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qemu / qemu / 0a8e1acd4dced15f2069df484df3c4d14c9534a9 / . / block-qcow2.c
blob: d99811d3ffbb250ef85b802b4717fb0ef01ed26f [file] [log] [blame]
/*
* Block driver for the QCOW version 2 format
*
* Copyright (c) 2004-2006 Fabrice Bellard
*
* 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-common.h"
#include "block_int.h"
#include <zlib.h>
#include "aes.h"
#include <assert.h>
/*
Differences with QCOW:
- Support for multiple incremental snapshots.
- Memory management by reference counts.
- Clusters which have a reference count of one have the bit
QCOW_OFLAG_COPIED to optimize write performance.
- Size of compressed clusters is stored in sectors to reduce bit usage
in the cluster offsets.
- Support for storing additional data (such as the VM state) in the
snapshots.
- If a backing store is used, the cluster size is not constrained
(could be backported to QCOW).
- L2 tables have always a size of one cluster.
*/
//#define DEBUG_ALLOC
//#define DEBUG_ALLOC2
//#define DEBUG_EXT
#define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
#define QCOW_VERSION 2
#define QCOW_CRYPT_NONE 0
#define QCOW_CRYPT_AES 1
#define QCOW_MAX_CRYPT_CLUSTERS 32
/* indicate that the refcount of the referenced cluster is exactly one. */
#define QCOW_OFLAG_COPIED (1LL << 63)
/* indicate that the cluster is compressed (they never have the copied flag) */
#define QCOW_OFLAG_COMPRESSED (1LL << 62)
#define REFCOUNT_SHIFT 1 /* refcount size is 2 bytes */
typedef struct QCowHeader {
uint32_t magic;
uint32_t version;
uint64_t backing_file_offset;
uint32_t backing_file_size;
uint32_t cluster_bits;
uint64_t size; /* in bytes */
uint32_t crypt_method;
uint32_t l1_size; /* XXX: save number of clusters instead ? */
uint64_t l1_table_offset;
uint64_t refcount_table_offset;
uint32_t refcount_table_clusters;
uint32_t nb_snapshots;
uint64_t snapshots_offset;
} QCowHeader;
typedef struct {
uint32_t magic;
uint32_t len;
} QCowExtension;
#define QCOW_EXT_MAGIC_END 0
#define QCOW_EXT_MAGIC_BACKING_FORMAT 0xE2792ACA
typedef struct __attribute__((packed)) QCowSnapshotHeader {
/* header is 8 byte aligned */
uint64_t l1_table_offset;
uint32_t l1_size;
uint16_t id_str_size;
uint16_t name_size;
uint32_t date_sec;
uint32_t date_nsec;
uint64_t vm_clock_nsec;
uint32_t vm_state_size;
uint32_t extra_data_size; /* for extension */
/* extra data follows */
/* id_str follows */
/* name follows */
} QCowSnapshotHeader;
#define L2_CACHE_SIZE 16
typedef struct QCowSnapshot {
uint64_t l1_table_offset;
uint32_t l1_size;
char *id_str;
char *name;
uint32_t vm_state_size;
uint32_t date_sec;
uint32_t date_nsec;
uint64_t vm_clock_nsec;
} QCowSnapshot;
typedef struct BDRVQcowState {
BlockDriverState *hd;
int cluster_bits;
int cluster_size;
int cluster_sectors;
int l2_bits;
int l2_size;
int l1_size;
int l1_vm_state_index;
int csize_shift;
int csize_mask;
uint64_t cluster_offset_mask;
uint64_t l1_table_offset;
uint64_t *l1_table;
uint64_t *l2_cache;
uint64_t l2_cache_offsets[L2_CACHE_SIZE];
uint32_t l2_cache_counts[L2_CACHE_SIZE];
uint8_t *cluster_cache;
uint8_t *cluster_data;
uint64_t cluster_cache_offset;
uint64_t *refcount_table;
uint64_t refcount_table_offset;
uint32_t refcount_table_size;
uint64_t refcount_block_cache_offset;
uint16_t *refcount_block_cache;
int64_t free_cluster_index;
int64_t free_byte_offset;
uint32_t crypt_method; /* current crypt method, 0 if no key yet */
uint32_t crypt_method_header;
AES_KEY aes_encrypt_key;
AES_KEY aes_decrypt_key;
uint64_t snapshots_offset;
int snapshots_size;
int nb_snapshots;
QCowSnapshot *snapshots;
} BDRVQcowState;
static int decompress_cluster(BDRVQcowState *s, uint64_t cluster_offset);
static int qcow_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors);
static int qcow_read_snapshots(BlockDriverState *bs);
static void qcow_free_snapshots(BlockDriverState *bs);
static int refcount_init(BlockDriverState *bs);
static void refcount_close(BlockDriverState *bs);
static int get_refcount(BlockDriverState *bs, int64_t cluster_index);
static int update_cluster_refcount(BlockDriverState *bs,
int64_t cluster_index,
int addend);
static void update_refcount(BlockDriverState *bs,
int64_t offset, int64_t length,
int addend);
static int64_t alloc_clusters(BlockDriverState *bs, int64_t size);
static int64_t alloc_bytes(BlockDriverState *bs, int size);
static void free_clusters(BlockDriverState *bs,
int64_t offset, int64_t size);
#ifdef DEBUG_ALLOC
static void check_refcounts(BlockDriverState *bs);
#endif
static int qcow_probe(const uint8_t *buf, int buf_size, const char *filename)
{
const QCowHeader *cow_header = (const void *)buf;
if (buf_size >= sizeof(QCowHeader) &&
be32_to_cpu(cow_header->magic) == QCOW_MAGIC &&
be32_to_cpu(cow_header->version) == QCOW_VERSION)
return 100;
else
return 0;
}
/*
* read qcow2 extension and fill bs
* start reading from start_offset
* finish reading upon magic of value 0 or when end_offset reached
* unknown magic is skipped (future extension this version knows nothing about)
* return 0 upon success, non-0 otherwise
*/
static int qcow_read_extensions(BlockDriverState *bs, uint64_t start_offset,
uint64_t end_offset)
{
BDRVQcowState *s = bs->opaque;
QCowExtension ext;
uint64_t offset;
#ifdef DEBUG_EXT
printf("qcow_read_extensions: start=%ld end=%ld\n", start_offset, end_offset);
#endif
offset = start_offset;
while (offset < end_offset) {
#ifdef DEBUG_EXT
/* Sanity check */
if (offset > s->cluster_size)
printf("qcow_handle_extension: suspicious offset %lu\n", offset);
printf("attemting to read extended header in offset %lu\n", offset);
#endif
if (bdrv_pread(s->hd, offset, &ext, sizeof(ext)) != sizeof(ext)) {
fprintf(stderr, "qcow_handle_extension: ERROR: pread fail from offset %llu\n",
(unsigned long long)offset);
return 1;
}
be32_to_cpus(&ext.magic);
be32_to_cpus(&ext.len);
offset += sizeof(ext);
#ifdef DEBUG_EXT
printf("ext.magic = 0x%x\n", ext.magic);
#endif
switch (ext.magic) {
case QCOW_EXT_MAGIC_END:
return 0;
case QCOW_EXT_MAGIC_BACKING_FORMAT:
if (ext.len >= sizeof(bs->backing_format)) {
fprintf(stderr, "ERROR: ext_backing_format: len=%u too large"
" (>=%zu)\n",
ext.len, sizeof(bs->backing_format));
return 2;
}
if (bdrv_pread(s->hd, offset , bs->backing_format,
ext.len) != ext.len)
return 3;
bs->backing_format[ext.len] = '\0';
#ifdef DEBUG_EXT
printf("Qcow2: Got format extension %s\n", bs->backing_format);
#endif
offset += ((ext.len + 7) & ~7);
break;
default:
/* unknown magic -- just skip it */
offset += ((ext.len + 7) & ~7);
break;
}
}
return 0;
}
static int qcow_open(BlockDriverState *bs, const char *filename, int flags)
{
BDRVQcowState *s = bs->opaque;
int len, i, shift, ret;
QCowHeader header;
uint64_t ext_end;
/* Performance is terrible right now with cache=writethrough due mainly
* to reference count updates. If the user does not explicitly specify
* a caching type, force to writeback caching.
*/
if ((flags & BDRV_O_CACHE_DEF)) {
flags |= BDRV_O_CACHE_WB;
flags &= ~BDRV_O_CACHE_DEF;
}
ret = bdrv_file_open(&s->hd, filename, flags);
if (ret < 0)
return ret;
if (bdrv_pread(s->hd, 0, &header, sizeof(header)) != sizeof(header))
goto fail;
be32_to_cpus(&header.magic);
be32_to_cpus(&header.version);
be64_to_cpus(&header.backing_file_offset);
be32_to_cpus(&header.backing_file_size);
be64_to_cpus(&header.size);
be32_to_cpus(&header.cluster_bits);
be32_to_cpus(&header.crypt_method);
be64_to_cpus(&header.l1_table_offset);
be32_to_cpus(&header.l1_size);
be64_to_cpus(&header.refcount_table_offset);
be32_to_cpus(&header.refcount_table_clusters);
be64_to_cpus(&header.snapshots_offset);
be32_to_cpus(&header.nb_snapshots);
if (header.magic != QCOW_MAGIC || header.version != QCOW_VERSION)
goto fail;
if (header.size <= 1 ||
header.cluster_bits < 9 ||
header.cluster_bits > 16)
goto fail;
if (header.crypt_method > QCOW_CRYPT_AES)
goto fail;
s->crypt_method_header = header.crypt_method;
if (s->crypt_method_header)
bs->encrypted = 1;
s->cluster_bits = header.cluster_bits;
s->cluster_size = 1 << s->cluster_bits;
s->cluster_sectors = 1 << (s->cluster_bits - 9);
s->l2_bits = s->cluster_bits - 3; /* L2 is always one cluster */
s->l2_size = 1 << s->l2_bits;
bs->total_sectors = header.size / 512;
s->csize_shift = (62 - (s->cluster_bits - 8));
s->csize_mask = (1 << (s->cluster_bits - 8)) - 1;
s->cluster_offset_mask = (1LL << s->csize_shift) - 1;
s->refcount_table_offset = header.refcount_table_offset;
s->refcount_table_size =
header.refcount_table_clusters << (s->cluster_bits - 3);
s->snapshots_offset = header.snapshots_offset;
s->nb_snapshots = header.nb_snapshots;
/* read the level 1 table */
s->l1_size = header.l1_size;
shift = s->cluster_bits + s->l2_bits;
s->l1_vm_state_index = (header.size + (1LL << shift) - 1) >> shift;
/* the L1 table must contain at least enough entries to put
header.size bytes */
if (s->l1_size < s->l1_vm_state_index)
goto fail;
s->l1_table_offset = header.l1_table_offset;
s->l1_table = qemu_malloc(s->l1_size * sizeof(uint64_t));
if (bdrv_pread(s->hd, s->l1_table_offset, s->l1_table, s->l1_size * sizeof(uint64_t)) !=
s->l1_size * sizeof(uint64_t))
goto fail;
for(i = 0;i < s->l1_size; i++) {
be64_to_cpus(&s->l1_table[i]);
}
/* alloc L2 cache */
s->l2_cache = qemu_malloc(s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
s->cluster_cache = qemu_malloc(s->cluster_size);
/* one more sector for decompressed data alignment */
s->cluster_data = qemu_malloc(QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size
+ 512);
s->cluster_cache_offset = -1;
if (refcount_init(bs) < 0)
goto fail;
/* read qcow2 extensions */
if (header.backing_file_offset)
ext_end = header.backing_file_offset;
else
ext_end = s->cluster_size;
if (qcow_read_extensions(bs, sizeof(header), ext_end))
goto fail;
/* read the backing file name */
if (header.backing_file_offset != 0) {
len = header.backing_file_size;
if (len > 1023)
len = 1023;
if (bdrv_pread(s->hd, header.backing_file_offset, bs->backing_file, len) != len)
goto fail;
bs->backing_file[len] = '\0';
}
if (qcow_read_snapshots(bs) < 0)
goto fail;
#ifdef DEBUG_ALLOC
check_refcounts(bs);
#endif
return 0;
fail:
qcow_free_snapshots(bs);
refcount_close(bs);
qemu_free(s->l1_table);
qemu_free(s->l2_cache);
qemu_free(s->cluster_cache);
qemu_free(s->cluster_data);
bdrv_delete(s->hd);
return -1;
}
static int qcow_set_key(BlockDriverState *bs, const char *key)
{
BDRVQcowState *s = bs->opaque;
uint8_t keybuf[16];
int len, i;
memset(keybuf, 0, 16);
len = strlen(key);
if (len > 16)
len = 16;
/* XXX: we could compress the chars to 7 bits to increase
entropy */
for(i = 0;i < len;i++) {
keybuf[i] = key[i];
}
s->crypt_method = s->crypt_method_header;
if (AES_set_encrypt_key(keybuf, 128, &s->aes_encrypt_key) != 0)
return -1;
if (AES_set_decrypt_key(keybuf, 128, &s->aes_decrypt_key) != 0)
return -1;
#if 0
/* test */
{
uint8_t in[16];
uint8_t out[16];
uint8_t tmp[16];
for(i=0;i<16;i++)
in[i] = i;
AES_encrypt(in, tmp, &s->aes_encrypt_key);
AES_decrypt(tmp, out, &s->aes_decrypt_key);
for(i = 0; i < 16; i++)
printf(" %02x", tmp[i]);
printf("\n");
for(i = 0; i < 16; i++)
printf(" %02x", out[i]);
printf("\n");
}
#endif
return 0;
}
/* The crypt function is compatible with the linux cryptoloop
algorithm for < 4 GB images. NOTE: out_buf == in_buf is
supported */
static void encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
uint8_t *out_buf, const uint8_t *in_buf,
int nb_sectors, int enc,
const AES_KEY *key)
{
union {
uint64_t ll[2];
uint8_t b[16];
} ivec;
int i;
for(i = 0; i < nb_sectors; i++) {
ivec.ll[0] = cpu_to_le64(sector_num);
ivec.ll[1] = 0;
AES_cbc_encrypt(in_buf, out_buf, 512, key,
ivec.b, enc);
sector_num++;
in_buf += 512;
out_buf += 512;
}
}
static int copy_sectors(BlockDriverState *bs, uint64_t start_sect,
uint64_t cluster_offset, int n_start, int n_end)
{
BDRVQcowState *s = bs->opaque;
int n, ret;
n = n_end - n_start;
if (n <= 0)
return 0;
ret = qcow_read(bs, start_sect + n_start, s->cluster_data, n);
if (ret < 0)
return ret;
if (s->crypt_method) {
encrypt_sectors(s, start_sect + n_start,
s->cluster_data,
s->cluster_data, n, 1,
&s->aes_encrypt_key);
}
ret = bdrv_write(s->hd, (cluster_offset >> 9) + n_start,
s->cluster_data, n);
if (ret < 0)
return ret;
return 0;
}
static void l2_cache_reset(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
memset(s->l2_cache, 0, s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
memset(s->l2_cache_offsets, 0, L2_CACHE_SIZE * sizeof(uint64_t));
memset(s->l2_cache_counts, 0, L2_CACHE_SIZE * sizeof(uint32_t));
}
static inline int l2_cache_new_entry(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
uint32_t min_count;
int min_index, i;
/* find a new entry in the least used one */
min_index = 0;
min_count = 0xffffffff;
for(i = 0; i < L2_CACHE_SIZE; i++) {
if (s->l2_cache_counts[i] < min_count) {
min_count = s->l2_cache_counts[i];
min_index = i;
}
}
return min_index;
}
static int64_t align_offset(int64_t offset, int n)
{
offset = (offset + n - 1) & ~(n - 1);
return offset;
}
static int grow_l1_table(BlockDriverState *bs, int min_size)
{
BDRVQcowState *s = bs->opaque;
int new_l1_size, new_l1_size2, ret, i;
uint64_t *new_l1_table;
uint64_t new_l1_table_offset;
uint8_t data[12];
new_l1_size = s->l1_size;
if (min_size <= new_l1_size)
return 0;
while (min_size > new_l1_size) {
new_l1_size = (new_l1_size * 3 + 1) / 2;
}
#ifdef DEBUG_ALLOC2
printf("grow l1_table from %d to %d\n", s->l1_size, new_l1_size);
#endif
new_l1_size2 = sizeof(uint64_t) * new_l1_size;
new_l1_table = qemu_mallocz(new_l1_size2);
memcpy(new_l1_table, s->l1_table, s->l1_size * sizeof(uint64_t));
/* write new table (align to cluster) */
new_l1_table_offset = alloc_clusters(bs, new_l1_size2);
for(i = 0; i < s->l1_size; i++)
new_l1_table[i] = cpu_to_be64(new_l1_table[i]);
ret = bdrv_pwrite(s->hd, new_l1_table_offset, new_l1_table, new_l1_size2);
if (ret != new_l1_size2)
goto fail;
for(i = 0; i < s->l1_size; i++)
new_l1_table[i] = be64_to_cpu(new_l1_table[i]);
/* set new table */
cpu_to_be32w((uint32_t*)data, new_l1_size);
cpu_to_be64w((uint64_t*)(data + 4), new_l1_table_offset);
if (bdrv_pwrite(s->hd, offsetof(QCowHeader, l1_size), data,
sizeof(data)) != sizeof(data))
goto fail;
qemu_free(s->l1_table);
free_clusters(bs, s->l1_table_offset, s->l1_size * sizeof(uint64_t));
s->l1_table_offset = new_l1_table_offset;
s->l1_table = new_l1_table;
s->l1_size = new_l1_size;
return 0;
fail:
qemu_free(s->l1_table);
return -EIO;
}
/*
* seek_l2_table
*
* seek l2_offset in the l2_cache table
* if not found, return NULL,
* if found,
* increments the l2 cache hit count of the entry,
* if counter overflow, divide by two all counters
* return the pointer to the l2 cache entry
*
*/
static uint64_t *seek_l2_table(BDRVQcowState *s, uint64_t l2_offset)
{
int i, j;
for(i = 0; i < L2_CACHE_SIZE; i++) {
if (l2_offset == s->l2_cache_offsets[i]) {
/* increment the hit count */
if (++s->l2_cache_counts[i] == 0xffffffff) {
for(j = 0; j < L2_CACHE_SIZE; j++) {
s->l2_cache_counts[j] >>= 1;
}
}
return s->l2_cache + (i << s->l2_bits);
}
}
return NULL;
}
/*
* l2_load
*
* Loads a L2 table into memory. If the table is in the cache, the cache
* is used; otherwise the L2 table is loaded from the image file.
*
* Returns a pointer to the L2 table on success, or NULL if the read from
* the image file failed.
*/
static uint64_t *l2_load(BlockDriverState *bs, uint64_t l2_offset)
{
BDRVQcowState *s = bs->opaque;
int min_index;
uint64_t *l2_table;
/* seek if the table for the given offset is in the cache */
l2_table = seek_l2_table(s, l2_offset);
if (l2_table != NULL)
return l2_table;
/* not found: load a new entry in the least used one */
min_index = l2_cache_new_entry(bs);
l2_table = s->l2_cache + (min_index << s->l2_bits);
if (bdrv_pread(s->hd, l2_offset, l2_table, s->l2_size * sizeof(uint64_t)) !=
s->l2_size * sizeof(uint64_t))
return NULL;
s->l2_cache_offsets[min_index] = l2_offset;
s->l2_cache_counts[min_index] = 1;
return l2_table;
}
/*
* l2_allocate
*
* Allocate a new l2 entry in the file. If l1_index points to an already
* used entry in the L2 table (i.e. we are doing a copy on write for the L2
* table) copy the contents of the old L2 table into the newly allocated one.
* Otherwise the new table is initialized with zeros.
*
*/
static uint64_t *l2_allocate(BlockDriverState *bs, int l1_index)
{
BDRVQcowState *s = bs->opaque;
int min_index;
uint64_t old_l2_offset, tmp;
uint64_t *l2_table, l2_offset;
old_l2_offset = s->l1_table[l1_index];
/* allocate a new l2 entry */
l2_offset = alloc_clusters(bs, s->l2_size * sizeof(uint64_t));
/* update the L1 entry */
s->l1_table[l1_index] = l2_offset | QCOW_OFLAG_COPIED;
tmp = cpu_to_be64(l2_offset | QCOW_OFLAG_COPIED);
if (bdrv_pwrite(s->hd, s->l1_table_offset + l1_index * sizeof(tmp),
&tmp, sizeof(tmp)) != sizeof(tmp))
return NULL;
/* allocate a new entry in the l2 cache */
min_index = l2_cache_new_entry(bs);
l2_table = s->l2_cache + (min_index << s->l2_bits);
if (old_l2_offset == 0) {
/* if there was no old l2 table, clear the new table */
memset(l2_table, 0, s->l2_size * sizeof(uint64_t));
} else {
/* if there was an old l2 table, read it from the disk */
if (bdrv_pread(s->hd, old_l2_offset,
l2_table, s->l2_size * sizeof(uint64_t)) !=
s->l2_size * sizeof(uint64_t))
return NULL;
}
/* write the l2 table to the file */
if (bdrv_pwrite(s->hd, l2_offset,
l2_table, s->l2_size * sizeof(uint64_t)) !=
s->l2_size * sizeof(uint64_t))
return NULL;
/* update the l2 cache entry */
s->l2_cache_offsets[min_index] = l2_offset;
s->l2_cache_counts[min_index] = 1;
return l2_table;
}
static int size_to_clusters(BDRVQcowState *s, int64_t size)
{
return (size + (s->cluster_size - 1)) >> s->cluster_bits;
}
static int count_contiguous_clusters(uint64_t nb_clusters, int cluster_size,
uint64_t *l2_table, uint64_t start, uint64_t mask)
{
int i;
uint64_t offset = be64_to_cpu(l2_table[0]) & ~mask;
if (!offset)
return 0;
for (i = start; i < start + nb_clusters; i++)
if (offset + i * cluster_size != (be64_to_cpu(l2_table[i]) & ~mask))
break;
return (i - start);
}
static int count_contiguous_free_clusters(uint64_t nb_clusters, uint64_t *l2_table)
{
int i = 0;
while(nb_clusters-- && l2_table[i] == 0)
i++;
return i;
}
/*
* get_cluster_offset
*
* For a given offset of the disk image, return cluster offset in
* qcow2 file.
