![Christoph Hellwig](/assets/img/avatar_default.png)
Switch these constants to an enum, and make let the compiler ensure that all callers of blk_try_merge and elv_merge handle all potential values. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
1165 lines
27 KiB
C
1165 lines
27 KiB
C
/*
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* Block device elevator/IO-scheduler.
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*
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* Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
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*
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* 30042000 Jens Axboe <axboe@kernel.dk> :
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*
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* Split the elevator a bit so that it is possible to choose a different
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* one or even write a new "plug in". There are three pieces:
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* - elevator_fn, inserts a new request in the queue list
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* - elevator_merge_fn, decides whether a new buffer can be merged with
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* an existing request
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* - elevator_dequeue_fn, called when a request is taken off the active list
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*
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* 20082000 Dave Jones <davej@suse.de> :
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* Removed tests for max-bomb-segments, which was breaking elvtune
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* when run without -bN
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*
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* Jens:
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* - Rework again to work with bio instead of buffer_heads
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* - loose bi_dev comparisons, partition handling is right now
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* - completely modularize elevator setup and teardown
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*
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*/
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#include <linux/kernel.h>
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#include <linux/fs.h>
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#include <linux/blkdev.h>
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#include <linux/elevator.h>
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#include <linux/bio.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/compiler.h>
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#include <linux/blktrace_api.h>
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#include <linux/hash.h>
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#include <linux/uaccess.h>
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#include <linux/pm_runtime.h>
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#include <linux/blk-cgroup.h>
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#include <trace/events/block.h>
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#include "blk.h"
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#include "blk-mq-sched.h"
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static DEFINE_SPINLOCK(elv_list_lock);
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static LIST_HEAD(elv_list);
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/*
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* Merge hash stuff.
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*/
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#define rq_hash_key(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
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/*
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* Query io scheduler to see if the current process issuing bio may be
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* merged with rq.
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*/
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static int elv_iosched_allow_bio_merge(struct request *rq, struct bio *bio)
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{
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struct request_queue *q = rq->q;
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struct elevator_queue *e = q->elevator;
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if (e->uses_mq && e->type->ops.mq.allow_merge)
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return e->type->ops.mq.allow_merge(q, rq, bio);
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else if (!e->uses_mq && e->type->ops.sq.elevator_allow_bio_merge_fn)
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return e->type->ops.sq.elevator_allow_bio_merge_fn(q, rq, bio);
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return 1;
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}
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/*
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* can we safely merge with this request?
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*/
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bool elv_bio_merge_ok(struct request *rq, struct bio *bio)
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{
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if (!blk_rq_merge_ok(rq, bio))
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return false;
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if (!elv_iosched_allow_bio_merge(rq, bio))
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return false;
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return true;
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}
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EXPORT_SYMBOL(elv_bio_merge_ok);
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static struct elevator_type *elevator_find(const char *name)
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{
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struct elevator_type *e;
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list_for_each_entry(e, &elv_list, list) {
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if (!strcmp(e->elevator_name, name))
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return e;
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}
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return NULL;
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}
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static void elevator_put(struct elevator_type *e)
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{
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module_put(e->elevator_owner);
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}
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static struct elevator_type *elevator_get(const char *name, bool try_loading)
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{
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struct elevator_type *e;
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spin_lock(&elv_list_lock);
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e = elevator_find(name);
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if (!e && try_loading) {
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spin_unlock(&elv_list_lock);
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request_module("%s-iosched", name);
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spin_lock(&elv_list_lock);
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e = elevator_find(name);
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}
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if (e && !try_module_get(e->elevator_owner))
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e = NULL;
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spin_unlock(&elv_list_lock);
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return e;
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}
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static char chosen_elevator[ELV_NAME_MAX];
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static int __init elevator_setup(char *str)
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{
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/*
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* Be backwards-compatible with previous kernels, so users
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* won't get the wrong elevator.
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*/
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strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1);
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return 1;
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}
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__setup("elevator=", elevator_setup);
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/* called during boot to load the elevator chosen by the elevator param */
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void __init load_default_elevator_module(void)
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{
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struct elevator_type *e;
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if (!chosen_elevator[0])
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return;
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spin_lock(&elv_list_lock);
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e = elevator_find(chosen_elevator);
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spin_unlock(&elv_list_lock);
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if (!e)
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request_module("%s-iosched", chosen_elevator);
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}
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static struct kobj_type elv_ktype;
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struct elevator_queue *elevator_alloc(struct request_queue *q,
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struct elevator_type *e)
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{
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struct elevator_queue *eq;
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eq = kzalloc_node(sizeof(*eq), GFP_KERNEL, q->node);
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if (unlikely(!eq))
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return NULL;
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eq->type = e;
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kobject_init(&eq->kobj, &elv_ktype);
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mutex_init(&eq->sysfs_lock);
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hash_init(eq->hash);
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eq->uses_mq = e->uses_mq;
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return eq;
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}
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EXPORT_SYMBOL(elevator_alloc);
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static void elevator_release(struct kobject *kobj)
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{
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struct elevator_queue *e;
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e = container_of(kobj, struct elevator_queue, kobj);
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elevator_put(e->type);
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kfree(e);
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}
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int elevator_init(struct request_queue *q, char *name)
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{
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struct elevator_type *e = NULL;
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int err;
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/*
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* q->sysfs_lock must be held to provide mutual exclusion between
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* elevator_switch() and here.
