 0 on success, -1 if the engine specified is invalid
*/
int bdrv_parse_aio(const char *mode, int *flags)
{
if (!strcmp(mode, "threads")) {
/* do nothing, default */
} else if (!strcmp(mode, "native")) {
*flags |= BDRV_O_NATIVE_AIO;
#ifdef CONFIG_LINUX_IO_URING
} else if (!strcmp(mode, "io_uring")) {
*flags |= BDRV_O_IO_URING;
#endif
} else {
return -1;
}
return 0;
}
/**
* Set open flags for a given discard mode
*
* Return 0 on success, -1 if the discard mode was invalid.
*/
int bdrv_parse_discard_flags(const char *mode, int *flags)
{
*flags &= ~BDRV_O_UNMAP;
if (!strcmp(mode, "off") || !strcmp(mode, "ignore")) {
/* do nothing */
} else if (!strcmp(mode, "on") || !strcmp(mode, "unmap")) {
*flags |= BDRV_O_UNMAP;
} else {
return -1;
}
return 0;
}
/**
* Set open flags for a given cache mode
*
* Return 0 on success, -1 if the cache mode was invalid.
*/
int bdrv_parse_cache_mode(const char *mode, int *flags, bool *writethrough)
{
*flags &= ~BDRV_O_CACHE_MASK;
if (!strcmp(mode, "off") || !strcmp(mode, "none")) {
*writethrough = false;
*flags |= BDRV_O_NOCACHE;
} else if (!strcmp(mode, "directsync")) {
*writethrough = true;
*flags |= BDRV_O_NOCACHE;
} else if (!strcmp(mode, "writeback")) {
*writethrough = false;
} else if (!strcmp(mode, "unsafe")) {
*writethrough = false;
*flags |= BDRV_O_NO_FLUSH;
} else if (!strcmp(mode, "writethrough")) {
*writethrough = true;
} else {
return -1;
}
return 0;
}
static char *bdrv_child_get_parent_desc(BdrvChild *c)
{
BlockDriverState *parent = c->opaque;
return g_strdup_printf("node '%s'", bdrv_get_node_name(parent));
}
static void GRAPH_RDLOCK bdrv_child_cb_drained_begin(BdrvChild *child)
{
BlockDriverState *bs = child->opaque;
bdrv_do_drained_begin_quiesce(bs, NULL);
}
static bool GRAPH_RDLOCK bdrv_child_cb_drained_poll(BdrvChild *child)
{
BlockDriverState *bs = child->opaque;
return bdrv_drain_poll(bs, NULL, false);
}
static void GRAPH_RDLOCK bdrv_child_cb_drained_end(BdrvChild *child)
{
BlockDriverState *bs = child->opaque;
bdrv_drained_end(bs);
}
static int bdrv_child_cb_inactivate(BdrvChild *child)
{
BlockDriverState *bs = child->opaque;
GLOBAL_STATE_CODE();
assert(bs->open_flags & BDRV_O_INACTIVE);
return 0;
}
static bool bdrv_child_cb_change_aio_ctx(BdrvChild *child, AioContext *ctx,
GHashTable *visited, Transaction *tran,
Error **errp)
{
BlockDriverState *bs = child->opaque;
return bdrv_change_aio_context(bs, ctx, visited, tran, errp);
}
/*
* Returns the options and flags that a temporary snapshot should get, based on
* the originally requested flags (the originally requested image will have
* flags like a backing file)
*/
static void bdrv_temp_snapshot_options(int *child_flags, QDict *child_options,
int parent_flags, QDict *parent_options)
{
GLOBAL_STATE_CODE();
*child_flags = (parent_flags & ~BDRV_O_SNAPSHOT) | BDRV_O_TEMPORARY;
/* For temporary files, unconditional cache=unsafe is fine */
qdict_set_default_str(child_options, BDRV_OPT_CACHE_DIRECT, "off");
qdict_set_default_str(child_options, BDRV_OPT_CACHE_NO_FLUSH, "on");
/* Copy the read-only and discard options from the parent */
qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY);
qdict_copy_default(child_options, parent_options, BDRV_OPT_DISCARD);
/* aio=native doesn't work for cache.direct=off, so disable it for the
* temporary snapshot */
*child_flags &= ~BDRV_O_NATIVE_AIO;
}
static void GRAPH_WRLOCK bdrv_backing_attach(BdrvChild *c)
{
BlockDriverState *parent = c->opaque;
BlockDriverState *backing_hd = c->bs;
GLOBAL_STATE_CODE();
assert(!parent->backing_blocker);
error_setg(&parent->backing_blocker,
"node is used as backing hd of '%s'",
bdrv_get_device_or_node_name(parent));
bdrv_refresh_filename(backing_hd);
parent->open_flags &= ~BDRV_O_NO_BACKING;
bdrv_op_block_all(backing_hd, parent->backing_blocker);
/* Otherwise we won't be able to commit or stream */
bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_COMMIT_TARGET,
parent->backing_blocker);
bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_STREAM,
parent->backing_blocker);
/*
* We do backup in 3 ways:
* 1. drive backup
* The target bs is new opened, and the source is top BDS
* 2. blockdev backup
* Both the source and the target are top BDSes.
* 3. internal backup(used for block replication)
* Both the source and the target are backing file
*
* In case 1 and 2, neither the source nor the target is the backing file.
* In case 3, we will block the top BDS, so there is only one block job
* for the top BDS and its backing chain.
*/
bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_SOURCE,
parent->backing_blocker);
bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_TARGET,
parent->backing_blocker);
}
static void bdrv_backing_detach(BdrvChild *c)
{
BlockDriverState *parent = c->opaque;
GLOBAL_STATE_CODE();
assert(parent->backing_blocker);
bdrv_op_unblock_all(c->bs, parent->backing_blocker);
error_free(parent->backing_blocker);
parent->backing_blocker = NULL;
}
static int bdrv_backing_update_filename(BdrvChild *c, BlockDriverState *base,
const char *filename, Error **errp)
{
BlockDriverState *parent = c->opaque;
bool read_only = bdrv_is_read_only(parent);
int ret;
GLOBAL_STATE_CODE();
if (read_only) {
ret = bdrv_reopen_set_read_only(parent, false, errp);
if (ret < 0) {
return ret;
}
}
ret = bdrv_change_backing_file(parent, filename,
base->drv ? base->drv->format_name : "",
false);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not update backing file link");
}
if (read_only) {
bdrv_reopen_set_read_only(parent, true, NULL);
}
return ret;
}
/*
* Returns the options and flags that a generic child of a BDS should
* get, based on the given options and flags for the parent BDS.
*/
static void bdrv_inherited_options(BdrvChildRole role, bool parent_is_format,
int *child_flags, QDict *child_options,
int parent_flags, QDict *parent_options)
{
int flags = parent_flags;
GLOBAL_STATE_CODE();
/*
* First, decide whether to set, clear, or leave BDRV_O_PROTOCOL.
* Generally, the question to answer is: Should this child be
* format-probed by default?
*/
/*
* Pure and non-filtered data children of non-format nodes should
* be probed by default (even when the node itself has BDRV_O_PROTOCOL
* set). This only affects a very limited set of drivers (namely
* quorum and blkverify when this comment was written).
* Force-clear BDRV_O_PROTOCOL then.
*/
if (!parent_is_format &&
(role & BDRV_CHILD_DATA) &&
!(role & (BDRV_CHILD_METADATA | BDRV_CHILD_FILTERED)))
{
flags &= ~BDRV_O_PROTOCOL;
}
/*
* All children of format nodes (except for COW children) and all
* metadata children in general should never be format-probed.
* Force-set BDRV_O_PROTOCOL then.
*/
if ((parent_is_format && !(role & BDRV_CHILD_COW)) ||
(role & BDRV_CHILD_METADATA))
{
flags |= BDRV_O_PROTOCOL;
}
/*
* If the cache mode isn't explicitly set, inherit direct and no-flush from
* the parent.
*/
qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT);
qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH);
qdict_copy_default(child_options, parent_options, BDRV_OPT_FORCE_SHARE);
if (role & BDRV_CHILD_COW) {
/* backing files are opened read-only by default */
qdict_set_default_str(child_options, BDRV_OPT_READ_ONLY, "on");
qdict_set_default_str(child_options, BDRV_OPT_AUTO_READ_ONLY, "off");
} else {
/* Inherit the read-only option from the parent if it's not set */
qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY);
qdict_copy_default(child_options, parent_options,
BDRV_OPT_AUTO_READ_ONLY);
}
/*
* bdrv_co_pdiscard() respects unmap policy for the parent, so we
* can default to enable it on lower layers regardless of the
* parent option.
*/
qdict_set_default_str(child_options, BDRV_OPT_DISCARD, "unmap");
/* Clear flags that only apply to the top layer */
flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_COPY_ON_READ);
if (role & BDRV_CHILD_METADATA) {
flags &= ~BDRV_O_NO_IO;
}
if (role & BDRV_CHILD_COW) {
flags &= ~BDRV_O_TEMPORARY;
}
*child_flags = flags;
}
static void GRAPH_WRLOCK bdrv_child_cb_attach(BdrvChild *child)
{
BlockDriverState *bs = child->opaque;
assert_bdrv_graph_writable();
QLIST_INSERT_HEAD(&bs->children, child, next);
if (bs->drv->is_filter || (child->role & BDRV_CHILD_FILTERED)) {
/*
* Here we handle filters and block/raw-format.c when it behave like
* filter. They generally have a single PRIMARY child, which is also the
* FILTERED child, and that they may have multiple more children, which
* are neither PRIMARY nor FILTERED. And never we have a COW child here.
* So bs->file will be the PRIMARY child, unless the PRIMARY child goes
* into bs->backing on exceptional cases; and bs->backing will be
* nothing else.
*/
assert(!(child->role & BDRV_CHILD_COW));
if (child->role & BDRV_CHILD_PRIMARY) {
assert(child->role & BDRV_CHILD_FILTERED);
assert(!bs->backing);
assert(!bs->file);
if (bs->drv->filtered_child_is_backing) {
bs->backing = child;
} else {
bs->file = child;
}
} else {
assert(!(child->role & BDRV_CHILD_FILTERED));
}
} else if (child->role & BDRV_CHILD_COW) {
assert(bs->drv->supports_backing);
assert(!(child->role & BDRV_CHILD_PRIMARY));
assert(!bs->backing);
bs->backing = child;
bdrv_backing_attach(child);
} else if (child->role & BDRV_CHILD_PRIMARY) {
assert(!bs->file);
bs->file = child;
}
}
static void GRAPH_WRLOCK bdrv_child_cb_detach(BdrvChild *child)
{
BlockDriverState *bs = child->opaque;
if (child->role & BDRV_CHILD_COW) {
bdrv_backing_detach(child);
}
assert_bdrv_graph_writable();
QLIST_REMOVE(child, next);
if (child == bs->backing) {
assert(child != bs->file);
bs->backing = NULL;
} else if (child == bs->file) {
bs->file = NULL;
}
}
static int bdrv_child_cb_update_filename(BdrvChild *c, BlockDriverState *base,
const char *filename, Error **errp)
{
if (c->role & BDRV_CHILD_COW) {
return bdrv_backing_update_filename(c, base, filename, errp);
}
return 0;
}
AioContext *child_of_bds_get_parent_aio_context(BdrvChild *c)
{
BlockDriverState *bs = c->opaque;
IO_CODE();
return bdrv_get_aio_context(bs);
}
const BdrvChildClass child_of_bds = {
.parent_is_bds = true,
.get_parent_desc = bdrv_child_get_parent_desc,
.inherit_options = bdrv_inherited_options,
.drained_begin = bdrv_child_cb_drained_begin,
.drained_poll = bdrv_child_cb_drained_poll,
.drained_end = bdrv_child_cb_drained_end,
.attach = bdrv_child_cb_attach,
.detach = bdrv_child_cb_detach,
.inactivate = bdrv_child_cb_inactivate,
.change_aio_ctx = bdrv_child_cb_change_aio_ctx,
.update_filename = bdrv_child_cb_update_filename,
.get_parent_aio_context = child_of_bds_get_parent_aio_context,
};
AioContext *bdrv_child_get_parent_aio_context(BdrvChild *c)
{
IO_CODE();
return c->klass->get_parent_aio_context(c);
}
static int bdrv_open_flags(BlockDriverState *bs, int flags)
{
int open_flags = flags;
GLOBAL_STATE_CODE();
/*
* Clear flags that are internal to the block layer before opening the
* image.
*/
open_flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_PROTOCOL);
return open_flags;
}
static void update_flags_from_options(int *flags, QemuOpts *opts)
{
GLOBAL_STATE_CODE();
*flags &= ~(BDRV_O_CACHE_MASK | BDRV_O_RDWR | BDRV_O_AUTO_RDONLY);
if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_NO_FLUSH, false)) {
*flags |= BDRV_O_NO_FLUSH;
}
if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_DIRECT, false)) {
*flags |= BDRV_O_NOCACHE;
}
if (!qemu_opt_get_bool_del(opts, BDRV_OPT_READ_ONLY, false)) {
*flags |= BDRV_O_RDWR;
}
if (qemu_opt_get_bool_del(opts, BDRV_OPT_AUTO_READ_ONLY, false)) {
*flags |= BDRV_O_AUTO_RDONLY;
}
}
static void update_options_from_flags(QDict *options, int flags)
{
GLOBAL_STATE_CODE();
if (!qdict_haskey(options, BDRV_OPT_CACHE_DIRECT)) {
qdict_put_bool(options, BDRV_OPT_CACHE_DIRECT, flags & BDRV_O_NOCACHE);
}
if (!qdict_haskey(options, BDRV_OPT_CACHE_NO_FLUSH)) {
qdict_put_bool(options, BDRV_OPT_CACHE_NO_FLUSH,
flags & BDRV_O_NO_FLUSH);
}
if (!qdict_haskey(options, BDRV_OPT_READ_ONLY)) {
qdict_put_bool(options, BDRV_OPT_READ_ONLY, !(flags & BDRV_O_RDWR));
}
if (!qdict_haskey(options, BDRV_OPT_AUTO_READ_ONLY)) {
qdict_put_bool(options, BDRV_OPT_AUTO_READ_ONLY,
flags & BDRV_O_AUTO_RDONLY);
}
}
static void bdrv_assign_node_name(BlockDriverState *bs,
const char *node_name,
Error **errp)
{
char *gen_node_name = NULL;
GLOBAL_STATE_CODE();
if (!node_name) {
node_name = gen_node_name = id_generate(ID_BLOCK);
} else if (!id_wellformed(node_name)) {
/*
* Check for empty string or invalid characters, but not if it is
* generated (generated names use characters not available to the user)
*/
error_setg(errp, "Invalid node-name: '%s'", node_name);
return;
}
/* takes care of avoiding namespaces collisions */
if (blk_by_name(node_name)) {
error_setg(errp, "node-name=%s is conflicting with a device id",
node_name);
goto out;
}
/* takes care of avoiding duplicates node names */
if (bdrv_find_node(node_name)) {
error_setg(errp, "Duplicate nodes with node-name='%s'", node_name);
goto out;
}
/* Make sure that the node name isn't truncated */
if (strlen(node_name) >= sizeof(bs->node_name)) {
error_setg(errp, "Node name too long");
goto out;
}
/* copy node name into the bs and insert it into the graph list */
pstrcpy(bs->node_name, sizeof(bs->node_name), node_name);
QTAILQ_INSERT_TAIL(&graph_bdrv_states, bs, node_list);
out:
g_free(gen_node_name);
}
/*
* The caller must always hold @bs AioContext lock, because this function calls
* bdrv_refresh_total_sectors() which polls when called from non-coroutine
* context.
*/
static int no_coroutine_fn GRAPH_UNLOCKED
bdrv_open_driver(BlockDriverState *bs, BlockDriver *drv, const char *node_name,
QDict *options, int open_flags, Error **errp)
{
AioContext *ctx;
Error *local_err = NULL;
int i, ret;
GLOBAL_STATE_CODE();
bdrv_assign_node_name(bs, node_name, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return -EINVAL;
}
bs->drv = drv;
bs->opaque = g_malloc0(drv->instance_size);
if (drv->bdrv_file_open) {
assert(!drv->bdrv_needs_filename || bs->filename[0]);
ret = drv->bdrv_file_open(bs, options, open_flags, &local_err);
} else if (drv->bdrv_open) {
ret = drv->bdrv_open(bs, options, open_flags, &local_err);
} else {
ret = 0;
}
if (ret < 0) {
if (local_err) {
error_propagate(errp, local_err);
} else if (bs->filename[0]) {
error_setg_errno(errp, -ret, "Could not open '%s'", bs->filename);
} else {
error_setg_errno(errp, -ret, "Could not open image");
}
goto open_failed;
}
assert(!(bs->supported_read_flags & ~BDRV_REQ_MASK));
assert(!(bs->supported_write_flags & ~BDRV_REQ_MASK));
/*
* Always allow the BDRV_REQ_REGISTERED_BUF optimization hint. This saves
* drivers that pass read/write requests through to a child the trouble of
* declaring support explicitly.
*
* Drivers must not propagate this flag accidentally when they initiate I/O
* to a bounce buffer. That case should be rare though.
*/
bs->supported_read_flags |= BDRV_REQ_REGISTERED_BUF;
bs->supported_write_flags |= BDRV_REQ_REGISTERED_BUF;
/* Get the context after .bdrv_open, it can change the context */
ctx = bdrv_get_aio_context(bs);
aio_context_acquire(ctx);
ret = bdrv_refresh_total_sectors(bs, bs->total_sectors);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not refresh total sector count");
aio_context_release(ctx);
return ret;
}
bdrv_graph_rdlock_main_loop();
bdrv_refresh_limits(bs, NULL, &local_err);
bdrv_graph_rdunlock_main_loop();
aio_context_release(ctx);
if (local_err) {
error_propagate(errp, local_err);
return -EINVAL;
}
assert(bdrv_opt_mem_align(bs) != 0);
assert(bdrv_min_mem_align(bs) != 0);
assert(is_power_of_2(bs->bl.request_alignment));
for (i = 0; i < bs->quiesce_counter; i++) {
if (drv->bdrv_drain_begin) {
drv->bdrv_drain_begin(bs);
}
}
return 0;
open_failed:
bs->drv = NULL;
bdrv_graph_wrlock(NULL);
if (bs->file != NULL) {
bdrv_unref_child(bs, bs->file);
assert(!bs->file);
}
bdrv_graph_wrunlock();
g_free(bs->opaque);
bs->opaque = NULL;
return ret;
}
/*
* Create and open a block node.
*
* @options is a QDict of options to pass to the block drivers, or NULL for an
* empty set of options. The reference to the QDict belongs to the block layer
* after the call (even on failure), so if the caller intends to reuse the
* dictionary, it needs to use qobject_ref() before calling bdrv_open.
*/
BlockDriverState *bdrv_new_open_driver_opts(BlockDriver *drv,
const char *node_name,
QDict *options, int flags,
Error **errp)
{
BlockDriverState *bs;
int ret;
GLOBAL_STATE_CODE();
bs = bdrv_new();
bs->open_flags = flags;
bs->options = options ?: qdict_new();
bs->explicit_options = qdict_clone_shallow(bs->options);
bs->opaque = NULL;
update_options_from_flags(bs->options, flags);
ret = bdrv_open_driver(bs, drv, node_name, bs->options, flags, errp);
if (ret < 0) {
qobject_unref(bs->explicit_options);
bs->explicit_options = NULL;
qobject_unref(bs->options);
bs->options = NULL;
bdrv_unref(bs);
return NULL;
}
return bs;
}
/* Create and open a block node. */
BlockDriverState *bdrv_new_open_driver(BlockDriver *drv, const char *node_name,
int flags, Error **errp)
{
GLOBAL_STATE_CODE();
return bdrv_new_open_driver_opts(drv, node_name, NULL, flags, errp);
}
QemuOptsList bdrv_runtime_opts = {
.name = "bdrv_common",
.head = QTAILQ_HEAD_INITIALIZER(bdrv_runtime_opts.head),
.desc = {
{
.name = "node-name",
.type = QEMU_OPT_STRING,
.help = "Node name of the block device node",
},
{
.name = "driver",
.type = QEMU_OPT_STRING,
.help = "Block driver to use for the node",
},
{
.name = BDRV_OPT_CACHE_DIRECT,
.type = QEMU_OPT_BOOL,
.help = "Bypass software writeback cache on the host",
},
{
.name = BDRV_OPT_CACHE_NO_FLUSH,
.type = QEMU_OPT_BOOL,
.help = "Ignore flush requests",
},
{
.name = BDRV_OPT_READ_ONLY,
.type = QEMU_OPT_BOOL,
.help = "Node is opened in read-only mode",
},
{
.name = BDRV_OPT_AUTO_READ_ONLY,
.type = QEMU_OPT_BOOL,
.help = "Node can become read-only if opening read-write fails",
},
{
.name = "detect-zeroes",
.type = QEMU_OPT_STRING,
.help = "try to optimize zero writes (off, on, unmap)",
},
{
.name = BDRV_OPT_DISCARD,
.type = QEMU_OPT_STRING,
.help = "discard operation (ignore/off, unmap/on)",
},
{
.name = BDRV_OPT_FORCE_SHARE,
.type = QEMU_OPT_BOOL,
.help = "always accept other writers (default: off)",
},
{ /* end of list */ }
},
};
QemuOptsList bdrv_create_opts_simple = {
.name = "simple-create-opts",
.head = QTAILQ_HEAD_INITIALIZER(bdrv_create_opts_simple.head),
.desc = {
{
.name = BLOCK_OPT_SIZE,
.type = QEMU_OPT_SIZE,
.help = "Virtual disk size"
},
{
.name = BLOCK_OPT_PREALLOC,
.type = QEMU_OPT_STRING,
.help = "Preallocation mode (allowed values: off)"
},
{ /* end of list */ }
}
};
/*
* Common part for opening disk images and files
*
* Removes all processed options from *options.
*/
static int bdrv_open_common(BlockDriverState *bs, BlockBackend *file,
QDict *options, Error **errp)
{
int ret, open_flags;
const char *filename;
const char *driver_name = NULL;
const char *node_name = NULL;
const char *discard;
QemuOpts *opts;
BlockDriver *drv;
Error *local_err = NULL;
bool ro;
GLOBAL_STATE_CODE();
bdrv_graph_rdlock_main_loop();
assert(bs->file == NULL);
assert(options != NULL && bs->options != options);
bdrv_graph_rdunlock_main_loop();
opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort);
if (!qemu_opts_absorb_qdict(opts, options, errp)) {
ret = -EINVAL;
goto fail_opts;
}
update_flags_from_options(&bs->open_flags, opts);
driver_name = qemu_opt_get(opts, "driver");
drv = bdrv_find_format(driver_name);
assert(drv != NULL);
bs->force_share = qemu_opt_get_bool(opts, BDRV_OPT_FORCE_SHARE, false);
if (bs->force_share && (bs->open_flags & BDRV_O_RDWR)) {
error_setg(errp,
BDRV_OPT_FORCE_SHARE
"=on can only be used with read-only images");
ret = -EINVAL;
goto fail_opts;
}
if (file != NULL) {
bdrv_graph_rdlock_main_loop();
bdrv_refresh_filename(blk_bs(file));
bdrv_graph_rdunlock_main_loop();
filename = blk_bs(file)->filename;
} else {
/*
* Caution: while qdict_get_try_str() is fine, getting
* non-string types would require more care. When @options
* come from -blockdev or blockdev_add, its members are typed
* according to the QAPI schema, but when they come from
* -drive, they're all QString.
*/
filename = qdict_get_try_str(options, "filename");
}
if (drv->bdrv_needs_filename && (!filename || !filename[0])) {
error_setg(errp, "The '%s' block driver requires a file name",
drv->format_name);
ret = -EINVAL;
goto fail_opts;
}
trace_bdrv_open_common(bs, filename ?: "", bs->open_flags,
drv->format_name);
ro = bdrv_is_read_only(bs);
if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, ro)) {
if (!ro && bdrv_is_whitelisted(drv, true)) {
bdrv_graph_rdlock_main_loop();
ret = bdrv_apply_auto_read_only(bs, NULL, NULL);
bdrv_graph_rdunlock_main_loop();
} else {
ret = -ENOTSUP;
}
if (ret < 0) {
error_setg(errp,
!ro && bdrv_is_whitelisted(drv, true)
? "Driver '%s' can only be used for read-only devices"
: "Driver '%s' is not whitelisted",
drv->format_name);
goto fail_opts;
}
}
/* bdrv_new() and bdrv_close() make it so */
assert(qatomic_read(&bs->copy_on_read) == 0);
if (bs->open_flags & BDRV_O_COPY_ON_READ) {
if (!ro) {
bdrv_enable_copy_on_read(bs);
} else {
error_setg(errp, "Can't use copy-on-read on read-only device");
ret = -EINVAL;
goto fail_opts;
}
}
discard = qemu_opt_get(opts, BDRV_OPT_DISCARD);
if (discard != NULL) {
if (bdrv_parse_discard_flags(discard, &bs->open_flags) != 0) {
error_setg(errp, "Invalid discard option");
ret = -EINVAL;
goto fail_opts;
}
}
bs->detect_zeroes =
bdrv_parse_detect_zeroes(opts, bs->open_flags, &local_err);
if (local_err) {
error_propagate(errp, local_err);
ret = -EINVAL;
goto fail_opts;
}
if (filename != NULL) {
pstrcpy(bs->filename, sizeof(bs->filename), filename);
} else {
bs->filename[0] = '\0';
}
pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), bs->filename);
/* Open the image, either directly or using a protocol */
open_flags = bdrv_open_flags(bs, bs->open_flags);
node_name = qemu_opt_get(opts, "node-name");
assert(!drv->bdrv_file_open || file == NULL);
ret = bdrv_open_driver(bs, drv, node_name, options, open_flags, errp);
if (ret < 0) {
goto fail_opts;
}
qemu_opts_del(opts);
return 0;
fail_opts:
qemu_opts_del(opts);
return ret;
}
static QDict *parse_json_filename(const char *filename, Error **errp)
{
QObject *options_obj;
QDict *options;
int ret;
GLOBAL_STATE_CODE();
ret = strstart(filename, "json:", &filename);
assert(ret);
options_obj = qobject_from_json(filename, errp);
if (!options_obj) {
error_prepend(errp, "Could not parse the JSON options: ");
return NULL;
}
options = qobject_to(QDict, options_obj);
if (!options) {
qobject_unref(options_obj);
error_setg(errp, "Invalid JSON object given");
return NULL;
}
qdict_flatten(options);
return options;
}
static void parse_json_protocol(QDict *options, const char **pfilename,
Error **errp)
{
QDict *json_options;
Error *local_err = NULL;
GLOBAL_STATE_CODE();
/* Parse json: pseudo-protocol */
if (!*pfilename || !g_str_has_prefix(*pfilename, "json:")) {
return;
}
json_options = parse_json_filename(*pfilename, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return;
}
/* Options given in the filename have lower priority than options
* specified directly */
qdict_join(options, json_options, false);
qobject_unref(json_options);
*pfilename = NULL;
}
/*
* Fills in default options for opening images and converts the legacy
* filename/flags pair to option QDict entries.
* The BDRV_O_PROTOCOL flag in *flags will be set or cleared accordingly if a
* block driver has been specified explicitly.
*/
static int bdrv_fill_options(QDict **options, const char *filename,
int *flags, Error **errp)
{
const char *drvname;
bool protocol = *flags & BDRV_O_PROTOCOL;
bool parse_filename = false;
BlockDriver *drv = NULL;
Error *local_err = NULL;
GLOBAL_STATE_CODE();
/*
* Caution: while qdict_get_try_str() is fine, getting non-string
* types would require more care. When @options come from
* -blockdev or blockdev_add, its members are typed according to
* the QAPI schema, but when they come from -drive, they're all
* QString.
*/
drvname = qdict_get_try_str(*options, "driver");
if (drvname) {
drv = bdrv_find_format(drvname);
if (!drv) {
error_setg(errp, "Unknown driver '%s'", drvname);
return -ENOENT;
}
/* If the user has explicitly specified the driver, this choice should
* override the BDRV_O_PROTOCOL flag */
protocol = drv->bdrv_file_open;
}
if (protocol) {
*flags |= BDRV_O_PROTOCOL;
} else {
*flags &= ~BDRV_O_PROTOCOL;
}
/* Translate cache options from flags into options */
update_options_from_flags(*options, *flags);
/* Fetch the file name from the options QDict if necessary */
if (protocol && filename) {
if (!qdict_haskey(*options, "filename")) {
qdict_put_str(*options, "filename", filename);
parse_filename = true;
} else {
error_setg(errp, "Can't specify 'file' and 'filename' options at "
"the same time");
return -EINVAL;
}
}
/* Find the right block driver */
/* See cautionary note on accessing @options above */
filename = qdict_get_try_str(*options, "filename");
if (!drvname && protocol) {
if (filename) {
drv = bdrv_find_protocol(filename, parse_filename, errp);
if (!drv) {
return -EINVAL;
}
drvname = drv->format_name;
qdict_put_str(*options, "driver", drvname);
} else {
error_setg(errp, "Must specify either driver or file");
return -EINVAL;
}
}
assert(drv || !protocol);
/* Driver-specific filename parsing */
if (drv && drv->bdrv_parse_filename && parse_filename) {
drv->bdrv_parse_filename(filename, *options, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return -EINVAL;
}
if (!drv->bdrv_needs_filename) {
qdict_del(*options, "filename");
}
}
return 0;
}
typedef struct BlockReopenQueueEntry {
bool prepared;
BDRVReopenState state;
QTAILQ_ENTRY(BlockReopenQueueEntry) entry;
} BlockReopenQueueEntry;
/*
* Return the flags that @bs will have after the reopens in @q have
* successfully completed. If @q is NULL (or @bs is not contained in @q),
* return the current flags.
*/
static int bdrv_reopen_get_flags(BlockReopenQueue *q, BlockDriverState *bs)
{
BlockReopenQueueEntry *entry;
if (q != NULL) {
QTAILQ_FOREACH(entry, q, entry) {
if (entry->state.bs == bs) {
return entry->state.flags;
}
}
}
return bs->open_flags;
}
/* Returns whether the image file can be written to after the reopen queue @q
* has been successfully applied, or right now if @q is NULL. */
static bool bdrv_is_writable_after_reopen(BlockDriverState *bs,
BlockReopenQueue *q)
{
int flags = bdrv_reopen_get_flags(q, bs);
return (flags & (BDRV_O_RDWR | BDRV_O_INACTIVE)) == BDRV_O_RDWR;
}
/*
* Return whether the BDS can be written to. This is not necessarily
* the same as !bdrv_is_read_only(bs), as inactivated images may not
* be written to but do not count as read-only images.
*/
bool bdrv_is_writable(BlockDriverState *bs)
{
IO_CODE();
return bdrv_is_writable_after_reopen(bs, NULL);
}
static char *bdrv_child_user_desc(BdrvChild *c)
{
GLOBAL_STATE_CODE();
return c->klass->get_parent_desc(c);
}
/*
* Check that @a allows everything that @b needs. @a and @b must reference same
* child node.
*/
static bool bdrv_a_allow_b(BdrvChild *a, BdrvChild *b, Error **errp)
{
const char *child_bs_name;
g_autofree char *a_user = NULL;
g_autofree char *b_user = NULL;
g_autofree char *perms = NULL;
assert(a->bs);
assert(a->bs == b->bs);
GLOBAL_STATE_CODE();
if ((b->perm & a->shared_perm) == b->perm) {
return true;
}
child_bs_name = bdrv_get_node_name(b->bs);
a_user = bdrv_child_user_desc(a);
b_user = bdrv_child_user_desc(b);
perms = bdrv_perm_names(b->perm & ~a->shared_perm);
error_setg(errp, "Permission conflict on node '%s': permissions '%s' are "
"both required by %s (uses node '%s' as '%s' child) and "
"unshared by %s (uses node '%s' as '%s' child).",
child_bs_name, perms,
b_user, child_bs_name, b->name,
a_user, child_bs_name, a->name);
return false;
}
static bool GRAPH_RDLOCK
bdrv_parent_perms_conflict(BlockDriverState *bs, Error **errp)
{
BdrvChild *a, *b;
GLOBAL_STATE_CODE();
/*
* During the loop we'll look at each pair twice. That's correct because
* bdrv_a_allow_b() is asymmetric and we should check each pair in both
* directions.
*/
QLIST_FOREACH(a, &bs->parents, next_parent) {
QLIST_FOREACH(b, &bs->parents, next_parent) {
if (a == b) {
continue;
}
if (!bdrv_a_allow_b(a, b, errp)) {
return true;
}
}
}
return false;
}
static void GRAPH_RDLOCK
bdrv_child_perm(BlockDriverState *bs, BlockDriverState *child_bs,
BdrvChild *c, BdrvChildRole role,
BlockReopenQueue *reopen_queue,
uint64_t parent_perm, uint64_t parent_shared,
uint64_t *nperm, uint64_t *nshared)
{
assert(bs->drv && bs->drv->bdrv_child_perm);
GLOBAL_STATE_CODE();
bs->drv->bdrv_child_perm(bs, c, role, reopen_queue,
parent_perm, parent_shared,
nperm, nshared);
/* TODO Take force_share from reopen_queue */
if (child_bs && child_bs->force_share) {
*nshared = BLK_PERM_ALL;
}
}
/*
* Adds the whole subtree of @bs (including @bs itself) to the @list (except for
* nodes that are already in the @list, of course) so that final list is
* topologically sorted. Return the result (GSList @list object is updated, so
* don't use old reference after function call).
*
* On function start @list must be already topologically sorted and for any node
* in the @list the whole subtree of the node must be in the @list as well. The
* simplest way to satisfy this criteria: use only result of
* bdrv_topological_dfs() or NULL as @list parameter.
*/
static GSList * GRAPH_RDLOCK
bdrv_topological_dfs(GSList *list, GHashTable *found, BlockDriverState *bs)
{
BdrvChild *child;
g_autoptr(GHashTable) local_found = NULL;
GLOBAL_STATE_CODE();
if (!found) {
assert(!list);
found = local_found = g_hash_table_new(NULL, NULL);
}
if (g_hash_table_contains(found, bs)) {
return list;
}
g_hash_table_add(found, bs);
QLIST_FOREACH(child, &bs->children, next) {
list = bdrv_topological_dfs(list, found, child->bs);
}
return g_slist_prepend(list, bs);
}
typedef struct BdrvChildSetPermState {
BdrvChild *child;
uint64_t old_perm;
uint64_t old_shared_perm;
} BdrvChildSetPermState;
static void bdrv_child_set_perm_abort(void *opaque)
{
BdrvChildSetPermState *s = opaque;
GLOBAL_STATE_CODE();
s->child->perm = s->old_perm;
s->child->shared_perm = s->old_shared_perm;
}
static TransactionActionDrv bdrv_child_set_pem_drv = {
.abort = bdrv_child_set_perm_abort,
.clean = g_free,
};
static void bdrv_child_set_perm(BdrvChild *c, uint64_t perm,
uint64_t shared, Transaction *tran)
{
BdrvChildSetPermState *s = g_new(BdrvChildSetPermState, 1);
GLOBAL_STATE_CODE();
*s = (BdrvChildSetPermState) {
.child = c,
.old_perm = c->perm,
.old_shared_perm = c->shared_perm,
};
c->perm = perm;
c->shared_perm = shared;
tran_add(tran, &bdrv_child_set_pem_drv, s);
}
static void GRAPH_RDLOCK bdrv_drv_set_perm_commit(void *opaque)
{
BlockDriverState *bs = opaque;
uint64_t cumulative_perms, cumulative_shared_perms;
GLOBAL_STATE_CODE();
if (bs->drv->bdrv_set_perm) {
bdrv_get_cumulative_perm(bs, &cumulative_perms,
&cumulative_shared_perms);
bs->drv->bdrv_set_perm(bs, cumulative_perms, cumulative_shared_perms);
}
}
static void GRAPH_RDLOCK bdrv_drv_set_perm_abort(void *opaque)
{
BlockDriverState *bs = opaque;
GLOBAL_STATE_CODE();
if (bs->drv->bdrv_abort_perm_update) {
bs->drv->bdrv_abort_perm_update(bs);
}
}
TransactionActionDrv bdrv_drv_set_perm_drv = {
.abort = bdrv_drv_set_perm_abort,
.commit = bdrv_drv_set_perm_commit,
};
/*
* After calling this function, the transaction @tran may only be completed
* while holding a reader lock for the graph.
*/
static int GRAPH_RDLOCK
bdrv_drv_set_perm(BlockDriverState *bs, uint64_t perm, uint64_t shared_perm,
Transaction *tran, Error **errp)
{
GLOBAL_STATE_CODE();
if (!bs->drv) {
return 0;
}
if (bs->drv->bdrv_check_perm) {
int ret = bs->drv->bdrv_check_perm(bs, perm, shared_perm, errp);
if (ret < 0) {
return ret;
}
}
if (tran) {
tran_add(tran, &bdrv_drv_set_perm_drv, bs);
}
return 0;
}
typedef struct BdrvReplaceChildState {
BdrvChild *child;
BlockDriverState *old_bs;
} BdrvReplaceChildState;
static void GRAPH_WRLOCK bdrv_replace_child_commit(void *opaque)
{
BdrvReplaceChildState *s = opaque;
GLOBAL_STATE_CODE();
bdrv_schedule_unref(s->old_bs);
}
static void GRAPH_WRLOCK bdrv_replace_child_abort(void *opaque)
{
BdrvReplaceChildState *s = opaque;
BlockDriverState *new_bs = s->child->bs;
GLOBAL_STATE_CODE();
assert_bdrv_graph_writable();
/* old_bs reference is transparently moved from @s to @s->child */
if (!s->child->bs) {
/*
* The parents were undrained when removing old_bs from the child. New
* requests can't have been made, though, because the child was empty.
*
* TODO Make bdrv_replace_child_noperm() transactionable to avoid
* undraining the parent in the first place. Once this is done, having
* new_bs drained when calling bdrv_replace_child_tran() is not a
* requirement any more.
*/
bdrv_parent_drained_begin_single(s->child);
assert(!bdrv_parent_drained_poll_single(s->child));
}
assert(s->child->quiesced_parent);
bdrv_replace_child_noperm(s->child, s->old_bs);
bdrv_unref(new_bs);
}
static TransactionActionDrv bdrv_replace_child_drv = {
.commit = bdrv_replace_child_commit,
.abort = bdrv_replace_child_abort,
.clean = g_free,
};
/*
* bdrv_replace_child_tran
*
* Note: real unref of old_bs is done only on commit.
*
* Both @child->bs and @new_bs (if non-NULL) must be drained. @new_bs must be
* kept drained until the transaction is completed.
*
* After calling this function, the transaction @tran may only be completed
* while holding a writer lock for the graph.
*
* The function doesn't update permissions, caller is responsible for this.
*/
static void GRAPH_WRLOCK
bdrv_replace_child_tran(BdrvChild *child, BlockDriverState *new_bs,
Transaction *tran)
{
BdrvReplaceChildState *s = g_new(BdrvReplaceChildState, 1);
assert(child->quiesced_parent);
assert(!new_bs || new_bs->quiesce_counter);
*s = (BdrvReplaceChildState) {
.child = child,
.old_bs = child->bs,
};
tran_add(tran, &bdrv_replace_child_drv, s);
if (new_bs) {
bdrv_ref(new_bs);
}
bdrv_replace_child_noperm(child, new_bs);
/* old_bs reference is transparently moved from @child to @s */
}
/*
* Refresh permissions in @bs subtree. The function is intended to be called
* after some graph modification that was done without permission update.
*
* After calling this function, the transaction @tran may only be completed
* while holding a reader lock for the graph.
*/
static int GRAPH_RDLOCK
bdrv_node_refresh_perm(BlockDriverState *bs, BlockReopenQueue *q,
Transaction *tran, Error **errp)
{
BlockDriver *drv = bs->drv;
BdrvChild *c;
int ret;
uint64_t cumulative_perms, cumulative_shared_perms;
GLOBAL_STATE_CODE();
bdrv_get_cumulative_perm(bs, &cumulative_perms, &cumulative_shared_perms);
/* Write permissions never work with read-only images */
if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) &&
!bdrv_is_writable_after_reopen(bs, q))
{
if (!bdrv_is_writable_after_reopen(bs, NULL)) {
error_setg(errp, "Block node is read-only");
} else {
error_setg(errp, "Read-only block node '%s' cannot support "
"read-write users", bdrv_get_node_name(bs));
}
return -EPERM;
}
/*
* Unaligned requests will automatically be aligned to bl.request_alignment
* and without RESIZE we can't extend requests to write to space beyond the
* end of the image, so it's required that the image size is aligned.
*/
if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) &&
!(cumulative_perms & BLK_PERM_RESIZE))
{
if ((bs->total_sectors * BDRV_SECTOR_SIZE) % bs->bl.request_alignment) {
error_setg(errp, "Cannot get 'write' permission without 'resize': "
"Image size is not a multiple of request "
"alignment");
return -EPERM;
}
}
/* Check this node */
if (!drv) {
return 0;
}
ret = bdrv_drv_set_perm(bs, cumulative_perms, cumulative_shared_perms, tran,
errp);
if (ret < 0) {
return ret;
}
/* Drivers that never have children can omit .bdrv_child_perm() */
if (!drv->bdrv_child_perm) {
assert(QLIST_EMPTY(&bs->children));
return 0;
}
/* Check all children */
QLIST_FOREACH(c, &bs->children, next) {
uint64_t cur_perm, cur_shared;
bdrv_child_perm(bs, c->bs, c, c->role, q,
cumulative_perms, cumulative_shared_perms,
&cur_perm, &cur_shared);
bdrv_child_set_perm(c, cur_perm, cur_shared, tran);
}
return 0;
}
/*
* @list is a product of bdrv_topological_dfs() (may be called several times) -
* a topologically sorted subgraph.
*
* After calling this function, the transaction @tran may only be completed
* while holding a reader lock for the graph.
*/
static int GRAPH_RDLOCK
bdrv_do_refresh_perms(GSList *list, BlockReopenQueue *q, Transaction *tran,
Error **errp)
{
int ret;
BlockDriverState *bs;
GLOBAL_STATE_CODE();
for ( ; list; list = list->next) {
bs = list->data;
if (bdrv_parent_perms_conflict(bs, errp)) {
return -EINVAL;
}
ret = bdrv_node_refresh_perm(bs, q, tran, errp);
if (ret < 0) {
return ret;
}
}
return 0;
}
/*
* @list is any list of nodes. List is completed by all subtrees and
* topologically sorted. It's not a problem if some node occurs in the @list
* several times.
*
* After calling this function, the transaction @tran may only be completed
* while holding a reader lock for the graph.
*/
static int GRAPH_RDLOCK
bdrv_list_refresh_perms(GSList *list, BlockReopenQueue *q, Transaction *tran,
Error **errp)
{
g_autoptr(GHashTable) found = g_hash_table_new(NULL, NULL);
g_autoptr(GSList) refresh_list = NULL;
for ( ; list; list = list->next) {
refresh_list = bdrv_topological_dfs(refresh_list, found, list->data);
}
return bdrv_do_refresh_perms(refresh_list, q, tran, errp);
}
void bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm,
uint64_t *shared_perm)
{
BdrvChild *c;
uint64_t cumulative_perms = 0;
uint64_t cumulative_shared_perms = BLK_PERM_ALL;
GLOBAL_STATE_CODE();
QLIST_FOREACH(c, &bs->parents, next_parent) {
cumulative_perms |= c->perm;
cumulative_shared_perms &= c->shared_perm;
}
*perm = cumulative_perms;
*shared_perm = cumulative_shared_perms;
}
char *bdrv_perm_names(uint64_t perm)
{
struct perm_name {
uint64_t perm;
const char *name;
} permissions[] = {
{ BLK_PERM_CONSISTENT_READ, "consistent read" },
{ BLK_PERM_WRITE, "write" },
{ BLK_PERM_WRITE_UNCHANGED, "write unchanged" },
{ BLK_PERM_RESIZE, "resize" },
{ 0, NULL }
};
GString *result = g_string_sized_new(30);
struct perm_name *p;
for (p = permissions; p->name; p++) {
if (perm & p->perm) {
if (result->len > 0) {
g_string_append(result, ", ");
}
g_string_append(result, p->name);
}
}
return g_string_free(result, FALSE);
}
/*
* @tran is allowed to be NULL. In this case no rollback is possible.
*
* After calling this function, the transaction @tran may only be completed
* while holding a reader lock for the graph.
*/
static int GRAPH_RDLOCK
bdrv_refresh_perms(BlockDriverState *bs, Transaction *tran, Error **errp)
{
int ret;
Transaction *local_tran = NULL;
g_autoptr(GSList) list = bdrv_topological_dfs(NULL, NULL, bs);
GLOBAL_STATE_CODE();
if (!tran) {
tran = local_tran = tran_new();
}
ret = bdrv_do_refresh_perms(list, NULL, tran, errp);
if (local_tran) {
tran_finalize(local_tran, ret);
}
return ret;
}
int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared,
Error **errp)
{
Error *local_err = NULL;
Transaction *tran = tran_new();
int ret;
GLOBAL_STATE_CODE();
bdrv_child_set_perm(c, perm, shared, tran);
ret = bdrv_refresh_perms(c->bs, tran, &local_err);
tran_finalize(tran, ret);
if (ret < 0) {
if ((perm & ~c->perm) || (c->shared_perm & ~shared)) {
/* tighten permissions */
error_propagate(errp, local_err);
} else {
/*
* Our caller may intend to only loosen restrictions and
* does not expect this function to fail. Errors are not
* fatal in such a case, so we can just hide them from our
* caller.
*/
error_free(local_err);
ret = 0;
}
}
return ret;
}
int bdrv_child_refresh_perms(BlockDriverState *bs, BdrvChild *c, Error **errp)
{
uint64_t parent_perms, parent_shared;
uint64_t perms, shared;
GLOBAL_STATE_CODE();
bdrv_get_cumulative_perm(bs, &parent_perms, &parent_shared);
bdrv_child_perm(bs, c->bs, c, c->role, NULL,
parent_perms, parent_shared, &perms, &shared);
return bdrv_child_try_set_perm(c, perms, shared, errp);
}
/*
* Default implementation for .bdrv_child_perm() for block filters:
* Forward CONSISTENT_READ, WRITE, WRITE_UNCHANGED, and RESIZE to the
* filtered child.
*/
static void bdrv_filter_default_perms(BlockDriverState *bs, BdrvChild *c,
BdrvChildRole role,
BlockReopenQueue *reopen_queue,
uint64_t perm, uint64_t shared,
uint64_t *nperm, uint64_t *nshared)
{
GLOBAL_STATE_CODE();
*nperm = perm & DEFAULT_PERM_PASSTHROUGH;
*nshared = (shared & DEFAULT_PERM_PASSTHROUGH) | DEFAULT_PERM_UNCHANGED;
}
static void bdrv_default_perms_for_cow(BlockDriverState *bs, BdrvChild *c,
BdrvChildRole role,
BlockReopenQueue *reopen_queue,
uint64_t perm, uint64_t shared,
uint64_t *nperm, uint64_t *nshared)
{
assert(role & BDRV_CHILD_COW);
GLOBAL_STATE_CODE();
/*
* We want consistent read from backing files if the parent needs it.
* No other operations are performed on backing files.
*/
perm &= BLK_PERM_CONSISTENT_READ;
/*
* If the parent can deal with changing data, we're okay with a
* writable and resizable backing file.
* TODO Require !(perm & BLK_PERM_CONSISTENT_READ), too?
*/
if (shared & BLK_PERM_WRITE) {
shared = BLK_PERM_WRITE | BLK_PERM_RESIZE;
} else {
shared = 0;
}
shared |= BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED;
if (bs->open_flags & BDRV_O_INACTIVE) {
shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
}
*nperm = perm;
*nshared = shared;
}
static void bdrv_default_perms_for_storage(BlockDriverState *bs, BdrvChild *c,
BdrvChildRole role,
BlockReopenQueue *reopen_queue,
uint64_t perm, uint64_t shared,
uint64_t *nperm, uint64_t *nshared)
{
int flags;
GLOBAL_STATE_CODE();
assert(role & (BDRV_CHILD_METADATA | BDRV_CHILD_DATA));
flags = bdrv_reopen_get_flags(reopen_queue, bs);
/*
* Apart from the modifications below, the same permissions are
* forwarded and left alone as for filters
*/
bdrv_filter_default_perms(bs, c, role, reopen_queue,
perm, shared, &perm, &shared);
if (role & BDRV_CHILD_METADATA) {
/* Format drivers may touch metadata even if the guest doesn't write */
if (bdrv_is_writable_after_reopen(bs, reopen_queue)) {
perm |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
}
/*
* bs->file always needs to be consistent because of the
* metadata. We can never allow other users to resize or write
* to it.
*/
if (!(flags & BDRV_O_NO_IO)) {
perm |= BLK_PERM_CONSISTENT_READ;
}
shared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE);
}
if (role & BDRV_CHILD_DATA) {
/*
* Technically, everything in this block is a subset of the
* BDRV_CHILD_METADATA path taken above, and so this could
* be an "else if" branch. However, that is not obvious, and
* this function is not performance critical, therefore we let
* this be an independent "if".
*/
/*
* We cannot allow other users to resize the file because the
* format driver might have some assumptions about the size
* (e.g. because it is stored in metadata, or because the file
* is split into fixed-size data files).
*/
shared &= ~BLK_PERM_RESIZE;
/*
* WRITE_UNCHANGED often cannot be performed as such on the
* data file. For example, the qcow2 driver may still need to
* write copied clusters on copy-on-read.
*/
if (perm & BLK_PERM_WRITE_UNCHANGED) {
perm |= BLK_PERM_WRITE;
}
/*
* If the data file is written to, the format driver may
* expect to be able to resize it by writing beyond the EOF.
*/
if (perm & BLK_PERM_WRITE) {
perm |= BLK_PERM_RESIZE;
}
}
if (bs->open_flags & BDRV_O_INACTIVE) {
shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
}
*nperm = perm;
*nshared = shared;
}
void bdrv_default_perms(BlockDriverState *bs, BdrvChild *c,
BdrvChildRole role, BlockReopenQueue *reopen_queue,
uint64_t perm, uint64_t shared,
uint64_t *nperm, uint64_t *nshared)
{
GLOBAL_STATE_CODE();
if (role & BDRV_CHILD_FILTERED) {
assert(!(role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA |
BDRV_CHILD_COW)));
bdrv_filter_default_perms(bs, c, role, reopen_queue,
perm, shared, nperm, nshared);
} else if (role & BDRV_CHILD_COW) {
assert(!(role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA)));
bdrv_default_perms_for_cow(bs, c, role, reopen_queue,
perm, shared, nperm, nshared);
} else if (role & (BDRV_CHILD_METADATA | BDRV_CHILD_DATA)) {
bdrv_default_perms_for_storage(bs, c, role, reopen_queue,
perm, shared, nperm, nshared);
} else {
g_assert_not_reached();
}
}
uint64_t bdrv_qapi_perm_to_blk_perm(BlockPermission qapi_perm)
{
static const uint64_t permissions[] = {
[BLOCK_PERMISSION_CONSISTENT_READ] = BLK_PERM_CONSISTENT_READ,
[BLOCK_PERMISSION_WRITE] = BLK_PERM_WRITE,
[BLOCK_PERMISSION_WRITE_UNCHANGED] = BLK_PERM_WRITE_UNCHANGED,
[BLOCK_PERMISSION_RESIZE] = BLK_PERM_RESIZE,
};
QEMU_BUILD_BUG_ON(ARRAY_SIZE(permissions) != BLOCK_PERMISSION__MAX);
QEMU_BUILD_BUG_ON(1UL << ARRAY_SIZE(permissions) != BLK_PERM_ALL + 1);
assert(qapi_perm < BLOCK_PERMISSION__MAX);
return permissions[qapi_perm];
}
/*
* Replaces the node that a BdrvChild points to without updating permissions.
*
* If @new_bs is non-NULL, the parent of @child must already be drained through
* @child and the caller must hold the AioContext lock for @new_bs.
*/
static void GRAPH_WRLOCK
bdrv_replace_child_noperm(BdrvChild *child, BlockDriverState *new_bs)
{
BlockDriverState *old_bs = child->bs;
int new_bs_quiesce_counter;
assert(!child->frozen);
/*
* If we want to change the BdrvChild to point to a drained node as its new
* child->bs, we need to make sure that its new parent is drained, too. In
* other words, either child->quiesce_parent must already be true or we must
* be able to set it and keep the parent's quiesce_counter consistent with
* that, but without polling or starting new requests (this function
* guarantees that it doesn't poll, and starting new requests would be
* against the invariants of drain sections).
*
* To keep things simple, we pick the first option (child->quiesce_parent
* must already be true). We also generalise the rule a bit to make it
* easier to verify in callers and more likely to be covered in test cases:
* The parent must be quiesced through this child even if new_bs isn't
* currently drained.
