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block: unify flush implementations 

Add coroutine support for flush and apply the same emulation that
we already do for read/write.  bdrv_aio_flush is simplified to always
go through a coroutine.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Paolo Bonzini 2011-10-17 12:32:12 +02:00 committed by Kevin Wolf
parent 5cce43bb28
commit 07f0761574
3 changed files with 77 additions and 91 deletions
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166
block.c
View File

@ -53,17 +53,12 @@ static BlockDriverAIOCB *bdrv_aio_readv_em(BlockDriverState *bs,
static BlockDriverAIOCB *bdrv_aio_writev_em(BlockDriverState *bs,
int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
BlockDriverCompletionFunc *cb, void *opaque);
static BlockDriverAIOCB *bdrv_aio_flush_em(BlockDriverState *bs,
BlockDriverCompletionFunc *cb, void *opaque);
static BlockDriverAIOCB *bdrv_aio_noop_em(BlockDriverState *bs,
BlockDriverCompletionFunc *cb, void *opaque);
static int coroutine_fn bdrv_co_readv_em(BlockDriverState *bs,
int64_t sector_num, int nb_sectors,
QEMUIOVector *iov);
static int coroutine_fn bdrv_co_writev_em(BlockDriverState *bs,
int64_t sector_num, int nb_sectors,
QEMUIOVector *iov);
static int coroutine_fn bdrv_co_flush_em(BlockDriverState *bs);
static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs,
@ -203,9 +198,6 @@ void bdrv_register(BlockDriver *bdrv)
}
}
if (!bdrv->bdrv_aio_flush)
bdrv->bdrv_aio_flush = bdrv_aio_flush_em;
QLIST_INSERT_HEAD(&bdrv_drivers, bdrv, list);
}
@ -1027,11 +1019,6 @@ static int bdrv_check_request(BlockDriverState *bs, int64_t sector_num,
nb_sectors * BDRV_SECTOR_SIZE);
}
static inline bool bdrv_has_async_flush(BlockDriver *drv)
{
return drv->bdrv_aio_flush != bdrv_aio_flush_em;
}
typedef struct RwCo {
BlockDriverState *bs;
int64_t sector_num;
@ -1759,33 +1746,6 @@ const char *bdrv_get_device_name(BlockDriverState *bs)
return bs->device_name;
}
int bdrv_flush(BlockDriverState *bs)
{
if (bs->open_flags & BDRV_O_NO_FLUSH) {
return 0;
}
if (bs->drv && bdrv_has_async_flush(bs->drv) && qemu_in_coroutine()) {
return bdrv_co_flush_em(bs);
}
if (bs->drv && bs->drv->bdrv_flush) {
return bs->drv->bdrv_flush(bs);
}
/*
* Some block drivers always operate in either writethrough or unsafe mode
* and don't support bdrv_flush therefore. Usually qemu doesn't know how
* the server works (because the behaviour is hardcoded or depends on
* server-side configuration), so we can't ensure that everything is safe
* on disk. Returning an error doesn't work because that would break guests
* even if the server operates in writethrough mode.
*
* Let's hope the user knows what he's doing.
*/
return 0;
}
void bdrv_flush_all(void)
{
BlockDriverState *bs;
@ -2610,22 +2570,6 @@ fail:
return -1;
}
BlockDriverAIOCB *bdrv_aio_flush(BlockDriverState *bs,
BlockDriverCompletionFunc *cb, void *opaque)
{
BlockDriver *drv = bs->drv;
trace_bdrv_aio_flush(bs, opaque);
if (bs->open_flags & BDRV_O_NO_FLUSH) {
return bdrv_aio_noop_em(bs, cb, opaque);
}
if (!drv)
return NULL;
return drv->bdrv_aio_flush(bs, cb, opaque);
}
void bdrv_aio_cancel(BlockDriverAIOCB *acb)
{
acb->pool->cancel(acb);
@ -2785,41 +2729,28 @@ static BlockDriverAIOCB *bdrv_co_aio_rw_vector(BlockDriverState *bs,
return &acb->common;
}
static BlockDriverAIOCB *bdrv_aio_flush_em(BlockDriverState *bs,
BlockDriverCompletionFunc *cb, void *opaque)
static void coroutine_fn bdrv_aio_flush_co_entry(void *opaque)
{
BlockDriverAIOCBSync *acb;
BlockDriverAIOCBCoroutine *acb = opaque;
BlockDriverState *bs = acb->common.bs;
acb = qemu_aio_get(&bdrv_em_aio_pool, bs, cb, opaque);
