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block/elevator.c
23.7 KB
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/* |
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* Block device elevator/IO-scheduler. * * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE * |
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* 30042000 Jens Axboe <axboe@kernel.dk> : |
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* * Split the elevator a bit so that it is possible to choose a different * one or even write a new "plug in". There are three pieces: * - elevator_fn, inserts a new request in the queue list * - elevator_merge_fn, decides whether a new buffer can be merged with * an existing request * - elevator_dequeue_fn, called when a request is taken off the active list * * 20082000 Dave Jones <davej@suse.de> : * Removed tests for max-bomb-segments, which was breaking elvtune * when run without -bN * * Jens: * - Rework again to work with bio instead of buffer_heads * - loose bi_dev comparisons, partition handling is right now * - completely modularize elevator setup and teardown * */ #include <linux/kernel.h> #include <linux/fs.h> #include <linux/blkdev.h> #include <linux/elevator.h> #include <linux/bio.h> |
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#include <linux/module.h> #include <linux/slab.h> #include <linux/init.h> #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 <trace/events/block.h> |
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#include "blk.h" |
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#include "blk-cgroup.h" |
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static DEFINE_SPINLOCK(elv_list_lock); static LIST_HEAD(elv_list); /* |
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* Merge hash stuff. */ |
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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 * merged with rq. */ static int elv_iosched_allow_merge(struct request *rq, struct bio *bio) { |
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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->type->ops.elevator_allow_merge_fn) return e->type->ops.elevator_allow_merge_fn(q, rq, bio); |
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return 1; } /* |
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* can we safely merge with this request? */ |
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bool elv_rq_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 0; |
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if (!elv_iosched_allow_merge(rq, bio)) return 0; |
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return 1; |
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} EXPORT_SYMBOL(elv_rq_merge_ok); |
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static struct elevator_type *elevator_find(const char *name) { |
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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)) return e; |
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} |
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return NULL; |
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} static void elevator_put(struct elevator_type *e) { module_put(e->elevator_owner); } |
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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); e = elevator_find(name); } |
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if (e && !try_module_get(e->elevator_owner)) e = NULL; |
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spin_unlock(&elv_list_lock); |
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return e; } |
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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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/* * Be backwards-compatible with previous kernels, so users * won't get the wrong elevator. */ |
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strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
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return 1; |
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} __setup("elevator=", elevator_setup); |
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/* called during boot to load the elevator chosen by the elevator param */ void __init load_default_elevator_module(void) { struct elevator_type *e; if (!chosen_elevator[0]) return; spin_lock(&elv_list_lock); e = elevator_find(chosen_elevator); spin_unlock(&elv_list_lock); if (!e) request_module("%s-iosched", chosen_elevator); } |
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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)) goto err; |
