zte's code,first commit
Change-Id: I9a04da59e459a9bc0d67f101f700d9d7dc8d681b
diff --git a/ap/os/linux/linux-3.4.x/block/cfq-iosched.c b/ap/os/linux/linux-3.4.x/block/cfq-iosched.c
new file mode 100644
index 0000000..3c38536
--- /dev/null
+++ b/ap/os/linux/linux-3.4.x/block/cfq-iosched.c
@@ -0,0 +1,3936 @@
+/*
+ * 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/blkdev.h>
+#include <linux/elevator.h>
+#include <linux/jiffies.h>
+#include <linux/rbtree.h>
+#include <linux/ioprio.h>
+#include <linux/blktrace_api.h>
+#include "blk.h"
+#include "cfq.h"
+
+/*
+ * tunables
+ */
+/* max queue in one round of service */
+static const int cfq_quantum = 8;
+static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 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 int cfq_slice_sync = HZ / 10;
+static int cfq_slice_async = HZ / 25;
+static const int cfq_slice_async_rq = 2;
+static int cfq_slice_idle = HZ / 125;
+static int cfq_group_idle = HZ / 125;
+static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
+static const int cfq_hist_divisor = 4;
+
+/*
+ * offset from end of service tree
+ */
+#define CFQ_IDLE_DELAY (HZ / 5)
+
+/*
+ * below this threshold, we consider thinktime immediate
+ */
+#define CFQ_MIN_TT (2)
+
+#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)
+
+struct cfq_ttime {
+ unsigned long last_end_request;
+
+ unsigned long ttime_total;
+ unsigned long ttime_samples;
+ unsigned long ttime_mean;
+};
+
+/*
+ * 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 rb;
+ struct rb_node *left;
+ unsigned count;
+ unsigned total_weight;
+ u64 min_vdisktime;
+ struct cfq_ttime ttime;
+};
+#define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \
+ .ttime = {.last_end_request = jiffies,},}
+
+/*
+ * 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 */
+ unsigned long 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. */
+ unsigned long dispatch_start;
+ unsigned int allocated_slice;
+ unsigned int slice_dispatch;
+ /* time when first request from queue completed and slice started. */
+ unsigned long slice_start;
+ unsigned long slice_end;
+ long 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;
+
+ 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_prio_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
+};
+
+/* This is per cgroup per device grouping structure */
+struct cfq_group {
+ /* group service_tree member */
+ struct rb_node rb_node;
+
+ /* group service_tree key */
+ u64 vdisktime;
+ unsigned int weight;
+ unsigned int new_weight;
+ bool needs_update;
+
+ /* 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;
+
+ unsigned long saved_workload_slice;
+ enum wl_type_t saved_workload;
+ enum wl_prio_t saved_serving_prio;
+ struct blkio_group blkg;
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+ struct hlist_node cfqd_node;
+ int ref;
+#endif
+ /* number of requests that are on the dispatch list or inside driver */
+ int dispatched;
+ struct cfq_ttime ttime;
+};
+
+struct cfq_io_cq {
+ struct io_cq icq; /* must be the first member */
+ struct cfq_queue *cfqq[2];
+ struct cfq_ttime ttime;
+};
+
+/*
+ * 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_prio_t serving_prio;
+ enum wl_type_t serving_type;
+ unsigned long 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 timer_list idle_slice_timer;
+ struct work_struct unplug_work;
+
+ struct cfq_queue *active_queue;
+ struct cfq_io_cq *active_cic;
+
+ /*
+ * async queue for each priority case
+ */
+ struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
+ struct cfq_queue *async_idle_cfqq;
+
+ sector_t last_position;
+
+ /*
+ * tunables, see top of file
+ */
+ unsigned int cfq_quantum;
+ unsigned int cfq_fifo_expire[2];
+ unsigned int cfq_back_penalty;
+ unsigned int cfq_back_max;
+ unsigned int cfq_slice[2];
+ unsigned int cfq_slice_async_rq;
+ unsigned int cfq_slice_idle;
+ unsigned int cfq_group_idle;
+ unsigned int cfq_latency;
+ unsigned int cfq_target_latency;
+
+ /*
+ * Fallback dummy cfqq for extreme OOM conditions
+ */
+ struct cfq_queue oom_cfqq;
+
+ unsigned long last_delayed_sync;
+
+ /* List of cfq groups being managed on this device*/
+ struct hlist_head cfqg_list;
+
+ /* Number of groups which are on blkcg->blkg_list */
+ unsigned int nr_blkcg_linked_grps;
+};
+
+static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
+
+static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
+ enum wl_prio_t prio,
+ enum wl_type_t type)
+{
+ if (!cfqg)
+ return NULL;
+
+ if (prio == IDLE_WORKLOAD)
+ return &cfqg->service_tree_idle;
+
+ return &cfqg->service_trees[prio][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
+
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
+ blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
+ cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
+ blkg_path(&(cfqq)->cfqg->blkg), ##args)
+
+#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
+ blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
+ blkg_path(&(cfqg)->blkg), ##args) \
+
+#else
+#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
+ blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
+#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0)
+#endif
+#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)
+{
+ unsigned long 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_prio_t cfqq_prio(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_prio_t wl,
+ struct cfq_data *cfqd,
+ struct cfq_group *cfqg)
+{
+ if (wl == IDLE_WORKLOAD)
+ return cfqg->service_tree_idle.count;
+
+ return cfqg->service_trees[wl][ASYNC_WORKLOAD].count
+ + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
+ + cfqg->service_trees[wl][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 *, bool,
+ struct io_context *, gfp_t);
+
+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;
+}
+
+/*
+ * We regard a request as SYNC, if it's either a read or has the SYNC bit
+ * set (in which case it could also be direct WRITE).
+ */
+static inline bool cfq_bio_sync(struct bio *bio)
+{
+ return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
+}
+
+/*
+ * 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->queue, &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 int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
+ unsigned short prio)
+{
+ const int base_slice = cfqd->cfq_slice[sync];
+
+ WARN_ON(prio >= IOPRIO_BE_NR);
+
+ return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
+}
+
+static inline int
+cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+ return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
+}
+
+static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
+{
+ u64 d = delta << CFQ_SERVICE_SHIFT;
+
+ d = d * BLKIO_WEIGHT_DEFAULT;
+ do_div(d, cfqg->weight);
+ return d;
+}
+
+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 inline u64 min_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)
+{
+ struct cfq_group *cfqg;
+
+ if (st->left) {
+ cfqg = rb_entry_cfqg(st->left);
+ 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 slowly
+ */
+
+static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
+ struct cfq_group *cfqg, bool rt)
+{
+ unsigned min_q, max_q;
+ unsigned mult = cfq_hist_divisor - 1;
+ unsigned round = cfq_hist_divisor / 2;
+ unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
+
+ min_q = min(cfqg->busy_queues_avg[rt], busy);
+ max_q = max(cfqg->busy_queues_avg[rt], busy);
+ cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
+ cfq_hist_divisor;
+ return cfqg->busy_queues_avg[rt];
+}
+
+static inline unsigned
+cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
+{
+ struct cfq_rb_root *st = &cfqd->grp_service_tree;
+
+ return cfqd->cfq_target_latency * cfqg->weight / st->total_weight;
+}
+
+static inline unsigned
+cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+ unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
+ if (cfqd->cfq_latency) {
+ /*
+ * interested queues (we consider only the ones with the same
+ * priority class in the cfq group)
+ */
+ unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
+ cfq_class_rt(cfqq));
+ unsigned sync_slice = cfqd->cfq_slice[1];
+ unsigned expect_latency = sync_slice * iq;
+ unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
+
+ if (expect_latency > group_slice) {
+ unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
+ /* scale low_slice according to IO priority
+ * and sync vs async */
+ unsigned low_slice =
+ min(slice, base_low_slice * slice / sync_slice);
+ /* the adapted slice value is scaled to fit all iqs
+ * into the target latency */
+ slice = max(slice * group_slice / expect_latency,
+ low_slice);
+ }
+ }
+ return slice;
+}
+
+static inline void
+cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+ unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
+
+ cfqq->slice_start = jiffies;
+ cfqq->slice_end = jiffies + slice;
+ cfqq->allocated_slice = slice;
+ cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
+}
+
+/*
+ * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
+ * isn't valid until the first request from the dispatch is activated
+ * and the slice time set.
+ */
+static inline bool cfq_slice_used(struct cfq_queue *cfqq)
+{
+ if (cfq_cfqq_slice_new(cfqq))
+ return false;
+ if (time_before(jiffies, cfqq->slice_end))
+ return false;
+
+ return true;
+}
+
+/*
+ * Lifted from AS - choose which of rq1 and rq2 that is best served now.
+ * We choose the request that is closest to the head right now. Distance
+ * behind the head is penalized and only allowed to a certain extent.
+ */
+static struct request *
+cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
+{
+ sector_t s1, s2, d1 = 0, d2 = 0;
+ unsigned long back_max;
+#define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
+#define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
+ unsigned wrap = 0; /* bit mask: requests behind the disk head? */
+
+ if (rq1 == NULL || rq1 == rq2)
+ return rq2;
+ if (rq2 == NULL)
+ return rq1;
+
+ if (rq_is_sync(rq1) != rq_is_sync(rq2))
+ return rq_is_sync(rq1) ? rq1 : rq2;
+
+ if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO)
+ return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2;
+
+ s1 = blk_rq_pos(rq1);
+ s2 = blk_rq_pos(rq2);
+
+ /*
+ * by definition, 1KiB is 2 sectors
+ */
+ back_max = cfqd->cfq_back_max * 2;
+
+ /*
+ * Strict one way elevator _except_ in the case where we allow
+ * short backward seeks which are biased as twice the cost of a
+ * similar forward seek.
+ */
+ if (s1 >= last)
+ d1 = s1 - last;
+ else if (s1 + back_max >= last)
+ d1 = (last - s1) * cfqd->cfq_back_penalty;
+ else
+ wrap |= CFQ_RQ1_WRAP;
+
+ if (s2 >= last)
+ d2 = s2 - last;
+ else if (s2 + back_max >= last)
+ d2 = (last - s2) * cfqd->cfq_back_penalty;
+ else
+ wrap |= CFQ_RQ2_WRAP;
+
+ /* Found required data */
+
+ /*
+ * By doing switch() on the bit mask "wrap" we avoid having to
+ * check two variables for all permutations: --> faster!
+ */
+ switch (wrap) {
+ case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
+ if (d1 < d2)
+ return rq1;
+ else if (d2 < d1)
+ return rq2;
+ else {
+ if (s1 >= s2)
+ return rq1;
+ else
+ return rq2;
+ }
+
+ case CFQ_RQ2_WRAP:
+ return rq1;
+ case CFQ_RQ1_WRAP:
+ return rq2;
+ case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
+ default:
+ /*
+ * Since both rqs are wrapped,
+ * start with the one that's further behind head
+ * (--> only *one* back seek required),
+ * since back seek takes more time than forward.
+ */
+ if (s1 <= s2)
+ return rq1;
+ else
+ return rq2;
+ }
+}
+
+/*
+ * The below is leftmost cache rbtree addon
+ */
+static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
+{
+ /* Service tree is empty */
+ if (!root->count)
+ return NULL;
+
+ if (!root->left)
+ root->left = rb_first(&root->rb);
+
+ if (root->left)
+ return rb_entry(root->left, struct cfq_queue, rb_node);
+
+ return NULL;
+}
+
+static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
+{
+ if (!root->left)
+ root->left = rb_first(&root->rb);
+
+ if (root->left)
+ return rb_entry_cfqg(root->left);
+
+ return NULL;
+}
+
+static void rb_erase_init(struct rb_node *n, struct rb_root *root)
+{
+ rb_erase(n, root);
+ RB_CLEAR_NODE(n);
+}
+
+static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
+{
+ if (root->left == n)
+ root->left = NULL;
+ rb_erase_init(n, &root->rb);
+ --root->count;
+}
+
+/*
+ * would be nice to take fifo expire time into account as well
+ */
+static struct request *
+cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
+ struct request *last)
+{
+ struct rb_node *rbnext = rb_next(&last->rb_node);
+ struct rb_node *rbprev = rb_prev(&last->rb_node);
+ struct request *next = NULL, *prev = NULL;
+
+ BUG_ON(RB_EMPTY_NODE(&last->rb_node));
+
+ if (rbprev)
+ prev = rb_entry_rq(rbprev);
+
+ if (rbnext)
+ next = rb_entry_rq(rbnext);
+ else {
+ rbnext = rb_first(&cfqq->sort_list);
+ if (rbnext && rbnext != &last->rb_node)
+ next = rb_entry_rq(rbnext);
+ }
+
+ return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
+}
+
+static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
+ struct cfq_queue *cfqq)
+{
+ /*
+ * just an approximation, should be ok.
