ext4: allow DAX writeback for hole punch

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@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 9189b0a7b2112f33da51c49824f4b5f84143f015..c71d2941a45be1f1d2eeaed661a7f34af0293866 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3645,7 +3645,7 @@ int ext4_update_disksize_before_punch(struct inode *inode, loff_t offset,
 }
 
 /*
- * 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
@@ -3674,7 +3674,7 @@ int ext4_punch_hole(struct inode *inode, 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)