Re: [PATCH v2] xfs: don't eat an EIO/ENOSPC writeback error when scrubbing data fork

[Dave Chinner <david@fromorbit.com>]

On Mon, Jun 22, 2020 at 08:50:10PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> The data fork scrubber calls filemap_write_and_wait to flush dirty pages
> and delalloc reservations out to disk prior to checking the data fork's
> extent mappings.  Unfortunately, this means that scrub can consume the
> EIO/ENOSPC errors that would otherwise have stayed around in the address
> space until (we hope) the writer application calls fsync to persist data
> and collect errors.  The end result is that programs that wrote to a
> file might never see the error code and proceed as if nothing were
> wrong.
> 
> xfs_scrub is not in a position to notify file writers about the
> writeback failure, and it's only here to check metadata, not file
> contents.  Therefore, if writeback fails, we should stuff the error code
> back into the address space so that an fsync by the writer application
> can pick that up.
> 
> Fixes: 99d9d8d05da2 ("xfs: scrub inode block mappings")
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
> v2: explain why it's ok to keep going even if writeback fails

Looks good.

Reviewed-by: Dave Chinner <dchinner@redhat.com>
-- 
Dave Chinner
david@fromorbit.com