[PATCH] md: replace magic numbers in sb_dirty with well defined bit flags

Instead of magic numbers (0,1,2,3) in sb_dirty, we have
some flags instead:
MD_CHANGE_DEVS
   Some device state has changed requiring superblock update
   on all devices.
MD_CHANGE_CLEAN
   The array has transitions from 'clean' to 'dirty' or back,
   requiring a superblock update on active devices, but possibly
   not on spares
MD_CHANGE_PENDING
   A superblock update is underway.

We wait for an update to complete by waiting for all flags to be clear.  A
flag can be set at any time, even during an update, without risk that the
change will be lost.

Stop exporting md_update_sb - isn't needed.

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, 4 insertions, 4 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 450066007160..d5a06b258427 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -696,7 +696,7 @@ static void error(mddev_t *mddev, mdk_rdev_t *rdev)
         PRINTK("raid5: error called\n");
 
         if (!test_bit(Faulty, &rdev->flags)) {
-                mddev->sb_dirty = 1;
+                set_bit(MD_CHANGE_DEVS, &mddev->flags);
                 if (test_bit(In_sync, &rdev->flags)) {
                         conf->working_disks--;
                         mddev->degraded++;
@@ -2781,9 +2781,9 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped
                 wait_event(conf->wait_for_overlap,
                            atomic_read(&conf->reshape_stripes)==0);
                 mddev->reshape_position = conf->expand_progress;
-                mddev->sb_dirty = 1;
+                set_bit(MD_CHANGE_DEVS, &mddev->flags);
                 md_wakeup_thread(mddev->thread);
-                wait_event(mddev->sb_wait, mddev->sb_dirty == 0 ||
+                wait_event(mddev->sb_wait, mddev->flags == 0 ||
                            kthread_should_stop());
                 spin_lock_irq(&conf->device_lock);
                 conf->expand_lo = mddev->reshape_position;
@@ -3605,7 +3605,7 @@ static int raid5_start_reshape(mddev_t *mddev)
         mddev->degraded = (conf->raid_disks - conf->previous_raid_disks) - added_devices;
         mddev->raid_disks = conf->raid_disks;
         mddev->reshape_position = 0;
-        mddev->sb_dirty = 1;
+        set_bit(MD_CHANGE_DEVS, &mddev->flags);
 
         clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
         clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);