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

Pull block fixes from Jens Axboe:
 "A small collection of fixes/changes for the current series.  This
  contains:

   - Removal of dead code from Gu Zheng.

   - Revert of two bad fixes that went in earlier in this round, marking
     things as __init that were not purely used from init.

   - A fix for blk_mq_start_hw_queue() using the __blk_mq_run_hw_queue(),
     which could place us wrongly.  Make it use the non __ variant,
     which handles cases where we are called from the wrong CPU set.
     From me.

   - A fix for drbd, which allocates discard requests without room for
     the SCSI payload.  From Lars Ellenberg.

   - A fix for user-after-free in the blkcg code from Tejun.

   - Addition of limiting gaps in SG lists, if the hardware needs it.
     This is the last pre-req patch for blk-mq to enable the full NVMe
     conversion.  Could wait until 3.17, but it's simple enough so would
     be nice to have everything we need for the NVMe port in the 3.17
     release.  From me"

* 'for-linus' of git://git.kernel.dk/linux-block:
  drbd: fix NULL pointer deref in blk_add_request_payload
  blk-mq: blk_mq_start_hw_queue() should use blk_mq_run_hw_queue()
  block: add support for limiting gaps in SG lists
  bio: remove unused macro bip_vec_idx()
  Revert "block: add __init to elv_register"
  Revert "block: add __init to blkcg_policy_register"
  blkcg: fix use-after-free in __blkg_release_rcu() by making blkcg_gq refcnt an atomic_t
  floppy: format block0 read error message properly

6 files changed, 32 insertions, 20 deletions

diff --git a/block/bio.c b/block/bio.c
index 8c2e55e39a1b..0ec61c9e536c 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -746,6 +746,14 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page
 
 			goto done;
 		}
+
+		/*
+		 * If the queue doesn't support SG gaps and adding this
+		 * offset would create a gap, disallow it.
+		 */
+		if (q->queue_flags & (1 << QUEUE_FLAG_SG_GAPS) &&
+		    bvec_gap_to_prev(prev, offset))
+			return 0;
 	}
 
 	if (bio->bi_vcnt >= bio->bi_max_vecs)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 069bc202ffe3..b9f4cc494ece 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -80,7 +80,7 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q,
 	blkg->q = q;
 	INIT_LIST_HEAD(&blkg->q_node);
 	blkg->blkcg = blkcg;
-	blkg->refcnt = 1;
+	atomic_set(&blkg->refcnt, 1);
 
 	/* root blkg uses @q->root_rl, init rl only for !root blkgs */
 	if (blkcg != &blkcg_root) {
@@ -399,11 +399,8 @@ void __blkg_release_rcu(struct rcu_head *rcu_head)
 
 	/* release the blkcg and parent blkg refs this blkg has been holding */
 	css_put(&blkg->blkcg->css);
-	if (blkg->parent) {
-		spin_lock_irq(blkg->q->queue_lock);
+	if (blkg->parent)
 		blkg_put(blkg->parent);
-		spin_unlock_irq(blkg->q->queue_lock);
-	}
 
 	blkg_free(blkg);
 }
@@ -1093,7 +1090,7 @@ EXPORT_SYMBOL_GPL(blkcg_deactivate_policy);
  * Register @pol with blkcg core.  Might sleep and @pol may be modified on
  * successful registration.  Returns 0 on success and -errno on failure.
  */
-int __init blkcg_policy_register(struct blkcg_policy *pol)
+int blkcg_policy_register(struct blkcg_policy *pol)
 {
 	int i, ret;
 
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index cbb7f943f78a..d3fd7aa3d2a3 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -18,6 +18,7 @@
 #include <linux/seq_file.h>
 #include <linux/radix-tree.h>
 #include <linux/blkdev.h>
+#include <linux/atomic.h>
 
 /* Max limits for throttle policy */
 #define THROTL_IOPS_MAX		UINT_MAX
@@ -104,7 +105,7 @@ struct blkcg_gq {
 	struct request_list		rl;
 