*
* on entry, *num is the number of contiguous clusters we'd like to
* access following offset.
*
* on exit, *num is the number of contiguous clusters we can read.
*
* Return 1, if the offset is found
* Return 0, otherwise.
*
*/
static uint64_t get_cluster_offset(BlockDriverState *bs,
uint64_t offset, int *num)
{
BDRVQcowState *s = bs->opaque;
int l1_index, l2_index;
uint64_t l2_offset, *l2_table, cluster_offset;
int l1_bits, c;
int index_in_cluster, nb_available, nb_needed, nb_clusters;
index_in_cluster = (offset >> 9) & (s->cluster_sectors - 1);
nb_needed = *num + index_in_cluster;
l1_bits = s->l2_bits + s->cluster_bits;
/* compute how many bytes there are between the offset and
* the end of the l1 entry
*/
nb_available = (1 << l1_bits) - (offset & ((1 << l1_bits) - 1));
/* compute the number of available sectors */
nb_available = (nb_available >> 9) + index_in_cluster;
if (nb_needed > nb_available) {
nb_needed = nb_available;
}
cluster_offset = 0;
/* seek the the l2 offset in the l1 table */
l1_index = offset >> l1_bits;
if (l1_index >= s->l1_size)
goto out;
l2_offset = s->l1_table[l1_index];
/* seek the l2 table of the given l2 offset */
if (!l2_offset)
goto out;
/* load the l2 table in memory */
l2_offset &= ~QCOW_OFLAG_COPIED;
l2_table = l2_load(bs, l2_offset);
if (l2_table == NULL)
return 0;
/* find the cluster offset for the given disk offset */
l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
cluster_offset = be64_to_cpu(l2_table[l2_index]);
nb_clusters = size_to_clusters(s, nb_needed << 9);
if (!cluster_offset) {
/* how many empty clusters ? */
c = count_contiguous_free_clusters(nb_clusters, &l2_table[l2_index]);
} else {
/* how many allocated clusters ? */
c = count_contiguous_clusters(nb_clusters, s->cluster_size,
&l2_table[l2_index], 0, QCOW_OFLAG_COPIED);
}
nb_available = (c * s->cluster_sectors);
out:
if (nb_available > nb_needed)
nb_available = nb_needed;
*num = nb_available - index_in_cluster;
return cluster_offset & ~QCOW_OFLAG_COPIED;
}
/*
* free_any_clusters
*
* free clusters according to its type: compressed or not
*
*/
static void free_any_clusters(BlockDriverState *bs,
uint64_t cluster_offset, int nb_clusters)
{
BDRVQcowState *s = bs->opaque;
/* free the cluster */
if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
int nb_csectors;
nb_csectors = ((cluster_offset >> s->csize_shift) &
s->csize_mask) + 1;
free_clusters(bs, (cluster_offset & s->cluster_offset_mask) & ~511,
nb_csectors * 512);
return;
}
free_clusters(bs, cluster_offset, nb_clusters << s->cluster_bits);
return;
}
/*
* get_cluster_table
*
* for a given disk offset, load (and allocate if needed)
* the l2 table.
*
* the l2 table offset in the qcow2 file and the cluster index
* in the l2 table are given to the caller.
*
*/
static int get_cluster_table(BlockDriverState *bs, uint64_t offset,
uint64_t **new_l2_table,
uint64_t *new_l2_offset,
int *new_l2_index)
{
BDRVQcowState *s = bs->opaque;
int l1_index, l2_index, ret;
uint64_t l2_offset, *l2_table;
/* seek the the l2 offset in the l1 table */
l1_index = offset >> (s->l2_bits + s->cluster_bits);
if (l1_index >= s->l1_size) {
ret = grow_l1_table(bs, l1_index + 1);
if (ret < 0)
return 0;
}
l2_offset = s->l1_table[l1_index];
/* seek the l2 table of the given l2 offset */
if (l2_offset & QCOW_OFLAG_COPIED) {
/* load the l2 table in memory */
l2_offset &= ~QCOW_OFLAG_COPIED;
l2_table = l2_load(bs, l2_offset);
if (l2_table == NULL)
return 0;
} else {
if (l2_offset)
free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t));
l2_table = l2_allocate(bs, l1_index);
if (l2_table == NULL)
return 0;
l2_offset = s->l1_table[l1_index] & ~QCOW_OFLAG_COPIED;
}
/* find the cluster offset for the given disk offset */
l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
*new_l2_table = l2_table;
*new_l2_offset = l2_offset;
*new_l2_index = l2_index;
return 1;
}
/*
* alloc_compressed_cluster_offset
*
* For a given offset of the disk image, return cluster offset in
* qcow2 file.
*
* If the offset is not found, allocate a new compressed cluster.
*
* Return the cluster offset if successful,
* Return 0, otherwise.
*
*/
static uint64_t alloc_compressed_cluster_offset(BlockDriverState *bs,
uint64_t offset,
int compressed_size)
{
BDRVQcowState *s = bs->opaque;
int l2_index, ret;
uint64_t l2_offset, *l2_table, cluster_offset;
int nb_csectors;
ret = get_cluster_table(bs, offset, &l2_table, &l2_offset, &l2_index);
if (ret == 0)
return 0;
cluster_offset = be64_to_cpu(l2_table[l2_index]);
if (cluster_offset & QCOW_OFLAG_COPIED)
return cluster_offset & ~QCOW_OFLAG_COPIED;
if (cluster_offset)
free_any_clusters(bs, cluster_offset, 1);
cluster_offset = alloc_bytes(bs, compressed_size);
nb_csectors = ((cluster_offset + compressed_size - 1) >> 9) -
(cluster_offset >> 9);
cluster_offset |= QCOW_OFLAG_COMPRESSED |
((uint64_t)nb_csectors << s->csize_shift);
/* update L2 table */
/* compressed clusters never have the copied flag */
l2_table[l2_index] = cpu_to_be64(cluster_offset);
if (bdrv_pwrite(s->hd,
l2_offset + l2_index * sizeof(uint64_t),
l2_table + l2_index,
sizeof(uint64_t)) != sizeof(uint64_t))
return 0;
return cluster_offset;
}
typedef struct QCowL2Meta
{
uint64_t offset;
int n_start;
int nb_available;
int nb_clusters;
} QCowL2Meta;
static int alloc_cluster_link_l2(BlockDriverState *bs, uint64_t cluster_offset,
QCowL2Meta *m)
{
BDRVQcowState *s = bs->opaque;
int i, j = 0, l2_index, ret;
uint64_t *old_cluster, start_sect, l2_offset, *l2_table;
if (m->nb_clusters == 0)
return 0;
old_cluster = qemu_malloc(m->nb_clusters * sizeof(uint64_t));
/* copy content of unmodified sectors */
start_sect = (m->offset & ~(s->cluster_size - 1)) >> 9;
if (m->n_start) {
ret = copy_sectors(bs, start_sect, cluster_offset, 0, m->n_start);
if (ret < 0)
goto err;
}
if (m->nb_available & (s->cluster_sectors - 1)) {
uint64_t end = m->nb_available & ~(uint64_t)(s->cluster_sectors - 1);
ret = copy_sectors(bs, start_sect + end, cluster_offset + (end << 9),
m->nb_available - end, s->cluster_sectors);
if (ret < 0)
goto err;
}
ret = -EIO;
/* update L2 table */
if (!get_cluster_table(bs, m->offset, &l2_table, &l2_offset, &l2_index))
goto err;
for (i = 0; i < m->nb_clusters; i++) {
if(l2_table[l2_index + i] != 0)
old_cluster[j++] = l2_table[l2_index + i];
l2_table[l2_index + i] = cpu_to_be64((cluster_offset +
(i << s->cluster_bits)) | QCOW_OFLAG_COPIED);
}
if (bdrv_pwrite(s->hd, l2_offset + l2_index * sizeof(uint64_t),
l2_table + l2_index, m->nb_clusters * sizeof(uint64_t)) !=
m->nb_clusters * sizeof(uint64_t))
goto err;
for (i = 0; i < j; i++)
free_any_clusters(bs, old_cluster[i], 1);
ret = 0;
err:
qemu_free(old_cluster);
return ret;
}
/*
* alloc_cluster_offset
*
* For a given offset of the disk image, return cluster offset in
* qcow2 file.
*
* If the offset is not found, allocate a new cluster.
*
* Return the cluster offset if successful,
* Return 0, otherwise.