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*/
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lockdep_assert_held(&q->sysfs_lock);
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if (unlikely(q->elevator))
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return 0;
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INIT_LIST_HEAD(&q->queue_head);
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q->last_merge = NULL;
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q->end_sector = 0;
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q->boundary_rq = NULL;
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if (name) {
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e = elevator_get(name, true);
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if (!e)
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return -EINVAL;
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}
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/*
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* Use the default elevator specified by config boot param or
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* config option. Don't try to load modules as we could be running
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* off async and request_module() isn't allowed from async.
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*/
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if (!e && *chosen_elevator) {
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e = elevator_get(chosen_elevator, false);
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if (!e)
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printk(KERN_ERR "I/O scheduler %s not found\n",
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chosen_elevator);
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}
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if (!e) {
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if (q->mq_ops && q->nr_hw_queues == 1)
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e = elevator_get(CONFIG_DEFAULT_SQ_IOSCHED, false);
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else if (q->mq_ops)
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e = elevator_get(CONFIG_DEFAULT_MQ_IOSCHED, false);
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else
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e = elevator_get(CONFIG_DEFAULT_IOSCHED, false);
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if (!e) {
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printk(KERN_ERR
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"Default I/O scheduler not found. " \
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"Using noop/none.\n");
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e = elevator_get("noop", false);
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}
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}
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if (e->uses_mq) {
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err = blk_mq_sched_setup(q);
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if (!err)
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err = e->ops.mq.init_sched(q, e);
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} else
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err = e->ops.sq.elevator_init_fn(q, e);
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if (err) {
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if (e->uses_mq)
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blk_mq_sched_teardown(q);
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elevator_put(e);
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}
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return err;
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}
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EXPORT_SYMBOL(elevator_init);
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void elevator_exit(struct elevator_queue *e)
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{
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mutex_lock(&e->sysfs_lock);
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if (e->uses_mq && e->type->ops.mq.exit_sched)
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e->type->ops.mq.exit_sched(e);
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else if (!e->uses_mq && e->type->ops.sq.elevator_exit_fn)
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e->type->ops.sq.elevator_exit_fn(e);
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mutex_unlock(&e->sysfs_lock);
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kobject_put(&e->kobj);
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}
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EXPORT_SYMBOL(elevator_exit);
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static inline void __elv_rqhash_del(struct request *rq)
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{
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hash_del(&rq->hash);
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rq->rq_flags &= ~RQF_HASHED;
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}
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void elv_rqhash_del(struct request_queue *q, struct request *rq)
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{
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if (ELV_ON_HASH(rq))
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__elv_rqhash_del(rq);
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}
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EXPORT_SYMBOL_GPL(elv_rqhash_del);
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void elv_rqhash_add(struct request_queue *q, struct request *rq)
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{
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struct elevator_queue *e = q->elevator;
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BUG_ON(ELV_ON_HASH(rq));
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hash_add(e->hash, &rq->hash, rq_hash_key(rq));
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rq->rq_flags |= RQF_HASHED;
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}
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EXPORT_SYMBOL_GPL(elv_rqhash_add);
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void elv_rqhash_reposition(struct request_queue *q, struct request *rq)
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{
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__elv_rqhash_del(rq);
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elv_rqhash_add(q, rq);
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}
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struct request *elv_rqhash_find(struct request_queue *q, sector_t offset)
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{
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struct elevator_queue *e = q->elevator;
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struct hlist_node *next;
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struct request *rq;
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hash_for_each_possible_safe(e->hash, rq, next, hash, offset) {
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BUG_ON(!ELV_ON_HASH(rq));
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if (unlikely(!rq_mergeable(rq))) {
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__elv_rqhash_del(rq);
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continue;
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}
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if (rq_hash_key(rq) == offset)
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return rq;
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}
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return NULL;
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}
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/*
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* RB-tree support functions for inserting/lookup/removal of requests
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* in a sorted RB tree.
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*/
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void elv_rb_add(struct rb_root *root, struct request *rq)
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{
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struct rb_node **p = &root->rb_node;
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struct rb_node *parent = NULL;
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struct request *__rq;
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while (*p) {
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parent = *p;
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__rq = rb_entry(parent, struct request, rb_node);
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if (blk_rq_pos(rq) < blk_rq_pos(__rq))
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p = &(*p)->rb_left;
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else if (blk_rq_pos(rq) >= blk_rq_pos(__rq))
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p = &(*p)->rb_right;
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}
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rb_link_node(&rq->rb_node, parent, p);
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rb_insert_color(&rq->rb_node, root);
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}
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EXPORT_SYMBOL(elv_rb_add);
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void elv_rb_del(struct rb_root *root, struct request *rq)
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{
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BUG_ON(RB_EMPTY_NODE(&rq->rb_node));
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rb_erase(&rq->rb_node, root);
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RB_CLEAR_NODE(&rq->rb_node);
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}
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EXPORT_SYMBOL(elv_rb_del);
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struct request *elv_rb_find(struct rb_root *root, sector_t sector)
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{
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struct rb_node *n = root->rb_node;
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struct request *rq;
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while (n) {
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rq = rb_entry(n, struct request, rb_node);
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if (sector < blk_rq_pos(rq))
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n = n->rb_left;
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else if (sector > blk_rq_pos(rq))
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n = n->rb_right;
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else
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return rq;
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}
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return NULL;
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}
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EXPORT_SYMBOL(elv_rb_find);
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/*
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* Insert rq into dispatch queue of q. Queue lock must be held on
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* entry. rq is sort instead into the dispatch queue. To be used by
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* specific elevators.
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*/
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void elv_dispatch_sort(struct request_queue *q, struct request *rq)
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{
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sector_t boundary;
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struct list_head *entry;
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if (q->last_merge == rq)
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q->last_merge = NULL;
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elv_rqhash_del(q, rq);
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q->nr_sorted--;
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boundary = q->end_sector;
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list_for_each_prev(entry, &q->queue_head) {
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struct request *pos = list_entry_rq(entry);
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if (req_op(rq) != req_op(pos))
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break;
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if (rq_data_dir(rq) != rq_data_dir(pos))
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break;
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if (pos->rq_flags & (RQF_STARTED | RQF_SOFTBARRIER))
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break;
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if (blk_rq_pos(rq) >= boundary) {
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if (blk_rq_pos(pos) < boundary)
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continue;
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} else {
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if (blk_rq_pos(pos) >= boundary)
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break;
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}
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if (blk_rq_pos(rq) >= blk_rq_pos(pos))
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break;
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}
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list_add(&rq->queuelist, entry);
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}
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EXPORT_SYMBOL(elv_dispatch_sort);
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/*
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* Insert rq into dispatch queue of q. Queue lock must be held on
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* entry. rq is added to the back of the dispatch queue. To be used by
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* specific elevators.
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*/
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void elv_dispatch_add_tail(struct request_queue *q, struct request *rq)
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{
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if (q->last_merge == rq)
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q->last_merge = NULL;
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elv_rqhash_del(q, rq);
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q->nr_sorted--;
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q->end_sector = rq_end_sector(rq);
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q->boundary_rq = rq;
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list_add_tail(&rq->queuelist, &q->queue_head);
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}
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EXPORT_SYMBOL(elv_dispatch_add_tail);
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enum elv_merge elv_merge(struct request_queue *q, struct request **req,
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struct bio *bio)
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{
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struct elevator_queue *e = q->elevator;
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struct request *__rq;
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/*
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* Levels of merges:
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* nomerges: No merges at all attempted
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* noxmerges: Only simple one-hit cache try
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* merges: All merge tries attempted
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*/
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if (blk_queue_nomerges(q) || !bio_mergeable(bio))
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return ELEVATOR_NO_MERGE;
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/*
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* First try one-hit cache.
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*/
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if (q->last_merge && elv_bio_merge_ok(q->last_merge, bio)) {
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enum elv_merge ret = blk_try_merge(q->last_merge, bio);
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if (ret != ELEVATOR_NO_MERGE) {
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*req = q->last_merge;
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return ret;
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}
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}
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if (blk_queue_noxmerges(q))
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return ELEVATOR_NO_MERGE;
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/*
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* See if our hash lookup can find a potential backmerge.
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*/
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__rq = elv_rqhash_find(q, bio->bi_iter.bi_sector);
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if (__rq && elv_bio_merge_ok(__rq, bio)) {
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*req = __rq;
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return ELEVATOR_BACK_MERGE;
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}
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if (e->uses_mq && e->type->ops.mq.request_merge)
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return e->type->ops.mq.request_merge(q, req, bio);
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else if (!e->uses_mq && e->type->ops.sq.elevator_merge_fn)
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return e->type->ops.sq.elevator_merge_fn(q, req, bio);
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return ELEVATOR_NO_MERGE;
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}
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/*
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* Attempt to do an insertion back merge. Only check for the case where
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* we can append 'rq' to an existing request, so we can throw 'rq' away
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* afterwards.
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*
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* Returns true if we merged, false otherwise
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*/
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bool elv_attempt_insert_merge(struct request_queue *q, struct request *rq)
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{
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struct request *__rq;
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bool ret;
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if (blk_queue_nomerges(q))
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return false;
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/*
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* First try one-hit cache.
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*/
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if (q->last_merge && blk_attempt_req_merge(q, q->last_merge, rq))
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return true;
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if (blk_queue_noxmerges(q))
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return false;
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ret = false;
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/*
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* See if our hash lookup can find a potential backmerge.
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*/
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while (1) {
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__rq = elv_rqhash_find(q, blk_rq_pos(rq));
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if (!__rq || !blk_attempt_req_merge(q, __rq, rq))
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break;
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/* The merged request could be merged with others, try again */
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ret = true;
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rq = __rq;
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}
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return ret;
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}
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|
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void elv_merged_request(struct request_queue *q, struct request *rq,
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enum elv_merge type)
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{
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struct elevator_queue *e = q->elevator;
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if (e->uses_mq && e->type->ops.mq.request_merged)
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e->type->ops.mq.request_merged(q, rq, type);
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else if (!e->uses_mq && e->type->ops.sq.elevator_merged_fn)
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e->type->ops.sq.elevator_merged_fn(q, rq, type);
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if (type == ELEVATOR_BACK_MERGE)
|
|
elv_rqhash_reposition(q, rq);
|
|
|
|
q->last_merge = rq;
|
|
}
|
|
|
|
void elv_merge_requests(struct request_queue *q, struct request *rq,
|
|
struct request *next)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
bool next_sorted = false;
|
|
|
|
if (e->uses_mq && e->type->ops.mq.requests_merged)
|
|
e->type->ops.mq.requests_merged(q, rq, next);
|
|
else if (e->type->ops.sq.elevator_merge_req_fn) {
|
|
next_sorted = (__force bool)(next->rq_flags & RQF_SORTED);
|
|
if (next_sorted)
|
|
e->type->ops.sq.elevator_merge_req_fn(q, rq, next);
|
|
}
|
|
|
|
elv_rqhash_reposition(q, rq);
|
|
|
|
if (next_sorted) {
|
|
elv_rqhash_del(q, next);
|
|
q->nr_sorted--;
|
|
}
|
|
|
|
q->last_merge = rq;
|
|
}
|
|
|
|
void elv_bio_merged(struct request_queue *q, struct request *rq,
|
|
struct bio *bio)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
|
|
if (WARN_ON_ONCE(e->uses_mq))
|
|
return;
|
|
|
|
if (e->type->ops.sq.elevator_bio_merged_fn)
|
|
e->type->ops.sq.elevator_bio_merged_fn(q, rq, bio);
|
|
}
|
|
|
|
#ifdef CONFIG_PM
|
|
static void blk_pm_requeue_request(struct request *rq)
