debian/patches/pve/0047-block-copy-before-write-support-unligned-snapshot-di.patch

   1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
   2 From: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
   3 Date: Thu, 11 Apr 2024 11:29:23 +0200
   4 Subject: [PATCH] block/copy-before-write: support unligned snapshot-discard
   5
   6 First thing that crashes on unligned access here is
   7 bdrv_reset_dirty_bitmap(). Correct way is to align-down the
   8 snapshot-discard request.
   9
  10 Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
  11 Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
  12 Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
  13 ---
  14  block/copy-before-write.c | 16 +++++++++++++---
  15  1 file changed, 13 insertions(+), 3 deletions(-)
  16
  17 diff --git a/block/copy-before-write.c b/block/copy-before-write.c
  18 index a2dddf6f57..0a219c2b75 100644
  19 --- a/block/copy-before-write.c
  20 +++ b/block/copy-before-write.c
  21 @@ -325,14 +325,24 @@ static int coroutine_fn GRAPH_RDLOCK
  22  cbw_co_pdiscard_snapshot(BlockDriverState *bs, int64_t offset, int64_t bytes)
  23  {
  24      BDRVCopyBeforeWriteState *s = bs->opaque;
  25 +    uint32_t cluster_size = block_copy_cluster_size(s->bcs);
  26 +    int64_t aligned_offset = QEMU_ALIGN_UP(offset, cluster_size);
  27 +    int64_t aligned_end = QEMU_ALIGN_DOWN(offset + bytes, cluster_size);
  28 +    int64_t aligned_bytes;
  29 +
  30 +    if (aligned_end <= aligned_offset) {
  31 +        return 0;
  32 +    }
  33 +    aligned_bytes = aligned_end - aligned_offset;
  34
  35      WITH_QEMU_LOCK_GUARD(&s->lock) {
  36 -        bdrv_reset_dirty_bitmap(s->access_bitmap, offset, bytes);
  37 +        bdrv_reset_dirty_bitmap(s->access_bitmap, aligned_offset,
  38 +                                aligned_bytes);
  39      }
  40
  41 -    block_copy_reset(s->bcs, offset, bytes);
  42 +    block_copy_reset(s->bcs, aligned_offset, aligned_bytes);
  43
  44 -    return bdrv_co_pdiscard(s->target, offset, bytes);
  45 +    return bdrv_co_pdiscard(s->target, aligned_offset, aligned_bytes);
  46  }
  47
  48  static void cbw_refresh_filename(BlockDriverState *bs)