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block: switch bdrv_read()/bdrv_write() to coroutines

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The bdrv_read()/bdrv_write() functions call .bdrv_read()/.bdrv_write().
They should go through bdrv_co_do_readv() and bdrv_co_do_writev()
instead in order to unify request processing code across sync, aio, and
coroutine interfaces.  This is also an important step towards removing
BlockDriverState .bdrv_read()/.bdrv_write() in the future.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2011-10-13 13:08:22 +01:00 committed by Kevin Wolf
parent c5fbe57111
commit 1c9805a398
1 changed files with 64 additions and 52 deletions
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116
block.c
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@ -44,6 +44,8 @@
#include <windows.h>
#endif
#define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */
static void bdrv_dev_change_media_cb(BlockDriverState *bs, bool load);
static BlockDriverAIOCB *bdrv_aio_readv_em(BlockDriverState *bs,
int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
@ -74,6 +76,8 @@ static int coroutine_fn bdrv_co_writev_em(BlockDriverState *bs,
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,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
static QTAILQ_HEAD(, BlockDriverState) bdrv_states =
QTAILQ_HEAD_INITIALIZER(bdrv_states);
@ -1042,30 +1046,69 @@ 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;
int nb_sectors;
QEMUIOVector *qiov;
bool is_write;
int ret;
} RwCo;
static void coroutine_fn bdrv_rw_co_entry(void *opaque)
{
RwCo *rwco = opaque;
if (!rwco->is_write) {
rwco->ret = bdrv_co_do_readv(rwco->bs, rwco->sector_num,
rwco->nb_sectors, rwco->qiov);
} else {
rwco->ret = bdrv_co_do_writev(rwco->bs, rwco->sector_num,
rwco->nb_sectors, rwco->qiov);
}
}
/*
* Process a synchronous request using coroutines
*/
static int bdrv_rw_co(BlockDriverState *bs, int64_t sector_num, uint8_t *buf,
int nb_sectors, bool is_write)
{
QEMUIOVector qiov;
struct iovec iov = {
.iov_base = (void *)buf,
.iov_len = nb_sectors * BDRV_SECTOR_SIZE,
};
Coroutine *co;
RwCo rwco = {
.bs = bs,
.sector_num = sector_num,
.nb_sectors = nb_sectors,
.qiov = &qiov,
.is_write = is_write,
.ret = NOT_DONE,
};
qemu_iovec_init_external(&qiov, &iov, 1);
if (qemu_in_coroutine()) {
/* Fast-path if already in coroutine context */
bdrv_rw_co_entry(&rwco);
} else {
co = qemu_coroutine_create(bdrv_rw_co_entry);
qemu_coroutine_enter(co, &rwco);
while (rwco.ret == NOT_DONE) {
qemu_aio_wait();
}
}
return rwco.ret;
}
/* return < 0 if error. See bdrv_write() for the return codes */
int bdrv_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
{
BlockDriver *drv = bs->drv;
if (!drv)
return -ENOMEDIUM;
if (bdrv_has_async_rw(drv) && qemu_in_coroutine()) {
QEMUIOVector qiov;
struct iovec iov = {
.iov_base = (void *)buf,
.iov_len = nb_sectors * BDRV_SECTOR_SIZE,
};
qemu_iovec_init_external(&qiov, &iov, 1);
return bdrv_co_readv(bs, sector_num, nb_sectors, &qiov);
}
if (bdrv_check_request(bs, sector_num, nb_sectors))
return -EIO;
return drv->bdrv_read(bs, sector_num, buf, nb_sectors);
return bdrv_rw_co(bs, sector_num, buf, nb_sectors, false);
}
static void set_dirty_bitmap(BlockDriverState *bs, int64_t sector_num,
@ -1105,36 +1148,7 @@ static void set_dirty_bitmap(BlockDriverState *bs, int64_t sector_num,
int bdrv_write(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors)
{
BlockDriver *drv = bs->drv;
if (!bs->drv)
return -ENOMEDIUM;
if (bdrv_has_async_rw(drv) && qemu_in_coroutine()) {
QEMUIOVector qiov;
struct iovec iov = {
.iov_base = (void *)buf,
.iov_len = nb_sectors * BDRV_SECTOR_SIZE,
};
qemu_iovec_init_external(&qiov, &iov, 1);
return bdrv_co_writev(bs, sector_num, nb_sectors, &qiov);
}
if (bs->read_only)
return -EACCES;
if (bdrv_check_request(bs, sector_num, nb_sectors))
return -EIO;
if (bs->dirty_bitmap) {
set_dirty_bitmap(bs, sector_num, nb_sectors, 1);
}
if (bs->wr_highest_sector < sector_num + nb_sectors - 1) {
bs->wr_highest_sector = sector_num + nb_sectors - 1;
}
return drv->bdrv_write(bs, sector_num, buf, nb_sectors);
return bdrv_rw_co(bs, sector_num, (uint8_t *)buf, nb_sectors, true);
}
int bdrv_pread(BlockDriverState *bs, int64_t offset,
@ -2912,8 +2926,6 @@ static void bdrv_rw_em_cb(void *opaque, int ret)
*(int *)opaque = ret;
}
#define NOT_DONE 0x7fffffff
static int bdrv_read_em(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
{