|
|
{
|
|
if (rq->q->dev && !(rq->rq_flags & RQF_PM))
|
|
rq->q->nr_pending--;
|
|
}
|
|
|
|
static void blk_pm_add_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
if (q->dev && !(rq->rq_flags & RQF_PM) && q->nr_pending++ == 0 &&
|
|
(q->rpm_status == RPM_SUSPENDED || q->rpm_status == RPM_SUSPENDING))
|
|
pm_request_resume(q->dev);
|
|
}
|
|
#else
|
|
static inline void blk_pm_requeue_request(struct request *rq) {}
|
|
static inline void blk_pm_add_request(struct request_queue *q,
|
|
struct request *rq)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
void elv_requeue_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
/*
|
|
* it already went through dequeue, we need to decrement the
|
|
* in_flight count again
|
|
*/
|
|
if (blk_account_rq(rq)) {
|
|
q->in_flight[rq_is_sync(rq)]--;
|
|
if (rq->rq_flags & RQF_SORTED)
|
|
elv_deactivate_rq(q, rq);
|
|
}
|
|
|
|
rq->rq_flags &= ~RQF_STARTED;
|
|
|
|
blk_pm_requeue_request(rq);
|
|
|
|
__elv_add_request(q, rq, ELEVATOR_INSERT_REQUEUE);
|
|
}
|
|
|
|
void elv_drain_elevator(struct request_queue *q)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
static int printed;
|
|
|
|
if (WARN_ON_ONCE(e->uses_mq))
|
|
return;
|
|
|
|
lockdep_assert_held(q->queue_lock);
|
|
|
|
while (e->type->ops.sq.elevator_dispatch_fn(q, 1))
|
|
;
|
|
if (q->nr_sorted && printed++ < 10) {
|
|
printk(KERN_ERR "%s: forced dispatching is broken "
|
|
"(nr_sorted=%u), please report this\n",
|
|
q->elevator->type->elevator_name, q->nr_sorted);
|
|
}
|
|
}
|
|
|
|
void __elv_add_request(struct request_queue *q, struct request *rq, int where)
|
|
{
|
|
trace_block_rq_insert(q, rq);
|
|
|
|
blk_pm_add_request(q, rq);
|
|
|
|
rq->q = q;
|
|
|
|
if (rq->rq_flags & RQF_SOFTBARRIER) {
|
|
/* barriers are scheduling boundary, update end_sector */
|
|
if (!blk_rq_is_passthrough(rq)) {
|
|
q->end_sector = rq_end_sector(rq);
|
|
q->boundary_rq = rq;
|
|
}
|
|
} else if (!(rq->rq_flags & RQF_ELVPRIV) &&
|
|
(where == ELEVATOR_INSERT_SORT ||
|
|
where == ELEVATOR_INSERT_SORT_MERGE))
|
|
where = ELEVATOR_INSERT_BACK;
|
|
|
|
switch (where) {
|
|
case ELEVATOR_INSERT_REQUEUE:
|
|
case ELEVATOR_INSERT_FRONT:
|
|
rq->rq_flags |= RQF_SOFTBARRIER;
|
|
list_add(&rq->queuelist, &q->queue_head);
|
|
break;
|
|
|
|
case ELEVATOR_INSERT_BACK:
|
|
rq->rq_flags |= RQF_SOFTBARRIER;
|
|
elv_drain_elevator(q);
|
|
list_add_tail(&rq->queuelist, &q->queue_head);
|
|
/*
|
|
* We kick the queue here for the following reasons.
|
|
* - The elevator might have returned NULL previously
|
|
* to delay requests and returned them now. As the
|
|
* queue wasn't empty before this request, ll_rw_blk
|
|
* won't run the queue on return, resulting in hang.
|
|
* - Usually, back inserted requests won't be merged
|
|
* with anything. There's no point in delaying queue
|
|
* processing.
|
|
*/
|
|
__blk_run_queue(q);
|
|
break;
|
|
|
|
case ELEVATOR_INSERT_SORT_MERGE:
|
|
/*
|
|
* If we succeed in merging this request with one in the
|
|
* queue already, we are done - rq has now been freed,
|
|
* so no need to do anything further.
|
|
*/
|
|
if (elv_attempt_insert_merge(q, rq))
|
|
break;
|
|
case ELEVATOR_INSERT_SORT:
|
|
BUG_ON(blk_rq_is_passthrough(rq));
|
|
rq->rq_flags |= RQF_SORTED;
|
|
q->nr_sorted++;
|
|
if (rq_mergeable(rq)) {
|
|
elv_rqhash_add(q, rq);
|
|
if (!q->last_merge)
|
|
q->last_merge = rq;
|
|
}
|
|
|
|
/*
|
|
* Some ioscheds (cfq) run q->request_fn directly, so
|
|
* rq cannot be accessed after calling
|
|
* elevator_add_req_fn.
|
|
*/
|
|
q->elevator->type->ops.sq.elevator_add_req_fn(q, rq);
|
|
break;
|
|
|
|
case ELEVATOR_INSERT_FLUSH:
|
|
rq->rq_flags |= RQF_SOFTBARRIER;
|
|
blk_insert_flush(rq);
|
|
break;
|
|
default:
|
|
printk(KERN_ERR "%s: bad insertion point %d\n",
|
|
__func__, where);
|
|
BUG();
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(__elv_add_request);
|
|
|
|
void elv_add_request(struct request_queue *q, struct request *rq, int where)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(q->queue_lock, flags);
|
|
__elv_add_request(q, rq, where);
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
}
|
|
EXPORT_SYMBOL(elv_add_request);
|
|
|
|
