Re: [PATCH 4.19 070/243] xfs: extent shifting doesnt fully invalidate page cache

[Nobuhiro Iwamatsu]

On Wed, Dec 11, 2019 at 04:03:52PM +0100, Greg Kroah-Hartman wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
> 
> [ Upstream commit 7f9f71be84bcab368e58020a42f6d0dd97adf0ce ]
> 
> The extent shifting code uses a flush and invalidate mechainsm prior
> to shifting extents around. This is similar to what
> xfs_free_file_space() does, but it doesn't take into account things
> like page cache vs block size differences, and it will fail if there
> is a page that it currently busy.
> 
> xfs_flush_unmap_range() handles all of these cases, so just convert
> xfs_prepare_shift() to us that mechanism rather than having it's own
> special sauce.
> 
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>


This commit also required following commit:

commit 1749d1ea89bdf3181328b7d846e609d5a0e53e50
Author: Brian Foster <bfoster@xxxxxxxxxx>
Date:   Fri Apr 26 07:30:24 2019 -0700

    xfs: add missing error check in xfs_prepare_shift()

    xfs_prepare_shift() fails to check the error return from
    xfs_flush_unmap_range(). If the latter fails, that could lead to an
    insert/collapse range operation over a delalloc range, which is not
    supported.

    Add an error check and return appropriately. This is reproduced
    rarely by generic/475.

    Fixes: 7f9f71be84bc ("xfs: extent shifting doesn't fully invalidate page cache")
    Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
    Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
    Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
    Reviewed-by: Allison Collins <allison.henderson@xxxxxxxxxx>
    Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx>

Best regards,
  Nobuhirio