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authorNeilBrown <neilb@suse.de>2006-08-27 01:23:49 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-08-27 11:01:31 -0700
commit84692195969b83f0ba57dc33ecf73e6c124dd186 (patch)
tree6ef3e71914c83cf66330f5c0cf6cf2edebb0404a
parent45f17e0c2ae05c133a348452690de0e5fa863293 (diff)
downloadlinux-stericsson-84692195969b83f0ba57dc33ecf73e6c124dd186.tar.gz
[PATCH] md: avoid backward event updates in md superblock when degraded.
If we - shut down a clean array, - restart with one (or more) drive(s) missing - make some changes - pause, so that they array gets marked 'clean', the event count on the superblock of included drives will be the same as that of the removed drives. So adding the removed drive back in will cause it to be included with no resync. To avoid this, we only update the eventcount backwards when the array is not degraded. In this case there can (should) be no non-connected drives that we can get confused with, and this is the particular case where updating-backwards is valuable. Signed-off-by: Neil Brown <neilb@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--drivers/md/md.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c
index b6d16022a53e..8dbab2ef3885 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1597,6 +1597,19 @@ void md_update_sb(mddev_t * mddev)
repeat:
spin_lock_irq(&mddev->write_lock);
+
+ if (mddev->degraded && mddev->sb_dirty == 3)
+ /* If the array is degraded, then skipping spares is both
+ * dangerous and fairly pointless.
+ * Dangerous because a device that was removed from the array
+ * might have a event_count that still looks up-to-date,
+ * so it can be re-added without a resync.
+ * Pointless because if there are any spares to skip,
+ * then a recovery will happen and soon that array won't
+ * be degraded any more and the spare can go back to sleep then.
+ */
+ mddev->sb_dirty = 1;
+
sync_req = mddev->in_sync;
mddev->utime = get_seconds();
if (mddev->sb_dirty == 3)