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>

1 files changed, 3 insertions, 1 deletions

diff --git a/fs/nilfs2/segbuf.c b/fs/nilfs2/segbuf.c
index 9f83bc02593c..2e6a2723b8fa 100644
--- a/fs/nilfs2/segbuf.c
+++ b/fs/nilfs2/segbuf.c
@@ -134,7 +134,7 @@ int nilfs_segbuf_extend_payload(struct nilfs_segment_buffer *segbuf,
 }
 
 int nilfs_segbuf_reset(struct nilfs_segment_buffer *segbuf, unsigned flags,
-                       time_t ctime)
+                       time_t ctime, __u64 cno)
 {
         int err;
 
@@ -147,6 +147,7 @@ int nilfs_segbuf_reset(struct nilfs_segment_buffer *segbuf, unsigned flags,
         segbuf->sb_sum.sumbytes = sizeof(struct nilfs_segment_summary);
         segbuf->sb_sum.nfinfo = segbuf->sb_sum.nfileblk = 0;
         segbuf->sb_sum.ctime = ctime;
+        segbuf->sb_sum.cno = cno;
         return 0;
 }
 
@@ -172,6 +173,7 @@ void nilfs_segbuf_fill_in_segsum(struct nilfs_segment_buffer *segbuf)
         raw_sum->ss_nfinfo   = cpu_to_le32(segbuf->sb_sum.nfinfo);
         raw_sum->ss_sumbytes = cpu_to_le32(segbuf->sb_sum.sumbytes);
         raw_sum->ss_pad      = 0;
+        raw_sum->ss_cno      = cpu_to_le64(segbuf->sb_sum.cno);
 }
 
 /*