block: remove legacy IO schedulers

Retain the deadline documentation, as that carries over to mq-deadline
as well.

Tested-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

6 files changed, 0 insertions, 5734 deletions

diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched
index f95a48b0d7b2..4626b88b2d5a 100644
--- a/block/Kconfig.iosched
+++ b/block/Kconfig.iosched
@@ -3,67 +3,6 @@ if BLOCK
 
 menu "IO Schedulers"
 
-config IOSCHED_NOOP
-	bool
-	default y
-	---help---
-	  The no-op I/O scheduler is a minimal scheduler that does basic merging
-	  and sorting. Its main uses include non-disk based block devices like
-	  memory devices, and specialised software or hardware environments
-	  that do their own scheduling and require only minimal assistance from
-	  the kernel.
-
-config IOSCHED_DEADLINE
-	tristate "Deadline I/O scheduler"
-	default y
-	---help---
-	  The deadline I/O scheduler is simple and compact. It will provide
-	  CSCAN service with FIFO expiration of requests, switching to
-	  a new point in the service tree and doing a batch of IO from there
-	  in case of expiry.
-
-config IOSCHED_CFQ
-	tristate "CFQ I/O scheduler"
-	default y
-	---help---
-	  The CFQ I/O scheduler tries to distribute bandwidth equally
-	  among all processes in the system. It should provide a fair
-	  and low latency working environment, suitable for both desktop
-	  and server systems.
-
-	  This is the default I/O scheduler.
-
-config CFQ_GROUP_IOSCHED
-	bool "CFQ Group Scheduling support"
-	depends on IOSCHED_CFQ && BLK_CGROUP
-	---help---
-	  Enable group IO scheduling in CFQ.
-
-choice
-
-	prompt "Default I/O scheduler"
-	default DEFAULT_CFQ
-	help
-	  Select the I/O scheduler which will be used by default for all
-	  block devices.
-
-	config DEFAULT_DEADLINE
-		bool "Deadline" if IOSCHED_DEADLINE=y
-
-	config DEFAULT_CFQ
-		bool "CFQ" if IOSCHED_CFQ=y
-
-	config DEFAULT_NOOP
-		bool "No-op"
-
-endchoice
-
-config DEFAULT_IOSCHED
-	string
-	default "deadline" if DEFAULT_DEADLINE
-	default "cfq" if DEFAULT_CFQ
-	default "noop" if DEFAULT_NOOP
-
 config MQ_IOSCHED_DEADLINE
 	tristate "MQ deadline I/O scheduler"
 	default y
diff --git a/block/Makefile b/block/Makefile
index 213674c8faaa..eee1b4ceecf9 100644
--- a/block/Makefile
+++ b/block/Makefile
@@ -18,9 +18,6 @@ obj-$(CONFIG_BLK_DEV_BSGLIB)	+= bsg-lib.o
 obj-$(CONFIG_BLK_CGROUP)	+= blk-cgroup.o
 obj-$(CONFIG_BLK_DEV_THROTTLING)	+= blk-throttle.o
 obj-$(CONFIG_BLK_CGROUP_IOLATENCY)	+= blk-iolatency.o
-obj-$(CONFIG_IOSCHED_NOOP)	+= noop-iosched.o
-obj-$(CONFIG_IOSCHED_DEADLINE)	+= deadline-iosched.o
-obj-$(CONFIG_IOSCHED_CFQ)	+= cfq-iosched.o
 obj-$(CONFIG_MQ_IOSCHED_DEADLINE)	+= mq-deadline.o
 obj-$(CONFIG_MQ_IOSCHED_KYBER)	+= kyber-iosched.o
 bfq-y				:= bfq-iosched.o bfq-wf2q.o bfq-cgroup.o
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
deleted file mode 100644
index ed41aa978c4a..000000000000
--- a/block/cfq-iosched.c
+++ /dev/null
@@ -1,4916 +0,0 @@
-/*
- *  CFQ, or complete fairness queueing, disk scheduler.
