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

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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.




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