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block: Introduce bdrv_driver_preadv()

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This is a function that simply calls into the block driver for doing a
read, providing the byte granularity interface we want to eventually
have everywhere, and using whatever interface that driver supports.

For now, this is just a wrapper for calling bs->drv->bdrv_co_readv().

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 11:46:41 +02:00
parent dd7f7ed104
commit 166fe96051
1 changed files with 23 additions and 7 deletions
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30
block/io.c
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@ -797,6 +797,21 @@ int bdrv_pwrite_sync(BlockDriverState *bs, int64_t offset,
return 0;
}
static int coroutine_fn bdrv_driver_preadv(BlockDriverState *bs,
uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov, int flags)
{
BlockDriver *drv = bs->drv;
int64_t sector_num = offset >> BDRV_SECTOR_BITS;
unsigned int 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);
return drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov);
}
static int coroutine_fn bdrv_co_do_copy_on_readv(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
{
@ -833,8 +848,9 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(BlockDriverState *bs,
qemu_iovec_init_external(&bounce_qiov, &iov, 1);
ret = drv->bdrv_co_readv(bs, cluster_sector_num, cluster_nb_sectors,
&bounce_qiov);
ret = bdrv_driver_preadv(bs, cluster_sector_num * BDRV_SECTOR_SIZE,
cluster_nb_sectors * BDRV_SECTOR_SIZE,
&bounce_qiov, 0);
if (ret < 0) {
goto err;
}
@ -877,7 +893,6 @@ static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs,
BdrvTrackedRequest *req, int64_t offset, unsigned int bytes,
int64_t align, QEMUIOVector *qiov, int flags)
{
BlockDriver *drv = bs->drv;
int ret;
int64_t sector_num = offset >> BDRV_SECTOR_BITS;
@ -918,7 +933,7 @@ static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs,
/* Forward the request to the BlockDriver */
if (!bs->zero_beyond_eof) {
ret = drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov);
ret = bdrv_driver_preadv(bs, offset, bytes, qiov, 0);
} else {
/* Read zeros after EOF */
int64_t total_sectors, max_nb_sectors;
@ -932,7 +947,7 @@ static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs,
max_nb_sectors = ROUND_UP(MAX(0, total_sectors - sector_num),
align >> BDRV_SECTOR_BITS);
if (nb_sectors < max_nb_sectors) {
ret = drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov);
ret = bdrv_driver_preadv(bs, offset, bytes, qiov, 0);
} else if (max_nb_sectors > 0) {
QEMUIOVector local_qiov;
@ -940,8 +955,9 @@ static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs,
qemu_iovec_concat(&local_qiov, qiov, 0,
max_nb_sectors * BDRV_SECTOR_SIZE);
ret = drv->bdrv_co_readv(bs, sector_num, max_nb_sectors,
&local_qiov);
ret = bdrv_driver_preadv(bs, offset,
max_nb_sectors * BDRV_SECTOR_SIZE,
&local_qiov, 0);
qemu_iovec_destroy(&local_qiov);
} else {