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[v2,3/9] ext4: tell DAX the size of allocation holes

Message ID 20160823220419.11717-4-ross.zwisler@linux.intel.com
State Superseded, archived
Headers show

Commit Message

Ross Zwisler Aug. 23, 2016, 10:04 p.m. UTC 
When DAX calls _ext4_get_block() and the file offset points to a hole we
currently don't set bh->b_size.  When we re-enable PMD faults DAX will
need bh->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.

_ext4_get_block() has the hole size information from ext4_map_blocks(), so
populate bh->b_size.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/inode.c | 3 +++
 1 file changed, 3 insertions(+)
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Patch

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 0900cb4..9075fac 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -759,6 +759,9 @@  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;
 }