*
* The only exception is for callers that always pass new_bs == NULL. In
* this case, we obviously never need to consider the case of a drained
* new_bs, so we can keep the callers simpler by allowing them not to drain
* the parent.
*/
assert(!new_bs || child->quiesced_parent);
assert(old_bs != new_bs);
GLOBAL_STATE_CODE();
if (old_bs && new_bs) {
assert(bdrv_get_aio_context(old_bs) == bdrv_get_aio_context(new_bs));
}
if (old_bs) {
if (child->klass->detach) {
child->klass->detach(child);
}
QLIST_REMOVE(child, next_parent);
}
child->bs = new_bs;
if (new_bs) {
QLIST_INSERT_HEAD(&new_bs->parents, child, next_parent);
if (child->klass->attach) {
child->klass->attach(child);
}
}
/*
* If the parent was drained through this BdrvChild previously, but new_bs
* is not drained, allow requests to come in only after the new node has
* been attached.
*/
new_bs_quiesce_counter = (new_bs ? new_bs->quiesce_counter : 0);
if (!new_bs_quiesce_counter && child->quiesced_parent) {
bdrv_parent_drained_end_single(child);
}
}
/**
* Free the given @child.
*
* The child must be empty (i.e. `child->bs == NULL`) and it must be
* unused (i.e. not in a children list).
*/
static void bdrv_child_free(BdrvChild *child)
{
assert(!child->bs);
GLOBAL_STATE_CODE();
GRAPH_RDLOCK_GUARD_MAINLOOP();
assert(!child->next.le_prev); /* not in children list */
g_free(child->name);
g_free(child);
}
typedef struct BdrvAttachChildCommonState {
BdrvChild *child;
AioContext *old_parent_ctx;
AioContext *old_child_ctx;
} BdrvAttachChildCommonState;
static void GRAPH_WRLOCK bdrv_attach_child_common_abort(void *opaque)
{
BdrvAttachChildCommonState *s = opaque;
BlockDriverState *bs = s->child->bs;
GLOBAL_STATE_CODE();
assert_bdrv_graph_writable();
bdrv_replace_child_noperm(s->child, NULL);
if (bdrv_get_aio_context(bs) != s->old_child_ctx) {
bdrv_try_change_aio_context(bs, s->old_child_ctx, NULL, &error_abort);
}
if (bdrv_child_get_parent_aio_context(s->child) != s->old_parent_ctx) {
Transaction *tran;
GHashTable *visited;
bool ret;
tran = tran_new();
/* No need to visit `child`, because it has been detached already */
visited = g_hash_table_new(NULL, NULL);
ret = s->child->klass->change_aio_ctx(s->child, s->old_parent_ctx,
visited, tran, &error_abort);
g_hash_table_destroy(visited);
/* transaction is supposed to always succeed */
assert(ret == true);
tran_commit(tran);
}
bdrv_schedule_unref(bs);
bdrv_child_free(s->child);
}
static TransactionActionDrv bdrv_attach_child_common_drv = {
.abort = bdrv_attach_child_common_abort,
.clean = g_free,
};
/*
* Common part of attaching bdrv child to bs or to blk or to job
*
* Function doesn't update permissions, caller is responsible for this.
*
* After calling this function, the transaction @tran may only be completed
* while holding a writer lock for the graph.
*
* Returns new created child.
*
* The caller must hold the AioContext lock for @child_bs. Both @parent_bs and
* @child_bs can move to a different AioContext in this function. Callers must
* make sure that their AioContext locking is still correct after this.
*/
static BdrvChild * GRAPH_WRLOCK
bdrv_attach_child_common(BlockDriverState *child_bs,
const char *child_name,
const BdrvChildClass *child_class,
BdrvChildRole child_role,
uint64_t perm, uint64_t shared_perm,
void *opaque,
Transaction *tran, Error **errp)
{
BdrvChild *new_child;
AioContext *parent_ctx, *new_child_ctx;
AioContext *child_ctx = bdrv_get_aio_context(child_bs);
assert(child_class->get_parent_desc);
GLOBAL_STATE_CODE();
new_child = g_new(BdrvChild, 1);
*new_child = (BdrvChild) {
.bs = NULL,
.name = g_strdup(child_name),
.klass = child_class,
.role = child_role,
.perm = perm,
.shared_perm = shared_perm,
.opaque = opaque,
};
/*
* If the AioContexts don't match, first try to move the subtree of
* child_bs into the AioContext of the new parent. If this doesn't work,
* try moving the parent into the AioContext of child_bs instead.
*/
parent_ctx = bdrv_child_get_parent_aio_context(new_child);
if (child_ctx != parent_ctx) {
Error *local_err = NULL;
int ret = bdrv_try_change_aio_context(child_bs, parent_ctx, NULL,
&local_err);
if (ret < 0 && child_class->change_aio_ctx) {
Transaction *aio_ctx_tran = tran_new();
GHashTable *visited = g_hash_table_new(NULL, NULL);
bool ret_child;
g_hash_table_add(visited, new_child);
ret_child = child_class->change_aio_ctx(new_child, child_ctx,
visited, aio_ctx_tran,
NULL);
if (ret_child == true) {
error_free(local_err);
ret = 0;
}
tran_finalize(aio_ctx_tran, ret_child == true ? 0 : -1);
g_hash_table_destroy(visited);
}
if (ret < 0) {
error_propagate(errp, local_err);
bdrv_child_free(new_child);
return NULL;
}
}
new_child_ctx = bdrv_get_aio_context(child_bs);
if (new_child_ctx != child_ctx) {
aio_context_release(child_ctx);
aio_context_acquire(new_child_ctx);
}
bdrv_ref(child_bs);
/*
* Let every new BdrvChild start with a drained parent. Inserting the child
* in the graph with bdrv_replace_child_noperm() will undrain it if
* @child_bs is not drained.
*
* The child was only just created and is not yet visible in global state
* until bdrv_replace_child_noperm() inserts it into the graph, so nobody
* could have sent requests and polling is not necessary.
*
* Note that this means that the parent isn't fully drained yet, we only
* stop new requests from coming in. This is fine, we don't care about the
* old requests here, they are not for this child. If another place enters a
* drain section for the same parent, but wants it to be fully quiesced, it
* will not run most of the the code in .drained_begin() again (which is not
* a problem, we already did this), but it will still poll until the parent
* is fully quiesced, so it will not be negatively affected either.
*/
bdrv_parent_drained_begin_single(new_child);
bdrv_replace_child_noperm(new_child, child_bs);
BdrvAttachChildCommonState *s = g_new(BdrvAttachChildCommonState, 1);
*s = (BdrvAttachChildCommonState) {
.child = new_child,
.old_parent_ctx = parent_ctx,
.old_child_ctx = child_ctx,
};
tran_add(tran, &bdrv_attach_child_common_drv, s);
if (new_child_ctx != child_ctx) {
aio_context_release(new_child_ctx);
aio_context_acquire(child_ctx);
}
return new_child;
}
/*
* Function doesn't update permissions, caller is responsible for this.
*
* The caller must hold the AioContext lock for @child_bs. Both @parent_bs and
* @child_bs can move to a different AioContext in this function. Callers must
* make sure that their AioContext locking is still correct after this.
*
* After calling this function, the transaction @tran may only be completed
* while holding a writer lock for the graph.
*/
static BdrvChild * GRAPH_WRLOCK
bdrv_attach_child_noperm(BlockDriverState *parent_bs,
BlockDriverState *child_bs,
const char *child_name,
const BdrvChildClass *child_class,
BdrvChildRole child_role,
Transaction *tran,
Error **errp)
{
uint64_t perm, shared_perm;
assert(parent_bs->drv);
GLOBAL_STATE_CODE();
if (bdrv_recurse_has_child(child_bs, parent_bs)) {
error_setg(errp, "Making '%s' a %s child of '%s' would create a cycle",
child_bs->node_name, child_name, parent_bs->node_name);
return NULL;
}
bdrv_get_cumulative_perm(parent_bs, &perm, &shared_perm);
bdrv_child_perm(parent_bs, child_bs, NULL, child_role, NULL,
perm, shared_perm, &perm, &shared_perm);
return bdrv_attach_child_common(child_bs, child_name, child_class,
child_role, perm, shared_perm, parent_bs,
tran, errp);
}
/*
* This function steals the reference to child_bs from the caller.
* That reference is later dropped by bdrv_root_unref_child().
*
* On failure NULL is returned, errp is set and the reference to
* child_bs is also dropped.
*
* The caller must hold the AioContext lock @child_bs, but not that of @ctx
* (unless @child_bs is already in @ctx).
*/
BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs,
const char *child_name,
const BdrvChildClass *child_class,
BdrvChildRole child_role,
uint64_t perm, uint64_t shared_perm,
void *opaque, Error **errp)
{
int ret;
BdrvChild *child;
Transaction *tran = tran_new();
GLOBAL_STATE_CODE();
child = bdrv_attach_child_common(child_bs, child_name, child_class,
child_role, perm, shared_perm, opaque,
tran, errp);
if (!child) {
ret = -EINVAL;
goto out;
}
ret = bdrv_refresh_perms(child_bs, tran, errp);
out:
tran_finalize(tran, ret);
bdrv_schedule_unref(child_bs);
return ret < 0 ? NULL : child;
}
/*
* This function transfers the reference to child_bs from the caller
* to parent_bs. That reference is later dropped by parent_bs on
* bdrv_close() or if someone calls bdrv_unref_child().
*
* On failure NULL is returned, errp is set and the reference to
* child_bs is also dropped.
*
* If @parent_bs and @child_bs are in different AioContexts, the caller must
* hold the AioContext lock for @child_bs, but not for @parent_bs.
*/
BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs,
BlockDriverState *child_bs,
const char *child_name,
const BdrvChildClass *child_class,
BdrvChildRole child_role,
Error **errp)
{
int ret;
BdrvChild *child;
Transaction *tran = tran_new();
GLOBAL_STATE_CODE();
child = bdrv_attach_child_noperm(parent_bs, child_bs, child_name,
child_class, child_role, tran, errp);
if (!child) {
ret = -EINVAL;
goto out;
}
ret = bdrv_refresh_perms(parent_bs, tran, errp);
if (ret < 0) {
goto out;
}
out:
tran_finalize(tran, ret);
bdrv_schedule_unref(child_bs);
return ret < 0 ? NULL : child;
}
/* Callers must ensure that child->frozen is false. */
void bdrv_root_unref_child(BdrvChild *child)
{
BlockDriverState *child_bs = child->bs;
GLOBAL_STATE_CODE();
bdrv_replace_child_noperm(child, NULL);
bdrv_child_free(child);
if (child_bs) {
/*
* Update permissions for old node. We're just taking a parent away, so
* we're loosening restrictions. Errors of permission update are not
* fatal in this case, ignore them.
*/
bdrv_refresh_perms(child_bs, NULL, NULL);
/*
* When the parent requiring a non-default AioContext is removed, the
* node moves back to the main AioContext
*/
bdrv_try_change_aio_context(child_bs, qemu_get_aio_context(), NULL,
NULL);
}
bdrv_schedule_unref(child_bs);
}
typedef struct BdrvSetInheritsFrom {
BlockDriverState *bs;
BlockDriverState *old_inherits_from;
} BdrvSetInheritsFrom;
static void bdrv_set_inherits_from_abort(void *opaque)
{
BdrvSetInheritsFrom *s = opaque;
s->bs->inherits_from = s->old_inherits_from;
}
static TransactionActionDrv bdrv_set_inherits_from_drv = {
.abort = bdrv_set_inherits_from_abort,
.clean = g_free,
};
/* @tran is allowed to be NULL. In this case no rollback is possible */
static void bdrv_set_inherits_from(BlockDriverState *bs,
BlockDriverState *new_inherits_from,
Transaction *tran)
{
if (tran) {
BdrvSetInheritsFrom *s = g_new(BdrvSetInheritsFrom, 1);
*s = (BdrvSetInheritsFrom) {
.bs = bs,
.old_inherits_from = bs->inherits_from,
};
tran_add(tran, &bdrv_set_inherits_from_drv, s);
}
bs->inherits_from = new_inherits_from;
}
/**
* Clear all inherits_from pointers from children and grandchildren of
* @root that point to @root, where necessary.
* @tran is allowed to be NULL. In this case no rollback is possible
*/
static void GRAPH_WRLOCK
bdrv_unset_inherits_from(BlockDriverState *root, BdrvChild *child,
Transaction *tran)
{
BdrvChild *c;
if (child->bs->inherits_from == root) {
/*
* Remove inherits_from only when the last reference between root and
* child->bs goes away.
*/
QLIST_FOREACH(c, &root->children, next) {
if (c != child && c->bs == child->bs) {
break;
}
}
if (c == NULL) {
bdrv_set_inherits_from(child->bs, NULL, tran);
}
}
QLIST_FOREACH(c, &child->bs->children, next) {
bdrv_unset_inherits_from(root, c, tran);
}
}
/* Callers must ensure that child->frozen is false. */
void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child)
{
GLOBAL_STATE_CODE();
if (child == NULL) {
return;
}
bdrv_unset_inherits_from(parent, child, NULL);
bdrv_root_unref_child(child);
}
static void GRAPH_RDLOCK
bdrv_parent_cb_change_media(BlockDriverState *bs, bool load)
{
BdrvChild *c;
GLOBAL_STATE_CODE();
QLIST_FOREACH(c, &bs->parents, next_parent) {
if (c->klass->change_media) {
c->klass->change_media(c, load);
}
}
}
/* Return true if you can reach parent going through child->inherits_from
* recursively. If parent or child are NULL, return false */
static bool bdrv_inherits_from_recursive(BlockDriverState *child,
BlockDriverState *parent)
{
while (child && child != parent) {
child = child->inherits_from;
}
return child != NULL;
}
/*
* Return the BdrvChildRole for @bs's backing child. bs->backing is
* mostly used for COW backing children (role = COW), but also for
* filtered children (role = FILTERED | PRIMARY).
*/
static BdrvChildRole bdrv_backing_role(BlockDriverState *bs)
{
if (bs->drv && bs->drv->is_filter) {
return BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY;
} else {
return BDRV_CHILD_COW;
}
}
/*
* Sets the bs->backing or bs->file link of a BDS. A new reference is created;
* callers which don't need their own reference any more must call bdrv_unref().
*
* If the respective child is already present (i.e. we're detaching a node),
* that child node must be drained.
*
* Function doesn't update permissions, caller is responsible for this.
*
* The caller must hold the AioContext lock for @child_bs. Both @parent_bs and
* @child_bs can move to a different AioContext in this function. Callers must
* make sure that their AioContext locking is still correct after this.
*
* After calling this function, the transaction @tran may only be completed
* while holding a writer lock for the graph.
*/
static int GRAPH_WRLOCK
bdrv_set_file_or_backing_noperm(BlockDriverState *parent_bs,
BlockDriverState *child_bs,
bool is_backing,
Transaction *tran, Error **errp)
{
bool update_inherits_from =
bdrv_inherits_from_recursive(child_bs, parent_bs);
BdrvChild *child = is_backing ? parent_bs->backing : parent_bs->file;
BdrvChildRole role;
GLOBAL_STATE_CODE();
if (!parent_bs->drv) {
/*
* Node without drv is an object without a class :/. TODO: finally fix
* qcow2 driver to never clear bs->drv and implement format corruption
* handling in other way.
*/
error_setg(errp, "Node corrupted");
return -EINVAL;
}
if (child && child->frozen) {
error_setg(errp, "Cannot change frozen '%s' link from '%s' to '%s'",
child->name, parent_bs->node_name, child->bs->node_name);
return -EPERM;
}
if (is_backing && !parent_bs->drv->is_filter &&
!parent_bs->drv->supports_backing)
{
error_setg(errp, "Driver '%s' of node '%s' does not support backing "
"files", parent_bs->drv->format_name, parent_bs->node_name);
return -EINVAL;
}
if (parent_bs->drv->is_filter) {
role = BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY;
} else if (is_backing) {
role = BDRV_CHILD_COW;
} else {
/*
* We only can use same role as it is in existing child. We don't have
* infrastructure to determine role of file child in generic way
*/
if (!child) {
error_setg(errp, "Cannot set file child to format node without "
"file child");
return -EINVAL;
}
role = child->role;
}
if (child) {
assert(child->bs->quiesce_counter);
bdrv_unset_inherits_from(parent_bs, child, tran);
bdrv_remove_child(child, tran);
}
if (!child_bs) {
goto out;
}
child = bdrv_attach_child_noperm(parent_bs, child_bs,
is_backing ? "backing" : "file",
&child_of_bds, role,
tran, errp);
if (!child) {
return -EINVAL;
}
/*
* If inherits_from pointed recursively to bs then let's update it to
* point directly to bs (else it will become NULL).
*/
if (update_inherits_from) {
bdrv_set_inherits_from(child_bs, parent_bs, tran);
}
out:
bdrv_refresh_limits(parent_bs, tran, NULL);
return 0;
}
/*
* The caller must hold the AioContext lock for @backing_hd. Both @bs and
* @backing_hd can move to a different AioContext in this function. Callers must
* make sure that their AioContext locking is still correct after this.
*
* If a backing child is already present (i.e. we're detaching a node), that
* child node must be drained.
*/
int bdrv_set_backing_hd_drained(BlockDriverState *bs,
BlockDriverState *backing_hd,
Error **errp)
{
int ret;
Transaction *tran = tran_new();
GLOBAL_STATE_CODE();
assert(bs->quiesce_counter > 0);
if (bs->backing) {
assert(bs->backing->bs->quiesce_counter > 0);
}
ret = bdrv_set_file_or_backing_noperm(bs, backing_hd, true, tran, errp);
if (ret < 0) {
goto out;
}
ret = bdrv_refresh_perms(bs, tran, errp);
out:
tran_finalize(tran, ret);
return ret;
}
int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
Error **errp)
{
BlockDriverState *drain_bs;
int ret;
GLOBAL_STATE_CODE();
bdrv_graph_rdlock_main_loop();
drain_bs = bs->backing ? bs->backing->bs : bs;
bdrv_graph_rdunlock_main_loop();
bdrv_ref(drain_bs);
bdrv_drained_begin(drain_bs);
bdrv_graph_wrlock(backing_hd);
ret = bdrv_set_backing_hd_drained(bs, backing_hd, errp);
bdrv_graph_wrunlock();
bdrv_drained_end(drain_bs);
bdrv_unref(drain_bs);
return ret;
}
/*
* Opens the backing file for a BlockDriverState if not yet open
*
* bdref_key specifies the key for the image's BlockdevRef in the options QDict.
* That QDict has to be flattened; therefore, if the BlockdevRef is a QDict
* itself, all options starting with "${bdref_key}." are considered part of the
* BlockdevRef.
*
* The caller must hold the main AioContext lock.
*
* TODO Can this be unified with bdrv_open_image()?
*/
int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
const char *bdref_key, Error **errp)
{
char *backing_filename = NULL;
char *bdref_key_dot;
const char *reference = NULL;
int ret = 0;
bool implicit_backing = false;
BlockDriverState *backing_hd;
AioContext *backing_hd_ctx;
QDict *options;
QDict *tmp_parent_options = NULL;
Error *local_err = NULL;
GLOBAL_STATE_CODE();
GRAPH_RDLOCK_GUARD_MAINLOOP();
if (bs->backing != NULL) {
goto free_exit;
}
/* NULL means an empty set of options */
if (parent_options == NULL) {
tmp_parent_options = qdict_new();
parent_options = tmp_parent_options;
}
bs->open_flags &= ~BDRV_O_NO_BACKING;
bdref_key_dot = g_strdup_printf("%s.", bdref_key);
qdict_extract_subqdict(parent_options, &options, bdref_key_dot);
g_free(bdref_key_dot);
/*
* Caution: while qdict_get_try_str() is fine, getting non-string
* types would require more care. When @parent_options come from
* -blockdev or blockdev_add, its members are typed according to
* the QAPI schema, but when they come from -drive, they're all
* QString.
*/
reference = qdict_get_try_str(parent_options, bdref_key);
if (reference || qdict_haskey(options, "file.filename")) {
/* keep backing_filename NULL */
} else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) {
qobject_unref(options);
goto free_exit;
} else {
if (qdict_size(options) == 0) {
/* If the user specifies options that do not modify the
* backing file's behavior, we might still consider it the
* implicit backing file. But it's easier this way, and
* just specifying some of the backing BDS's options is
* only possible with -drive anyway (otherwise the QAPI
* schema forces the user to specify everything). */
implicit_backing = !strcmp(bs->auto_backing_file, bs->backing_file);
}
backing_filename = bdrv_get_full_backing_filename(bs, &local_err);
if (local_err) {
ret = -EINVAL;
error_propagate(errp, local_err);
qobject_unref(options);
goto free_exit;
}
}
if (!bs->drv || !bs->drv->supports_backing) {
ret = -EINVAL;
error_setg(errp, "Driver doesn't support backing files");
qobject_unref(options);
goto free_exit;
}
if (!reference &&
bs->backing_format[0] != '\0' && !qdict_haskey(options, "driver")) {
qdict_put_str(options, "driver", bs->backing_format);
}
backing_hd = bdrv_open_inherit(backing_filename, reference, options, 0, bs,
&child_of_bds, bdrv_backing_role(bs), errp);
if (!backing_hd) {
bs->open_flags |= BDRV_O_NO_BACKING;
error_prepend(errp, "Could not open backing file: ");
ret = -EINVAL;
goto free_exit;
}
if (implicit_backing) {
bdrv_refresh_filename(backing_hd);
pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file),
backing_hd->filename);
}
/* Hook up the backing file link; drop our reference, bs owns the
* backing_hd reference now */
backing_hd_ctx = bdrv_get_aio_context(backing_hd);
aio_context_acquire(backing_hd_ctx);
ret = bdrv_set_backing_hd(bs, backing_hd, errp);
bdrv_unref(backing_hd);
aio_context_release(backing_hd_ctx);
if (ret < 0) {
goto free_exit;
}
qdict_del(parent_options, bdref_key);
free_exit:
g_free(backing_filename);
qobject_unref(tmp_parent_options);
return ret;
}
static BlockDriverState *
bdrv_open_child_bs(const char *filename, QDict *options, const char *bdref_key,
BlockDriverState *parent, const BdrvChildClass *child_class,
BdrvChildRole child_role, bool allow_none, Error **errp)
{
BlockDriverState *bs = NULL;
QDict *image_options;
char *bdref_key_dot;
const char *reference;
assert(child_class != NULL);
bdref_key_dot = g_strdup_printf("%s.", bdref_key);
qdict_extract_subqdict(options, &image_options, bdref_key_dot);
g_free(bdref_key_dot);
/*
* Caution: while qdict_get_try_str() is fine, getting non-string
* types would require more care. When @options come from
* -blockdev or blockdev_add, its members are typed according to
* the QAPI schema, but when they come from -drive, they're all
* QString.
*/
reference = qdict_get_try_str(options, bdref_key);
if (!filename && !reference && !qdict_size(image_options)) {
if (!allow_none) {
error_setg(errp, "A block device must be specified for \"%s\"",
bdref_key);
}
qobject_unref(image_options);
goto done;
}
bs = bdrv_open_inherit(filename, reference, image_options, 0,
parent, child_class, child_role, errp);
if (!bs) {
goto done;
}
done:
qdict_del(options, bdref_key);
return bs;
}
/*
* Opens a disk image whose options are given as BlockdevRef in another block
* device's options.
*
* If allow_none is true, no image will be opened if filename is false and no
* BlockdevRef is given. NULL will be returned, but errp remains unset.
*
* bdrev_key specifies the key for the image's BlockdevRef in the options QDict.
* That QDict has to be flattened; therefore, if the BlockdevRef is a QDict
* itself, all options starting with "${bdref_key}." are considered part of the
* BlockdevRef.
*
* The BlockdevRef will be removed from the options QDict.
*
* The caller must hold the lock of the main AioContext and no other AioContext.
* @parent can move to a different AioContext in this function. Callers must
* make sure that their AioContext locking is still correct after this.
*/
BdrvChild *bdrv_open_child(const char *filename,
QDict *options, const char *bdref_key,
BlockDriverState *parent,
const BdrvChildClass *child_class,
BdrvChildRole child_role,
bool allow_none, Error **errp)
{
BlockDriverState *bs;
BdrvChild *child;
AioContext *ctx;
GLOBAL_STATE_CODE();
bs = bdrv_open_child_bs(filename, options, bdref_key, parent, child_class,
child_role, allow_none, errp);
if (bs == NULL) {
return NULL;
}
bdrv_graph_wrlock(NULL);
ctx = bdrv_get_aio_context(bs);
aio_context_acquire(ctx);
child = bdrv_attach_child(parent, bs, bdref_key, child_class, child_role,
errp);
aio_context_release(ctx);
bdrv_graph_wrunlock();
return child;
}
/*
* Wrapper on bdrv_open_child() for most popular case: open primary child of bs.
*
* The caller must hold the lock of the main AioContext and no other AioContext.
* @parent can move to a different AioContext in this function. Callers must
* make sure that their AioContext locking is still correct after this.
*/
int bdrv_open_file_child(const char *filename,
QDict *options, const char *bdref_key,
BlockDriverState *parent, Error **errp)
{
BdrvChildRole role;
/* commit_top and mirror_top don't use this function */
assert(!parent->drv->filtered_child_is_backing);
role = parent->drv->is_filter ?
(BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY) : BDRV_CHILD_IMAGE;
if (!bdrv_open_child(filename, options, bdref_key, parent,
&child_of_bds, role, false, errp))
{
return -EINVAL;
}
return 0;
}
/*
* TODO Future callers may need to specify parent/child_class in order for
* option inheritance to work. Existing callers use it for the root node.