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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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return eq; |
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err: kfree(eq); elevator_put(e); return NULL; |
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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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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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int elevator_init(struct request_queue *q, char *name) |
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{ struct elevator_type *e = NULL; |
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int err; |
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if (unlikely(q->elevator)) return 0; |
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INIT_LIST_HEAD(&q->queue_head); q->last_merge = NULL; q->end_sector = 0; 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) return -EINVAL; } |
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/* * Use the default elevator specified by config boot param or * config option. Don't try to load modules as we could be running * off async and request_module() isn't allowed from async. */ |
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if (!e && *chosen_elevator) { |
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e = elevator_get(chosen_elevator, false); |
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if (!e) printk(KERN_ERR "I/O scheduler %s not found ", chosen_elevator); } |
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if (!e) { |
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e = elevator_get(CONFIG_DEFAULT_IOSCHED, false); |
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if (!e) { printk(KERN_ERR "Default I/O scheduler not found. " \ "Using noop. "); |
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e = elevator_get("noop", false); |
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} |
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} |
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err = e->ops.elevator_init_fn(q, e); |
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return 0; |
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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->type->ops.elevator_exit_fn) e->type->ops.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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hash_del(&rq->hash); |
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} |
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static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
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{ if (ELV_ON_HASH(rq)) __elv_rqhash_del(rq); } |
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static 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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} |
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static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
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{ __elv_rqhash_del(rq); elv_rqhash_add(q, rq); } |
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static 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)); if (unlikely(!rq_mergeable(rq))) { __elv_rqhash_del(rq); continue; } if (rq_hash_key(rq) == offset) return rq; } return NULL; } |
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/* |
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* RB-tree support functions for inserting/lookup/removal of requests * in a sorted RB tree. */ |
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void elv_rb_add(struct rb_root *root, struct request *rq) |
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{ struct rb_node **p = &root->rb_node; struct rb_node *parent = NULL; struct request *__rq; while (*p) { parent = *p; __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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} rb_link_node(&rq->rb_node, parent, p); rb_insert_color(&rq->rb_node, root); |
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} |
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EXPORT_SYMBOL(elv_rb_add); void elv_rb_del(struct rb_root *root, struct request *rq) { BUG_ON(RB_EMPTY_NODE(&rq->rb_node)); rb_erase(&rq->rb_node, root); RB_CLEAR_NODE(&rq->rb_node); } |
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EXPORT_SYMBOL(elv_rb_del); struct request *elv_rb_find(struct rb_root *root, sector_t sector) { struct rb_node *n = root->rb_node; struct request *rq; while (n) { 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; else return rq; } return NULL; } |
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EXPORT_SYMBOL(elv_rb_find); /* |
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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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{ sector_t boundary; |
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struct list_head *entry; |
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int stop_flags; |
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if (q->last_merge == rq) 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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stop_flags = REQ_SOFTBARRIER | REQ_STARTED; |
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list_for_each_prev(entry, &q->queue_head) { struct request *pos = list_entry_rq(entry); |
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if ((rq->cmd_flags & REQ_DISCARD) != (pos->cmd_flags & REQ_DISCARD)) |
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break; |
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if (rq_data_dir(rq) != rq_data_dir(pos)) break; |
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if (pos->cmd_flags & stop_flags) |
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break; |
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if (blk_rq_pos(rq) >= boundary) { if (blk_rq_pos(pos) < boundary) |
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continue; } else { |
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if (blk_rq_pos(pos) >= boundary) |
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break; } |
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if (blk_rq_pos(rq) >= blk_rq_pos(pos)) |
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break; } list_add(&rq->queuelist, entry); } |
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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 * entry. rq is added to the back of the dispatch queue. To be used by * specific elevators. |
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*/ void elv_dispatch_add_tail(struct request_queue *q, struct request *rq) { if (q->last_merge == rq) q->last_merge = NULL; elv_rqhash_del(q, rq); q->nr_sorted--; q->end_sector = rq_end_sector(rq); q->boundary_rq = rq; list_add_tail(&rq->queuelist, &q->queue_head); } |
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EXPORT_SYMBOL(elv_dispatch_add_tail); |
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int elv_merge(struct request_queue *q, struct request **req, 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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int ret; |
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/* |
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* Levels of merges: * nomerges: No merges at all attempted * noxmerges: Only simple one-hit cache try * merges: All merge tries attempted */ if (blk_queue_nomerges(q)) return ELEVATOR_NO_MERGE; /* |
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* First try one-hit cache. */ |
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if (q->last_merge && elv_rq_merge_ok(q->last_merge, bio)) { ret = blk_try_merge(q->last_merge, bio); |
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if (ret != ELEVATOR_NO_MERGE) { *req = q->last_merge; return ret; } } |
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if (blk_queue_noxmerges(q)) |
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return ELEVATOR_NO_MERGE; |
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/* * See if our hash lookup can find a potential backmerge. */ __rq = elv_rqhash_find(q, bio->bi_sector); if (__rq && elv_rq_merge_ok(__rq, bio)) { *req = __rq; return ELEVATOR_BACK_MERGE; } |
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if (e->type->ops.elevator_merge_fn) return e->type->ops.elevator_merge_fn(q, req, bio); |
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return ELEVATOR_NO_MERGE; } |
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/* * Attempt to do an insertion back merge. Only check for the case where * we can append 'rq' to an existing request, so we can throw 'rq' away * afterwards. * * Returns true if we merged, false otherwise */ static bool elv_attempt_insert_merge(struct request_queue *q, struct request *rq) { struct request *__rq; |
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bool ret; |
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if (blk_queue_nomerges(q)) return false; /* * First try one-hit cache. */ if (q->last_merge && blk_attempt_req_merge(q, q->last_merge, rq)) return true; if (blk_queue_noxmerges(q)) return false; |
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ret = false; |
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/* * See if our hash lookup can find a potential backmerge. */ |
