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authorChristoph Hellwig <hch@lst.de>2023-07-24 17:22:38 +0300
committerDavid Sterba <dsterba@suse.com>2023-08-21 15:54:47 +0300
commit953fa5ced510c4937075002bbfc6405cd500efef (patch)
tree1fdd31a5cd29a45ae2c15e0f63c62054d5717e3d
parent332581bde2a419d5f12a93a1cdc2856af649a3cc (diff)
downloadlinux-953fa5ced510c4937075002bbfc6405cd500efef.tar.xz
btrfs: fix error handling when in a COW window in run_delalloc_nocow
When run_delalloc_nocow has cow_start set to a value other than (u64)-1, it has delayed COW writeback pending behind cur_offset. When an error occurs in such a window, the range going back to cow_start and not just cur_offset needs to be unlocked, but only two error cases handle this correctly Move the code to handle unlock the COW range to the common error handling label and document the logic. To make things even more complicated, cow_file_range as called by fallback_to_cow will unlock the range it is operating on when it fails as well, so we need to reset cow_start right after caling fallback_to_cow instead of only when it succeeded. Reviewed-by: Boris Burkov <boris@bur.io> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: David Sterba <dsterba@suse.com>
-rw-r--r--fs/btrfs/inode.c22
1 files changed, 12 insertions, 10 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index f2ab27084cc4..0d973a959559 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2029,11 +2029,8 @@ next_slot:
leaf = path->nodes[0];
if (path->slots[0] >= btrfs_header_nritems(leaf)) {
ret = btrfs_next_leaf(root, path);
- if (ret < 0) {
- if (cow_start != (u64)-1)
- cur_offset = cow_start;
+ if (ret < 0)
goto error;
- }
if (ret > 0)
break;
leaf = path->nodes[0];
@@ -2096,13 +2093,10 @@ next_slot:
nocow_args.start = cur_offset;
ret = can_nocow_file_extent(path, &found_key, inode, &nocow_args);
- if (ret < 0) {
- if (cow_start != (u64)-1)
- cur_offset = cow_start;
+ if (ret < 0)
goto error;
- } else if (ret == 0) {
+ if (ret == 0)
goto out_check;
- }
ret = 0;
bg = btrfs_inc_nocow_writers(fs_info, nocow_args.disk_bytenr);
@@ -2133,9 +2127,9 @@ out_check:
if (cow_start != (u64)-1) {
ret = fallback_to_cow(inode, locked_page,
cow_start, found_key.offset - 1);
+ cow_start = (u64)-1;
if (ret)
goto error;
- cow_start = (u64)-1;
}
nocow_end = cur_offset + nocow_args.num_bytes - 1;
@@ -2214,6 +2208,7 @@ out_check:
if (cow_start != (u64)-1) {
cur_offset = end;
ret = fallback_to_cow(inode, locked_page, cow_start, end);
+ cow_start = (u64)-1;
if (ret)
goto error;
}
@@ -2222,6 +2217,13 @@ error:
if (nocow)
btrfs_dec_nocow_writers(bg);
+ /*
+ * If an error happened while a COW region is outstanding, cur_offset
+ * needs to be reset to cow_start to ensure the COW region is unlocked
+ * as well.
+ */
+ if (cow_start != (u64)-1)
+ cur_offset = cow_start;
if (ret && cur_offset < end)
extent_clear_unlock_delalloc(inode, cur_offset, end,
locked_page, EXTENT_LOCKED |