*/
BlockDriverState *bdrv_open_blockdev_ref(BlockdevRef *ref, Error **errp)
{
BlockDriverState *bs = NULL;
QObject *obj = NULL;
QDict *qdict = NULL;
const char *reference = NULL;
Visitor *v = NULL;
GLOBAL_STATE_CODE();
if (ref->type == QTYPE_QSTRING) {
reference = ref->u.reference;
} else {
BlockdevOptions *options = &ref->u.definition;
assert(ref->type == QTYPE_QDICT);
v = qobject_output_visitor_new(&obj);
visit_type_BlockdevOptions(v, NULL, &options, &error_abort);
visit_complete(v, &obj);
qdict = qobject_to(QDict, obj);
qdict_flatten(qdict);
/* bdrv_open_inherit() defaults to the values in bdrv_flags (for
* compatibility with other callers) rather than what we want as the
* real defaults. Apply the defaults here instead. */
qdict_set_default_str(qdict, BDRV_OPT_CACHE_DIRECT, "off");
qdict_set_default_str(qdict, BDRV_OPT_CACHE_NO_FLUSH, "off");
qdict_set_default_str(qdict, BDRV_OPT_READ_ONLY, "off");
qdict_set_default_str(qdict, BDRV_OPT_AUTO_READ_ONLY, "off");
}
bs = bdrv_open_inherit(NULL, reference, qdict, 0, NULL, NULL, 0, errp);
obj = NULL;
qobject_unref(obj);
visit_free(v);
return bs;
}
static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs,
int flags,
QDict *snapshot_options,
Error **errp)
{
g_autofree char *tmp_filename = NULL;
int64_t total_size;
QemuOpts *opts = NULL;
BlockDriverState *bs_snapshot = NULL;
AioContext *ctx = bdrv_get_aio_context(bs);
int ret;
GLOBAL_STATE_CODE();
/* if snapshot, we create a temporary backing file and open it
instead of opening 'filename' directly */
/* Get the required size from the image */
aio_context_acquire(ctx);
total_size = bdrv_getlength(bs);
aio_context_release(ctx);
if (total_size < 0) {
error_setg_errno(errp, -total_size, "Could not get image size");
goto out;
}
/* Create the temporary image */
tmp_filename = create_tmp_file(errp);
if (!tmp_filename) {
goto out;
}
opts = qemu_opts_create(bdrv_qcow2.create_opts, NULL, 0,
&error_abort);
qemu_opt_set_number(opts, BLOCK_OPT_SIZE, total_size, &error_abort);
ret = bdrv_create(&bdrv_qcow2, tmp_filename, opts, errp);
qemu_opts_del(opts);
if (ret < 0) {
error_prepend(errp, "Could not create temporary overlay '%s': ",
tmp_filename);
goto out;
}
/* Prepare options QDict for the temporary file */
qdict_put_str(snapshot_options, "file.driver", "file");
qdict_put_str(snapshot_options, "file.filename", tmp_filename);
qdict_put_str(snapshot_options, "driver", "qcow2");
bs_snapshot = bdrv_open(NULL, NULL, snapshot_options, flags, errp);
snapshot_options = NULL;
if (!bs_snapshot) {
goto out;
}
aio_context_acquire(ctx);
ret = bdrv_append(bs_snapshot, bs, errp);
aio_context_release(ctx);
if (ret < 0) {
bs_snapshot = NULL;
goto out;
}
out:
qobject_unref(snapshot_options);
return bs_snapshot;
}
/*
* Opens a disk image (raw, qcow2, vmdk, ...)
*
* options is a QDict of options to pass to the block drivers, or NULL for an
* empty set of options. The reference to the QDict belongs to the block layer
* after the call (even on failure), so if the caller intends to reuse the
* dictionary, it needs to use qobject_ref() before calling bdrv_open.
*
* If *pbs is NULL, a new BDS will be created with a pointer to it stored there.
* If it is not NULL, the referenced BDS will be reused.
*
* The reference parameter may be used to specify an existing block device which
* should be opened. If specified, neither options nor a filename may be given,
* nor can an existing BDS be reused (that is, *pbs has to be NULL).
*
* The caller must always hold the main AioContext lock.
*/
static BlockDriverState * no_coroutine_fn
bdrv_open_inherit(const char *filename, const char *reference, QDict *options,
int flags, BlockDriverState *parent,
const BdrvChildClass *child_class, BdrvChildRole child_role,
Error **errp)
{
int ret;
BlockBackend *file = NULL;
BlockDriverState *bs;
BlockDriver *drv = NULL;
BdrvChild *child;
const char *drvname;
const char *backing;
Error *local_err = NULL;
QDict *snapshot_options = NULL;
int snapshot_flags = 0;
AioContext *ctx = qemu_get_aio_context();
assert(!child_class || !flags);
assert(!child_class == !parent);
GLOBAL_STATE_CODE();
assert(!qemu_in_coroutine());
/* TODO We'll eventually have to take a writer lock in this function */
GRAPH_RDLOCK_GUARD_MAINLOOP();
if (reference) {
bool options_non_empty = options ? qdict_size(options) : false;
qobject_unref(options);
if (filename || options_non_empty) {
error_setg(errp, "Cannot reference an existing block device with "
"additional options or a new filename");
return NULL;
}
bs = bdrv_lookup_bs(reference, reference, errp);
if (!bs) {
return NULL;
}
bdrv_ref(bs);
return bs;
}
bs = bdrv_new();
/* NULL means an empty set of options */
if (options == NULL) {
options = qdict_new();
}
/* json: syntax counts as explicit options, as if in the QDict */
parse_json_protocol(options, &filename, &local_err);
if (local_err) {
goto fail;
}
bs->explicit_options = qdict_clone_shallow(options);
if (child_class) {
bool parent_is_format;
if (parent->drv) {
parent_is_format = parent->drv->is_format;
} else {
/*
* parent->drv is not set yet because this node is opened for
* (potential) format probing. That means that @parent is going
* to be a format node.
*/
parent_is_format = true;
}
bs->inherits_from = parent;
child_class->inherit_options(child_role, parent_is_format,
&flags, options,
parent->open_flags, parent->options);
}
ret = bdrv_fill_options(&options, filename, &flags, &local_err);
if (ret < 0) {
goto fail;
}
/*
* Set the BDRV_O_RDWR and BDRV_O_ALLOW_RDWR flags.
* Caution: getting a boolean member of @options requires care.
* When @options come from -blockdev or blockdev_add, members are
* typed according to the QAPI schema, but when they come from
* -drive, they're all QString.
*/
if (g_strcmp0(qdict_get_try_str(options, BDRV_OPT_READ_ONLY), "on") &&
!qdict_get_try_bool(options, BDRV_OPT_READ_ONLY, false)) {
flags |= (BDRV_O_RDWR | BDRV_O_ALLOW_RDWR);
} else {
flags &= ~BDRV_O_RDWR;
}
if (flags & BDRV_O_SNAPSHOT) {
snapshot_options = qdict_new();
bdrv_temp_snapshot_options(&snapshot_flags, snapshot_options,
flags, options);
/* Let bdrv_backing_options() override "read-only" */
qdict_del(options, BDRV_OPT_READ_ONLY);
bdrv_inherited_options(BDRV_CHILD_COW, true,
&flags, options, flags, options);
}
bs->open_flags = flags;
bs->options = options;
options = qdict_clone_shallow(options);
/* Find the right image format driver */
/* See cautionary note on accessing @options above */
drvname = qdict_get_try_str(options, "driver");
if (drvname) {
drv = bdrv_find_format(drvname);
if (!drv) {
error_setg(errp, "Unknown driver: '%s'", drvname);
goto fail;
}
}
assert(drvname || !(flags & BDRV_O_PROTOCOL));
/* See cautionary note on accessing @options above */
backing = qdict_get_try_str(options, "backing");
if (qobject_to(QNull, qdict_get(options, "backing")) != NULL ||
(backing && *backing == '\0'))
{
if (backing) {
warn_report("Use of \"backing\": \"\" is deprecated; "
"use \"backing\": null instead");
}
flags |= BDRV_O_NO_BACKING;
qdict_del(bs->explicit_options, "backing");
qdict_del(bs->options, "backing");
qdict_del(options, "backing");
}
/* Open image file without format layer. This BlockBackend is only used for
* probing, the block drivers will do their own bdrv_open_child() for the
* same BDS, which is why we put the node name back into options. */
if ((flags & BDRV_O_PROTOCOL) == 0) {
BlockDriverState *file_bs;
file_bs = bdrv_open_child_bs(filename, options, "file", bs,
&child_of_bds, BDRV_CHILD_IMAGE,
true, &local_err);
if (local_err) {
goto fail;
}
if (file_bs != NULL) {
/* Not requesting BLK_PERM_CONSISTENT_READ because we're only
* looking at the header to guess the image format. This works even
* in cases where a guest would not see a consistent state. */
ctx = bdrv_get_aio_context(file_bs);
aio_context_acquire(ctx);
file = blk_new(ctx, 0, BLK_PERM_ALL);
blk_insert_bs(file, file_bs, &local_err);
bdrv_unref(file_bs);
aio_context_release(ctx);
if (local_err) {
goto fail;
}
qdict_put_str(options, "file", bdrv_get_node_name(file_bs));
}
}
/* Image format probing */
bs->probed = !drv;
if (!drv && file) {
ret = find_image_format(file, filename, &drv, &local_err);
if (ret < 0) {
goto fail;
}
/*
* This option update would logically belong in bdrv_fill_options(),
* but we first need to open bs->file for the probing to work, while
* opening bs->file already requires the (mostly) final set of options
* so that cache mode etc. can be inherited.
*
* Adding the driver later is somewhat ugly, but it's not an option
* that would ever be inherited, so it's correct. We just need to make
* sure to update both bs->options (which has the full effective
* options for bs) and options (which has file.* already removed).
*/
qdict_put_str(bs->options, "driver", drv->format_name);
qdict_put_str(options, "driver", drv->format_name);
} else if (!drv) {
error_setg(errp, "Must specify either driver or file");
goto fail;
}
/* BDRV_O_PROTOCOL must be set iff a protocol BDS is about to be created */
assert(!!(flags & BDRV_O_PROTOCOL) == !!drv->bdrv_file_open);
/* file must be NULL if a protocol BDS is about to be created
* (the inverse results in an error message from bdrv_open_common()) */
assert(!(flags & BDRV_O_PROTOCOL) || !file);
/* Open the image */
ret = bdrv_open_common(bs, file, options, &local_err);
if (ret < 0) {
goto fail;
}
/* The AioContext could have changed during bdrv_open_common() */
ctx = bdrv_get_aio_context(bs);
if (file) {
aio_context_acquire(ctx);
blk_unref(file);
aio_context_release(ctx);
file = NULL;
}
/* If there is a backing file, use it */
if ((flags & BDRV_O_NO_BACKING) == 0) {
ret = bdrv_open_backing_file(bs, options, "backing", &local_err);
if (ret < 0) {
goto close_and_fail;
}
}
/* Remove all children options and references
* from bs->options and bs->explicit_options */
QLIST_FOREACH(child, &bs->children, next) {
char *child_key_dot;
child_key_dot = g_strdup_printf("%s.", child->name);
qdict_extract_subqdict(bs->explicit_options, NULL, child_key_dot);
qdict_extract_subqdict(bs->options, NULL, child_key_dot);
qdict_del(bs->explicit_options, child->name);
qdict_del(bs->options, child->name);
g_free(child_key_dot);
}
/* Check if any unknown options were used */
if (qdict_size(options) != 0) {
const QDictEntry *entry = qdict_first(options);
if (flags & BDRV_O_PROTOCOL) {
error_setg(errp, "Block protocol '%s' doesn't support the option "
"'%s'", drv->format_name, entry->key);
} else {
error_setg(errp,
"Block format '%s' does not support the option '%s'",
drv->format_name, entry->key);
}
goto close_and_fail;
}
bdrv_parent_cb_change_media(bs, true);
qobject_unref(options);
options = NULL;
/* For snapshot=on, create a temporary qcow2 overlay. bs points to the
* temporary snapshot afterwards. */
if (snapshot_flags) {
BlockDriverState *snapshot_bs;
snapshot_bs = bdrv_append_temp_snapshot(bs, snapshot_flags,
snapshot_options, &local_err);
snapshot_options = NULL;
if (local_err) {
goto close_and_fail;
}
/* We are not going to return bs but the overlay on top of it
* (snapshot_bs); thus, we have to drop the strong reference to bs
* (which we obtained by calling bdrv_new()). bs will not be deleted,
* though, because the overlay still has a reference to it. */
aio_context_acquire(ctx);
bdrv_unref(bs);
aio_context_release(ctx);
bs = snapshot_bs;
}
return bs;
fail:
aio_context_acquire(ctx);
blk_unref(file);
qobject_unref(snapshot_options);
qobject_unref(bs->explicit_options);
qobject_unref(bs->options);
qobject_unref(options);
bs->options = NULL;
bs->explicit_options = NULL;
bdrv_unref(bs);
aio_context_release(ctx);
error_propagate(errp, local_err);
return NULL;
close_and_fail:
aio_context_acquire(ctx);
bdrv_unref(bs);
aio_context_release(ctx);
qobject_unref(snapshot_options);
qobject_unref(options);
error_propagate(errp, local_err);
return NULL;
}
/* The caller must always hold the main AioContext lock. */
BlockDriverState *bdrv_open(const char *filename, const char *reference,
QDict *options, int flags, Error **errp)
{
GLOBAL_STATE_CODE();
return bdrv_open_inherit(filename, reference, options, flags, NULL,
NULL, 0, errp);
}
/* Return true if the NULL-terminated @list contains @str */
static bool is_str_in_list(const char *str, const char *const *list)
{
if (str && list) {
int i;
for (i = 0; list[i] != NULL; i++) {
if (!strcmp(str, list[i])) {
return true;
}
}
}
return false;
}
/*
* Check that every option set in @bs->options is also set in
* @new_opts.
*
* Options listed in the common_options list and in
* @bs->drv->mutable_opts are skipped.
*
* Return 0 on success, otherwise return -EINVAL and set @errp.
*/
static int bdrv_reset_options_allowed(BlockDriverState *bs,
const QDict *new_opts, Error **errp)
{
const QDictEntry *e;
/* These options are common to all block drivers and are handled
* in bdrv_reopen_prepare() so they can be left out of @new_opts */
const char *const common_options[] = {
"node-name", "discard", "cache.direct", "cache.no-flush",
"read-only", "auto-read-only", "detect-zeroes", NULL
};
for (e = qdict_first(bs->options); e; e = qdict_next(bs->options, e)) {
if (!qdict_haskey(new_opts, e->key) &&
!is_str_in_list(e->key, common_options) &&
!is_str_in_list(e->key, bs->drv->mutable_opts)) {
error_setg(errp, "Option '%s' cannot be reset "
"to its default value", e->key);
return -EINVAL;
}
}
return 0;
}
/*
* Returns true if @child can be reached recursively from @bs
*/
static bool GRAPH_RDLOCK
bdrv_recurse_has_child(BlockDriverState *bs, BlockDriverState *child)
{
BdrvChild *c;
if (bs == child) {
return true;
}
QLIST_FOREACH(c, &bs->children, next) {
if (bdrv_recurse_has_child(c->bs, child)) {
return true;
}
}
return false;
}
/*
* Adds a BlockDriverState to a simple queue for an atomic, transactional
* reopen of multiple devices.
*
* bs_queue can either be an existing BlockReopenQueue that has had QTAILQ_INIT
* already performed, or alternatively may be NULL a new BlockReopenQueue will
* be created and initialized. This newly created BlockReopenQueue should be
* passed back in for subsequent calls that are intended to be of the same
* atomic 'set'.
*
* bs is the BlockDriverState to add to the reopen queue.
*
* options contains the changed options for the associated bs
* (the BlockReopenQueue takes ownership)
*
* flags contains the open flags for the associated bs
*
* returns a pointer to bs_queue, which is either the newly allocated
* bs_queue, or the existing bs_queue being used.
*
* bs is drained here and undrained by bdrv_reopen_queue_free().
*
* To be called with bs->aio_context locked.
*/
static BlockReopenQueue * GRAPH_RDLOCK
bdrv_reopen_queue_child(BlockReopenQueue *bs_queue, BlockDriverState *bs,
QDict *options, const BdrvChildClass *klass,
BdrvChildRole role, bool parent_is_format,
QDict *parent_options, int parent_flags,
bool keep_old_opts)
{
assert(bs != NULL);
BlockReopenQueueEntry *bs_entry;
BdrvChild *child;
QDict *old_options, *explicit_options, *options_copy;
int flags;
QemuOpts *opts;
GLOBAL_STATE_CODE();
/*
* Strictly speaking, draining is illegal under GRAPH_RDLOCK. We know that
* we've been called with bdrv_graph_rdlock_main_loop(), though, so it's ok
* in practice.
*/
bdrv_drained_begin(bs);
if (bs_queue == NULL) {
bs_queue = g_new0(BlockReopenQueue, 1);
QTAILQ_INIT(bs_queue);
}
if (!options) {
options = qdict_new();
}
/* Check if this BlockDriverState is already in the queue */
QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
if (bs == bs_entry->state.bs) {
break;
}
}
/*
* Precedence of options:
* 1. Explicitly passed in options (highest)
* 2. Retained from explicitly set options of bs
* 3. Inherited from parent node
* 4. Retained from effective options of bs
*/
/* Old explicitly set values (don't overwrite by inherited value) */
if (bs_entry || keep_old_opts) {
old_options = qdict_clone_shallow(bs_entry ?
bs_entry->state.explicit_options :
bs->explicit_options);
bdrv_join_options(bs, options, old_options);
qobject_unref(old_options);
}
explicit_options = qdict_clone_shallow(options);
/* Inherit from parent node */
if (parent_options) {
flags = 0;
klass->inherit_options(role, parent_is_format, &flags, options,
parent_flags, parent_options);
} else {
flags = bdrv_get_flags(bs);
}
if (keep_old_opts) {
/* Old values are used for options that aren't set yet */
old_options = qdict_clone_shallow(bs->options);
bdrv_join_options(bs, options, old_options);
qobject_unref(old_options);
}
/* We have the final set of options so let's update the flags */
options_copy = qdict_clone_shallow(options);
opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort);
qemu_opts_absorb_qdict(opts, options_copy, NULL);
update_flags_from_options(&flags, opts);
qemu_opts_del(opts);
qobject_unref(options_copy);
/* bdrv_open_inherit() sets and clears some additional flags internally */
flags &= ~BDRV_O_PROTOCOL;
if (flags & BDRV_O_RDWR) {
flags |= BDRV_O_ALLOW_RDWR;
}
if (!bs_entry) {
bs_entry = g_new0(BlockReopenQueueEntry, 1);
QTAILQ_INSERT_TAIL(bs_queue, bs_entry, entry);
} else {
qobject_unref(bs_entry->state.options);
qobject_unref(bs_entry->state.explicit_options);
}
bs_entry->state.bs = bs;
bs_entry->state.options = options;
bs_entry->state.explicit_options = explicit_options;
bs_entry->state.flags = flags;
/*
* If keep_old_opts is false then it means that unspecified
* options must be reset to their original value. We don't allow
* resetting 'backing' but we need to know if the option is
* missing in order to decide if we have to return an error.
*/
if (!keep_old_opts) {
bs_entry->state.backing_missing =
!qdict_haskey(options, "backing") &&
!qdict_haskey(options, "backing.driver");
}
QLIST_FOREACH(child, &bs->children, next) {
QDict *new_child_options = NULL;
bool child_keep_old = keep_old_opts;
/* reopen can only change the options of block devices that were
* implicitly created and inherited options. For other (referenced)
* block devices, a syntax like "backing.foo" results in an error. */
if (child->bs->inherits_from != bs) {
continue;
}
/* Check if the options contain a child reference */
if (qdict_haskey(options, child->name)) {
const char *childref = qdict_get_try_str(options, child->name);
/*
* The current child must not be reopened if the child
* reference is null or points to a different node.
*/
if (g_strcmp0(childref, child->bs->node_name)) {
continue;
}
/*
* If the child reference points to the current child then
* reopen it with its existing set of options (note that
* it can still inherit new options from the parent).
*/
child_keep_old = true;
} else {
/* Extract child options ("child-name.*") */
char *child_key_dot = g_strdup_printf("%s.", child->name);
qdict_extract_subqdict(explicit_options, NULL, child_key_dot);
qdict_extract_subqdict(options, &new_child_options, child_key_dot);
g_free(child_key_dot);
}
bdrv_reopen_queue_child(bs_queue, child->bs, new_child_options,
child->klass, child->role, bs->drv->is_format,
options, flags, child_keep_old);
}
return bs_queue;
}
/* To be called with bs->aio_context locked */
BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue *bs_queue,
BlockDriverState *bs,
QDict *options, bool keep_old_opts)
{
GLOBAL_STATE_CODE();
GRAPH_RDLOCK_GUARD_MAINLOOP();
return bdrv_reopen_queue_child(bs_queue, bs, options, NULL, 0, false,
NULL, 0, keep_old_opts);
}
void bdrv_reopen_queue_free(BlockReopenQueue *bs_queue)
{
GLOBAL_STATE_CODE();
if (bs_queue) {
BlockReopenQueueEntry *bs_entry, *next;
QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) {
AioContext *ctx = bdrv_get_aio_context(bs_entry->state.bs);
aio_context_acquire(ctx);
bdrv_drained_end(bs_entry->state.bs);
aio_context_release(ctx);
qobject_unref(bs_entry->state.explicit_options);
qobject_unref(bs_entry->state.options);
g_free(bs_entry);
}
g_free(bs_queue);
}
}
/*
* Reopen multiple BlockDriverStates atomically & transactionally.
*
* The queue passed in (bs_queue) must have been built up previous
* via bdrv_reopen_queue().
*
* Reopens all BDS specified in the queue, with the appropriate
* flags. All devices are prepared for reopen, and failure of any
* device will cause all device changes to be abandoned, and intermediate
* data cleaned up.
*
* If all devices prepare successfully, then the changes are committed
* to all devices.
*
* All affected nodes must be drained between bdrv_reopen_queue() and
* bdrv_reopen_multiple().
*
* To be called from the main thread, with all other AioContexts unlocked.
*/
int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp)
{
int ret = -1;
BlockReopenQueueEntry *bs_entry, *next;
AioContext *ctx;
Transaction *tran = tran_new();
g_autoptr(GSList) refresh_list = NULL;
assert(qemu_get_current_aio_context() == qemu_get_aio_context());
assert(bs_queue != NULL);
GLOBAL_STATE_CODE();
QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
ctx = bdrv_get_aio_context(bs_entry->state.bs);
aio_context_acquire(ctx);
ret = bdrv_flush(bs_entry->state.bs);
aio_context_release(ctx);
if (ret < 0) {
error_setg_errno(errp, -ret, "Error flushing drive");
goto abort;
}
}
QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
assert(bs_entry->state.bs->quiesce_counter > 0);
ctx = bdrv_get_aio_context(bs_entry->state.bs);
aio_context_acquire(ctx);
ret = bdrv_reopen_prepare(&bs_entry->state, bs_queue, tran, errp);
aio_context_release(ctx);
if (ret < 0) {
goto abort;
}
bs_entry->prepared = true;
}
QTAILQ_FOREACH(bs_entry, bs_queue, entry) {
BDRVReopenState *state = &bs_entry->state;
refresh_list = g_slist_prepend(refresh_list, state->bs);
if (state->old_backing_bs) {
refresh_list = g_slist_prepend(refresh_list, state->old_backing_bs);
}
if (state->old_file_bs) {
refresh_list = g_slist_prepend(refresh_list, state->old_file_bs);
}
}
/*
* Note that file-posix driver rely on permission update done during reopen
* (even if no permission changed), because it wants "new" permissions for
* reconfiguring the fd and that's why it does it in raw_check_perm(), not
* in raw_reopen_prepare() which is called with "old" permissions.
*/
bdrv_graph_rdlock_main_loop();
ret = bdrv_list_refresh_perms(refresh_list, bs_queue, tran, errp);
bdrv_graph_rdunlock_main_loop();
if (ret < 0) {
goto abort;
}
/*
* If we reach this point, we have success and just need to apply the
* changes.
*
* Reverse order is used to comfort qcow2 driver: on commit it need to write
* IN_USE flag to the image, to mark bitmaps in the image as invalid. But
* children are usually goes after parents in reopen-queue, so go from last
* to first element.
*/
QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) {
ctx = bdrv_get_aio_context(bs_entry->state.bs);
aio_context_acquire(ctx);
bdrv_reopen_commit(&bs_entry->state);
aio_context_release(ctx);
}
bdrv_graph_wrlock(NULL);
tran_commit(tran);
bdrv_graph_wrunlock();
QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) {
BlockDriverState *bs = bs_entry->state.bs;
if (bs->drv->bdrv_reopen_commit_post) {
ctx = bdrv_get_aio_context(bs);
aio_context_acquire(ctx);
bs->drv->bdrv_reopen_commit_post(&bs_entry->state);
aio_context_release(ctx);
}
}
ret = 0;
goto cleanup;
abort:
bdrv_graph_wrlock(NULL);
tran_abort(tran);
bdrv_graph_wrunlock();
QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) {
if (bs_entry->prepared) {
ctx = bdrv_get_aio_context(bs_entry->state.bs);
aio_context_acquire(ctx);
bdrv_reopen_abort(&bs_entry->state);
aio_context_release(ctx);
}
}
cleanup:
bdrv_reopen_queue_free(bs_queue);
return ret;
}
int bdrv_reopen(BlockDriverState *bs, QDict *opts, bool keep_old_opts,
Error **errp)
{
AioContext *ctx = bdrv_get_aio_context(bs);
BlockReopenQueue *queue;
int ret;
GLOBAL_STATE_CODE();
queue = bdrv_reopen_queue(NULL, bs, opts, keep_old_opts);
if (ctx != qemu_get_aio_context()) {
aio_context_release(ctx);
}
ret = bdrv_reopen_multiple(queue, errp);
if (ctx != qemu_get_aio_context()) {
aio_context_acquire(ctx);
}
return ret;
}
int bdrv_reopen_set_read_only(BlockDriverState *bs, bool read_only,
Error **errp)
{
QDict *opts = qdict_new();
GLOBAL_STATE_CODE();
qdict_put_bool(opts, BDRV_OPT_READ_ONLY, read_only);
return bdrv_reopen(bs, opts, true, errp);
}
/*
* Take a BDRVReopenState and check if the value of 'backing' in the
* reopen_state->options QDict is valid or not.
*
* If 'backing' is missing from the QDict then return 0.
*
* If 'backing' contains the node name of the backing file of
* reopen_state->bs then return 0.
*
* If 'backing' contains a different node name (or is null) then check
* whether the current backing file can be replaced with the new one.
* If that's the case then reopen_state->replace_backing_bs is set to
* true and reopen_state->new_backing_bs contains a pointer to the new
* backing BlockDriverState (or NULL).
*
* After calling this function, the transaction @tran may only be completed
* while holding a writer lock for the graph.
*
* Return 0 on success, otherwise return < 0 and set @errp.
*
* The caller must hold the AioContext lock of @reopen_state->bs.
* @reopen_state->bs can move to a different AioContext in this function.
* Callers must make sure that their AioContext locking is still correct after
* this.
