Re: [PATCH 1/4] vfs: make freeze_super abort when sync_filesystem returns error

From: Jan Kara <jack@suse.cz>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, jack@suse.com
Subject: Re: [PATCH 1/4] vfs: make freeze_super abort when sync_filesystem returns error
Date: Wed, 26 Jan 2022 11:43:50 +0100	[thread overview]
Message-ID: <20220126104350.tk3v4mez37qbr7yx@quack3.lan> (raw)
In-Reply-To: <164316349509.2600168.11461158492068710281.stgit@magnolia>

On Tue 25-01-22 18:18:15, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
> 
> If we fail to synchronize the filesystem while preparing to freeze the
> fs, abort the freeze.
> 
> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> ---
>  fs/super.c |   19 ++++++++++++-------
>  1 file changed, 12 insertions(+), 7 deletions(-)

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> 
> 
> diff --git a/fs/super.c b/fs/super.c
> index 7af820ba5ad5..f1d4a193602d 100644
> --- a/fs/super.c
> +++ b/fs/super.c
> @@ -1616,11 +1616,9 @@ static void lockdep_sb_freeze_acquire(struct super_block *sb)
>  		percpu_rwsem_acquire(sb->s_writers.rw_sem + level, 0, _THIS_IP_);
>  }
>  
> -static void sb_freeze_unlock(struct super_block *sb)
> +static void sb_freeze_unlock(struct super_block *sb, int level)
>  {
> -	int level;
> -
> -	for (level = SB_FREEZE_LEVELS - 1; level >= 0; level--)
> +	for (level--; level >= 0; level--)
>  		percpu_up_write(sb->s_writers.rw_sem + level);
>  }
>  
> @@ -1691,7 +1689,14 @@ int freeze_super(struct super_block *sb)
>  	sb_wait_write(sb, SB_FREEZE_PAGEFAULT);
>  
>  	/* All writers are done so after syncing there won't be dirty data */
> -	sync_filesystem(sb);
> +	ret = sync_filesystem(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;
> +	}
>  
>  	/* Now wait for internal filesystem counter */
>  	sb->s_writers.frozen = SB_FREEZE_FS;
> @@ -1703,7 +1708,7 @@ int freeze_super(struct super_block *sb)
>  			printk(KERN_ERR
>  				"VFS:Filesystem freeze failed\n");
>  			sb->s_writers.frozen = SB_UNFROZEN;
> -			sb_freeze_unlock(sb);
> +			sb_freeze_unlock(sb, SB_FREEZE_FS);
>  			wake_up(&sb->s_writers.wait_unfrozen);
>  			deactivate_locked_super(sb);
>  			return ret;
> @@ -1748,7 +1753,7 @@ static int thaw_super_locked(struct super_block *sb)
>  	}
>  
>  	sb->s_writers.frozen = SB_UNFROZEN;
> -	sb_freeze_unlock(sb);
> +	sb_freeze_unlock(sb, SB_FREEZE_FS);
>  out:
>  	wake_up(&sb->s_writers.wait_unfrozen);
>  	deactivate_locked_super(sb);
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR