Revert "block: prepare I/O context code for BFQ-v6r1 for 3.1"

This reverts commit d51968e.

block/Kconfig.iosched

@@ -53,28 +53,6 @@ config CFQ_GROUP_IOSCHED
 	---help---
 	  Enable group IO scheduling in CFQ.
 
-config IOSCHED_BFQ
-	tristate "BFQ I/O scheduler"
-	depends on EXPERIMENTAL
-	default n
-	---help---
-	  The BFQ I/O scheduler tries to distribute bandwidth among
-	  all processes according to their weights.
-	  It aims at distributing the bandwidth as desired, independently of
-	  the disk parameters and with any workload. It also tries to
-	  guarantee low latency to interactive and soft real-time
-	  applications.  If compiled built-in (saying Y here), BFQ can
-	  be configured to support hierarchical scheduling.
-
-config CGROUP_BFQIO
-	bool "BFQ hierarchical scheduling support"
-	depends on CGROUPS && IOSCHED_BFQ=y
-	default n
-	---help---
-	  Enable hierarchical scheduling in BFQ, using the cgroups
-	  filesystem interface.  The name of the subsystem will be
-	  bfqio.
-
 choice
 	prompt "Default I/O scheduler"
 	default DEFAULT_CFQ
@@ -98,9 +76,6 @@ choice
 	config DEFAULT_CFQ
 		bool "CFQ" if IOSCHED_CFQ=y
 
-	config DEFAULT_BFQ
-		bool "BFQ" if IOSCHED_BFQ=y
-
 	config DEFAULT_NOOP
 		bool "No-op"
 
@@ -111,7 +86,6 @@ config DEFAULT_IOSCHED
 	default "deadline" if DEFAULT_DEADLINE
 	default "row" if DEFAULT_ROW
 	default "cfq" if DEFAULT_CFQ
-	default "bfq" if DEFAULT_BFQ
 	default "noop" if DEFAULT_NOOP
 
 endmenu

block/blk-ioc.c

@@ -5,7 +5,6 @@
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/bio.h>
-#include <linux/bitmap.h>
 #include <linux/blkdev.h>
 #include <linux/bootmem.h>	/* for max_pfn/max_low_pfn */
 #include <linux/slab.h>
@@ -17,12 +16,13 @@
  */
 static struct kmem_cache *iocontext_cachep;
 
-static void hlist_sched_dtor(struct io_context *ioc, struct hlist_head *list)
+static void cfq_dtor(struct io_context *ioc)
 {
-	if (!hlist_empty(list)) {
+	if (!hlist_empty(&ioc->cic_list)) {
 		struct cfq_io_context *cic;
 
-		cic = hlist_entry(list->first, struct cfq_io_context, cic_list);
+		cic = hlist_entry(ioc->cic_list.first, struct cfq_io_context,
+								cic_list);
 		cic->dtor(ioc);
 	}
 }
@@ -40,9 +40,7 @@ int put_io_context(struct io_context *ioc)
 
 	if (atomic_long_dec_and_test(&ioc->refcount)) {
 		rcu_read_lock();
-
-		hlist_sched_dtor(ioc, &ioc->cic_list);
-		hlist_sched_dtor(ioc, &ioc->bfq_cic_list);
+		cfq_dtor(ioc);
 		rcu_read_unlock();
 
 		kmem_cache_free(iocontext_cachep, ioc);
@@ -52,14 +50,15 @@ int put_io_context(struct io_context *ioc)
 }
 EXPORT_SYMBOL(put_io_context);
 
-static void hlist_sched_exit(struct io_context *ioc, struct hlist_head *list)
+static void cfq_exit(struct io_context *ioc)
 {
 	rcu_read_lock();
 
-	if (!hlist_empty(list)) {
+	if (!hlist_empty(&ioc->cic_list)) {
 		struct cfq_io_context *cic;
 
-		cic = hlist_entry(list->first, struct cfq_io_context, cic_list);
+		cic = hlist_entry(ioc->cic_list.first, struct cfq_io_context,
+								cic_list);
 		cic->exit(ioc);
 	}
 	rcu_read_unlock();
@@ -75,10 +74,9 @@ void exit_io_context(struct task_struct *task)
 	task->io_context = NULL;
 	task_unlock(task);
 
-	if (atomic_dec_and_test(&ioc->nr_tasks)) {
-		hlist_sched_exit(ioc, &ioc->cic_list);
-		hlist_sched_exit(ioc, &ioc->bfq_cic_list);
-	}
+	if (atomic_dec_and_test(&ioc->nr_tasks))
+		cfq_exit(ioc);
+
 	put_io_context(ioc);
 }
 