+ */
+ return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
+ cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
+}
+
+static inline s64
+cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
+{
+ return cfqg->vdisktime - st->min_vdisktime;
+}
+
+static void
+__cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
+{
+ struct rb_node **node = &st->rb.rb_node;
+ struct rb_node *parent = NULL;
+ struct cfq_group *__cfqg;
+ s64 key = cfqg_key(st, cfqg);
+ int left = 1;
+
+ while (*node != NULL) {
+ parent = *node;
+ __cfqg = rb_entry_cfqg(parent);
+
+ if (key < cfqg_key(st, __cfqg))
+ node = &parent->rb_left;
+ else {
+ node = &parent->rb_right;
+ left = 0;
+ }
+ }
+
+ if (left)
+ st->left = &cfqg->rb_node;
+
+ rb_link_node(&cfqg->rb_node, parent, node);
+ rb_insert_color(&cfqg->rb_node, &st->rb);
+}
+
+static void
+cfq_update_group_weight(struct cfq_group *cfqg)
+{
+ BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
+ if (cfqg->needs_update) {
+ cfqg->weight = cfqg->new_weight;
+ cfqg->needs_update = false;
+ }
+}
+
+static void
+cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
+{
+ BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
+
+ cfq_update_group_weight(cfqg);
+ __cfq_group_service_tree_add(st, cfqg);
+ st->total_weight += cfqg->weight;
+}
+
+static void
+cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
+{
+ struct cfq_rb_root *st = &cfqd->grp_service_tree;
+ struct cfq_group *__cfqg;
+ struct rb_node *n;
+
+ cfqg->nr_cfqq++;
+ if (!RB_EMPTY_NODE(&cfqg->rb_node))
+ return;
+
+ /*
+ * Currently put the group at the end. Later implement something
+ * so that groups get lesser vtime based on their weights, so that
+ * if group does not loose all if it was not continuously backlogged.
+ */
+ n = rb_last(&st->rb);
+ if (n) {
+ __cfqg = rb_entry_cfqg(n);
+ cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
+ } else
+ cfqg->vdisktime = st->min_vdisktime;
+ cfq_group_service_tree_add(st, cfqg);
+}
+
+static void
+cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
+{
+ st->total_weight -= cfqg->weight;
+ if (!RB_EMPTY_NODE(&cfqg->rb_node))
+ cfq_rb_erase(&cfqg->rb_node, st);
+}
+
+static void
+cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
+{
+ struct cfq_rb_root *st = &cfqd->grp_service_tree;
+
+ BUG_ON(cfqg->nr_cfqq < 1);
+ cfqg->nr_cfqq--;
+
+ /* If there are other cfq queues under this group, don't delete it */
+ if (cfqg->nr_cfqq)
+ return;
+
+ cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
+ cfq_group_service_tree_del(st, cfqg);
+ cfqg->saved_workload_slice = 0;
+ cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1);
+}
+
+static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
+ unsigned int *unaccounted_time)
+{
+ unsigned int slice_used;
+
+ /*
+ * Queue got expired before even a single request completed or
+ * got expired immediately after first request completion.
+ */
+ if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
+ /*
+ * Also charge the seek time incurred to the group, otherwise
+ * if there are mutiple queues in the group, each can dispatch
+ * a single request on seeky media and cause lots of seek time
+ * and group will never know it.
+ */
+ slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
+ 1);
+ } else {
+ slice_used = jiffies - cfqq->slice_start;
+ if (slice_used > cfqq->allocated_slice) {
+ *unaccounted_time = slice_used - cfqq->allocated_slice;
+ slice_used = cfqq->allocated_slice;
+ }
+ if (time_after(cfqq->slice_start, cfqq->dispatch_start))
+ *unaccounted_time += cfqq->slice_start -
+ cfqq->dispatch_start;
+ }
+
+ return slice_used;
+}
+
+static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
+ struct cfq_queue *cfqq)
+{
+ struct cfq_rb_root *st = &cfqd->grp_service_tree;
+ unsigned int used_sl, charge, unaccounted_sl = 0;
+ int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
+ - cfqg->service_tree_idle.count;
+
+ BUG_ON(nr_sync < 0);
+ used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
+
+ if (iops_mode(cfqd))
+ charge = cfqq->slice_dispatch;
+ else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
+ charge = cfqq->allocated_slice;
+
+ /* Can't update vdisktime while group is on service tree */
+ cfq_group_service_tree_del(st, cfqg);
+ cfqg->vdisktime += cfq_scale_slice(charge, cfqg);
+ /* If a new weight was requested, update now, off tree */
+ cfq_group_service_tree_add(st, cfqg);
+
+ /* This group is being expired. Save the context */
+ if (time_after(cfqd->workload_expires, jiffies)) {
+ cfqg->saved_workload_slice = cfqd->workload_expires
+ - jiffies;
+ cfqg->saved_workload = cfqd->serving_type;
+ cfqg->saved_serving_prio = cfqd->serving_prio;
+ } else
+ cfqg->saved_workload_slice = 0;
+
+ cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
+ st->min_vdisktime);
+ cfq_log_cfqq(cfqq->cfqd, cfqq,
+ "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
+ used_sl, cfqq->slice_dispatch, charge,
+ iops_mode(cfqd), cfqq->nr_sectors);
+ cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl,
+ unaccounted_sl);
+ cfq_blkiocg_set_start_empty_time(&cfqg->blkg);
+}
+
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
+{
+ if (blkg)
+ return container_of(blkg, struct cfq_group, blkg);
+ return NULL;
+}
+
+static void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg,
+ unsigned int weight)
+{
+ struct cfq_group *cfqg = cfqg_of_blkg(blkg);
+ cfqg->new_weight = weight;
+ cfqg->needs_update = true;
+}
+
+static void cfq_init_add_cfqg_lists(struct cfq_data *cfqd,
+ struct cfq_group *cfqg, struct blkio_cgroup *blkcg)
+{
+ struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
+ unsigned int major, minor;
+
+ /*
+ * Add group onto cgroup list. It might happen that bdi->dev is
+ * not initialized yet. Initialize this new group without major
+ * and minor info and this info will be filled in once a new thread
+ * comes for IO.
+ */
+ if (bdi->dev) {
+ sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
+ cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg,
+ (void *)cfqd, MKDEV(major, minor));
+ } else
+ cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg,
+ (void *)cfqd, 0);
+
+ cfqd->nr_blkcg_linked_grps++;
+ cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev);
+
+ /* Add group on cfqd list */
+ hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
+}
+
+/*
+ * Should be called from sleepable context. No request queue lock as per
+ * cpu stats are allocated dynamically and alloc_percpu needs to be called
+ * from sleepable context.
+ */
+static struct cfq_group * cfq_alloc_cfqg(struct cfq_data *cfqd)
+{
+ struct cfq_group *cfqg = NULL;
+ int i, j, ret;
+ struct cfq_rb_root *st;
+
+ cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
+ if (!cfqg)
+ return NULL;
+
+ for_each_cfqg_st(cfqg, i, j, st)
+ *st = CFQ_RB_ROOT;
+ RB_CLEAR_NODE(&cfqg->rb_node);
+
+ cfqg->ttime.last_end_request = jiffies;
+
+ /*
+ * Take the initial reference that will be released on destroy
+ * This can be thought of a joint reference by cgroup and
+ * elevator which will be dropped by either elevator exit
+ * or cgroup deletion path depending on who is exiting first.
+ */
+ cfqg->ref = 1;
+
+ ret = blkio_alloc_blkg_stats(&cfqg->blkg);
+ if (ret) {
+ kfree(cfqg);
+ return NULL;
+ }
+
+ return cfqg;
+}
+
+static struct cfq_group *
+cfq_find_cfqg(struct cfq_data *cfqd, struct blkio_cgroup *blkcg)
+{
+ struct cfq_group *cfqg = NULL;
+ void *key = cfqd;
+ struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
+ unsigned int major, minor;
+
+ /*
+ * This is the common case when there are no blkio cgroups.
+ * Avoid lookup in this case
+ */
+ if (blkcg == &blkio_root_cgroup)
+ cfqg = &cfqd->root_group;
+ else
+ cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
+
+ if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
+ sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
+ cfqg->blkg.dev = MKDEV(major, minor);
+ }
+
+ return cfqg;
+}
+
+/*
+ * Search for the cfq group current task belongs to. request_queue lock must
+ * be held.
+ */
+static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd)
+{
+ struct blkio_cgroup *blkcg;
+ struct cfq_group *cfqg = NULL, *__cfqg = NULL;
+ struct request_queue *q = cfqd->queue;
+
+ rcu_read_lock();
+ blkcg = task_blkio_cgroup(current);
+ cfqg = cfq_find_cfqg(cfqd, blkcg);
+ if (cfqg) {
+ rcu_read_unlock();
+ return cfqg;
+ }
+
+ /*
+ * Need to allocate a group. Allocation of group also needs allocation
+ * of per cpu stats which in-turn takes a mutex() and can block. Hence
+ * we need to drop rcu lock and queue_lock before we call alloc.
+ *
+ * Not taking any queue reference here and assuming that queue is
+ * around by the time we return. CFQ queue allocation code does
+ * the same. It might be racy though.
+ */
+
+ rcu_read_unlock();
+ spin_unlock_irq(q->queue_lock);
+
+ cfqg = cfq_alloc_cfqg(cfqd);
+
+ spin_lock_irq(q->queue_lock);
+
+ rcu_read_lock();
+ blkcg = task_blkio_cgroup(current);
+
+ /*
+ * If some other thread already allocated the group while we were
+ * not holding queue lock, free up the group
+ */
+ __cfqg = cfq_find_cfqg(cfqd, blkcg);
+
+ if (__cfqg) {
+ kfree(cfqg);
+ rcu_read_unlock();
+ return __cfqg;
+ }
+
+ if (!cfqg)
+ cfqg = &cfqd->root_group;
+
+ cfq_init_add_cfqg_lists(cfqd, cfqg, blkcg);
+ rcu_read_unlock();
+ return cfqg;
+}
+
+static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
+{
+ cfqg->ref++;
+ return cfqg;
+}
+
+static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
+{
+ /* Currently, all async queues are mapped to root group */
+ if (!cfq_cfqq_sync(cfqq))
+ cfqg = &cfqq->cfqd->root_group;
+
+ cfqq->cfqg = cfqg;
+ /* cfqq reference on cfqg */
+ cfqq->cfqg->ref++;
+}
+
+static void cfq_put_cfqg(struct cfq_group *cfqg)
+{
+ struct cfq_rb_root *st;
+ int i, j;
+
+ BUG_ON(cfqg->ref <= 0);
+ cfqg->ref--;
+ if (cfqg->ref)
+ return;
+ for_each_cfqg_st(cfqg, i, j, st)
+ BUG_ON(!RB_EMPTY_ROOT(&st->rb));
+ free_percpu(cfqg->blkg.stats_cpu);
+ kfree(cfqg);
+}
+
+static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
+{
+ /* Something wrong if we are trying to remove same group twice */
+ BUG_ON(hlist_unhashed(&cfqg->cfqd_node));
+
+ hlist_del_init(&cfqg->cfqd_node);
+
+ BUG_ON(cfqd->nr_blkcg_linked_grps <= 0);
+ cfqd->nr_blkcg_linked_grps--;
+
+ /*
+ * Put the reference taken at the time of creation so that when all
+ * queues are gone, group can be destroyed.
+ */
+ cfq_put_cfqg(cfqg);
+}
+
+static void cfq_release_cfq_groups(struct cfq_data *cfqd)
+{
+ struct hlist_node *pos, *n;
+ struct cfq_group *cfqg;
+
+ hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) {
+ /*
+ * If cgroup removal path got to blk_group first and removed
+ * it from cgroup list, then it will take care of destroying
+ * cfqg also.
+ */
+ if (!cfq_blkiocg_del_blkio_group(&cfqg->blkg))
+ cfq_destroy_cfqg(cfqd, cfqg);
+ }
+}
+
+/*
+ * Blk cgroup controller notification saying that blkio_group object is being
+ * delinked as associated cgroup object is going away. That also means that
+ * no new IO will come in this group. So get rid of this group as soon as
+ * any pending IO in the group is finished.
+ *
+ * This function is called under rcu_read_lock(). key is the rcu protected
+ * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
+ * read lock.
+ *
+ * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
+ * it should not be NULL as even if elevator was exiting, cgroup deltion
+ * path got to it first.
+ */
+static void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
+{
+ unsigned long flags;
+ struct cfq_data *cfqd = key;
+
+ spin_lock_irqsave(cfqd->queue->queue_lock, flags);
+ cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg));
+ spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
+}
+
+#else /* GROUP_IOSCHED */
+static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd)
+{
+ return &cfqd->root_group;
+}
+
+static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
+{
+ return cfqg;
+}
+
+static inline void
+cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
+ cfqq->cfqg = cfqg;
+}
+
+static void cfq_release_cfq_groups(struct cfq_data *cfqd) {}
+static inline void cfq_put_cfqg(struct cfq_group *cfqg) {}
+
+#endif /* GROUP_IOSCHED */
+
+/*
+ * The cfqd->service_trees holds all pending cfq_queue's that have
+ * requests waiting to be processed. It is sorted in the order that
+ * we will service the queues.
