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

Pull block fixes from Jens Axboe:
 "Sending this a bit sooner than I otherwise would have, as a fix in the
  merge window had some unfortunate issues and side effects for some
  folks.

  This contains:

   - Fixes from Jan for the bdi registration/unregistration. These have
     been tested by the various parties reporting issues, and should be
     solid at this point.

   - Also from Jan, fix for axonram gendisk registration.

   - A stable fix for zram from Johannes.

   - A small series from Ming, fixing up some long standing issues with
     blk-mq hardware queue kobject initialization and registration.

   - A fix for sed opal from Jon, fixing a nonsensical range check and
     some set-but-not-used variables.

   - A fix from Neil for a long standing deadlock issue for stacking
     device drivers. With this in place, dm/md don't have to work around
     the issue anymore, and can be properly fixed up"

* 'for-linus' of git://git.kernel.dk/linux-block:
  axonram: Fix gendisk handling
  blk: improve order of bio handling in generic_make_request()
  Revert "scsi, block: fix duplicate bdi name registration crashes"
  block: Make del_gendisk() safer for disks without queues
  bdi: Fix use-after-free in wb_congested_put()
  block: Allow bdi re-registration
  block/sed: Fix opal user range check and unused variables
  zram: set physical queue limits to avoid array out of bounds accesses
  blk-mq: free hctx->cpumask in release handler of hctx's kobject
  blk-mq: make lifetime consistent between hctx and its kobject
  blk-mq: make lifetime consitent between q/ctx and its kobject
  blk-mq: initialize mq kobjects in blk_mq_init_allocated_queue()

1 files changed, 28 insertions, 15 deletions

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 6d861d0..c6f2a37 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -683,33 +683,26 @@ static int cgwb_bdi_init(struct backing_dev_info *bdi)
 static void cgwb_bdi_destroy(struct backing_dev_info *bdi)
 {
 	struct radix_tree_iter iter;
-	struct rb_node *rbn;
 	void **slot;
 
 	WARN_ON(test_bit(WB_registered, &bdi->wb.state));
 
 	spin_lock_irq(&cgwb_lock);
-
 	radix_tree_for_each_slot(slot, &bdi->cgwb_tree, &iter, 0)
 		cgwb_kill(*slot);
-
-	while ((rbn = rb_first(&bdi->cgwb_congested_tree))) {
-		struct bdi_writeback_congested *congested =
-			rb_entry(rbn, struct bdi_writeback_congested, rb_node);
-
-		rb_erase(rbn, &bdi->cgwb_congested_tree);
-		congested->bdi = NULL;	/* mark @congested unlinked */
-	}
-
 	spin_unlock_irq(&cgwb_lock);
 
 	/*
-	 * All cgwb's and their congested states must be shutdown and
-	 * released before returning.  Drain the usage counter to wait for
-	 * all cgwb's and cgwb_congested's ever created on @bdi.
+	 * All cgwb's must be shutdown and released before returning.  Drain
+	 * the usage counter to wait for all cgwb's ever created on @bdi.
 	 */
 	atomic_dec(&bdi->usage_cnt);
 	wait_event(cgwb_release_wait, !atomic_read(&bdi->usage_cnt));
+	/*
+	 * Grab back our reference so that we hold it when @bdi gets
+	 * re-registered.
+	 */
+	atomic_inc(&bdi->usage_cnt);
 }
 
 /**
@@ -749,6 +742,21 @@ void wb_blkcg_offline(struct blkcg *blkcg)
 	spin_unlock_irq(&cgwb_lock);
 }
 
+static void cgwb_bdi_exit(struct backing_dev_info *bdi)
+{
+	struct rb_node *rbn;
+
+	spin_lock_irq(&cgwb_lock);
+	while ((rbn = rb_first(&bdi->cgwb_congested_tree))) {
+		struct bdi_writeback_congested *congested =
+			rb_entry(rbn, struct bdi_writeback_congested, rb_node);
+
+		rb_erase(rbn, &bdi->cgwb_congested_tree);
+		congested->bdi = NULL;	/* mark @congested unlinked */
+	}
+	spin_unlock_irq(&cgwb_lock);
+}
+
 #else	/* CONFIG_CGROUP_WRITEBACK */
 
 static int cgwb_bdi_init(struct backing_dev_info *bdi)
@@ -769,7 +777,9 @@ static int cgwb_bdi_init(struct backing_dev_info *bdi)
 	return 0;
 }
 
-static void cgwb_bdi_destroy(struct backing_dev_info *bdi)
+static void cgwb_bdi_destroy(struct backing_dev_info *bdi) { }
+
+static void cgwb_bdi_exit(struct backing_dev_info *bdi)
 {
 	wb_congested_put(bdi->wb_congested);
 }
@@ -857,6 +867,8 @@ int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner)
 			MINOR(owner->devt));
 	if (rc)
 		return rc;
+	/* Leaking owner reference... */
+	WARN_ON(bdi->owner);
 	bdi->owner = owner;
 	get_device(owner);
 	return 0;
@@ -898,6 +910,7 @@ static void bdi_exit(struct backing_dev_info *bdi)
 {
 	WARN_ON_ONCE(bdi->dev);
 	wb_exit(&bdi->wb);
+	cgwb_bdi_exit(bdi);
 }
 
 static void release_bdi(struct kref *ref)