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>

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index ae187e5d7d5892b21111966aee4f8acdb4998194..030bc2a053ec98e15c8afe06a10a5251f5e61625 100644 (file)
--- 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);
 }