| /* |
| * Null block driver |
| * |
| * Authors: |
| * Fam Zheng <famz@redhat.com> |
| * |
| * Copyright (C) 2014 Red Hat, Inc. |
| * |
| * This work is licensed under the terms of the GNU GPL, version 2 or later. |
| * See the COPYING file in the top-level directory. |
| */ |
| |
| #include "qemu/osdep.h" |
| #include "qapi/error.h" |
| #include "qapi/qmp/qdict.h" |
| #include "qapi/qmp/qstring.h" |
| #include "block/block_int.h" |
| |
| #define NULL_OPT_LATENCY "latency-ns" |
| #define NULL_OPT_ZEROES "read-zeroes" |
| |
| typedef struct { |
| int64_t length; |
| int64_t latency_ns; |
| bool read_zeroes; |
| } BDRVNullState; |
| |
| static QemuOptsList runtime_opts = { |
| .name = "null", |
| .head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head), |
| .desc = { |
| { |
| .name = BLOCK_OPT_SIZE, |
| .type = QEMU_OPT_SIZE, |
| .help = "size of the null block", |
| }, |
| { |
| .name = NULL_OPT_LATENCY, |
| .type = QEMU_OPT_NUMBER, |
| .help = "nanoseconds (approximated) to wait " |
| "before completing request", |
| }, |
| { |
| .name = NULL_OPT_ZEROES, |
| .type = QEMU_OPT_BOOL, |
| .help = "return zeroes when read", |
| }, |
| { /* end of list */ } |
| }, |
| }; |
| |
| static void null_co_parse_filename(const char *filename, QDict *options, |
| Error **errp) |
| { |
| /* This functions only exists so that a null-co:// filename is accepted |
| * with the null-co driver. */ |
| if (strcmp(filename, "null-co://")) { |
| error_setg(errp, "The only allowed filename for this driver is " |
| "'null-co://'"); |
| return; |
| } |
| } |
| |
| static void null_aio_parse_filename(const char *filename, QDict *options, |
| Error **errp) |
| { |
| /* This functions only exists so that a null-aio:// filename is accepted |
| * with the null-aio driver. */ |
| if (strcmp(filename, "null-aio://")) { |
| error_setg(errp, "The only allowed filename for this driver is " |
| "'null-aio://'"); |
| return; |
| } |
| } |
| |
| static int null_file_open(BlockDriverState *bs, QDict *options, int flags, |
| Error **errp) |
| { |
| QemuOpts *opts; |
| BDRVNullState *s = bs->opaque; |
| int ret = 0; |
| |
| opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort); |
| qemu_opts_absorb_qdict(opts, options, &error_abort); |
| s->length = |
| qemu_opt_get_size(opts, BLOCK_OPT_SIZE, 1 << 30); |
| s->latency_ns = |
| qemu_opt_get_number(opts, NULL_OPT_LATENCY, 0); |
| if (s->latency_ns < 0) { |
| error_setg(errp, "latency-ns is invalid"); |
| ret = -EINVAL; |
| } |
| s->read_zeroes = qemu_opt_get_bool(opts, NULL_OPT_ZEROES, false); |
| qemu_opts_del(opts); |
| return ret; |
| } |
| |
| static void null_close(BlockDriverState *bs) |
| { |
| } |
| |
| static int64_t null_getlength(BlockDriverState *bs) |
| { |
| BDRVNullState *s = bs->opaque; |
| return s->length; |
| } |
| |
| static coroutine_fn int null_co_common(BlockDriverState *bs) |
| { |
| BDRVNullState *s = bs->opaque; |
| |
| if (s->latency_ns) { |
| qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, s->latency_ns); |
| } |
| return 0; |
| } |
| |
| static coroutine_fn int null_co_readv(BlockDriverState *bs, |
| int64_t sector_num, int nb_sectors, |
| QEMUIOVector *qiov) |
| { |
| BDRVNullState *s = bs->opaque; |
| |
| if (s->read_zeroes) { |
| qemu_iovec_memset(qiov, 0, 0, nb_sectors * BDRV_SECTOR_SIZE); |
| } |
| |
| return null_co_common(bs); |
| } |
| |
| static coroutine_fn int null_co_writev(BlockDriverState *bs, |
| int64_t sector_num, int nb_sectors, |
| QEMUIOVector *qiov) |
| { |
| return null_co_common(bs); |
| } |
| |
| static coroutine_fn int null_co_flush(BlockDriverState *bs) |
| { |
| return null_co_common(bs); |
| } |
| |
| typedef struct { |
| BlockAIOCB common; |
| QEMUTimer timer; |
| } NullAIOCB; |
| |
| static const AIOCBInfo null_aiocb_info = { |
| .aiocb_size = sizeof(NullAIOCB), |
| }; |
| |
| static void null_bh_cb(void *opaque) |
| { |
| NullAIOCB *acb = opaque; |
| acb->common.cb(acb->common.opaque, 0); |
| qemu_aio_unref(acb); |