+ */
+static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
+ bool add_front)
+{
+ struct rb_node **p, *parent;
+ struct cfq_queue *__cfqq;
+ unsigned long rb_key;
+ struct cfq_rb_root *service_tree;
+ int left;
+ int new_cfqq = 1;
+
+ service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
+ cfqq_type(cfqq));
+ if (cfq_class_idle(cfqq)) {
+ rb_key = CFQ_IDLE_DELAY;
+ parent = rb_last(&service_tree->rb);
+ if (parent && parent != &cfqq->rb_node) {
+ __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
+ rb_key += __cfqq->rb_key;
+ } else
+ rb_key += jiffies;
+ } else if (!add_front) {
+ /*
+ * Get our rb key offset. Subtract any residual slice
+ * value carried from last service. A negative resid
+ * count indicates slice overrun, and this should position
+ * the next service time further away in the tree.
+ */
+ rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
+ rb_key -= cfqq->slice_resid;
+ cfqq->slice_resid = 0;
+ } else {
+ rb_key = -HZ;
+ __cfqq = cfq_rb_first(service_tree);
+ rb_key += __cfqq ? __cfqq->rb_key : jiffies;
+ }
+
+ if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
+ new_cfqq = 0;
+ /*
+ * same position, nothing more to do
+ */
+ if (rb_key == cfqq->rb_key &&
+ cfqq->service_tree == service_tree)
+ return;
+
+ cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
+ cfqq->service_tree = NULL;
+ }
+
+ left = 1;
+ parent = NULL;
+ cfqq->service_tree = service_tree;
+ p = &service_tree->rb.rb_node;
+ while (*p) {
+ struct rb_node **n;
+
+ parent = *p;
+ __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
+
+ /*
+ * sort by key, that represents service time.
+ */
+ if (time_before(rb_key, __cfqq->rb_key))
+ n = &(*p)->rb_left;
+ else {
+ n = &(*p)->rb_right;
+ left = 0;
+ }
+
+ p = n;
+ }
+
+ if (left)
+ service_tree->left = &cfqq->rb_node;
+
+ cfqq->rb_key = rb_key;
+ rb_link_node(&cfqq->rb_node, parent, p);
+ rb_insert_color(&cfqq->rb_node, &service_tree->rb);
+ service_tree->count++;
+ if (add_front || !new_cfqq)
+ return;
+ cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
+}
+
+static struct cfq_queue *
+cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
+ sector_t sector, struct rb_node **ret_parent,
+ struct rb_node ***rb_link)
+{
+ struct rb_node **p, *parent;
+ struct cfq_queue *cfqq = NULL;
+
+ parent = NULL;
+ p = &root->rb_node;
+ while (*p) {
+ struct rb_node **n;
+
+ parent = *p;
+ cfqq = rb_entry(parent, struct cfq_queue, p_node);
+
+ /*
+ * Sort strictly based on sector. Smallest to the left,
+ * largest to the right.
+ */
+ if (sector > blk_rq_pos(cfqq->next_rq))
+ n = &(*p)->rb_right;
+ else if (sector < blk_rq_pos(cfqq->next_rq))
+ n = &(*p)->rb_left;
+ else
+ break;
+ p = n;
+ cfqq = NULL;
+ }
+
+ *ret_parent = parent;
+ if (rb_link)
+ *rb_link = p;
+ return cfqq;
+}
+
+static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+ struct rb_node **p, *parent;
+ struct cfq_queue *__cfqq;
+
+ if (cfqq->p_root) {
+ rb_erase(&cfqq->p_node, cfqq->p_root);
+ cfqq->p_root = NULL;
+ }
+
+ if (cfq_class_idle(cfqq))
+ return;
+ if (!cfqq->next_rq)
+ return;
+
+ cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
+ __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
+ blk_rq_pos(cfqq->next_rq), &parent, &p);
+ if (!__cfqq) {
+ rb_link_node(&cfqq->p_node, parent, p);
+ rb_insert_color(&cfqq->p_node, cfqq->p_root);
+ } else
+ cfqq->p_root = NULL;
+}
+
+/*
+ * Update cfqq's position in the service tree.
+ */
+static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+ /*
+ * Resorting requires the cfqq to be on the RR list already.
+ */
+ if (cfq_cfqq_on_rr(cfqq)) {
+ cfq_service_tree_add(cfqd, cfqq, 0);
+ cfq_prio_tree_add(cfqd, cfqq);
+ }
+}
+
+/*
+ * add to busy list of queues for service, trying to be fair in ordering
+ * the pending list according to last request service
+ */
+static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+ cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
+ BUG_ON(cfq_cfqq_on_rr(cfqq));
+ cfq_mark_cfqq_on_rr(cfqq);
+ cfqd->busy_queues++;
+ if (cfq_cfqq_sync(cfqq))
+ cfqd->busy_sync_queues++;
+
+ cfq_resort_rr_list(cfqd, cfqq);
+}
+
+/*
+ * Called when the cfqq no longer has requests pending, remove it from
+ * the service tree.
+ */
+static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+ cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
+ BUG_ON(!cfq_cfqq_on_rr(cfqq));
+ cfq_clear_cfqq_on_rr(cfqq);
+
+ if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
+ cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
+ cfqq->service_tree = NULL;
+ }
+ if (cfqq->p_root) {
+ rb_erase(&cfqq->p_node, cfqq->p_root);
+ cfqq->p_root = NULL;
+ }
+
+ cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
+ BUG_ON(!cfqd->busy_queues);
+ cfqd->busy_queues--;
+ if (cfq_cfqq_sync(cfqq))
+ cfqd->busy_sync_queues--;
+}
+
+/*
+ * rb tree support functions
+ */
+static void cfq_del_rq_rb(struct request *rq)
+{
+ struct cfq_queue *cfqq = RQ_CFQQ(rq);
+ const int sync = rq_is_sync(rq);
+
+ BUG_ON(!cfqq->queued[sync]);
+ cfqq->queued[sync]--;
+
+ elv_rb_del(&cfqq->sort_list, rq);
+
+ if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
+ /*
+ * Queue will be deleted from service tree when we actually
+ * expire it later. Right now just remove it from prio tree
+ * as it is empty.
+ */
+ if (cfqq->p_root) {
+ rb_erase(&cfqq->p_node, cfqq->p_root);
+ cfqq->p_root = NULL;
+ }
+ }
+}
+
+static void cfq_add_rq_rb(struct request *rq)
+{
+ struct cfq_queue *cfqq = RQ_CFQQ(rq);
+ struct cfq_data *cfqd = cfqq->cfqd;
+ struct request *prev;
+
+ cfqq->queued[rq_is_sync(rq)]++;
+
+ elv_rb_add(&cfqq->sort_list, rq);
+
+ if (!cfq_cfqq_on_rr(cfqq))
+ cfq_add_cfqq_rr(cfqd, cfqq);
+
+ /*
+ * check if this request is a better next-serve candidate
+ */
+ prev = cfqq->next_rq;
+ cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
+
+ /*
+ * adjust priority tree position, if ->next_rq changes
+ */
+ if (prev != cfqq->next_rq)
+ cfq_prio_tree_add(cfqd, cfqq);
+
+ BUG_ON(!cfqq->next_rq);
+}
+
+static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
+{
+ elv_rb_del(&cfqq->sort_list, rq);
+ cfqq->queued[rq_is_sync(rq)]--;
+ cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
+ rq_data_dir(rq), rq_is_sync(rq));
+ cfq_add_rq_rb(rq);
+ cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
+ &cfqq->cfqd->serving_group->blkg, rq_data_dir(rq),
+ rq_is_sync(rq));
+}
+
+static struct request *
+cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
+{
+ struct task_struct *tsk = current;
+ struct cfq_io_cq *cic;
+ struct cfq_queue *cfqq;
+
+ cic = cfq_cic_lookup(cfqd, tsk->io_context);
+ if (!cic)
+ return NULL;
+
+ cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
+ if (cfqq) {
+ sector_t sector = bio->bi_sector + bio_sectors(bio);
+
+ return elv_rb_find(&cfqq->sort_list, sector);
+ }
+
+ return NULL;
+}
+
+static void cfq_activate_request(struct request_queue *q, struct request *rq)
+{
+ struct cfq_data *cfqd = q->elevator->elevator_data;
+
+ cfqd->rq_in_driver++;
+ cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
+ cfqd->rq_in_driver);
+
+ cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
+}
+
+static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
+{
+ struct cfq_data *cfqd = q->elevator->elevator_data;
+
+ WARN_ON(!cfqd->rq_in_driver);
+ cfqd->rq_in_driver--;
+ cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
+ cfqd->rq_in_driver);
+}
+
+static void cfq_remove_request(struct request *rq)
+{
+ struct cfq_queue *cfqq = RQ_CFQQ(rq);
+
+ if (cfqq->next_rq == rq)
+ cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
+
+ list_del_init(&rq->queuelist);
+ cfq_del_rq_rb(rq);
+
+ cfqq->cfqd->rq_queued--;
+ cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
+ rq_data_dir(rq), rq_is_sync(rq));
+ if (rq->cmd_flags & REQ_PRIO) {
+ WARN_ON(!cfqq->prio_pending);
+ cfqq->prio_pending--;
+ }
+}
+
+static int cfq_merge(struct request_queue *q, struct request **req,
+ struct bio *bio)
+{
+ struct cfq_data *cfqd = q->elevator->elevator_data;
+ struct request *__rq;
+
+ __rq = cfq_find_rq_fmerge(cfqd, bio);
+ if (__rq && elv_rq_merge_ok(__rq, bio)) {
+ *req = __rq;
+ return ELEVATOR_FRONT_MERGE;
+ }
+
+ return ELEVATOR_NO_MERGE;
+}
+
+static void cfq_merged_request(struct request_queue *q, struct request *req,
+ int type)
+{
+ if (type == ELEVATOR_FRONT_MERGE) {
+ struct cfq_queue *cfqq = RQ_CFQQ(req);
+
+ cfq_reposition_rq_rb(cfqq, req);
+ }
+}
+
+static void cfq_bio_merged(struct request_queue *q, struct request *req,
+ struct bio *bio)
+{
+ cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg,
+ bio_data_dir(bio), cfq_bio_sync(bio));
+}
+
+static void
+cfq_merged_requests(struct request_queue *q, struct request *rq,
+ struct request *next)
+{
+ struct cfq_queue *cfqq = RQ_CFQQ(rq);
+ struct cfq_data *cfqd = q->elevator->elevator_data;
+
+ /*
+ * reposition in fifo if next is older than rq
+ */
+ if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
+ time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
+ list_move(&rq->queuelist, &next->queuelist);
+ rq_set_fifo_time(rq, rq_fifo_time(next));
+ }
+
+ if (cfqq->next_rq == next)
+ cfqq->next_rq = rq;
+ cfq_remove_request(next);
+ cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg,
+ rq_data_dir(next), rq_is_sync(next));
+
+ cfqq = RQ_CFQQ(next);
+ /*
+ * all requests of this queue are merged to other queues, delete it
+ * from the service tree. If it's the active_queue,
+ * cfq_dispatch_requests() will choose to expire it or do idle
+ */
+ if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) &&
+ cfqq != cfqd->active_queue)
+ cfq_del_cfqq_rr(cfqd, cfqq);
+}
+
+static int cfq_allow_merge(struct request_queue *q, struct request *rq,
+ struct bio *bio)
+{
+ struct cfq_data *cfqd = q->elevator->elevator_data;
+ struct cfq_io_cq *cic;
+ struct cfq_queue *cfqq;
+
+ /*
+ * Disallow merge of a sync bio into an async request.
+ */
+ if (cfq_bio_sync(bio) && !rq_is_sync(rq))
+ return false;
+
+ /*
+ * Lookup the cfqq that this bio will be queued with and allow
+ * merge only if rq is queued there.
