Re: [PATCH] dax: set errors in mapping when writeback fails

[Ross Zwisler <ross.zwisler@linux.intel.com>]

On Thu, May 25, 2017 at 06:47:46AM -0400, Jeff Layton wrote:
> Jan's description for this patch is much better than mine, so I'm
> quoting it verbatim here:
> 
> DAX currently doesn't set errors in the mapping when cache flushing
> fails in dax_writeback_mapping_range(). Since this function can get
> called only from fsync(2) or sync(2), this is actually as good as it can
> currently get since we correctly propagate the error up from
> dax_writeback_mapping_range() to filemap_fdatawrite(). However in the
> future better writeback error handling will enable us to properly report
> these errors on fsync(2) even if there are multiple file descriptors
> open against the file or if sync(2) gets called before fsync(2). So
> convert DAX to using standard error reporting through the mapping.
> 
> Signed-off-by: Jeff Layton <jlayton@redhat.com>
> Reviewed-by: Jan Kara <jack@suse.cz>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Reviewed-and-Tested-by: Ross Zwisler <ross.zwisler@linux.intel.com>

Is this still part of a larger series, or are you trying to submit it on its
own?  On it's own this patch still suffers from the issue I reported here:

https://lkml.org/lkml/2017/3/6/976

> ---
>  fs/dax.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/dax.c b/fs/dax.c
> index c22eaf162f95..441280e15d5b 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -856,8 +856,10 @@ int dax_writeback_mapping_range(struct address_space *mapping,
>  
>  			ret = dax_writeback_one(bdev, dax_dev, mapping,
>  					indices[i], pvec.pages[i]);
> -			if (ret < 0)
> +			if (ret < 0) {
> +				mapping_set_error(mapping, ret);
>  				goto out;
> +			}
>  		}
>  	}
>  out:
> -- 
> 2.9.4
>