*
*/
static uint64_t alloc_cluster_offset(BlockDriverState *bs,
uint64_t offset,
int n_start, int n_end,
int *num, QCowL2Meta *m)
{
BDRVQcowState *s = bs->opaque;
int l2_index, ret;
uint64_t l2_offset, *l2_table, cluster_offset;
int nb_clusters, i = 0;
ret = get_cluster_table(bs, offset, &l2_table, &l2_offset, &l2_index);
if (ret == 0)
return 0;
nb_clusters = size_to_clusters(s, n_end << 9);
nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);
cluster_offset = be64_to_cpu(l2_table[l2_index]);
/* We keep all QCOW_OFLAG_COPIED clusters */
if (cluster_offset & QCOW_OFLAG_COPIED) {
nb_clusters = count_contiguous_clusters(nb_clusters, s->cluster_size,
&l2_table[l2_index], 0, 0);
cluster_offset &= ~QCOW_OFLAG_COPIED;
m->nb_clusters = 0;
goto out;
}
/* for the moment, multiple compressed clusters are not managed */
if (cluster_offset & QCOW_OFLAG_COMPRESSED)
nb_clusters = 1;
/* how many available clusters ? */
while (i < nb_clusters) {
i += count_contiguous_clusters(nb_clusters - i, s->cluster_size,
&l2_table[l2_index], i, 0);
if(be64_to_cpu(l2_table[l2_index + i]))
break;
i += count_contiguous_free_clusters(nb_clusters - i,
&l2_table[l2_index + i]);
cluster_offset = be64_to_cpu(l2_table[l2_index + i]);
if ((cluster_offset & QCOW_OFLAG_COPIED) ||
(cluster_offset & QCOW_OFLAG_COMPRESSED))
break;
}
nb_clusters = i;
/* allocate a new cluster */
cluster_offset = alloc_clusters(bs, nb_clusters * s->cluster_size);
/* save info needed for meta data update */
m->offset = offset;
m->n_start = n_start;
m->nb_clusters = nb_clusters;
out:
m->nb_available = MIN(nb_clusters << (s->cluster_bits - 9), n_end);
*num = m->nb_available - n_start;
return cluster_offset;
}
static int qcow_is_allocated(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, int *pnum)
{
uint64_t cluster_offset;
*pnum = nb_sectors;
cluster_offset = get_cluster_offset(bs, sector_num << 9, pnum);
return (cluster_offset != 0);
}
static int decompress_buffer(uint8_t *out_buf, int out_buf_size,
const uint8_t *buf, int buf_size)
{
z_stream strm1, *strm = &strm1;
int ret, out_len;
memset(strm, 0, sizeof(*strm));
strm->next_in = (uint8_t *)buf;
strm->avail_in = buf_size;
strm->next_out = out_buf;
strm->avail_out = out_buf_size;
ret = inflateInit2(strm, -12);
if (ret != Z_OK)
return -1;
ret = inflate(strm, Z_FINISH);
out_len = strm->next_out - out_buf;
if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) ||
out_len != out_buf_size) {
inflateEnd(strm);
return -1;
}
inflateEnd(strm);
return 0;
}
static int decompress_cluster(BDRVQcowState *s, uint64_t cluster_offset)
{
int ret, csize, nb_csectors, sector_offset;
uint64_t coffset;
coffset = cluster_offset & s->cluster_offset_mask;
if (s->cluster_cache_offset != coffset) {
nb_csectors = ((cluster_offset >> s->csize_shift) & s->csize_mask) + 1;
sector_offset = coffset & 511;
csize = nb_csectors * 512 - sector_offset;
ret = bdrv_read(s->hd, coffset >> 9, s->cluster_data, nb_csectors);
if (ret < 0) {
return -1;
}
if (decompress_buffer(s->cluster_cache, s->cluster_size,
s->cluster_data + sector_offset, csize) < 0) {
return -1;
}
s->cluster_cache_offset = coffset;
}
return 0;
}
/* handle reading after the end of the backing file */
static int backing_read1(BlockDriverState *bs,
int64_t sector_num, uint8_t *buf, int nb_sectors)
{
int n1;
if ((sector_num + nb_sectors) <= bs->total_sectors)
return nb_sectors;
if (sector_num >= bs->total_sectors)
n1 = 0;
else
n1 = bs->total_sectors - sector_num;
memset(buf + n1 * 512, 0, 512 * (nb_sectors - n1));
return n1;
}
static int qcow_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
{
BDRVQcowState *s = bs->opaque;
int ret, index_in_cluster, n, n1;
uint64_t cluster_offset;
while (nb_sectors > 0) {
n = nb_sectors;
cluster_offset = get_cluster_offset(bs, sector_num << 9, &n);
index_in_cluster = sector_num & (s->cluster_sectors - 1);
if (!cluster_offset) {
if (bs->backing_hd) {
/* read from the base image */
n1 = backing_read1(bs->backing_hd, sector_num, buf, n);
if (n1 > 0) {
ret = bdrv_read(bs->backing_hd, sector_num, buf, n1);
if (ret < 0)
return -1;
}
} else {
memset(buf, 0, 512 * n);
}
} else if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
if (decompress_cluster(s, cluster_offset) < 0)
return -1;
memcpy(buf, s->cluster_cache + index_in_cluster * 512, 512 * n);
} else {
ret = bdrv_pread(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512);
if (ret != n * 512)
return -1;
if (s->crypt_method) {
encrypt_sectors(s, sector_num, buf, buf, n, 0,
&s->aes_decrypt_key);
}
}
nb_sectors -= n;
sector_num += n;
buf += n * 512;
}
return 0;
}
static int qcow_write(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors)
{
BDRVQcowState *s = bs->opaque;
int ret, index_in_cluster, n;
uint64_t cluster_offset;
int n_end;
QCowL2Meta l2meta;
while (nb_sectors > 0) {
index_in_cluster = sector_num & (s->cluster_sectors - 1);
n_end = index_in_cluster + nb_sectors;
if (s->crypt_method &&
n_end > QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors)
n_end = QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors;
cluster_offset = alloc_cluster_offset(bs, sector_num << 9,
index_in_cluster,
n_end, &n, &l2meta);
if (!cluster_offset)
return -1;
if (s->crypt_method) {
encrypt_sectors(s, sector_num, s->cluster_data, buf, n, 1,
&s->aes_encrypt_key);
ret = bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512,
s->cluster_data, n * 512);
} else {
ret = bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512);
}
if (ret != n * 512 || alloc_cluster_link_l2(bs, cluster_offset, &l2meta) < 0) {
free_any_clusters(bs, cluster_offset, l2meta.nb_clusters);
return -1;
}
nb_sectors -= n;
sector_num += n;
buf += n * 512;
}
s->cluster_cache_offset = -1; /* disable compressed cache */
return 0;
}
typedef struct QCowAIOCB {
BlockDriverAIOCB common;
int64_t sector_num;
uint8_t *buf;
int nb_sectors;
int n;
uint64_t cluster_offset;
uint8_t *cluster_data;
BlockDriverAIOCB *hd_aiocb;
QEMUBH *bh;
QCowL2Meta l2meta;
} QCowAIOCB;
static void qcow_aio_read_cb(void *opaque, int ret);
static void qcow_aio_read_bh(void *opaque)
{
QCowAIOCB *acb = opaque;
qemu_bh_delete(acb->bh);
acb->bh = NULL;
qcow_aio_read_cb(opaque, 0);
}
static int qcow_schedule_bh(QEMUBHFunc *cb, QCowAIOCB *acb)
{
if (acb->bh)
return -EIO;
acb->bh = qemu_bh_new(cb, acb);
if (!acb->bh)
return -EIO;
qemu_bh_schedule(acb->bh);
return 0;
}
static void qcow_aio_read_cb(void *opaque, int ret)
{
QCowAIOCB *acb = opaque;
BlockDriverState *bs = acb->common.bs;
BDRVQcowState *s = bs->opaque;
int index_in_cluster, n1;
acb->hd_aiocb = NULL;
if (ret < 0) {
fail:
acb->common.cb(acb->common.opaque, ret);
qemu_aio_release(acb);
return;
}
/* post process the read buffer */
if (!acb->cluster_offset) {
/* nothing to do */
} else if (acb->cluster_offset & QCOW_OFLAG_COMPRESSED) {
/* nothing to do */
} else {
if (s->crypt_method) {
encrypt_sectors(s, acb->sector_num, acb->buf, acb->buf,
acb->n, 0,
&s->aes_decrypt_key);
}
}
acb->nb_sectors -= acb->n;
acb->sector_num += acb->n;
acb->buf += acb->n * 512;
if (acb->nb_sectors == 0) {
/* request completed */
acb->common.cb(acb->common.opaque, 0);
qemu_aio_release(acb);
return;
}
/* prepare next AIO request */
acb->n = acb->nb_sectors;
acb->cluster_offset = get_cluster_offset(bs, acb->sector_num << 9, &acb->n);
index_in_cluster = acb->sector_num & (s->cluster_sectors - 1);
if (!acb->cluster_offset) {
if (bs->backing_hd) {
/* read from the base image */
n1 = backing_read1(bs->backing_hd, acb->sector_num,
acb->buf, acb->n);
if (n1 > 0) {
acb->hd_aiocb = bdrv_aio_read(bs->backing_hd, acb->sector_num,
acb->buf, acb->n, qcow_aio_read_cb, acb);
if (acb->hd_aiocb == NULL)
goto fail;
} else {
ret = qcow_schedule_bh(qcow_aio_read_bh, acb);
if (ret < 0)
goto fail;
}
} else {
/* Note: in this case, no need to wait */
memset(acb->buf, 0, 512 * acb->n);
ret = qcow_schedule_bh(qcow_aio_read_bh, acb);
if (ret < 0)
goto fail;
}
} else if (acb->cluster_offset & QCOW_OFLAG_COMPRESSED) {
/* add AIO support for compressed blocks ? */
if (decompress_cluster(s, acb->cluster_offset) < 0)
goto fail;
memcpy(acb->buf,
s->cluster_cache + index_in_cluster * 512, 512 * acb->n);
ret = qcow_schedule_bh(qcow_aio_read_bh, acb);
if (ret < 0)
goto fail;
} else {
if ((acb->cluster_offset & 511) != 0) {
ret = -EIO;
goto fail;
}
acb->hd_aiocb = bdrv_aio_read(s->hd,
(acb->cluster_offset >> 9) + index_in_cluster,
acb->buf, acb->n, qcow_aio_read_cb, acb);
if (acb->hd_aiocb == NULL)
goto fail;
}
}
static QCowAIOCB *qcow_aio_setup(BlockDriverState *bs,
int64_t sector_num, uint8_t *buf, int nb_sectors,
BlockDriverCompletionFunc *cb, void *opaque)
{
QCowAIOCB *acb;
acb = qemu_aio_get(bs, cb, opaque);
if (!acb)
return NULL;
acb->hd_aiocb = NULL;
acb->sector_num = sector_num;
acb->buf = buf;
acb->nb_sectors = nb_sectors;
acb->n = 0;
acb->cluster_offset = 0;
acb->l2meta.nb_clusters = 0;
