Merge branch 'for-linus' of git://git.kernel.dk/linux-2.6-block

* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
  cfq-iosched: fix RCU problem in cfq_cic_lookup()
  block: make blktrace use per-cpu buffers for message notes
  Added in elevator switch message to blktrace stream
  Added in MESSAGE notes for blktraces
  block: reorder cfq_queue to save space on 64bit builds
  block: Move the second call to get_request to the end of the loop
  splice: handle try_to_release_page() failure
  splice: fix sendfile() issue with relay

4 files changed, 72 insertions, 26 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 6a9cc0d22a6..1905aaba49f 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -806,35 +806,32 @@ static struct request *get_request_wait(struct request_queue *q, int rw_flags,
 	rq = get_request(q, rw_flags, bio, GFP_NOIO);
 	while (!rq) {
 		DEFINE_WAIT(wait);
+		struct io_context *ioc;
 		struct request_list *rl = &q->rq;
 
 		prepare_to_wait_exclusive(&rl->wait[rw], &wait,
 				TASK_UNINTERRUPTIBLE);
 
-		rq = get_request(q, rw_flags, bio, GFP_NOIO);
-
-		if (!rq) {
-			struct io_context *ioc;
+		blk_add_trace_generic(q, bio, rw, BLK_TA_SLEEPRQ);
 
-			blk_add_trace_generic(q, bio, rw, BLK_TA_SLEEPRQ);
-
-			__generic_unplug_device(q);
-			spin_unlock_irq(q->queue_lock);
-			io_schedule();
+		__generic_unplug_device(q);
+		spin_unlock_irq(q->queue_lock);
+		io_schedule();
 
-			/*
-			 * After sleeping, we become a "batching" process and
-			 * will be able to allocate at least one request, and
-			 * up to a big batch of them for a small period time.
-			 * See ioc_batching, ioc_set_batching
-			 */
-			ioc = current_io_context(GFP_NOIO, q->node);
-			ioc_set_batching(q, ioc);
+		/*
+		 * After sleeping, we become a "batching" process and
+		 * will be able to allocate at least one request, and
+		 * up to a big batch of them for a small period time.
+		 * See ioc_batching, ioc_set_batching
+		 */
+		ioc = current_io_context(GFP_NOIO, q->node);
+		ioc_set_batching(q, ioc);
 
-			spin_lock_irq(q->queue_lock);
-		}
+		spin_lock_irq(q->queue_lock);
 		finish_wait(&rl->wait[rw], &wait);
-	}
+
+		rq = get_request(q, rw_flags, bio, GFP_NOIO);
+	};
 
 	return rq;
 }
diff --git a/block/blktrace.c b/block/blktrace.c
index b2cbb4e5d76..7ae87cc4a16 100644
--- a/block/blktrace.c
+++ b/block/blktrace.c
@@ -75,6 +75,23 @@ static void trace_note_time(struct blk_trace *bt)
 	local_irq_restore(flags);
 }
 
+void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
+{
+	int n;
+	va_list args;
+	char *buf;
+
+	preempt_disable();
+	buf = per_cpu_ptr(bt->msg_data, smp_processor_id());
+	va_start(args, fmt);
+	n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
+	va_end(args);
+
+	trace_note(bt, 0, BLK_TN_MESSAGE, buf, n);
+	preempt_enable();
+}
+EXPORT_SYMBOL_GPL(__trace_note_message);
+
 static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
 			 pid_t pid)
 {
@@ -232,6 +249,7 @@ static void blk_trace_cleanup(struct blk_trace *bt)
 	debugfs_remove(bt->dropped_file);
 	blk_remove_tree(bt->dir);
 	free_percpu(bt->sequence);
+	free_percpu(bt->msg_data);
 	kfree(bt);
 }
 
@@ -346,6 +364,10 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 	if (!bt->sequence)
 		goto err;
 
