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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/sheepdog.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/sheepdog.c')
| -rw-r--r-- | block/sheepdog.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/block/sheepdog.c b/block/sheepdog.c index 665b176..b229a66 100644 --- a/block/sheepdog.c +++ b/block/sheepdog.c @@ -2292,8 +2292,8 @@ static int64_t sd_getlength(BlockDriverState *bs) return s->inode.vdi_size; } -static int sd_truncate(BlockDriverState *bs, int64_t offset, - PreallocMode prealloc, Error **errp) +static int coroutine_fn sd_co_truncate(BlockDriverState *bs, int64_t offset, + PreallocMode prealloc, Error **errp) { BDRVSheepdogState *s = bs->opaque; int ret, fd; @@ -2609,7 +2609,7 @@ static coroutine_fn int sd_co_writev(BlockDriverState *bs, int64_t sector_num, assert(!flags); if (offset > s->inode.vdi_size) { - ret = sd_truncate(bs, offset, PREALLOC_MODE_OFF, NULL); + ret = sd_co_truncate(bs, offset, PREALLOC_MODE_OFF, NULL); if (ret < 0) { return ret; } @@ -3231,7 +3231,7 @@ static BlockDriver bdrv_sheepdog = { .bdrv_has_zero_init = bdrv_has_zero_init_1, .bdrv_getlength = sd_getlength, .bdrv_get_allocated_file_size = sd_get_allocated_file_size, - .bdrv_truncate = sd_truncate, + .bdrv_co_truncate = sd_co_truncate, .bdrv_co_readv = sd_co_readv, .bdrv_co_writev = sd_co_writev, @@ -3268,7 +3268,7 @@ static BlockDriver bdrv_sheepdog_tcp = { .bdrv_has_zero_init = bdrv_has_zero_init_1, .bdrv_getlength = sd_getlength, .bdrv_get_allocated_file_size = sd_get_allocated_file_size, - .bdrv_truncate = sd_truncate, + .bdrv_co_truncate = sd_co_truncate, .bdrv_co_readv = sd_co_readv, .bdrv_co_writev = sd_co_writev, @@ -3305,7 +3305,7 @@ static BlockDriver bdrv_sheepdog_unix = { .bdrv_has_zero_init = bdrv_has_zero_init_1, .bdrv_getlength = sd_getlength, .bdrv_get_allocated_file_size = sd_get_allocated_file_size, - .bdrv_truncate = sd_truncate, + .bdrv_co_truncate = sd_co_truncate, .bdrv_co_readv = sd_co_readv, .bdrv_co_writev = sd_co_writev, |