Merge branch 'for-3.5/core' of git://git.kernel.dk/linux-block

Merge block/IO core bits from Jens Axboe:
 "This is a bit bigger on the core side than usual, but that is purely
  because we decided to hold off on parts of Tejun's submission on 3.4
  to give it a bit more time to simmer.  As a consequence, it's seen a
  long cycle in for-next.

  It contains:

   - Bug fix from Dan, wrong locking type.
   - Relax splice gifting restriction from Eric.
   - A ton of updates from Tejun, primarily for blkcg.  This improves
     the code a lot, making the API nicer and cleaner, and also includes
     fixes for how we handle and tie policies and re-activate on
     switches.  The changes also include generic bug fixes.
   - A simple fix from Vivek, along with a fix for doing proper delayed
     allocation of the blkcg stats."

Fix up annoying conflict just due to different merge resolution in
Documentation/feature-removal-schedule.txt

* 'for-3.5/core' of git://git.kernel.dk/linux-block: (92 commits)
  blkcg: tg_stats_alloc_lock is an irq lock
  vmsplice: relax alignement requirements for SPLICE_F_GIFT
  blkcg: use radix tree to index blkgs from blkcg
  blkcg: fix blkcg->css ref leak in __blkg_lookup_create()
  block: fix elvpriv allocation failure handling
  block: collapse blk_alloc_request() into get_request()
  blkcg: collapse blkcg_policy_ops into blkcg_policy
  blkcg: embed struct blkg_policy_data in policy specific data
  blkcg: mass rename of blkcg API
  blkcg: style cleanups for blk-cgroup.h
  blkcg: remove blkio_group->path[]
  blkcg: blkg_rwstat_read() was missing inline
  blkcg: shoot down blkgs if all policies are deactivated
  blkcg: drop stuff unused after per-queue policy activation update
  blkcg: implement per-queue policy activation
  blkcg: add request_queue->root_blkg
  blkcg: make request_queue bypassing on allocation
  blkcg: make sure blkg_lookup() returns %NULL if @q is bypassing
  blkcg: make blkg_conf_prep() take @pol and return with queue lock held
  blkcg: remove static policy ID enums
  ...

1 files changed, 35 insertions, 91 deletions

diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index fb95dd2..1e2d53b 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -155,20 +155,20 @@ void put_io_context(struct io_context *ioc)
 }
 EXPORT_SYMBOL(put_io_context);
 
-/* Called by the exiting task */
-void exit_io_context(struct task_struct *task)
+/**
+ * put_io_context_active - put active reference on ioc
+ * @ioc: ioc of interest
+ *
+ * Undo get_io_context_active().  If active reference reaches zero after
+ * put, @ioc can never issue further IOs and ioscheds are notified.
+ */
+void put_io_context_active(struct io_context *ioc)
 {
-	struct io_context *ioc;
-	struct io_cq *icq;
 	struct hlist_node *n;
 	unsigned long flags;
+	struct io_cq *icq;
 
-	task_lock(task);
-	ioc = task->io_context;
-	task->io_context = NULL;
-	task_unlock(task);
-
-	if (!atomic_dec_and_test(&ioc->nr_tasks)) {
+	if (!atomic_dec_and_test(&ioc->active_ref)) {
 		put_io_context(ioc);
 		return;
 	}
@@ -197,6 +197,20 @@ retry:
 	put_io_context(ioc);
 }
 
+/* Called by the exiting task */
+void exit_io_context(struct task_struct *task)
+{
+	struct io_context *ioc;
+
+	task_lock(task);
+	ioc = task->io_context;
+	task->io_context = NULL;
+	task_unlock(task);
+
+	atomic_dec(&ioc->nr_tasks);
+	put_io_context_active(ioc);
+}
+
 /**
  * ioc_clear_queue - break any ioc association with the specified queue
  * @q: request_queue being cleared
@@ -218,19 +232,18 @@ void ioc_clear_queue(struct request_queue *q)
 	}
 }
 
-void create_io_context_slowpath(struct task_struct *task, gfp_t gfp_flags,
-				int node)
+int create_task_io_context(struct task_struct *task, gfp_t gfp_flags, int node)
 {
 	struct io_context *ioc;
 
 	ioc = kmem_cache_alloc_node(iocontext_cachep, gfp_flags | __GFP_ZERO,
 				    node);
 	if (unlikely(!ioc))
-		return;
+		return -ENOMEM;
 
