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

Jan Kara
2023-06-12T11:35:19Z

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