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>

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 700154e..45d9bf1 100644 (file)
--- 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);