+ */
+ cic = cfq_cic_lookup(cfqd, current->io_context);
+ if (!cic)
+ return false;
+
+ cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
+ return cfqq == RQ_CFQQ(rq);
+}
+
+static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+ del_timer(&cfqd->idle_slice_timer);
+ cfq_blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg);
+}
+
+static void __cfq_set_active_queue(struct cfq_data *cfqd,
+ struct cfq_queue *cfqq)
+{
+ if (cfqq) {
+ cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d",
+ cfqd->serving_prio, cfqd->serving_type);
+ cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg);
+ cfqq->slice_start = 0;
+ cfqq->dispatch_start = jiffies;
+ cfqq->allocated_slice = 0;
+ cfqq->slice_end = 0;
+ cfqq->slice_dispatch = 0;
+ cfqq->nr_sectors = 0;
+
+ cfq_clear_cfqq_wait_request(cfqq);
+ cfq_clear_cfqq_must_dispatch(cfqq);
+ cfq_clear_cfqq_must_alloc_slice(cfqq);
+ cfq_clear_cfqq_fifo_expire(cfqq);
+ cfq_mark_cfqq_slice_new(cfqq);
+
+ cfq_del_timer(cfqd, cfqq);
+ }
+
+ cfqd->active_queue = cfqq;
+}
+
+/*
+ * current cfqq expired its slice (or was too idle), select new one
+ */
+static void
+__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
+ bool timed_out)
+{
+ cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
+
+ if (cfq_cfqq_wait_request(cfqq))
+ cfq_del_timer(cfqd, cfqq);
+
+ cfq_clear_cfqq_wait_request(cfqq);
+ cfq_clear_cfqq_wait_busy(cfqq);
+
+ /*
+ * If this cfqq is shared between multiple processes, check to
+ * make sure that those processes are still issuing I/Os within
+ * the mean seek distance. If not, it may be time to break the
+ * queues apart again.
+ */
+ if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
+ cfq_mark_cfqq_split_coop(cfqq);
+
+ /*
+ * store what was left of this slice, if the queue idled/timed out
+ */
+ if (timed_out) {
+ if (cfq_cfqq_slice_new(cfqq))
+ cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
+ else
+ cfqq->slice_resid = cfqq->slice_end - jiffies;
+ cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
+ }
+
+ cfq_group_served(cfqd, cfqq->cfqg, cfqq);
+
+ if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
+ cfq_del_cfqq_rr(cfqd, cfqq);
+
+ cfq_resort_rr_list(cfqd, cfqq);
+
+ if (cfqq == cfqd->active_queue)
+ cfqd->active_queue = NULL;
+
+ if (cfqd->active_cic) {
+ put_io_context(cfqd->active_cic->icq.ioc);
+ cfqd->active_cic = NULL;
+ }
+}
+
+static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
+{
+ struct cfq_queue *cfqq = cfqd->active_queue;
+
+ if (cfqq)
+ __cfq_slice_expired(cfqd, cfqq, timed_out);
+}
+
+/*
+ * Get next queue for service. Unless we have a queue preemption,
+ * we'll simply select the first cfqq in the service tree.
+ */
+static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
+{
+ struct cfq_rb_root *service_tree =
+ service_tree_for(cfqd->serving_group, cfqd->serving_prio,
+ cfqd->serving_type);
+
+ if (!cfqd->rq_queued)
+ return NULL;
+
+ /* There is nothing to dispatch */
+ if (!service_tree)
+ return NULL;
+ if (RB_EMPTY_ROOT(&service_tree->rb))
+ return NULL;
+ return cfq_rb_first(service_tree);
+}
+
+static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
+{
+ struct cfq_group *cfqg;
+ struct cfq_queue *cfqq;
+ int i, j;
+ struct cfq_rb_root *st;
+
+ if (!cfqd->rq_queued)
+ return NULL;
+
+ cfqg = cfq_get_next_cfqg(cfqd);
+ if (!cfqg)
+ return NULL;
+
+ for_each_cfqg_st(cfqg, i, j, st)
+ if ((cfqq = cfq_rb_first(st)) != NULL)
+ return cfqq;
+ return NULL;
+}
+
+/*
+ * Get and set a new active queue for service.
+ */
+static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
+ struct cfq_queue *cfqq)
+{
+ if (!cfqq)
+ cfqq = cfq_get_next_queue(cfqd);
+
+ __cfq_set_active_queue(cfqd, cfqq);
+ return cfqq;
+}
+
+static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
+ struct request *rq)
+{
+ if (blk_rq_pos(rq) >= cfqd->last_position)
+ return blk_rq_pos(rq) - cfqd->last_position;
+ else
+ return cfqd->last_position - blk_rq_pos(rq);
+}
+
+static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
+ struct request *rq)
+{
+ return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
+}
+
+static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
+ struct cfq_queue *cur_cfqq)
+{
+ struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
+ struct rb_node *parent, *node;
+ struct cfq_queue *__cfqq;
+ sector_t sector = cfqd->last_position;
+
+ if (RB_EMPTY_ROOT(root))
+ return NULL;
+
+ /*
+ * First, if we find a request starting at the end of the last
+ * request, choose it.
+ */
+ __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
+ if (__cfqq)
+ return __cfqq;
+
+ /*
+ * If the exact sector wasn't found, the parent of the NULL leaf
+ * will contain the closest sector.
+ */
+ __cfqq = rb_entry(parent, struct cfq_queue, p_node);
+ if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
+ return __cfqq;
+
+ if (blk_rq_pos(__cfqq->next_rq) < sector)
+ node = rb_next(&__cfqq->p_node);
+ else
+ node = rb_prev(&__cfqq->p_node);
+ if (!node)
+ return NULL;
+
+ __cfqq = rb_entry(node, struct cfq_queue, p_node);
+ if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
+ return __cfqq;
+
+ return NULL;
+}
+
+/*
+ * cfqd - obvious
+ * cur_cfqq - passed in so that we don't decide that the current queue is
+ * closely cooperating with itself.
+ *
+ * So, basically we're assuming that that cur_cfqq has dispatched at least
+ * one request, and that cfqd->last_position reflects a position on the disk
+ * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
+ * assumption.
+ */
+static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
+ struct cfq_queue *cur_cfqq)
+{
+ struct cfq_queue *cfqq;
+
+ if (cfq_class_idle(cur_cfqq))
+ return NULL;
+ if (!cfq_cfqq_sync(cur_cfqq))
+ return NULL;
+ if (CFQQ_SEEKY(cur_cfqq))
+ return NULL;
+
+ /*
+ * Don't search priority tree if it's the only queue in the group.
+ */
+ if (cur_cfqq->cfqg->nr_cfqq == 1)
+ return NULL;
+
+ /*
+ * We should notice if some of the queues are cooperating, eg
+ * working closely on the same area of the disk. In that case,
+ * we can group them together and don't waste time idling.
+ */
+ cfqq = cfqq_close(cfqd, cur_cfqq);
+ if (!cfqq)
+ return NULL;
+
+ /* If new queue belongs to different cfq_group, don't choose it */
+ if (cur_cfqq->cfqg != cfqq->cfqg)
+ return NULL;
+
+ /*
+ * It only makes sense to merge sync queues.
+ */
+ if (!cfq_cfqq_sync(cfqq))
+ return NULL;
+ if (CFQQ_SEEKY(cfqq))
+ return NULL;
+
+ /*
+ * Do not merge queues of different priority classes
+ */
+ if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
+ return NULL;
+
+ return cfqq;
+}
+
+/*
+ * Determine whether we should enforce idle window for this queue.
+ */
+
+static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+ enum wl_prio_t prio = cfqq_prio(cfqq);
+ struct cfq_rb_root *service_tree = cfqq->service_tree;
+
+ BUG_ON(!service_tree);
+ BUG_ON(!service_tree->count);
+
+ if (!cfqd->cfq_slice_idle)
+ return false;
+
+ /* We never do for idle class queues. */
+ if (prio == IDLE_WORKLOAD)
+ return false;
+
+ /* We do for queues that were marked with idle window flag. */
+ if (cfq_cfqq_idle_window(cfqq) &&
+ !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
+ return true;
+
+ /*
+ * Otherwise, we do only if they are the last ones
+ * in their service tree.
+ */
+ if (service_tree->count == 1 && cfq_cfqq_sync(cfqq) &&
+ !cfq_io_thinktime_big(cfqd, &service_tree->ttime, false))
+ return true;
+ cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
+ service_tree->count);
+ return false;
+}
+
+static void cfq_arm_slice_timer(struct cfq_data *cfqd)
+{
+ struct cfq_queue *cfqq = cfqd->active_queue;
+ struct cfq_io_cq *cic;
+ unsigned long sl, group_idle = 0;
+
+ /*
+ * SSD device without seek penalty, disable idling. But only do so
+ * for devices that support queuing, otherwise we still have a problem
+ * with sync vs async workloads.
+ */
+ if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
+ return;
+
+ WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
+ WARN_ON(cfq_cfqq_slice_new(cfqq));
+
+ /*
+ * idle is disabled, either manually or by past process history
+ */
+ if (!cfq_should_idle(cfqd, cfqq)) {
+ /* no queue idling. Check for group idling */
+ if (cfqd->cfq_group_idle)
+ group_idle = cfqd->cfq_group_idle;
+ else
+ return;
+ }
+
+ /*
+ * still active requests from this queue, don't idle
+ */
+ if (cfqq->dispatched)
+ return;
+
+ /*
+ * task has exited, don't wait
+ */
+ cic = cfqd->active_cic;
+ if (!cic || !atomic_read(&cic->icq.ioc->nr_tasks))
+ return;
+
+ /*
+ * If our average think time is larger than the remaining time
+ * slice, then don't idle. This avoids overrunning the allotted
+ * time slice.
+ */
+ if (sample_valid(cic->ttime.ttime_samples) &&
+ (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) {
+ cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu",
+ cic->ttime.ttime_mean);
+ return;
+ }
+
+ /* There are other queues in the group, don't do group idle */
+ if (group_idle && cfqq->cfqg->nr_cfqq > 1)
+ return;
+
+ cfq_mark_cfqq_wait_request(cfqq);
+
+ if (group_idle)
+ sl = cfqd->cfq_group_idle;
+ else
+ sl = cfqd->cfq_slice_idle;
+
+ mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
+ cfq_blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg);
+ cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
+ group_idle ? 1 : 0);
+}
+
+/*
+ * Move request from internal lists to the request queue dispatch list.
+ */
+static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
+{
+ struct cfq_data *cfqd = q->elevator->elevator_data;
+ struct cfq_queue *cfqq = RQ_CFQQ(rq);
+
+ cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
+
+ cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
+ cfq_remove_request(rq);
+ cfqq->dispatched++;
+ (RQ_CFQG(rq))->dispatched++;
+ elv_dispatch_sort(q, rq);
+
+ cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
+ cfqq->nr_sectors += blk_rq_sectors(rq);
+ cfq_blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq),
+ rq_data_dir(rq), rq_is_sync(rq));
+}
+
+/*
+ * return expired entry, or NULL to just start from scratch in rbtree
+ */
+static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
+{
+ struct request *rq = NULL;
+
+ if (cfq_cfqq_fifo_expire(cfqq))
+ return NULL;
+
+ cfq_mark_cfqq_fifo_expire(cfqq);
+
+ if (list_empty(&cfqq->fifo))
+ return NULL;
+
+ rq = rq_entry_fifo(cfqq->fifo.next);
+ if (time_before(jiffies, rq_fifo_time(rq)))
+ rq = NULL;
+
+ cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
+ return rq;
+}
+
+static inline int
+cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+ const int base_rq = cfqd->cfq_slice_async_rq;
+
+ WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
+
+ return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
+}
+
+/*
+ * Must be called with the queue_lock held.
+ */
+static int cfqq_process_refs(struct cfq_queue *cfqq)
+{
+ int process_refs, io_refs;
+
+ io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
+ process_refs = cfqq->ref - io_refs;
+ BUG_ON(process_refs < 0);
+ return process_refs;
+}
+
+static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
+{
+ int process_refs, new_process_refs;
+ struct cfq_queue *__cfqq;
+
+ /*
+ * If there are no process references on the new_cfqq, then it is
+ * unsafe to follow the ->new_cfqq chain as other cfqq's in the
+ * chain may have dropped their last reference (not just their
+ * last process reference).
+ */
+ if (!cfqq_process_refs(new_cfqq))
+ return;
+
+ /* Avoid a circular list and skip interim queue merges */
+ while ((__cfqq = new_cfqq->new_cfqq)) {
+ if (__cfqq == cfqq)
+ return;
+ new_cfqq = __cfqq;
+ }
+
+ process_refs = cfqq_process_refs(cfqq);
+ new_process_refs = cfqq_process_refs(new_cfqq);
+ /*
+ * If the process for the cfqq has gone away, there is no
+ * sense in merging the queues.
+ */
+ if (process_refs == 0 || new_process_refs == 0)
+ return;
+
+ /*
+ * Merge in the direction of the lesser amount of work.