@@ -91,14 +89,12 @@ struct io_context *alloc_io_context(gfp_t gfp_flags, int node)
 		atomic_long_set(&ioc->refcount, 1);
 		atomic_set(&ioc->nr_tasks, 1);
 		spin_lock_init(&ioc->lock);
-		bitmap_zero(ioc->ioprio_changed, IOC_IOPRIO_CHANGED_BITS);
+		ioc->ioprio_changed = 0;
 		ioc->ioprio = 0;
 		ioc->last_waited = 0; /* doesn't matter... */
 		ioc->nr_batch_requests = 0; /* because this is 0 */
 		INIT_RADIX_TREE(&ioc->radix_root, GFP_ATOMIC | __GFP_HIGH);
 		INIT_HLIST_HEAD(&ioc->cic_list);
-		INIT_RADIX_TREE(&ioc->bfq_radix_root, GFP_ATOMIC | __GFP_HIGH);
-		INIT_HLIST_HEAD(&ioc->bfq_cic_list);
 		ioc->ioc_data = NULL;
 #if defined(CONFIG_BLK_CGROUP) || defined(CONFIG_BLK_CGROUP_MODULE)
 		ioc->cgroup_changed = 0;

block/cfq-iosched.c

@@ -2934,6 +2934,7 @@ static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
 static void cfq_ioc_set_ioprio(struct io_context *ioc)
 {
 	call_for_each_cic(ioc, changed_ioprio);
+	ioc->ioprio_changed = 0;
 }
 
 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
@@ -3225,13 +3226,8 @@ cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
 		goto err_free;
 
 out:
-	/*
-	 * test_and_clear_bit() implies a memory barrier, paired with
-	 * the wmb() in fs/ioprio.c, so the value seen for ioprio is the
-	 * new one.
-	 */
-	if (unlikely(test_and_clear_bit(IOC_CFQ_IOPRIO_CHANGED,
-					ioc->ioprio_changed)))
+	smp_read_barrier_depends();
+	if (unlikely(ioc->ioprio_changed))
 		cfq_ioc_set_ioprio(ioc);
 
 #ifdef CONFIG_CFQ_GROUP_IOSCHED

fs/ioprio.c

@@ -30,7 +30,7 @@
 
 int set_task_ioprio(struct task_struct *task, int ioprio)
 {
-	int err, i;
+	int err;
 	struct io_context *ioc;
 	const struct cred *cred = current_cred(), *tcred;
 
@@ -60,17 +60,12 @@ int set_task_ioprio(struct task_struct *task, int ioprio)
 			err = -ENOMEM;
 			break;
 		}
-		/* let other ioc users see the new values */
-		smp_wmb();
 		task->io_context = ioc;
 	} while (1);
 
 	if (!err) {
 		ioc->ioprio = ioprio;
-		/* make sure schedulers see the new ioprio value */
-		wmb();
-		for (i = 0; i < IOC_IOPRIO_CHANGED_BITS; i++)
-			set_bit(i, ioc->ioprio_changed);
+		ioc->ioprio_changed = 1;
 	}
 
 	task_unlock(task);

include/linux/iocontext.h

@@ -1,10 +1,10 @@
 #ifndef IOCONTEXT_H
 #define IOCONTEXT_H
 
-#include <linux/bitmap.h>
 #include <linux/radix-tree.h>
 #include <linux/rcupdate.h>
 
+struct cfq_queue;
 struct cfq_ttime {
 	unsigned long last_end_request;
 
@@ -16,15 +16,12 @@ struct cfq_ttime {
 struct cfq_io_context {
 	void *key;
 
-	void *cfqq[2];
+	struct cfq_queue *cfqq[2];
 
 	struct io_context *ioc;
 
 	struct cfq_ttime ttime;
 
-	unsigned int raising_time_left;
-	unsigned int saved_idle_window;
-
 	struct list_head queue_list;
 	struct hlist_node cic_list;
 
@@ -34,16 +31,6 @@ struct cfq_io_context {
 	struct rcu_head rcu_head;
 };
 
-/*
- * Indexes into the ioprio_changed bitmap.  A bit set indicates that
- * the corresponding I/O scheduler needs to see a ioprio update.
- */
-enum {
-	IOC_CFQ_IOPRIO_CHANGED,
-	IOC_BFQ_IOPRIO_CHANGED,
-	IOC_IOPRIO_CHANGED_BITS
-};
-
 /*
  * I/O subsystem state of the associated processes.  It is refcounted
  * and kmalloc'ed. These could be shared between processes.
@@ -56,7 +43,7 @@ struct io_context {
 	spinlock_t lock;
 
 	unsigned short ioprio;
-	DECLARE_BITMAP(ioprio_changed, IOC_IOPRIO_CHANGED_BITS);
+	unsigned short ioprio_changed;
 
 #if defined(CONFIG_BLK_CGROUP) || defined(CONFIG_BLK_CGROUP_MODULE)
 	unsigned short cgroup_changed;
@@ -70,8 +57,6 @@ struct io_context {
 
 	struct radix_tree_root radix_root;
 	struct hlist_head cic_list;
-	struct radix_tree_root bfq_radix_root;
-	struct hlist_head bfq_cic_list;
 	void __rcu *ioc_data;
 };