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while (1) { __rq = elv_rqhash_find(q, blk_rq_pos(rq)); if (!__rq || !blk_attempt_req_merge(q, __rq, rq)) break; /* The merged request could be merged with others, try again */ ret = true; rq = __rq; } |
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return ret; |
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} |
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void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
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{ |
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struct elevator_queue *e = q->elevator; |
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if (e->type->ops.elevator_merged_fn) e->type->ops.elevator_merged_fn(q, rq, type); |
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if (type == ELEVATOR_BACK_MERGE) elv_rqhash_reposition(q, rq); |
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q->last_merge = rq; |
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} |
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void elv_merge_requests(struct request_queue *q, struct request *rq, |
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struct request *next) { |
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struct elevator_queue *e = q->elevator; |
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const int next_sorted = next->cmd_flags & REQ_SORTED; |
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if (next_sorted && e->type->ops.elevator_merge_req_fn) e->type->ops.elevator_merge_req_fn(q, rq, next); |
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elv_rqhash_reposition(q, rq); |
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if (next_sorted) { elv_rqhash_del(q, next); q->nr_sorted--; } |
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q->last_merge = rq; |
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487 |
} |
812d40264
|
488 489 490 491 |
void elv_bio_merged(struct request_queue *q, struct request *rq, struct bio *bio) { struct elevator_queue *e = q->elevator; |
22f746e23
|
492 493 |
if (e->type->ops.elevator_bio_merged_fn) e->type->ops.elevator_bio_merged_fn(q, rq, bio); |
812d40264
|
494 |
} |
c8158819d
|
495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 |
#ifdef CONFIG_PM_RUNTIME static void blk_pm_requeue_request(struct request *rq) { if (rq->q->dev && !(rq->cmd_flags & REQ_PM)) rq->q->nr_pending--; } static void blk_pm_add_request(struct request_queue *q, struct request *rq) { if (q->dev && !(rq->cmd_flags & REQ_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 |
165125e1e
|
515 |
void elv_requeue_request(struct request_queue *q, struct request *rq) |
1da177e4c
|
516 |
{ |
1da177e4c
|
517 518 519 520 |
/* * it already went through dequeue, we need to decrement the * in_flight count again */ |
8922e16cf
|
521 |
if (blk_account_rq(rq)) { |
0a7ae2ff0
|
522 |
q->in_flight[rq_is_sync(rq)]--; |
33659ebba
|
523 |
if (rq->cmd_flags & REQ_SORTED) |
cad975164
|
524 |
elv_deactivate_rq(q, rq); |
8922e16cf
|
525 |
} |
1da177e4c
|
526 |
|
4aff5e233
|
527 |
rq->cmd_flags &= ~REQ_STARTED; |
1da177e4c
|
528 |
|
c8158819d
|
529 |
blk_pm_requeue_request(rq); |
b710a4805
|
530 |
__elv_add_request(q, rq, ELEVATOR_INSERT_REQUEUE); |
1da177e4c
|
531 |
} |
26308eab6
|
532 |
void elv_drain_elevator(struct request_queue *q) |
15853af9f
|
533 534 |
{ static int printed; |
e3c78ca52
|
535 536 |
lockdep_assert_held(q->queue_lock); |
22f746e23
|
537 |
while (q->elevator->type->ops.elevator_dispatch_fn(q, 1)) |
15853af9f
|
538 |
; |
e3c78ca52
|
539 |
if (q->nr_sorted && printed++ < 10) { |
15853af9f
|
540 541 542 |
printk(KERN_ERR "%s: forced dispatching is broken " "(nr_sorted=%u), please report this ", |
22f746e23
|
543 |
q->elevator->type->elevator_name, q->nr_sorted); |
15853af9f
|
544 545 |
} } |
b710a4805
|
546 |
void __elv_add_request(struct request_queue *q, struct request *rq, int where) |
1da177e4c
|
547 |
{ |
5f3ea37c7
|
548 |
trace_block_rq_insert(q, rq); |
2056a782f
|
549 |
|
c8158819d
|
550 |
blk_pm_add_request(q, rq); |
1da177e4c
|
551 |
rq->q = q; |
b710a4805
|
552 553 |
if (rq->cmd_flags & REQ_SOFTBARRIER) { /* barriers are scheduling boundary, update end_sector */ |
e2a60da74
|
554 |
if (rq->cmd_type == REQ_TYPE_FS) { |
b710a4805
|
555 556 557 558 |
q->end_sector = rq_end_sector(rq); q->boundary_rq = rq; } } else if (!(rq->cmd_flags & REQ_ELVPRIV) && |
3aa72873f
|
559 560 |
(where == ELEVATOR_INSERT_SORT || where == ELEVATOR_INSERT_SORT_MERGE)) |
b710a4805
|
561 |
where = ELEVATOR_INSERT_BACK; |
8922e16cf
|
562 |
switch (where) { |
28e7d1845
|
563 |
case ELEVATOR_INSERT_REQUEUE: |
8922e16cf
|
564 |
case ELEVATOR_INSERT_FRONT: |
4aff5e233
|
565 |
rq->cmd_flags |= REQ_SOFTBARRIER; |
8922e16cf
|
566 567 568 569 |
list_add(&rq->queuelist, &q->queue_head); break; case ELEVATOR_INSERT_BACK: |