+ */
+ if (new_process_refs >= process_refs) {
+ cfqq->new_cfqq = new_cfqq;
+ new_cfqq->ref += process_refs;
+ } else {
+ new_cfqq->new_cfqq = cfqq;
+ cfqq->ref += new_process_refs;
+ }
+}
+
+static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
+ struct cfq_group *cfqg, enum wl_prio_t prio)
+{
+ struct cfq_queue *queue;
+ int i;
+ bool key_valid = false;
+ unsigned long lowest_key = 0;
+ enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
+
+ for (i = 0; i <= SYNC_WORKLOAD; ++i) {
+ /* select the one with lowest rb_key */
+ queue = cfq_rb_first(service_tree_for(cfqg, prio, i));
+ if (queue &&
+ (!key_valid || time_before(queue->rb_key, lowest_key))) {
+ lowest_key = queue->rb_key;
+ cur_best = i;
+ key_valid = true;
+ }
+ }
+
+ return cur_best;
+}
+
+static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
+{
+ unsigned slice;
+ unsigned count;
+ struct cfq_rb_root *st;
+ unsigned group_slice;
+ enum wl_prio_t original_prio = cfqd->serving_prio;
+
+ /* Choose next priority. RT > BE > IDLE */
+ if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
+ cfqd->serving_prio = RT_WORKLOAD;
+ else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
+ cfqd->serving_prio = BE_WORKLOAD;
+ else {
+ cfqd->serving_prio = IDLE_WORKLOAD;
+ cfqd->workload_expires = jiffies + 1;
+ return;
+ }
+
+ if (original_prio != cfqd->serving_prio)
+ goto new_workload;
+
+ /*
+ * For RT and BE, we have to choose also the type
+ * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
+ * expiration time
+ */
+ st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
+ count = st->count;
+
+ /*
+ * check workload expiration, and that we still have other queues ready
+ */
+ if (count && !time_after(jiffies, cfqd->workload_expires))
+ return;
+
+new_workload:
+ /* otherwise select new workload type */
+ cfqd->serving_type =
+ cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);
+ st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
+ count = st->count;
+
+ /*
+ * the workload slice is computed as a fraction of target latency
+ * proportional to the number of queues in that workload, over
+ * all the queues in the same priority class
+ */
+ group_slice = cfq_group_slice(cfqd, cfqg);
+
+ slice = group_slice * count /
+ max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
+ cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
+
+ if (cfqd->serving_type == ASYNC_WORKLOAD) {
+ unsigned int tmp;
+
+ /*
+ * Async queues are currently system wide. Just taking
+ * proportion of queues with-in same group will lead to higher
+ * async ratio system wide as generally root group is going
+ * to have higher weight. A more accurate thing would be to
+ * calculate system wide asnc/sync ratio.
+ */
+ tmp = cfqd->cfq_target_latency *
+ cfqg_busy_async_queues(cfqd, cfqg);
+ tmp = tmp/cfqd->busy_queues;
+ slice = min_t(unsigned, slice, tmp);
+
+ /* async workload slice is scaled down according to
+ * the sync/async slice ratio. */
+ slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
+ } else
+ /* sync workload slice is at least 2 * cfq_slice_idle */
+ slice = max(slice, 2 * cfqd->cfq_slice_idle);
+
+ slice = max_t(unsigned, slice, CFQ_MIN_TT);
+ cfq_log(cfqd, "workload slice:%d", slice);
+ cfqd->workload_expires = jiffies + slice;
+}
+
+static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
+{
+ struct cfq_rb_root *st = &cfqd->grp_service_tree;
+ struct cfq_group *cfqg;
+
+ if (RB_EMPTY_ROOT(&st->rb))
+ return NULL;
+ cfqg = cfq_rb_first_group(st);
+ update_min_vdisktime(st);
+ return cfqg;
+}
+
+static void cfq_choose_cfqg(struct cfq_data *cfqd)
+{
+ struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
+
+ cfqd->serving_group = cfqg;
+
+ /* Restore the workload type data */
+ if (cfqg->saved_workload_slice) {
+ cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
+ cfqd->serving_type = cfqg->saved_workload;
+ cfqd->serving_prio = cfqg->saved_serving_prio;
+ } else
+ cfqd->workload_expires = jiffies - 1;
+
+ choose_service_tree(cfqd, cfqg);
+}
+
+/*
+ * Select a queue for service. If we have a current active queue,
+ * check whether to continue servicing it, or retrieve and set a new one.
+ */
+static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
+{
+ struct cfq_queue *cfqq, *new_cfqq = NULL;
+
+ cfqq = cfqd->active_queue;
+ if (!cfqq)
+ goto new_queue;
+
+ if (!cfqd->rq_queued)
+ return NULL;
+
+ /*
+ * We were waiting for group to get backlogged. Expire the queue
+ */
+ if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
+ goto expire;
+
+ /*
+ * The active queue has run out of time, expire it and select new.
+ */
+ if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
+ /*
+ * If slice had not expired at the completion of last request
+ * we might not have turned on wait_busy flag. Don't expire
+ * the queue yet. Allow the group to get backlogged.
+ *
+ * The very fact that we have used the slice, that means we
+ * have been idling all along on this queue and it should be
+ * ok to wait for this request to complete.
+ */
+ if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
+ && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
+ cfqq = NULL;
+ goto keep_queue;
+ } else
+ goto check_group_idle;
+ }
+
+ /*
+ * The active queue has requests and isn't expired, allow it to
+ * dispatch.
+ */
+ if (!RB_EMPTY_ROOT(&cfqq->sort_list))
+ goto keep_queue;
+
+ /*
+ * If another queue has a request waiting within our mean seek
+ * distance, let it run. The expire code will check for close
+ * cooperators and put the close queue at the front of the service
+ * tree. If possible, merge the expiring queue with the new cfqq.
+ */
+ new_cfqq = cfq_close_cooperator(cfqd, cfqq);
+ if (new_cfqq) {
+ if (!cfqq->new_cfqq)
+ cfq_setup_merge(cfqq, new_cfqq);
+ goto expire;
+ }
+
+ /*
+ * No requests pending. If the active queue still has requests in
+ * flight or is idling for a new request, allow either of these
+ * conditions to happen (or time out) before selecting a new queue.
+ */
+ if (timer_pending(&cfqd->idle_slice_timer)) {
+ cfqq = NULL;
+ goto keep_queue;
+ }
+
+ /*
+ * This is a deep seek queue, but the device is much faster than
+ * the queue can deliver, don't idle
+ **/
+ if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
+ (cfq_cfqq_slice_new(cfqq) ||
+ (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) {
+ cfq_clear_cfqq_deep(cfqq);
+ cfq_clear_cfqq_idle_window(cfqq);
+ }
+
+ if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
+ cfqq = NULL;
+ goto keep_queue;
+ }
+
+ /*
+ * If group idle is enabled and there are requests dispatched from
+ * this group, wait for requests to complete.
+ */
+check_group_idle:
+ if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 &&
+ cfqq->cfqg->dispatched &&
+ !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) {
+ cfqq = NULL;
+ goto keep_queue;
+ }
+
+expire:
+ cfq_slice_expired(cfqd, 0);
+new_queue:
+ /*
+ * Current queue expired. Check if we have to switch to a new
+ * service tree
+ */
+ if (!new_cfqq)
+ cfq_choose_cfqg(cfqd);
+
+ cfqq = cfq_set_active_queue(cfqd, new_cfqq);
+keep_queue:
+ return cfqq;
+}
+
+static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
+{
+ int dispatched = 0;
+
+ while (cfqq->next_rq) {
+ cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
+ dispatched++;
+ }
+
+ BUG_ON(!list_empty(&cfqq->fifo));
+
+ /* By default cfqq is not expired if it is empty. Do it explicitly */
+ __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
+ return dispatched;
+}
+
+/*
+ * Drain our current requests. Used for barriers and when switching
+ * io schedulers on-the-fly.
+ */
+static int cfq_forced_dispatch(struct cfq_data *cfqd)
+{
+ struct cfq_queue *cfqq;
+ int dispatched = 0;
+
+ /* Expire the timeslice of the current active queue first */
+ cfq_slice_expired(cfqd, 0);
+ while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
+ __cfq_set_active_queue(cfqd, cfqq);
+ dispatched += __cfq_forced_dispatch_cfqq(cfqq);
+ }
+
+ BUG_ON(cfqd->busy_queues);
+
+ cfq_log(cfqd, "forced_dispatch=%d", dispatched);
+ return dispatched;
+}
+
+static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
+ struct cfq_queue *cfqq)
+{
+ /* the queue hasn't finished any request, can't estimate */
+ if (cfq_cfqq_slice_new(cfqq))
+ return true;
+ if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
+ cfqq->slice_end))
+ return true;
+
+ return false;
+}
+
+static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+ unsigned int max_dispatch;
+
+ /*
+ * Drain async requests before we start sync IO
+ */
+ if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
+ return false;
+
+ /*
+ * If this is an async queue and we have sync IO in flight, let it wait
+ */
+ if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
+ return false;
+
+ max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
+ if (cfq_class_idle(cfqq))
+ max_dispatch = 1;
+
+ /*
+ * Does this cfqq already have too much IO in flight?
+ */
+ if (cfqq->dispatched >= max_dispatch) {
+ bool promote_sync = false;
+ /*
+ * idle queue must always only have a single IO in flight
+ */
+ if (cfq_class_idle(cfqq))
+ return false;
+
+ /*
+ * If there is only one sync queue
+ * we can ignore async queue here and give the sync
+ * queue no dispatch limit. The reason is a sync queue can
+ * preempt async queue, limiting the sync queue doesn't make
+ * sense. This is useful for aiostress test.
+ */
+ if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
+ promote_sync = true;
+
+ /*
+ * We have other queues, don't allow more IO from this one
+ */
+ if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
+ !promote_sync)
+ return false;
+
+ /*
+ * Sole queue user, no limit
+ */
+ if (cfqd->busy_queues == 1 || promote_sync)
+ max_dispatch = -1;
+ else
+ /*
+ * Normally we start throttling cfqq when cfq_quantum/2
+ * requests have been dispatched. But we can drive
+ * deeper queue depths at the beginning of slice
+ * subjected to upper limit of cfq_quantum.
+ * */
+ max_dispatch = cfqd->cfq_quantum;
+ }
+
+ /*
+ * Async queues must wait a bit before being allowed dispatch.
+ * We also ramp up the dispatch depth gradually for async IO,
+ * based on the last sync IO we serviced
+ */
+ if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
+ unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
+ unsigned int depth;
+
+ depth = last_sync / cfqd->cfq_slice[1];
+ if (!depth && !cfqq->dispatched)
+ depth = 1;
+ if (depth < max_dispatch)
+ max_dispatch = depth;
+ }
+
+ /*
+ * If we're below the current max, allow a dispatch
+ */
+ return cfqq->dispatched < max_dispatch;
+}
+
+/*
+ * Dispatch a request from cfqq, moving them to the request queue
+ * dispatch list.
+ */
+static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+ struct request *rq;
+
+ BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
+
+ if (!cfq_may_dispatch(cfqd, cfqq))
+ return false;
+
+ /*
+ * follow expired path, else get first next available
+ */
+ rq = cfq_check_fifo(cfqq);
+ if (!rq)
+ rq = cfqq->next_rq;
+
+ /*
+ * insert request into driver dispatch list
+ */
+ cfq_dispatch_insert(cfqd->queue, rq);
+
+ if (!cfqd->active_cic) {
+ struct cfq_io_cq *cic = RQ_CIC(rq);
+
+ atomic_long_inc(&cic->icq.ioc->refcount);
+ cfqd->active_cic = cic;
+ }
+
+ return true;
+}
+
+/*
+ * Find the cfqq that we need to service and move a request from that to the
+ * dispatch list
+ */
+static int cfq_dispatch_requests(struct request_queue *q, int force)
+{
+ struct cfq_data *cfqd = q->elevator->elevator_data;
+ struct cfq_queue *cfqq;
+
+ if (!cfqd->busy_queues)
+ return 0;
+
+ if (unlikely(force))
+ return cfq_forced_dispatch(cfqd);
+
+ cfqq = cfq_select_queue(cfqd);
+ if (!cfqq)
+ return 0;
+
+ /*
+ * Dispatch a request from this cfqq, if it is allowed
+ */
+ if (!cfq_dispatch_request(cfqd, cfqq))
+ return 0;
+
+ cfqq->slice_dispatch++;
+ cfq_clear_cfqq_must_dispatch(cfqq);
+
+ /*
+ * expire an async queue immediately if it has used up its slice. idle
+ * queue always expire after 1 dispatch round.
+ */
+ if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
+ cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
+ cfq_class_idle(cfqq))) {
+ cfqq->slice_end = jiffies + 1;
+ cfq_slice_expired(cfqd, 0);
+ }
+
+ cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
+ return 1;
+}
+
+/*
+ * task holds one reference to the queue, dropped when task exits. each rq
+ * in-flight on this queue also holds a reference, dropped when rq is freed.
+ *
+ * Each cfq queue took a reference on the parent group. Drop it now.
+ * queue lock must be held here.