- *
- *  Based on ideas from a previously unfinished io
- *  scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
- *
- *  Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
- */
-#include <linux/module.h>
-#include <linux/slab.h>
-#include <linux/sched/clock.h>
-#include <linux/blkdev.h>
-#include <linux/elevator.h>
-#include <linux/ktime.h>
-#include <linux/rbtree.h>
-#include <linux/ioprio.h>
-#include <linux/blktrace_api.h>
-#include <linux/blk-cgroup.h>
-#include "blk.h"
-#include "blk-wbt.h"
-
-/*
- * tunables
- */
-/* max queue in one round of service */
-static const int cfq_quantum = 8;
-static const u64 cfq_fifo_expire[2] = { NSEC_PER_SEC / 4, NSEC_PER_SEC / 8 };
-/* maximum backwards seek, in KiB */
-static const int cfq_back_max = 16 * 1024;
-/* penalty of a backwards seek */
-static const int cfq_back_penalty = 2;
-static const u64 cfq_slice_sync = NSEC_PER_SEC / 10;
-static u64 cfq_slice_async = NSEC_PER_SEC / 25;
-static const int cfq_slice_async_rq = 2;
-static u64 cfq_slice_idle = NSEC_PER_SEC / 125;
-static u64 cfq_group_idle = NSEC_PER_SEC / 125;
-static const u64 cfq_target_latency = (u64)NSEC_PER_SEC * 3/10; /* 300 ms */
-static const int cfq_hist_divisor = 4;
-
-/*
- * offset from end of queue service tree for idle class
- */
-#define CFQ_IDLE_DELAY		(NSEC_PER_SEC / 5)
-/* offset from end of group service tree under time slice mode */
-#define CFQ_SLICE_MODE_GROUP_DELAY (NSEC_PER_SEC / 5)
-/* offset from end of group service under IOPS mode */
-#define CFQ_IOPS_MODE_GROUP_DELAY (HZ / 5)
-
-/*
- * below this threshold, we consider thinktime immediate
- */
-#define CFQ_MIN_TT		(2 * NSEC_PER_SEC / HZ)
-
-#define CFQ_SLICE_SCALE		(5)
-#define CFQ_HW_QUEUE_MIN	(5)
-#define CFQ_SERVICE_SHIFT       12
-
-#define CFQQ_SEEK_THR		(sector_t)(8 * 100)
-#define CFQQ_CLOSE_THR		(sector_t)(8 * 1024)
-#define CFQQ_SECT_THR_NONROT	(sector_t)(2 * 32)
-#define CFQQ_SEEKY(cfqq)	(hweight32(cfqq->seek_history) > 32/8)
-
-#define RQ_CIC(rq)		icq_to_cic((rq)->elv.icq)
-#define RQ_CFQQ(rq)		(struct cfq_queue *) ((rq)->elv.priv[0])
-#define RQ_CFQG(rq)		(struct cfq_group *) ((rq)->elv.priv[1])
-
-static struct kmem_cache *cfq_pool;
-
-#define CFQ_PRIO_LISTS		IOPRIO_BE_NR
-#define cfq_class_idle(cfqq)	((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
-#define cfq_class_rt(cfqq)	((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
-
-#define sample_valid(samples)	((samples) > 80)
-#define rb_entry_cfqg(node)	rb_entry((node), struct cfq_group, rb_node)
-
-/* blkio-related constants */
-#define CFQ_WEIGHT_LEGACY_MIN	10
-#define CFQ_WEIGHT_LEGACY_DFL	500
-#define CFQ_WEIGHT_LEGACY_MAX	1000
-
-struct cfq_ttime {
-	u64 last_end_request;
-
-	u64 ttime_total;
-	u64 ttime_mean;
-	unsigned long ttime_samples;
-};
-
-/*
- * Most of our rbtree usage is for sorting with min extraction, so
- * if we cache the leftmost node we don't have to walk down the tree
- * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
- * move this into the elevator for the rq sorting as well.
- */
-struct cfq_rb_root {
-	struct rb_root_cached rb;
-	struct rb_node *rb_rightmost;
-	unsigned count;
-	u64 min_vdisktime;
-	struct cfq_ttime ttime;
-};
-#define CFQ_RB_ROOT	(struct cfq_rb_root) { .rb = RB_ROOT_CACHED, \
-			.rb_rightmost = NULL,			     \
-			.ttime = {.last_end_request = ktime_get_ns(),},}
-
-/*
- * Per process-grouping structure
- */
-struct cfq_queue {
-	/* reference count */
-	int ref;
-	/* various state flags, see below */
-	unsigned int flags;
-	/* parent cfq_data */
-	struct cfq_data *cfqd;
-	/* service_tree member */
-	struct rb_node rb_node;
-	/* service_tree key */
-	u64 rb_key;
-	/* prio tree member */
-	struct rb_node p_node;
-	/* prio tree root we belong to, if any */
-	struct rb_root *p_root;
-	/* sorted list of pending requests */
-	struct rb_root sort_list;
-	/* if fifo isn't expired, next request to serve */
-	struct request *next_rq;
-	/* requests queued in sort_list */
-	int queued[2];
-	/* currently allocated requests */
-	int allocated[2];
-	/* fifo list of requests in sort_list */
-	struct list_head fifo;
-
-	/* time when queue got scheduled in to dispatch first request. */
-	u64 dispatch_start;
-	u64 allocated_slice;
-	u64 slice_dispatch;
-	/* time when first request from queue completed and slice started. */
-	u64 slice_start;
-	u64 slice_end;
-	s64 slice_resid;
-
-	/* pending priority requests */
-	int prio_pending;
-	/* number of requests that are on the dispatch list or inside driver */
-	int dispatched;
-
-	/* io prio of this group */
-	unsigned short ioprio, org_ioprio;
-	unsigned short ioprio_class, org_ioprio_class;
-
-	pid_t pid;
-
-	u32 seek_history;
-	sector_t last_request_pos;
-
-	struct cfq_rb_root *service_tree;
-	struct cfq_queue *new_cfqq;
-	struct cfq_group *cfqg;
-	/* Number of sectors dispatched from queue in single dispatch round */
-	unsigned long nr_sectors;
-};
-
-/*
- * First index in the service_trees.
