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authorAndrey Drobyshev <andrey.drobyshev@virtuozzo.com>2023-07-11 20:25:52 +0300
committerStefan Hajnoczi <stefanha@redhat.com>2023-08-30 07:39:10 -0400
commitfc6b211f920a68f4c9c8db91ccc35ca95fe6683a (patch)
tree6a7fb31cd09918d1580f3638614846dca146e182 /include
parentc54483b6f45a0c84e230728a1a9e7adf90345e15 (diff)
downloadfocaccia-qemu-fc6b211f920a68f4c9c8db91ccc35ca95fe6683a.tar.gz
focaccia-qemu-fc6b211f920a68f4c9c8db91ccc35ca95fe6683a.zip
block/io: align requests to subcluster_size
When target image is using subclusters, and we align the request during
copy-on-read, it makes sense to align to subcluster_size rather than
cluster_size.  Otherwise we end up with unnecessary allocations.

This commit renames bdrv_round_to_clusters() to bdrv_round_to_subclusters()
and utilizes subcluster_size field of BlockDriverInfo to make necessary
alignments.  It affects copy-on-read as well as mirror job (which is
using bdrv_round_to_clusters()).

This change also fixes the following bug with failing assert (covered by
the test in the subsequent commit):

qemu-img create -f qcow2 base.qcow2 64K
qemu-img create -f qcow2 -o extended_l2=on,backing_file=base.qcow2,backing_fmt=qcow2 img.qcow2 64K
qemu-io -c "write -P 0xaa 0 2K" img.qcow2
qemu-io -C -c "read -P 0x00 2K 62K" img.qcow2

qemu-io: ../block/io.c:1236: bdrv_co_do_copy_on_readv: Assertion `skip_bytes < pnum' failed.

Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230711172553.234055-3-andrey.drobyshev@virtuozzo.com>
Diffstat (limited to 'include')
-rw-r--r--include/block/block-io.h8
1 files changed, 4 insertions, 4 deletions
diff --git a/include/block/block-io.h b/include/block/block-io.h
index 4415506e40..6db48f2d35 100644
--- a/include/block/block-io.h
+++ b/include/block/block-io.h
@@ -189,10 +189,10 @@ bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi);
 ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs,
                                           Error **errp);
 BlockStatsSpecific *bdrv_get_specific_stats(BlockDriverState *bs);
-void bdrv_round_to_clusters(BlockDriverState *bs,
-                            int64_t offset, int64_t bytes,
-                            int64_t *cluster_offset,
-                            int64_t *cluster_bytes);
+void bdrv_round_to_subclusters(BlockDriverState *bs,
+                               int64_t offset, int64_t bytes,
+                               int64_t *cluster_offset,
+                               int64_t *cluster_bytes);
 
 void bdrv_get_backing_filename(BlockDriverState *bs,
                                char *filename, int filename_size);