Re: [PATCH] btrfs: fix missing folio_unlock in read_merkle_tree_page error path

[Qu Wenruo <wqu@suse.com>]

在 2026/8/17 15:06, Hongling Zeng 写道:
> filemap_add_folio() adds the folio to the page cache and leaves it locked.
> If read_key_bytes() fails, the error path only calls folio_put() without
> first unlocking the folio, leaving it permanently locked in the page cache.
> This causes subsequent attempts to lock this folio to hang.
> 
> Fix by adding folio_unlock() before folio_put() in the error handling path.
> 
> Fixes: 06ed09351b67 ("btrfs: convert btrfs_read_merkle_tree_page() to use a folio")
> Cc: stable@vger.kernel.org
> Assisted-by: Codex:gpt-5.5
> Signed-off-by: Hongling Zeng <zenghongling@kylinos.cn>

A fix is already submitted and merged:

https://lore.kernel.org/linux-btrfs/20260722025435.1493093-1-chenyichong@uniontech.com/

Next time let your agent to read the btrfs developer's note and check if 
there is already a fix:

https://btrfs.readthedocs.io/en/latest/dev/Developer-s-FAQ.html#development-phase-linux-next-for-next

> ---
>   fs/btrfs/verity.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/fs/btrfs/verity.c b/fs/btrfs/verity.c
> index 983365a73541..4431656140f8 100644
> --- a/fs/btrfs/verity.c
> +++ b/fs/btrfs/verity.c
> @@ -753,6 +753,7 @@ static struct page *btrfs_read_merkle_tree_page(struct inode *inode,
>   	ret = read_key_bytes(BTRFS_I(inode), BTRFS_VERITY_MERKLE_ITEM_KEY, off,
>   			     folio_address(folio), PAGE_SIZE, folio);
>   	if (ret < 0) {
> +		folio_unlock(folio);
>   		folio_put(folio);
>   		return ERR_PTR(ret);
>   	}