- * IDLE is handled separately, so it has negative index
- */
-enum wl_class_t {
-	BE_WORKLOAD = 0,
-	RT_WORKLOAD = 1,
-	IDLE_WORKLOAD = 2,
-	CFQ_PRIO_NR,
-};
-
-/*
- * Second index in the service_trees.
- */
-enum wl_type_t {
-	ASYNC_WORKLOAD = 0,
-	SYNC_NOIDLE_WORKLOAD = 1,
-	SYNC_WORKLOAD = 2
-};
-
-struct cfqg_stats {
-#ifdef CONFIG_CFQ_GROUP_IOSCHED
-	/* number of ios merged */
-	struct blkg_rwstat		merged;
-	/* total time spent on device in ns, may not be accurate w/ queueing */
-	struct blkg_rwstat		service_time;
-	/* total time spent waiting in scheduler queue in ns */
-	struct blkg_rwstat		wait_time;
-	/* number of IOs queued up */
-	struct blkg_rwstat		queued;
-	/* total disk time and nr sectors dispatched by this group */
-	struct blkg_stat		time;
-#ifdef CONFIG_DEBUG_BLK_CGROUP
-	/* time not charged to this cgroup */
-	struct blkg_stat		unaccounted_time;
-	/* sum of number of ios queued across all samples */
-	struct blkg_stat		avg_queue_size_sum;
-	/* count of samples taken for average */
-	struct blkg_stat		avg_queue_size_samples;
-	/* how many times this group has been removed from service tree */
-	struct blkg_stat		dequeue;
-	/* total time spent waiting for it to be assigned a timeslice. */
-	struct blkg_stat		group_wait_time;
-	/* time spent idling for this blkcg_gq */
-	struct blkg_stat		idle_time;
-	/* total time with empty current active q with other requests queued */
-	struct blkg_stat		empty_time;
-	/* fields after this shouldn't be cleared on stat reset */
-	u64				start_group_wait_time;
-	u64				start_idle_time;
-	u64				start_empty_time;
-	uint16_t			flags;
-#endif	/* CONFIG_DEBUG_BLK_CGROUP */
-#endif	/* CONFIG_CFQ_GROUP_IOSCHED */
-};
-
-/* Per-cgroup data */
-struct cfq_group_data {
-	/* must be the first member */
-	struct blkcg_policy_data cpd;
-
-	unsigned int weight;
-	unsigned int leaf_weight;
-};
-
-/* This is per cgroup per device grouping structure */
-struct cfq_group {
-	/* must be the first member */
-	struct blkg_policy_data pd;
-
-	/* group service_tree member */
-	struct rb_node rb_node;
-
-	/* group service_tree key */
-	u64 vdisktime;
-
-	/*
-	 * The number of active cfqgs and sum of their weights under this
-	 * cfqg.  This covers this cfqg's leaf_weight and all children's
-	 * weights, but does not cover weights of further descendants.
-	 *
-	 * If a cfqg is on the service tree, it's active.  An active cfqg
-	 * also activates its parent and contributes to the children_weight
-	 * of the parent.
-	 */
-	int nr_active;
-	unsigned int children_weight;
-
-	/*
-	 * vfraction is the fraction of vdisktime that the tasks in this
-	 * cfqg are entitled to.  This is determined by compounding the
-	 * ratios walking up from this cfqg to the root.
-	 *
-	 * It is in fixed point w/ CFQ_SERVICE_SHIFT and the sum of all
-	 * vfractions on a service tree is approximately 1.  The sum may
-	 * deviate a bit due to rounding errors and fluctuations caused by
-	 * cfqgs entering and leaving the service tree.
-	 */
-	unsigned int vfraction;
-
-	/*
-	 * There are two weights - (internal) weight is the weight of this
-	 * cfqg against the sibling cfqgs.  leaf_weight is the wight of
-	 * this cfqg against the child cfqgs.  For the root cfqg, both
-	 * weights are kept in sync for backward compatibility.
-	 */
-	unsigned int weight;
-	unsigned int new_weight;
-	unsigned int dev_weight;
-
-	unsigned int leaf_weight;
-	unsigned int new_leaf_weight;
-	unsigned int dev_leaf_weight;
-
-	/* number of cfqq currently on this group */
-	int nr_cfqq;
-
-	/*
-	 * Per group busy queues average. Useful for workload slice calc. We
-	 * create the array for each prio class but at run time it is used
-	 * only for RT and BE class and slot for IDLE class remains unused.
-	 * This is primarily done to avoid confusion and a gcc warning.
-	 */
-	unsigned int busy_queues_avg[CFQ_PRIO_NR];
-	/*
-	 * rr lists of queues with requests. We maintain service trees for
-	 * RT and BE classes. These trees are subdivided in subclasses
-	 * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
-	 * class there is no subclassification and all the cfq queues go on
-	 * a single tree service_tree_idle.
