Make sure all changes to md/degraded are notified.

When a device fails, when a spare is activated, when
an array is reshaped, or when an array is started,
the extent to which the array is degraded can change.

Signed-off-by: Neil Brown <neilb@suse.de>

2 files changed, 12 insertions, 1 deletions

diff --git a/Documentation/md.txt b/Documentation/md.txt
index c05bfb55659e..eb6e69e3732e 100644
--- a/Documentation/md.txt
+++ b/Documentation/md.txt
@@ -392,6 +392,13 @@ also have
       achieved. In that case, the transition to "recover" isn't
       notified, but the transition away is.
 
+   degraded
+      This contains a count of the number of devices by which the
+      arrays is degraded.  So an optimal array with show '0'.  A
+      single failed/missing drive will show '1', etc.
+      This file responds to select/poll, any increase or decrease
+      in the count of missing devices will trigger an event.
+
    mismatch_count
       When performing 'check' and 'repair', and possibly when
       performing 'resync', md will count the number of errors that are
diff --git a/drivers/md/md.c b/drivers/md/md.c
index c26dcad8a3ac..60d4cad88c20 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -2969,6 +2969,7 @@ action_store(mddev_t *mddev, const char *page, size_t len)
                 err = mddev->pers->start_reshape(mddev);
                 if (err)
                         return err;
+                sysfs_notify(&mddev->kobj, NULL, "degraded");
         } else {
                 if (cmd_match(page, "check"))
                         set_bit(MD_RECOVERY_CHECK, &mddev->recovery);
@@ -3686,6 +3687,7 @@ static int do_md_run(mddev_t * mddev)
         md_new_event(mddev);
         sysfs_notify(&mddev->kobj, NULL, "array_state");
         sysfs_notify(&mddev->kobj, NULL, "sync_action");
+        sysfs_notify(&mddev->kobj, NULL, "degraded");
         kobject_uevent(&mddev->gendisk->dev.kobj, KOBJ_CHANGE);
         return 0;
 }
@@ -6049,7 +6051,9 @@ void md_check_recovery(mddev_t *mddev)
                         if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
                                 /* success...*/
                                 /* activate any spares */
-                                mddev->pers->spare_active(mddev);
+                                if (mddev->pers->spare_active(mddev))
+                                        sysfs_notify(&mddev->kobj, NULL,
+                                                     "degraded");
                         }
                         md_update_sb(mddev, 1);