+ */
+static void cfq_put_queue(struct cfq_queue *cfqq)
+{
+ struct cfq_data *cfqd = cfqq->cfqd;
+ struct cfq_group *cfqg;
+
+ BUG_ON(cfqq->ref <= 0);
+
+ cfqq->ref--;
+ if (cfqq->ref)
+ return;
+
+ cfq_log_cfqq(cfqd, cfqq, "put_queue");
+ BUG_ON(rb_first(&cfqq->sort_list));
+ BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
+ cfqg = cfqq->cfqg;
+
+ if (unlikely(cfqd->active_queue == cfqq)) {
+ __cfq_slice_expired(cfqd, cfqq, 0);
+ cfq_schedule_dispatch(cfqd);
+ }
+
+ BUG_ON(cfq_cfqq_on_rr(cfqq));
+ kmem_cache_free(cfq_pool, cfqq);
+ cfq_put_cfqg(cfqg);
+}
+
+static void cfq_put_cooperator(struct cfq_queue *cfqq)
+{
+ struct cfq_queue *__cfqq, *next;
+
+ /*
+ * If this queue was scheduled to merge with another queue, be
+ * sure to drop the reference taken on that queue (and others in
+ * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
+ */
+ __cfqq = cfqq->new_cfqq;
+ while (__cfqq) {
+ if (__cfqq == cfqq) {
+ WARN(1, "cfqq->new_cfqq loop detected\n");
+ break;
+ }
+ next = __cfqq->new_cfqq;
+ cfq_put_queue(__cfqq);
+ __cfqq = next;
+ }
+}
+
+static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+ if (unlikely(cfqq == cfqd->active_queue)) {
+ __cfq_slice_expired(cfqd, cfqq, 0);
+ cfq_schedule_dispatch(cfqd);
+ }
+
+ cfq_put_cooperator(cfqq);
+
+ cfq_put_queue(cfqq);
+}
+
+static void cfq_init_icq(struct io_cq *icq)
+{
+ struct cfq_io_cq *cic = icq_to_cic(icq);
+
+ cic->ttime.last_end_request = jiffies;
+}
+
+static void cfq_exit_icq(struct io_cq *icq)
+{
+ struct cfq_io_cq *cic = icq_to_cic(icq);
+ struct cfq_data *cfqd = cic_to_cfqd(cic);
+
+ if (cic->cfqq[BLK_RW_ASYNC]) {
+ cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
+ cic->cfqq[BLK_RW_ASYNC] = NULL;
+ }
+
+ if (cic->cfqq[BLK_RW_SYNC]) {
+ cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
+ cic->cfqq[BLK_RW_SYNC] = NULL;
+ }
+}
+
+static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
+{
+ struct task_struct *tsk = current;
+ int ioprio_class;
+
+ if (!cfq_cfqq_prio_changed(cfqq))
+ return;
+
+ ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
+ switch (ioprio_class) {
+ default:
+ printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
+ case IOPRIO_CLASS_NONE:
+ /*
+ * no prio set, inherit CPU scheduling settings
+ */
+ cfqq->ioprio = task_nice_ioprio(tsk);
+ cfqq->ioprio_class = task_nice_ioclass(tsk);
+ break;
+ case IOPRIO_CLASS_RT:
+ cfqq->ioprio = task_ioprio(ioc);
+ cfqq->ioprio_class = IOPRIO_CLASS_RT;
+ break;
+ case IOPRIO_CLASS_BE:
+ cfqq->ioprio = task_ioprio(ioc);
+ cfqq->ioprio_class = IOPRIO_CLASS_BE;
+ break;
+ case IOPRIO_CLASS_IDLE:
+ cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
+ cfqq->ioprio = 7;
+ cfq_clear_cfqq_idle_window(cfqq);
+ break;
+ }
+
+ /*
+ * keep track of original prio settings in case we have to temporarily
+ * elevate the priority of this queue
+ */
+ cfqq->org_ioprio = cfqq->ioprio;
+ cfq_clear_cfqq_prio_changed(cfqq);
+}
+
+static void changed_ioprio(struct cfq_io_cq *cic)
+{
+ struct cfq_data *cfqd = cic_to_cfqd(cic);
+ struct cfq_queue *cfqq;
+
+ if (unlikely(!cfqd))
+ return;
+
+ cfqq = cic->cfqq[BLK_RW_ASYNC];
+ if (cfqq) {
+ struct cfq_queue *new_cfqq;
+ new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->icq.ioc,
+ GFP_ATOMIC);
+ if (new_cfqq) {
+ cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
+ cfq_put_queue(cfqq);
+ }
+ }
+
+ cfqq = cic->cfqq[BLK_RW_SYNC];
+ if (cfqq)
+ cfq_mark_cfqq_prio_changed(cfqq);
+}
+
+static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
+ pid_t pid, bool is_sync)
+{
+ RB_CLEAR_NODE(&cfqq->rb_node);
+ RB_CLEAR_NODE(&cfqq->p_node);
+ INIT_LIST_HEAD(&cfqq->fifo);
+
+ cfqq->ref = 0;
+ cfqq->cfqd = cfqd;
+
+ cfq_mark_cfqq_prio_changed(cfqq);
+
+ if (is_sync) {
+ if (!cfq_class_idle(cfqq))
+ cfq_mark_cfqq_idle_window(cfqq);
+ cfq_mark_cfqq_sync(cfqq);
+ }
+ cfqq->pid = pid;
+}
+
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+static void changed_cgroup(struct cfq_io_cq *cic)
+{
+ struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1);
+ struct cfq_data *cfqd = cic_to_cfqd(cic);
+ struct request_queue *q;
+
+ if (unlikely(!cfqd))
+ return;
+
+ q = cfqd->queue;
+
+ if (sync_cfqq) {
+ /*
+ * Drop reference to sync queue. A new sync queue will be
+ * assigned in new group upon arrival of a fresh request.
+ */
+ cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
+ cic_set_cfqq(cic, NULL, 1);
+ cfq_put_queue(sync_cfqq);
+ }
+}
+#endif /* CONFIG_CFQ_GROUP_IOSCHED */
+
+static struct cfq_queue *
+cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
+ struct io_context *ioc, gfp_t gfp_mask)
+{
+ struct cfq_queue *cfqq, *new_cfqq = NULL;
+ struct cfq_io_cq *cic;
+ struct cfq_group *cfqg;
+
+retry:
+ cfqg = cfq_get_cfqg(cfqd);
+ cic = cfq_cic_lookup(cfqd, ioc);
+ /* cic always exists here */
+ cfqq = cic_to_cfqq(cic, is_sync);
+
+ /*
+ * Always try a new alloc if we fell back to the OOM cfqq
+ * originally, since it should just be a temporary situation.
+ */
+ if (!cfqq || cfqq == &cfqd->oom_cfqq) {
+ cfqq = NULL;
+ if (new_cfqq) {
+ cfqq = new_cfqq;
+ new_cfqq = NULL;
+ } else if (gfp_mask & __GFP_WAIT) {
+ spin_unlock_irq(cfqd->queue->queue_lock);
+ new_cfqq = kmem_cache_alloc_node(cfq_pool,
+ gfp_mask | __GFP_ZERO,
+ cfqd->queue->node);
+ spin_lock_irq(cfqd->queue->queue_lock);
+ if (new_cfqq)
+ goto retry;
+ } else {
+ cfqq = kmem_cache_alloc_node(cfq_pool,
+ gfp_mask | __GFP_ZERO,
+ cfqd->queue->node);
+ }
+
+ if (cfqq) {
+ cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
+ cfq_init_prio_data(cfqq, ioc);
+ cfq_link_cfqq_cfqg(cfqq, cfqg);
+ cfq_log_cfqq(cfqd, cfqq, "alloced");
+ } else
+ cfqq = &cfqd->oom_cfqq;
+ }
+
+ if (new_cfqq)
+ kmem_cache_free(cfq_pool, new_cfqq);
+
+ return cfqq;
+}
+
+static struct cfq_queue **
+cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
+{
+ switch (ioprio_class) {
+ case IOPRIO_CLASS_RT:
+ return &cfqd->async_cfqq[0][ioprio];
+ case IOPRIO_CLASS_BE:
+ return &cfqd->async_cfqq[1][ioprio];
+ case IOPRIO_CLASS_IDLE:
+ return &cfqd->async_idle_cfqq;
+ default:
+ BUG();
+ }
+}
+
+static struct cfq_queue *
+cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
+ gfp_t gfp_mask)
+{
+ const int ioprio = task_ioprio(ioc);
+ const int ioprio_class = task_ioprio_class(ioc);
+ struct cfq_queue **async_cfqq = NULL;
+ struct cfq_queue *cfqq = NULL;
+
+ if (!is_sync) {
+ async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
+ cfqq = *async_cfqq;
+ }
+
+ if (!cfqq)
+ cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
+
+ /*
+ * pin the queue now that it's allocated, scheduler exit will prune it
+ */
+ if (!is_sync && !(*async_cfqq)) {
+ cfqq->ref++;
+ *async_cfqq = cfqq;
+ }
+
+ cfqq->ref++;
+ return cfqq;
+}
+
+static void
+__cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle)
+{
+ unsigned long elapsed = jiffies - ttime->last_end_request;
+ elapsed = min(elapsed, 2UL * slice_idle);
+
+ ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
+ ttime->ttime_total = (7*ttime->ttime_total + 256*elapsed) / 8;
+ ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples;
+}
+
+static void
+cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
+ struct cfq_io_cq *cic)
+{
+ if (cfq_cfqq_sync(cfqq)) {
+ __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
+ __cfq_update_io_thinktime(&cfqq->service_tree->ttime,
+ cfqd->cfq_slice_idle);
+ }
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+ __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle);
+#endif
+}
+
+static void
+cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
+ struct request *rq)
+{
+ sector_t sdist = 0;
+ sector_t n_sec = blk_rq_sectors(rq);
+ if (cfqq->last_request_pos) {
+ if (cfqq->last_request_pos < blk_rq_pos(rq))
+ sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
+ else
+ sdist = cfqq->last_request_pos - blk_rq_pos(rq);
+ }
+
+ cfqq->seek_history <<= 1;
+ if (blk_queue_nonrot(cfqd->queue))
+ cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
+ else
+ cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
+}
+
+/*
+ * Disable idle window if the process thinks too long or seeks so much that
+ * it doesn't matter
+ */
+static void
+cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
+ struct cfq_io_cq *cic)
+{
+ int old_idle, enable_idle;
+
+ /*
+ * Don't idle for async or idle io prio class
+ */
+ if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
+ return;
+
+ enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
+
+ if (cfqq->queued[0] + cfqq->queued[1] >= 4)
+ cfq_mark_cfqq_deep(cfqq);
+
+ if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
+ enable_idle = 0;
+ else if (!atomic_read(&cic->icq.ioc->nr_tasks) ||
+ !cfqd->cfq_slice_idle ||
+ (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
+ enable_idle = 0;
+ else if (sample_valid(cic->ttime.ttime_samples)) {
+ if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
+ enable_idle = 0;
+ else
+ enable_idle = 1;
+ }
+
+ if (old_idle != enable_idle) {
+ cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
+ if (enable_idle)
+ cfq_mark_cfqq_idle_window(cfqq);
+ else
+ cfq_clear_cfqq_idle_window(cfqq);
+ }
+}
+
+/*
+ * Check if new_cfqq should preempt the currently active queue. Return 0 for
+ * no or if we aren't sure, a 1 will cause a preempt.
+ */
+static bool
+cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
+ struct request *rq)
+{
+ struct cfq_queue *cfqq;
+
+ cfqq = cfqd->active_queue;
+ if (!cfqq)
+ return false;
+
+ if (cfq_class_idle(new_cfqq))
+ return false;
+
+ if (cfq_class_idle(cfqq))
+ return true;
+
+ /*
+ * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
+ */
+ if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
+ return false;
+
+ /*
+ * if the new request is sync, but the currently running queue is
+ * not, let the sync request have priority.
+ */
+ if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
+ return true;
+
+ if (new_cfqq->cfqg != cfqq->cfqg)
+ return false;
+
+ if (cfq_slice_used(cfqq))
+ return true;
+
+ /* Allow preemption only if we are idling on sync-noidle tree */
+ if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
+ cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
+ new_cfqq->service_tree->count == 2 &&
+ RB_EMPTY_ROOT(&cfqq->sort_list))
+ return true;
+
+ /*
+ * So both queues are sync. Let the new request get disk time if
+ * it's a metadata request and the current queue is doing regular IO.
+ */
+ if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending)
+ return true;
+
+ /*
+ * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
+ */
+ if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
+ return true;
+
+ /* An idle queue should not be idle now for some reason */
+ if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
+ return true;
+
+ if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
+ return false;
+
+ /*
+ * if this request is as-good as one we would expect from the
+ * current cfqq, let it preempt
+ */
+ if (cfq_rq_close(cfqd, cfqq, rq))
+ return true;
+
+ return false;
+}
+
+/*
+ * cfqq preempts the active queue. if we allowed preempt with no slice left,
+ * let it have half of its nominal slice.
+ */
+static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+ enum wl_type_t old_type = cfqq_type(cfqd->active_queue);
+
+ cfq_log_cfqq(cfqd, cfqq, "preempt");
+ cfq_slice_expired(cfqd, 1);
+
+ /*
+ * workload type is changed, don't save slice, otherwise preempt
+ * doesn't happen
+ */
+ if (old_type != cfqq_type(cfqq))
+ cfqq->cfqg->saved_workload_slice = 0;
+
+ /*
+ * Put the new queue at the front of the of the current list,
+ * so we know that it will be selected next.
