md: Better control of when do_md_stop is allowed to stop the array.

do_md_stop check the number of active users before allowing the array
to be stopped.
Two problems:
  1/ it assumes the request is coming through an open file descriptor
     (via ioctl) so it allows for that.  This is not always the case.
  2/ it doesn't do the check it the array hasn't been activated.
     This is not good for cases when we use an inactive array to hold
     some devices in a container.

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

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 328e247..4c4c79d 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -2688,7 +2688,7 @@ array_state_show(mddev_t *mddev, char *page)
        return sprintf(page, "%s\n", array_states[st]);
 }
 
-static int do_md_stop(mddev_t * mddev, int ro);
+static int do_md_stop(mddev_t * mddev, int ro, int is_open);
 static int do_md_run(mddev_t * mddev);
 static int restart_array(mddev_t *mddev);
 
@@ -2704,14 +2704,14 @@ array_state_store(mddev_t *mddev, const char *buf, size_t len)
                /* stopping an active array */
                if (atomic_read(&mddev->active) > 1)
                        return -EBUSY;
-               err = do_md_stop(mddev, 0);
+               err = do_md_stop(mddev, 0, 0);
                break;
        case inactive:
                /* stopping an active array */
                if (mddev->pers) {
                        if (atomic_read(&mddev->active) > 1)
                                return -EBUSY;
-                       err = do_md_stop(mddev, 2);
+                       err = do_md_stop(mddev, 2, 0);
                } else
                        err = 0; /* already inactive */
                break;
@@ -2719,7 +2719,7 @@ array_state_store(mddev_t *mddev, const char *buf, size_t len)
                break; /* not supported yet */
        case readonly:
                if (mddev->pers)
-                       err = do_md_stop(mddev, 1);
+                       err = do_md_stop(mddev, 1, 0);
                else {
                        mddev->ro = 1;
                        set_disk_ro(mddev->gendisk, 1);
@@ -2729,7 +2729,7 @@ array_state_store(mddev_t *mddev, const char *buf, size_t len)
        case read_auto:
                if (mddev->pers) {
                        if (mddev->ro != 1)
-                               err = do_md_stop(mddev, 1);
+                               err = do_md_stop(mddev, 1, 0);
                        else
                                err = restart_array(mddev);
                        if (err == 0) {
@@ -3818,16 +3818,17 @@ static void restore_bitmap_write_access(struct file *file)
  *   1 - switch to readonly
  *   2 - stop but do not disassemble array
  */
-static int do_md_stop(mddev_t * mddev, int mode)
+static int do_md_stop(mddev_t * mddev, int mode, int is_open)
 {
        int err = 0;
        struct gendisk *disk = mddev->gendisk;
 
+       if (atomic_read(&mddev->active) > 1 + is_open) {
+               printk("md: %s still in use.\n",mdname(mddev));
+               return -EBUSY;
+       }
+
        if (mddev->pers) {
-               if (atomic_read(&mddev->active)>2) {
-                       printk("md: %s still in use.\n",mdname(mddev));
-                       return -EBUSY;
-               }
 
                if (mddev->sync_thread) {
                        set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
@@ -3976,7 +3977,7 @@ static void autorun_array(mddev_t *mddev)
        err = do_md_run (mddev);
        if (err) {
                printk(KERN_WARNING "md: do_md_run() returned %d\n", err);
-               do_md_stop (mddev, 0);
+               do_md_stop (mddev, 0, 0);
        }
 }
 
@@ -4931,11 +4932,11 @@ static int md_ioctl(struct inode *inode, struct file *file,
                        goto done_unlock;
 
                case STOP_ARRAY:
-                       err = do_md_stop (mddev, 0);
+                       err = do_md_stop (mddev, 0, 1);
                        goto done_unlock;
 
                case STOP_ARRAY_RO:
-                       err = do_md_stop (mddev, 1);
+                       err = do_md_stop (mddev, 1, 1);
                        goto done_unlock;
 
        }
@@ -6226,7 +6227,7 @@ static int md_notify_reboot(struct notifier_block *this,
 
                for_each_mddev(mddev, tmp)
                        if (mddev_trylock(mddev)) {
-                               do_md_stop (mddev, 1);
+                               do_md_stop (mddev, 1, 0);
                                mddev_unlock(mddev);
                        }
                /*