-	 * Counts are embedded in the cfq_rb_root
-	 */
-	struct cfq_rb_root service_trees[2][3];
-	struct cfq_rb_root service_tree_idle;
-
-	u64 saved_wl_slice;
-	enum wl_type_t saved_wl_type;
-	enum wl_class_t saved_wl_class;
-
-	/* number of requests that are on the dispatch list or inside driver */
-	int dispatched;
-	struct cfq_ttime ttime;
-	struct cfqg_stats stats;	/* stats for this cfqg */
-
-	/* async queue for each priority case */
-	struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
-	struct cfq_queue *async_idle_cfqq;
-
-};
-
-struct cfq_io_cq {
-	struct io_cq		icq;		/* must be the first member */
-	struct cfq_queue	*cfqq[2];
-	struct cfq_ttime	ttime;
-	int			ioprio;		/* the current ioprio */
-#ifdef CONFIG_CFQ_GROUP_IOSCHED
-	uint64_t		blkcg_serial_nr; /* the current blkcg serial */
-#endif
-};
-
-/*
- * Per block device queue structure
- */
-struct cfq_data {
-	struct request_queue *queue;
-	/* Root service tree for cfq_groups */
-	struct cfq_rb_root grp_service_tree;
-	struct cfq_group *root_group;
-
-	/*
-	 * The priority currently being served
-	 */
-	enum wl_class_t serving_wl_class;
-	enum wl_type_t serving_wl_type;
-	u64 workload_expires;
-	struct cfq_group *serving_group;
-
-	/*
-	 * Each priority tree is sorted by next_request position.  These
-	 * trees are used when determining if two or more queues are
-	 * interleaving requests (see cfq_close_cooperator).
-	 */
-	struct rb_root prio_trees[CFQ_PRIO_LISTS];
-
-	unsigned int busy_queues;
-	unsigned int busy_sync_queues;
-
-	int rq_in_driver;
-	int rq_in_flight[2];
-
-	/*
-	 * queue-depth detection
-	 */
-	int rq_queued;
-	int hw_tag;
-	/*
-	 * hw_tag can be
-	 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
-	 *  1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
-	 *  0 => no NCQ
-	 */
-	int hw_tag_est_depth;
-	unsigned int hw_tag_samples;
-
-	/*
-	 * idle window management
-	 */
-	struct hrtimer idle_slice_timer;
-	struct work_struct unplug_work;
-
-	struct cfq_queue *active_queue;
-	struct cfq_io_cq *active_cic;
-
-	sector_t last_position;
-
-	/*
-	 * tunables, see top of file
-	 */
-	unsigned int cfq_quantum;
-	unsigned int cfq_back_penalty;
-	unsigned int cfq_back_max;
-	unsigned int cfq_slice_async_rq;
-	unsigned int cfq_latency;
-	u64 cfq_fifo_expire[2];
-	u64 cfq_slice[2];
-	u64 cfq_slice_idle;
-	u64 cfq_group_idle;
-	u64 cfq_target_latency;
-
-	/*
-	 * Fallback dummy cfqq for extreme OOM conditions
-	 */
-	struct cfq_queue oom_cfqq;
-
-	u64 last_delayed_sync;
-};
-
-static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
-static void cfq_put_queue(struct cfq_queue *cfqq);
-
-static struct cfq_rb_root *st_for(struct cfq_group *cfqg,
-					    enum wl_class_t class,
-					    enum wl_type_t type)
-{
-	if (!cfqg)
-		return NULL;
-
-	if (class == IDLE_WORKLOAD)
-		return &cfqg->service_tree_idle;
-
-	return &cfqg->service_trees[class][type];
-}
-
-enum cfqq_state_flags {
-	CFQ_CFQQ_FLAG_on_rr = 0,	/* on round-robin busy list */
-	CFQ_CFQQ_FLAG_wait_request,	/* waiting for a request */
-	CFQ_CFQQ_FLAG_must_dispatch,	/* must be allowed a dispatch */
-	CFQ_CFQQ_FLAG_must_alloc_slice,	/* per-slice must_alloc flag */
-	CFQ_CFQQ_FLAG_fifo_expire,	/* FIFO checked in this slice */
-	CFQ_CFQQ_FLAG_idle_window,	/* slice idling enabled */
-	CFQ_CFQQ_FLAG_prio_changed,	/* task priority has changed */
-	CFQ_CFQQ_FLAG_slice_new,	/* no requests dispatched in slice */
-	CFQ_CFQQ_FLAG_sync,		/* synchronous queue */