+ */
+ BUG_ON(!cfq_cfqq_on_rr(cfqq));
+
+ cfq_service_tree_add(cfqd, cfqq, 1);
+
+ cfqq->slice_end = 0;
+ cfq_mark_cfqq_slice_new(cfqq);
+}
+
+/*
+ * Called when a new fs request (rq) is added (to cfqq). Check if there's
+ * something we should do about it
+ */
+static void
+cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
+ struct request *rq)
+{
+ struct cfq_io_cq *cic = RQ_CIC(rq);
+
+ cfqd->rq_queued++;
+ if (rq->cmd_flags & REQ_PRIO)
+ cfqq->prio_pending++;
+
+ cfq_update_io_thinktime(cfqd, cfqq, cic);
+ cfq_update_io_seektime(cfqd, cfqq, rq);
+ cfq_update_idle_window(cfqd, cfqq, cic);
+
+ cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
+
+ if (cfqq == cfqd->active_queue) {
+ /*
+ * Remember that we saw a request from this process, but
+ * don't start queuing just yet. Otherwise we risk seeing lots
+ * of tiny requests, because we disrupt the normal plugging
+ * and merging. If the request is already larger than a single
+ * page, let it rip immediately. For that case we assume that
+ * merging is already done. Ditto for a busy system that
+ * has other work pending, don't risk delaying until the
+ * idle timer unplug to continue working.
+ */
+ if (cfq_cfqq_wait_request(cfqq)) {
+ if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
+ cfqd->busy_queues > 1) {
+ cfq_del_timer(cfqd, cfqq);
+ cfq_clear_cfqq_wait_request(cfqq);
+ __blk_run_queue(cfqd->queue);
+ } else {
+ cfq_blkiocg_update_idle_time_stats(
+ &cfqq->cfqg->blkg);
+ cfq_mark_cfqq_must_dispatch(cfqq);
+ }
+ }
+ } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
+ /*
+ * not the active queue - expire current slice if it is
+ * idle and has expired it's mean thinktime or this new queue
+ * has some old slice time left and is of higher priority or
+ * this new queue is RT and the current one is BE
+ */
+ cfq_preempt_queue(cfqd, cfqq);
+ __blk_run_queue(cfqd->queue);
+ }
+}
+
+static void cfq_insert_request(struct request_queue *q, struct request *rq)
+{
+ struct cfq_data *cfqd = q->elevator->elevator_data;
+ struct cfq_queue *cfqq = RQ_CFQQ(rq);
+
+ cfq_log_cfqq(cfqd, cfqq, "insert_request");
+ cfq_init_prio_data(cfqq, RQ_CIC(rq)->icq.ioc);
+
+ rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
+ list_add_tail(&rq->queuelist, &cfqq->fifo);
+ cfq_add_rq_rb(rq);
+ cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
+ &cfqd->serving_group->blkg, rq_data_dir(rq),
+ rq_is_sync(rq));
+ cfq_rq_enqueued(cfqd, cfqq, rq);
+}
+
+/*
+ * Update hw_tag based on peak queue depth over 50 samples under
+ * sufficient load.
+ */
+static void cfq_update_hw_tag(struct cfq_data *cfqd)
+{
+ struct cfq_queue *cfqq = cfqd->active_queue;
+
+ if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
+ cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
+
+ if (cfqd->hw_tag == 1)
+ return;
+
+ if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
+ cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
+ return;
+
+ /*
+ * If active queue hasn't enough requests and can idle, cfq might not
+ * dispatch sufficient requests to hardware. Don't zero hw_tag in this
+ * case
+ */
+ if (cfqq && cfq_cfqq_idle_window(cfqq) &&
+ cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
+ CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
+ return;
+
+ if (cfqd->hw_tag_samples++ < 50)
+ return;
+
+ if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
+ cfqd->hw_tag = 1;
+ else
+ cfqd->hw_tag = 0;
+}
+
+static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+ struct cfq_io_cq *cic = cfqd->active_cic;
+
+ /* If the queue already has requests, don't wait */
+ if (!RB_EMPTY_ROOT(&cfqq->sort_list))
+ return false;
+
+ /* If there are other queues in the group, don't wait */
+ if (cfqq->cfqg->nr_cfqq > 1)
+ return false;
+
+ /* the only queue in the group, but think time is big */
+ if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true))
+ return false;
+
+ if (cfq_slice_used(cfqq))
+ return true;
+
+ /* if slice left is less than think time, wait busy */
+ if (cic && sample_valid(cic->ttime.ttime_samples)
+ && (cfqq->slice_end - jiffies < cic->ttime.ttime_mean))
+ return true;
+
+ /*
+ * If think times is less than a jiffy than ttime_mean=0 and above
+ * will not be true. It might happen that slice has not expired yet
+ * but will expire soon (4-5 ns) during select_queue(). To cover the
+ * case where think time is less than a jiffy, mark the queue wait
+ * busy if only 1 jiffy is left in the slice.
+ */
+ if (cfqq->slice_end - jiffies == 1)
+ return true;
+
+ return false;
+}
+
+static void cfq_completed_request(struct request_queue *q, struct request *rq)
+{
+ struct cfq_queue *cfqq = RQ_CFQQ(rq);
+ struct cfq_data *cfqd = cfqq->cfqd;
+ const int sync = rq_is_sync(rq);
+ unsigned long now;
+
+ now = jiffies;
+ cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
+ !!(rq->cmd_flags & REQ_NOIDLE));
+
+ cfq_update_hw_tag(cfqd);
+
+ WARN_ON(!cfqd->rq_in_driver);
+ WARN_ON(!cfqq->dispatched);
+ cfqd->rq_in_driver--;
+ cfqq->dispatched--;
+ (RQ_CFQG(rq))->dispatched--;
+ cfq_blkiocg_update_completion_stats(&cfqq->cfqg->blkg,
+ rq_start_time_ns(rq), rq_io_start_time_ns(rq),
+ rq_data_dir(rq), rq_is_sync(rq));
+
+ cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
+
+ if (sync) {
+ struct cfq_rb_root *service_tree;
+
+ RQ_CIC(rq)->ttime.last_end_request = now;
+
+ if (cfq_cfqq_on_rr(cfqq))
+ service_tree = cfqq->service_tree;
+ else
+ service_tree = service_tree_for(cfqq->cfqg,
+ cfqq_prio(cfqq), cfqq_type(cfqq));
+ service_tree->ttime.last_end_request = now;
+ if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
+ cfqd->last_delayed_sync = now;
+ }
+
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+ cfqq->cfqg->ttime.last_end_request = now;
+#endif
+
+ /*
+ * If this is the active queue, check if it needs to be expired,
+ * or if we want to idle in case it has no pending requests.
+ */
+ if (cfqd->active_queue == cfqq) {
+ const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
+
+ if (cfq_cfqq_slice_new(cfqq)) {
+ cfq_set_prio_slice(cfqd, cfqq);
+ cfq_clear_cfqq_slice_new(cfqq);
+ }
+
+ /*
+ * Should we wait for next request to come in before we expire
+ * the queue.
+ */
+ if (cfq_should_wait_busy(cfqd, cfqq)) {
+ unsigned long extend_sl = cfqd->cfq_slice_idle;
+ if (!cfqd->cfq_slice_idle)
+ extend_sl = cfqd->cfq_group_idle;
+ cfqq->slice_end = jiffies + extend_sl;
+ cfq_mark_cfqq_wait_busy(cfqq);
+ cfq_log_cfqq(cfqd, cfqq, "will busy wait");
+ }
+
+ /*
+ * Idling is not enabled on:
+ * - expired queues
+ * - idle-priority queues
+ * - async queues
+ * - queues with still some requests queued
+ * - when there is a close cooperator
+ */
+ if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
+ cfq_slice_expired(cfqd, 1);
+ else if (sync && cfqq_empty &&
+ !cfq_close_cooperator(cfqd, cfqq)) {
+ cfq_arm_slice_timer(cfqd);
+ }
+ }
+
+ if (!cfqd->rq_in_driver)
+ cfq_schedule_dispatch(cfqd);
+}
+
+static inline int __cfq_may_queue(struct cfq_queue *cfqq)
+{
+ if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
+ cfq_mark_cfqq_must_alloc_slice(cfqq);
+ return ELV_MQUEUE_MUST;
+ }
+
+ return ELV_MQUEUE_MAY;
+}
+
+static int cfq_may_queue(struct request_queue *q, int rw)
+{
+ struct cfq_data *cfqd = q->elevator->elevator_data;
+ struct task_struct *tsk = current;
+ struct cfq_io_cq *cic;
+ struct cfq_queue *cfqq;
+
+ /*
+ * don't force setup of a queue from here, as a call to may_queue
+ * does not necessarily imply that a request actually will be queued.
+ * so just lookup a possibly existing queue, or return 'may queue'
+ * if that fails
+ */
+ cic = cfq_cic_lookup(cfqd, tsk->io_context);
+ if (!cic)
+ return ELV_MQUEUE_MAY;
+
+ cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
+ if (cfqq) {
+ cfq_init_prio_data(cfqq, cic->icq.ioc);
+
+ return __cfq_may_queue(cfqq);
+ }
+
+ return ELV_MQUEUE_MAY;
+}
+
+/*
+ * queue lock held here
+ */
+static void cfq_put_request(struct request *rq)
+{
+ struct cfq_queue *cfqq = RQ_CFQQ(rq);
+
+ if (cfqq) {
+ const int rw = rq_data_dir(rq);
+
+ BUG_ON(!cfqq->allocated[rw]);
+ cfqq->allocated[rw]--;
+
+ /* Put down rq reference on cfqg */
+ cfq_put_cfqg(RQ_CFQG(rq));
+ rq->elv.priv[0] = NULL;
+ rq->elv.priv[1] = NULL;
+
+ cfq_put_queue(cfqq);
+ }
+}
+
+static struct cfq_queue *
+cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_cq *cic,
+ struct cfq_queue *cfqq)
+{
+ cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
+ cic_set_cfqq(cic, cfqq->new_cfqq, 1);
+ cfq_mark_cfqq_coop(cfqq->new_cfqq);
+ cfq_put_queue(cfqq);
+ return cic_to_cfqq(cic, 1);
+}
+
+/*
+ * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
+ * was the last process referring to said cfqq.
+ */
+static struct cfq_queue *
+split_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq)
+{
+ if (cfqq_process_refs(cfqq) == 1) {
+ cfqq->pid = current->pid;
+ cfq_clear_cfqq_coop(cfqq);
+ cfq_clear_cfqq_split_coop(cfqq);
+ return cfqq;
+ }
+
+ cic_set_cfqq(cic, NULL, 1);
+
+ cfq_put_cooperator(cfqq);
+
+ cfq_put_queue(cfqq);
+ return NULL;
+}
+/*
+ * Allocate cfq data structures associated with this request.
+ */
+static int
+cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
+{
+ struct cfq_data *cfqd = q->elevator->elevator_data;
+ struct cfq_io_cq *cic = icq_to_cic(rq->elv.icq);
+ const int rw = rq_data_dir(rq);
+ const bool is_sync = rq_is_sync(rq);
+ struct cfq_queue *cfqq;
+ unsigned int changed;
+
+ might_sleep_if(gfp_mask & __GFP_WAIT);
+
+ spin_lock_irq(q->queue_lock);
+
+ /* handle changed notifications */
+ changed = icq_get_changed(&cic->icq);
+ if (unlikely(changed & ICQ_IOPRIO_CHANGED))
+ changed_ioprio(cic);
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+ if (unlikely(changed & ICQ_CGROUP_CHANGED))
+ changed_cgroup(cic);
+#endif
+
+new_queue:
+ cfqq = cic_to_cfqq(cic, is_sync);
+ if (!cfqq || cfqq == &cfqd->oom_cfqq) {
+ cfqq = cfq_get_queue(cfqd, is_sync, cic->icq.ioc, gfp_mask);
+ cic_set_cfqq(cic, cfqq, is_sync);
+ } else {
+ /*
+ * If the queue was seeky for too long, break it apart.
+ */
+ if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
+ cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
+ cfqq = split_cfqq(cic, cfqq);
+ if (!cfqq)
+ goto new_queue;
+ }
+
+ /*
+ * Check to see if this queue is scheduled to merge with
+ * another, closely cooperating queue. The merging of
+ * queues happens here as it must be done in process context.
+ * The reference on new_cfqq was taken in merge_cfqqs.
