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block/copy-before-write: support unligned snapshot-discard

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First thing that crashes on unligned access here is
bdrv_reset_dirty_bitmap(). Correct way is to align-down the
snapshot-discard request.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Fiona Ebner <f.ebner@proxmox.com>
Tested-by: Fiona Ebner <f.ebner@proxmox.com>
Message-Id: <20240313152822.626493-3-vsementsov@yandex-team.ru>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
This commit is contained in:
Vladimir Sementsov-Ogievskiy 2024-03-13 18:28:19 +03:00
parent 137b4d4bd5
commit 507175197b
1 changed files with 13 additions and 3 deletions
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16
block/copy-before-write.c
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@ -325,14 +325,24 @@ static int coroutine_fn GRAPH_RDLOCK
cbw_co_pdiscard_snapshot(BlockDriverState *bs, int64_t offset, int64_t bytes) cbw_co_pdiscard_snapshot(BlockDriverState *bs, int64_t offset, int64_t bytes)
{ {
BDRVCopyBeforeWriteState *s = bs->opaque; BDRVCopyBeforeWriteState *s = bs->opaque;
uint32_t cluster_size = block_copy_cluster_size(s->bcs);
int64_t aligned_offset = QEMU_ALIGN_UP(offset, cluster_size);
int64_t aligned_end = QEMU_ALIGN_DOWN(offset + bytes, cluster_size);
int64_t aligned_bytes;
if (aligned_end <= aligned_offset) {
return 0;
}
aligned_bytes = aligned_end - aligned_offset;
WITH_QEMU_LOCK_GUARD(&s->lock) { WITH_QEMU_LOCK_GUARD(&s->lock) {
bdrv_reset_dirty_bitmap(s->access_bitmap, offset, bytes); bdrv_reset_dirty_bitmap(s->access_bitmap, aligned_offset,
aligned_bytes);
} }
block_copy_reset(s->bcs, offset, bytes); block_copy_reset(s->bcs, aligned_offset, aligned_bytes);
return bdrv_co_pdiscard(s->target, offset, bytes); return bdrv_co_pdiscard(s->target, aligned_offset, aligned_bytes);
} }
static void GRAPH_RDLOCK cbw_refresh_filename(BlockDriverState *bs) static void GRAPH_RDLOCK cbw_refresh_filename(BlockDriverState *bs)