---

yaml
---
r: 176080
b: refs/heads/master
c: a2826aa
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: efa593390e70b0e3c39f6b2dca8876b6b1461e41
+refs/heads/master: a2826aa92e2e14db372eda01d333267258944033

trunk/drivers/md/linear.c

@@ -292,7 +292,7 @@ static int linear_make_request (struct request_queue *q, struct bio *bio)
 	int cpu;
 
 	if (unlikely(bio_rw_flagged(bio, BIO_RW_BARRIER))) {
-		bio_endio(bio, -EOPNOTSUPP);
+		md_barrier_request(mddev, bio);
 		return 0;
 	}
 

trunk/drivers/md/md.c

@@ -213,12 +213,12 @@ static int md_make_request(struct request_queue *q, struct bio *bio)
 		return 0;
 	}
 	rcu_read_lock();
-	if (mddev->suspended) {
+	if (mddev->suspended || mddev->barrier) {
 		DEFINE_WAIT(__wait);
 		for (;;) {
 			prepare_to_wait(&mddev->sb_wait, &__wait,
 					TASK_UNINTERRUPTIBLE);
-			if (!mddev->suspended)
+			if (!mddev->suspended && !mddev->barrier)
 				break;
 			rcu_read_unlock();
 			schedule();
@@ -260,10 +260,110 @@ static void mddev_resume(mddev_t *mddev)
 
 int mddev_congested(mddev_t *mddev, int bits)
 {
+	if (mddev->barrier)
+		return 1;
 	return mddev->suspended;
 }
 EXPORT_SYMBOL(mddev_congested);
 
+/*
+ * Generic barrier handling for md
+ */
+
+#define POST_REQUEST_BARRIER ((void*)1)
+
+static void md_end_barrier(struct bio *bio, int err)
+{
+	mdk_rdev_t *rdev = bio->bi_private;
+	mddev_t *mddev = rdev->mddev;
+	if (err == -EOPNOTSUPP && mddev->barrier != POST_REQUEST_BARRIER)
+		set_bit(BIO_EOPNOTSUPP, &mddev->barrier->bi_flags);
+
+	rdev_dec_pending(rdev, mddev);
+
+	if (atomic_dec_and_test(&mddev->flush_pending)) {
+		if (mddev->barrier == POST_REQUEST_BARRIER) {
+			/* This was a post-request barrier */
+			mddev->barrier = NULL;
+			wake_up(&mddev->sb_wait);
+		} else
+			/* The pre-request barrier has finished */
+			schedule_work(&mddev->barrier_work);
+	}
+	bio_put(bio);
+}
+
+static void submit_barriers(mddev_t *mddev)
+{
+	mdk_rdev_t *rdev;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(rdev, &mddev->disks, same_set)
+		if (rdev->raid_disk >= 0 &&
+		    !test_bit(Faulty, &rdev->flags)) {
+			/* Take two references, one is dropped
+			 * when request finishes, one after
+			 * we reclaim rcu_read_lock
+			 */
+			struct bio *bi;
+			atomic_inc(&rdev->nr_pending);
+			atomic_inc(&rdev->nr_pending);
+			rcu_read_unlock();
+			bi = bio_alloc(GFP_KERNEL, 0);
+			bi->bi_end_io = md_end_barrier;
+			bi->bi_private = rdev;
+			bi->bi_bdev = rdev->bdev;
+			atomic_inc(&mddev->flush_pending);
+			submit_bio(WRITE_BARRIER, bi);
+			rcu_read_lock();
+			rdev_dec_pending(rdev, mddev);
+		}
+	rcu_read_unlock();
+}
+
+static void md_submit_barrier(struct work_struct *ws)
+{
+	mddev_t *mddev = container_of(ws, mddev_t, barrier_work);
+	struct bio *bio = mddev->barrier;
+
+	atomic_set(&mddev->flush_pending, 1);
+
+	if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags))
+		bio_endio(bio, -EOPNOTSUPP);
+	else if (bio->bi_size == 0)
+		/* an empty barrier - all done */
+		bio_endio(bio, 0);
+	else {
+		bio->bi_rw &= ~(1<<BIO_RW_BARRIER);
+		if (mddev->pers->make_request(mddev->queue, bio))
+			generic_make_request(bio);
+		mddev->barrier = POST_REQUEST_BARRIER;
+		submit_barriers(mddev);
+	}
+	if (atomic_dec_and_test(&mddev->flush_pending)) {
+		mddev->barrier = NULL;
+		wake_up(&mddev->sb_wait);
+	}
+}
+
+void md_barrier_request(mddev_t *mddev, struct bio *bio)
+{
+	spin_lock_irq(&mddev->write_lock);
+	wait_event_lock_irq(mddev->sb_wait,
+			    !mddev->barrier,
+			    mddev->write_lock, /*nothing*/);
+	mddev->barrier = bio;
+	spin_unlock_irq(&mddev->write_lock);
+
+	atomic_set(&mddev->flush_pending, 1);
+	INIT_WORK(&mddev->barrier_work, md_submit_barrier);
+
+	submit_barriers(mddev);
+
+	if (atomic_dec_and_test(&mddev->flush_pending))
+		schedule_work(&mddev->barrier_work);
+}
+EXPORT_SYMBOL(md_barrier_request);
 