return acb;
}
static BlockDriverAIOCB *qcow_aio_read(BlockDriverState *bs,
int64_t sector_num, uint8_t *buf, int nb_sectors,
BlockDriverCompletionFunc *cb, void *opaque)
{
QCowAIOCB *acb;
acb = qcow_aio_setup(bs, sector_num, buf, nb_sectors, cb, opaque);
if (!acb)
return NULL;
qcow_aio_read_cb(acb, 0);
return &acb->common;
}
static void qcow_aio_write_cb(void *opaque, int ret)
{
QCowAIOCB *acb = opaque;
BlockDriverState *bs = acb->common.bs;
BDRVQcowState *s = bs->opaque;
int index_in_cluster;
const uint8_t *src_buf;
int n_end;
acb->hd_aiocb = NULL;
if (ret < 0) {
fail:
acb->common.cb(acb->common.opaque, ret);
qemu_aio_release(acb);
return;
}
if (alloc_cluster_link_l2(bs, acb->cluster_offset, &acb->l2meta) < 0) {
free_any_clusters(bs, acb->cluster_offset, acb->l2meta.nb_clusters);
goto fail;
}
acb->nb_sectors -= acb->n;
acb->sector_num += acb->n;
acb->buf += acb->n * 512;
if (acb->nb_sectors == 0) {
/* request completed */
acb->common.cb(acb->common.opaque, 0);
qemu_aio_release(acb);
return;
}
index_in_cluster = acb->sector_num & (s->cluster_sectors - 1);
n_end = index_in_cluster + acb->nb_sectors;
if (s->crypt_method &&
n_end > QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors)
n_end = QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors;
acb->cluster_offset = alloc_cluster_offset(bs, acb->sector_num << 9,
index_in_cluster,
n_end, &acb->n, &acb->l2meta);
if (!acb->cluster_offset || (acb->cluster_offset & 511) != 0) {
ret = -EIO;
goto fail;
}
if (s->crypt_method) {
if (!acb->cluster_data) {
acb->cluster_data = qemu_mallocz(QCOW_MAX_CRYPT_CLUSTERS *
s->cluster_size);
}
encrypt_sectors(s, acb->sector_num, acb->cluster_data, acb->buf,
acb->n, 1, &s->aes_encrypt_key);
src_buf = acb->cluster_data;
} else {
src_buf = acb->buf;
}
acb->hd_aiocb = bdrv_aio_write(s->hd,
(acb->cluster_offset >> 9) + index_in_cluster,
src_buf, acb->n,
qcow_aio_write_cb, acb);
if (acb->hd_aiocb == NULL)
goto fail;
}
static BlockDriverAIOCB *qcow_aio_write(BlockDriverState *bs,
int64_t sector_num, const uint8_t *buf, int nb_sectors,
BlockDriverCompletionFunc *cb, void *opaque)
{
BDRVQcowState *s = bs->opaque;
QCowAIOCB *acb;
s->cluster_cache_offset = -1; /* disable compressed cache */
acb = qcow_aio_setup(bs, sector_num, (uint8_t*)buf, nb_sectors, cb, opaque);
if (!acb)
return NULL;
qcow_aio_write_cb(acb, 0);
return &acb->common;
}
static void qcow_aio_cancel(BlockDriverAIOCB *blockacb)
{
QCowAIOCB *acb = (QCowAIOCB *)blockacb;
if (acb->hd_aiocb)
bdrv_aio_cancel(acb->hd_aiocb);
qemu_aio_release(acb);
}
static void qcow_close(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
qemu_free(s->l1_table);
qemu_free(s->l2_cache);
qemu_free(s->cluster_cache);
qemu_free(s->cluster_data);
refcount_close(bs);
bdrv_delete(s->hd);
}
/* XXX: use std qcow open function ? */
typedef struct QCowCreateState {
int cluster_size;
int cluster_bits;
uint16_t *refcount_block;
uint64_t *refcount_table;
int64_t l1_table_offset;
int64_t refcount_table_offset;
int64_t refcount_block_offset;
} QCowCreateState;
static void create_refcount_update(QCowCreateState *s,
int64_t offset, int64_t size)
{
int refcount;
int64_t start, last, cluster_offset;
uint16_t *p;
start = offset & ~(s->cluster_size - 1);
last = (offset + size - 1) & ~(s->cluster_size - 1);
for(cluster_offset = start; cluster_offset <= last;
cluster_offset += s->cluster_size) {
p = &s->refcount_block[cluster_offset >> s->cluster_bits];
refcount = be16_to_cpu(*p);
refcount++;
*p = cpu_to_be16(refcount);
}
}
static int qcow_create2(const char *filename, int64_t total_size,
const char *backing_file, const char *backing_format,
int flags)
{
int fd, header_size, backing_filename_len, l1_size, i, shift, l2_bits;
int ref_clusters, backing_format_len = 0;
QCowHeader header;
uint64_t tmp, offset;
QCowCreateState s1, *s = &s1;
QCowExtension ext_bf = {0, 0};
memset(s, 0, sizeof(*s));
fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644);
if (fd < 0)
return -1;
memset(&header, 0, sizeof(header));
header.magic = cpu_to_be32(QCOW_MAGIC);
header.version = cpu_to_be32(QCOW_VERSION);
header.size = cpu_to_be64(total_size * 512);
header_size = sizeof(header);
backing_filename_len = 0;
if (backing_file) {
if (backing_format) {
ext_bf.magic = QCOW_EXT_MAGIC_BACKING_FORMAT;
backing_format_len = strlen(backing_format);
ext_bf.len = (backing_format_len + 7) & ~7;
header_size += ((sizeof(ext_bf) + ext_bf.len + 7) & ~7);
}
header.backing_file_offset = cpu_to_be64(header_size);
backing_filename_len = strlen(backing_file);
header.backing_file_size = cpu_to_be32(backing_filename_len);
header_size += backing_filename_len;
}
s->cluster_bits = 12; /* 4 KB clusters */
s->cluster_size = 1 << s->cluster_bits;
header.cluster_bits = cpu_to_be32(s->cluster_bits);
header_size = (header_size + 7) & ~7;
if (flags & BLOCK_FLAG_ENCRYPT) {
header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
} else {
header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
}
l2_bits = s->cluster_bits - 3;
shift = s->cluster_bits + l2_bits;
l1_size = (((total_size * 512) + (1LL << shift) - 1) >> shift);
offset = align_offset(header_size, s->cluster_size);
s->l1_table_offset = offset;
header.l1_table_offset = cpu_to_be64(s->l1_table_offset);
header.l1_size = cpu_to_be32(l1_size);
offset += align_offset(l1_size * sizeof(uint64_t), s->cluster_size);
s->refcount_table = qemu_mallocz(s->cluster_size);
s->refcount_table_offset = offset;
header.refcount_table_offset = cpu_to_be64(offset);
header.refcount_table_clusters = cpu_to_be32(1);
offset += s->cluster_size;
s->refcount_block_offset = offset;
/* count how many refcount blocks needed */
tmp = offset >> s->cluster_bits;
ref_clusters = (tmp >> (s->cluster_bits - REFCOUNT_SHIFT)) + 1;
for (i=0; i < ref_clusters; i++) {
s->refcount_table[i] = cpu_to_be64(offset);
offset += s->cluster_size;
}
s->refcount_block = qemu_mallocz(ref_clusters * s->cluster_size);
/* update refcounts */
create_refcount_update(s, 0, header_size);
create_refcount_update(s, s->l1_table_offset, l1_size * sizeof(uint64_t));
create_refcount_update(s, s->refcount_table_offset, s->cluster_size);
create_refcount_update(s, s->refcount_block_offset, ref_clusters * s->cluster_size);
/* write all the data */
write(fd, &header, sizeof(header));
if (backing_file) {
if (backing_format_len) {
char zero[16];
int d = ext_bf.len - backing_format_len;
memset(zero, 0, sizeof(zero));
cpu_to_be32s(&ext_bf.magic);
cpu_to_be32s(&ext_bf.len);
write(fd, &ext_bf, sizeof(ext_bf));
write(fd, backing_format, backing_format_len);
if (d>0) {
write(fd, zero, d);
}
}
write(fd, backing_file, backing_filename_len);
}
lseek(fd, s->l1_table_offset, SEEK_SET);
tmp = 0;
for(i = 0;i < l1_size; i++) {
write(fd, &tmp, sizeof(tmp));
}
lseek(fd, s->refcount_table_offset, SEEK_SET);
write(fd, s->refcount_table, s->cluster_size);
lseek(fd, s->refcount_block_offset, SEEK_SET);
write(fd, s->refcount_block, ref_clusters * s->cluster_size);
qemu_free(s->refcount_table);
qemu_free(s->refcount_block);
close(fd);
return 0;
}
static int qcow_create(const char *filename, int64_t total_size,
const char *backing_file, int flags)
{
return qcow_create2(filename, total_size, backing_file, NULL, flags);
}
static int qcow_make_empty(BlockDriverState *bs)
{
#if 0
/* XXX: not correct */
BDRVQcowState *s = bs->opaque;
uint32_t l1_length = s->l1_size * sizeof(uint64_t);
int ret;
memset(s->l1_table, 0, l1_length);
if (bdrv_pwrite(s->hd, s->l1_table_offset, s->l1_table, l1_length) < 0)
return -1;
ret = bdrv_truncate(s->hd, s->l1_table_offset + l1_length);
if (ret < 0)
return ret;
l2_cache_reset(bs);
#endif
return 0;
}
/* XXX: put compressed sectors first, then all the cluster aligned
tables to avoid losing bytes in alignment */
static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors)
{
BDRVQcowState *s = bs->opaque;
z_stream strm;
int ret, out_len;
uint8_t *out_buf;
uint64_t cluster_offset;
if (nb_sectors == 0) {
/* align end of file to a sector boundary to ease reading with
sector based I/Os */
cluster_offset = bdrv_getlength(s->hd);
cluster_offset = (cluster_offset + 511) & ~511;
bdrv_truncate(s->hd, cluster_offset);
return 0;
}
if (nb_sectors != s->cluster_sectors)
return -EINVAL;
out_buf = qemu_malloc(s->cluster_size + (s->cluster_size / 1000) + 128);
/* best compression, small window, no zlib header */
memset(&strm, 0, sizeof(strm));
ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION,
Z_DEFLATED, -12,
9, Z_DEFAULT_STRATEGY);
if (ret != 0) {
qemu_free(out_buf);
return -1;
}
strm.avail_in = s->cluster_size;
strm.next_in = (uint8_t *)buf;
strm.avail_out = s->cluster_size;
strm.next_out = out_buf;
ret = deflate(&strm, Z_FINISH);
if (ret != Z_STREAM_END && ret != Z_OK) {
qemu_free(out_buf);
deflateEnd(&strm);
return -1;
}
out_len = strm.next_out - out_buf;
deflateEnd(&strm);
if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
