md: limit mdstat resync progress to max_sectors

There is a small window near the end of md_do_sync where mddev->curr_resync
can be equal to MaxSector.

If status_resync is called during this window, the resulting /proc/mdstat
output contains a HUGE number of = signs due to the very large curr_resync:

Personalities : [raid1]
md123 : active raid1 sdd3[2] sdb3[0]
  204736 blocks super 1.0 [2/1] [U_]
  [=====================================================================
   ... (82 MB more) ...
   ================>]  recovery =429496729.3% (9223372036854775807/204736)
   finish=0.2min speed=12796K/sec
  bitmap: 0/1 pages [0KB], 65536KB chunk

Modify status_resync to ensure the resync variable doesn't exceed
the array's max_sectors.

Signed-off-by: Nate Dailey <nate.dailey@stratus.com>
Acked-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 41c050b59ec4..4e4dee0ec2de 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -7605,7 +7605,9 @@ static int status_resync(struct seq_file *seq, struct mddev *mddev)
                 if (test_bit(MD_RECOVERY_DONE, &mddev->recovery))
                         /* Still cleaning up */
                         resync = max_sectors;
-        } else
+        } else if (resync > max_sectors)
+                resync = max_sectors;
+        else
                 resync -= atomic_read(&mddev->recovery_active);
 
         if (resync == 0) {