4aff5e233
|
570 |
rq->cmd_flags |= REQ_SOFTBARRIER; |
15853af9f
|
571 |
elv_drain_elevator(q); |
8922e16cf
|
572 573 574 575 576 577 578 579 580 581 582 |
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. */ |
24ecfbe27
|
583 |
__blk_run_queue(q); |
8922e16cf
|
584 |
break; |
5e84ea3a9
|
585 586 587 588 589 590 591 592 |
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; |
8922e16cf
|
593 |
case ELEVATOR_INSERT_SORT: |
e2a60da74
|
594 |
BUG_ON(rq->cmd_type != REQ_TYPE_FS); |
4aff5e233
|
595 |
rq->cmd_flags |= REQ_SORTED; |
15853af9f
|
596 |
q->nr_sorted++; |
9817064b6
|
597 598 599 600 601 |
if (rq_mergeable(rq)) { elv_rqhash_add(q, rq); if (!q->last_merge) q->last_merge = rq; } |
ca23509fb
|
602 603 604 605 606 |
/* * Some ioscheds (cfq) run q->request_fn directly, so * rq cannot be accessed after calling * elevator_add_req_fn. */ |
22f746e23
|
607 |
q->elevator->type->ops.elevator_add_req_fn(q, rq); |
8922e16cf
|
608 |
break; |
ae1b15396
|
609 610 611 612 |
case ELEVATOR_INSERT_FLUSH: rq->cmd_flags |= REQ_SOFTBARRIER; blk_insert_flush(rq); break; |
8922e16cf
|
613 614 615 |
default: printk(KERN_ERR "%s: bad insertion point %d ", |
24c03d47d
|
616 |
__func__, where); |
8922e16cf
|
617 618 |
BUG(); } |
1da177e4c
|
619 |
} |
2e662b65f
|
620 |
EXPORT_SYMBOL(__elv_add_request); |
7eaceacca
|
621 |
void elv_add_request(struct request_queue *q, struct request *rq, int where) |
1da177e4c
|
622 623 624 625 |
{ unsigned long flags; spin_lock_irqsave(q->queue_lock, flags); |
7eaceacca
|
626 |
__elv_add_request(q, rq, where); |
1da177e4c
|
627 628 |
spin_unlock_irqrestore(q->queue_lock, flags); } |
2e662b65f
|
629 |
EXPORT_SYMBOL(elv_add_request); |
165125e1e
|
630 |
struct request *elv_latter_request(struct request_queue *q, struct request *rq) |
1da177e4c
|
631 |
{ |
b374d18a4
|
632 |
struct elevator_queue *e = q->elevator; |
1da177e4c
|
633 |
|
22f746e23
|
634 635 |
if (e->type->ops.elevator_latter_req_fn) return e->type->ops.elevator_latter_req_fn(q, rq); |
1da177e4c
|
636 637 |
return NULL; } |
165125e1e
|
638 |
struct request *elv_former_request(struct request_queue *q, struct request *rq) |
1da177e4c
|
639 |
{ |
b374d18a4
|
640 |
struct elevator_queue *e = q->elevator; |
1da177e4c
|
641 |
|
22f746e23
|
642 643 |
if (e->type->ops.elevator_former_req_fn) return e->type->ops.elevator_former_req_fn(q, rq); |
1da177e4c
|
644 645 |
return NULL; } |
852c788f8
|
646 647 |
int elv_set_request(struct request_queue *q, struct request *rq, struct bio *bio, gfp_t gfp_mask) |
1da177e4c
|
648 |
{ |
b374d18a4
|
649 |
struct elevator_queue *e = q->elevator; |
1da177e4c
|
650 |
|
22f746e23
|
651 |
if (e->type->ops.elevator_set_req_fn) |
852c788f8
|
652 |
return e->type->ops.elevator_set_req_fn(q, rq, bio, gfp_mask); |
1da177e4c
|
653 654 |
return 0; } |
165125e1e
|
655 |
void elv_put_request(struct request_queue *q, struct request *rq) |
1da177e4c
|
656 |
{ |
b374d18a4
|
657 |
struct elevator_queue *e = q->elevator; |
1da177e4c
|
658 |
|
22f746e23
|
659 660 |
if (e->type->ops.elevator_put_req_fn) e->type->ops.elevator_put_req_fn(rq); |
1da177e4c
|
661 |
} |
165125e1e
|
662 |
int elv_may_queue(struct request_queue *q, int rw) |
1da177e4c
|
663 |
{ |
b374d18a4
|
664 |
struct elevator_queue *e = q->elevator; |
1da177e4c
|
665 |
|
22f746e23
|
666 667 |
if (e->type->ops.elevator_may_queue_fn) return e->type->ops.elevator_may_queue_fn(q, rw); |
1da177e4c
|
668 669 670 |
return ELV_MQUEUE_MAY; } |
11914a53d
|
671 672 673 |
void elv_abort_queue(struct request_queue *q) { struct request *rq; |
ae1b15396
|
674 |
blk_abort_flushes(q); |
11914a53d
|
675 676 677 |
while (!list_empty(&q->queue_head)) { rq = list_entry_rq(q->queue_head.next); rq->cmd_flags |= REQ_QUIET; |
5f3ea37c7
|
678 |
trace_block_rq_abort(q, rq); |
53c663ce0
|
679 680 681 682 683 |
/* * Mark this request as started so we don't trigger * any debug logic in the end I/O path. */ blk_start_request(rq); |
40cbbb781
|
684 |
__blk_end_request_all(rq, -EIO); |
11914a53d
|
685 686 687 |
} } EXPORT_SYMBOL(elv_abort_queue); |
165125e1e
|
688 |
void elv_completed_request(struct request_queue *q, struct request *rq) |
1da177e4c
|
689 |
{ |
b374d18a4
|
690 |
struct elevator_queue *e = q->elevator; |
1da177e4c
|
691 692 693 694 |
/* * request is released from the driver, io must be done */ |
8922e16cf
|
695 |
if (blk_account_rq(rq)) { |
0a7ae2ff0
|
696 |
q->in_flight[rq_is_sync(rq)]--; |
33659ebba
|
697 |
if ((rq->cmd_flags & REQ_SORTED) && |
22f746e23
|
698 699 |
e->type->ops.elevator_completed_req_fn) e->type->ops.elevator_completed_req_fn(q, rq); |
1bc691d35
|
700 |
} |
1da177e4c
|
701 |
} |
3d1ab40f4
|
702 703 704 705 |
#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) |
1da177e4c
|
706 |
{ |
3d1ab40f4
|
707 |
struct elv_fs_entry *entry = to_elv(attr); |