 	/* initialize */
 	atomic_long_set(&ioc->refcount, 1);
-	atomic_set(&ioc->nr_tasks, 1);
+	atomic_set(&ioc->active_ref, 1);
 	spin_lock_init(&ioc->lock);
 	INIT_RADIX_TREE(&ioc->icq_tree, GFP_ATOMIC | __GFP_HIGH);
 	INIT_HLIST_HEAD(&ioc->icq_list);
@@ -250,6 +263,8 @@ void create_io_context_slowpath(struct task_struct *task, gfp_t gfp_flags,
 	else
 		kmem_cache_free(iocontext_cachep, ioc);
 	task_unlock(task);
+
+	return 0;
 }
 
 /**
@@ -281,7 +296,7 @@ struct io_context *get_task_io_context(struct task_struct *task,
 			return ioc;
 		}
 		task_unlock(task);
-	} while (create_io_context(task, gfp_flags, node));
+	} while (!create_task_io_context(task, gfp_flags, node));
 
 	return NULL;
 }
@@ -325,26 +340,23 @@ EXPORT_SYMBOL(ioc_lookup_icq);
 
 /**
  * ioc_create_icq - create and link io_cq
+ * @ioc: io_context of interest
  * @q: request_queue of interest
  * @gfp_mask: allocation mask
  *
- * Make sure io_cq linking %current->io_context and @q exists.  If either
- * io_context and/or icq don't exist, they will be created using @gfp_mask.
+ * Make sure io_cq linking @ioc and @q exists.  If icq doesn't exist, they
+ * will be created using @gfp_mask.
  *
  * The caller is responsible for ensuring @ioc won't go away and @q is
  * alive and will stay alive until this function returns.
  */
-struct io_cq *ioc_create_icq(struct request_queue *q, gfp_t gfp_mask)
+struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q,
+			     gfp_t gfp_mask)
 {
 	struct elevator_type *et = q->elevator->type;
-	struct io_context *ioc;
 	struct io_cq *icq;
 
 	/* allocate stuff */
-	ioc = create_io_context(current, gfp_mask, q->node);
-	if (!ioc)
-		return NULL;
-
 	icq = kmem_cache_alloc_node(et->icq_cache, gfp_mask | __GFP_ZERO,
 				    q->node);
 	if (!icq)
@@ -382,74 +394,6 @@ struct io_cq *ioc_create_icq(struct request_queue *q, gfp_t gfp_mask)
 	return icq;
 }
 
-void ioc_set_icq_flags(struct io_context *ioc, unsigned int flags)
-{
-	struct io_cq *icq;
-	struct hlist_node *n;
-
-	hlist_for_each_entry(icq, n, &ioc->icq_list, ioc_node)
-		icq->flags |= flags;
-}
-
-/**
- * ioc_ioprio_changed - notify ioprio change
- * @ioc: io_context of interest
- * @ioprio: new ioprio
- *
- * @ioc's ioprio has changed to @ioprio.  Set %ICQ_IOPRIO_CHANGED for all
- * icq's.  iosched is responsible for checking the bit and applying it on
- * request issue path.
- */
-void ioc_ioprio_changed(struct io_context *ioc, int ioprio)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&ioc->lock, flags);
-	ioc->ioprio = ioprio;
-	ioc_set_icq_flags(ioc, ICQ_IOPRIO_CHANGED);
-	spin_unlock_irqrestore(&ioc->lock, flags);
-}
-
-/**
- * ioc_cgroup_changed - notify cgroup change
- * @ioc: io_context of interest
- *
- * @ioc's cgroup has changed.  Set %ICQ_CGROUP_CHANGED for all icq's.
- * iosched is responsible for checking the bit and applying it on request
- * issue path.
- */
-void ioc_cgroup_changed(struct io_context *ioc)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&ioc->lock, flags);
-	ioc_set_icq_flags(ioc, ICQ_CGROUP_CHANGED);
-	spin_unlock_irqrestore(&ioc->lock, flags);
-}
-EXPORT_SYMBOL(ioc_cgroup_changed);
-
-/**
- * icq_get_changed - fetch and clear icq changed mask
- * @icq: icq of interest
- *
- * Fetch and clear ICQ_*_CHANGED bits from @icq.  Grabs and releases
- * @icq->ioc->lock.
- */
-unsigned icq_get_changed(struct io_cq *icq)
-{
-	unsigned int changed = 0;
-	unsigned long flags;
-
-	if (unlikely(icq->flags & ICQ_CHANGED_MASK)) {
-		spin_lock_irqsave(&icq->ioc->lock, flags);
-		changed = icq->flags & ICQ_CHANGED_MASK;
-		icq->flags &= ~ICQ_CHANGED_MASK;
-		spin_unlock_irqrestore(&icq->ioc->lock, flags);
-	}
-	return changed;
-}
-EXPORT_SYMBOL(icq_get_changed);
-
 static int __init blk_ioc_init(void)
 {
 	iocontext_cachep = kmem_cache_create("blkdev_ioc",