-	CFQ_CFQQ_FLAG_coop,		/* cfqq is shared */
-	CFQ_CFQQ_FLAG_split_coop,	/* shared cfqq will be splitted */
-	CFQ_CFQQ_FLAG_deep,		/* sync cfqq experienced large depth */
-	CFQ_CFQQ_FLAG_wait_busy,	/* Waiting for next request */
-};
-
-#define CFQ_CFQQ_FNS(name)						\
-static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq)		\
-{									\
-	(cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name);			\
-}									\
-static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq)	\
-{									\
-	(cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name);			\
-}									\
-static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq)		\
-{									\
-	return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0;	\
-}
-
-CFQ_CFQQ_FNS(on_rr);
-CFQ_CFQQ_FNS(wait_request);
-CFQ_CFQQ_FNS(must_dispatch);
-CFQ_CFQQ_FNS(must_alloc_slice);
-CFQ_CFQQ_FNS(fifo_expire);
-CFQ_CFQQ_FNS(idle_window);
-CFQ_CFQQ_FNS(prio_changed);
-CFQ_CFQQ_FNS(slice_new);
-CFQ_CFQQ_FNS(sync);
-CFQ_CFQQ_FNS(coop);
-CFQ_CFQQ_FNS(split_coop);
-CFQ_CFQQ_FNS(deep);
-CFQ_CFQQ_FNS(wait_busy);
-#undef CFQ_CFQQ_FNS
-
-#if defined(CONFIG_CFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
-
-/* cfqg stats flags */
-enum cfqg_stats_flags {
-	CFQG_stats_waiting = 0,
-	CFQG_stats_idling,
-	CFQG_stats_empty,
-};
-
-#define CFQG_FLAG_FNS(name)						\
-static inline void cfqg_stats_mark_##name(struct cfqg_stats *stats)	\
-{									\
-	stats->flags |= (1 << CFQG_stats_##name);			\
-}									\
-static inline void cfqg_stats_clear_##name(struct cfqg_stats *stats)	\
-{									\
-	stats->flags &= ~(1 << CFQG_stats_##name);			\
-}									\
-static inline int cfqg_stats_##name(struct cfqg_stats *stats)		\
-{									\
-	return (stats->flags & (1 << CFQG_stats_##name)) != 0;		\
-}									\
-
-CFQG_FLAG_FNS(waiting)
-CFQG_FLAG_FNS(idling)
-CFQG_FLAG_FNS(empty)
-#undef CFQG_FLAG_FNS
-
-/* This should be called with the queue_lock held. */
-static void cfqg_stats_update_group_wait_time(struct cfqg_stats *stats)
-{
-	u64 now;
-
-	if (!cfqg_stats_waiting(stats))
-		return;
-
-	now = ktime_get_ns();
-	if (now > stats->start_group_wait_time)
-		blkg_stat_add(&stats->group_wait_time,
-			      now - stats->start_group_wait_time);
-	cfqg_stats_clear_waiting(stats);
-}
-
-/* This should be called with the queue_lock held. */
-static void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg,
-						 struct cfq_group *curr_cfqg)
-{
-	struct cfqg_stats *stats = &cfqg->stats;
-
-	if (cfqg_stats_waiting(stats))
-		return;
-	if (cfqg == curr_cfqg)
-		return;
-	stats->start_group_wait_time = ktime_get_ns();
-	cfqg_stats_mark_waiting(stats);
-}
-
-/* This should be called with the queue_lock held. */
-static void cfqg_stats_end_empty_time(struct cfqg_stats *stats)
-{
-	u64 now;
-
-	if (!cfqg_stats_empty(stats))
-		return;
-
-	now = ktime_get_ns();
-	if (now > stats->start_empty_time)
-		blkg_stat_add(&stats->empty_time,
-			      now - stats->start_empty_time);
-	cfqg_stats_clear_empty(stats);
-}
-
-static void cfqg_stats_update_dequeue(struct cfq_group *cfqg)
-{
-	blkg_stat_add(&cfqg->stats.dequeue, 1);
-}
-
-static void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg)
-{
-	struct cfqg_stats *stats = &cfqg->stats;
-
-	if (blkg_rwstat_total(&stats->queued))
-		return;
-
-	/*
-	 * group is already marked empty. This can happen if cfqq got new
-	 * request in parent group and moved to this group while being added
-	 * to service tree. Just ignore the event and move on.
