linux-kernel - Re: [PATCH v3 04/20] fs: check for writeback errors after syncing out buffers in generic_file

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Date:   Mon, 24 Apr 2017 17:46:13 +0200
From:   Jan Kara <jack@...e.cz>
To:     Jeff Layton <jlayton@...hat.com>
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-btrfs@...r.kernel.org, linux-ext4@...r.kernel.org,
        linux-cifs@...r.kernel.org, linux-mm@...ck.org,
        jfs-discussion@...ts.sourceforge.net, linux-xfs@...r.kernel.org,
        cluster-devel@...hat.com, linux-f2fs-devel@...ts.sourceforge.net,
        v9fs-developer@...ts.sourceforge.net, osd-dev@...n-osd.org,
        linux-nilfs@...r.kernel.org, linux-block@...r.kernel.org,
        dhowells@...hat.com, akpm@...ux-foundation.org, hch@...radead.org,
        ross.zwisler@...ux.intel.com, mawilcox@...rosoft.com,
        jack@...e.com, viro@...iv.linux.org.uk, corbet@....net,
        neilb@...e.de, clm@...com, tytso@....edu, axboe@...nel.dk
Subject: Re: [PATCH v3 04/20] fs: check for writeback errors after syncing
 out buffers in generic_file_fsync

On Mon 24-04-17 09:22:43, Jeff Layton wrote:
> ext2 currently does a test+clear of the AS_EIO flag, which is
> is problematic for some coming changes.
> 
> What we really need to do instead is call filemap_check_errors
> in __generic_file_fsync after syncing out the buffers. That
> will be sufficient for this case, and help other callers detect
> these errors properly as well.
> 
> With that, we don't need to twiddle it in ext2.
> 
> Suggested-by: Jan Kara <jack@...e.cz>
> Signed-off-by: Jeff Layton <jlayton@...hat.com>

Looks good to me. You can add:

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

								Honza
> ---
>  fs/ext2/file.c | 2 +-
>  fs/libfs.c     | 3 ++-
>  2 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ext2/file.c b/fs/ext2/file.c
> index b21891a6bfca..ed00e7ae0ef3 100644
> --- a/fs/ext2/file.c
> +++ b/fs/ext2/file.c
> @@ -177,7 +177,7 @@ int ext2_fsync(struct file *file, loff_t start, loff_t end, int datasync)
>  	struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
>  
>  	ret = generic_file_fsync(file, start, end, datasync);
> -	if (ret == -EIO || test_and_clear_bit(AS_EIO, &mapping->flags)) {
> +	if (ret == -EIO) {
>  		/* We don't really know where the IO error happened... */
>  		ext2_error(sb, __func__,
>  			   "detected IO error when writing metadata buffers");
> diff --git a/fs/libfs.c b/fs/libfs.c
> index a8b62e5d43a9..12a48ee442d3 100644
> --- a/fs/libfs.c
> +++ b/fs/libfs.c
> @@ -991,7 +991,8 @@ int __generic_file_fsync(struct file *file, loff_t start, loff_t end,
>  
>  out:
>  	inode_unlock(inode);
> -	return ret;
> +	err = filemap_check_errors(inode->i_mapping);
> +	return ret ? : err;
>  }
>  EXPORT_SYMBOL(__generic_file_fsync);
>  
> -- 
> 2.9.3
> 
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR