diff options
| author | Kevin Wolf <kwolf@redhat.com> | 2018-06-21 17:54:35 +0200 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2018-06-29 14:20:56 +0200 |
| commit | 061ca8a368165fae300748c17971824a089f521f (patch) | |
| tree | 94e2fb34999021ead20698bf7399ae151d13047b /block/nfs.c | |
| parent | ae5475e82fd1ebb24f4f77cf28f59ca6548c6136 (diff) | |
block: Convert .bdrv_truncate callback to coroutine_fn
bdrv_truncate() is an operation that can block (even for a quite long
time, depending on the PreallocMode) in I/O paths that shouldn't block.
Convert it to a coroutine_fn so that we have the infrastructure for
drivers to make their .bdrv_co_truncate implementation asynchronous.
This change could potentially introduce new race conditions because
bdrv_truncate() isn't necessarily executed atomically any more. Whether
this is a problem needs to be evaluated for each block driver that
supports truncate:
* file-posix/win32, gluster, iscsi, nfs, rbd, ssh, sheepdog: The
protocol drivers are trivially safe because they don't actually yield
yet, so there is no change in behaviour.
* copy-on-read, crypto, raw-format: Essentially just filter drivers that
pass the request to a child node, no problem.
* qcow2: The implementation modifies metadata, so it needs to hold
s->lock to be safe with concurrent I/O requests. In order to avoid
double locking, this requires pulling the locking out into
preallocate_co() and using qcow2_write_caches() instead of
bdrv_flush().
* qed: Does a single header update, this is fine without locking.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'block/nfs.c')
| -rw-r--r-- | block/nfs.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/block/nfs.c b/block/nfs.c index 743ca0450e..eab1a2c408 100644 --- a/block/nfs.c +++ b/block/nfs.c @@ -743,8 +743,9 @@ static int64_t nfs_get_allocated_file_size(BlockDriverState *bs) return (task.ret < 0 ? task.ret : st.st_blocks * 512); } -static int nfs_file_truncate(BlockDriverState *bs, int64_t offset, - PreallocMode prealloc, Error **errp) +static int coroutine_fn +nfs_file_co_truncate(BlockDriverState *bs, int64_t offset, + PreallocMode prealloc, Error **errp) { NFSClient *client = bs->opaque; int ret; @@ -873,7 +874,7 @@ static BlockDriver bdrv_nfs = { .bdrv_has_zero_init = nfs_has_zero_init, .bdrv_get_allocated_file_size = nfs_get_allocated_file_size, - .bdrv_truncate = nfs_file_truncate, + .bdrv_co_truncate = nfs_file_co_truncate, .bdrv_file_open = nfs_file_open, .bdrv_close = nfs_file_close, |