+	bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG);
+	if (!bt->msg_data)
+		goto err;
+
 	ret = -ENOENT;
 	dir = blk_create_tree(buts->name);
 	if (!dir)
@@ -392,6 +414,7 @@ err:
 		if (bt->dropped_file)
 			debugfs_remove(bt->dropped_file);
 		free_percpu(bt->sequence);
+		free_percpu(bt->msg_data);
 		if (bt->rchan)
 			relay_close(bt->rchan);
 		kfree(bt);
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index b399c62936e..d01b411c72f 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -124,6 +124,8 @@ struct cfq_data {
 struct cfq_queue {
 	/* reference count */
 	atomic_t ref;
+	/* various state flags, see below */
+	unsigned int flags;
 	/* parent cfq_data */
 	struct cfq_data *cfqd;
 	/* service_tree member */
@@ -138,14 +140,14 @@ struct cfq_queue {
 	int queued[2];
 	/* currently allocated requests */
 	int allocated[2];
-	/* pending metadata requests */
-	int meta_pending;
 	/* fifo list of requests in sort_list */
 	struct list_head fifo;
 
 	unsigned long slice_end;
 	long slice_resid;
 
+	/* pending metadata requests */
+	int meta_pending;
 	/* number of requests that are on the dispatch list or inside driver */
 	int dispatched;
 
@@ -153,8 +155,6 @@ struct cfq_queue {
 	unsigned short ioprio, org_ioprio;
 	unsigned short ioprio_class, org_ioprio_class;
 
-	/* various state flags, see below */
-	unsigned int flags;
 };
 
 enum cfqq_state_flags {
@@ -1142,6 +1142,9 @@ static void cfq_put_queue(struct cfq_queue *cfqq)
 	kmem_cache_free(cfq_pool, cfqq);
 }
 
+/*
+ * Must always be called with the rcu_read_lock() held
+ */
 static void
 __call_for_each_cic(struct io_context *ioc,
 		    void (*func)(struct io_context *, struct cfq_io_context *))
@@ -1197,6 +1200,11 @@ static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
 	cfq_cic_free(cic);
 }
 
+/*
+ * Must be called with rcu_read_lock() held or preemption otherwise disabled.
+ * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
+ * and ->trim() which is called with the task lock held
+ */
 static void cfq_free_io_context(struct io_context *ioc)
 {
 	/*
@@ -1502,20 +1510,24 @@ static struct cfq_io_context *
 cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
 {
 	struct cfq_io_context *cic;
+	unsigned long flags;
 	void *k;
 
 	if (unlikely(!ioc))
 		return NULL;
 
+	rcu_read_lock();
+
 	/*
 	 * we maintain a last-hit cache, to avoid browsing over the tree
 	 */
 	cic = rcu_dereference(ioc->ioc_data);
-	if (cic && cic->key == cfqd)
+	if (cic && cic->key == cfqd) {
+		rcu_read_unlock();
 		return cic;
+	}
 
 	do {
-		rcu_read_lock();
 		cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd);
 		rcu_read_unlock();
 		if (!cic)
@@ -1524,10 +1536,13 @@ cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
 		k = cic->key;
 		if (unlikely(!k)) {
 			cfq_drop_dead_cic(cfqd, ioc, cic);
+			rcu_read_lock();
 			continue;
 		}
 
+		spin_lock_irqsave(&ioc->lock, flags);
 		rcu_assign_pointer(ioc->ioc_data, cic);
+		spin_unlock_irqrestore(&ioc->lock, flags);
 		break;
 	} while (1);
 
@@ -2134,6 +2149,10 @@ static void *cfq_init_queue(struct request_queue *q)
 
 static void cfq_slab_kill(void)
 {
+	/*
+	 * Caller already ensured that pending RCU callbacks are completed,
+	 * so we should have no busy allocations at this point.
+	 */
 	if (cfq_pool)
 		kmem_cache_destroy(cfq_pool);
 	if (cfq_ioc_pool)
@@ -2292,6 +2311,11 @@ static void __exit cfq_exit(void)
 	ioc_gone = &all_gone;
 	/* ioc_gone's update must be visible before reading ioc_count */
 	smp_wmb();
+
+	/*
+	 * this also protects us from entering cfq_slab_kill() with
+	 * pending RCU callbacks
+	 */
 	if (elv_ioc_count_read(ioc_count))
 		wait_for_completion(ioc_gone);
 	cfq_slab_kill();
diff --git a/block/elevator.c b/block/elevator.c
index 980f8ae147b..902dd1344d5 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -1110,6 +1110,8 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
 	queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q);
 	spin_unlock_irq(q->queue_lock);
 
+	blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name);
+
 	return 1;
 
 fail_register: