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block: Emulate AIO functions with bdrv_co_readv/writev

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Use the bdrv_co_readv/writev callbacks to implement bdrv_aio_readv/writev and
bdrv_read/write if a driver provides the coroutine version instead of the
synchronous or AIO version.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2011-06-30 10:05:46 +02:00
parent da1fa91d6c
commit 6848542018
1 changed files with 97 additions and 1 deletions
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98
block.c
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@ -28,6 +28,7 @@
#include "block_int.h"
#include "module.h"
#include "qemu-objects.h"
#include "qemu-coroutine.h"
#ifdef CONFIG_BSD
#include <sys/types.h>
@ -57,6 +58,12 @@ static int bdrv_read_em(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors);
static int bdrv_write_em(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors);
static BlockDriverAIOCB *bdrv_co_aio_readv_em(BlockDriverState *bs,
int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
BlockDriverCompletionFunc *cb, void *opaque);
static BlockDriverAIOCB *bdrv_co_aio_writev_em(BlockDriverState *bs,
int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
BlockDriverCompletionFunc *cb, void *opaque);
static QTAILQ_HEAD(, BlockDriverState) bdrv_states =
QTAILQ_HEAD_INITIALIZER(bdrv_states);
@ -169,7 +176,13 @@ void path_combine(char *dest, int dest_size,
void bdrv_register(BlockDriver *bdrv)
{
if (!bdrv->bdrv_aio_readv) {
if (bdrv->bdrv_co_readv) {
/* Emulate AIO by coroutines, and sync by AIO */
bdrv->bdrv_aio_readv = bdrv_co_aio_readv_em;
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;
@ -2614,6 +2627,89 @@ static BlockDriverAIOCB *bdrv_aio_writev_em(BlockDriverState *bs,
return bdrv_aio_rw_vector(bs, sector_num, qiov, nb_sectors, cb, opaque, 1);
}
typedef struct BlockDriverAIOCBCoroutine {
BlockDriverAIOCB common;
BlockRequest req;
bool is_write;
QEMUBH* bh;
} BlockDriverAIOCBCoroutine;
static void bdrv_aio_co_cancel_em(BlockDriverAIOCB *blockacb)
{
qemu_aio_flush();
}
static AIOPool bdrv_em_co_aio_pool = {
.aiocb_size = sizeof(BlockDriverAIOCBCoroutine),
.cancel = bdrv_aio_co_cancel_em,
};
static void bdrv_co_rw_bh(void *opaque)
{
BlockDriverAIOCBCoroutine *acb = opaque;
acb->common.cb(acb->common.opaque, acb->req.error);
qemu_bh_delete(acb->bh);
qemu_aio_release(acb);
}
static void coroutine_fn bdrv_co_rw(void *opaque)
{
BlockDriverAIOCBCoroutine *acb = opaque;
BlockDriverState *bs = acb->common.bs;
if (!acb->is_write) {
acb->req.error = bs->drv->bdrv_co_readv(bs, acb->req.sector,
acb->req.nb_sectors, acb->req.qiov);
} else {
acb->req.error = bs->drv->bdrv_co_writev(bs, acb->req.sector,
acb->req.nb_sectors, acb->req.qiov);
}
acb->bh = qemu_bh_new(bdrv_co_rw_bh, acb);
qemu_bh_schedule(acb->bh);
}
static BlockDriverAIOCB *bdrv_co_aio_rw_vector(BlockDriverState *bs,
int64_t sector_num,
QEMUIOVector *qiov,
int nb_sectors,
BlockDriverCompletionFunc *cb,
void *opaque,
bool is_write)
{
Coroutine *co;
BlockDriverAIOCBCoroutine *acb;
acb = qemu_aio_get(&bdrv_em_co_aio_pool, bs, cb, opaque);
acb->req.sector = sector_num;
acb->req.nb_sectors = nb_sectors;
acb->req.qiov = qiov;
acb->is_write = is_write;
co = qemu_coroutine_create(bdrv_co_rw);
qemu_coroutine_enter(co, acb);
return &acb->common;
}
static BlockDriverAIOCB *bdrv_co_aio_readv_em(BlockDriverState *bs,
int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
BlockDriverCompletionFunc *cb, void *opaque)
{
return bdrv_co_aio_rw_vector(bs, sector_num, qiov, nb_sectors, cb, opaque,
false);
}
static BlockDriverAIOCB *bdrv_co_aio_writev_em(BlockDriverState *bs,
int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
BlockDriverCompletionFunc *cb, void *opaque)
{
return bdrv_co_aio_rw_vector(bs, sector_num, qiov, nb_sectors, cb, opaque,
true);
}
static BlockDriverAIOCB *bdrv_aio_flush_em(BlockDriverState *bs,
BlockDriverCompletionFunc *cb, void *opaque)
{