motorhead/qemu
1
0
Fork 0
mirror of https://github.com/Motorhead1991/qemu.git synced 2025-08-03 07:43:54 -06:00
Code Issues Projects Releases Packages Wiki Activity Actions

block: Convert bdrv_refresh_total_sectors() to co_wrapper_mixed

Browse source 
BlockDriver->bdrv_getlength is categorized as IO callback, and it
currently doesn't run in a coroutine. We should let it take a graph
rdlock since the callback traverses the block nodes graph, which however
is only possible in a coroutine.

Therefore turn it into a co_wrapper to move the actual function into a
coroutine where the lock can be taken.

Because now this function creates a new coroutine and polls, we need to
take the AioContext lock where it is missing, for the only reason that
internally co_wrapper calls AIO_WAIT_WHILE and it expects to release the
AioContext lock.

This is especially messy when a co_wrapper creates a coroutine and polls
in bdrv_open_driver, because this function has so many callers in so
many context that it can easily lead to deadlocks. Therefore the new
rule for bdrv_open_driver is that the caller must always hold the
AioContext lock of the given bs (except if it is a coroutine), because
the function calls bdrv_refresh_total_sectors() which is now a
co_wrapper.

Once the rwlock is ultimated and placed in every place it needs to be,
we will poll using AIO_WAIT_WHILE_UNLOCKED and remove the AioContext
lock.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230113204212.359076-7-kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Emanuele Giuseppe Esposito 2023-01-13 21:42:04 +01:00 • committed by Kevin Wolf
parent c057960c4e
commit c86422c554
35 changed files with 161 additions and 121 deletions
Download patch file Download diff file Expand all files Collapse all files

8
block/quorum.c
View file

@ -754,19 +754,19 @@ static int coroutine_fn quorum_co_pwrite_zeroes(BlockDriverState *bs,
flags | BDRV_REQ_ZERO_WRITE);
}
static int64_t quorum_getlength(BlockDriverState *bs)
static int64_t coroutine_fn quorum_co_getlength(BlockDriverState *bs)
{
BDRVQuorumState *s = bs->opaque;
int64_t result;
int i;
/* check that all file have the same length */
result = bdrv_getlength(s->children[0]->bs);
result = bdrv_co_getlength(s->children[0]->bs);
if (result < 0) {
return result;
}
for (i = 1; i < s->num_children; i++) {
int64_t value = bdrv_getlength(s->children[i]->bs);
int64_t value = bdrv_co_getlength(s->children[i]->bs);
if (value < 0) {
return value;
}
@ -1283,7 +1283,7 @@ static BlockDriver bdrv_quorum = {
.bdrv_co_flush = quorum_co_flush,
.bdrv_getlength = quorum_getlength,
.bdrv_co_getlength = quorum_co_getlength,
.bdrv_co_preadv = quorum_co_preadv,
.bdrv_co_pwritev = quorum_co_pwritev,