/* could not compress: write normal cluster */
qcow_write(bs, sector_num, buf, s->cluster_sectors);
} else {
cluster_offset = alloc_compressed_cluster_offset(bs, sector_num << 9,
out_len);
if (!cluster_offset)
return -1;
cluster_offset &= s->cluster_offset_mask;
if (bdrv_pwrite(s->hd, cluster_offset, out_buf, out_len) != out_len) {
qemu_free(out_buf);
return -1;
}
}
qemu_free(out_buf);
return 0;
}
static void qcow_flush(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
bdrv_flush(s->hd);
}
static int qcow_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
{
BDRVQcowState *s = bs->opaque;
bdi->cluster_size = s->cluster_size;
bdi->vm_state_offset = (int64_t)s->l1_vm_state_index <<
(s->cluster_bits + s->l2_bits);
return 0;
}
/*********************************************************/
/* snapshot support */
/* update the refcounts of snapshots and the copied flag */
static int update_snapshot_refcount(BlockDriverState *bs,
int64_t l1_table_offset,
int l1_size,
int addend)
{
BDRVQcowState *s = bs->opaque;
uint64_t *l1_table, *l2_table, l2_offset, offset, l1_size2, l1_allocated;
int64_t old_offset, old_l2_offset;
int l2_size, i, j, l1_modified, l2_modified, nb_csectors, refcount;
l2_cache_reset(bs);
l2_table = NULL;
l1_table = NULL;
l1_size2 = l1_size * sizeof(uint64_t);
l1_allocated = 0;
if (l1_table_offset != s->l1_table_offset) {
l1_table = qemu_malloc(l1_size2);
l1_allocated = 1;
if (bdrv_pread(s->hd, l1_table_offset,
l1_table, l1_size2) != l1_size2)
goto fail;
for(i = 0;i < l1_size; i++)
be64_to_cpus(&l1_table[i]);
} else {
assert(l1_size == s->l1_size);
l1_table = s->l1_table;
l1_allocated = 0;
}
l2_size = s->l2_size * sizeof(uint64_t);
l2_table = qemu_malloc(l2_size);
l1_modified = 0;
for(i = 0; i < l1_size; i++) {
l2_offset = l1_table[i];
if (l2_offset) {
old_l2_offset = l2_offset;
l2_offset &= ~QCOW_OFLAG_COPIED;
l2_modified = 0;
if (bdrv_pread(s->hd, l2_offset, l2_table, l2_size) != l2_size)
goto fail;
for(j = 0; j < s->l2_size; j++) {
offset = be64_to_cpu(l2_table[j]);
if (offset != 0) {
old_offset = offset;
offset &= ~QCOW_OFLAG_COPIED;
if (offset & QCOW_OFLAG_COMPRESSED) {
nb_csectors = ((offset >> s->csize_shift) &
s->csize_mask) + 1;
if (addend != 0)
update_refcount(bs, (offset & s->cluster_offset_mask) & ~511,
nb_csectors * 512, addend);
/* compressed clusters are never modified */
refcount = 2;
} else {
if (addend != 0) {
refcount = update_cluster_refcount(bs, offset >> s->cluster_bits, addend);
} else {
refcount = get_refcount(bs, offset >> s->cluster_bits);
}
}
if (refcount == 1) {
offset |= QCOW_OFLAG_COPIED;
}
if (offset != old_offset) {
l2_table[j] = cpu_to_be64(offset);
l2_modified = 1;
}
}
}
if (l2_modified) {
if (bdrv_pwrite(s->hd,
l2_offset, l2_table, l2_size) != l2_size)
goto fail;
}
if (addend != 0) {
refcount = update_cluster_refcount(bs, l2_offset >> s->cluster_bits, addend);
} else {
refcount = get_refcount(bs, l2_offset >> s->cluster_bits);
}
if (refcount == 1) {
l2_offset |= QCOW_OFLAG_COPIED;
}
if (l2_offset != old_l2_offset) {
l1_table[i] = l2_offset;
l1_modified = 1;
}
}
}
if (l1_modified) {
for(i = 0; i < l1_size; i++)
cpu_to_be64s(&l1_table[i]);
if (bdrv_pwrite(s->hd, l1_table_offset, l1_table,
l1_size2) != l1_size2)
goto fail;
for(i = 0; i < l1_size; i++)
be64_to_cpus(&l1_table[i]);
}
if (l1_allocated)
qemu_free(l1_table);
qemu_free(l2_table);
return 0;
fail:
if (l1_allocated)
qemu_free(l1_table);
qemu_free(l2_table);
return -EIO;
}
static void qcow_free_snapshots(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
int i;
for(i = 0; i < s->nb_snapshots; i++) {
qemu_free(s->snapshots[i].name);
qemu_free(s->snapshots[i].id_str);
}
qemu_free(s->snapshots);
s->snapshots = NULL;
s->nb_snapshots = 0;
}
static int qcow_read_snapshots(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
QCowSnapshotHeader h;
QCowSnapshot *sn;
int i, id_str_size, name_size;
int64_t offset;
uint32_t extra_data_size;
if (!s->nb_snapshots) {
s->snapshots = NULL;
s->snapshots_size = 0;
return 0;
}
offset = s->snapshots_offset;
s->snapshots = qemu_mallocz(s->nb_snapshots * sizeof(QCowSnapshot));
for(i = 0; i < s->nb_snapshots; i++) {
offset = align_offset(offset, 8);
if (bdrv_pread(s->hd, offset, &h, sizeof(h)) != sizeof(h))
goto fail;
offset += sizeof(h);
sn = s->snapshots + i;
sn->l1_table_offset = be64_to_cpu(h.l1_table_offset);
sn->l1_size = be32_to_cpu(h.l1_size);
sn->vm_state_size = be32_to_cpu(h.vm_state_size);
sn->date_sec = be32_to_cpu(h.date_sec);
sn->date_nsec = be32_to_cpu(h.date_nsec);
sn->vm_clock_nsec = be64_to_cpu(h.vm_clock_nsec);
extra_data_size = be32_to_cpu(h.extra_data_size);
id_str_size = be16_to_cpu(h.id_str_size);
name_size = be16_to_cpu(h.name_size);
offset += extra_data_size;
sn->id_str = qemu_malloc(id_str_size + 1);
if (bdrv_pread(s->hd, offset, sn->id_str, id_str_size) != id_str_size)
goto fail;
offset += id_str_size;
sn->id_str[id_str_size] = '\0';
sn->name = qemu_malloc(name_size + 1);
if (bdrv_pread(s->hd, offset, sn->name, name_size) != name_size)
goto fail;
offset += name_size;
sn->name[name_size] = '\0';
}
s->snapshots_size = offset - s->snapshots_offset;
return 0;
fail:
qcow_free_snapshots(bs);
return -1;
}
/* add at the end of the file a new list of snapshots */
static int qcow_write_snapshots(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
QCowSnapshot *sn;
QCowSnapshotHeader h;
int i, name_size, id_str_size, snapshots_size;
uint64_t data64;
uint32_t data32;
int64_t offset, snapshots_offset;
/* compute the size of the snapshots */
offset = 0;
for(i = 0; i < s->nb_snapshots; i++) {
sn = s->snapshots + i;
offset = align_offset(offset, 8);
offset += sizeof(h);
offset += strlen(sn->id_str);
offset += strlen(sn->name);
}
snapshots_size = offset;
snapshots_offset = alloc_clusters(bs, snapshots_size);
offset = snapshots_offset;
for(i = 0; i < s->nb_snapshots; i++) {
sn = s->snapshots + i;
memset(&h, 0, sizeof(h));
h.l1_table_offset = cpu_to_be64(sn->l1_table_offset);
h.l1_size = cpu_to_be32(sn->l1_size);
h.vm_state_size = cpu_to_be32(sn->vm_state_size);
h.date_sec = cpu_to_be32(sn->date_sec);
h.date_nsec = cpu_to_be32(sn->date_nsec);
h.vm_clock_nsec = cpu_to_be64(sn->vm_clock_nsec);
id_str_size = strlen(sn->id_str);
name_size = strlen(sn->name);
h.id_str_size = cpu_to_be16(id_str_size);
h.name_size = cpu_to_be16(name_size);
offset = align_offset(offset, 8);
if (bdrv_pwrite(s->hd, offset, &h, sizeof(h)) != sizeof(h))
goto fail;
offset += sizeof(h);
if (bdrv_pwrite(s->hd, offset, sn->id_str, id_str_size) != id_str_size)
goto fail;
offset += id_str_size;
if (bdrv_pwrite(s->hd, offset, sn->name, name_size) != name_size)
goto fail;
offset += name_size;
}
/* update the various header fields */
data64 = cpu_to_be64(snapshots_offset);
if (bdrv_pwrite(s->hd, offsetof(QCowHeader, snapshots_offset),
&data64, sizeof(data64)) != sizeof(data64))
goto fail;
data32 = cpu_to_be32(s->nb_snapshots);
if (bdrv_pwrite(s->hd, offsetof(QCowHeader, nb_snapshots),
&data32, sizeof(data32)) != sizeof(data32))
goto fail;
/* free the old snapshot table */
free_clusters(bs, s->snapshots_offset, s->snapshots_size);
s->snapshots_offset = snapshots_offset;
s->snapshots_size = snapshots_size;
return 0;
fail:
return -1;
}
static void find_new_snapshot_id(BlockDriverState *bs,
char *id_str, int id_str_size)
{
BDRVQcowState *s = bs->opaque;
QCowSnapshot *sn;
int i, id, id_max = 0;
for(i = 0; i < s->nb_snapshots; i++) {
sn = s->snapshots + i;
id = strtoul(sn->id_str, NULL, 10);
if (id > id_max)
id_max = id;
}
snprintf(id_str, id_str_size, "%d", id_max + 1);
}
static int find_snapshot_by_id(BlockDriverState *bs, const char *id_str)
{
BDRVQcowState *s = bs->opaque;
int i;
for(i = 0; i < s->nb_snapshots; i++) {
if (!strcmp(s->snapshots[i].id_str, id_str))
return i;
}
return -1;
}
static int find_snapshot_by_id_or_name(BlockDriverState *bs, const char *name)
{
BDRVQcowState *s = bs->opaque;
int i, ret;
ret = find_snapshot_by_id(bs, name);
if (ret >= 0)
return ret;
for(i = 0; i < s->nb_snapshots; i++) {
if (!strcmp(s->snapshots[i].name, name))
return i;
}
return -1;
}
/* if no id is provided, a new one is constructed */
static int qcow_snapshot_create(BlockDriverState *bs,
QEMUSnapshotInfo *sn_info)
{
BDRVQcowState *s = bs->opaque;
QCowSnapshot *snapshots1, sn1, *sn = &sn1;
int i, ret;
uint64_t *l1_table = NULL;
memset(sn, 0, sizeof(*sn));
if (sn_info->id_str[0] == '\0') {
/* compute a new id */
find_new_snapshot_id(bs, sn_info->id_str, sizeof(sn_info->id_str));
}
/* check that the ID is unique */
if (find_snapshot_by_id(bs, sn_info->id_str) >= 0)
return -ENOENT;
sn->id_str = qemu_strdup(sn_info->id_str);
if (!sn->id_str)
goto fail;
sn->name = qemu_strdup(sn_info->name);
if (!sn->name)
goto fail;
sn->vm_state_size = sn_info->vm_state_size;
sn->date_sec = sn_info->date_sec;
sn->date_nsec = sn_info->date_nsec;
