Hi,

From: Filipe Manana fdmanana@suse.com

When using the logical to ino ioctl v2, if the flag to ignore offsets of file extent items (BTRFS_LOGICAL_INO_ARGS_IGNORE_OFFSET) is given, the backref walking code ends up not returning references for all file offsets of an inode that point to the given logical bytenr. This happens since kernel 6.2, commit 6ce6ba534418 ("btrfs: use a single argument for extent offset in backref walking functions"), as it mistakenly skipped the search for file extent items in a leaf that point to the target extent if that flag is given. Instead it should only skip the filtering done by check_extent_in_eb() - that is, it should not avoid the calls to that function.

So fix this by always calling check_extent_in_eb() and have this function do the filtering only if an extent offset is given and the flag to ignore offsets is not set. Fixes: 6ce6ba534418 ("btrfs: use a single argument for extent offset in backref walking functions") Reported-by: Vladimir Panteleev git@vladimir.panteleev.md Link: https://lore.kernel.org/linux-btrfs/CAHhfkvwo=nmzrJSqZ2qMfF-rZB-ab6ahHnCD_sq... Tested-by: Vladimir Panteleev git@vladimir.panteleev.md CC: stable@vger.kernel.org # 6.2+ Signed-off-by: Filipe Manana fdmanana@suse.com

fstests(btrfs/299) will fail with this patch.

Best Regards Wang Yugui (wangyugui@e16-tech.com) 2023/05/04

---

fs/btrfs/backref.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c index e54f0884802a..8e61be3fe9a8 100644 --- a/fs/btrfs/backref.c +++ b/fs/btrfs/backref.c @@ -45,7 +45,9 @@ static int check_extent_in_eb(struct btrfs_backref_walk_ctx *ctx, int root_count; bool cached;

• if (!btrfs_file_extent_compression(eb, fi) &&

• if (!ctx->ignore_extent_item_pos &&

•    ctx->extent_item_pos > 0 &&
  

•    !btrfs_file_extent_compression(eb, fi) &&
   !btrfs_file_extent_encryption(eb, fi) &&
   !btrfs_file_extent_other_encoding(eb, fi)) {
  

  u64 data_offset;

@@ -552,13 +554,10 @@ static int add_all_parents(struct btrfs_backref_walk_ctx *ctx, count++; else goto next;

• 	if (!ctx->ignore_extent_item_pos) {
  

• 		ret = check_extent_in_eb(ctx, &key, eb, fi, &eie);
  

• 		if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP ||
  

• 		    ret < 0)
  

• 			break;
  

• 	}
  

• 	if (ret > 0)
  

• 	ret = check_extent_in_eb(ctx, &key, eb, fi, &eie);
  

• 	if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP || ret < 0)
  

• 		break;
  

• 	else if (ret > 0)
  	goto next;
  ret = ulist_add_merge_ptr(parents, eb->start,
  			  eie, (void **)&old, GFP_NOFS);
  

-- 2.35.1

From: Filipe Manana fdmanana@suse.com

When using the logical to ino ioctl v2, if the flag to ignore offsets of file extent items (BTRFS_LOGICAL_INO_ARGS_IGNORE_OFFSET) is given, the backref walking code ends up not returning references for all file offsets of an inode that point to the given logical bytenr. This happens since kernel 6.2, commit 6ce6ba534418 ("btrfs: use a single argument for extent offset in backref walking functions"), as it mistakenly skipped the search for file extent items in a leaf that point to the target extent if that flag is given. Instead it should only skip the filtering done by check_extent_in_eb() - that is, it should not avoid the calls to that function (or find_extent_in_eb(), which uses it).

So fix this by always calling check_extent_in_eb() and find_extent_in_eb() and have check_extent_in_eb() do the filtering only if the flag to ignore offsets is set.

Fixes: 6ce6ba534418 ("btrfs: use a single argument for extent offset in backref walking functions") Reported-by: Vladimir Panteleev git@vladimir.panteleev.md Link: https://lore.kernel.org/linux-btrfs/CAHhfkvwo=nmzrJSqZ2qMfF-rZB-ab6ahHnCD_sq... Tested-by: Vladimir Panteleev git@vladimir.panteleev.md CC: stable@vger.kernel.org # 6.2+ Signed-off-by: Filipe Manana fdmanana@suse.com ---

V2: Remove wrong check for a non-zero extent item offset. Apply the same logic at find_parent_nodes(), that is, search for file extent items on a leaf if the ignore flag is given - the filtering will be done later at check_extent_in_eb(). Spotted by Vladimir Panteleev in the thread mentioned above.

fs/btrfs/backref.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c index e54f0884802a..787417f9893c 100644 --- a/fs/btrfs/backref.c +++ b/fs/btrfs/backref.c @@ -45,7 +45,8 @@ static int check_extent_in_eb(struct btrfs_backref_walk_ctx *ctx, int root_count; bool cached;

- if (!btrfs_file_extent_compression(eb, fi) && + if (!ctx->ignore_extent_item_pos && + !btrfs_file_extent_compression(eb, fi) && !btrfs_file_extent_encryption(eb, fi) && !btrfs_file_extent_other_encoding(eb, fi)) { u64 data_offset; @@ -552,13 +553,10 @@ static int add_all_parents(struct btrfs_backref_walk_ctx *ctx, count++; else goto next; - if (!ctx->ignore_extent_item_pos) { - ret = check_extent_in_eb(ctx, &key, eb, fi, &eie); - if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP || - ret < 0) - break; - } - if (ret > 0) + ret = check_extent_in_eb(ctx, &key, eb, fi, &eie); + if (ret == BTRFS_ITERATE_EXTENT_INODES_STOP || ret < 0) + break; + else if (ret > 0) goto next; ret = ulist_add_merge_ptr(parents, eb->start, eie, (void **)&old, GFP_NOFS); @@ -1606,8 +1604,7 @@ static int find_parent_nodes(struct btrfs_backref_walk_ctx *ctx, goto out; } if (ref->count && ref->parent) { - if (!ctx->ignore_extent_item_pos && !ref->inode_list && - ref->level == 0) { + if (!ref->inode_list && ref->level == 0) { struct btrfs_tree_parent_check check = { 0 }; struct extent_buffer *eb;