Re: [PATCH] ext4: Fix ERR_PTR(0) in ext4_mkdir()

[Hongling Zeng <zhongling0719@126.com>]

   Hi ,

   Good point! I've been systematically fixing this across filesystems.
   Several fixes have already been merged (9p, jfs, orangefs,cachefiles....)

   Still working on a few more filesystems.

   Thanks for the suggestion!

   Best regards,
   Hongling

在 2026年05月20日 17:19, Zhang Yi 写道:
> On 5/20/2026 3:46 PM, Hongling Zeng wrote:
>> When mkdir succeeds, ext4_mkdir() returns ERR_PTR(0) which is incorrect.
>> It should return NULL instead for success and ERR_PTR() only with
>> negative error codes for failure.
> This point is indeed very easy to overlook. However, why not modify
> other file systems as well? Commit 88d5baf69082 made changes not only
> to ext4.
>
> Thanks,
> Yi.
>
>> Fixes: 88d5baf69082 ("Change inode_operations.mkdir to return struct dentry *")
>> Signed-off-by: Hongling Zeng <zenghongling@kylinos.cn>
>> ---
>>   fs/ext4/namei.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
>> index 4a47fbd8dd30..8cadaeb15b2b 100644
>> --- a/fs/ext4/namei.c
>> +++ b/fs/ext4/namei.c
>> @@ -3054,7 +3054,7 @@ static struct dentry *ext4_mkdir(struct mnt_idmap *idmap, struct inode *dir,
>>   out_retry:
>>   	if (err == -ENOSPC && ext4_should_retry_alloc(dir->i_sb, &retries))
>>   		goto retry;
>> -	return ERR_PTR(err);
>> +	return err ? ERR_PTR(err) : NULL;
>>   }
>>   
>>   /*