Re: [PATCH 3/3] fs: Drop wait_unfrozen wait queue

[Jan Kara <jack@suse.cz>]

On Sun 11-06-23 20:15:34, Darrick J. Wong wrote:
> From: Jan Kara <jack@suse.cz>
> 
> 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>
> Reviewed-by: Darrick J. Wong <djwong@kernel.org>
> Signed-off-by: Darrick J. Wong <djwong@kernel.org>

I have this already queued in my tree for the merge window... :)

								Honza

> ---
>  fs/quota/quota.c   |    5 +++--
>  fs/super.c         |    4 ----
>  include/linux/fs.h |    1 -
>  3 files changed, 3 insertions(+), 7 deletions(-)
> 
> 
> 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 151e0eeff2c2..fd04dda6c5c0 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)
> @@ -1753,7 +1752,6 @@ int freeze_super(struct super_block *sb, enum freeze_holder who)
>  	if (ret) {
>  		sb->s_writers.frozen = SB_UNFROZEN;
>  		sb_freeze_unlock(sb, SB_FREEZE_PAGEFAULT);
> -		wake_up(&sb->s_writers.wait_unfrozen);
>  		wake_up_var(&sb->s_writers.frozen);
>  		deactivate_locked_super(sb);
>  		return ret;
> @@ -1770,7 +1768,6 @@ int freeze_super(struct super_block *sb, enum freeze_holder who)
>  				"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);
>  			wake_up_var(&sb->s_writers.frozen);
>  			deactivate_locked_super(sb);
>  			return ret;
> @@ -1853,7 +1850,6 @@ static int thaw_super_locked(struct super_block *sb, enum freeze_holder who)
>  	wake_up_var(&sb->s_writers.frozen);
>  	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 c58a560569b3..5870fbbecb81 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1147,7 +1147,6 @@ enum {
>  struct sb_writers {
>  	unsigned short			frozen;		/* Is sb frozen? */
>  	unsigned short			freeze_holders;	/* Who froze fs? */
> -	wait_queue_head_t		wait_unfrozen;	/* wait for thaw */
>  	struct percpu_rw_semaphore	rw_sem[SB_FREEZE_LEVELS];
>  };
>  
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR