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block: Convert bdrv_refresh_total_sectors() to co_wrapper_mixed

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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

12
block/gluster.c
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@ -1318,7 +1318,7 @@ static coroutine_fn int qemu_gluster_co_pdiscard(BlockDriverState *bs,
}
#endif
static int64_t qemu_gluster_getlength(BlockDriverState *bs)
static int64_t coroutine_fn qemu_gluster_co_getlength(BlockDriverState *bs)
{
BDRVGlusterState *s = bs->opaque;
int64_t ret;
@ -1510,7 +1510,7 @@ static int coroutine_fn qemu_gluster_co_block_status(BlockDriverState *bs,
* round up if necessary.
*/
if (!QEMU_IS_ALIGNED(*pnum, bs->bl.request_alignment)) {
int64_t file_length = qemu_gluster_getlength(bs);
int64_t file_length = qemu_gluster_co_getlength(bs);
if (file_length > 0) {
/* Ignore errors, this is just a safeguard */
assert(hole == file_length);
@ -1559,7 +1559,7 @@ static BlockDriver bdrv_gluster = {
.bdrv_close = qemu_gluster_close,
.bdrv_co_create = qemu_gluster_co_create,
.bdrv_co_create_opts = qemu_gluster_co_create_opts,
.bdrv_getlength = qemu_gluster_getlength,
.bdrv_co_getlength = qemu_gluster_co_getlength,
.bdrv_get_allocated_file_size = qemu_gluster_allocated_file_size,
.bdrv_co_truncate = qemu_gluster_co_truncate,
.bdrv_co_readv = qemu_gluster_co_readv,
@ -1588,7 +1588,7 @@ static BlockDriver bdrv_gluster_tcp = {
.bdrv_close = qemu_gluster_close,
.bdrv_co_create = qemu_gluster_co_create,
.bdrv_co_create_opts = qemu_gluster_co_create_opts,
.bdrv_getlength = qemu_gluster_getlength,
.bdrv_co_getlength = qemu_gluster_co_getlength,
.bdrv_get_allocated_file_size = qemu_gluster_allocated_file_size,
.bdrv_co_truncate = qemu_gluster_co_truncate,
.bdrv_co_readv = qemu_gluster_co_readv,
@ -1617,7 +1617,7 @@ static BlockDriver bdrv_gluster_unix = {
.bdrv_close = qemu_gluster_close,
.bdrv_co_create = qemu_gluster_co_create,
.bdrv_co_create_opts = qemu_gluster_co_create_opts,
.bdrv_getlength = qemu_gluster_getlength,
.bdrv_co_getlength = qemu_gluster_co_getlength,
.bdrv_get_allocated_file_size = qemu_gluster_allocated_file_size,
.bdrv_co_truncate = qemu_gluster_co_truncate,
.bdrv_co_readv = qemu_gluster_co_readv,
@ -1652,7 +1652,7 @@ static BlockDriver bdrv_gluster_rdma = {
.bdrv_close = qemu_gluster_close,
.bdrv_co_create = qemu_gluster_co_create,
.bdrv_co_create_opts = qemu_gluster_co_create_opts,
.bdrv_getlength = qemu_gluster_getlength,
.bdrv_co_getlength = qemu_gluster_co_getlength,
.bdrv_get_allocated_file_size = qemu_gluster_allocated_file_size,
.bdrv_co_truncate = qemu_gluster_co_truncate,
.bdrv_co_readv = qemu_gluster_co_readv,