DM RAID: Set recovery flags on resume

Properly initialize MD recovery flags when resuming device-mapper devices.

When a device-mapper device is suspended, all I/O must stop.  This is done by
calling 'md_stop_writes' and 'mddev_suspend'.  These calls in-turn manipulate
the recovery flags - including setting 'MD_RECOVERY_FROZEN'.  The DM device
may have been suspended while recovery was not yet complete, so the process
needs to pick-up where it left off.  Since 'mddev_resume' does not unset
'MD_RECOVERY_FROZEN' and set 'MD_RECOVERY_NEEDED', we must do it ourselves.
'MD_RECOVERY_NEEDED' can safely be set in 'mddev_resume', but 'MD_RECOVERY_FROZEN'
must be set outside of 'mddev_resume' due to how MD handles RAID reshaping.
(e.g.  It is possible for a user to delay reshaping a RAID5->RAID6 by purposefully
setting 'MD_RECOVERY_FROZEN'.  Clearing it in 'mddev_resume' would override the
desired behavior.)

Because 'mddev_resume' already unconditionally calls 'md_wakeup_thread(mddev->thread)'
there is no need to make this call from 'raid_resume' since it calls 'mddev_resume'.

Also clean up where  level_store calls mddev_resume() - it current
duplicates some of the funcitons of that call. - NB

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>

2 files changed, 4 insertions, 5 deletions

diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 73a068da10d..ea2d90c78f7 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -1252,9 +1252,9 @@ static void raid_resume(struct dm_target *ti)
         if (!rs->bitmap_loaded) {
                 bitmap_load(&rs->md);
                 rs->bitmap_loaded = 1;
-        } else
-                md_wakeup_thread(rs->md.thread);
+        }
 
+        clear_bit(MD_RECOVERY_FROZEN, &rs->md.recovery);
         mddev_resume(&rs->md);
 }
 
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 86adf4ac46c..4c9836885d3 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -402,6 +402,7 @@ void mddev_resume(struct mddev *mddev)
         wake_up(&mddev->sb_wait);
         mddev->pers->quiesce(mddev, 0);
 
+        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
         md_wakeup_thread(mddev->thread);
         md_wakeup_thread(mddev->sync_thread); /* possibly kick off a reshape */
 }
@@ -3673,10 +3674,8 @@ level_store(struct mddev *mddev, const char *buf, size_t len)
                 del_timer_sync(&mddev->safemode_timer);
         }
         pers->run(mddev);
-        mddev_resume(mddev);
         set_bit(MD_CHANGE_DEVS, &mddev->flags);
-        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
-        md_wakeup_thread(mddev->thread);
+        mddev_resume(mddev);
         sysfs_notify(&mddev->kobj, NULL, "level");
         md_new_event(mddev);
         return rv;