4 files changed, 72 insertions, 15 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index f30f09cb08e8..6cb31f8da14c 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -201,12 +201,68 @@ static DEFINE_SPINLOCK(all_mddevs_lock);
                 )
 
 
-static int md_fail_request(struct request_queue *q, struct bio *bio)
+/* Rather than calling directly into the personality make_request function,
+ * IO requests come here first so that we can check if the device is
+ * being suspended pending a reconfiguration.
+ * We hold a refcount over the call to ->make_request.  By the time that
+ * call has finished, the bio has been linked into some internal structure
+ * and so is visible to ->quiesce(), so we don't need the refcount any more.
+ */
+static int md_make_request(struct request_queue *q, struct bio *bio)
 {
-        bio_io_error(bio);
-        return 0;
+        mddev_t *mddev = q->queuedata;
+        int rv;
+        if (mddev == NULL || mddev->pers == NULL) {
+                bio_io_error(bio);
+                return 0;
+        }
+        rcu_read_lock();
+        if (mddev->suspended) {
+                DEFINE_WAIT(__wait);
+                for (;;) {
+                        prepare_to_wait(&mddev->sb_wait, &__wait,
+                                        TASK_UNINTERRUPTIBLE);
+                        if (!mddev->suspended)
+                                break;
+                        rcu_read_unlock();
+                        schedule();
+                        rcu_read_lock();
+                }
+                finish_wait(&mddev->sb_wait, &__wait);
+        }
+        atomic_inc(&mddev->active_io);
+        rcu_read_unlock();
+        rv = mddev->pers->make_request(q, bio);
+        if (atomic_dec_and_test(&mddev->active_io) && mddev->suspended)
+                wake_up(&mddev->sb_wait);
+
+        return rv;
 }
 
+static void mddev_suspend(mddev_t *mddev)
+{
+        BUG_ON(mddev->suspended);
+        mddev->suspended = 1;
+        synchronize_rcu();
+        wait_event(mddev->sb_wait, atomic_read(&mddev->active_io) == 0);
+        mddev->pers->quiesce(mddev, 1);
+        md_unregister_thread(mddev->thread);
+        mddev->thread = NULL;
+        /* we now know that no code is executing in the personality module,
+         * except possibly the tail end of a ->bi_end_io function, but that
+         * is certain to complete before the module has a chance to get
+         * unloaded
+         */
+}
+
+static void mddev_resume(mddev_t *mddev)
+{
+        mddev->suspended = 0;
+        wake_up(&mddev->sb_wait);
+        mddev->pers->quiesce(mddev, 0);
+}
+
+
 static inline mddev_t *mddev_get(mddev_t *mddev)
 {
         atomic_inc(&mddev->active);
@@ -314,6 +370,7 @@ static mddev_t * mddev_find(dev_t unit)
         init_timer(&new->safemode_timer);
         atomic_set(&new->active, 1);
         atomic_set(&new->openers, 0);
+        atomic_set(&new->active_io, 0);
         spin_lock_init(&new->write_lock);
         init_waitqueue_head(&new->sb_wait);
         init_waitqueue_head(&new->recovery_wait);
@@ -3632,10 +3689,12 @@ static int md_alloc(dev_t dev, char *name)
                 mddev_put(mddev);
                 return -ENOMEM;
         }
+        mddev->queue->queuedata = mddev;
+
         /* Can be unlocked because the queue is new: no concurrency */
         queue_flag_set_unlocked(QUEUE_FLAG_CLUSTER, mddev->queue);
 
-        blk_queue_make_request(mddev->queue, md_fail_request);
+        blk_queue_make_request(mddev->queue, md_make_request);
 
         disk = alloc_disk(1 << shift);
         if (!disk) {
@@ -3938,16 +3997,6 @@ static int do_md_run(mddev_t * mddev)
 
         set_capacity(disk, mddev->array_sectors);
 
-        /* If we call blk_queue_make_request here, it will
-         * re-initialise max_sectors etc which may have been
-         * refined inside -> run.  So just set the bits we need to set.
-         * Most initialisation happended when we called
-         * blk_queue_make_request(..., md_fail_request)
-         * earlier.
-         */
-        mddev->queue->queuedata = mddev;
-        mddev->queue->make_request_fn = mddev->pers->make_request;
-
         /* If there is a partially-recovered drive we need to
          * start recovery here.  If we leave it to md_check_recovery,
          * it will remove the drives and not do the right thing
@@ -4077,7 +4126,7 @@ static int do_md_stop(mddev_t * mddev, int mode, int is_open)
                         md_super_wait(mddev);
                         if (mddev->ro)
                                 set_disk_ro(disk, 0);
-                        blk_queue_make_request(mddev->queue, md_fail_request);
+
                         mddev->pers->stop(mddev);
                         mddev->queue->merge_bvec_fn = NULL;
                         mddev->queue->unplug_fn = NULL;
diff --git a/drivers/md/md.h b/drivers/md/md.h
index c07ea9118063..84b22d67ba14 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -119,6 +119,8 @@ struct mddev_s
 #define MD_CHANGE_CLEAN 1       /* transition to or from 'clean' */
 #define MD_CHANGE_PENDING 2     /* superblock update in progress */
 
+        int                             suspended;
+        atomic_t                        active_io;
         int                             ro;
 
         struct gendisk                  *gendisk;
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 779958705abf..7eaca3209364 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -2092,6 +2092,9 @@ static int stop(mddev_t *mddev)
                 /* need to kick something here to make sure I/O goes? */
         }
 
+        raise_barrier(conf);
+        lower_barrier(conf);
+
         md_unregister_thread(mddev->thread);
         mddev->thread = NULL;
         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index d56cb2ae515f..c2059e25d03f 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -2211,6 +2211,9 @@ static int stop(mddev_t *mddev)
 {
         conf_t *conf = mddev_to_conf(mddev);
 
+        raise_barrier(conf, 0);
+        lower_barrier(conf);
+
         md_unregister_thread(mddev->thread);
         mddev->thread = NULL;
         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/