struct request *elv_latter_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
|
|
if (e->uses_mq && e->type->ops.mq.next_request)
|
|
return e->type->ops.mq.next_request(q, rq);
|
|
else if (!e->uses_mq && e->type->ops.sq.elevator_latter_req_fn)
|
|
return e->type->ops.sq.elevator_latter_req_fn(q, rq);
|
|
|
|
return NULL;
|
|
}
|
|
|
|
struct request *elv_former_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
|
|
if (e->uses_mq && e->type->ops.mq.former_request)
|
|
return e->type->ops.mq.former_request(q, rq);
|
|
if (!e->uses_mq && e->type->ops.sq.elevator_former_req_fn)
|
|
return e->type->ops.sq.elevator_former_req_fn(q, rq);
|
|
return NULL;
|
|
}
|
|
|
|
int elv_set_request(struct request_queue *q, struct request *rq,
|
|
struct bio *bio, gfp_t gfp_mask)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
|
|
if (WARN_ON_ONCE(e->uses_mq))
|
|
return 0;
|
|
|
|
if (e->type->ops.sq.elevator_set_req_fn)
|
|
return e->type->ops.sq.elevator_set_req_fn(q, rq, bio, gfp_mask);
|
|
return 0;
|
|
}
|
|
|
|
void elv_put_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
|
|
if (WARN_ON_ONCE(e->uses_mq))
|
|
return;
|
|
|
|
if (e->type->ops.sq.elevator_put_req_fn)
|
|
e->type->ops.sq.elevator_put_req_fn(rq);
|
|
}
|
|
|
|
int elv_may_queue(struct request_queue *q, unsigned int op)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
|
|
if (WARN_ON_ONCE(e->uses_mq))
|
|
return 0;
|
|
|
|
if (e->type->ops.sq.elevator_may_queue_fn)
|
|
return e->type->ops.sq.elevator_may_queue_fn(q, op);
|
|
|
|
return ELV_MQUEUE_MAY;
|
|
}
|
|
|
|
void elv_completed_request(struct request_queue *q, struct request *rq)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
|
|
if (WARN_ON_ONCE(e->uses_mq))
|
|
return;
|
|
|
|
/*
|
|
* request is released from the driver, io must be done
|
|
*/
|
|
if (blk_account_rq(rq)) {
|
|
q->in_flight[rq_is_sync(rq)]--;
|
|
if ((rq->rq_flags & RQF_SORTED) &&
|
|
e->type->ops.sq.elevator_completed_req_fn)
|
|
e->type->ops.sq.elevator_completed_req_fn(q, rq);
|
|
}
|
|
}
|
|
|
|
#define to_elv(atr) container_of((atr), struct elv_fs_entry, attr)
|
|
|
|
static ssize_t
|
|
elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
|
|
{
|
|
struct elv_fs_entry *entry = to_elv(attr);
|
|
struct elevator_queue *e;
|
|
ssize_t error;
|
|
|
|
if (!entry->show)
|
|
return -EIO;
|
|
|
|
e = container_of(kobj, struct elevator_queue, kobj);
|
|
mutex_lock(&e->sysfs_lock);
|
|
error = e->type ? entry->show(e, page) : -ENOENT;
|
|
mutex_unlock(&e->sysfs_lock);
|
|
return error;
|
|
}
|
|
|
|
static ssize_t
|
|
elv_attr_store(struct kobject *kobj, struct attribute *attr,
|
|
const char *page, size_t length)
|
|
{
|
|
struct elv_fs_entry *entry = to_elv(attr);
|
|
struct elevator_queue *e;
|
|
ssize_t error;
|
|
|
|
if (!entry->store)
|
|
return -EIO;
|
|
|
|
e = container_of(kobj, struct elevator_queue, kobj);
|
|
mutex_lock(&e->sysfs_lock);
|
|
error = e->type ? entry->store(e, page, length) : -ENOENT;
|
|
mutex_unlock(&e->sysfs_lock);
|
|
return error;
|
|
}
|
|
|
|
static const struct sysfs_ops elv_sysfs_ops = {
|
|
.show = elv_attr_show,
|
|
.store = elv_attr_store,
|
|
};
|
|
|
|
static struct kobj_type elv_ktype = {
|
|
.sysfs_ops = &elv_sysfs_ops,
|
|
.release = elevator_release,
|
|
};
|
|
|
|
int elv_register_queue(struct request_queue *q)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
int error;
|
|
|
|
error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched");
|
|
if (!error) {
|
|
struct elv_fs_entry *attr = e->type->elevator_attrs;
|
|
if (attr) {
|
|
while (attr->attr.name) {
|
|
if (sysfs_create_file(&e->kobj, &attr->attr))
|
|
break;
|
|
attr++;
|
|
}
|
|
}
|
|
kobject_uevent(&e->kobj, KOBJ_ADD);
|
|
e->registered = 1;
|
|
if (!e->uses_mq && e->type->ops.sq.elevator_registered_fn)
|
|
e->type->ops.sq.elevator_registered_fn(q);
|
|
}
|
|
return error;
|
|
}
|
|
EXPORT_SYMBOL(elv_register_queue);
|
|
|
|
void elv_unregister_queue(struct request_queue *q)
|
|
{
|
|
if (q) {
|
|
struct elevator_queue *e = q->elevator;
|
|
|
|
kobject_uevent(&e->kobj, KOBJ_REMOVE);
|
|
kobject_del(&e->kobj);
|
|
e->registered = 0;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(elv_unregister_queue);
|
|
|
|
int elv_register(struct elevator_type *e)
|
|
{
|
|
