[PATCH] md: fix resync speed calculation for restarted resyncs

We introduced 'io_sectors' recently so we could count the sectors that causes
io during resync separate from sectors which didn't cause IO - there can be a
difference if a bitmap is being used to accelerate resync.

However when a speed is reported, we find the number of sectors processed
recently by subtracting an oldish io_sectors count from a current
'curr_resync' count.  This is wrong because curr_resync counts all sectors,
not just io sectors.

So, add a field to mddev to store the curren io_sectors separately from
curr_resync, and use that in the calculations.

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 6 insertions, 4 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index fb50e5642c63..4bd3ccf363bd 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -2719,7 +2719,7 @@ static ssize_t
 sync_speed_show(mddev_t *mddev, char *page)
 {
         unsigned long resync, dt, db;
-        resync = (mddev->curr_resync - atomic_read(&mddev->recovery_active));
+        resync = (mddev->curr_mark_cnt - atomic_read(&mddev->recovery_active));
         dt = ((jiffies - mddev->resync_mark) / HZ);
         if (!dt) dt++;
         db = resync - (mddev->resync_mark_cnt);
@@ -4687,12 +4687,13 @@ static void status_resync(struct seq_file *seq, mddev_t * mddev)
          */
         dt = ((jiffies - mddev->resync_mark) / HZ);
         if (!dt) dt++;
-        db = resync - (mddev->resync_mark_cnt/2);
-        rt = (dt * ((unsigned long)(max_blocks-resync) / (db/100+1)))/100;
+        db = (mddev->curr_mark_cnt - atomic_read(&mddev->recovery_active))
+                - mddev->resync_mark_cnt;
+        rt = (dt * ((unsigned long)(max_blocks-resync) / (db/2/100+1)))/100;
 
         seq_printf(seq, " finish=%lu.%lumin", rt / 60, (rt % 60)/6);
 
-        seq_printf(seq, " speed=%ldK/sec", db/dt);
+        seq_printf(seq, " speed=%ldK/sec", db/2/dt);
 }
 
 static void *md_seq_start(struct seq_file *seq, loff_t *pos)
@@ -5203,6 +5204,7 @@ void md_do_sync(mddev_t *mddev)
 
                 j += sectors;
                 if (j>1) mddev->curr_resync = j;
+                mddev->curr_mark_cnt = io_sectors;
                 if (last_check == 0)
                         /* this is the earliers that rebuilt will be
                          * visible in /proc/mdstat