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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/crypto.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/crypto.c')
| -rw-r--r-- | block/crypto.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/block/crypto.c b/block/crypto.c index aaa8fb7..210c80d 100644 --- a/block/crypto.c +++ b/block/crypto.c @@ -357,8 +357,9 @@ static int block_crypto_co_create_generic(BlockDriverState *bs, return ret; } -static int block_crypto_truncate(BlockDriverState *bs, int64_t offset, - PreallocMode prealloc, Error **errp) +static int coroutine_fn +block_crypto_co_truncate(BlockDriverState *bs, int64_t offset, + PreallocMode prealloc, Error **errp) { BlockCrypto *crypto = bs->opaque; uint64_t payload_offset = @@ -371,7 +372,7 @@ static int block_crypto_truncate(BlockDriverState *bs, int64_t offset, offset += payload_offset; - return bdrv_truncate(bs->file, offset, prealloc, errp); + return bdrv_co_truncate(bs->file, offset, prealloc, errp); } static void block_crypto_close(BlockDriverState *bs) @@ -700,7 +701,7 @@ BlockDriver bdrv_crypto_luks = { .bdrv_child_perm = bdrv_format_default_perms, .bdrv_co_create = block_crypto_co_create_luks, .bdrv_co_create_opts = block_crypto_co_create_opts_luks, - .bdrv_truncate = block_crypto_truncate, + .bdrv_co_truncate = block_crypto_co_truncate, .create_opts = &block_crypto_create_opts_luks, .bdrv_reopen_prepare = block_crypto_reopen_prepare, |