-	 */
-	if (cfqg_stats_empty(stats))
-		return;
-
-	stats->start_empty_time = ktime_get_ns();
-	cfqg_stats_mark_empty(stats);
-}
-
-static void cfqg_stats_update_idle_time(struct cfq_group *cfqg)
-{
-	struct cfqg_stats *stats = &cfqg->stats;
-
-	if (cfqg_stats_idling(stats)) {
-		u64 now = ktime_get_ns();
-
-		if (now > stats->start_idle_time)
-			blkg_stat_add(&stats->idle_time,
-				      now - stats->start_idle_time);
-		cfqg_stats_clear_idling(stats);
-	}
-}
-
-static void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg)
-{
-	struct cfqg_stats *stats = &cfqg->stats;
-
-	BUG_ON(cfqg_stats_idling(stats));
-
-	stats->start_idle_time = ktime_get_ns();
-	cfqg_stats_mark_idling(stats);
-}
-
-static void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg)
-{
-	struct cfqg_stats *stats = &cfqg->stats;
-
-	blkg_stat_add(&stats->avg_queue_size_sum,
-		      blkg_rwstat_total(&stats->queued));
-	blkg_stat_add(&stats->avg_queue_size_samples, 1);
-	cfqg_stats_update_group_wait_time(stats);
-}
-
-#else	/* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
-
-static inline void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg, struct cfq_group *curr_cfqg) { }
-static inline void cfqg_stats_end_empty_time(struct cfqg_stats *stats) { }
-static inline void cfqg_stats_update_dequeue(struct cfq_group *cfqg) { }
-static inline void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg) { }
-static inline void cfqg_stats_update_idle_time(struct cfq_group *cfqg) { }
-static inline void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg) { }
-static inline void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) { }
-
-#endif	/* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
-
-#ifdef CONFIG_CFQ_GROUP_IOSCHED
-
-static inline struct cfq_group *pd_to_cfqg(struct blkg_policy_data *pd)
-{
-	return pd ? container_of(pd, struct cfq_group, pd) : NULL;
-}
-
-static struct cfq_group_data
-*cpd_to_cfqgd(struct blkcg_policy_data *cpd)
-{
-	return cpd ? container_of(cpd, struct cfq_group_data, cpd) : NULL;
-}
-
-static inline struct blkcg_gq *cfqg_to_blkg(struct cfq_group *cfqg)
-{
-	return pd_to_blkg(&cfqg->pd);
-}
-
-static struct blkcg_policy blkcg_policy_cfq;
-
-static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg)
-{
-	return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq));
-}
-
-static struct cfq_group_data *blkcg_to_cfqgd(struct blkcg *blkcg)
-{
-	return cpd_to_cfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_cfq));
-}
-
-static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg)
-{
-	struct blkcg_gq *pblkg = cfqg_to_blkg(cfqg)->parent;
-
-	return pblkg ? blkg_to_cfqg(pblkg) : NULL;
-}
-
-static inline bool cfqg_is_descendant(struct cfq_group *cfqg,
-				      struct cfq_group *ancestor)
-{
-	return cgroup_is_descendant(cfqg_to_blkg(cfqg)->blkcg->css.cgroup,
-				    cfqg_to_blkg(ancestor)->blkcg->css.cgroup);
-}
-
-static inline void cfqg_get(struct cfq_group *cfqg)
-{
-	return blkg_get(cfqg_to_blkg(cfqg));
-}
-
-static inline void cfqg_put(struct cfq_group *cfqg)
-{
-	return blkg_put(cfqg_to_blkg(cfqg));
-}
-
-#define cfq_log_cfqq(cfqd, cfqq, fmt, args...)	do {			\
-	blk_add_cgroup_trace_msg((cfqd)->queue,				\
-			cfqg_to_blkg((cfqq)->cfqg)->blkcg,		\
-			"cfq%d%c%c " fmt, (cfqq)->pid,			\
-			cfq_cfqq_sync((cfqq)) ? 'S' : 'A',		\
-			cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
-			  ##args);					\
-} while (0)
-
-#define cfq_log_cfqg(cfqd, cfqg, fmt, args...)	do {			\
-	blk_add_cgroup_trace_msg((cfqd)->queue,				\
-			cfqg_to_blkg(cfqg)->blkcg, fmt, ##args);	\
-} while (0)
-
-static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
-					    struct cfq_group *curr_cfqg,
-					    unsigned int op)
-{
-	blkg_rwstat_add(&cfqg->stats.queued, op, 1);
-	cfqg_stats_end_empty_time(&cfqg->stats);
-	cfqg_stats_set_start_group_wait_time(cfqg, curr_cfqg);
-}
-
-static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
-			uint64_t time, unsigned long unaccounted_time)
-{
-	blkg_stat_add(&cfqg->stats.time, time);
-#ifdef CONFIG_DEBUG_BLK_CGROUP
-	blkg_stat_add(&cfqg->stats.unaccounted_time, unaccounted_time);
-#endif
-}
-
-static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg,
-					       unsigned int op)
-{
-	blkg_rwstat_add(&cfqg->stats.queued, op, -1);
-}
-
-static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg,
-					       unsigned int op)
-{
-	blkg_rwstat_add(&cfqg->stats.merged, op, 1);
-}
-
-static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
-						u64 start_time_ns,
-						u64 io_start_time_ns,
-						unsigned int op)
-{
-	struct cfqg_stats *stats = &cfqg->stats;
-	u64 now = ktime_get_ns();
