Make sure all changes to md/array_state are notified.

Changes in md/array_state could be of interest to a monitoring
program.  So make sure all changes trigger a notification.

Exceptions:
   changing active_idle to active is not reported because it
      is frequent and not interesting.
   changing active to active_idle is only reported on arrays
      with externally managed metadata, as it is not interesting
      otherwise.

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

2 files changed, 29 insertions, 5 deletions

diff --git a/Documentation/md.txt b/Documentation/md.txt
index a8b430627473..dca97ba4944a 100644
--- a/Documentation/md.txt
+++ b/Documentation/md.txt
@@ -236,6 +236,11 @@ All md devices contain:
      writing the word for the desired state, however some states
      cannot be explicitly set, and some transitions are not allowed.
 
+     Select/poll works on this file.  All changes except between
+        active_idle and active (which can be frequent and are not
+        very interesting) are notified.  active->active_idle is
+        reported if the metadata is externally managed.
+
      clear
          No devices, no size, no level
          Writing is equivalent to STOP_ARRAY ioctl
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 1442761ac98e..5b9d4fe4e6e4 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -2716,8 +2716,10 @@ array_state_store(mddev_t *mddev, const char *buf, size_t len)
         }
         if (err)
                 return err;
-        else
+        else {
+                sysfs_notify(&mddev->kobj, NULL, "array_state");
                 return len;
+        }
 }
 static struct md_sysfs_entry md_array_state =
 __ATTR(array_state, S_IRUGO|S_IWUSR, array_state_show, array_state_store);
@@ -3408,7 +3410,11 @@ static void md_safemode_timeout(unsigned long data)
 {
         mddev_t *mddev = (mddev_t *) data;
 
-        mddev->safemode = 1;
+        if (!atomic_read(&mddev->writes_pending)) {
+                mddev->safemode = 1;
+                if (mddev->external)
+                        sysfs_notify(&mddev->kobj, NULL, "array_state");
+        }
         md_wakeup_thread(mddev->thread);
 }
 
@@ -3675,6 +3681,7 @@ static int do_md_run(mddev_t * mddev)
 
         mddev->changed = 1;
         md_new_event(mddev);
+        sysfs_notify(&mddev->kobj, NULL, "array_state");
         kobject_uevent(&mddev->gendisk->dev.kobj, KOBJ_CHANGE);
         return 0;
 }
@@ -3709,6 +3716,8 @@ static int restart_array(mddev_t *mddev)
                 md_wakeup_thread(mddev->thread);
                 md_wakeup_thread(mddev->sync_thread);
                 err = 0;
+                sysfs_notify(&mddev->kobj, NULL, "array_state");
+
         } else
                 err = -EINVAL;
 
@@ -3879,6 +3888,7 @@ static int do_md_stop(mddev_t * mddev, int mode)
                         mdname(mddev));
         err = 0;
         md_new_event(mddev);
+        sysfs_notify(&mddev->kobj, NULL, "array_state");
 out:
         return err;
 }
@@ -4876,8 +4886,9 @@ static int md_ioctl(struct inode *inode, struct file *file,
             mddev->ro && mddev->pers) {
                 if (mddev->ro == 2) {
                         mddev->ro = 0;
-                set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
-                md_wakeup_thread(mddev->thread);
+                        sysfs_notify(&mddev->kobj, NULL, "array_state");
+                        set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+                        md_wakeup_thread(mddev->thread);
 
                 } else {
                         err = -EROFS;
@@ -5516,6 +5527,7 @@ void md_done_sync(mddev_t *mddev, int blocks, int ok)
  */
 void md_write_start(mddev_t *mddev, struct bio *bi)
 {
+        int did_change = 0;
         if (bio_data_dir(bi) != WRITE)
                 return;
 
@@ -5526,6 +5538,7 @@ void md_write_start(mddev_t *mddev, struct bio *bi)
                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
                 md_wakeup_thread(mddev->thread);
                 md_wakeup_thread(mddev->sync_thread);
+                did_change = 1;
         }
         atomic_inc(&mddev->writes_pending);
         if (mddev->safemode == 1)
@@ -5536,10 +5549,12 @@ void md_write_start(mddev_t *mddev, struct bio *bi)
                         mddev->in_sync = 0;
                         set_bit(MD_CHANGE_CLEAN, &mddev->flags);
                         md_wakeup_thread(mddev->thread);
+                        did_change = 1;
                 }
                 spin_unlock_irq(&mddev->write_lock);
-                sysfs_notify(&mddev->kobj, NULL, "array_state");
         }
+        if (did_change)
+                sysfs_notify(&mddev->kobj, NULL, "array_state");
         wait_event(mddev->sb_wait,
                    !test_bit(MD_CHANGE_CLEAN, &mddev->flags) &&
                    !test_bit(MD_CHANGE_PENDING, &mddev->flags));
@@ -5991,18 +6006,22 @@ void md_check_recovery(mddev_t *mddev)
                 int spares = 0;
 
                 if (!mddev->external) {
+                        int did_change = 0;
                         spin_lock_irq(&mddev->write_lock);
                         if (mddev->safemode &&
                             !atomic_read(&mddev->writes_pending) &&
                             !mddev->in_sync &&
                             mddev->recovery_cp == MaxSector) {
                                 mddev->in_sync = 1;
+                                did_change = 1;
                                 if (mddev->persistent)
                                         set_bit(MD_CHANGE_CLEAN, &mddev->flags);
                         }
                         if (mddev->safemode == 1)
                                 mddev->safemode = 0;
                         spin_unlock_irq(&mddev->write_lock);
+                        if (did_change)
+                                sysfs_notify(&mddev->kobj, NULL, "array_state");
                 }
 
                 if (mddev->flags)