sn->vm_clock_nsec = sn_info->vm_clock_nsec;
ret = update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1);
if (ret < 0)
goto fail;
/* create the L1 table of the snapshot */
sn->l1_table_offset = alloc_clusters(bs, s->l1_size * sizeof(uint64_t));
sn->l1_size = s->l1_size;
l1_table = qemu_malloc(s->l1_size * sizeof(uint64_t));
for(i = 0; i < s->l1_size; i++) {
l1_table[i] = cpu_to_be64(s->l1_table[i]);
}
if (bdrv_pwrite(s->hd, sn->l1_table_offset,
l1_table, s->l1_size * sizeof(uint64_t)) !=
(s->l1_size * sizeof(uint64_t)))
goto fail;
qemu_free(l1_table);
l1_table = NULL;
snapshots1 = qemu_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot));
if (s->snapshots) {
memcpy(snapshots1, s->snapshots, s->nb_snapshots * sizeof(QCowSnapshot));
qemu_free(s->snapshots);
}
s->snapshots = snapshots1;
s->snapshots[s->nb_snapshots++] = *sn;
if (qcow_write_snapshots(bs) < 0)
goto fail;
#ifdef DEBUG_ALLOC
check_refcounts(bs);
#endif
return 0;
fail:
qemu_free(sn->name);
qemu_free(l1_table);
return -1;
}
/* copy the snapshot 'snapshot_name' into the current disk image */
static int qcow_snapshot_goto(BlockDriverState *bs,
const char *snapshot_id)
{
BDRVQcowState *s = bs->opaque;
QCowSnapshot *sn;
int i, snapshot_index, l1_size2;
snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
if (snapshot_index < 0)
return -ENOENT;
sn = &s->snapshots[snapshot_index];
if (update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, -1) < 0)
goto fail;
if (grow_l1_table(bs, sn->l1_size) < 0)
goto fail;
s->l1_size = sn->l1_size;
l1_size2 = s->l1_size * sizeof(uint64_t);
/* copy the snapshot l1 table to the current l1 table */
if (bdrv_pread(s->hd, sn->l1_table_offset,
s->l1_table, l1_size2) != l1_size2)
goto fail;
if (bdrv_pwrite(s->hd, s->l1_table_offset,
s->l1_table, l1_size2) != l1_size2)
goto fail;
for(i = 0;i < s->l1_size; i++) {
be64_to_cpus(&s->l1_table[i]);
}
if (update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1) < 0)
goto fail;
#ifdef DEBUG_ALLOC
check_refcounts(bs);
#endif
return 0;
fail:
return -EIO;
}
static int qcow_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
{
BDRVQcowState *s = bs->opaque;
QCowSnapshot *sn;
int snapshot_index, ret;
snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
if (snapshot_index < 0)
return -ENOENT;
sn = &s->snapshots[snapshot_index];
ret = update_snapshot_refcount(bs, sn->l1_table_offset, sn->l1_size, -1);
if (ret < 0)
return ret;
/* must update the copied flag on the current cluster offsets */
ret = update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0);
if (ret < 0)
return ret;
free_clusters(bs, sn->l1_table_offset, sn->l1_size * sizeof(uint64_t));
qemu_free(sn->id_str);
qemu_free(sn->name);
memmove(sn, sn + 1, (s->nb_snapshots - snapshot_index - 1) * sizeof(*sn));
s->nb_snapshots--;
ret = qcow_write_snapshots(bs);
if (ret < 0) {
/* XXX: restore snapshot if error ? */
return ret;
}
#ifdef DEBUG_ALLOC
check_refcounts(bs);
#endif
return 0;
}
static int qcow_snapshot_list(BlockDriverState *bs,
QEMUSnapshotInfo **psn_tab)
{
BDRVQcowState *s = bs->opaque;
QEMUSnapshotInfo *sn_tab, *sn_info;
QCowSnapshot *sn;
int i;
sn_tab = qemu_mallocz(s->nb_snapshots * sizeof(QEMUSnapshotInfo));
for(i = 0; i < s->nb_snapshots; i++) {
sn_info = sn_tab + i;
sn = s->snapshots + i;
pstrcpy(sn_info->id_str, sizeof(sn_info->id_str),
sn->id_str);
pstrcpy(sn_info->name, sizeof(sn_info->name),
sn->name);
sn_info->vm_state_size = sn->vm_state_size;
sn_info->date_sec = sn->date_sec;
sn_info->date_nsec = sn->date_nsec;
sn_info->vm_clock_nsec = sn->vm_clock_nsec;
}
*psn_tab = sn_tab;
return s->nb_snapshots;
}
/*********************************************************/
/* refcount handling */
static int refcount_init(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
int ret, refcount_table_size2, i;
s->refcount_block_cache = qemu_malloc(s->cluster_size);
refcount_table_size2 = s->refcount_table_size * sizeof(uint64_t);
s->refcount_table = qemu_malloc(refcount_table_size2);
if (s->refcount_table_size > 0) {
ret = bdrv_pread(s->hd, s->refcount_table_offset,
s->refcount_table, refcount_table_size2);
if (ret != refcount_table_size2)
goto fail;
for(i = 0; i < s->refcount_table_size; i++)
be64_to_cpus(&s->refcount_table[i]);
}
return 0;
fail:
return -ENOMEM;
}
static void refcount_close(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
qemu_free(s->refcount_block_cache);
qemu_free(s->refcount_table);
}
static int load_refcount_block(BlockDriverState *bs,
int64_t refcount_block_offset)
{
BDRVQcowState *s = bs->opaque;
int ret;
ret = bdrv_pread(s->hd, refcount_block_offset, s->refcount_block_cache,
s->cluster_size);
if (ret != s->cluster_size)
return -EIO;
s->refcount_block_cache_offset = refcount_block_offset;
return 0;
}
static int get_refcount(BlockDriverState *bs, int64_t cluster_index)
{
BDRVQcowState *s = bs->opaque;
int refcount_table_index, block_index;
int64_t refcount_block_offset;
refcount_table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT);
if (refcount_table_index >= s->refcount_table_size)
return 0;
refcount_block_offset = s->refcount_table[refcount_table_index];
if (!refcount_block_offset)
return 0;
if (refcount_block_offset != s->refcount_block_cache_offset) {
/* better than nothing: return allocated if read error */
if (load_refcount_block(bs, refcount_block_offset) < 0)
return 1;
}
block_index = cluster_index &
((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1);
return be16_to_cpu(s->refcount_block_cache[block_index]);
}
/* return < 0 if error */
static int64_t alloc_clusters_noref(BlockDriverState *bs, int64_t size)
{
BDRVQcowState *s = bs->opaque;
int i, nb_clusters;
nb_clusters = size_to_clusters(s, size);
retry:
for(i = 0; i < nb_clusters; i++) {
int64_t i = s->free_cluster_index++;
if (get_refcount(bs, i) != 0)
goto retry;
}
#ifdef DEBUG_ALLOC2
printf("alloc_clusters: size=%lld -> %lld\n",
size,
(s->free_cluster_index - nb_clusters) << s->cluster_bits);
#endif
return (s->free_cluster_index - nb_clusters) << s->cluster_bits;
}
static int64_t alloc_clusters(BlockDriverState *bs, int64_t size)
{
int64_t offset;
offset = alloc_clusters_noref(bs, size);
update_refcount(bs, offset, size, 1);
return offset;
}
/* only used to allocate compressed sectors. We try to allocate
contiguous sectors. size must be <= cluster_size */
static int64_t alloc_bytes(BlockDriverState *bs, int size)
{
BDRVQcowState *s = bs->opaque;
int64_t offset, cluster_offset;
int free_in_cluster;
assert(size > 0 && size <= s->cluster_size);
if (s->free_byte_offset == 0) {
s->free_byte_offset = alloc_clusters(bs, s->cluster_size);
}
redo:
free_in_cluster = s->cluster_size -
(s->free_byte_offset & (s->cluster_size - 1));
if (size <= free_in_cluster) {
/* enough space in current cluster */
offset = s->free_byte_offset;
s->free_byte_offset += size;
free_in_cluster -= size;
if (free_in_cluster == 0)
s->free_byte_offset = 0;
if ((offset & (s->cluster_size - 1)) != 0)
update_cluster_refcount(bs, offset >> s->cluster_bits, 1);
} else {
offset = alloc_clusters(bs, s->cluster_size);
cluster_offset = s->free_byte_offset & ~(s->cluster_size - 1);
if ((cluster_offset + s->cluster_size) == offset) {
/* we are lucky: contiguous data */
offset = s->free_byte_offset;
update_cluster_refcount(bs, offset >> s->cluster_bits, 1);
s->free_byte_offset += size;
} else {
s->free_byte_offset = offset;
goto redo;
}
}
return offset;
}
static void free_clusters(BlockDriverState *bs,
int64_t offset, int64_t size)
{
update_refcount(bs, offset, size, -1);
}
static int grow_refcount_table(BlockDriverState *bs, int min_size)
{
BDRVQcowState *s = bs->opaque;
int new_table_size, new_table_size2, refcount_table_clusters, i, ret;
uint64_t *new_table;
int64_t table_offset;
uint8_t data[12];
int old_table_size;
int64_t old_table_offset;
if (min_size <= s->refcount_table_size)
return 0;
/* compute new table size */
refcount_table_clusters = s->refcount_table_size >> (s->cluster_bits - 3);
for(;;) {
if (refcount_table_clusters == 0) {
refcount_table_clusters = 1;
} else {
refcount_table_clusters = (refcount_table_clusters * 3 + 1) / 2;
}
new_table_size = refcount_table_clusters << (s->cluster_bits - 3);
if (min_size <= new_table_size)
break;
}
#ifdef DEBUG_ALLOC2
printf("grow_refcount_table from %d to %d\n",
s->refcount_table_size,
new_table_size);
#endif
new_table_size2 = new_table_size * sizeof(uint64_t);
new_table = qemu_mallocz(new_table_size2);
memcpy(new_table, s->refcount_table,
s->refcount_table_size * sizeof(uint64_t));
for(i = 0; i < s->refcount_table_size; i++)
cpu_to_be64s(&new_table[i]);
/* Note: we cannot update the refcount now to avoid recursion */
table_offset = alloc_clusters_noref(bs, new_table_size2);
ret = bdrv_pwrite(s->hd, table_offset, new_table, new_table_size2);
if (ret != new_table_size2)
goto fail;
for(i = 0; i < s->refcount_table_size; i++)