-
-	if (now > io_start_time_ns)
-		blkg_rwstat_add(&stats->service_time, op,
-				now - io_start_time_ns);
-	if (io_start_time_ns > start_time_ns)
-		blkg_rwstat_add(&stats->wait_time, op,
-				io_start_time_ns - start_time_ns);
-}
-
-/* @stats = 0 */
-static void cfqg_stats_reset(struct cfqg_stats *stats)
-{
-	/* queued stats shouldn't be cleared */
-	blkg_rwstat_reset(&stats->merged);
-	blkg_rwstat_reset(&stats->service_time);
-	blkg_rwstat_reset(&stats->wait_time);
-	blkg_stat_reset(&stats->time);
-#ifdef CONFIG_DEBUG_BLK_CGROUP
-	blkg_stat_reset(&stats->unaccounted_time);
-	blkg_stat_reset(&stats->avg_queue_size_sum);
-	blkg_stat_reset(&stats->avg_queue_size_samples);
-	blkg_stat_reset(&stats->dequeue);
-	blkg_stat_reset(&stats->group_wait_time);
-	blkg_stat_reset(&stats->idle_time);
-	blkg_stat_reset(&stats->empty_time);
-#endif
-}
-
-/* @to += @from */
-static void cfqg_stats_add_aux(struct cfqg_stats *to, struct cfqg_stats *from)
-{
-	/* queued stats shouldn't be cleared */
-	blkg_rwstat_add_aux(&to->merged, &from->merged);
-	blkg_rwstat_add_aux(&to->service_time, &from->service_time);
-	blkg_rwstat_add_aux(&to->wait_time, &from->wait_time);
-	blkg_stat_add_aux(&from->time, &from->time);
-#ifdef CONFIG_DEBUG_BLK_CGROUP
-	blkg_stat_add_aux(&to->unaccounted_time, &from->unaccounted_time);
-	blkg_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
-	blkg_stat_add_aux(&to->avg_queue_size_samples, &from->avg_queue_size_samples);
-	blkg_stat_add_aux(&to->dequeue, &from->dequeue);
-	blkg_stat_add_aux(&to->group_wait_time, &from->group_wait_time);
-	blkg_stat_add_aux(&to->idle_time, &from->idle_time);
-	blkg_stat_add_aux(&to->empty_time, &from->empty_time);
-#endif
-}
-
-/*
- * Transfer @cfqg's stats to its parent's aux counts so that the ancestors'
- * recursive stats can still account for the amount used by this cfqg after
- * it's gone.
- */
-static void cfqg_stats_xfer_dead(struct cfq_group *cfqg)
-{
-	struct cfq_group *parent = cfqg_parent(cfqg);
-
-	lockdep_assert_held(cfqg_to_blkg(cfqg)->q->queue_lock);
-
-	if (unlikely(!parent))
-		return;
-
-	cfqg_stats_add_aux(&parent->stats, &cfqg->stats);
-	cfqg_stats_reset(&cfqg->stats);
-}
-
-#else	/* CONFIG_CFQ_GROUP_IOSCHED */
-
-static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg) { return NULL; }
-static inline bool cfqg_is_descendant(struct cfq_group *cfqg,
-				      struct cfq_group *ancestor)
-{
-	return true;
-}
-static inline void cfqg_get(struct cfq_group *cfqg) { }
-static inline void cfqg_put(struct cfq_group *cfqg) { }
-
-#define cfq_log_cfqq(cfqd, cfqq, fmt, args...)	\
-	blk_add_trace_msg((cfqd)->queue, "cfq%d%c%c " fmt, (cfqq)->pid,	\
-			cfq_cfqq_sync((cfqq)) ? 'S' : 'A',		\
-			cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
-				##args)
-#define cfq_log_cfqg(cfqd, cfqg, fmt, args...)		do {} while (0)
-
-static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
-			struct cfq_group *curr_cfqg, unsigned int op) { }
-static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
-			uint64_t time, unsigned long unaccounted_time) { }
-static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg,
-			unsigned int op) { }
-static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg,
-			unsigned int op) { }
-static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
-						u64 start_time_ns,
-						u64 io_start_time_ns,
-						unsigned int op) { }
-
-#endif	/* CONFIG_CFQ_GROUP_IOSCHED */
-
-#define cfq_log(cfqd, fmt, args...)	\
-	blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
-
-/* Traverses through cfq group service trees */
-#define for_each_cfqg_st(cfqg, i, j, st) \
-	for (i = 0; i <= IDLE_WORKLOAD; i++) \
-		for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
-			: &cfqg->service_tree_idle; \
-			(i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
-			(i == IDLE_WORKLOAD && j == 0); \
-			j++, st = i < IDLE_WORKLOAD ? \
-			&cfqg->service_trees[i][j]: NULL) \
-
-static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
-	struct cfq_ttime *ttime, bool group_idle)
-{
-	u64 slice;
-	if (!sample_valid(ttime->ttime_samples))
-		return false;
-	if (group_idle)
-		slice = cfqd->cfq_group_idle;
-	else
-		slice = cfqd->cfq_slice_idle;
-	return ttime->ttime_mean > slice;
-}
-
-static inline bool iops_mode(struct cfq_data *cfqd)
-{
-	/*
-	 * If we are not idling on queues and it is a NCQ drive, parallel
-	 * execution of requests is on and measuring time is not possible
-	 * in most of the cases until and unless we drive shallower queue
-	 * depths and that becomes a performance bottleneck. In such cases
-	 * switch to start providing fairness in terms of number of IOs.