*/
static int GRAPH_UNLOCKED
bdrv_reopen_parse_file_or_backing(BDRVReopenState *reopen_state,
bool is_backing, Transaction *tran,
Error **errp)
{
BlockDriverState *bs = reopen_state->bs;
BlockDriverState *new_child_bs;
BlockDriverState *old_child_bs;
const char *child_name = is_backing ? "backing" : "file";
QObject *value;
const char *str;
AioContext *ctx, *old_ctx;
bool has_child;
int ret;
GLOBAL_STATE_CODE();
value = qdict_get(reopen_state->options, child_name);
if (value == NULL) {
return 0;
}
bdrv_graph_rdlock_main_loop();
switch (qobject_type(value)) {
case QTYPE_QNULL:
assert(is_backing); /* The 'file' option does not allow a null value */
new_child_bs = NULL;
break;
case QTYPE_QSTRING:
str = qstring_get_str(qobject_to(QString, value));
new_child_bs = bdrv_lookup_bs(NULL, str, errp);
if (new_child_bs == NULL) {
ret = -EINVAL;
goto out_rdlock;
}
has_child = bdrv_recurse_has_child(new_child_bs, bs);
if (has_child) {
error_setg(errp, "Making '%s' a %s child of '%s' would create a "
"cycle", str, child_name, bs->node_name);
ret = -EINVAL;
goto out_rdlock;
}
break;
default:
/*
* The options QDict has been flattened, so 'backing' and 'file'
* do not allow any other data type here.
*/
g_assert_not_reached();
}
old_child_bs = is_backing ? child_bs(bs->backing) : child_bs(bs->file);
if (old_child_bs == new_child_bs) {
ret = 0;
goto out_rdlock;
}
if (old_child_bs) {
if (bdrv_skip_implicit_filters(old_child_bs) == new_child_bs) {
ret = 0;
goto out_rdlock;
}
if (old_child_bs->implicit) {
error_setg(errp, "Cannot replace implicit %s child of %s",
child_name, bs->node_name);
ret = -EPERM;
goto out_rdlock;
}
}
if (bs->drv->is_filter && !old_child_bs) {
/*
* Filters always have a file or a backing child, so we are trying to
* change wrong child
*/
error_setg(errp, "'%s' is a %s filter node that does not support a "
"%s child", bs->node_name, bs->drv->format_name, child_name);
ret = -EINVAL;
goto out_rdlock;
}
if (is_backing) {
reopen_state->old_backing_bs = old_child_bs;
} else {
reopen_state->old_file_bs = old_child_bs;
}
if (old_child_bs) {
bdrv_ref(old_child_bs);
bdrv_drained_begin(old_child_bs);
}
old_ctx = bdrv_get_aio_context(bs);
ctx = bdrv_get_aio_context(new_child_bs);
if (old_ctx != ctx) {
aio_context_release(old_ctx);
aio_context_acquire(ctx);
}
bdrv_graph_rdunlock_main_loop();
bdrv_graph_wrlock(new_child_bs);
ret = bdrv_set_file_or_backing_noperm(bs, new_child_bs, is_backing,
tran, errp);
bdrv_graph_wrunlock();
if (old_ctx != ctx) {
aio_context_release(ctx);
aio_context_acquire(old_ctx);
}
if (old_child_bs) {
bdrv_drained_end(old_child_bs);
bdrv_unref(old_child_bs);
}
return ret;
out_rdlock:
bdrv_graph_rdunlock_main_loop();
return ret;
}
/*
* Prepares a BlockDriverState for reopen. All changes are staged in the
* 'opaque' field of the BDRVReopenState, which is used and allocated by
* the block driver layer .bdrv_reopen_prepare()
*
* bs is the BlockDriverState to reopen
* flags are the new open flags
* queue is the reopen queue
*
* Returns 0 on success, non-zero on error. On error errp will be set
* as well.
*
* On failure, bdrv_reopen_abort() will be called to clean up any data.
* It is the responsibility of the caller to then call the abort() or
* commit() for any other BDS that have been left in a prepare() state
*
* The caller must hold the AioContext lock of @reopen_state->bs.
*
* After calling this function, the transaction @change_child_tran may only be
* completed while holding a writer lock for the graph.
*/
static int GRAPH_UNLOCKED
bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue,
Transaction *change_child_tran, Error **errp)
{
int ret = -1;
int old_flags;
Error *local_err = NULL;
BlockDriver *drv;
QemuOpts *opts;
QDict *orig_reopen_opts;
char *discard = NULL;
bool read_only;
bool drv_prepared = false;
assert(reopen_state != NULL);
assert(reopen_state->bs->drv != NULL);
GLOBAL_STATE_CODE();
drv = reopen_state->bs->drv;
/* This function and each driver's bdrv_reopen_prepare() remove
* entries from reopen_state->options as they are processed, so
* we need to make a copy of the original QDict. */
orig_reopen_opts = qdict_clone_shallow(reopen_state->options);
/* Process generic block layer options */
opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort);
if (!qemu_opts_absorb_qdict(opts, reopen_state->options, errp)) {
ret = -EINVAL;
goto error;
}
/* This was already called in bdrv_reopen_queue_child() so the flags
* are up-to-date. This time we simply want to remove the options from
* QemuOpts in order to indicate that they have been processed. */
old_flags = reopen_state->flags;
update_flags_from_options(&reopen_state->flags, opts);
assert(old_flags == reopen_state->flags);
discard = qemu_opt_get_del(opts, BDRV_OPT_DISCARD);
if (discard != NULL) {
if (bdrv_parse_discard_flags(discard, &reopen_state->flags) != 0) {
error_setg(errp, "Invalid discard option");
ret = -EINVAL;
goto error;
}
}
reopen_state->detect_zeroes =
bdrv_parse_detect_zeroes(opts, reopen_state->flags, &local_err);
if (local_err) {
error_propagate(errp, local_err);
ret = -EINVAL;
goto error;
}
/* All other options (including node-name and driver) must be unchanged.
* Put them back into the QDict, so that they are checked at the end
* of this function. */
qemu_opts_to_qdict(opts, reopen_state->options);
/* If we are to stay read-only, do not allow permission change
* to r/w. Attempting to set to r/w may fail if either BDRV_O_ALLOW_RDWR is
* not set, or if the BDS still has copy_on_read enabled */
read_only = !(reopen_state->flags & BDRV_O_RDWR);
bdrv_graph_rdlock_main_loop();
ret = bdrv_can_set_read_only(reopen_state->bs, read_only, true, &local_err);
bdrv_graph_rdunlock_main_loop();
if (local_err) {
error_propagate(errp, local_err);
goto error;
}
if (drv->bdrv_reopen_prepare) {
/*
* If a driver-specific option is missing, it means that we
* should reset it to its default value.
* But not all options allow that, so we need to check it first.
*/
ret = bdrv_reset_options_allowed(reopen_state->bs,
reopen_state->options, errp);
if (ret) {
goto error;
}
ret = drv->bdrv_reopen_prepare(reopen_state, queue, &local_err);
if (ret) {
if (local_err != NULL) {
error_propagate(errp, local_err);
} else {
bdrv_graph_rdlock_main_loop();
bdrv_refresh_filename(reopen_state->bs);
bdrv_graph_rdunlock_main_loop();
error_setg(errp, "failed while preparing to reopen image '%s'",
reopen_state->bs->filename);
}
goto error;
}
} else {
/* It is currently mandatory to have a bdrv_reopen_prepare()
* handler for each supported drv. */
bdrv_graph_rdlock_main_loop();
error_setg(errp, "Block format '%s' used by node '%s' "
"does not support reopening files", drv->format_name,
bdrv_get_device_or_node_name(reopen_state->bs));
bdrv_graph_rdunlock_main_loop();
ret = -1;
goto error;
}
drv_prepared = true;
/*
* We must provide the 'backing' option if the BDS has a backing
* file or if the image file has a backing file name as part of
* its metadata. Otherwise the 'backing' option can be omitted.
*/
bdrv_graph_rdlock_main_loop();
if (drv->supports_backing && reopen_state->backing_missing &&
(reopen_state->bs->backing || reopen_state->bs->backing_file[0])) {
error_setg(errp, "backing is missing for '%s'",
reopen_state->bs->node_name);
bdrv_graph_rdunlock_main_loop();
ret = -EINVAL;
goto error;
}
bdrv_graph_rdunlock_main_loop();
/*
* Allow changing the 'backing' option. The new value can be
* either a reference to an existing node (using its node name)
* or NULL to simply detach the current backing file.
*/
ret = bdrv_reopen_parse_file_or_backing(reopen_state, true,
change_child_tran, errp);
if (ret < 0) {
goto error;
}
qdict_del(reopen_state->options, "backing");
/* Allow changing the 'file' option. In this case NULL is not allowed */
ret = bdrv_reopen_parse_file_or_backing(reopen_state, false,
change_child_tran, errp);
if (ret < 0) {
goto error;
}
qdict_del(reopen_state->options, "file");
/* Options that are not handled are only okay if they are unchanged
* compared to the old state. It is expected that some options are only
* used for the initial open, but not reopen (e.g. filename) */
if (qdict_size(reopen_state->options)) {
const QDictEntry *entry = qdict_first(reopen_state->options);
GRAPH_RDLOCK_GUARD_MAINLOOP();
do {
QObject *new = entry->value;
QObject *old = qdict_get(reopen_state->bs->options, entry->key);
/* Allow child references (child_name=node_name) as long as they
* point to the current child (i.e. everything stays the same). */
if (qobject_type(new) == QTYPE_QSTRING) {
BdrvChild *child;
QLIST_FOREACH(child, &reopen_state->bs->children, next) {
if (!strcmp(child->name, entry->key)) {
break;
}
}
if (child) {
if (!strcmp(child->bs->node_name,
qstring_get_str(qobject_to(QString, new)))) {
continue; /* Found child with this name, skip option */
}
}
}
/*
* TODO: When using -drive to specify blockdev options, all values
* will be strings; however, when using -blockdev, blockdev-add or
* filenames using the json:{} pseudo-protocol, they will be
* correctly typed.
* In contrast, reopening options are (currently) always strings
* (because you can only specify them through qemu-io; all other
* callers do not specify any options).
* Therefore, when using anything other than -drive to create a BDS,
* this cannot detect non-string options as unchanged, because
* qobject_is_equal() always returns false for objects of different
* type. In the future, this should be remedied by correctly typing
* all options. For now, this is not too big of an issue because
* the user can simply omit options which cannot be changed anyway,
* so they will stay unchanged.
*/
if (!qobject_is_equal(new, old)) {
error_setg(errp, "Cannot change the option '%s'", entry->key);
ret = -EINVAL;
goto error;
}
} while ((entry = qdict_next(reopen_state->options, entry)));
}
ret = 0;
/* Restore the original reopen_state->options QDict */
qobject_unref(reopen_state->options);
reopen_state->options = qobject_ref(orig_reopen_opts);
error:
if (ret < 0 && drv_prepared) {
/* drv->bdrv_reopen_prepare() has succeeded, so we need to
* call drv->bdrv_reopen_abort() before signaling an error
* (bdrv_reopen_multiple() will not call bdrv_reopen_abort()
* when the respective bdrv_reopen_prepare() has failed) */
if (drv->bdrv_reopen_abort) {
drv->bdrv_reopen_abort(reopen_state);
}
}
qemu_opts_del(opts);
qobject_unref(orig_reopen_opts);
g_free(discard);
return ret;
}
/*
* Takes the staged changes for the reopen from bdrv_reopen_prepare(), and
* makes them final by swapping the staging BlockDriverState contents into
* the active BlockDriverState contents.
*/
static void GRAPH_UNLOCKED bdrv_reopen_commit(BDRVReopenState *reopen_state)
{
BlockDriver *drv;
BlockDriverState *bs;
BdrvChild *child;
assert(reopen_state != NULL);
bs = reopen_state->bs;
drv = bs->drv;
assert(drv != NULL);
GLOBAL_STATE_CODE();
/* If there are any driver level actions to take */
if (drv->bdrv_reopen_commit) {
drv->bdrv_reopen_commit(reopen_state);
}
GRAPH_RDLOCK_GUARD_MAINLOOP();
/* set BDS specific flags now */
qobject_unref(bs->explicit_options);
qobject_unref(bs->options);
qobject_ref(reopen_state->explicit_options);
qobject_ref(reopen_state->options);
bs->explicit_options = reopen_state->explicit_options;
bs->options = reopen_state->options;
bs->open_flags = reopen_state->flags;
bs->detect_zeroes = reopen_state->detect_zeroes;
/* Remove child references from bs->options and bs->explicit_options.
* Child options were already removed in bdrv_reopen_queue_child() */
QLIST_FOREACH(child, &bs->children, next) {
qdict_del(bs->explicit_options, child->name);
qdict_del(bs->options, child->name);
}
/* backing is probably removed, so it's not handled by previous loop */
qdict_del(bs->explicit_options, "backing");
qdict_del(bs->options, "backing");
bdrv_refresh_limits(bs, NULL, NULL);
bdrv_refresh_total_sectors(bs, bs->total_sectors);
}
/*
* Abort the reopen, and delete and free the staged changes in
* reopen_state
*/
static void GRAPH_UNLOCKED bdrv_reopen_abort(BDRVReopenState *reopen_state)
{
BlockDriver *drv;
assert(reopen_state != NULL);
drv = reopen_state->bs->drv;
assert(drv != NULL);
GLOBAL_STATE_CODE();
if (drv->bdrv_reopen_abort) {
drv->bdrv_reopen_abort(reopen_state);
}
}
static void bdrv_close(BlockDriverState *bs)
{
BdrvAioNotifier *ban, *ban_next;
BdrvChild *child, *next;
GLOBAL_STATE_CODE();
assert(!bs->refcnt);
bdrv_drained_begin(bs); /* complete I/O */
bdrv_flush(bs);
bdrv_drain(bs); /* in case flush left pending I/O */
if (bs->drv) {
if (bs->drv->bdrv_close) {
/* Must unfreeze all children, so bdrv_unref_child() works */
bs->drv->bdrv_close(bs);
}
bs->drv = NULL;
}
bdrv_graph_wrlock(bs);
QLIST_FOREACH_SAFE(child, &bs->children, next, next) {
bdrv_unref_child(bs, child);
}
assert(!bs->backing);
assert(!bs->file);
bdrv_graph_wrunlock();
g_free(bs->opaque);
bs->opaque = NULL;
qatomic_set(&bs->copy_on_read, 0);
bs->backing_file[0] = '\0';
bs->backing_format[0] = '\0';
bs->total_sectors = 0;
bs->encrypted = false;
bs->sg = false;
qobject_unref(bs->options);
qobject_unref(bs->explicit_options);
bs->options = NULL;
bs->explicit_options = NULL;
qobject_unref(bs->full_open_options);
bs->full_open_options = NULL;
g_free(bs->block_status_cache);
bs->block_status_cache = NULL;
bdrv_release_named_dirty_bitmaps(bs);
assert(QLIST_EMPTY(&bs->dirty_bitmaps));
QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) {
g_free(ban);
}
QLIST_INIT(&bs->aio_notifiers);
bdrv_drained_end(bs);
/*
* If we're still inside some bdrv_drain_all_begin()/end() sections, end
* them now since this BDS won't exist anymore when bdrv_drain_all_end()
* gets called.
*/
if (bs->quiesce_counter) {
bdrv_drain_all_end_quiesce(bs);
}
}
void bdrv_close_all(void)
{
GLOBAL_STATE_CODE();
assert(job_next(NULL) == NULL);
/* Drop references from requests still in flight, such as canceled block
* jobs whose AIO context has not been polled yet */
bdrv_drain_all();
blk_remove_all_bs();
blockdev_close_all_bdrv_states();
assert(QTAILQ_EMPTY(&all_bdrv_states));
}
static bool GRAPH_RDLOCK should_update_child(BdrvChild *c, BlockDriverState *to)
{
GQueue *queue;
GHashTable *found;
bool ret;
if (c->klass->stay_at_node) {
return false;
}
/* If the child @c belongs to the BDS @to, replacing the current
* c->bs by @to would mean to create a loop.
*
* Such a case occurs when appending a BDS to a backing chain.
* For instance, imagine the following chain:
*
* guest device -> node A -> further backing chain...
*
* Now we create a new BDS B which we want to put on top of this
* chain, so we first attach A as its backing node:
*
* node B
* |
* v
* guest device -> node A -> further backing chain...
*
* Finally we want to replace A by B. When doing that, we want to
* replace all pointers to A by pointers to B -- except for the
* pointer from B because (1) that would create a loop, and (2)
* that pointer should simply stay intact:
*
* guest device -> node B
* |
* v
* node A -> further backing chain...
*
* In general, when replacing a node A (c->bs) by a node B (@to),
* if A is a child of B, that means we cannot replace A by B there
* because that would create a loop. Silently detaching A from B
* is also not really an option. So overall just leaving A in
* place there is the most sensible choice.
*
* We would also create a loop in any cases where @c is only
* indirectly referenced by @to. Prevent this by returning false
* if @c is found (by breadth-first search) anywhere in the whole
* subtree of @to.
*/
ret = true;
found = g_hash_table_new(NULL, NULL);
g_hash_table_add(found, to);
queue = g_queue_new();
g_queue_push_tail(queue, to);
while (!g_queue_is_empty(queue)) {
BlockDriverState *v = g_queue_pop_head(queue);
BdrvChild *c2;
QLIST_FOREACH(c2, &v->children, next) {
if (c2 == c) {
ret = false;
break;
}
if (g_hash_table_contains(found, c2->bs)) {
continue;
}
g_queue_push_tail(queue, c2->bs);
g_hash_table_add(found, c2->bs);
}
}
g_queue_free(queue);
g_hash_table_destroy(found);
return ret;
}
static void bdrv_remove_child_commit(void *opaque)
{
GLOBAL_STATE_CODE();
bdrv_child_free(opaque);
}
static TransactionActionDrv bdrv_remove_child_drv = {
.commit = bdrv_remove_child_commit,
};
/*
* Function doesn't update permissions, caller is responsible for this.
*
* @child->bs (if non-NULL) must be drained.
*
* After calling this function, the transaction @tran may only be completed
* while holding a writer lock for the graph.
*/
static void GRAPH_WRLOCK bdrv_remove_child(BdrvChild *child, Transaction *tran)
{
if (!child) {
return;
}
if (child->bs) {
assert(child->quiesced_parent);
bdrv_replace_child_tran(child, NULL, tran);
}
tran_add(tran, &bdrv_remove_child_drv, child);
}
/*
* Both @from and @to (if non-NULL) must be drained. @to must be kept drained
* until the transaction is completed.
*
* After calling this function, the transaction @tran may only be completed
* while holding a writer lock for the graph.
*/
static int GRAPH_WRLOCK
bdrv_replace_node_noperm(BlockDriverState *from,
BlockDriverState *to,
bool auto_skip, Transaction *tran,
Error **errp)
{
BdrvChild *c, *next;
GLOBAL_STATE_CODE();
assert(from->quiesce_counter);
assert(to->quiesce_counter);
QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) {
assert(c->bs == from);
if (!should_update_child(c, to)) {
if (auto_skip) {
continue;
}
error_setg(errp, "Should not change '%s' link to '%s'",
c->name, from->node_name);
return -EINVAL;
}
if (c->frozen) {
error_setg(errp, "Cannot change '%s' link to '%s'",
c->name, from->node_name);
return -EPERM;
}
bdrv_replace_child_tran(c, to, tran);
}
return 0;
}
/*
* Switch all parents of @from to point to @to instead. @from and @to must be in
* the same AioContext and both must be drained.
*
* With auto_skip=true bdrv_replace_node_common skips updating from parents
* if it creates a parent-child relation loop or if parent is block-job.
*
* With auto_skip=false the error is returned if from has a parent which should
* not be updated.
*
* With @detach_subchain=true @to must be in a backing chain of @from. In this
* case backing link of the cow-parent of @to is removed.
*/
static int GRAPH_WRLOCK
bdrv_replace_node_common(BlockDriverState *from, BlockDriverState *to,
bool auto_skip, bool detach_subchain, Error **errp)
{
Transaction *tran = tran_new();
g_autoptr(GSList) refresh_list = NULL;
BlockDriverState *to_cow_parent = NULL;
int ret;
GLOBAL_STATE_CODE();
assert(from->quiesce_counter);
assert(to->quiesce_counter);
assert(bdrv_get_aio_context(from) == bdrv_get_aio_context(to));
if (detach_subchain) {
assert(bdrv_chain_contains(from, to));
assert(from != to);
for (to_cow_parent = from;
bdrv_filter_or_cow_bs(to_cow_parent) != to;
to_cow_parent = bdrv_filter_or_cow_bs(to_cow_parent))
{
;
}
}
/*
* Do the replacement without permission update.
* Replacement may influence the permissions, we should calculate new
* permissions based on new graph. If we fail, we'll roll-back the
* replacement.
*/
ret = bdrv_replace_node_noperm(from, to, auto_skip, tran, errp);
if (ret < 0) {
goto out;
}
if (detach_subchain) {
/* to_cow_parent is already drained because from is drained */
bdrv_remove_child(bdrv_filter_or_cow_child(to_cow_parent), tran);
}
refresh_list = g_slist_prepend(refresh_list, to);
refresh_list = g_slist_prepend(refresh_list, from);
ret = bdrv_list_refresh_perms(refresh_list, NULL, tran, errp);
if (ret < 0) {
goto out;
}
ret = 0;
out:
tran_finalize(tran, ret);
return ret;
}
int bdrv_replace_node(BlockDriverState *from, BlockDriverState *to,
Error **errp)
{
return bdrv_replace_node_common(from, to, true, false, errp);
}
int bdrv_drop_filter(BlockDriverState *bs, Error **errp)
{
BlockDriverState *child_bs;
int ret;
GLOBAL_STATE_CODE();
bdrv_graph_rdlock_main_loop();
child_bs = bdrv_filter_or_cow_bs(bs);
bdrv_graph_rdunlock_main_loop();
bdrv_drained_begin(child_bs);
bdrv_graph_wrlock(bs);
ret = bdrv_replace_node_common(bs, child_bs, true, true, errp);
bdrv_graph_wrunlock();
bdrv_drained_end(child_bs);
return ret;
}
/*
* Add new bs contents at the top of an image chain while the chain is
* live, while keeping required fields on the top layer.
*
* This will modify the BlockDriverState fields, and swap contents
* between bs_new and bs_top. Both bs_new and bs_top are modified.
*
* bs_new must not be attached to a BlockBackend and must not have backing
* child.
*
* This function does not create any image files.
*
* The caller must hold the AioContext lock for @bs_top.
*/
int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
Error **errp)
{
int ret;
BdrvChild *child;
Transaction *tran = tran_new();
AioContext *old_context, *new_context = NULL;
GLOBAL_STATE_CODE();
bdrv_graph_rdlock_main_loop();
assert(!bs_new->backing);
bdrv_graph_rdunlock_main_loop();
old_context = bdrv_get_aio_context(bs_top);
bdrv_drained_begin(bs_top);
/*
* bdrv_drained_begin() requires that only the AioContext of the drained
* node is locked, and at this point it can still differ from the AioContext
* of bs_top.
*/
new_context = bdrv_get_aio_context(bs_new);
aio_context_release(old_context);
aio_context_acquire(new_context);
bdrv_drained_begin(bs_new);
aio_context_release(new_context);
aio_context_acquire(old_context);
new_context = NULL;
bdrv_graph_wrlock(bs_top);
child = bdrv_attach_child_noperm(bs_new, bs_top, "backing",
&child_of_bds, bdrv_backing_role(bs_new),
tran, errp);
if (!child) {
ret = -EINVAL;
goto out;
}
/*
* bdrv_attach_child_noperm could change the AioContext of bs_top and
* bs_new, but at least they are in the same AioContext now. This is the
* AioContext that we need to lock for the rest of the function.
*/
new_context = bdrv_get_aio_context(bs_top);
if (old_context != new_context) {
aio_context_release(old_context);
aio_context_acquire(new_context);
}
ret = bdrv_replace_node_noperm(bs_top, bs_new, true, tran, errp);
if (ret < 0) {
goto out;
}
ret = bdrv_refresh_perms(bs_new, tran, errp);
out:
tran_finalize(tran, ret);
bdrv_refresh_limits(bs_top, NULL, NULL);
bdrv_graph_wrunlock();
bdrv_drained_end(bs_top);
bdrv_drained_end(bs_new);
if (new_context && old_context != new_context) {
aio_context_release(new_context);
aio_context_acquire(old_context);
}
return ret;
}
/* Not for empty child */
int bdrv_replace_child_bs(BdrvChild *child, BlockDriverState *new_bs,
Error **errp)
{
int ret;
Transaction *tran = tran_new();
g_autoptr(GSList) refresh_list = NULL;
BlockDriverState *old_bs = child->bs;
GLOBAL_STATE_CODE();
bdrv_ref(old_bs);
bdrv_drained_begin(old_bs);
bdrv_drained_begin(new_bs);
bdrv_graph_wrlock(new_bs);
bdrv_replace_child_tran(child, new_bs, tran);
refresh_list = g_slist_prepend(refresh_list, old_bs);
refresh_list = g_slist_prepend(refresh_list, new_bs);
ret = bdrv_list_refresh_perms(refresh_list, NULL, tran, errp);
tran_finalize(tran, ret);
bdrv_graph_wrunlock();
bdrv_drained_end(old_bs);
bdrv_drained_end(new_bs);
bdrv_unref(old_bs);
return ret;
}
static void bdrv_delete(BlockDriverState *bs)
{
assert(bdrv_op_blocker_is_empty(bs));
assert(!bs->refcnt);
GLOBAL_STATE_CODE();
/* remove from list, if necessary */
if (bs->node_name[0] != '\0') {
QTAILQ_REMOVE(&graph_bdrv_states, bs, node_list);
}
QTAILQ_REMOVE(&all_bdrv_states, bs, bs_list);
bdrv_close(bs);
qemu_mutex_destroy(&bs->reqs_lock);
g_free(bs);
}
/*
* Replace @bs by newly created block node.
*
* @options is a QDict of options to pass to the block drivers, or NULL for an
* empty set of options. The reference to the QDict belongs to the block layer
* after the call (even on failure), so if the caller intends to reuse the
* dictionary, it needs to use qobject_ref() before calling bdrv_open.
*
* The caller holds the AioContext lock for @bs. It must make sure that @bs
* stays in the same AioContext, i.e. @options must not refer to nodes in a
* different AioContext.
*/
BlockDriverState *bdrv_insert_node(BlockDriverState *bs, QDict *options,
int flags, Error **errp)
{
ERRP_GUARD();
int ret;
AioContext *ctx = bdrv_get_aio_context(bs);
BlockDriverState *new_node_bs = NULL;
const char *drvname, *node_name;
BlockDriver *drv;
drvname = qdict_get_try_str(options, "driver");
if (!drvname) {
error_setg(errp, "driver is not specified");
goto fail;
}
drv = bdrv_find_format(drvname);
if (!drv) {
error_setg(errp, "Unknown driver: '%s'", drvname);
goto fail;
}
node_name = qdict_get_try_str(options, "node-name");
GLOBAL_STATE_CODE();
aio_context_release(ctx);
aio_context_acquire(qemu_get_aio_context());
new_node_bs = bdrv_new_open_driver_opts(drv, node_name, options, flags,
errp);
aio_context_release(qemu_get_aio_context());
aio_context_acquire(ctx);
assert(bdrv_get_aio_context(bs) == ctx);
options = NULL; /* bdrv_new_open_driver() eats options */
if (!new_node_bs) {
error_prepend(errp, "Could not create node: ");
goto fail;
}
/*
* Make sure that @bs doesn't go away until we have successfully attached
* all of its parents to @new_node_bs and undrained it again.
*/
bdrv_ref(bs);
bdrv_drained_begin(bs);
bdrv_drained_begin(new_node_bs);
bdrv_graph_wrlock(new_node_bs);
ret = bdrv_replace_node(bs, new_node_bs, errp);
bdrv_graph_wrunlock();
bdrv_drained_end(new_node_bs);
bdrv_drained_end(bs);
bdrv_unref(bs);
if (ret < 0) {
error_prepend(errp, "Could not replace node: ");
goto fail;
}
return new_node_bs;
fail:
qobject_unref(options);
bdrv_unref(new_node_bs);
return NULL;
}
/*
* Run consistency checks on an image
*
* Returns 0 if the check could be completed (it doesn't mean that the image is
* free of errors) or -errno when an internal error occurred. The results of the
* check are stored in res.
*/
int coroutine_fn bdrv_co_check(BlockDriverState *bs,
BdrvCheckResult *res, BdrvCheckMode fix)
{
IO_CODE();
assert_bdrv_graph_readable();
if (bs->drv == NULL) {
return -ENOMEDIUM;
}
if (bs->drv->bdrv_co_check == NULL) {
return -ENOTSUP;
}
memset(res, 0, sizeof(*res));
return bs->drv->bdrv_co_check(bs, res, fix);
}
/*
* Return values:
* 0 - success
* -EINVAL - backing format specified, but no file
* -ENOSPC - can't update the backing file because no space is left in the
* image file header
* -ENOTSUP - format driver doesn't support changing the backing file
*/
int coroutine_fn
bdrv_co_change_backing_file(BlockDriverState *bs, const char *backing_file,
const char *backing_fmt, bool require)
{
BlockDriver *drv = bs->drv;
int ret;
IO_CODE();
if (!drv) {
return -ENOMEDIUM;
}
/* Backing file format doesn't make sense without a backing file */
if (backing_fmt && !backing_file) {
return -EINVAL;
}
if (require && backing_file && !backing_fmt) {
return -EINVAL;
}
if (drv->bdrv_co_change_backing_file != NULL) {
ret = drv->bdrv_co_change_backing_file(bs, backing_file, backing_fmt);
} else {
ret = -ENOTSUP;
}
if (ret == 0) {
pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_file ?: "");
pstrcpy(bs->backing_format, sizeof(bs->backing_format), backing_fmt ?: "");
pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file),
backing_file ?: "");
}
return ret;
}
/*
* Finds the first non-filter node above bs in the chain between
* active and bs. The returned node is either an immediate parent of
* bs, or there are only filter nodes between the two.
*
* Returns NULL if bs is not found in active's image chain,
* or if active == bs.
*
* Returns the bottommost base image if bs == NULL.
*/
BlockDriverState *bdrv_find_overlay(BlockDriverState *active,
BlockDriverState *bs)
{
GLOBAL_STATE_CODE();
bs = bdrv_skip_filters(bs);
active = bdrv_skip_filters(active);
while (active) {
BlockDriverState *next = bdrv_backing_chain_next(active);
if (bs == next) {
return active;
}
active = next;
}
return NULL;
}
/* Given a BDS, searches for the base layer. */
BlockDriverState *bdrv_find_base(BlockDriverState *bs)
{
GLOBAL_STATE_CODE();
return bdrv_find_overlay(bs, NULL);
}
/*
* Return true if at least one of the COW (backing) and filter links
* between @bs and @base is frozen. @errp is set if that's the case.
* @base must be reachable from @bs, or NULL.
*/
static bool GRAPH_RDLOCK
bdrv_is_backing_chain_frozen(BlockDriverState *bs, BlockDriverState *base,
Error **errp)
{
BlockDriverState *i;
BdrvChild *child;
GLOBAL_STATE_CODE();
for (i = bs; i != base; i = child_bs(child)) {
child = bdrv_filter_or_cow_child(i);
if (child && child->frozen) {
error_setg(errp, "Cannot change '%s' link from '%s' to '%s'",
child->name, i->node_name, child->bs->node_name);
return true;
}
}
return false;
}
/*
* Freeze all COW (backing) and filter links between @bs and @base.
* If any of the links is already frozen the operation is aborted and
* none of the links are modified.
* @base must be reachable from @bs, or NULL.
* Returns 0 on success. On failure returns < 0 and sets @errp.
*/
int bdrv_freeze_backing_chain(BlockDriverState *bs, BlockDriverState *base,
Error **errp)
{
BlockDriverState *i;
BdrvChild *child;
GLOBAL_STATE_CODE();
if (bdrv_is_backing_chain_frozen(bs, base, errp)) {
return -EPERM;
}
for (i = bs; i != base; i = child_bs(child)) {
child = bdrv_filter_or_cow_child(i);
if (child && child->bs->never_freeze) {
error_setg(errp, "Cannot freeze '%s' link to '%s'",
child->name, child->bs->node_name);
return -EPERM;
}
}
for (i = bs; i != base; i = child_bs(child)) {
child = bdrv_filter_or_cow_child(i);
if (child) {
child->frozen = true;
}
}
return 0;
}
/*
* Unfreeze all COW (backing) and filter links between @bs and @base.
* The caller must ensure that all links are frozen before using this
* function.
* @base must be reachable from @bs, or NULL.
*/
void bdrv_unfreeze_backing_chain(BlockDriverState *bs, BlockDriverState *base)
{
BlockDriverState *i;
BdrvChild *child;
GLOBAL_STATE_CODE();
for (i = bs; i != base; i = child_bs(child)) {
child = bdrv_filter_or_cow_child(i);
if (child) {
assert(child->frozen);
child->frozen = false;
}
}
}
/*
* Drops images above 'base' up to and including 'top', and sets the image
* above 'top' to have base as its backing file.
*
* Requires that the overlay to 'top' is opened r/w, so that the backing file
* information in 'bs' can be properly updated.
*
* E.g., this will convert the following chain:
* bottom <- base <- intermediate <- top <- active
*
* to
*
* bottom <- base <- active
*
* It is allowed for bottom==base, in which case it converts:
*
* base <- intermediate <- top <- active
*
* to
*
* base <- active
*
* If backing_file_str is non-NULL, it will be used when modifying top's
* overlay image metadata.
*
* Error conditions:
* if active == top, that is considered an error
*
*/
int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base,
const char *backing_file_str)
{
BlockDriverState *explicit_top = top;
bool update_inherits_from;
BdrvChild *c;
Error *local_err = NULL;
int ret = -EIO;
g_autoptr(GSList) updated_children = NULL;
GSList *p;
GLOBAL_STATE_CODE();
bdrv_ref(top);
bdrv_drained_begin(base);
bdrv_graph_wrlock(base);
if (!top->drv || !base->drv) {
goto exit_wrlock;
}
/* Make sure that base is in the backing chain of top */
if (!bdrv_chain_contains(top, base)) {
goto exit_wrlock;
}
/* If 'base' recursively inherits from 'top' then we should set
* base->inherits_from to top->inherits_from after 'top' and all
* other intermediate nodes have been dropped.
* If 'top' is an implicit node (e.g. "commit_top") we should skip
* it because no one inherits from it. We use explicit_top for that. */
explicit_top = bdrv_skip_implicit_filters(explicit_top);
update_inherits_from = bdrv_inherits_from_recursive(base, explicit_top);
/* success - we can delete the intermediate states, and link top->base */
if (!backing_file_str) {
bdrv_refresh_filename(base);
backing_file_str = base->filename;
}
QLIST_FOREACH(c, &top->parents, next_parent) {
updated_children = g_slist_prepend(updated_children, c);
}
/*
* It seems correct to pass detach_subchain=true here, but it triggers
* one more yet not fixed bug, when due to nested aio_poll loop we switch to
* another drained section, which modify the graph (for example, removing
* the child, which we keep in updated_children list). So, it's a TODO.
*
* Note, bug triggered if pass detach_subchain=true here and run
* test-bdrv-drain. test_drop_intermediate_poll() test-case will crash.
* That's a FIXME.
*/
bdrv_replace_node_common(top, base, false, false, &local_err);
bdrv_graph_wrunlock();
if (local_err) {
error_report_err(local_err);
goto exit;
}
for (p = updated_children; p; p = p->next) {
c = p->data;
if (c->klass->update_filename) {
ret = c->klass->update_filename(c, base, backing_file_str,
&local_err);
if (ret < 0) {
/*
* TODO: Actually, we want to rollback all previous iterations
* of this loop, and (which is almost impossible) previous
* bdrv_replace_node()...
*
* Note, that c->klass->update_filename may lead to permission
* update, so it's a bad idea to call it inside permission
* update transaction of bdrv_replace_node.
*/
error_report_err(local_err);
goto exit;
}
}
}
if (update_inherits_from) {
base->inherits_from = explicit_top->inherits_from;
}
ret = 0;
goto exit;
exit_wrlock:
bdrv_graph_wrunlock();
exit:
bdrv_drained_end(base);
bdrv_unref(top);
return ret;
}
/**
* Implementation of BlockDriver.bdrv_co_get_allocated_file_size() that
* sums the size of all data-bearing children. (This excludes backing
* children.)
*/
static int64_t coroutine_fn GRAPH_RDLOCK
bdrv_sum_allocated_file_size(BlockDriverState *bs)
{
BdrvChild *child;
int64_t child_size, sum = 0;
QLIST_FOREACH(child, &bs->children, next) {
if (child->role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA |
BDRV_CHILD_FILTERED))
{
child_size = bdrv_co_get_allocated_file_size(child->bs);
if (child_size < 0) {
return child_size;
}
sum += child_size;
}
}
return sum;
}
/**
* Length of a allocated file in bytes. Sparse files are counted by actual
* allocated space. Return < 0 if error or unknown.
*/
int64_t coroutine_fn bdrv_co_get_allocated_file_size(BlockDriverState *bs)
{
BlockDriver *drv = bs->drv;
IO_CODE();
assert_bdrv_graph_readable();
if (!drv) {
return -ENOMEDIUM;
}
if (drv->bdrv_co_get_allocated_file_size) {
return drv->bdrv_co_get_allocated_file_size(bs);
}
if (drv->bdrv_file_open) {
/*
* Protocol drivers default to -ENOTSUP (most of their data is
* not stored in any of their children (if they even have any),
* so there is no generic way to figure it out).
*/
return -ENOTSUP;
} else if (drv->is_filter) {
/* Filter drivers default to the size of their filtered child */
return bdrv_co_get_allocated_file_size(bdrv_filter_bs(bs));
} else {
/* Other drivers default to summing their children's sizes */
return bdrv_sum_allocated_file_size(bs);
}
}
/*
* bdrv_measure:
* @drv: Format driver
* @opts: Creation options for new image
* @in_bs: Existing image containing data for new image (may be NULL)
* @errp: Error object
* Returns: A #BlockMeasureInfo (free using qapi_free_BlockMeasureInfo())
* or NULL on error
*
* Calculate file size required to create a new image.
*
* If @in_bs is given then space for allocated clusters and zero clusters
* from that image are included in the calculation. If @opts contains a
* backing file that is shared by @in_bs then backing clusters may be omitted
* from the calculation.
*
* If @in_bs is NULL then the calculation includes no allocated clusters
* unless a preallocation option is given in @opts.
*
* Note that @in_bs may use a different BlockDriver from @drv.
*
* If an error occurs the @errp pointer is set.
*/
BlockMeasureInfo *bdrv_measure(BlockDriver *drv, QemuOpts *opts,
BlockDriverState *in_bs, Error **errp)
{
IO_CODE();
if (!drv->bdrv_measure) {
error_setg(errp, "Block driver '%s' does not support size measurement",
drv->format_name);
return NULL;
}
return drv->bdrv_measure(opts, in_bs, errp);
}
/**
* Return number of sectors on success, -errno on error.
*/
int64_t coroutine_fn bdrv_co_nb_sectors(BlockDriverState *bs)
{
BlockDriver *drv = bs->drv;
IO_CODE();
assert_bdrv_graph_readable();
if (!drv)
return -ENOMEDIUM;
if (bs->bl.has_variable_length) {
int ret = bdrv_co_refresh_total_sectors(bs, bs->total_sectors);
if (ret < 0) {
return ret;
}
}
return bs->total_sectors;
}
/*
* This wrapper is written by hand because this function is in the hot I/O path,
* via blk_get_geometry.
*/
int64_t coroutine_mixed_fn bdrv_nb_sectors(BlockDriverState *bs)
{
BlockDriver *drv = bs->drv;
IO_CODE();
if (!drv)
return -ENOMEDIUM;
if (bs->bl.has_variable_length) {
int ret = bdrv_refresh_total_sectors(bs, bs->total_sectors);
if (ret < 0) {
return ret;
}
}
return bs->total_sectors;
}
/**
* Return length in bytes on success, -errno on error.
* The length is always a multiple of BDRV_SECTOR_SIZE.
*/
int64_t coroutine_fn bdrv_co_getlength(BlockDriverState *bs)
{
int64_t ret;
IO_CODE();
assert_bdrv_graph_readable();
ret = bdrv_co_nb_sectors(bs);
if (ret < 0) {
return ret;
}
if (ret > INT64_MAX / BDRV_SECTOR_SIZE) {
return -EFBIG;
}
return ret * BDRV_SECTOR_SIZE;
}
bool bdrv_is_sg(BlockDriverState *bs)
{
IO_CODE();
return bs->sg;
}
/**
* Return whether the given node supports compressed writes.
*/
bool bdrv_supports_compressed_writes(BlockDriverState *bs)
{
BlockDriverState *filtered;
IO_CODE();
if (!bs->drv || !block_driver_can_compress(bs->drv)) {
return false;
}
filtered = bdrv_filter_bs(bs);
if (filtered) {
/*
* Filters can only forward compressed writes, so we have to
* check the child.
*/
return bdrv_supports_compressed_writes(filtered);
}
return true;
}
const char *bdrv_get_format_name(BlockDriverState *bs)
{
IO_CODE();
return bs->drv ? bs->drv->format_name : NULL;
}
static int qsort_strcmp(const void *a, const void *b)
{
return strcmp(*(char *const *)a, *(char *const *)b);
}
void bdrv_iterate_format(void (*it)(void *opaque, const char *name),
void *opaque, bool read_only)
{
BlockDriver *drv;
int count = 0;
int i;
const char **formats = NULL;
GLOBAL_STATE_CODE();
QLIST_FOREACH(drv, &bdrv_drivers, list) {
if (drv->format_name) {
bool found = false;
if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, read_only)) {
continue;
}
i = count;
while (formats && i && !found) {
found = !strcmp(formats[--i], drv->format_name);
}
if (!found) {
formats = g_renew(const char *, formats, count + 1);
formats[count++] = drv->format_name;
}
}
}
for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); i++) {
const char *format_name = block_driver_modules[i].format_name;
if (format_name) {
bool found = false;
int j = count;
if (use_bdrv_whitelist &&
!bdrv_format_is_whitelisted(format_name, read_only)) {
continue;
}
while (formats && j && !found) {
found = !strcmp(formats[--j], format_name);
}
if (!found) {
formats = g_renew(const char *, formats, count + 1);
formats[count++] = format_name;
}
}
}
qsort(formats, count, sizeof(formats[0]), qsort_strcmp);
for (i = 0; i < count; i++) {
it(opaque, formats[i]);
}
g_free(formats);
}
/* This function is to find a node in the bs graph */
BlockDriverState *bdrv_find_node(const char *node_name)
{
BlockDriverState *bs;
assert(node_name);
GLOBAL_STATE_CODE();
QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
if (!strcmp(node_name, bs->node_name)) {
return bs;
}
}
return NULL;
}
/* Put this QMP function here so it can access the static graph_bdrv_states. */
BlockDeviceInfoList *bdrv_named_nodes_list(bool flat,
Error **errp)
{
BlockDeviceInfoList *list;
BlockDriverState *bs;
GLOBAL_STATE_CODE();
GRAPH_RDLOCK_GUARD_MAINLOOP();
list = NULL;
QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
BlockDeviceInfo *info = bdrv_block_device_info(NULL, bs, flat, errp);
if (!info) {
qapi_free_BlockDeviceInfoList(list);
return NULL;
}
QAPI_LIST_PREPEND(list, info);
}
return list;
}
typedef struct XDbgBlockGraphConstructor {
XDbgBlockGraph *graph;
GHashTable *graph_nodes;
} XDbgBlockGraphConstructor;
static XDbgBlockGraphConstructor *xdbg_graph_new(void)
{
XDbgBlockGraphConstructor *gr = g_new(XDbgBlockGraphConstructor, 1);
gr->graph = g_new0(XDbgBlockGraph, 1);
gr->graph_nodes = g_hash_table_new(NULL, NULL);
return gr;
}
static XDbgBlockGraph *xdbg_graph_finalize(XDbgBlockGraphConstructor *gr)
{
XDbgBlockGraph *graph = gr->graph;
g_hash_table_destroy(gr->graph_nodes);
g_free(gr);
return graph;
}
static uintptr_t xdbg_graph_node_num(XDbgBlockGraphConstructor *gr, void *node)
{
uintptr_t ret = (uintptr_t)g_hash_table_lookup(gr->graph_nodes, node);
if (ret != 0) {
return ret;
}
/*
* Start counting from 1, not 0, because 0 interferes with not-found (NULL)
* answer of g_hash_table_lookup.
*/
ret = g_hash_table_size(gr->graph_nodes) + 1;
g_hash_table_insert(gr->graph_nodes, node, (void *)ret);
return ret;
}
static void xdbg_graph_add_node(XDbgBlockGraphConstructor *gr, void *node,
XDbgBlockGraphNodeType type, const char *name)
{
XDbgBlockGraphNode *n;
n = g_new0(XDbgBlockGraphNode, 1);
n->id = xdbg_graph_node_num(gr, node);
n->type = type;
n->name = g_strdup(name);
QAPI_LIST_PREPEND(gr->graph->nodes, n);
}
static void xdbg_graph_add_edge(XDbgBlockGraphConstructor *gr, void *parent,
const BdrvChild *child)
{
BlockPermission qapi_perm;
XDbgBlockGraphEdge *edge;
GLOBAL_STATE_CODE();
edge = g_new0(XDbgBlockGraphEdge, 1);
edge->parent = xdbg_graph_node_num(gr, parent);
edge->child = xdbg_graph_node_num(gr, child->bs);
edge->name = g_strdup(child->name);
for (qapi_perm = 0; qapi_perm < BLOCK_PERMISSION__MAX; qapi_perm++) {
uint64_t flag = bdrv_qapi_perm_to_blk_perm(qapi_perm);
if (flag & child->perm) {
QAPI_LIST_PREPEND(edge->perm, qapi_perm);
}
if (flag & child->shared_perm) {
QAPI_LIST_PREPEND(edge->shared_perm, qapi_perm);
}
}
QAPI_LIST_PREPEND(gr->graph->edges, edge);
}
XDbgBlockGraph *bdrv_get_xdbg_block_graph(Error **errp)
{
BlockBackend *blk;
BlockJob *job;
BlockDriverState *bs;
BdrvChild *child;
XDbgBlockGraphConstructor *gr = xdbg_graph_new();
GLOBAL_STATE_CODE();
for (blk = blk_all_next(NULL); blk; blk = blk_all_next(blk)) {
char *allocated_name = NULL;
const char *name = blk_name(blk);
if (!*name) {
name = allocated_name = blk_get_attached_dev_id(blk);
}
xdbg_graph_add_node(gr, blk, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_BACKEND,
name);
g_free(allocated_name);
if (blk_root(blk)) {
xdbg_graph_add_edge(gr, blk, blk_root(blk));
}
}
WITH_JOB_LOCK_GUARD() {
for (job = block_job_next_locked(NULL); job;
job = block_job_next_locked(job)) {
GSList *el;
xdbg_graph_add_node(gr, job, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_JOB,
job->job.id);
for (el = job->nodes; el; el = el->next) {
xdbg_graph_add_edge(gr, job, (BdrvChild *)el->data);
}
}
}
QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
xdbg_graph_add_node(gr, bs, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_DRIVER,
bs->node_name);
QLIST_FOREACH(child, &bs->children, next) {
xdbg_graph_add_edge(gr, bs, child);
}
}
return xdbg_graph_finalize(gr);
}
BlockDriverState *bdrv_lookup_bs(const char *device,
const char *node_name,
Error **errp)
{
BlockBackend *blk;
BlockDriverState *bs;
GLOBAL_STATE_CODE();
if (device) {
blk = blk_by_name(device);
if (blk) {
bs = blk_bs(blk);
if (!bs) {
error_setg(errp, "Device '%s' has no medium", device);
}
return bs;
}
}
if (node_name) {
bs = bdrv_find_node(node_name);
if (bs) {
return bs;
}
}
error_setg(errp, "Cannot find device=\'%s\' nor node-name=\'%s\'",
device ? device : "",
node_name ? node_name : "");
return NULL;
}
/* If 'base' is in the same chain as 'top', return true. Otherwise,
* return false. If either argument is NULL, return false. */
bool bdrv_chain_contains(BlockDriverState *top, BlockDriverState *base)
{
GLOBAL_STATE_CODE();
while (top && top != base) {
top = bdrv_filter_or_cow_bs(top);
}
return top != NULL;
}
BlockDriverState *bdrv_next_node(BlockDriverState *bs)
{
GLOBAL_STATE_CODE();
if (!bs) {
return QTAILQ_FIRST(&graph_bdrv_states);
}
return QTAILQ_NEXT(bs, node_list);
}
BlockDriverState *bdrv_next_all_states(BlockDriverState *bs)
{
GLOBAL_STATE_CODE();
if (!bs) {
return QTAILQ_FIRST(&all_bdrv_states);
}
return QTAILQ_NEXT(bs, bs_list);
}
const char *bdrv_get_node_name(const BlockDriverState *bs)
{
IO_CODE();
return bs->node_name;
}
const char *bdrv_get_parent_name(const BlockDriverState *bs)
{
BdrvChild *c;
const char *name;
IO_CODE();
/* If multiple parents have a name, just pick the first one. */
QLIST_FOREACH(c, &bs->parents, next_parent) {
if (c->klass->get_name) {
name = c->klass->get_name(c);
if (name && *name) {
return name;
}
}
}
return NULL;
}
/* TODO check what callers really want: bs->node_name or blk_name() */
const char *bdrv_get_device_name(const BlockDriverState *bs)
{
IO_CODE();
return bdrv_get_parent_name(bs) ?: "";
}
/* This can be used to identify nodes that might not have a device
* name associated. Since node and device names live in the same
* namespace, the result is unambiguous. The exception is if both are
* absent, then this returns an empty (non-null) string. */
const char *bdrv_get_device_or_node_name(const BlockDriverState *bs)
{
IO_CODE();
return bdrv_get_parent_name(bs) ?: bs->node_name;
}
int bdrv_get_flags(BlockDriverState *bs)
{
IO_CODE();
return bs->open_flags;
}
int bdrv_has_zero_init_1(BlockDriverState *bs)
{
GLOBAL_STATE_CODE();
return 1;
}
int coroutine_mixed_fn bdrv_has_zero_init(BlockDriverState *bs)
{
BlockDriverState *filtered;
GLOBAL_STATE_CODE();
if (!bs->drv) {
return 0;
}
/* If BS is a copy on write image, it is initialized to
the contents of the base image, which may not be zeroes. */
if (bdrv_cow_child(bs)) {
return 0;
}
if (bs->drv->bdrv_has_zero_init) {
return bs->drv->bdrv_has_zero_init(bs);
}
filtered = bdrv_filter_bs(bs);
if (filtered) {
return bdrv_has_zero_init(filtered);
}
/* safe default */
return 0;
}
bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs)
{
IO_CODE();
if (!(bs->open_flags & BDRV_O_UNMAP)) {
return false;
}
return bs->supported_zero_flags & BDRV_REQ_MAY_UNMAP;
}
void bdrv_get_backing_filename(BlockDriverState *bs,
char *filename, int filename_size)
{
IO_CODE();
pstrcpy(filename, filename_size, bs->backing_file);
}
int coroutine_fn bdrv_co_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
{
int ret;
BlockDriver *drv = bs->drv;
IO_CODE();
assert_bdrv_graph_readable();
/* if bs->drv == NULL, bs is closed, so there's nothing to do here */
if (!drv) {
return -ENOMEDIUM;
}
if (!drv->bdrv_co_get_info) {
BlockDriverState *filtered = bdrv_filter_bs(bs);
if (filtered) {
return bdrv_co_get_info(filtered, bdi);
}
return -ENOTSUP;
}
memset(bdi, 0, sizeof(*bdi));
ret = drv->bdrv_co_get_info(bs, bdi);
if (bdi->subcluster_size == 0) {
/*
* If the driver left this unset, subclusters are not supported.
* Then it is safe to treat each cluster as having only one subcluster.
*/
bdi->subcluster_size = bdi->cluster_size;
}
if (ret < 0) {
return ret;
}
if (bdi->cluster_size > BDRV_MAX_ALIGNMENT) {
return -EINVAL;
}
return 0;
}
ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs,
Error **errp)
{
BlockDriver *drv = bs->drv;
IO_CODE();
if (drv && drv->bdrv_get_specific_info) {
return drv->bdrv_get_specific_info(bs, errp);
}
return NULL;
}
BlockStatsSpecific *bdrv_get_specific_stats(BlockDriverState *bs)
{
BlockDriver *drv = bs->drv;
IO_CODE();
if (!drv || !drv->bdrv_get_specific_stats) {
return NULL;
}
return drv->bdrv_get_specific_stats(bs);
}
void coroutine_fn bdrv_co_debug_event(BlockDriverState *bs, BlkdebugEvent event)
{
IO_CODE();
assert_bdrv_graph_readable();
if (!bs || !bs->drv || !bs->drv->bdrv_co_debug_event) {
return;
}
bs->drv->bdrv_co_debug_event(bs, event);
}
static BlockDriverState * GRAPH_RDLOCK
bdrv_find_debug_node(BlockDriverState *bs)
{
GLOBAL_STATE_CODE();
while (bs && bs->drv && !bs->drv->bdrv_debug_breakpoint) {
bs = bdrv_primary_bs(bs);
}
if (bs && bs->drv && bs->drv->bdrv_debug_breakpoint) {
assert(bs->drv->bdrv_debug_remove_breakpoint);
return bs;
}
return NULL;
}
int bdrv_debug_breakpoint(BlockDriverState *bs, const char *event,
const char *tag)
{
GLOBAL_STATE_CODE();
GRAPH_RDLOCK_GUARD_MAINLOOP();
bs = bdrv_find_debug_node(bs);
if (bs) {
return bs->drv->bdrv_debug_breakpoint(bs, event, tag);
}
return -ENOTSUP;
}
int bdrv_debug_remove_breakpoint(BlockDriverState *bs, const char *tag)
{
GLOBAL_STATE_CODE();
GRAPH_RDLOCK_GUARD_MAINLOOP();
bs = bdrv_find_debug_node(bs);
if (bs) {
return bs->drv->bdrv_debug_remove_breakpoint(bs, tag);
}
return -ENOTSUP;
}
int bdrv_debug_resume(BlockDriverState *bs, const char *tag)
{
GLOBAL_STATE_CODE();
GRAPH_RDLOCK_GUARD_MAINLOOP();
while (bs && (!bs->drv || !bs->drv->bdrv_debug_resume)) {
bs = bdrv_primary_bs(bs);
}
if (bs && bs->drv && bs->drv->bdrv_debug_resume) {
return bs->drv->bdrv_debug_resume(bs, tag);
}
return -ENOTSUP;
}
bool bdrv_debug_is_suspended(BlockDriverState *bs, const char *tag)
{
GLOBAL_STATE_CODE();
GRAPH_RDLOCK_GUARD_MAINLOOP();
while (bs && bs->drv && !bs->drv->bdrv_debug_is_suspended) {
bs = bdrv_primary_bs(bs);
}
if (bs && bs->drv && bs->drv->bdrv_debug_is_suspended) {
return bs->drv->bdrv_debug_is_suspended(bs, tag);
}
return false;
}
/* backing_file can either be relative, or absolute, or a protocol. If it is
* relative, it must be relative to the chain. So, passing in bs->filename
* from a BDS as backing_file should not be done, as that may be relative to
* the CWD rather than the chain. */
BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
const char *backing_file)
{
char *filename_full = NULL;
char *backing_file_full = NULL;
char *filename_tmp = NULL;
int is_protocol = 0;
bool filenames_refreshed = false;
BlockDriverState *curr_bs = NULL;
BlockDriverState *retval = NULL;
BlockDriverState *bs_below;
GLOBAL_STATE_CODE();
GRAPH_RDLOCK_GUARD_MAINLOOP();
if (!bs || !bs->drv || !backing_file) {
return NULL;
}
filename_full = g_malloc(PATH_MAX);
backing_file_full = g_malloc(PATH_MAX);
is_protocol = path_has_protocol(backing_file);
/*
* Being largely a legacy function, skip any filters here
* (because filters do not have normal filenames, so they cannot
* match anyway; and allowing json:{} filenames is a bit out of
* scope).
*/
for (curr_bs = bdrv_skip_filters(bs);
bdrv_cow_child(curr_bs) != NULL;
curr_bs = bs_below)
{
bs_below = bdrv_backing_chain_next(curr_bs);
if (bdrv_backing_overridden(curr_bs)) {
/*
* If the backing file was overridden, we can only compare
* directly against the backing node's filename.
*/
if (!filenames_refreshed) {
/*
* This will automatically refresh all of the
* filenames in the rest of the backing chain, so we
* only need to do this once.
*/
bdrv_refresh_filename(bs_below);
filenames_refreshed = true;
}
if (strcmp(backing_file, bs_below->filename) == 0) {
retval = bs_below;
break;
}
} else if (is_protocol || path_has_protocol(curr_bs->backing_file)) {
/*
* If either of the filename paths is actually a protocol, then
* compare unmodified paths; otherwise make paths relative.
*/
char *backing_file_full_ret;
if (strcmp(backing_file, curr_bs->backing_file) == 0) {
retval = bs_below;
break;
}
/* Also check against the full backing filename for the image */
backing_file_full_ret = bdrv_get_full_backing_filename(curr_bs,
NULL);
if (backing_file_full_ret) {
bool equal = strcmp(backing_file, backing_file_full_ret) == 0;
g_free(backing_file_full_ret);
if (equal) {
retval = bs_below;
break;
}
}
} else {
/* If not an absolute filename path, make it relative to the current
* image's filename path */
filename_tmp = bdrv_make_absolute_filename(curr_bs, backing_file,
NULL);
/* We are going to compare canonicalized absolute pathnames */
if (!filename_tmp || !realpath(filename_tmp, filename_full)) {
g_free(filename_tmp);
continue;
}
g_free(filename_tmp);
/* We need to make sure the backing filename we are comparing against
* is relative to the current image filename (or absolute) */
filename_tmp = bdrv_get_full_backing_filename(curr_bs, NULL);
if (!filename_tmp || !realpath(filename_tmp, backing_file_full)) {
g_free(filename_tmp);
continue;
}
g_free(filename_tmp);
if (strcmp(backing_file_full, filename_full) == 0) {
retval = bs_below;
break;
}
}
}
g_free(filename_full);
g_free(backing_file_full);
return retval;
}
void bdrv_init(void)
{
#ifdef CONFIG_BDRV_WHITELIST_TOOLS
use_bdrv_whitelist = 1;
#endif
module_call_init(MODULE_INIT_BLOCK);
}
void bdrv_init_with_whitelist(void)
{
use_bdrv_whitelist = 1;
bdrv_init();
}
int bdrv_activate(BlockDriverState *bs, Error **errp)
{
BdrvChild *child, *parent;
Error *local_err = NULL;
int ret;
BdrvDirtyBitmap *bm;
GLOBAL_STATE_CODE();
GRAPH_RDLOCK_GUARD_MAINLOOP();
if (!bs->drv) {
return -ENOMEDIUM;
}
QLIST_FOREACH(child, &bs->children, next) {
bdrv_activate(child->bs, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return -EINVAL;
}
}
/*
* Update permissions, they may differ for inactive nodes.
*
* Note that the required permissions of inactive images are always a
* subset of the permissions required after activating the image. This
* allows us to just get the permissions upfront without restricting
* bdrv_co_invalidate_cache().
*
* It also means that in error cases, we don't have to try and revert to
* the old permissions (which is an operation that could fail, too). We can
* just keep the extended permissions for the next time that an activation
* of the image is tried.
*/
if (bs->open_flags & BDRV_O_INACTIVE) {
bs->open_flags &= ~BDRV_O_INACTIVE;
ret = bdrv_refresh_perms(bs, NULL, errp);
if (ret < 0) {
bs->open_flags |= BDRV_O_INACTIVE;
return ret;
}
ret = bdrv_invalidate_cache(bs, errp);
if (ret < 0) {
bs->open_flags |= BDRV_O_INACTIVE;
return ret;
}
FOR_EACH_DIRTY_BITMAP(bs, bm) {
bdrv_dirty_bitmap_skip_store(bm, false);
}
ret = bdrv_refresh_total_sectors(bs, bs->total_sectors);
if (ret < 0) {
bs->open_flags |= BDRV_O_INACTIVE;
error_setg_errno(errp, -ret, "Could not refresh total sector count");
return ret;
}
}
QLIST_FOREACH(parent, &bs->parents, next_parent) {
if (parent->klass->activate) {
parent->klass->activate(parent, &local_err);
if (local_err) {
bs->open_flags |= BDRV_O_INACTIVE;
error_propagate(errp, local_err);
return -EINVAL;
}
}
}
return 0;
}
int coroutine_fn bdrv_co_invalidate_cache(BlockDriverState *bs, Error **errp)
{
Error *local_err = NULL;
IO_CODE();
assert(!(bs->open_flags & BDRV_O_INACTIVE));
assert_bdrv_graph_readable();
if (bs->drv->bdrv_co_invalidate_cache) {
bs->drv->bdrv_co_invalidate_cache(bs, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return -EINVAL;
}
}
return 0;
}
void bdrv_activate_all(Error **errp)
{
BlockDriverState *bs;
BdrvNextIterator it;
GLOBAL_STATE_CODE();
GRAPH_RDLOCK_GUARD_MAINLOOP();
for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
AioContext *aio_context = bdrv_get_aio_context(bs);
int ret;
aio_context_acquire(aio_context);
ret = bdrv_activate(bs, errp);
aio_context_release(aio_context);
if (ret < 0) {
bdrv_next_cleanup(&it);
return;
}
}
}
static bool GRAPH_RDLOCK
bdrv_has_bds_parent(BlockDriverState *bs, bool only_active)
{
BdrvChild *parent;
GLOBAL_STATE_CODE();
QLIST_FOREACH(parent, &bs->parents, next_parent) {
if (parent->klass->parent_is_bds) {
BlockDriverState *parent_bs = parent->opaque;
if (!only_active || !(parent_bs->open_flags & BDRV_O_INACTIVE)) {
return true;
}
}
}
return false;
}
static int GRAPH_RDLOCK bdrv_inactivate_recurse(BlockDriverState *bs)
{
BdrvChild *child, *parent;
int ret;
uint64_t cumulative_perms, cumulative_shared_perms;
GLOBAL_STATE_CODE();
if (!bs->drv) {
return -ENOMEDIUM;
}
/* Make sure that we don't inactivate a child before its parent.
* It will be covered by recursion from the yet active parent. */
if (bdrv_has_bds_parent(bs, true)) {
return 0;
}
assert(!(bs->open_flags & BDRV_O_INACTIVE));
/* Inactivate this node */
if (bs->drv->bdrv_inactivate) {
ret = bs->drv->bdrv_inactivate(bs);
if (ret < 0) {
return ret;
}
}
QLIST_FOREACH(parent, &bs->parents, next_parent) {
if (parent->klass->inactivate) {
ret = parent->klass->inactivate(parent);
if (ret < 0) {
return ret;
}
}
}
bdrv_get_cumulative_perm(bs, &cumulative_perms,
&cumulative_shared_perms);
if (cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) {
/* Our inactive parents still need write access. Inactivation failed. */
return -EPERM;
}
bs->open_flags |= BDRV_O_INACTIVE;
/*
* Update permissions, they may differ for inactive nodes.
* We only tried to loosen restrictions, so errors are not fatal, ignore
* them.
*/
bdrv_refresh_perms(bs, NULL, NULL);
/* Recursively inactivate children */
QLIST_FOREACH(child, &bs->children, next) {
ret = bdrv_inactivate_recurse(child->bs);
if (ret < 0) {
return ret;
}
}
return 0;
}
int bdrv_inactivate_all(void)
{
BlockDriverState *bs = NULL;
BdrvNextIterator it;
int ret = 0;
GSList *aio_ctxs = NULL, *ctx;
GLOBAL_STATE_CODE();
GRAPH_RDLOCK_GUARD_MAINLOOP();
for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
AioContext *aio_context = bdrv_get_aio_context(bs);
if (!g_slist_find(aio_ctxs, aio_context)) {
aio_ctxs = g_slist_prepend(aio_ctxs, aio_context);
aio_context_acquire(aio_context);
}
}
for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
/* Nodes with BDS parents are covered by recursion from the last
* parent that gets inactivated. Don't inactivate them a second
* time if that has already happened. */
if (bdrv_has_bds_parent(bs, false)) {
continue;
}
ret = bdrv_inactivate_recurse(bs);
if (ret < 0) {
bdrv_next_cleanup(&it);
goto out;
}
}
out:
for (ctx = aio_ctxs; ctx != NULL; ctx = ctx->next) {
AioContext *aio_context = ctx->data;
aio_context_release(aio_context);
}
g_slist_free(aio_ctxs);
return ret;
}
/**************************************************************/
/* removable device support */
/**
* Return TRUE if the media is present
*/
bool coroutine_fn bdrv_co_is_inserted(BlockDriverState *bs)
{
BlockDriver *drv = bs->drv;
BdrvChild *child;
IO_CODE();
assert_bdrv_graph_readable();
if (!drv) {
return false;
}
if (drv->bdrv_co_is_inserted) {
return drv->bdrv_co_is_inserted(bs);
}
QLIST_FOREACH(child, &bs->children, next) {
if (!bdrv_co_is_inserted(child->bs)) {
return false;
}
}
return true;
}
/**
* If eject_flag is TRUE, eject the media. Otherwise, close the tray
*/
void coroutine_fn bdrv_co_eject(BlockDriverState *bs, bool eject_flag)
{
BlockDriver *drv = bs->drv;
IO_CODE();
assert_bdrv_graph_readable();
if (drv && drv->bdrv_co_eject) {
drv->bdrv_co_eject(bs, eject_flag);
}
}
/**
* Lock or unlock the media (if it is locked, the user won't be able
* to eject it manually).
*/
void coroutine_fn bdrv_co_lock_medium(BlockDriverState *bs, bool locked)
{
BlockDriver *drv = bs->drv;
IO_CODE();
assert_bdrv_graph_readable();
trace_bdrv_lock_medium(bs, locked);
if (drv && drv->bdrv_co_lock_medium) {
drv->bdrv_co_lock_medium(bs, locked);
}
}
/* Get a reference to bs */
void bdrv_ref(BlockDriverState *bs)
{
GLOBAL_STATE_CODE();
bs->refcnt++;
}
/* Release a previously grabbed reference to bs.
* If after releasing, reference count is zero, the BlockDriverState is
* deleted. */
void bdrv_unref(BlockDriverState *bs)
{
GLOBAL_STATE_CODE();
if (!bs) {
return;
}
assert(bs->refcnt > 0);
if (--bs->refcnt == 0) {
bdrv_delete(bs);
}
}
/*
* Release a BlockDriverState reference while holding the graph write lock.
*
* Calling bdrv_unref() directly is forbidden while holding the graph lock
* because bdrv_close() both involves polling and taking the graph lock
* internally. bdrv_schedule_unref() instead delays decreasing the refcount and
* possibly closing @bs until the graph lock is released.
*/
void bdrv_schedule_unref(BlockDriverState *bs)
{
if (!bs) {
return;
}
aio_bh_schedule_oneshot(qemu_get_aio_context(),
(QEMUBHFunc *) bdrv_unref, bs);
}
struct BdrvOpBlocker {
Error *reason;
QLIST_ENTRY(BdrvOpBlocker) list;
};
bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp)
{
BdrvOpBlocker *blocker;
GLOBAL_STATE_CODE();
assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
if (!QLIST_EMPTY(&bs->op_blockers[op])) {
blocker = QLIST_FIRST(&bs->op_blockers[op]);
error_propagate_prepend(errp, error_copy(blocker->reason),
"Node '%s' is busy: ",
bdrv_get_device_or_node_name(bs));
return true;
}
return false;
}
void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason)
{
BdrvOpBlocker *blocker;
GLOBAL_STATE_CODE();
assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
blocker = g_new0(BdrvOpBlocker, 1);
blocker->reason = reason;
QLIST_INSERT_HEAD(&bs->op_blockers[op], blocker, list);
}
void bdrv_op_unblock(BlockDriverState *bs, BlockOpType op, Error *reason)
{
BdrvOpBlocker *blocker, *next;
GLOBAL_STATE_CODE();
assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
QLIST_FOREACH_SAFE(blocker, &bs->op_blockers[op], list, next) {
if (blocker->reason == reason) {
QLIST_REMOVE(blocker, list);
g_free(blocker);
}
}
}
void bdrv_op_block_all(BlockDriverState *bs, Error *reason)
{
int i;
GLOBAL_STATE_CODE();
for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
bdrv_op_block(bs, i, reason);
}
}
void bdrv_op_unblock_all(BlockDriverState *bs, Error *reason)
{
int i;
GLOBAL_STATE_CODE();
for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
bdrv_op_unblock(bs, i, reason);
}
}
bool bdrv_op_blocker_is_empty(BlockDriverState *bs)
{
int i;
GLOBAL_STATE_CODE();
for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
if (!QLIST_EMPTY(&bs->op_blockers[i])) {
return false;
}
}
return true;
}
/*
* Must not be called while holding the lock of an AioContext other than the
* current one.
*/
void bdrv_img_create(const char *filename, const char *fmt,
const char *base_filename, const char *base_fmt,
char *options, uint64_t img_size, int flags, bool quiet,
Error **errp)
{
QemuOptsList *create_opts = NULL;
QemuOpts *opts = NULL;
const char *backing_fmt, *backing_file;
int64_t size;
BlockDriver *drv, *proto_drv;
Error *local_err = NULL;
int ret = 0;
GLOBAL_STATE_CODE();
/* Find driver and parse its options */
drv = bdrv_find_format(fmt);
if (!drv) {
error_setg(errp, "Unknown file format '%s'", fmt);
return;
}
proto_drv = bdrv_find_protocol(filename, true, errp);
if (!proto_drv) {
return;
}
if (!drv->create_opts) {
error_setg(errp, "Format driver '%s' does not support image creation",
drv->format_name);
return;
}
if (!proto_drv->create_opts) {
error_setg(errp, "Protocol driver '%s' does not support image creation",
proto_drv->format_name);
return;
}
aio_context_acquire(qemu_get_aio_context());
/* Create parameter list */
create_opts = qemu_opts_append(create_opts, drv->create_opts);
create_opts = qemu_opts_append(create_opts, proto_drv->create_opts);
opts = qemu_opts_create(create_opts, NULL, 0, &error_abort);
/* Parse -o options */
if (options) {
if (!qemu_opts_do_parse(opts, options, NULL, errp)) {
goto out;
}
}
if (!qemu_opt_get(opts, BLOCK_OPT_SIZE)) {
qemu_opt_set_number(opts, BLOCK_OPT_SIZE, img_size, &error_abort);
} else if (img_size != UINT64_C(-1)) {
error_setg(errp, "The image size must be specified only once");
goto out;
}
if (base_filename) {
if (!qemu_opt_set(opts, BLOCK_OPT_BACKING_FILE, base_filename,
NULL)) {
error_setg(errp, "Backing file not supported for file format '%s'",
fmt);
goto out;
}
}
if (base_fmt) {
if (!qemu_opt_set(opts, BLOCK_OPT_BACKING_FMT, base_fmt, NULL)) {
error_setg(errp, "Backing file format not supported for file "
"format '%s'", fmt);
goto out;
}
}
backing_file = qemu_opt_get(opts, BLOCK_OPT_BACKING_FILE);
if (backing_file) {
if (!strcmp(filename, backing_file)) {
error_setg(errp, "Error: Trying to create an image with the "
"same filename as the backing file");
goto out;
}
if (backing_file[0] == '\0') {
error_setg(errp, "Expected backing file name, got empty string");
goto out;
}
}
backing_fmt = qemu_opt_get(opts, BLOCK_OPT_BACKING_FMT);
/* The size for the image must always be specified, unless we have a backing
* file and we have not been forbidden from opening it. */
size = qemu_opt_get_size(opts, BLOCK_OPT_SIZE, img_size);
if (backing_file && !(flags & BDRV_O_NO_BACKING)) {
BlockDriverState *bs;
char *full_backing;
int back_flags;
QDict *backing_options = NULL;
full_backing =
bdrv_get_full_backing_filename_from_filename(filename, backing_file,
&local_err);
if (local_err) {
goto out;
}
assert(full_backing);
/*
* No need to do I/O here, which allows us to open encrypted
* backing images without needing the secret
*/
back_flags = flags;
back_flags &= ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);
back_flags |= BDRV_O_NO_IO;
backing_options = qdict_new();
if (backing_fmt) {
qdict_put_str(backing_options, "driver", backing_fmt);
}
qdict_put_bool(backing_options, BDRV_OPT_FORCE_SHARE, true);
bs = bdrv_open(full_backing, NULL, backing_options, back_flags,
&local_err);
g_free(full_backing);
if (!bs) {
error_append_hint(&local_err, "Could not open backing image.\n");
goto out;
} else {
if (!backing_fmt) {
error_setg(&local_err,
"Backing file specified without backing format");
error_append_hint(&local_err, "Detected format of %s.\n",
bs->drv->format_name);
goto out;
}
if (size == -1) {
/* Opened BS, have no size */
size = bdrv_getlength(bs);
if (size < 0) {
error_setg_errno(errp, -size, "Could not get size of '%s'",
backing_file);
bdrv_unref(bs);
goto out;
}
qemu_opt_set_number(opts, BLOCK_OPT_SIZE, size, &error_abort);
}
bdrv_unref(bs);
}
/* (backing_file && !(flags & BDRV_O_NO_BACKING)) */
} else if (backing_file && !backing_fmt) {
error_setg(&local_err,
"Backing file specified without backing format");
goto out;
}
if (size == -1) {
error_setg(errp, "Image creation needs a size parameter");
goto out;
}
if (!quiet) {
printf("Formatting '%s', fmt=%s ", filename, fmt);
qemu_opts_print(opts, " ");
puts("");
fflush(stdout);
}
ret = bdrv_create(drv, filename, opts, &local_err);
if (ret == -EFBIG) {
/* This is generally a better message than whatever the driver would
* deliver (especially because of the cluster_size_hint), since that
* is most probably not much different from "image too large". */
const char *cluster_size_hint = "";
if (qemu_opt_get_size(opts, BLOCK_OPT_CLUSTER_SIZE, 0)) {
cluster_size_hint = " (try using a larger cluster size)";
}
error_setg(errp, "The image size is too large for file format '%s'"
"%s", fmt, cluster_size_hint);
error_free(local_err);
local_err = NULL;
}
out:
qemu_opts_del(opts);
qemu_opts_free(create_opts);
error_propagate(errp, local_err);
aio_context_release(qemu_get_aio_context());
}
AioContext *bdrv_get_aio_context(BlockDriverState *bs)
{
IO_CODE();
return bs ? bs->aio_context : qemu_get_aio_context();
}
AioContext *coroutine_fn bdrv_co_enter(BlockDriverState *bs)
{
Coroutine *self = qemu_coroutine_self();
AioContext *old_ctx = qemu_coroutine_get_aio_context(self);
AioContext *new_ctx;
IO_CODE();
/*
* Increase bs->in_flight to ensure that this operation is completed before
* moving the node to a different AioContext. Read new_ctx only afterwards.
*/
bdrv_inc_in_flight(bs);
new_ctx = bdrv_get_aio_context(bs);
aio_co_reschedule_self(new_ctx);
return old_ctx;
}
void coroutine_fn bdrv_co_leave(BlockDriverState *bs, AioContext *old_ctx)
{
IO_CODE();
aio_co_reschedule_self(old_ctx);
bdrv_dec_in_flight(bs);
}
void coroutine_fn bdrv_co_lock(BlockDriverState *bs)
{
AioContext *ctx = bdrv_get_aio_context(bs);
/* In the main thread, bs->aio_context won't change concurrently */
assert(qemu_get_current_aio_context() == qemu_get_aio_context());
/*
* We're in coroutine context, so we already hold the lock of the main
* loop AioContext. Don't lock it twice to avoid deadlocks.
*/
assert(qemu_in_coroutine());
if (ctx != qemu_get_aio_context()) {
aio_context_acquire(ctx);
}
}
void coroutine_fn bdrv_co_unlock(BlockDriverState *bs)
{
AioContext *ctx = bdrv_get_aio_context(bs);
assert(qemu_in_coroutine());
if (ctx != qemu_get_aio_context()) {
aio_context_release(ctx);
}
}
static void bdrv_do_remove_aio_context_notifier(BdrvAioNotifier *ban)
{
GLOBAL_STATE_CODE();
QLIST_REMOVE(ban, list);
g_free(ban);
}
static void bdrv_detach_aio_context(BlockDriverState *bs)
{
BdrvAioNotifier *baf, *baf_tmp;
assert(!bs->walking_aio_notifiers);
GLOBAL_STATE_CODE();
bs->walking_aio_notifiers = true;
QLIST_FOREACH_SAFE(baf, &bs->aio_notifiers, list, baf_tmp) {
if (baf->deleted) {
bdrv_do_remove_aio_context_notifier(baf);
} else {
baf->detach_aio_context(baf->opaque);
}
}
/* Never mind iterating again to check for ->deleted. bdrv_close() will
* remove remaining aio notifiers if we aren't called again.
*/
bs->walking_aio_notifiers = false;
if (bs->drv && bs->drv->bdrv_detach_aio_context) {
bs->drv->bdrv_detach_aio_context(bs);
}
bs->aio_context = NULL;
}
static void bdrv_attach_aio_context(BlockDriverState *bs,
AioContext *new_context)
{
BdrvAioNotifier *ban, *ban_tmp;
GLOBAL_STATE_CODE();
bs->aio_context = new_context;
if (bs->drv && bs->drv->bdrv_attach_aio_context) {
bs->drv->bdrv_attach_aio_context(bs, new_context);
}
assert(!bs->walking_aio_notifiers);
bs->walking_aio_notifiers = true;
QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_tmp) {
if (ban->deleted) {
bdrv_do_remove_aio_context_notifier(ban);
} else {
ban->attached_aio_context(new_context, ban->opaque);
}
}
bs->walking_aio_notifiers = false;
}
typedef struct BdrvStateSetAioContext {
AioContext *new_ctx;
BlockDriverState *bs;
} BdrvStateSetAioContext;
static bool bdrv_parent_change_aio_context(BdrvChild *c, AioContext *ctx,
GHashTable *visited,
Transaction *tran,
Error **errp)
{
GLOBAL_STATE_CODE();
if (g_hash_table_contains(visited, c)) {
return true;
}
g_hash_table_add(visited, c);
/*
* A BdrvChildClass that doesn't handle AioContext changes cannot
* tolerate any AioContext changes
*/
if (!c->klass->change_aio_ctx) {
char *user = bdrv_child_user_desc(c);
error_setg(errp, "Changing iothreads is not supported by %s", user);
g_free(user);
return false;
}
if (!c->klass->change_aio_ctx(c, ctx, visited, tran, errp)) {
assert(!errp || *errp);
return false;
}
return true;
}
bool bdrv_child_change_aio_context(BdrvChild *c, AioContext *ctx,
GHashTable *visited, Transaction *tran,
Error **errp)
{
GLOBAL_STATE_CODE();
if (g_hash_table_contains(visited, c)) {
return true;
}
g_hash_table_add(visited, c);
return bdrv_change_aio_context(c->bs, ctx, visited, tran, errp);
}
static void bdrv_set_aio_context_clean(void *opaque)
{
BdrvStateSetAioContext *state = (BdrvStateSetAioContext *) opaque;
BlockDriverState *bs = (BlockDriverState *) state->bs;
/* Paired with bdrv_drained_begin in bdrv_change_aio_context() */
bdrv_drained_end(bs);
g_free(state);
}
static void bdrv_set_aio_context_commit(void *opaque)
{
BdrvStateSetAioContext *state = (BdrvStateSetAioContext *) opaque;
BlockDriverState *bs = (BlockDriverState *) state->bs;
AioContext *new_context = state->new_ctx;
AioContext *old_context = bdrv_get_aio_context(bs);
/*
* Take the old AioContex when detaching it from bs.
