Re: [PATCH v11 1/5] fs: add iput_if_not_last() helper

["Zhou, Yun" <yun.zhou@windriver.com>]

Hi Honza,

On 6/30/2026 7:34 PM, Jan Kara wrote:
> On Tue 30-06-26 11:05:50, Mateusz Guzik wrote:
>> On Mon, Jun 29, 2026 at 07:08:44PM +0800, Yun Zhou wrote:
>>> Unlike iput_not_last() which BUG_ON's if called with the last ref,
>>> this variant is designed to be called speculatively.
>>>
>>> Signed-off-by: Yun Zhou <yun.zhou@windriver.com>
>>> Suggested-by: Jan Kara <jack@suse.cz>
>>> Reviewed-by: Jan Kara <jack@suse.cz>
>>> ---
>>>   include/linux/fs.h | 13 +++++++++++++
>>>   1 file changed, 13 insertions(+)
>>>
>>> diff --git a/include/linux/fs.h b/include/linux/fs.h
>>> index d10897b3a1e3..04f0de78fa7a 100644
>>> --- a/include/linux/fs.h
>>> +++ b/include/linux/fs.h
>>> @@ -2413,6 +2413,19 @@ static inline void super_set_sysfs_name_generic(struct super_block *sb, const ch
>>>   extern void ihold(struct inode * inode);
>>>   extern void iput(struct inode *);
>>>   void iput_not_last(struct inode *);
>>> +
>>> +/**
>>> + * iput_if_not_last - drop an inode reference only if it is not the last one
>>> + * @inode: inode to put
>>> + *
>>> + * Returns true if the reference was dropped, false if this was the last
>>> + * reference and the caller must arrange for final iput() in a safe context.
>>> + */
>>> +static inline bool __must_check iput_if_not_last(struct inode *inode)
>>> +{
>>> +   return atomic_add_unless(&inode->i_count, -1, 1);
>>> +}
>>> +
>>
>> This still could assert on the count, for example:
>>        VFS_BUG_ON_INODE(inode_state_read_once(inode) & (I_FREEING | I_CLEAR), inode);
>>        VFS_BUG_ON_INODE(atomic_read(&inode->i_count) < 1, inode);
> 
> Yes, it makes sense to be consistent with other helpers. Thanks for the
> idea.

Should I wait for now, or go ahead and include the two macros mentioned
above in v13 as Mateusz suggested? As you know, the v12 series has been 
fully reviewed [1] , and I'm wondering if making this change now might 
cause any inconvenience to everyone.

[1] 
https://lore.kernel.org/linux-ext4/20260630100829.1257618-1-yun.zhou@windriver.com/T/#t