| } |
| |
| static void null_timer_cb(void *opaque) |
| { |
| NullAIOCB *acb = opaque; |
| acb->common.cb(acb->common.opaque, 0); |
| timer_deinit(&acb->timer); |
| qemu_aio_unref(acb); |
| } |
| |
| static inline BlockAIOCB *null_aio_common(BlockDriverState *bs, |
| BlockCompletionFunc *cb, |
| void *opaque) |
| { |
| NullAIOCB *acb; |
| BDRVNullState *s = bs->opaque; |
| |
| acb = qemu_aio_get(&null_aiocb_info, bs, cb, opaque); |
| /* Only emulate latency after vcpu is running. */ |
| if (s->latency_ns) { |
| aio_timer_init(bdrv_get_aio_context(bs), &acb->timer, |
| QEMU_CLOCK_REALTIME, SCALE_NS, |
| null_timer_cb, acb); |
| timer_mod_ns(&acb->timer, |
| qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + s->latency_ns); |
| } else { |
| aio_bh_schedule_oneshot(bdrv_get_aio_context(bs), null_bh_cb, acb); |
| } |
| return &acb->common; |
| } |
| |
| static BlockAIOCB *null_aio_readv(BlockDriverState *bs, |
| int64_t sector_num, QEMUIOVector *qiov, |
| int nb_sectors, |
| BlockCompletionFunc *cb, |
| void *opaque) |
| { |
| BDRVNullState *s = bs->opaque; |
| |
| if (s->read_zeroes) { |
| qemu_iovec_memset(qiov, 0, 0, nb_sectors * BDRV_SECTOR_SIZE); |
| } |
| |
| return null_aio_common(bs, cb, opaque); |
| } |
| |
| static BlockAIOCB *null_aio_writev(BlockDriverState *bs, |
| int64_t sector_num, QEMUIOVector *qiov, |
| int nb_sectors, |
| BlockCompletionFunc *cb, |
| void *opaque) |
| { |
| return null_aio_common(bs, cb, opaque); |
| } |
| |
| static BlockAIOCB *null_aio_flush(BlockDriverState *bs, |
| BlockCompletionFunc *cb, |
| void *opaque) |
| { |
| return null_aio_common(bs, cb, opaque); |
| } |
| |
| static int null_reopen_prepare(BDRVReopenState *reopen_state, |
| BlockReopenQueue *queue, Error **errp) |
| { |
| return 0; |
| } |
| |
| static int64_t coroutine_fn null_co_get_block_status(BlockDriverState *bs, |
| int64_t sector_num, |
| int nb_sectors, int *pnum, |
| BlockDriverState **file) |
| { |
| BDRVNullState *s = bs->opaque; |
| off_t start = sector_num * BDRV_SECTOR_SIZE; |
| |
| *pnum = nb_sectors; |
| *file = bs; |
| |
| if (s->read_zeroes) { |
| return BDRV_BLOCK_OFFSET_VALID | start | BDRV_BLOCK_ZERO; |
| } else { |
| return BDRV_BLOCK_OFFSET_VALID | start; |
| } |
| } |
| |
| static void null_refresh_filename(BlockDriverState *bs, QDict *opts) |
| { |
| QINCREF(opts); |
| qdict_del(opts, "filename"); |
| |
| if (!qdict_size(opts)) { |
| snprintf(bs->exact_filename, sizeof(bs->exact_filename), "%s://", |
| bs->drv->format_name); |
| } |
| |
| qdict_put_str(opts, "driver", bs->drv->format_name); |
| bs->full_open_options = opts; |
| } |
| |
| static BlockDriver bdrv_null_co = { |
| .format_name = "null-co", |
| .protocol_name = "null-co", |
| .instance_size = sizeof(BDRVNullState), |
| |
| .bdrv_file_open = null_file_open, |
| .bdrv_parse_filename = null_co_parse_filename, |
| .bdrv_close = null_close, |
| .bdrv_getlength = null_getlength, |
| |
| .bdrv_co_readv = null_co_readv, |
| .bdrv_co_writev = null_co_writev, |
| .bdrv_co_flush_to_disk = null_co_flush, |
| .bdrv_reopen_prepare = null_reopen_prepare, |
| |
| .bdrv_co_get_block_status = null_co_get_block_status, |
| |
| .bdrv_refresh_filename = null_refresh_filename, |
| }; |
| |
| static BlockDriver bdrv_null_aio = { |
| .format_name = "null-aio", |
| .protocol_name = "null-aio", |
| .instance_size = sizeof(BDRVNullState), |
| |
| .bdrv_file_open = null_file_open, |
| .bdrv_parse_filename = null_aio_parse_filename, |
| .bdrv_close = null_close, |
| .bdrv_getlength = null_getlength, |
| |
| .bdrv_aio_readv = null_aio_readv, |
| .bdrv_aio_writev = null_aio_writev, |
| .bdrv_aio_flush = null_aio_flush, |
| .bdrv_reopen_prepare = null_reopen_prepare, |
| |
| .bdrv_co_get_block_status = null_co_get_block_status, |
| |
| .bdrv_refresh_filename = null_refresh_filename, |
| }; |
| |
| static void bdrv_null_init(void) |
| { |
| bdrv_register(&bdrv_null_co); |
| bdrv_register(&bdrv_null_aio); |
| } |
| |
| block_init(bdrv_null_init); |