 	/* reference count */
-	int				refcnt;
+	atomic_t			refcnt;
 
 	/* is this blkg online? protected by both blkcg and q locks */
 	bool				online;
@@ -145,7 +146,7 @@ void blkcg_drain_queue(struct request_queue *q);
 void blkcg_exit_queue(struct request_queue *q);
 
 /* Blkio controller policy registration */
-int __init blkcg_policy_register(struct blkcg_policy *pol);
+int blkcg_policy_register(struct blkcg_policy *pol);
 void blkcg_policy_unregister(struct blkcg_policy *pol);
 int blkcg_activate_policy(struct request_queue *q,
 			  const struct blkcg_policy *pol);
@@ -257,13 +258,12 @@ static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
  * blkg_get - get a blkg reference
  * @blkg: blkg to get
  *
- * The caller should be holding queue_lock and an existing reference.
+ * The caller should be holding an existing reference.
  */
 static inline void blkg_get(struct blkcg_gq *blkg)
 {
-	lockdep_assert_held(blkg->q->queue_lock);
-	WARN_ON_ONCE(!blkg->refcnt);
-	blkg->refcnt++;
+	WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0);
+	atomic_inc(&blkg->refcnt);
 }
 
 void __blkg_release_rcu(struct rcu_head *rcu);
@@ -271,14 +271,11 @@ void __blkg_release_rcu(struct rcu_head *rcu);
 /**
  * blkg_put - put a blkg reference
  * @blkg: blkg to put
- *
- * The caller should be holding queue_lock.
  */
 static inline void blkg_put(struct blkcg_gq *blkg)
 {
-	lockdep_assert_held(blkg->q->queue_lock);
-	WARN_ON_ONCE(blkg->refcnt <= 0);
-	if (!--blkg->refcnt)
+	WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0);
+	if (atomic_dec_and_test(&blkg->refcnt))
 		call_rcu(&blkg->rcu_head, __blkg_release_rcu);
 }
 
@@ -580,7 +577,7 @@ static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { ret
 static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
 static inline void blkcg_drain_queue(struct request_queue *q) { }
 static inline void blkcg_exit_queue(struct request_queue *q) { }
-static inline int __init blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
+static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
 static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
 static inline int blkcg_activate_policy(struct request_queue *q,
 					const struct blkcg_policy *pol) { return 0; }
diff --git a/block/blk-merge.c b/block/blk-merge.c
index b3bf0df0f4c2..54535831f1e1 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -568,6 +568,8 @@ int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
 
 bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
 {
+	struct request_queue *q = rq->q;
+
 	if (!rq_mergeable(rq) || !bio_mergeable(bio))
 		return false;
 
@@ -591,6 +593,14 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
 	    !blk_write_same_mergeable(rq->bio, bio))
 		return false;
 
+	if (q->queue_flags & (1 << QUEUE_FLAG_SG_GAPS)) {
+		struct bio_vec *bprev;
+
+		bprev = &rq->biotail->bi_io_vec[bio->bi_vcnt - 1];
+		if (bvec_gap_to_prev(bprev, bio->bi_io_vec[0].bv_offset))
+			return false;
+	}
+
 	return true;
 }
 
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 0ef2dc7f01bf..ad69ef657e85 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -878,7 +878,7 @@ void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
 	clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
 
 	preempt_disable();
-	__blk_mq_run_hw_queue(hctx);
+	blk_mq_run_hw_queue(hctx, false);
 	preempt_enable();
 }
 EXPORT_SYMBOL(blk_mq_start_hw_queue);
diff --git a/block/elevator.c b/block/elevator.c
index 34bded18910e..24c28b659bb3 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -825,7 +825,7 @@ void elv_unregister_queue(struct request_queue *q)
 }
 EXPORT_SYMBOL(elv_unregister_queue);
 
-int __init elv_register(struct elevator_type *e)
+int elv_register(struct elevator_type *e)
 {
 	char *def = "";