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block: Introduce .bdrv_co_preadv/pwritev BlockDriver function

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Many parts of the block layer are already byte granularity. The block
driver interface, however, was still missing an interface that allows
making use of this. This patch introduces a new BlockDriver interface,
which is based on coroutines, vectored, has flags and uses a byte
granularity. This is now the preferred interface for new drivers.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
This commit is contained in:
Kevin Wolf 2016-04-25 11:25:18 +02:00
parent cab3a3563c
commit 3fb06697ae
2 changed files with 26 additions and 6 deletions
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28
block/io.c
View file

@ -803,8 +803,15 @@ static int coroutine_fn bdrv_driver_preadv(BlockDriverState *bs,
QEMUIOVector *qiov, int flags)
{
BlockDriver *drv = bs->drv;
int64_t sector_num = offset >> BDRV_SECTOR_BITS;
unsigned int nb_sectors = bytes >> BDRV_SECTOR_BITS;
int64_t sector_num;
unsigned int nb_sectors;
if (drv->bdrv_co_preadv) {
return drv->bdrv_co_preadv(bs, offset, bytes, qiov, flags);
}
sector_num = offset >> BDRV_SECTOR_BITS;
nb_sectors = bytes >> BDRV_SECTOR_BITS;
assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
@ -834,10 +841,18 @@ static int coroutine_fn bdrv_driver_pwritev(BlockDriverState *bs,
QEMUIOVector *qiov, int flags)
{
BlockDriver *drv = bs->drv;
int64_t sector_num = offset >> BDRV_SECTOR_BITS;
unsigned int nb_sectors = bytes >> BDRV_SECTOR_BITS;
int64_t sector_num;
unsigned int nb_sectors;
int ret;
if (drv->bdrv_co_pwritev) {
ret = drv->bdrv_co_pwritev(bs, offset, bytes, qiov, flags);
goto emulate_flags;
}
sector_num = offset >> BDRV_SECTOR_BITS;
nb_sectors = bytes >> BDRV_SECTOR_BITS;
assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
assert((bytes >> BDRV_SECTOR_BITS) <= BDRV_REQUEST_MAX_SECTORS);
@ -857,13 +872,14 @@ static int coroutine_fn bdrv_driver_pwritev(BlockDriverState *bs,
acb = bs->drv->bdrv_aio_writev(bs, sector_num, qiov, nb_sectors,
bdrv_co_io_em_complete, &co);
if (acb == NULL) {
return -EIO;
ret = -EIO;
} else {
qemu_coroutine_yield();
return co.ret;
ret = co.ret;
}
}
emulate_flags:
if (ret == 0 && (flags & BDRV_REQ_FUA) &&
!(drv->supported_write_flags & BDRV_REQ_FUA))
{

4
include/block/block_int.h
View file

@ -153,10 +153,14 @@ struct BlockDriver {
int coroutine_fn (*bdrv_co_readv)(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
int coroutine_fn (*bdrv_co_preadv)(BlockDriverState *bs,
uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags);
int coroutine_fn (*bdrv_co_writev)(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
int coroutine_fn (*bdrv_co_writev_flags)(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov, int flags);
int coroutine_fn (*bdrv_co_pwritev)(BlockDriverState *bs,
uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags);
int supported_write_flags;