linux-ext4 - Re: [PATCH v7 21/22] xfs: minimal conversion to errseq

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Message-ID: <20170626152241.GC4733@birch.djwong.org>
Date:   Mon, 26 Jun 2017 08:22:41 -0700
From:   "Darrick J. Wong" <darrick.wong@...cle.com>
To:     Jeff Layton <jlayton@...hat.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Al Viro <viro@...IV.linux.org.uk>, Jan Kara <jack@...e.cz>,
        tytso@....edu, axboe@...nel.dk, mawilcox@...rosoft.com,
        ross.zwisler@...ux.intel.com, corbet@....net,
        Chris Mason <clm@...com>, Josef Bacik <jbacik@...com>,
        David Sterba <dsterba@...e.com>,
        Carlos Maiolino <cmaiolino@...hat.com>,
        Eryu Guan <eguan@...hat.com>,
        David Howells <dhowells@...hat.com>,
        Christoph Hellwig <hch@...radead.org>,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        linux-ext4@...r.kernel.org, linux-xfs@...r.kernel.org,
        linux-btrfs@...r.kernel.org, linux-block@...r.kernel.org
Subject: Re: [PATCH v7 21/22] xfs: minimal conversion to errseq_t writeback
 error reporting

On Fri, Jun 16, 2017 at 03:34:26PM -0400, Jeff Layton wrote:
> Just check and advance the data errseq_t in struct file before
> before returning from fsync on normal files. Internal filemap_*
> callers are left as-is.
> 
> Signed-off-by: Jeff Layton <jlayton@...hat.com>
> ---
>  fs/xfs/xfs_file.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 5fb5a0958a14..bc3b1575e8db 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -134,7 +134,7 @@ xfs_file_fsync(
>  	struct inode		*inode = file->f_mapping->host;
>  	struct xfs_inode	*ip = XFS_I(inode);
>  	struct xfs_mount	*mp = ip->i_mount;
> -	int			error = 0;
> +	int			error = 0, err2;
>  	int			log_flushed = 0;
>  	xfs_lsn_t		lsn = 0;
>  
> @@ -142,10 +142,12 @@ xfs_file_fsync(
>  
>  	error = filemap_write_and_wait_range(inode->i_mapping, start, end);
>  	if (error)
> -		return error;
> +		goto out;
>  
> -	if (XFS_FORCED_SHUTDOWN(mp))
> -		return -EIO;
> +	if (XFS_FORCED_SHUTDOWN(mp)) {
> +		error = -EIO;
> +		goto out;
> +	}
>  
>  	xfs_iflags_clear(ip, XFS_ITRUNCATED);
>  
> @@ -197,6 +199,11 @@ xfs_file_fsync(
>  	    mp->m_logdev_targp == mp->m_ddev_targp)
>  		xfs_blkdev_issue_flush(mp->m_ddev_targp);
>  
> +out:
> +	err2 = filemap_report_wb_err(file);

Could we have a comment here to remind anyone reading the code a year
from now that filemap_report_wb_err has side effects?  Pre-coffee me was
wondering why we'd bother calling filemap_report_wb_err in the
XFS_FORCED_SHUTDOWN case, then remembered that it touches data
structures.

The first sentence of the commit message (really, the word 'advance')
added as a comment was adequate to remind me of the side effects.

Once that's added,
Reviewed-by: Darrick J. Wong <darrick.wong@...cle.com>

--D

> +	if (!error)
> +		error = err2;
> +
>  	return error;
>  }
>  
> -- 
> 2.13.0
> 
> --
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