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

[Dave Chinner]

From: Dave Chinner <dchinner at redhat.com>

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 at vger.kernel.org
Signed-off-by: Dave Chinner <dchinner at redhat.com>
---
 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