[PATCH 0/2] btrfs: clean up two FIXMEs related to btrfs_search_slot output handling

[PATCH 0/2] btrfs: clean up two FIXMEs related to btrfs_search_slot output handling

[Adarsh Das]

Both patches fix cases where a search with offset (u64)-1 gets an
unexpected exact match. The first silently returned success, and the
second crashed the kernel. Both now both log an error and return -EUCLEAN.

Adarsh Das (2):
  btrfs: handle unexpected exact match in btrfs_set_inode_index_count()
  btrfs: replace BUG() with error handling in __btrfs_balance()

 fs/btrfs/inode.c   | 15 ++++++++++++---
 fs/btrfs/volumes.c | 10 ++++++++--
 2 files changed, 20 insertions(+), 5 deletions(-)

-- 
2.53.0

[PATCH 1/2] btrfs: handle unexpected exact match in btrfs_set_inode_index_count()

[Adarsh Das]

We search with offset (u64)-1 which should never match exactly.
Previously the code silently returned success without setting the index
count. Now logs an error and return -EUCLEAN instead.

Signed-off-by: Adarsh Das <adarshdas950@gmail.com>
---
 fs/btrfs/inode.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index a2b5b440637e..9f46bfff1e4b 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -6105,9 +6105,18 @@ static int btrfs_set_inode_index_count(struct btrfs_inode *inode)
 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 	if (ret < 0)
 		return ret;
-	/* FIXME: we should be able to handle this */
-	if (ret == 0)
-		return ret;
+
+	if (unlikely(ret == 0)) {
+		/*
+		 * Key with offset -1 found, there would have to exist a dir
+		 * index item with such offset, but this is out of the valid
+		 * range.
+		 */
+		btrfs_err(root->fs_info,
+			  "unexpected exact match for dir index key, inode %llu",
+			  btrfs_ino(inode));
+		return -EUCLEAN;
+	}
 
 	if (path->slots[0] == 0) {
 		inode->index_cnt = BTRFS_DIR_START_INDEX;
-- 
2.53.0

[PATCH 2/2] btrfs: replace BUG() with error handling in __btrfs_balance()

[Adarsh Das]

We search with offset (u64)-1 which should never match exactly.
Previously this was handled with BUG(). Now logs an error
and return -EUCLEAN.

Signed-off-by: Adarsh Das <adarshdas950@gmail.com>
---
 fs/btrfs/volumes.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 8a08412f3529..0e1cc0c4ce68 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4112,8 +4112,14 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
 		 * this shouldn't happen, it means the last relocate
 		 * failed
 		 */
-		if (ret == 0)
-			BUG(); /* FIXME break ? */
+		if (unlikely(ret == 0)) {
+			btrfs_err(fs_info,
+				  "unexpected exact match in chunk tree search, offset 0x%llx",
+				  key.offset);
+			mutex_unlock(&fs_info->reclaim_bgs_lock);
+			ret = -EUCLEAN;
+			goto error;
+		}
 
 		ret = btrfs_previous_item(chunk_root, path, 0,
 					  BTRFS_CHUNK_ITEM_KEY);
-- 
2.53.0

Re: [PATCH 0/2] btrfs: clean up two FIXMEs related to btrfs_search_slot output handling

[Qu Wenruo]

在 2026/2/4 03:53, Adarsh Das 写道:
> Both patches fix cases where a search with offset (u64)-1 gets an
> unexpected exact match. The first silently returned success, and the
> second crashed the kernel. Both now both log an error and return -EUCLEAN.

Reviewed-by: Qu Wenruo <wqu@suse.com>

Thanks,
Qu

> 
> Adarsh Das (2):
>    btrfs: handle unexpected exact match in btrfs_set_inode_index_count()
>    btrfs: replace BUG() with error handling in __btrfs_balance()
> 
>   fs/btrfs/inode.c   | 15 ++++++++++++---
>   fs/btrfs/volumes.c | 10 ++++++++--
>   2 files changed, 20 insertions(+), 5 deletions(-)
> 

Re: [PATCH 0/2] btrfs: clean up two FIXMEs related to btrfs_search_slot output handling

[David Sterba]

On Tue, Feb 03, 2026 at 10:53:55PM +0530, Adarsh Das wrote:
> Both patches fix cases where a search with offset (u64)-1 gets an
> unexpected exact match. The first silently returned success, and the
> second crashed the kernel. Both now both log an error and return -EUCLEAN.
> 
> Adarsh Das (2):
>   btrfs: handle unexpected exact match in btrfs_set_inode_index_count()
>   btrfs: replace BUG() with error handling in __btrfs_balance()

Added to for-next, thanks.