Merge branch 'for-4.6/drivers' of git://git.kernel.dk/linux-block

Pull block driver updates from Jens Axboe:
 "This is the block driver pull request for this merge window.  It sits
  on top of for-4.6/core, that was just sent out.

  This contains:

   - A set of fixes for lightnvm.  One from Alan, fixing an overflow,
     and the rest from the usual suspects, Javier and Matias.

   - A set of fixes for nbd from Markus and Dan, and a fixup from Arnd
     for correct usage of the signed 64-bit divider.

   - A set of bug fixes for the Micron mtip32xx, from Asai.

   - A fix for the brd discard handling from Bart.

   - Update the maintainers entry for cciss, since that hardware has
     transferred ownership.

   - Three bug fixes for bcache from Eric Wheeler.

   - Set of fixes for xen-blk{back,front} from Jan and Konrad.

   - Removal of the cpqarray driver.  It has been disabled in Kconfig
     since 2013, and we were initially scheduled to remove it in 3.15.

   - Various updates and fixes for NVMe, with the most important being:

        - Removal of the per-device NVMe thread, replacing that with a
          watchdog timer instead. From Christoph.

        - Exposing the namespace WWID through sysfs, from Keith.

        - Set of cleanups from Ming Lin.

        - Logging the controller device name instead of the underlying
          PCI device name, from Sagi.

        - And a bunch of fixes and optimizations from the usual suspects
          in this area"

* 'for-4.6/drivers' of git://git.kernel.dk/linux-block: (49 commits)
  NVMe: Expose ns wwid through single sysfs entry
  drivers:block: cpqarray clean up
  brd: Fix discard request processing
  cpqarray: remove it from the kernel
  cciss: update MAINTAINERS
  NVMe: Remove unused sq_head read in completion path
  bcache: fix cache_set_flush() NULL pointer dereference on OOM
  bcache: cleaned up error handling around register_cache()
  bcache: fix race of writeback thread starting before complete initialization
  NVMe: Create discard zero quirk white list
  nbd: use correct div_s64 helper
  mtip32xx: remove unneeded variable in mtip_cmd_timeout()
  lightnvm: generalize rrpc ppa calculations
  lightnvm: remove struct nvm_dev->total_blocks
  lightnvm: rename ->nr_pages to ->nr_sects
  lightnvm: update closed list outside of intr context
  xen/blback: Fit the important information of the thread in 17 characters
  lightnvm: fold get bb tbl when using dual/quad plane mode
  lightnvm: fix up nonsensical configure overrun checking
  xen-blkback: advertise indirect segment support earlier
  ...

drivers/md/bcache/super.c

@@ -1015,8 +1015,12 @@ int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c)
 	 */
 	atomic_set(&dc->count, 1);
 
-	if (bch_cached_dev_writeback_start(dc))
+	/* Block writeback thread, but spawn it */
+	down_write(&dc->writeback_lock);
+	if (bch_cached_dev_writeback_start(dc)) {
+		up_write(&dc->writeback_lock);
 		return -ENOMEM;
+	}
 
 	if (BDEV_STATE(&dc->sb) == BDEV_STATE_DIRTY) {
 		bch_sectors_dirty_init(dc);
@@ -1028,6 +1032,9 @@ int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c)
 	bch_cached_dev_run(dc);
 	bcache_device_link(&dc->disk, c, "bdev");
 
+	/* Allow the writeback thread to proceed */
+	up_write(&dc->writeback_lock);
+
 	pr_info("Caching %s as %s on set %pU",
 		bdevname(dc->bdev, buf), dc->disk.disk->disk_name,
 		dc->disk.c->sb.set_uuid);
@@ -1366,6 +1373,9 @@ static void cache_set_flush(struct closure *cl)
 	struct btree *b;
 	unsigned i;
 
+	if (!c)
+		closure_return(cl);
+
 	bch_cache_accounting_destroy(&c->accounting);
 
 	kobject_put(&c->internal);
@@ -1828,11 +1838,12 @@ static int cache_alloc(struct cache_sb *sb, struct cache *ca)
 	return 0;
 }
 
-static void register_cache(struct cache_sb *sb, struct page *sb_page,
+static int register_cache(struct cache_sb *sb, struct page *sb_page,
 				struct block_device *bdev, struct cache *ca)
 {
 	char name[BDEVNAME_SIZE];
-	const char *err = "cannot allocate memory";
+	const char *err = NULL;
+	int ret = 0;
 
 	memcpy(&ca->sb, sb, sizeof(struct cache_sb));
 	ca->bdev = bdev;
@@ -1847,27 +1858,35 @@ static void register_cache(struct cache_sb *sb, struct page *sb_page,
 	if (blk_queue_discard(bdev_get_queue(ca->bdev)))
 		ca->discard = CACHE_DISCARD(&ca->sb);
 
-	if (cache_alloc(sb, ca) != 0)
+	ret = cache_alloc(sb, ca);
+	if (ret != 0)
 		goto err;
 
-	err = "error creating kobject";
-	if (kobject_add(&ca->kobj, &part_to_dev(bdev->bd_part)->kobj, "bcache"))
-		goto err;
+	if (kobject_add(&ca->kobj, &part_to_dev(bdev->bd_part)->kobj, "bcache")) {
+		err = "error calling kobject_add";
+		ret = -ENOMEM;
+		goto out;
+	}
 
 	mutex_lock(&bch_register_lock);
 	err = register_cache_set(ca);
 	mutex_unlock(&bch_register_lock);
 
-	if (err)
-		goto err;
+	if (err) {
+		ret = -ENODEV;
+		goto out;
+	}
 
 	pr_info("registered cache device %s", bdevname(bdev, name));
+
 out:
 	kobject_put(&ca->kobj);
-	return;
+
 err:
-	pr_notice("error opening %s: %s", bdevname(bdev, name), err);
-	goto out;
+	if (err)
+		pr_notice("error opening %s: %s", bdevname(bdev, name), err);
+
+	return ret;
 }
 
 /* Global interfaces/init */
@@ -1965,7 +1984,8 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 		if (!ca)
 			goto err_close;
 
-		register_cache(sb, sb_page, bdev, ca);
+		if (register_cache(sb, sb_page, bdev, ca) != 0)
+			goto err_close;
 	}
 out:
 	if (sb_page)