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| 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/rbd.c | |
| parent | ae5475e82fd1ebb24f4f77cf28f59ca6548c6136 (diff) | |
| download | qemu-061ca8a368165fae300748c17971824a089f521f.zip qemu-061ca8a368165fae300748c17971824a089f521f.tar.gz qemu-061ca8a368165fae300748c17971824a089f521f.tar.bz2 | |
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/rbd.c')
| -rw-r--r-- | block/rbd.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/block/rbd.c b/block/rbd.c index f2c6965..ca8e5bb 100644 --- a/block/rbd.c +++ b/block/rbd.c @@ -990,8 +990,10 @@ static int64_t qemu_rbd_getlength(BlockDriverState *bs) return info.size; } -static int qemu_rbd_truncate(BlockDriverState *bs, int64_t offset, - PreallocMode prealloc, Error **errp) +static int coroutine_fn qemu_rbd_co_truncate(BlockDriverState *bs, + int64_t offset, + PreallocMode prealloc, + Error **errp) { BDRVRBDState *s = bs->opaque; int r; @@ -1184,7 +1186,7 @@ static BlockDriver bdrv_rbd = { .bdrv_get_info = qemu_rbd_getinfo, .create_opts = &qemu_rbd_create_opts, .bdrv_getlength = qemu_rbd_getlength, - .bdrv_truncate = qemu_rbd_truncate, + .bdrv_co_truncate = qemu_rbd_co_truncate, .protocol_name = "rbd", .bdrv_aio_preadv = qemu_rbd_aio_preadv, |