[PATCH 3.10 154/319] ext4: allow DAX writeback for hole punch

[Willy Tarreau]

From: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>

commit cca32b7eeb4ea24fa6596650e06279ad9130af98 upstream.

Currently when doing a DAX hole punch with ext4 we fail to do a writeback.
This is because the logic around filemap_write_and_wait_range() in
ext4_punch_hole() only looks for dirty page cache pages in the radix tree,
not for dirty DAX exceptional entries.

Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Willy Tarreau <w@xxxxxx>
---
 fs/ext4/inode.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index a187055..31179ba 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3610,7 +3610,7 @@ int ext4_can_truncate(struct inode *inode)
 }
 
 /*
- * ext4_punch_hole: punches a hole in a file by releaseing the blocks
+ * ext4_punch_hole: punches a hole in a file by releasing the blocks
  * associated with the given offset and length
  *
  * @inode:  File inode
@@ -3646,7 +3646,7 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
 	 * Write out all dirty pages to avoid race conditions
 	 * Then release them.
 	 */
-	if (mapping->nrpages && mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
+	if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
 		ret = filemap_write_and_wait_range(mapping, offset,
 						   offset + length - 1);
 		if (ret)
-- 
2.8.0.rc2.1.gbe9624a