-	 */
-	if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
-		return true;
-	else
-		return false;
-}
-
-static inline enum wl_class_t cfqq_class(struct cfq_queue *cfqq)
-{
-	if (cfq_class_idle(cfqq))
-		return IDLE_WORKLOAD;
-	if (cfq_class_rt(cfqq))
-		return RT_WORKLOAD;
-	return BE_WORKLOAD;
-}
-
-
-static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
-{
-	if (!cfq_cfqq_sync(cfqq))
-		return ASYNC_WORKLOAD;
-	if (!cfq_cfqq_idle_window(cfqq))
-		return SYNC_NOIDLE_WORKLOAD;
-	return SYNC_WORKLOAD;
-}
-
-static inline int cfq_group_busy_queues_wl(enum wl_class_t wl_class,
-					struct cfq_data *cfqd,
-					struct cfq_group *cfqg)
-{
-	if (wl_class == IDLE_WORKLOAD)
-		return cfqg->service_tree_idle.count;
-
-	return cfqg->service_trees[wl_class][ASYNC_WORKLOAD].count +
-		cfqg->service_trees[wl_class][SYNC_NOIDLE_WORKLOAD].count +
-		cfqg->service_trees[wl_class][SYNC_WORKLOAD].count;
-}
-
-static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
-					struct cfq_group *cfqg)
-{
-	return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count +
-		cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
-}
-
-static void cfq_dispatch_insert(struct request_queue *, struct request *);
-static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, bool is_sync,
-				       struct cfq_io_cq *cic, struct bio *bio);
-
-static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq)
-{
-	/* cic->icq is the first member, %NULL will convert to %NULL */
-	return container_of(icq, struct cfq_io_cq, icq);
-}
-
-static inline struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *cfqd,
-					       struct io_context *ioc)
-{
-	if (ioc)
-		return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue));
-	return NULL;
-}
-
-static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync)
-{
-	return cic->cfqq[is_sync];
-}
-
-static inline void cic_set_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq,
-				bool is_sync)
-{
-	cic->cfqq[is_sync] = cfqq;
-}
-
-static inline struct cfq_data *cic_to_cfqd(struct cfq_io_cq *cic)
-{
-	return cic->icq.q->elevator->elevator_data;
-}
-
-/*
- * scheduler run of queue, if there are requests pending and no one in the
- * driver that will restart queueing
- */
-static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
-{
-	if (cfqd->busy_queues) {
-		cfq_log(cfqd, "schedule dispatch");
-		kblockd_schedule_work(&cfqd->unplug_work);
-	}
-}
-
-/*
- * Scale schedule slice based on io priority. Use the sync time slice only
- * if a queue is marked sync and has sync io queued. A sync queue with async
- * io only, should not get full sync slice length.
- */
-static inline u64 cfq_prio_slice(struct cfq_data *cfqd, bool sync,
-				 unsigned short prio)
-{
-	u64 base_slice = cfqd->cfq_slice[sync];
-	u64 slice = div_u64(base_slice, CFQ_SLICE_SCALE);
-
-	WARN_ON(prio >= IOPRIO_BE_NR);
-
-	return base_slice + (slice * (4 - prio));
-}
-
-static inline u64
-cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
-{
-	return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
-}
-
-/**
- * cfqg_scale_charge - scale disk time charge according to cfqg weight
- * @charge: disk time being charged
- * @vfraction: vfraction of the cfqg, fixed point w/ CFQ_SERVICE_SHIFT
- *
- * Scale @charge according to @vfraction, which is in range (0, 1].  The
- * scaling is inversely proportional.
- *
- * scaled = charge / vfraction
- *
- * The result is also in fixed point w/ CFQ_SERVICE_SHIFT.
- */
-static inline u64 cfqg_scale_charge(u64 charge,
-				    unsigned int vfraction)
-{
-	u64 c = charge << CFQ_SERVICE_SHIFT;	/* make it fixed point */
-
-	/* charge / vfraction */
-	c <<= CFQ_SERVICE_SHIFT;
-	return div_u64(c, vfraction);
-}
-
-static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
-{
-	s64 delta = (s64)(vdisktime - min_vdisktime);
-	if (delta > 0)
-		min_vdisktime = vdisktime;
-
-	return min_vdisktime;
-}
-
-static void update_min_vdisktime(struct cfq_rb_root *st)
-{
-	if (!RB_EMPTY_ROOT(&st->rb.rb_root)) {
-		struct cfq_group *cfqg = rb_entry_cfqg(st->rb.rb_leftmost);
-
-		st->min_vdisktime = max_vdisktime(st->min_vdisktime,
-						  cfqg->vdisktime);
-	}
-}
-
-/*
- * get averaged number of queues of RT/BE priority.
- * average is updated, with a formula that gives more weight to higher numbers,
- * to quickly follows sudden increases and decrease slow