linux-ext4 - Re: [PATCH v8 18/18] btrfs: minimal conversion to errseq

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Message-ID: <20170629141741.GC17251@infradead.org>
Date:   Thu, 29 Jun 2017 07:17:41 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     jlayton@...nel.org
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>,
        "Darrick J . Wong" <darrick.wong@...cle.com>,
        Carlos Maiolino <cmaiolino@...hat.com>,
        Eryu Guan <eguan@...hat.com>,
        David Howells <dhowells@...hat.com>,
        Christoph Hellwig <hch@...radead.org>,
        Liu Bo <bo.li.liu@...cle.com>, 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 v8 18/18] btrfs: minimal conversion to errseq_t writeback
 error reporting on fsync

On Thu, Jun 29, 2017 at 09:19:54AM -0400, jlayton@...nel.org wrote:
> From: Jeff Layton <jlayton@...hat.com>
> 
> Just check and advance the errseq_t in the file before returning.
> Internal callers of filemap_* functions are left as-is.
> 
> Signed-off-by: Jeff Layton <jlayton@...hat.com>
> ---
>  fs/btrfs/file.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
> index da1096eb1a40..1f57e1a523d9 100644
> --- a/fs/btrfs/file.c
> +++ b/fs/btrfs/file.c
> @@ -2011,7 +2011,7 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
>  	struct btrfs_root *root = BTRFS_I(inode)->root;
>  	struct btrfs_trans_handle *trans;
>  	struct btrfs_log_ctx ctx;
> -	int ret = 0;
> +	int ret = 0, err;
>  	bool full_sync = 0;
>  	u64 len;
>  
> @@ -2030,7 +2030,7 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
>  	 */
>  	ret = start_ordered_ops(inode, start, end);
>  	if (ret)
> -		return ret;
> +		goto out;
>  
>  	inode_lock(inode);
>  	atomic_inc(&root->log_batch);
> @@ -2227,6 +2227,9 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
>  		ret = btrfs_end_transaction(trans);
>  	}
>  out:
> +	err = file_check_and_advance_wb_err(file);
> +	if (!ret)
> +		ret = err;
>  	return ret > 0 ? -EIO : ret;

This means that we'll lose the exact error returned from
start_ordered_ops.  Beyond that I can't really provide good feedback
as the btrfs fsync code looks so much different from all the other
fs fsync code..