releases/3.16.3/xfs-don-t-zero-partial-page-cache-pages-during-o_direct-writes.patch

   1 From 834ffca6f7e345a79f6f2e2d131b0dfba8a4b67a Mon Sep 17 00:00:00 2001
   2 From: Dave Chinner <dchinner@redhat.com>
   3 Date: Tue, 2 Sep 2014 12:12:52 +1000
   4 Subject: xfs: don't zero partial page cache pages during O_DIRECT writes
   5
   6 From: Dave Chinner <dchinner@redhat.com>
   7
   8 commit 834ffca6f7e345a79f6f2e2d131b0dfba8a4b67a upstream.
   9
  10 Similar to direct IO reads, direct IO writes are using
  11 truncate_pagecache_range to invalidate the page cache. This is
  12 incorrect due to the sub-block zeroing in the page cache that
  13 truncate_pagecache_range() triggers.
  14
  15 This patch fixes things by using invalidate_inode_pages2_range
  16 instead.  It preserves the page cache invalidation, but won't zero
  17 any pages.
  18
  19 Signed-off-by: Dave Chinner <dchinner@redhat.com>
  20 Reviewed-by: Brian Foster <bfoster@redhat.com>
  21 Reviewed-by: Christoph Hellwig <hch@lst.de>
  22 Signed-off-by: Dave Chinner <david@fromorbit.com>
  23 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  24
  25 ---
  26  fs/xfs/xfs_file.c |   10 +++++++++-
  27  1 file changed, 9 insertions(+), 1 deletion(-)
  28
  29 --- a/fs/xfs/xfs_file.c
  30 +++ b/fs/xfs/xfs_file.c
  31 @@ -634,7 +634,15 @@ xfs_file_dio_aio_write(
  32                                                     pos, -1);
  33                 if (ret)
  34                         goto out;
  35 -               truncate_pagecache_range(VFS_I(ip), pos, -1);
  36 +               /*
  37 +                * Invalidate whole pages. This can return an error if
  38 +                * we fail to invalidate a page, but this should never
  39 +                * happen on XFS. Warn if it does fail.
  40 +                */
  41 +               ret = invalidate_inode_pages2_range(VFS_I(ip)->i_mapping,
  42 +                                               pos >> PAGE_CACHE_SHIFT, -1);
  43 +               WARN_ON_ONCE(ret);
  44 +               ret = 0;
  45         }
  46
  47         /*