+ */
+ if (cfqq->new_cfqq)
+ cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
+ }
+
+ cfqq->allocated[rw]++;
+
+ cfqq->ref++;
+ rq->elv.priv[0] = cfqq;
+ rq->elv.priv[1] = cfq_ref_get_cfqg(cfqq->cfqg);
+ spin_unlock_irq(q->queue_lock);
+ return 0;
+}
+
+static void cfq_kick_queue(struct work_struct *work)
+{
+ struct cfq_data *cfqd =
+ container_of(work, struct cfq_data, unplug_work);
+ struct request_queue *q = cfqd->queue;
+
+ spin_lock_irq(q->queue_lock);
+ __blk_run_queue(cfqd->queue);
+ spin_unlock_irq(q->queue_lock);
+}
+
+/*
+ * Timer running if the active_queue is currently idling inside its time slice
+ */
+static void cfq_idle_slice_timer(unsigned long data)
+{
+ struct cfq_data *cfqd = (struct cfq_data *) data;
+ struct cfq_queue *cfqq;
+ unsigned long flags;
+ int timed_out = 1;
+
+ cfq_log(cfqd, "idle timer fired");
+
+ spin_lock_irqsave(cfqd->queue->queue_lock, flags);
+
+ cfqq = cfqd->active_queue;
+ if (cfqq) {
+ timed_out = 0;
+
+ /*
+ * We saw a request before the queue expired, let it through
+ */
+ if (cfq_cfqq_must_dispatch(cfqq))
+ goto out_kick;
+
+ /*
+ * expired
+ */
+ if (cfq_slice_used(cfqq))
+ goto expire;
+
+ /*
+ * only expire and reinvoke request handler, if there are
+ * other queues with pending requests
+ */
+ if (!cfqd->busy_queues)
+ goto out_cont;
+
+ /*
+ * not expired and it has a request pending, let it dispatch
+ */
+ if (!RB_EMPTY_ROOT(&cfqq->sort_list))
+ goto out_kick;
+
+ /*
+ * Queue depth flag is reset only when the idle didn't succeed
+ */
+ cfq_clear_cfqq_deep(cfqq);
+ }
+expire:
+ cfq_slice_expired(cfqd, timed_out);
+out_kick:
+ cfq_schedule_dispatch(cfqd);
+out_cont:
+ spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
+}
+
+static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
+{
+ del_timer_sync(&cfqd->idle_slice_timer);
+ cancel_work_sync(&cfqd->unplug_work);
+}
+
+static void cfq_put_async_queues(struct cfq_data *cfqd)
+{
+ int i;
+
+ for (i = 0; i < IOPRIO_BE_NR; i++) {
+ if (cfqd->async_cfqq[0][i])
+ cfq_put_queue(cfqd->async_cfqq[0][i]);
+ if (cfqd->async_cfqq[1][i])
+ cfq_put_queue(cfqd->async_cfqq[1][i]);
+ }
+
+ if (cfqd->async_idle_cfqq)
+ cfq_put_queue(cfqd->async_idle_cfqq);
+}
+
+static void cfq_exit_queue(struct elevator_queue *e)
+{
+ struct cfq_data *cfqd = e->elevator_data;
+ struct request_queue *q = cfqd->queue;
+ bool wait = false;
+
+ cfq_shutdown_timer_wq(cfqd);
+
+ spin_lock_irq(q->queue_lock);
+
+ if (cfqd->active_queue)
+ __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
+
+ cfq_put_async_queues(cfqd);
+ cfq_release_cfq_groups(cfqd);
+
+ /*
+ * If there are groups which we could not unlink from blkcg list,
+ * wait for a rcu period for them to be freed.
+ */
+ if (cfqd->nr_blkcg_linked_grps)
+ wait = true;
+
+ spin_unlock_irq(q->queue_lock);
+
+ cfq_shutdown_timer_wq(cfqd);
+
+ /*
+ * Wait for cfqg->blkg->key accessors to exit their grace periods.
+ * Do this wait only if there are other unlinked groups out
+ * there. This can happen if cgroup deletion path claimed the
+ * responsibility of cleaning up a group before queue cleanup code
+ * get to the group.
+ *
+ * Do not call synchronize_rcu() unconditionally as there are drivers
+ * which create/delete request queue hundreds of times during scan/boot
+ * and synchronize_rcu() can take significant time and slow down boot.
+ */
+ if (wait)
+ synchronize_rcu();
+
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+ /* Free up per cpu stats for root group */
+ free_percpu(cfqd->root_group.blkg.stats_cpu);
+#endif
+ kfree(cfqd);
+}
+
+static void *cfq_init_queue(struct request_queue *q)
+{
+ struct cfq_data *cfqd;
+ int i, j;
+ struct cfq_group *cfqg;
+ struct cfq_rb_root *st;
+
+ cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
+ if (!cfqd)
+ return NULL;
+
+ /* Init root service tree */
+ cfqd->grp_service_tree = CFQ_RB_ROOT;
+
+ /* Init root group */
+ cfqg = &cfqd->root_group;
+ for_each_cfqg_st(cfqg, i, j, st)
+ *st = CFQ_RB_ROOT;
+ RB_CLEAR_NODE(&cfqg->rb_node);
+
+ /* Give preference to root group over other groups */
+ cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;
+
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+ /*
+ * Set root group reference to 2. One reference will be dropped when
+ * all groups on cfqd->cfqg_list are being deleted during queue exit.
+ * Other reference will remain there as we don't want to delete this
+ * group as it is statically allocated and gets destroyed when
+ * throtl_data goes away.
+ */
+ cfqg->ref = 2;
+
+ if (blkio_alloc_blkg_stats(&cfqg->blkg)) {
+ kfree(cfqg);
+ kfree(cfqd);
+ return NULL;
+ }
+
+ rcu_read_lock();
+
+ cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg,
+ (void *)cfqd, 0);
+ rcu_read_unlock();
+ cfqd->nr_blkcg_linked_grps++;
+
+ /* Add group on cfqd->cfqg_list */
+ hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
+#endif
+ /*
+ * Not strictly needed (since RB_ROOT just clears the node and we
+ * zeroed cfqd on alloc), but better be safe in case someone decides
+ * to add magic to the rb code
+ */
+ for (i = 0; i < CFQ_PRIO_LISTS; i++)
+ cfqd->prio_trees[i] = RB_ROOT;
+
+ /*
+ * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
+ * Grab a permanent reference to it, so that the normal code flow
+ * will not attempt to free it.
+ */
+ cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
+ cfqd->oom_cfqq.ref++;
+ cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);
+
+ cfqd->queue = q;
+
+ init_timer(&cfqd->idle_slice_timer);
+ cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
+ cfqd->idle_slice_timer.data = (unsigned long) cfqd;
+
+ INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
+
+ cfqd->cfq_quantum = cfq_quantum;
+ cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
+ cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
+ cfqd->cfq_back_max = cfq_back_max;
+ cfqd->cfq_back_penalty = cfq_back_penalty;
+ cfqd->cfq_slice[0] = cfq_slice_async;
+ cfqd->cfq_slice[1] = cfq_slice_sync;
+ cfqd->cfq_target_latency = cfq_target_latency;
+ cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
+ cfqd->cfq_slice_idle = cfq_slice_idle;
+ cfqd->cfq_group_idle = cfq_group_idle;
+ cfqd->cfq_latency = 1;
+ cfqd->hw_tag = -1;
+ /*
+ * we optimistically start assuming sync ops weren't delayed in last
+ * second, in order to have larger depth for async operations.
+ */
+ cfqd->last_delayed_sync = jiffies - HZ;
+ return cfqd;
+}
+
+/*
+ * sysfs parts below -->
+ */
+static ssize_t
+cfq_var_show(unsigned int var, char *page)
+{
+ return sprintf(page, "%d\n", var);
+}
+
+static ssize_t
+cfq_var_store(unsigned int *var, const char *page, size_t count)
+{
+ char *p = (char *) page;
+
+ *var = simple_strtoul(p, &p, 10);
+ return count;
+}
+
+#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
+static ssize_t __FUNC(struct elevator_queue *e, char *page) \
+{ \
+ struct cfq_data *cfqd = e->elevator_data; \
+ unsigned int __data = __VAR; \
+ if (__CONV) \
+ __data = jiffies_to_msecs(__data); \
+ return cfq_var_show(__data, (page)); \
+}
+SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
+SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
+SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
+SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
+SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
+SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
+SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
+SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
+SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
+SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
+SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
+SHOW_FUNCTION(cfq_target_latency_show, cfqd->cfq_target_latency, 1);
+#undef SHOW_FUNCTION
+
+#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
+static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
+{ \
+ struct cfq_data *cfqd = e->elevator_data; \
+ unsigned int __data; \
+ int ret = cfq_var_store(&__data, (page), count); \
+ if (__data < (MIN)) \
+ __data = (MIN); \
+ else if (__data > (MAX)) \
+ __data = (MAX); \
+ if (__CONV) \
+ *(__PTR) = msecs_to_jiffies(__data); \
+ else \
+ *(__PTR) = __data; \
+ return ret; \
+}
+STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
+STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
+ UINT_MAX, 1);
+STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
+ UINT_MAX, 1);
+STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
+STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
+ UINT_MAX, 0);
+STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
+STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
+STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
+STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
+STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
+ UINT_MAX, 0);
+STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
+STORE_FUNCTION(cfq_target_latency_store, &cfqd->cfq_target_latency, 1, UINT_MAX, 1);
+#undef STORE_FUNCTION
+
+#define CFQ_ATTR(name) \
+ __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
+
+static struct elv_fs_entry cfq_attrs[] = {
+ CFQ_ATTR(quantum),
+ CFQ_ATTR(fifo_expire_sync),
+ CFQ_ATTR(fifo_expire_async),
+ CFQ_ATTR(back_seek_max),
+ CFQ_ATTR(back_seek_penalty),
+ CFQ_ATTR(slice_sync),
+ CFQ_ATTR(slice_async),
+ CFQ_ATTR(slice_async_rq),
+ CFQ_ATTR(slice_idle),
+ CFQ_ATTR(group_idle),
+ CFQ_ATTR(low_latency),
+ CFQ_ATTR(target_latency),
+ __ATTR_NULL
+};
+
+static struct elevator_type iosched_cfq = {
+ .ops = {
+ .elevator_merge_fn = cfq_merge,
+ .elevator_merged_fn = cfq_merged_request,
+ .elevator_merge_req_fn = cfq_merged_requests,
+ .elevator_allow_merge_fn = cfq_allow_merge,
+ .elevator_bio_merged_fn = cfq_bio_merged,
+ .elevator_dispatch_fn = cfq_dispatch_requests,
+ .elevator_add_req_fn = cfq_insert_request,
+ .elevator_activate_req_fn = cfq_activate_request,
+ .elevator_deactivate_req_fn = cfq_deactivate_request,
+ .elevator_completed_req_fn = cfq_completed_request,
+ .elevator_former_req_fn = elv_rb_former_request,
+ .elevator_latter_req_fn = elv_rb_latter_request,
+ .elevator_init_icq_fn = cfq_init_icq,
+ .elevator_exit_icq_fn = cfq_exit_icq,
+ .elevator_set_req_fn = cfq_set_request,
+ .elevator_put_req_fn = cfq_put_request,
+ .elevator_may_queue_fn = cfq_may_queue,
+ .elevator_init_fn = cfq_init_queue,
+ .elevator_exit_fn = cfq_exit_queue,
+ },
+ .icq_size = sizeof(struct cfq_io_cq),
+ .icq_align = __alignof__(struct cfq_io_cq),
+ .elevator_attrs = cfq_attrs,
+ .elevator_name = "cfq",
+ .elevator_owner = THIS_MODULE,
+};
+
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+static struct blkio_policy_type blkio_policy_cfq = {
+ .ops = {
+ .blkio_unlink_group_fn = cfq_unlink_blkio_group,
+ .blkio_update_group_weight_fn = cfq_update_blkio_group_weight,
+ },
+ .plid = BLKIO_POLICY_PROP,
+};
+#else
+static struct blkio_policy_type blkio_policy_cfq;
+#endif
+
+static int __init cfq_init(void)
+{
+ int ret;
+
+ /*
+ * could be 0 on HZ < 1000 setups
+ */
+ if (!cfq_slice_async)
+ cfq_slice_async = 1;
+ if (!cfq_slice_idle)
+ cfq_slice_idle = 1;
+
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+ if (!cfq_group_idle)
+ cfq_group_idle = 1;
+#else
+ cfq_group_idle = 0;
+#endif
+ cfq_pool = KMEM_CACHE(cfq_queue, 0);
+ if (!cfq_pool)
+ return -ENOMEM;
+
+ ret = elv_register(&iosched_cfq);
+ if (ret) {
+ kmem_cache_destroy(cfq_pool);
+ return ret;
+ }
+
+ blkio_policy_register(&blkio_policy_cfq);
+
+ return 0;
+}
+
+static void __exit cfq_exit(void)
+{
+ blkio_policy_unregister(&blkio_policy_cfq);
+ elv_unregister(&iosched_cfq);
+ kmem_cache_destroy(cfq_pool);
+}
+
+module_init(cfq_init);
+module_exit(cfq_exit);
+
+MODULE_AUTHOR("Jens Axboe");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");