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

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

Hi Honza,

On 7/2/2026 10:29 PM, Jan Kara wrote:
> 
> Hi!
> 
> On Thu 02-07-26 21:35:47, Zhou, Yun wrote:
>> 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
> 
> I think there will be no more feedback to this series. So just include this
> suggested change (keeping current Reviewed-by tags - the change is minimal)
> and submit one more version. Mention in the cover letter that there's only
> minor adjustment to this one patch, everything is reviewed and ready to be
> merged so that Ted knows.
> 
>                                                                  Honza
> --
> Jan Kara <jack@suse.com>
> SUSE Labs, CR

Okay, I'll get right on it. Thank you very much for your reply and your 
strong support on this patch series.

BR,
Yun