be64_to_cpus(&new_table[i]);
cpu_to_be64w((uint64_t*)data, table_offset);
cpu_to_be32w((uint32_t*)(data + 8), refcount_table_clusters);
if (bdrv_pwrite(s->hd, offsetof(QCowHeader, refcount_table_offset),
data, sizeof(data)) != sizeof(data))
goto fail;
qemu_free(s->refcount_table);
old_table_offset = s->refcount_table_offset;
old_table_size = s->refcount_table_size;
s->refcount_table = new_table;
s->refcount_table_size = new_table_size;
s->refcount_table_offset = table_offset;
update_refcount(bs, table_offset, new_table_size2, 1);
free_clusters(bs, old_table_offset, old_table_size * sizeof(uint64_t));
return 0;
fail:
free_clusters(bs, table_offset, new_table_size2);
qemu_free(new_table);
return -EIO;
}
/* addend must be 1 or -1 */
/* XXX: cache several refcount block clusters ? */
static int update_cluster_refcount(BlockDriverState *bs,
int64_t cluster_index,
int addend)
{
BDRVQcowState *s = bs->opaque;
int64_t offset, refcount_block_offset;
int ret, refcount_table_index, block_index, refcount;
uint64_t data64;
refcount_table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT);
if (refcount_table_index >= s->refcount_table_size) {
if (addend < 0)
return -EINVAL;
ret = grow_refcount_table(bs, refcount_table_index + 1);
if (ret < 0)
return ret;
}
refcount_block_offset = s->refcount_table[refcount_table_index];
if (!refcount_block_offset) {
if (addend < 0)
return -EINVAL;
/* create a new refcount block */
/* Note: we cannot update the refcount now to avoid recursion */
offset = alloc_clusters_noref(bs, s->cluster_size);
memset(s->refcount_block_cache, 0, s->cluster_size);
ret = bdrv_pwrite(s->hd, offset, s->refcount_block_cache, s->cluster_size);
if (ret != s->cluster_size)
return -EINVAL;
s->refcount_table[refcount_table_index] = offset;
data64 = cpu_to_be64(offset);
ret = bdrv_pwrite(s->hd, s->refcount_table_offset +
refcount_table_index * sizeof(uint64_t),
&data64, sizeof(data64));
if (ret != sizeof(data64))
return -EINVAL;
refcount_block_offset = offset;
s->refcount_block_cache_offset = offset;
update_refcount(bs, offset, s->cluster_size, 1);
} else {
if (refcount_block_offset != s->refcount_block_cache_offset) {
if (load_refcount_block(bs, refcount_block_offset) < 0)
return -EIO;
}
}
/* we can update the count and save it */
block_index = cluster_index &
((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1);
refcount = be16_to_cpu(s->refcount_block_cache[block_index]);
refcount += addend;
if (refcount < 0 || refcount > 0xffff)
return -EINVAL;
if (refcount == 0 && cluster_index < s->free_cluster_index) {
s->free_cluster_index = cluster_index;
}
s->refcount_block_cache[block_index] = cpu_to_be16(refcount);
if (bdrv_pwrite(s->hd,
refcount_block_offset + (block_index << REFCOUNT_SHIFT),
&s->refcount_block_cache[block_index], 2) != 2)
return -EIO;
return refcount;
}
static void update_refcount(BlockDriverState *bs,
int64_t offset, int64_t length,
int addend)
{
BDRVQcowState *s = bs->opaque;
int64_t start, last, cluster_offset;
#ifdef DEBUG_ALLOC2
printf("update_refcount: offset=%lld size=%lld addend=%d\n",
offset, length, addend);
#endif
if (length <= 0)
return;
start = offset & ~(s->cluster_size - 1);
last = (offset + length - 1) & ~(s->cluster_size - 1);
for(cluster_offset = start; cluster_offset <= last;
cluster_offset += s->cluster_size) {
update_cluster_refcount(bs, cluster_offset >> s->cluster_bits, addend);
}
}
#ifdef DEBUG_ALLOC
static void inc_refcounts(BlockDriverState *bs,
uint16_t *refcount_table,
int refcount_table_size,
int64_t offset, int64_t size)
{
BDRVQcowState *s = bs->opaque;
int64_t start, last, cluster_offset;
int k;
if (size <= 0)
return;
start = offset & ~(s->cluster_size - 1);
last = (offset + size - 1) & ~(s->cluster_size - 1);
for(cluster_offset = start; cluster_offset <= last;
cluster_offset += s->cluster_size) {
k = cluster_offset >> s->cluster_bits;
if (k < 0 || k >= refcount_table_size) {
printf("ERROR: invalid cluster offset=0x%llx\n", cluster_offset);
} else {
if (++refcount_table[k] == 0) {
printf("ERROR: overflow cluster offset=0x%llx\n", cluster_offset);
}
}
}
}
static int check_refcounts_l1(BlockDriverState *bs,
uint16_t *refcount_table,
int refcount_table_size,
int64_t l1_table_offset, int l1_size,
int check_copied)
{
BDRVQcowState *s = bs->opaque;
uint64_t *l1_table, *l2_table, l2_offset, offset, l1_size2;
int l2_size, i, j, nb_csectors, refcount;
l2_table = NULL;
l1_size2 = l1_size * sizeof(uint64_t);
inc_refcounts(bs, refcount_table, refcount_table_size,
l1_table_offset, l1_size2);
l1_table = qemu_malloc(l1_size2);
if (bdrv_pread(s->hd, l1_table_offset,
l1_table, l1_size2) != l1_size2)
goto fail;
for(i = 0;i < l1_size; i++)
be64_to_cpus(&l1_table[i]);
l2_size = s->l2_size * sizeof(uint64_t);
l2_table = qemu_malloc(l2_size);
for(i = 0; i < l1_size; i++) {
l2_offset = l1_table[i];
if (l2_offset) {
if (check_copied) {
refcount = get_refcount(bs, (l2_offset & ~QCOW_OFLAG_COPIED) >> s->cluster_bits);
if ((refcount == 1) != ((l2_offset & QCOW_OFLAG_COPIED) != 0)) {
printf("ERROR OFLAG_COPIED: l2_offset=%llx refcount=%d\n",
l2_offset, refcount);
}
}
l2_offset &= ~QCOW_OFLAG_COPIED;
if (bdrv_pread(s->hd, l2_offset, l2_table, l2_size) != l2_size)
goto fail;
for(j = 0; j < s->l2_size; j++) {
offset = be64_to_cpu(l2_table[j]);
if (offset != 0) {
if (offset & QCOW_OFLAG_COMPRESSED) {
if (offset & QCOW_OFLAG_COPIED) {
printf("ERROR: cluster %lld: copied flag must never be set for compressed clusters\n",
offset >> s->cluster_bits);
offset &= ~QCOW_OFLAG_COPIED;
}
nb_csectors = ((offset >> s->csize_shift) &
s->csize_mask) + 1;
offset &= s->cluster_offset_mask;
inc_refcounts(bs, refcount_table,
refcount_table_size,
offset & ~511, nb_csectors * 512);
} else {
if (check_copied) {
refcount = get_refcount(bs, (offset & ~QCOW_OFLAG_COPIED) >> s->cluster_bits);
if ((refcount == 1) != ((offset & QCOW_OFLAG_COPIED) != 0)) {
printf("ERROR OFLAG_COPIED: offset=%llx refcount=%d\n",
offset, refcount);
}
}
offset &= ~QCOW_OFLAG_COPIED;
inc_refcounts(bs, refcount_table,
refcount_table_size,
offset, s->cluster_size);
}
}
}
inc_refcounts(bs, refcount_table,
refcount_table_size,
l2_offset,
s->cluster_size);
}
}
qemu_free(l1_table);
qemu_free(l2_table);
return 0;
fail:
printf("ERROR: I/O error in check_refcounts_l1\n");
qemu_free(l1_table);
qemu_free(l2_table);
return -EIO;
}
static void check_refcounts(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
int64_t size;
int nb_clusters, refcount1, refcount2, i;
QCowSnapshot *sn;
uint16_t *refcount_table;
size = bdrv_getlength(s->hd);
nb_clusters = size_to_clusters(s, size);
refcount_table = qemu_mallocz(nb_clusters * sizeof(uint16_t));
/* header */
inc_refcounts(bs, refcount_table, nb_clusters,
0, s->cluster_size);
check_refcounts_l1(bs, refcount_table, nb_clusters,
s->l1_table_offset, s->l1_size, 1);
/* snapshots */
for(i = 0; i < s->nb_snapshots; i++) {
sn = s->snapshots + i;
check_refcounts_l1(bs, refcount_table, nb_clusters,
sn->l1_table_offset, sn->l1_size, 0);
}
inc_refcounts(bs, refcount_table, nb_clusters,
s->snapshots_offset, s->snapshots_size);
/* refcount data */
inc_refcounts(bs, refcount_table, nb_clusters,
s->refcount_table_offset,
s->refcount_table_size * sizeof(uint64_t));
for(i = 0; i < s->refcount_table_size; i++) {
int64_t offset;
offset = s->refcount_table[i];
if (offset != 0) {
inc_refcounts(bs, refcount_table, nb_clusters,
offset, s->cluster_size);
}
}
/* compare ref counts */
for(i = 0; i < nb_clusters; i++) {
refcount1 = get_refcount(bs, i);
refcount2 = refcount_table[i];
if (refcount1 != refcount2)
printf("ERROR cluster %d refcount=%d reference=%d\n",
i, refcount1, refcount2);
}
qemu_free(refcount_table);
}
#if 0
static void dump_refcounts(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
int64_t nb_clusters, k, k1, size;
int refcount;
size = bdrv_getlength(s->hd);
nb_clusters = size_to_clusters(s, size);
for(k = 0; k < nb_clusters;) {
k1 = k;
refcount = get_refcount(bs, k);
k++;
while (k < nb_clusters && get_refcount(bs, k) == refcount)
k++;
printf("%lld: refcount=%d nb=%lld\n", k, refcount, k - k1);
}
}
#endif
#endif
BlockDriver bdrv_qcow2 = {
.format_name = "qcow2",
.instance_size = sizeof(BDRVQcowState),
.bdrv_probe = qcow_probe,
.bdrv_open = qcow_open,
.bdrv_close = qcow_close,
.bdrv_create = qcow_create,
.bdrv_flush = qcow_flush,
.bdrv_is_allocated = qcow_is_allocated,
.bdrv_set_key = qcow_set_key,
.bdrv_make_empty = qcow_make_empty,
.bdrv_aio_read = qcow_aio_read,
.bdrv_aio_write = qcow_aio_write,
.bdrv_aio_cancel = qcow_aio_cancel,
.aiocb_size = sizeof(QCowAIOCB),
.bdrv_write_compressed = qcow_write_compressed,
.bdrv_snapshot_create = qcow_snapshot_create,
.bdrv_snapshot_goto = qcow_snapshot_goto,
.bdrv_snapshot_delete = qcow_snapshot_delete,
.bdrv_snapshot_list = qcow_snapshot_list,
.bdrv_get_info = qcow_get_info,
.bdrv_create2 = qcow_create2,
};