From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Vladimir Sementsov-Ogievskiy Date: Thu, 11 Apr 2024 11:29:23 +0200 Subject: [PATCH] block/copy-before-write: support unligned snapshot-discard 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 Signed-off-by: Fiona Ebner Signed-off-by: Thomas Lamprecht --- block/copy-before-write.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/block/copy-before-write.c b/block/copy-before-write.c index dbdbbca44e..2cbf6f9346 100644 --- a/block/copy-before-write.c +++ b/block/copy-before-write.c @@ -325,14 +325,24 @@ static int coroutine_fn GRAPH_RDLOCK cbw_co_pdiscard_snapshot(BlockDriverState *bs, int64_t offset, int64_t bytes) { 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) { - 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)