[PATCH 3/6] xfs: don't zero partial page cache pages during O_DIRECT writes

[Dave Chinner <david@xxxxxxxxxxxxx>]

From: Dave Chinner <dchinner@xxxxxxxxxx>

Similar to direct IO reads, direct IO writes are using
truncate_pagecache_range to invalidate the page cache. This is
incorrect due to the sub-block zeroing in the page cache that
truncate_pagecache_range() triggers.

This patch fixes things by using invalidate_inode_pages2_range
instead.  It preserves the page cache invalidation, but won't zero
any pages.

cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
---
 fs/xfs/xfs_file.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 827cfb2..19917fa 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -644,7 +644,15 @@ xfs_file_dio_aio_write(
                                                    pos, -1);
                if (ret)
                        goto out;
-               truncate_pagecache_range(VFS_I(ip), pos, -1);
+               /*
+                * Invalidate whole pages. This can return an error if
+                * we fail to invalidate a page, but this should never
+                * happen on XFS. Warn if it does fail.
+                */
+               ret = invalidate_inode_pages2_range(VFS_I(ip)->i_mapping,
+                                               pos >> PAGE_CACHE_SHIFT, -1);
+               WARN_ON_ONCE(ret);
+               ret = 0;
        }
 
        /*
-- 
2.0.0