nilfs2: insert checkpoint number in segment summary header
This adds a field to record the latest checkpoint number in the
nilfs_segment_summary structure. This will help to recover the latest
checkpoint number from logs on disk. This field is intended for
crucial cases in which super blocks have lost pointer to the latest
log.
Even though this will change the disk format, both backward and
forward compatibility is preserved by a size field prepared in the
segment summary header.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
diff --git a/include/linux/nilfs2_fs.h b/include/linux/nilfs2_fs.h
index f960e1d..6505c00 100644
--- a/include/linux/nilfs2_fs.h
+++ b/include/linux/nilfs2_fs.h
@@ -377,6 +377,7 @@
* @ss_nfinfo: number of finfo structures
* @ss_sumbytes: total size of segment summary in bytes
* @ss_pad: padding
+ * @ss_cno: checkpoint number
*/
struct nilfs_segment_summary {
__le32 ss_datasum;
@@ -391,6 +392,7 @@
__le32 ss_nfinfo;
__le32 ss_sumbytes;
__le32 ss_pad;
+ __le64 ss_cno;
/* array of finfo structures */
};