* At this point, new_context lock is already acquired, and we are now
* also taking old_context. This is safe as long as bdrv_detach_aio_context
* does not call AIO_POLL_WHILE().
*/
if (old_context != qemu_get_aio_context()) {
aio_context_acquire(old_context);
}
bdrv_detach_aio_context(bs);
if (old_context != qemu_get_aio_context()) {
aio_context_release(old_context);
}
bdrv_attach_aio_context(bs, new_context);
}
static TransactionActionDrv set_aio_context = {
.commit = bdrv_set_aio_context_commit,
.clean = bdrv_set_aio_context_clean,
};
/*
* Changes the AioContext used for fd handlers, timers, and BHs by this
* BlockDriverState and all its children and parents.
*
* Must be called from the main AioContext.
*
* The caller must own the AioContext lock for the old AioContext of bs, but it
* must not own the AioContext lock for new_context (unless new_context is the
* same as the current context of bs).
*
* @visited will accumulate all visited BdrvChild objects. The caller is
* responsible for freeing the list afterwards.
*/
static bool bdrv_change_aio_context(BlockDriverState *bs, AioContext *ctx,
GHashTable *visited, Transaction *tran,
Error **errp)
{
BdrvChild *c;
BdrvStateSetAioContext *state;
GLOBAL_STATE_CODE();
if (bdrv_get_aio_context(bs) == ctx) {
return true;
}
bdrv_graph_rdlock_main_loop();
QLIST_FOREACH(c, &bs->parents, next_parent) {
if (!bdrv_parent_change_aio_context(c, ctx, visited, tran, errp)) {
bdrv_graph_rdunlock_main_loop();
return false;
}
}
QLIST_FOREACH(c, &bs->children, next) {
if (!bdrv_child_change_aio_context(c, ctx, visited, tran, errp)) {
bdrv_graph_rdunlock_main_loop();
return false;
}
}
bdrv_graph_rdunlock_main_loop();
state = g_new(BdrvStateSetAioContext, 1);
*state = (BdrvStateSetAioContext) {
.new_ctx = ctx,
.bs = bs,
};
/* Paired with bdrv_drained_end in bdrv_set_aio_context_clean() */
bdrv_drained_begin(bs);
tran_add(tran, &set_aio_context, state);
return true;
}
/*
* Change bs's and recursively all of its parents' and children's AioContext
* to the given new context, returning an error if that isn't possible.
*
* If ignore_child is not NULL, that child (and its subgraph) will not
* be touched.
*
* This function still requires the caller to take the bs current
* AioContext lock, otherwise draining will fail since AIO_WAIT_WHILE
* assumes the lock is always held if bs is in another AioContext.
* For the same reason, it temporarily also holds the new AioContext, since
* bdrv_drained_end calls BDRV_POLL_WHILE that assumes the lock is taken too.
* Therefore the new AioContext lock must not be taken by the caller.
*/
int bdrv_try_change_aio_context(BlockDriverState *bs, AioContext *ctx,
BdrvChild *ignore_child, Error **errp)
{
Transaction *tran;
GHashTable *visited;
int ret;
AioContext *old_context = bdrv_get_aio_context(bs);
GLOBAL_STATE_CODE();
/*
* Recursion phase: go through all nodes of the graph.
* Take care of checking that all nodes support changing AioContext
* and drain them, building a linear list of callbacks to run if everything
* is successful (the transaction itself).
*/
tran = tran_new();
visited = g_hash_table_new(NULL, NULL);
if (ignore_child) {
g_hash_table_add(visited, ignore_child);
}
ret = bdrv_change_aio_context(bs, ctx, visited, tran, errp);
g_hash_table_destroy(visited);
/*
* Linear phase: go through all callbacks collected in the transaction.
* Run all callbacks collected in the recursion to switch all nodes
* AioContext lock (transaction commit), or undo all changes done in the
* recursion (transaction abort).
*/
if (!ret) {
/* Just run clean() callbacks. No AioContext changed. */
tran_abort(tran);
return -EPERM;
}
/*
* Release old AioContext, it won't be needed anymore, as all
* bdrv_drained_begin() have been called already.
*/
if (qemu_get_aio_context() != old_context) {
aio_context_release(old_context);
}
/*
* Acquire new AioContext since bdrv_drained_end() is going to be called
* after we switched all nodes in the new AioContext, and the function
* assumes that the lock of the bs is always taken.
*/
if (qemu_get_aio_context() != ctx) {
aio_context_acquire(ctx);
}
tran_commit(tran);
if (qemu_get_aio_context() != ctx) {
aio_context_release(ctx);
}
/* Re-acquire the old AioContext, since the caller takes and releases it. */
if (qemu_get_aio_context() != old_context) {
aio_context_acquire(old_context);
}
return 0;
}
void bdrv_add_aio_context_notifier(BlockDriverState *bs,
void (*attached_aio_context)(AioContext *new_context, void *opaque),
void (*detach_aio_context)(void *opaque), void *opaque)
{
BdrvAioNotifier *ban = g_new(BdrvAioNotifier, 1);
*ban = (BdrvAioNotifier){
.attached_aio_context = attached_aio_context,
.detach_aio_context = detach_aio_context,
.opaque = opaque
};
GLOBAL_STATE_CODE();
QLIST_INSERT_HEAD(&bs->aio_notifiers, ban, list);
}
void bdrv_remove_aio_context_notifier(BlockDriverState *bs,
void (*attached_aio_context)(AioContext *,
void *),
void (*detach_aio_context)(void *),
void *opaque)
{
BdrvAioNotifier *ban, *ban_next;
GLOBAL_STATE_CODE();
QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) {
if (ban->attached_aio_context == attached_aio_context &&
ban->detach_aio_context == detach_aio_context &&
ban->opaque == opaque &&
ban->deleted == false)
{
if (bs->walking_aio_notifiers) {
ban->deleted = true;
} else {
bdrv_do_remove_aio_context_notifier(ban);
}
return;
}
}
abort();
}
int bdrv_amend_options(BlockDriverState *bs, QemuOpts *opts,
BlockDriverAmendStatusCB *status_cb, void *cb_opaque,
bool force,
Error **errp)
{
GLOBAL_STATE_CODE();
if (!bs->drv) {
error_setg(errp, "Node is ejected");
return -ENOMEDIUM;
}
if (!bs->drv->bdrv_amend_options) {
error_setg(errp, "Block driver '%s' does not support option amendment",
bs->drv->format_name);
return -ENOTSUP;
}
return bs->drv->bdrv_amend_options(bs, opts, status_cb,
cb_opaque, force, errp);
}
/*
* This function checks whether the given @to_replace is allowed to be
* replaced by a node that always shows the same data as @bs. This is
* used for example to verify whether the mirror job can replace
* @to_replace by the target mirrored from @bs.
* To be replaceable, @bs and @to_replace may either be guaranteed to
* always show the same data (because they are only connected through
* filters), or some driver may allow replacing one of its children
* because it can guarantee that this child's data is not visible at
* all (for example, for dissenting quorum children that have no other
* parents).
*/
bool bdrv_recurse_can_replace(BlockDriverState *bs,
BlockDriverState *to_replace)
{
BlockDriverState *filtered;
GLOBAL_STATE_CODE();
if (!bs || !bs->drv) {
return false;
}
if (bs == to_replace) {
return true;
}
/* See what the driver can do */
if (bs->drv->bdrv_recurse_can_replace) {
return bs->drv->bdrv_recurse_can_replace(bs, to_replace);
}
/* For filters without an own implementation, we can recurse on our own */
filtered = bdrv_filter_bs(bs);
if (filtered) {
return bdrv_recurse_can_replace(filtered, to_replace);
}
/* Safe default */
return false;
}
/*
* Check whether the given @node_name can be replaced by a node that
* has the same data as @parent_bs. If so, return @node_name's BDS;
* NULL otherwise.
*
* @node_name must be a (recursive) *child of @parent_bs (or this
* function will return NULL).
*
* The result (whether the node can be replaced or not) is only valid
* for as long as no graph or permission changes occur.
*/
BlockDriverState *check_to_replace_node(BlockDriverState *parent_bs,
const char *node_name, Error **errp)
{
BlockDriverState *to_replace_bs = bdrv_find_node(node_name);
AioContext *aio_context;
GLOBAL_STATE_CODE();
if (!to_replace_bs) {
error_setg(errp, "Failed to find node with node-name='%s'", node_name);
return NULL;
}
aio_context = bdrv_get_aio_context(to_replace_bs);
aio_context_acquire(aio_context);
if (bdrv_op_is_blocked(to_replace_bs, BLOCK_OP_TYPE_REPLACE, errp)) {
to_replace_bs = NULL;
goto out;
}
/* We don't want arbitrary node of the BDS chain to be replaced only the top
* most non filter in order to prevent data corruption.
* Another benefit is that this tests exclude backing files which are
* blocked by the backing blockers.
*/
if (!bdrv_recurse_can_replace(parent_bs, to_replace_bs)) {
error_setg(errp, "Cannot replace '%s' by a node mirrored from '%s', "
"because it cannot be guaranteed that doing so would not "
"lead to an abrupt change of visible data",
node_name, parent_bs->node_name);
to_replace_bs = NULL;
goto out;
}
out:
aio_context_release(aio_context);
return to_replace_bs;
}
/**
* Iterates through the list of runtime option keys that are said to
* be "strong" for a BDS. An option is called "strong" if it changes
* a BDS's data. For example, the null block driver's "size" and
* "read-zeroes" options are strong, but its "latency-ns" option is
* not.
*
* If a key returned by this function ends with a dot, all options
* starting with that prefix are strong.
*/
static const char *const *strong_options(BlockDriverState *bs,
const char *const *curopt)
{
static const char *const global_options[] = {
"driver", "filename", NULL
};
if (!curopt) {
return &global_options[0];
}
curopt++;
if (curopt == &global_options[ARRAY_SIZE(global_options) - 1] && bs->drv) {
curopt = bs->drv->strong_runtime_opts;
}
return (curopt && *curopt) ? curopt : NULL;
}
/**
* Copies all strong runtime options from bs->options to the given
* QDict. The set of strong option keys is determined by invoking
* strong_options().
*
* Returns true iff any strong option was present in bs->options (and
* thus copied to the target QDict) with the exception of "filename"
* and "driver". The caller is expected to use this value to decide
* whether the existence of strong options prevents the generation of
* a plain filename.
*/
static bool append_strong_runtime_options(QDict *d, BlockDriverState *bs)
{
bool found_any = false;
const char *const *option_name = NULL;
if (!bs->drv) {
return false;
}
while ((option_name = strong_options(bs, option_name))) {
bool option_given = false;
assert(strlen(*option_name) > 0);
if ((*option_name)[strlen(*option_name) - 1] != '.') {
QObject *entry = qdict_get(bs->options, *option_name);
if (!entry) {
continue;
}
qdict_put_obj(d, *option_name, qobject_ref(entry));
option_given = true;
} else {
const QDictEntry *entry;
for (entry = qdict_first(bs->options); entry;
entry = qdict_next(bs->options, entry))
{
if (strstart(qdict_entry_key(entry), *option_name, NULL)) {
qdict_put_obj(d, qdict_entry_key(entry),
qobject_ref(qdict_entry_value(entry)));
option_given = true;
}
}
}
/* While "driver" and "filename" need to be included in a JSON filename,
* their existence does not prohibit generation of a plain filename. */
if (!found_any && option_given &&
strcmp(*option_name, "driver") && strcmp(*option_name, "filename"))
{
found_any = true;
}
}
if (!qdict_haskey(d, "driver")) {
/* Drivers created with bdrv_new_open_driver() may not have a
* @driver option. Add it here. */
qdict_put_str(d, "driver", bs->drv->format_name);
}
return found_any;
}
/* Note: This function may return false positives; it may return true
* even if opening the backing file specified by bs's image header
* would result in exactly bs->backing. */
static bool GRAPH_RDLOCK bdrv_backing_overridden(BlockDriverState *bs)
{
GLOBAL_STATE_CODE();
if (bs->backing) {
return strcmp(bs->auto_backing_file,
bs->backing->bs->filename);
} else {
/* No backing BDS, so if the image header reports any backing
* file, it must have been suppressed */
return bs->auto_backing_file[0] != '\0';
}
}
/* Updates the following BDS fields:
* - exact_filename: A filename which may be used for opening a block device
* which (mostly) equals the given BDS (even without any
* other options; so reading and writing must return the same
* results, but caching etc. may be different)
* - full_open_options: Options which, when given when opening a block device
* (without a filename), result in a BDS (mostly)
* equalling the given one
* - filename: If exact_filename is set, it is copied here. Otherwise,
* full_open_options is converted to a JSON object, prefixed with
* "json:" (for use through the JSON pseudo protocol) and put here.
*/
void bdrv_refresh_filename(BlockDriverState *bs)
{
BlockDriver *drv = bs->drv;
BdrvChild *child;
BlockDriverState *primary_child_bs;
QDict *opts;
bool backing_overridden;
bool generate_json_filename; /* Whether our default implementation should
fill exact_filename (false) or not (true) */
GLOBAL_STATE_CODE();
if (!drv) {
return;
}
/* This BDS's file name may depend on any of its children's file names, so
* refresh those first */
QLIST_FOREACH(child, &bs->children, next) {
bdrv_refresh_filename(child->bs);
}
if (bs->implicit) {
/* For implicit nodes, just copy everything from the single child */
child = QLIST_FIRST(&bs->children);
assert(QLIST_NEXT(child, next) == NULL);
pstrcpy(bs->exact_filename, sizeof(bs->exact_filename),
child->bs->exact_filename);
pstrcpy(bs->filename, sizeof(bs->filename), child->bs->filename);
qobject_unref(bs->full_open_options);
bs->full_open_options = qobject_ref(child->bs->full_open_options);
return;
}
backing_overridden = bdrv_backing_overridden(bs);
if (bs->open_flags & BDRV_O_NO_IO) {
/* Without I/O, the backing file does not change anything.
* Therefore, in such a case (primarily qemu-img), we can
* pretend the backing file has not been overridden even if
* it technically has been. */
backing_overridden = false;
}
/* Gather the options QDict */
opts = qdict_new();
generate_json_filename = append_strong_runtime_options(opts, bs);
generate_json_filename |= backing_overridden;
if (drv->bdrv_gather_child_options) {
/* Some block drivers may not want to present all of their children's
* options, or name them differently from BdrvChild.name */
drv->bdrv_gather_child_options(bs, opts, backing_overridden);
} else {
QLIST_FOREACH(child, &bs->children, next) {
if (child == bs->backing && !backing_overridden) {
/* We can skip the backing BDS if it has not been overridden */
continue;
}
qdict_put(opts, child->name,
qobject_ref(child->bs->full_open_options));
}
if (backing_overridden && !bs->backing) {
/* Force no backing file */
qdict_put_null(opts, "backing");
}
}
qobject_unref(bs->full_open_options);
bs->full_open_options = opts;
primary_child_bs = bdrv_primary_bs(bs);
if (drv->bdrv_refresh_filename) {
/* Obsolete information is of no use here, so drop the old file name
* information before refreshing it */
bs->exact_filename[0] = '\0';
drv->bdrv_refresh_filename(bs);
} else if (primary_child_bs) {
/*
* Try to reconstruct valid information from the underlying
* file -- this only works for format nodes (filter nodes
* cannot be probed and as such must be selected by the user
* either through an options dict, or through a special
* filename which the filter driver must construct in its
* .bdrv_refresh_filename() implementation).
*/
bs->exact_filename[0] = '\0';
/*
* We can use the underlying file's filename if:
* - it has a filename,
* - the current BDS is not a filter,
* - the file is a protocol BDS, and
* - opening that file (as this BDS's format) will automatically create
* the BDS tree we have right now, that is:
* - the user did not significantly change this BDS's behavior with
* some explicit (strong) options
* - no non-file child of this BDS has been overridden by the user
* Both of these conditions are represented by generate_json_filename.
*/
if (primary_child_bs->exact_filename[0] &&
primary_child_bs->drv->bdrv_file_open &&
!drv->is_filter && !generate_json_filename)
{
strcpy(bs->exact_filename, primary_child_bs->exact_filename);
}
}
if (bs->exact_filename[0]) {
pstrcpy(bs->filename, sizeof(bs->filename), bs->exact_filename);
} else {
GString *json = qobject_to_json(QOBJECT(bs->full_open_options));
if (snprintf(bs->filename, sizeof(bs->filename), "json:%s",
json->str) >= sizeof(bs->filename)) {
/* Give user a hint if we truncated things. */
strcpy(bs->filename + sizeof(bs->filename) - 4, "...");
}
g_string_free(json, true);
}
}
char *bdrv_dirname(BlockDriverState *bs, Error **errp)
{
BlockDriver *drv = bs->drv;
BlockDriverState *child_bs;
GLOBAL_STATE_CODE();
if (!drv) {
error_setg(errp, "Node '%s' is ejected", bs->node_name);
return NULL;
}
if (drv->bdrv_dirname) {
return drv->bdrv_dirname(bs, errp);
}
child_bs = bdrv_primary_bs(bs);
if (child_bs) {
return bdrv_dirname(child_bs, errp);
}
bdrv_refresh_filename(bs);
if (bs->exact_filename[0] != '\0') {
return path_combine(bs->exact_filename, "");
}
error_setg(errp, "Cannot generate a base directory for %s nodes",
drv->format_name);
return NULL;
}
/*
* Hot add/remove a BDS's child. So the user can take a child offline when
* it is broken and take a new child online
*/
void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
Error **errp)
{
GLOBAL_STATE_CODE();
if (!parent_bs->drv || !parent_bs->drv->bdrv_add_child) {
error_setg(errp, "The node %s does not support adding a child",
bdrv_get_device_or_node_name(parent_bs));
return;
}
/*
* Non-zoned block drivers do not follow zoned storage constraints
* (i.e. sequential writes to zones). Refuse mixing zoned and non-zoned
* drivers in a graph.
*/
if (!parent_bs->drv->supports_zoned_children &&
child_bs->bl.zoned == BLK_Z_HM) {
/*
* The host-aware model allows zoned storage constraints and random
* write. Allow mixing host-aware and non-zoned drivers. Using
* host-aware device as a regular device.
*/
error_setg(errp, "Cannot add a %s child to a %s parent",
child_bs->bl.zoned == BLK_Z_HM ? "zoned" : "non-zoned",
parent_bs->drv->supports_zoned_children ?
"support zoned children" : "not support zoned children");
return;
}
if (!QLIST_EMPTY(&child_bs->parents)) {
error_setg(errp, "The node %s already has a parent",
child_bs->node_name);
return;
}
parent_bs->drv->bdrv_add_child(parent_bs, child_bs, errp);
}
void bdrv_del_child(BlockDriverState *parent_bs, BdrvChild *child, Error **errp)
{
BdrvChild *tmp;
GLOBAL_STATE_CODE();
if (!parent_bs->drv || !parent_bs->drv->bdrv_del_child) {
error_setg(errp, "The node %s does not support removing a child",
bdrv_get_device_or_node_name(parent_bs));
return;
}
QLIST_FOREACH(tmp, &parent_bs->children, next) {
if (tmp == child) {
break;
}
}
if (!tmp) {
error_setg(errp, "The node %s does not have a child named %s",
bdrv_get_device_or_node_name(parent_bs),
bdrv_get_device_or_node_name(child->bs));
return;
}
parent_bs->drv->bdrv_del_child(parent_bs, child, errp);
}
int bdrv_make_empty(BdrvChild *c, Error **errp)
{
BlockDriver *drv = c->bs->drv;
int ret;
GLOBAL_STATE_CODE();
assert(c->perm & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED));
if (!drv->bdrv_make_empty) {
error_setg(errp, "%s does not support emptying nodes",
drv->format_name);
return -ENOTSUP;
}
ret = drv->bdrv_make_empty(c->bs);
if (ret < 0) {
error_setg_errno(errp, -ret, "Failed to empty %s",
c->bs->filename);
return ret;
}
return 0;
}
/*
* Return the child that @bs acts as an overlay for, and from which data may be
* copied in COW or COR operations. Usually this is the backing file.
*/
BdrvChild *bdrv_cow_child(BlockDriverState *bs)
{
IO_CODE();
if (!bs || !bs->drv) {
return NULL;
}
if (bs->drv->is_filter) {
return NULL;
}
if (!bs->backing) {
return NULL;
}
assert(bs->backing->role & BDRV_CHILD_COW);
return bs->backing;
}
/*
* If @bs acts as a filter for exactly one of its children, return
* that child.
*/
BdrvChild *bdrv_filter_child(BlockDriverState *bs)
{
BdrvChild *c;
IO_CODE();
if (!bs || !bs->drv) {
return NULL;
}
if (!bs->drv->is_filter) {
return NULL;
}
/* Only one of @backing or @file may be used */
assert(!(bs->backing && bs->file));
c = bs->backing ?: bs->file;
if (!c) {
return NULL;
}
assert(c->role & BDRV_CHILD_FILTERED);
return c;
}
/*
* Return either the result of bdrv_cow_child() or bdrv_filter_child(),
* whichever is non-NULL.
*
* Return NULL if both are NULL.
*/
BdrvChild *bdrv_filter_or_cow_child(BlockDriverState *bs)
{
BdrvChild *cow_child = bdrv_cow_child(bs);
BdrvChild *filter_child = bdrv_filter_child(bs);
IO_CODE();
/* Filter nodes cannot have COW backing files */
assert(!(cow_child && filter_child));
return cow_child ?: filter_child;
}
/*
* Return the primary child of this node: For filters, that is the
* filtered child. For other nodes, that is usually the child storing
* metadata.
* (A generally more helpful description is that this is (usually) the
* child that has the same filename as @bs.)
*
* Drivers do not necessarily have a primary child; for example quorum
* does not.
*/
BdrvChild *bdrv_primary_child(BlockDriverState *bs)
{
BdrvChild *c, *found = NULL;
IO_CODE();
QLIST_FOREACH(c, &bs->children, next) {
if (c->role & BDRV_CHILD_PRIMARY) {
assert(!found);
found = c;
}
}
return found;
}
static BlockDriverState * GRAPH_RDLOCK
bdrv_do_skip_filters(BlockDriverState *bs, bool stop_on_explicit_filter)
{
BdrvChild *c;
if (!bs) {
return NULL;
}
while (!(stop_on_explicit_filter && !bs->implicit)) {
c = bdrv_filter_child(bs);
if (!c) {
/*
* A filter that is embedded in a working block graph must
* have a child. Assert this here so this function does
* not return a filter node that is not expected by the
* caller.
*/
assert(!bs->drv || !bs->drv->is_filter);
break;
}
bs = c->bs;
}
/*
* Note that this treats nodes with bs->drv == NULL as not being
* filters (bs->drv == NULL should be replaced by something else
* anyway).
* The advantage of this behavior is that this function will thus
* always return a non-NULL value (given a non-NULL @bs).
*/
return bs;
}
/*
* Return the first BDS that has not been added implicitly or that
* does not have a filtered child down the chain starting from @bs
* (including @bs itself).
*/
BlockDriverState *bdrv_skip_implicit_filters(BlockDriverState *bs)
{
GLOBAL_STATE_CODE();
return bdrv_do_skip_filters(bs, true);
}
/*
* Return the first BDS that does not have a filtered child down the
* chain starting from @bs (including @bs itself).
*/
BlockDriverState *bdrv_skip_filters(BlockDriverState *bs)
{
IO_CODE();
return bdrv_do_skip_filters(bs, false);
}
/*
* For a backing chain, return the first non-filter backing image of
* the first non-filter image.
*/
BlockDriverState *bdrv_backing_chain_next(BlockDriverState *bs)
{
IO_CODE();
return bdrv_skip_filters(bdrv_cow_bs(bdrv_skip_filters(bs)));
}
/**
* Check whether [offset, offset + bytes) overlaps with the cached
* block-status data region.
*
* If so, and @pnum is not NULL, set *pnum to `bsc.data_end - offset`,
* which is what bdrv_bsc_is_data()'s interface needs.
* Otherwise, *pnum is not touched.
*/
static bool bdrv_bsc_range_overlaps_locked(BlockDriverState *bs,
int64_t offset, int64_t bytes,
int64_t *pnum)
{
BdrvBlockStatusCache *bsc = qatomic_rcu_read(&bs->block_status_cache);
bool overlaps;
overlaps =
qatomic_read(&bsc->valid) &&
ranges_overlap(offset, bytes, bsc->data_start,
bsc->data_end - bsc->data_start);
if (overlaps && pnum) {
*pnum = bsc->data_end - offset;
}
return overlaps;
}
/**
* See block_int.h for this function's documentation.
*/
bool bdrv_bsc_is_data(BlockDriverState *bs, int64_t offset, int64_t *pnum)
{
IO_CODE();
RCU_READ_LOCK_GUARD();
return bdrv_bsc_range_overlaps_locked(bs, offset, 1, pnum);
}
/**
* See block_int.h for this function's documentation.
*/
void bdrv_bsc_invalidate_range(BlockDriverState *bs,
int64_t offset, int64_t bytes)
{
IO_CODE();
RCU_READ_LOCK_GUARD();
if (bdrv_bsc_range_overlaps_locked(bs, offset, bytes, NULL)) {
qatomic_set(&bs->block_status_cache->valid, false);
}
}
/**
* See block_int.h for this function's documentation.
*/
void bdrv_bsc_fill(BlockDriverState *bs, int64_t offset, int64_t bytes)
{
BdrvBlockStatusCache *new_bsc = g_new(BdrvBlockStatusCache, 1);
BdrvBlockStatusCache *old_bsc;
IO_CODE();
*new_bsc = (BdrvBlockStatusCache) {
.valid = true,
.data_start = offset,
.data_end = offset + bytes,
};
QEMU_LOCK_GUARD(&bs->bsc_modify_lock);
old_bsc = qatomic_rcu_read(&bs->block_status_cache);
qatomic_rcu_set(&bs->block_status_cache, new_bsc);
if (old_bsc) {
g_free_rcu(old_bsc, rcu);
}
}