ext4: tell DAX the size of allocation holes

When DAX calls _ext4_get_block() and the file offset points to a hole we
currently don't set bh->b_size.  This is current worked around via
buffer_size_valid() in fs/dax.c.

_ext4_get_block() has the hole size information from ext4_map_blocks(), so
populate bh->b_size so we can remove buffer_size_valid() in a later patch.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 9c064727ed62978e95f27f2fe73c5e946ce672b0..3d58b2b477e8edee3bff7f5b3be26017e95c4aa2 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -767,6 +767,9 @@ static int _ext4_get_block(struct inode *inode, sector_t iblock,
                ext4_update_bh_state(bh, map.m_flags);
                bh->b_size = inode->i_sb->s_blocksize * map.m_len;
                ret = 0;
+       } else if (ret == 0) {
+               /* hole case, need to fill in bh->b_size */
+               bh->b_size = inode->i_sb->s_blocksize * map.m_len;
        }
        return ret;
 }