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block: Add bdrv_co_readv/writev emulation 

In order to be able to call bdrv_co_readv/writev for drivers that don't
implement the functions natively, add an emulation that uses the AIO functions
to implement them.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2011-07-15 13:50:26 +02:00
parent 6848542018
commit f9f05dc58c
2 changed files with 76 additions and 8 deletions
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83
block.c
View File

@ -64,6 +64,12 @@ static BlockDriverAIOCB *bdrv_co_aio_readv_em(BlockDriverState *bs,
static BlockDriverAIOCB *bdrv_co_aio_writev_em(BlockDriverState *bs,
int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
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 QTAILQ_HEAD(, BlockDriverState) bdrv_states =
QTAILQ_HEAD_INITIALIZER(bdrv_states);
@ -182,14 +188,19 @@ void bdrv_register(BlockDriver *bdrv)
bdrv->bdrv_aio_writev = bdrv_co_aio_writev_em;
bdrv->bdrv_read = bdrv_read_em;
bdrv->bdrv_write = bdrv_write_em;
} else if (!bdrv->bdrv_aio_readv) {
/* add AIO emulation layer */
bdrv->bdrv_aio_readv = bdrv_aio_readv_em;
bdrv->bdrv_aio_writev = bdrv_aio_writev_em;
} else if (!bdrv->bdrv_read) {
/* add synchronous IO emulation layer */
bdrv->bdrv_read = bdrv_read_em;
bdrv->bdrv_write = bdrv_write_em;
} else {
bdrv->bdrv_co_readv = bdrv_co_readv_em;
bdrv->bdrv_co_writev = bdrv_co_writev_em;
if (!bdrv->bdrv_aio_readv) {
/* add AIO emulation layer */
bdrv->bdrv_aio_readv = bdrv_aio_readv_em;
bdrv->bdrv_aio_writev = bdrv_aio_writev_em;
} else if (!bdrv->bdrv_read) {
/* add synchronous IO emulation layer */
bdrv->bdrv_read = bdrv_read_em;
bdrv->bdrv_write = bdrv_write_em;
}
}
if (!bdrv->bdrv_aio_flush)
@ -2855,6 +2866,62 @@ void qemu_aio_release(void *p)
pool->free_aiocb = acb;
}
/**************************************************************/
/* Coroutine block device emulation */
typedef struct CoroutineIOCompletion {
Coroutine *coroutine;
int ret;
} CoroutineIOCompletion;
static void bdrv_co_io_em_complete(void *opaque, int ret)
{
CoroutineIOCompletion *co = opaque;
co->ret = ret;
qemu_coroutine_enter(co->coroutine, NULL);
}
static int coroutine_fn bdrv_co_io_em(BlockDriverState *bs, int64_t sector_num,
int nb_sectors, QEMUIOVector *iov,
bool is_write)
{
CoroutineIOCompletion co = {
.coroutine = qemu_coroutine_self(),
};
BlockDriverAIOCB *acb;
if (is_write) {
acb = bdrv_aio_writev(bs, sector_num, iov, nb_sectors,
bdrv_co_io_em_complete, &co);
} else {
acb = bdrv_aio_readv(bs, sector_num, iov, nb_sectors,
bdrv_co_io_em_complete, &co);
}
trace_bdrv_co_io(is_write, acb);
if (!acb) {
return -EIO;
}
qemu_coroutine_yield();
return co.ret;
}
static int coroutine_fn bdrv_co_readv_em(BlockDriverState *bs,
int64_t sector_num, int nb_sectors,
QEMUIOVector *iov)
{
return bdrv_co_io_em(bs, sector_num, nb_sectors, iov, false);
}
static int coroutine_fn bdrv_co_writev_em(BlockDriverState *bs,
int64_t sector_num, int nb_sectors,
QEMUIOVector *iov)
{
return bdrv_co_io_em(bs, sector_num, nb_sectors, iov, true);
}
/**************************************************************/
/* removable device support */

1
trace-events
View File

@ -68,6 +68,7 @@ disable bdrv_aio_writev(void *bs, int64_t sector_num, int nb_sectors, void *opaq
disable bdrv_set_locked(void *bs, int locked) "bs %p locked %d"
disable bdrv_co_readv(void *bs, int64_t sector_num, int nb_sector) "bs %p sector_num %"PRId64" nb_sectors %d"
disable bdrv_co_writev(void *bs, int64_t sector_num, int nb_sector) "bs %p sector_num %"PRId64" nb_sectors %d"
disable bdrv_co_io(int is_write, void *acb) "is_write %d acb %p"
# hw/virtio-blk.c
disable virtio_blk_req_complete(void *req, int status) "req %p status %d"