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block: Convert bdrv_co_preadv/pwritev to BdrvChild

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This is the final patch for converting the common I/O path to take
a BdrvChild parameter instead of BlockDriverState.

The completion of this conversion means that all users that perform I/O
on an image need to actually hold a reference (in the form of BdrvChild,
possible as part of a BlockBackend) to that image. This also protects
against inconsistent use of BlockBackend vs. BlockDriverState functions
because direct use of a BlockDriverState isn't possible any more and
blk->root is private for block-backends.c.

In addition, we can now distinguish different users in the I/O path,
and the future op blockers work is going to add assertions based on
permissions stored in BdrvChild.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Kevin Wolf 2016-06-20 21:31:46 +02:00
parent e293b7a3df
commit a03ef88f77
12 changed files with 38 additions and 37 deletions
Download patch file Download diff file Expand all files Collapse all files

25
block/io.c
View file

@ -566,11 +566,11 @@ static void coroutine_fn bdrv_rw_co_entry(void *opaque)
RwCo *rwco = opaque;
if (!rwco->is_write) {
rwco->ret = bdrv_co_preadv(rwco->child->bs, rwco->offset,
rwco->ret = bdrv_co_preadv(rwco->child, rwco->offset,
rwco->qiov->size, rwco->qiov,
rwco->flags);
} else {
rwco->ret = bdrv_co_pwritev(rwco->child->bs, rwco->offset,
rwco->ret = bdrv_co_pwritev(rwco->child, rwco->offset,
rwco->qiov->size, rwco->qiov,
rwco->flags);
}
@ -1061,10 +1061,11 @@ out:
/*
* Handle a read request in coroutine context
*/
int coroutine_fn bdrv_co_preadv(BlockDriverState *bs,
int coroutine_fn bdrv_co_preadv(BdrvChild *child,
int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
BdrvRequestFlags flags)
{
BlockDriverState *bs = child->bs;
BlockDriver *drv = bs->drv;
BdrvTrackedRequest req;
@ -1137,7 +1138,7 @@ static int coroutine_fn bdrv_co_do_readv(BdrvChild *child,
return -EINVAL;
}
return bdrv_co_preadv(child->bs, sector_num << BDRV_SECTOR_BITS,
return bdrv_co_preadv(child, sector_num << BDRV_SECTOR_BITS,
nb_sectors << BDRV_SECTOR_BITS, qiov, flags);
}
@ -1406,10 +1407,11 @@ fail:
/*
* Handle a write request in coroutine context
*/
int coroutine_fn bdrv_co_pwritev(BlockDriverState *bs,
int coroutine_fn bdrv_co_pwritev(BdrvChild *child,
int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
BdrvRequestFlags flags)
{
BlockDriverState *bs = child->bs;
BdrvTrackedRequest req;
uint64_t align = bs->bl.request_alignment;
uint8_t *head_buf = NULL;
@ -1543,7 +1545,7 @@ static int coroutine_fn bdrv_co_do_writev(BdrvChild *child,
return -EINVAL;
}
return bdrv_co_pwritev(child->bs, sector_num << BDRV_SECTOR_BITS,
return bdrv_co_pwritev(child, sector_num << BDRV_SECTOR_BITS,
nb_sectors << BDRV_SECTOR_BITS, qiov, flags);
}
@ -1555,17 +1557,16 @@ int coroutine_fn bdrv_co_writev(BdrvChild *child, int64_t sector_num,
return bdrv_co_do_writev(child, sector_num, nb_sectors, qiov, 0);
}
int coroutine_fn bdrv_co_pwrite_zeroes(BlockDriverState *bs,
int64_t offset, int count,
BdrvRequestFlags flags)
int coroutine_fn bdrv_co_pwrite_zeroes(BdrvChild *child, int64_t offset,
int count, BdrvRequestFlags flags)
{
trace_bdrv_co_pwrite_zeroes(bs, offset, count, flags);
trace_bdrv_co_pwrite_zeroes(child->bs, offset, count, flags);
if (!(bs->open_flags & BDRV_O_UNMAP)) {
if (!(child->bs->open_flags & BDRV_O_UNMAP)) {
flags &= ~BDRV_REQ_MAY_UNMAP;
}
return bdrv_co_pwritev(bs, offset, count, NULL,
return bdrv_co_pwritev(child, offset, count, NULL,
BDRV_REQ_ZERO_WRITE | flags);
}