char *def = "";
|
|
|
|
/* create icq_cache if requested */
|
|
if (e->icq_size) {
|
|
if (WARN_ON(e->icq_size < sizeof(struct io_cq)) ||
|
|
WARN_ON(e->icq_align < __alignof__(struct io_cq)))
|
|
return -EINVAL;
|
|
|
|
snprintf(e->icq_cache_name, sizeof(e->icq_cache_name),
|
|
"%s_io_cq", e->elevator_name);
|
|
e->icq_cache = kmem_cache_create(e->icq_cache_name, e->icq_size,
|
|
e->icq_align, 0, NULL);
|
|
if (!e->icq_cache)
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/* register, don't allow duplicate names */
|
|
spin_lock(&elv_list_lock);
|
|
if (elevator_find(e->elevator_name)) {
|
|
spin_unlock(&elv_list_lock);
|
|
if (e->icq_cache)
|
|
kmem_cache_destroy(e->icq_cache);
|
|
return -EBUSY;
|
|
}
|
|
list_add_tail(&e->list, &elv_list);
|
|
spin_unlock(&elv_list_lock);
|
|
|
|
/* print pretty message */
|
|
if (!strcmp(e->elevator_name, chosen_elevator) ||
|
|
(!*chosen_elevator &&
|
|
!strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED)))
|
|
def = " (default)";
|
|
|
|
printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name,
|
|
def);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(elv_register);
|
|
|
|
void elv_unregister(struct elevator_type *e)
|
|
{
|
|
/* unregister */
|
|
spin_lock(&elv_list_lock);
|
|
list_del_init(&e->list);
|
|
spin_unlock(&elv_list_lock);
|
|
|
|
/*
|
|
* Destroy icq_cache if it exists. icq's are RCU managed. Make
|
|
* sure all RCU operations are complete before proceeding.
|
|
*/
|
|
if (e->icq_cache) {
|
|
rcu_barrier();
|
|
kmem_cache_destroy(e->icq_cache);
|
|
e->icq_cache = NULL;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(elv_unregister);
|
|
|
|
/*
|
|
* switch to new_e io scheduler. be careful not to introduce deadlocks -
|
|
* we don't free the old io scheduler, before we have allocated what we
|
|
* need for the new one. this way we have a chance of going back to the old
|
|
* one, if the new one fails init for some reason.
|
|
*/
|
|
static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
|
|
{
|
|
struct elevator_queue *old = q->elevator;
|
|
bool old_registered = false;
|
|
int err;
|
|
|
|
if (q->mq_ops) {
|
|
blk_mq_freeze_queue(q);
|
|
blk_mq_quiesce_queue(q);
|
|
}
|
|
|
|
/*
|
|
* Turn on BYPASS and drain all requests w/ elevator private data.
|
|
* Block layer doesn't call into a quiesced elevator - all requests
|
|
* are directly put on the dispatch list without elevator data
|
|
* using INSERT_BACK. All requests have SOFTBARRIER set and no
|
|
* merge happens either.
|
|
*/
|
|
if (old) {
|
|
old_registered = old->registered;
|
|
|
|
if (old->uses_mq)
|
|
blk_mq_sched_teardown(q);
|
|
|
|
if (!q->mq_ops)
|
|
blk_queue_bypass_start(q);
|
|
|
|
/* unregister and clear all auxiliary data of the old elevator */
|
|
if (old_registered)
|
|
elv_unregister_queue(q);
|
|
|
|
spin_lock_irq(q->queue_lock);
|
|
ioc_clear_queue(q);
|
|
spin_unlock_irq(q->queue_lock);
|
|
}
|
|
|
|
/* allocate, init and register new elevator */
|
|
if (new_e) {
|
|
if (new_e->uses_mq) {
|
|
err = blk_mq_sched_setup(q);
|
|
if (!err)
|
|
err = new_e->ops.mq.init_sched(q, new_e);
|
|
} else
|
|
err = new_e->ops.sq.elevator_init_fn(q, new_e);
|
|
if (err)
|
|
goto fail_init;
|
|
|
|
err = elv_register_queue(q);
|
|
if (err)
|
|
goto fail_register;
|
|
} else
|
|
q->elevator = NULL;
|
|
|
|
/* done, kill the old one and finish */
|
|
if (old) {
|
|
elevator_exit(old);
|
|
if (!q->mq_ops)
|
|
blk_queue_bypass_end(q);
|
|
}
|
|
|
|
if (q->mq_ops) {
|
|
blk_mq_unfreeze_queue(q);
|
|
blk_mq_start_stopped_hw_queues(q, true);
|
|
}
|
|
|
|
if (new_e)
|
|
blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name);
|
|
else
|
|
blk_add_trace_msg(q, "elv switch: none");
|
|
|
|
return 0;
|
|
|
|
fail_register:
|
|
if (q->mq_ops)
|
|
blk_mq_sched_teardown(q);
|
|
elevator_exit(q->elevator);
|
|
fail_init:
|
|
/* switch failed, restore and re-register old elevator */
|
|
if (old) {
|
|
q->elevator = old;
|
|
elv_register_queue(q);
|
|
if (!q->mq_ops)
|
|
blk_queue_bypass_end(q);
|
|
}
|
|
if (q->mq_ops) {
|
|
blk_mq_unfreeze_queue(q);
|
|
blk_mq_start_stopped_hw_queues(q, true);
|
|
}
|
|
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* Switch this queue to the given IO scheduler.
