[PATCH] fs: Drop wait_unfrozen wait queue

[PATCH] fs: Drop wait_unfrozen wait queue

[Jan Kara]

wait_unfrozen waitqueue is used only in quota code to wait for
filesystem to become unfrozen. In that place we can just use
sb_start_write() - sb_end_write() pair to achieve the same. So just
remove the waitqueue.

Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/quota/quota.c   | 5 +++--
 fs/super.c         | 4 ----
 include/linux/fs.h | 1 -
 3 files changed, 3 insertions(+), 7 deletions(-)

Guys, I can merge this cleanup through my tree since I don't expect any
conflicts and the generic part is pure removal of unused code.

diff --git a/fs/quota/quota.c b/fs/quota/quota.c
index 052f143e2e0e..0e41fb84060f 100644
--- a/fs/quota/quota.c
+++ b/fs/quota/quota.c
@@ -895,8 +895,9 @@ static struct super_block *quotactl_block(const char __user *special, int cmd)
 			up_write(&sb->s_umount);
 		else
 			up_read(&sb->s_umount);
-		wait_event(sb->s_writers.wait_unfrozen,
-			   sb->s_writers.frozen == SB_UNFROZEN);
+		/* Wait for sb to unfreeze */
+		sb_start_write(sb);
+		sb_end_write(sb);
 		put_super(sb);
 		goto retry;
 	}
diff --git a/fs/super.c b/fs/super.c
index 34afe411cf2b..6283cea67280 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -236,7 +236,6 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags,
 					&type->s_writers_key[i]))
 			goto fail;
 	}
-	init_waitqueue_head(&s->s_writers.wait_unfrozen);
 	s->s_bdi = &noop_backing_dev_info;
 	s->s_flags = flags;
 	if (s->s_user_ns != &init_user_ns)
@@ -1706,7 +1705,6 @@ int freeze_super(struct super_block *sb)
 	if (ret) {
 		sb->s_writers.frozen = SB_UNFROZEN;
 		sb_freeze_unlock(sb, SB_FREEZE_PAGEFAULT);
-		wake_up(&sb->s_writers.wait_unfrozen);
 		deactivate_locked_super(sb);
 		return ret;
 	}
@@ -1722,7 +1720,6 @@ int freeze_super(struct super_block *sb)
 				"VFS:Filesystem freeze failed\n");
 			sb->s_writers.frozen = SB_UNFROZEN;
 			sb_freeze_unlock(sb, SB_FREEZE_FS);
-			wake_up(&sb->s_writers.wait_unfrozen);
 			deactivate_locked_super(sb);
 			return ret;
 		}
@@ -1768,7 +1765,6 @@ static int thaw_super_locked(struct super_block *sb)
 	sb->s_writers.frozen = SB_UNFROZEN;
 	sb_freeze_unlock(sb, SB_FREEZE_FS);
 out:
-	wake_up(&sb->s_writers.wait_unfrozen);
 	deactivate_locked_super(sb);
 	return 0;
 }
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 21a981680856..3b65a6194485 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1146,7 +1146,6 @@ enum {
 
 struct sb_writers {
 	int				frozen;		/* Is sb frozen? */
-	wait_queue_head_t		wait_unfrozen;	/* wait for thaw */
 	struct percpu_rw_semaphore	rw_sem[SB_FREEZE_LEVELS];
 };
 
-- 
2.35.3

Re: [PATCH] fs: Drop wait_unfrozen wait queue

[Christian Brauner]

On Thu, May 25, 2023 at 04:17:10PM +0200, Jan Kara wrote:
> wait_unfrozen waitqueue is used only in quota code to wait for
> filesystem to become unfrozen. In that place we can just use
> sb_start_write() - sb_end_write() pair to achieve the same. So just
> remove the waitqueue.
> 
> Signed-off-by: Jan Kara <jack@suse.cz>
> ---

Removing code. I'm all here for it...
Reviewed-by: Christian Brauner <brauner@kernel.org>

>  fs/quota/quota.c   | 5 +++--
>  fs/super.c         | 4 ----
>  include/linux/fs.h | 1 -
>  3 files changed, 3 insertions(+), 7 deletions(-)
> 
> Guys, I can merge this cleanup through my tree since I don't expect any
> conflicts and the generic part is pure removal of unused code.

There'll likely be another set of fixes I'll take next week but I
honestly don't care. But seems that this isn't really urgent so why not
just wait for the merge window?

Re: [PATCH] fs: Drop wait_unfrozen wait queue

[Jan Kara]

On Thu 25-05-23 20:16:04, Christian Brauner wrote:
> On Thu, May 25, 2023 at 04:17:10PM +0200, Jan Kara wrote:
> > wait_unfrozen waitqueue is used only in quota code to wait for
> > filesystem to become unfrozen. In that place we can just use
> > sb_start_write() - sb_end_write() pair to achieve the same. So just
> > remove the waitqueue.
> > 
> > Signed-off-by: Jan Kara <jack@suse.cz>
> > ---
> 
> Removing code. I'm all here for it...
> Reviewed-by: Christian Brauner <brauner@kernel.org>
> 
> >  fs/quota/quota.c   | 5 +++--
> >  fs/super.c         | 4 ----
> >  include/linux/fs.h | 1 -
> >  3 files changed, 3 insertions(+), 7 deletions(-)
> > 
> > Guys, I can merge this cleanup through my tree since I don't expect any
> > conflicts and the generic part is pure removal of unused code.
> 
> There'll likely be another set of fixes I'll take next week but I
> honestly don't care. But seems that this isn't really urgent so why not
> just wait for the merge window?

Sure, I'll queue the patch for the next merge window. Thanks for review!

								Honza

-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR