dm mpath: wait for pg_init completion when suspending

When suspending the device we must wait for all I/O to complete, but
pg-init may be still in progress even after flushing the workqueue
for kmpath_handlerd in multipath_postsuspend.

This patch waits for pg-init completion correctly in
multipath_postsuspend().

Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 35 insertions, 3 deletions

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index ae187e5d7d58..030bc2a053ec 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -69,6 +69,7 @@ struct multipath {
         struct list_head priority_groups;
         unsigned pg_init_required;      /* pg_init needs calling? */
         unsigned pg_init_in_progress;   /* Only one pg_init allowed at once */
+        wait_queue_head_t pg_init_wait; /* Wait for pg_init completion */
 
         unsigned nr_valid_paths;        /* Total number of usable paths */
         struct pgpath *current_pgpath;
@@ -200,6 +201,7 @@ 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);
+                init_waitqueue_head(&m->pg_init_wait);
                 mutex_init(&m->work_mutex);
                 m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache);
                 if (!m->mpio_pool) {
@@ -891,9 +893,34 @@ static int multipath_ctr(struct dm_target *ti, unsigned int argc,
         return r;
 }
 
-static void flush_multipath_work(void)
+static void multipath_wait_for_pg_init_completion(struct multipath *m)
+{
+        DECLARE_WAITQUEUE(wait, current);
+        unsigned long flags;
+
+        add_wait_queue(&m->pg_init_wait, &wait);
+
+        while (1) {
+                set_current_state(TASK_UNINTERRUPTIBLE);
+
+                spin_lock_irqsave(&m->lock, flags);
+                if (!m->pg_init_in_progress) {
+                        spin_unlock_irqrestore(&m->lock, flags);
+                        break;
+                }
+                spin_unlock_irqrestore(&m->lock, flags);
+
+                io_schedule();
+        }
+        set_current_state(TASK_RUNNING);
+
+        remove_wait_queue(&m->pg_init_wait, &wait);
+}
+
+static void flush_multipath_work(struct multipath *m)
 {
         flush_workqueue(kmpath_handlerd);
+        multipath_wait_for_pg_init_completion(m);
         flush_workqueue(kmultipathd);
         flush_scheduled_work();
 }
@@ -902,7 +929,7 @@ static void multipath_dtr(struct dm_target *ti)
 {
         struct multipath *m = ti->private;
 
-        flush_multipath_work();
+        flush_multipath_work(m);
         free_multipath(m);
 }
 
@@ -1193,6 +1220,11 @@ static void pg_init_done(void *data, int errors)
 
         queue_work(kmultipathd, &m->process_queued_ios);
 
+        /*
+         * Wake up any thread waiting to suspend.
+         */
+        wake_up(&m->pg_init_wait);
+
 out:
         spin_unlock_irqrestore(&m->lock, flags);
 }
@@ -1281,7 +1313,7 @@ static void multipath_postsuspend(struct dm_target *ti)
         struct multipath *m = ti->private;
 
         mutex_lock(&m->work_mutex);
-        flush_multipath_work();
+        flush_multipath_work(m);
         mutex_unlock(&m->work_mutex);
 }