md: Don't test all of mddev->flags at once.

mddev->flags is mostly used to record if an update of the
metadata is needed.  Sometimes the whole field is tested
instead of just the important bits.  This makes it difficult
to introduce more state bits.

So replace all bare tests of mddev->flags with tests for the bits
that actually need testing.

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

drivers/md/md.c

@@ -5144,7 +5144,7 @@ int md_run(struct mddev *mddev)
 
 	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 
-	if (mddev->flags)
+	if (mddev->flags & MD_UPDATE_SB_FLAGS)
 		md_update_sb(mddev, 0);
 
 	md_new_event(mddev);
@@ -5289,7 +5289,7 @@ static void __md_stop_writes(struct mddev *mddev)
 	md_super_wait(mddev);
 
 	if (mddev->ro == 0 &&
-	    (!mddev->in_sync || mddev->flags)) {
+	    (!mddev->in_sync || (mddev->flags & MD_UPDATE_SB_FLAGS))) {
 		/* mark array as shutdown cleanly */
 		mddev->in_sync = 1;
 		md_update_sb(mddev, 1);
@@ -7814,7 +7814,7 @@ void md_check_recovery(struct mddev *mddev)
 				sysfs_notify_dirent_safe(mddev->sysfs_state);
 		}
 
-		if (mddev->flags)
+		if (mddev->flags & MD_UPDATE_SB_FLAGS)
 			md_update_sb(mddev, 0);
 
 		if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) &&

drivers/md/md.h

@@ -204,11 +204,12 @@ struct mddev {
 	struct md_personality		*pers;
 	dev_t				unit;
 	int				md_minor;
-	struct list_head 		disks;
+	struct list_head		disks;
 	unsigned long			flags;
 #define MD_CHANGE_DEVS	0	/* Some device status has changed */
 #define MD_CHANGE_CLEAN 1	/* transition to or from 'clean' */
 #define MD_CHANGE_PENDING 2	/* switch from 'clean' to 'active' in progress */
+#define MD_UPDATE_SB_FLAGS (1 | 2 | 4)	/* If these are set, md_update_sb needed */
 #define MD_ARRAY_FIRST_USE 3    /* First use of array, needs initialization */
 
 	int				suspended;
@@ -218,7 +219,7 @@ struct mddev {
 						       * are happening, so run/
 						       * takeover/stop are not safe
 						       */
-	int				ready; /* See when safe to pass 
+	int				ready; /* See when safe to pass
 						* IO requests down */
 	struct gendisk			*gendisk;