 static inline mddev_t *mddev_get(mddev_t *mddev)
 {
@@ -371,6 +471,7 @@ static mddev_t * mddev_find(dev_t unit)
 	atomic_set(&new->openers, 0);
 	atomic_set(&new->active_io, 0);
 	spin_lock_init(&new->write_lock);
+	atomic_set(&new->flush_pending, 0);
 	init_waitqueue_head(&new->sb_wait);
 	init_waitqueue_head(&new->recovery_wait);
 	new->reshape_position = MaxSector;

trunk/drivers/md/md.h

@@ -292,6 +292,17 @@ struct mddev_s
 	struct mutex			bitmap_mutex;
 
 	struct list_head		all_mddevs;
+
+	/* Generic barrier handling.
+	 * If there is a pending barrier request, all other
+	 * writes are blocked while the devices are flushed.
+	 * The last to finish a flush schedules a worker to
+	 * submit the barrier request (without the barrier flag),
+	 * then submit more flush requests.
+	 */
+	struct bio *barrier;
+	atomic_t flush_pending;
+	struct work_struct barrier_work;
 };
 
 
@@ -432,6 +443,7 @@ extern void md_done_sync(mddev_t *mddev, int blocks, int ok);
 extern void md_error(mddev_t *mddev, mdk_rdev_t *rdev);
 
 extern int mddev_congested(mddev_t *mddev, int bits);
+extern void md_barrier_request(mddev_t *mddev, struct bio *bio);
 extern void md_super_write(mddev_t *mddev, mdk_rdev_t *rdev,
 			   sector_t sector, int size, struct page *page);
 extern void md_super_wait(mddev_t *mddev);

trunk/drivers/md/multipath.c

@@ -145,7 +145,7 @@ static int multipath_make_request (struct request_queue *q, struct bio * bio)
 	int cpu;
 
 	if (unlikely(bio_rw_flagged(bio, BIO_RW_BARRIER))) {
-		bio_endio(bio, -EOPNOTSUPP);
+		md_barrier_request(mddev, bio);
 		return 0;
 	}
 

trunk/drivers/md/raid0.c

@@ -453,7 +453,7 @@ static int raid0_make_request(struct request_queue *q, struct bio *bio)
 	int cpu;
 
 	if (unlikely(bio_rw_flagged(bio, BIO_RW_BARRIER))) {
-		bio_endio(bio, -EOPNOTSUPP);
+		md_barrier_request(mddev, bio);
 		return 0;
 	}
 

trunk/drivers/md/raid10.c

@@ -804,7 +804,7 @@ static int make_request(struct request_queue *q, struct bio * bio)
 	mdk_rdev_t *blocked_rdev;
 
 	if (unlikely(bio_rw_flagged(bio, BIO_RW_BARRIER))) {
-		bio_endio(bio, -EOPNOTSUPP);
+		md_barrier_request(mddev, bio);
 		return 0;
 	}
 

trunk/drivers/md/raid5.c

@@ -3865,7 +3865,13 @@ static int make_request(struct request_queue *q, struct bio * bi)
 	int cpu, remaining;
 
 	if (unlikely(bio_rw_flagged(bi, BIO_RW_BARRIER))) {
-		bio_endio(bi, -EOPNOTSUPP);
+		/* Drain all pending writes.  We only really need
+		 * to ensure they have been submitted, but this is
+		 * easier.
+		 */
+		mddev->pers->quiesce(mddev, 1);
+		mddev->pers->quiesce(mddev, 0);
+		md_barrier_request(mddev, bi);
 		return 0;
 	}