Re: [RFC PATCH] filelock: new helper: vfs_file_has_locks

[Xiubo Li <xiubli@redhat.com>]

On 16/11/2022 19:25, Jeff Layton wrote:
> On Wed, 2022-11-16 at 19:16 +0800, Xiubo Li wrote:
>> On 16/11/2022 18:55, Jeff Layton wrote:
>>> On Wed, 2022-11-16 at 14:49 +0800, Xiubo Li wrote:
>>>> On 15/11/2022 22:40, Jeff Layton wrote:
>>>>
>> ...
>>>>> +	spin_lock(&ctx->flc_lock);
>>>>> +	ret = !list_empty(&ctx->flc_posix) || !list_empty(&ctx->flc_flock);
>>>>> +	spin_unlock(&ctx->flc_lock);
>>>> BTW, is the spin_lock/spin_unlock here really needed ?
>>>>
>>> We could probably achieve the same effect with barriers, but I doubt
>>> it's worth it. The flc_lock only protects the lists in the
>>> file_lock_context, so it should almost always be uncontended.
>>>
>> I just see some other places where are also checking this don't use the
>> spin lock.
>>
>>
> True.
>
> There are a number of places that don't and that use list_empty_careful.
> Some of those  We could convert to that here, but again, I'm not sure
> it's worth it. Let's stick with using the spinlocks here, since this
> isn't a performance-critical codepath anyway.
>
Okay.

Thanks!


>>>>> +	return ret;
>>>>> +}
>>>>> +EXPORT_SYMBOL_GPL(vfs_inode_has_locks);
>>>>> +
>>>>>     #ifdef CONFIG_PROC_FS
>>>>>     #include <linux/proc_fs.h>
>>>>>     #include <linux/seq_file.h>
>>>>> diff --git a/include/linux/fs.h b/include/linux/fs.h
>>>>> index e654435f1651..d6cb42b7e91c 100644
>>>>> --- a/include/linux/fs.h
>>>>> +++ b/include/linux/fs.h
>>>>> @@ -1170,6 +1170,7 @@ extern int locks_delete_block(struct file_lock *);
>>>>>     extern int vfs_test_lock(struct file *, struct file_lock *);
>>>>>     extern int vfs_lock_file(struct file *, unsigned int, struct file_lock *, struct file_lock *);
>>>>>     extern int vfs_cancel_lock(struct file *filp, struct file_lock *fl);
>>>>> +bool vfs_inode_has_locks(struct inode *inode);
>>>>>     extern int locks_lock_inode_wait(struct inode *inode, struct file_lock *fl);
>>>>>     extern int __break_lease(struct inode *inode, unsigned int flags, unsigned int type);
>>>>>     extern void lease_get_mtime(struct inode *, struct timespec64 *time);
>>>> All the others LGTM.
>>>>
>>>> Thanks.
>>>>
>>>> - Xiubo
>>>>
>>>>
>>> Thanks. I'll re-post it "officially" in a bit and will queue it up for
>>> v6.2.