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

[Hongling Zeng <zhongling0719@126.com>]

在 2026年08月17日 14:43, Qu Wenruo 写道:
>
>
> 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 
>
>
   Thanks for the feedback.

   I should have checked for existing fixes first.

   I will ensure to check git history and mailing lists before submitting
   future patches.

   Apologies for the duplicate submission.
>> ---
>>   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);
>>       }