acb->is_write = 1; /* don't bounce in the completion hadler */
acb->qiov = NULL;
acb->bounce = NULL;
acb->ret = 0;
if (!acb->bh)
acb->bh = qemu_bh_new(bdrv_aio_bh_cb, acb);
bdrv_flush(bs);
acb->req.error = bdrv_co_flush(bs);
acb->bh = qemu_bh_new(bdrv_co_em_bh, acb);
qemu_bh_schedule(acb->bh);
return &acb->common;
}
static BlockDriverAIOCB *bdrv_aio_noop_em(BlockDriverState *bs,
BlockDriverAIOCB *bdrv_aio_flush(BlockDriverState *bs,
BlockDriverCompletionFunc *cb, void *opaque)
{
BlockDriverAIOCBSync *acb;
trace_bdrv_aio_flush(bs, opaque);
acb = qemu_aio_get(&bdrv_em_aio_pool, bs, cb, opaque);
acb->is_write = 1; /* don't bounce in the completion handler */
acb->qiov = NULL;
acb->bounce = NULL;
acb->ret = 0;
Coroutine *co;
BlockDriverAIOCBCoroutine *acb;
if (!acb->bh) {
acb->bh = qemu_bh_new(bdrv_aio_bh_cb, acb);
}
acb = qemu_aio_get(&bdrv_em_co_aio_pool, bs, cb, opaque);
co = qemu_coroutine_create(bdrv_aio_flush_co_entry);
qemu_coroutine_enter(co, acb);
qemu_bh_schedule(acb->bh);
return &acb->common;
}
@ -2916,19 +2847,72 @@ static int coroutine_fn bdrv_co_writev_em(BlockDriverState *bs,
return bdrv_co_io_em(bs, sector_num, nb_sectors, iov, true);
}
static int coroutine_fn bdrv_co_flush_em(BlockDriverState *bs)
static void coroutine_fn bdrv_flush_co_entry(void *opaque)
{
CoroutineIOCompletion co = {
.coroutine = qemu_coroutine_self(),
};
BlockDriverAIOCB *acb;
RwCo *rwco = opaque;
acb = bdrv_aio_flush(bs, bdrv_co_io_em_complete, &co);
if (!acb) {
return -EIO;
rwco->ret = bdrv_co_flush(rwco->bs);
}
int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
{
if (bs->open_flags & BDRV_O_NO_FLUSH) {
return 0;
} else if (!bs->drv) {
return 0;
} else if (bs->drv->bdrv_co_flush) {
return bs->drv->bdrv_co_flush(bs);
} else if (bs->drv->bdrv_aio_flush) {
BlockDriverAIOCB *acb;
CoroutineIOCompletion co = {
.coroutine = qemu_coroutine_self(),
};
acb = bs->drv->bdrv_aio_flush(bs, bdrv_co_io_em_complete, &co);
if (acb == NULL) {
return -EIO;
} else {
qemu_coroutine_yield();
return co.ret;
}
} else if (bs->drv->bdrv_flush) {
return bs->drv->bdrv_flush(bs);
} else {
/*
* Some block drivers always operate in either writethrough or unsafe
* mode and don't support bdrv_flush therefore. Usually qemu doesn't
* know how the server works (because the behaviour is hardcoded or
* depends on server-side configuration), so we can't ensure that
* everything is safe on disk. Returning an error doesn't work because
* that would break guests even if the server operates in writethrough
* mode.
*
* Let's hope the user knows what he's doing.
*/
return 0;
}
qemu_coroutine_yield();
return co.ret;
}
int bdrv_flush(BlockDriverState *bs)
{
Coroutine *co;
RwCo rwco = {
.bs = bs,
.ret = NOT_DONE,
};
if (qemu_in_coroutine()) {
/* Fast-path if already in coroutine context */
bdrv_flush_co_entry(&rwco);
} else {
co = qemu_coroutine_create(bdrv_flush_co_entry);
qemu_coroutine_enter(co, &rwco);
while (rwco.ret == NOT_DONE) {
qemu_aio_wait();
}
}
return rwco.ret;
}
/**************************************************************/

1
block.h
View File

@ -191,6 +191,7 @@ BlockDriverAIOCB *bdrv_aio_ioctl(BlockDriverState *bs,
/* Ensure contents are flushed to disk. */
int bdrv_flush(BlockDriverState *bs);
int coroutine_fn bdrv_co_flush(BlockDriverState *bs);
void bdrv_flush_all(void);
void bdrv_close_all(void);

1
block_int.h
View File

@ -83,6 +83,7 @@ struct BlockDriver {
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
int coroutine_fn (*bdrv_co_writev)(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
int coroutine_fn (*bdrv_co_flush)(BlockDriverState *bs);
int (*bdrv_aio_multiwrite)(BlockDriverState *bs, BlockRequest *reqs,
int num_reqs);