|
|
*/
|
|
static int __elevator_change(struct request_queue *q, const char *name)
|
|
{
|
|
char elevator_name[ELV_NAME_MAX];
|
|
struct elevator_type *e;
|
|
|
|
/*
|
|
* Special case for mq, turn off scheduling
|
|
*/
|
|
if (q->mq_ops && !strncmp(name, "none", 4))
|
|
return elevator_switch(q, NULL);
|
|
|
|
strlcpy(elevator_name, name, sizeof(elevator_name));
|
|
e = elevator_get(strstrip(elevator_name), true);
|
|
if (!e) {
|
|
printk(KERN_ERR "elevator: type %s not found\n", elevator_name);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (q->elevator &&
|
|
!strcmp(elevator_name, q->elevator->type->elevator_name)) {
|
|
elevator_put(e);
|
|
return 0;
|
|
}
|
|
|
|
if (!e->uses_mq && q->mq_ops) {
|
|
elevator_put(e);
|
|
return -EINVAL;
|
|
}
|
|
if (e->uses_mq && !q->mq_ops) {
|
|
elevator_put(e);
|
|
return -EINVAL;
|
|
}
|
|
|
|
return elevator_switch(q, e);
|
|
}
|
|
|
|
int elevator_change(struct request_queue *q, const char *name)
|
|
{
|
|
int ret;
|
|
|
|
/* Protect q->elevator from elevator_init() */
|
|
mutex_lock(&q->sysfs_lock);
|
|
ret = __elevator_change(q, name);
|
|
mutex_unlock(&q->sysfs_lock);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(elevator_change);
|
|
|
|
ssize_t elv_iosched_store(struct request_queue *q, const char *name,
|
|
size_t count)
|
|
{
|
|
int ret;
|
|
|
|
if (!(q->mq_ops || q->request_fn))
|
|
return count;
|
|
|
|
ret = __elevator_change(q, name);
|
|
if (!ret)
|
|
return count;
|
|
|
|
printk(KERN_ERR "elevator: switch to %s failed\n", name);
|
|
return ret;
|
|
}
|
|
|
|
ssize_t elv_iosched_show(struct request_queue *q, char *name)
|
|
{
|
|
struct elevator_queue *e = q->elevator;
|
|
struct elevator_type *elv = NULL;
|
|
struct elevator_type *__e;
|
|
int len = 0;
|
|
|
|
if (!blk_queue_stackable(q))
|
|
return sprintf(name, "none\n");
|
|
|
|
if (!q->elevator)
|
|
len += sprintf(name+len, "[none] ");
|
|
else
|
|
elv = e->type;
|
|
|
|
spin_lock(&elv_list_lock);
|
|
list_for_each_entry(__e, &elv_list, list) {
|
|
if (elv && !strcmp(elv->elevator_name, __e->elevator_name)) {
|
|
len += sprintf(name+len, "[%s] ", elv->elevator_name);
|
|
continue;
|
|
}
|
|
if (__e->uses_mq && q->mq_ops)
|
|
len += sprintf(name+len, "%s ", __e->elevator_name);
|
|
else if (!__e->uses_mq && !q->mq_ops)
|
|
len += sprintf(name+len, "%s ", __e->elevator_name);
|
|
}
|
|
spin_unlock(&elv_list_lock);
|
|
|
|
if (q->mq_ops && q->elevator)
|
|
len += sprintf(name+len, "none");
|
|
|
|
len += sprintf(len+name, "\n");
|
|
return len;
|
|
}
|
|
|
|
struct request *elv_rb_former_request(struct request_queue *q,
|
|
struct request *rq)
|
|
{
|
|
struct rb_node *rbprev = rb_prev(&rq->rb_node);
|
|
|
|
if (rbprev)
|
|
return rb_entry_rq(rbprev);
|
|
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL(elv_rb_former_request);
|
|
|
|
struct request *elv_rb_latter_request(struct request_queue *q,
|
|
struct request *rq)
|
|
{
|
|
struct rb_node *rbnext = rb_next(&rq->rb_node);
|
|
|
|
if (rbnext)
|
|
return rb_entry_rq(rbnext);
|
|
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL(elv_rb_latter_request);
|