[PATCH v2 2/9] ext2: tell DAX the size of allocation holes

[Ross Zwisler]

When DAX calls ext2_get_block() and the file offset points to a hole we
currently don't set bh_result->b_size.  When we re-enable PMD faults DAX
will need bh_result->b_size to tell it the size of the hole so it can
decide whether to fault in a 4 KiB zero page or a 2 MiB zero page.

Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
---
 fs/ext2/inode.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index d5c7d09..dd55d74 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -773,6 +773,9 @@ int ext2_get_block(struct inode *inode, sector_t iblock, struct buffer_head *bh_
 	if (ret > 0) {
 		bh_result->b_size = (ret << inode->i_blkbits);
 		ret = 0;
+	} else if (ret == 0) {
+		/* hole case, need to fill in bh_result->b_size */
+		bh_result->b_size = 1 << inode->i_blkbits;
 	}
 	return ret;
 
-- 
2.9.0