dm mpath: add mutex to synchronize adding and flushing work

Add a mutex to allow possible creators of new work to synchronize with
flushing work queues.

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 5b23f2d..700154e 100644 (file)
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -93,6 +93,8 @@ struct multipath {
         * can resubmit bios on error.
         */
        mempool_t *mpio_pool;
+
+       struct mutex work_mutex;
 };
 
 /*
@@ -198,6 +200,7 @@ static struct multipath *alloc_multipath(struct dm_target *ti)
                m->queue_io = 1;
                INIT_WORK(&m->process_queued_ios, process_queued_ios);
                INIT_WORK(&m->trigger_event, trigger_event);
+               mutex_init(&m->work_mutex);
                m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache);
                if (!m->mpio_pool) {
                        kfree(m);
@@ -1268,7 +1271,11 @@ static void multipath_presuspend(struct dm_target *ti)
 
 static void multipath_postsuspend(struct dm_target *ti)
 {
+       struct multipath *m = ti->private;
+
+       mutex_lock(&m->work_mutex);
        flush_multipath_work();
+       mutex_unlock(&m->work_mutex);
 }
 
 /*
@@ -1407,51 +1414,61 @@ static int multipath_status(struct dm_target *ti, status_type_t type,
 
 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
 {
-       int r;
+       int r = -EINVAL;
        struct dm_dev *dev;
        struct multipath *m = (struct multipath *) ti->private;
        action_fn action;
 
+       mutex_lock(&m->work_mutex);
+
        if (argc == 1) {
-               if (!strnicmp(argv[0], MESG_STR("queue_if_no_path")))
-                       return queue_if_no_path(m, 1, 0);
-               else if (!strnicmp(argv[0], MESG_STR("fail_if_no_path")))
-                       return queue_if_no_path(m, 0, 0);
+               if (!strnicmp(argv[0], MESG_STR("queue_if_no_path"))) {
+                       r = queue_if_no_path(m, 1, 0);
+                       goto out;
+               } else if (!strnicmp(argv[0], MESG_STR("fail_if_no_path"))) {
+                       r = queue_if_no_path(m, 0, 0);
+                       goto out;
+               }
        }
 
-       if (argc != 2)
-               goto error;
+       if (argc != 2) {
+               DMWARN("Unrecognised multipath message received.");
+               goto out;
+       }
 
-       if (!strnicmp(argv[0], MESG_STR("disable_group")))
-               return bypass_pg_num(m, argv[1], 1);
-       else if (!strnicmp(argv[0], MESG_STR("enable_group")))
-               return bypass_pg_num(m, argv[1], 0);
-       else if (!strnicmp(argv[0], MESG_STR("switch_group")))
-               return switch_pg_num(m, argv[1]);
-       else if (!strnicmp(argv[0], MESG_STR("reinstate_path")))
+       if (!strnicmp(argv[0], MESG_STR("disable_group"))) {
+               r = bypass_pg_num(m, argv[1], 1);
+               goto out;
+       } else if (!strnicmp(argv[0], MESG_STR("enable_group"))) {
+               r = bypass_pg_num(m, argv[1], 0);
+               goto out;
+       } else if (!strnicmp(argv[0], MESG_STR("switch_group"))) {
+               r = switch_pg_num(m, argv[1]);
+               goto out;
+       } else if (!strnicmp(argv[0], MESG_STR("reinstate_path")))
                action = reinstate_path;
        else if (!strnicmp(argv[0], MESG_STR("fail_path")))
                action = fail_path;
-       else
-               goto error;
+       else {
+               DMWARN("Unrecognised multipath message received.");
+               goto out;
+       }
 
        r = dm_get_device(ti, argv[1], ti->begin, ti->len,
                          dm_table_get_mode(ti->table), &dev);
        if (r) {
                DMWARN("message: error getting device %s",
                       argv[1]);
-               return -EINVAL;
+               goto out;
        }
 
        r = action_dev(m, dev, action);
 
        dm_put_device(ti, dev);
 
+out:
+       mutex_unlock(&m->work_mutex);
        return r;
-
-error:
-       DMWARN("Unrecognised multipath message received.");
-       return -EINVAL;
 }
 
 static int multipath_ioctl(struct dm_target *ti, unsigned int cmd,