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block: Introduce bdrv_co_flush_to_os

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qcow2 has a writeback metadata cache, so flushing a qcow2 image actually
consists of writing back that cache to the protocol and only then flushes the
protocol in order to get everything stable on disk.

This introduces a separate bdrv_co_flush_to_os to reflect the split.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2011-11-10 18:10:11 +01:00
parent c68b89acd6
commit eb489bb1ec
3 changed files with 27 additions and 3 deletions
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13
block.c
View File

@ -2789,11 +2789,22 @@ static void coroutine_fn bdrv_flush_co_entry(void *opaque)
int coroutine_fn bdrv_co_flush(BlockDriverState *bs) int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
{ {
int ret;
if (bs->open_flags & BDRV_O_NO_FLUSH) { if (bs->open_flags & BDRV_O_NO_FLUSH) {
return 0; return 0;
} else if (!bs->drv) { } else if (!bs->drv) {
return 0; return 0;
} else if (bs->drv->bdrv_co_flush_to_disk) { }
if (bs->drv->bdrv_co_flush_to_os) {
ret = bs->drv->bdrv_co_flush_to_os(bs);
if (ret < 0) {
return ret;
}
}
if (bs->drv->bdrv_co_flush_to_disk) {
return bs->drv->bdrv_co_flush_to_disk(bs); return bs->drv->bdrv_co_flush_to_disk(bs);
} else if (bs->drv->bdrv_aio_flush) { } else if (bs->drv->bdrv_aio_flush) {
BlockDriverAIOCB *acb; BlockDriverAIOCB *acb;

10
block/qcow2.c
View File

@ -1105,7 +1105,7 @@ fail:
return ret; return ret;
} }
static int qcow2_co_flush(BlockDriverState *bs) static int qcow2_co_flush_to_os(BlockDriverState *bs)
{ {
BDRVQcowState *s = bs->opaque; BDRVQcowState *s = bs->opaque;
int ret; int ret;
@ -1124,6 +1124,11 @@ static int qcow2_co_flush(BlockDriverState *bs)
} }
qemu_co_mutex_unlock(&s->lock); qemu_co_mutex_unlock(&s->lock);
return 0;
}
static int qcow2_co_flush_to_disk(BlockDriverState *bs)
{
return bdrv_co_flush(bs->file); return bdrv_co_flush(bs->file);
} }
@ -1245,7 +1250,8 @@ static BlockDriver bdrv_qcow2 = {
.bdrv_co_readv = qcow2_co_readv, .bdrv_co_readv = qcow2_co_readv,
.bdrv_co_writev = qcow2_co_writev, .bdrv_co_writev = qcow2_co_writev,
.bdrv_co_flush_to_disk = qcow2_co_flush, .bdrv_co_flush_to_os = qcow2_co_flush_to_os,
.bdrv_co_flush_to_disk = qcow2_co_flush_to_disk,
.bdrv_co_discard = qcow2_co_discard, .bdrv_co_discard = qcow2_co_discard,
.bdrv_truncate = qcow2_truncate, .bdrv_truncate = qcow2_truncate,

7
block_int.h
View File

@ -93,6 +93,13 @@ struct BlockDriver {
*/ */
int coroutine_fn (*bdrv_co_flush_to_disk)(BlockDriverState *bs); int coroutine_fn (*bdrv_co_flush_to_disk)(BlockDriverState *bs);
/*
* Flushes all internal caches to the OS. The data may still sit in a
* writeback cache of the host OS, but it will survive a crash of the qemu
* process.
*/
int coroutine_fn (*bdrv_co_flush_to_os)(BlockDriverState *bs);
int (*bdrv_aio_multiwrite)(BlockDriverState *bs, BlockRequest *reqs, int (*bdrv_aio_multiwrite)(BlockDriverState *bs, BlockRequest *reqs,
int num_reqs); int num_reqs);
int (*bdrv_merge_requests)(BlockDriverState *bs, BlockRequest* a, int (*bdrv_merge_requests)(BlockDriverState *bs, BlockRequest* a,