dm mpath: prevent io from work queue while suspended

Reject messages that can generate I/O while the device itself
is suspended.

Signed-off-by: Mike Anderson <andmike@linux.vnet.ibm.com>
Acked-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 700154e21483..45d9bf14cc48 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -95,6 +95,8 @@ struct multipath {
         mempool_t *mpio_pool;
 
         struct mutex work_mutex;
+
+        unsigned suspended;     /* Don't create new I/O internally when set. */
 };
 
 /*
@@ -1274,6 +1276,7 @@ static void multipath_postsuspend(struct dm_target *ti)
         struct multipath *m = ti->private;
 
         mutex_lock(&m->work_mutex);
+        m->suspended = 1;
         flush_multipath_work();
         mutex_unlock(&m->work_mutex);
 }
@@ -1286,6 +1289,10 @@ static void multipath_resume(struct dm_target *ti)
         struct multipath *m = (struct multipath *) ti->private;
         unsigned long flags;
 
+        mutex_lock(&m->work_mutex);
+        m->suspended = 0;
+        mutex_unlock(&m->work_mutex);
+
         spin_lock_irqsave(&m->lock, flags);
         m->queue_if_no_path = m->saved_queue_if_no_path;
         spin_unlock_irqrestore(&m->lock, flags);
@@ -1421,6 +1428,11 @@ static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
 
         mutex_lock(&m->work_mutex);
 
+        if (m->suspended) {
+                r = -EBUSY;
+                goto out;
+        }
+
         if (argc == 1) {
                 if (!strnicmp(argv[0], MESG_STR("queue_if_no_path"))) {
                         r = queue_if_no_path(m, 1, 0);