b374d18a4
|
708 |
struct elevator_queue *e; |
3d1ab40f4
|
709 710 711 712 |
ssize_t error; if (!entry->show) return -EIO; |
b374d18a4
|
713 |
e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f4
|
714 |
mutex_lock(&e->sysfs_lock); |
22f746e23
|
715 |
error = e->type ? entry->show(e, page) : -ENOENT; |
3d1ab40f4
|
716 717 718 |
mutex_unlock(&e->sysfs_lock); return error; } |
1da177e4c
|
719 |
|
3d1ab40f4
|
720 721 722 723 |
static ssize_t elv_attr_store(struct kobject *kobj, struct attribute *attr, const char *page, size_t length) { |
3d1ab40f4
|
724 |
struct elv_fs_entry *entry = to_elv(attr); |
b374d18a4
|
725 |
struct elevator_queue *e; |
3d1ab40f4
|
726 |
ssize_t error; |
1da177e4c
|
727 |
|
3d1ab40f4
|
728 729 |
if (!entry->store) return -EIO; |
1da177e4c
|
730 |
|
b374d18a4
|
731 |
e = container_of(kobj, struct elevator_queue, kobj); |
3d1ab40f4
|
732 |
mutex_lock(&e->sysfs_lock); |
22f746e23
|
733 |
error = e->type ? entry->store(e, page, length) : -ENOENT; |
3d1ab40f4
|
734 735 736 |
mutex_unlock(&e->sysfs_lock); return error; } |
52cf25d0a
|
737 |
static const struct sysfs_ops elv_sysfs_ops = { |
3d1ab40f4
|
738 739 740 741 742 743 744 745 |
.show = elv_attr_show, .store = elv_attr_store, }; static struct kobj_type elv_ktype = { .sysfs_ops = &elv_sysfs_ops, .release = elevator_release, }; |
5a5bafdc3
|
746 |
int elv_register_queue(struct request_queue *q) |
3d1ab40f4
|
747 |
{ |
5a5bafdc3
|
748 |
struct elevator_queue *e = q->elevator; |
3d1ab40f4
|
749 |
int error; |
b2d6db587
|
750 |
error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched"); |
3d1ab40f4
|
751 |
if (!error) { |
22f746e23
|
752 |
struct elv_fs_entry *attr = e->type->elevator_attrs; |
3d1ab40f4
|
753 |
if (attr) { |
e572ec7e4
|
754 755 |
while (attr->attr.name) { if (sysfs_create_file(&e->kobj, &attr->attr)) |
3d1ab40f4
|
756 |
break; |
e572ec7e4
|
757 |
attr++; |
3d1ab40f4
|
758 759 760 |
} } kobject_uevent(&e->kobj, KOBJ_ADD); |
430c62fb2
|
761 |
e->registered = 1; |
3d1ab40f4
|
762 763 |
} return error; |
1da177e4c
|
764 |
} |
f8fc877d3
|
765 |
EXPORT_SYMBOL(elv_register_queue); |
bc1c11697
|
766 |
|
1da177e4c
|
767 768 |
void elv_unregister_queue(struct request_queue *q) { |
f8fc877d3
|
769 770 771 772 773 774 775 |
if (q) { struct elevator_queue *e = q->elevator; kobject_uevent(&e->kobj, KOBJ_REMOVE); kobject_del(&e->kobj); e->registered = 0; } |
1da177e4c
|
776 |
} |
01effb0dc
|
777 |
EXPORT_SYMBOL(elv_unregister_queue); |
1da177e4c
|
778 |
|
3d3c2379f
|
779 |
int elv_register(struct elevator_type *e) |
1da177e4c
|
780 |
{ |
1ffb96c58
|
781 |
char *def = ""; |
2a12dcd71
|
782 |
|
3d3c2379f
|
783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 |
/* 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 */ |
2a12dcd71
|
798 |
spin_lock(&elv_list_lock); |
3d3c2379f
|
799 800 801 802 803 804 |
if (elevator_find(e->elevator_name)) { spin_unlock(&elv_list_lock); if (e->icq_cache) kmem_cache_destroy(e->icq_cache); return -EBUSY; } |
1da177e4c
|
805 |
list_add_tail(&e->list, &elv_list); |
2a12dcd71
|
806 |
spin_unlock(&elv_list_lock); |
1da177e4c
|
807 |
|
3d3c2379f
|
808 |
/* print pretty message */ |
5f0039764
|
809 810 811 |
if (!strcmp(e->elevator_name, chosen_elevator) || (!*chosen_elevator && !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED))) |
1ffb96c58
|
812 |
def = " (default)"; |
4eb166d98
|
813 814 815 |
printk(KERN_INFO "io scheduler %s registered%s ", e->elevator_name, def); |
3d3c2379f
|
816 |
return 0; |
1da177e4c
|
817 818 819 820 821 |
} EXPORT_SYMBOL_GPL(elv_register); void elv_unregister(struct elevator_type *e) { |
3d3c2379f
|
822 |
/* unregister */ |
2a12dcd71
|
823 |
spin_lock(&elv_list_lock); |
1da177e4c
|
824 |
list_del_init(&e->list); |
2a12dcd71
|
825 |
spin_unlock(&elv_list_lock); |
3d3c2379f
|
826 827 828 829 830 831 832 833 834 835 |
/* * 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; } |
1da177e4c
|
836 837 838 839 840 841 842 |
} 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 |
cb98fc8bb
|
843 |
* one, if the new one fails init for some reason. |
1da177e4c
|
844 |
*/ |
165125e1e
|
845 |
static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) |
1da177e4c
|
846 |
{ |
5a5bafdc3
|
847 848 |
struct elevator_queue *old = q->elevator; bool registered = old->registered; |
e8989fae3
|
849 |
int err; |
1da177e4c
|
850 |
|
5a5bafdc3
|
851 852 853 854 855 856 857 |
/* * 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. */ |
d732580b4
|
858 |
blk_queue_bypass_start(q); |
cb98fc8bb
|
859 |
|
5a5bafdc3
|
860 861 |
/* unregister and clear all auxiliary data of the old elevator */ if (registered) |
f8fc877d3
|
862 |
elv_unregister_queue(q); |
1da177e4c
|
863 |
|
f8fc877d3
|
864 |
spin_lock_irq(q->queue_lock); |
7e5a87944
|
865 |
ioc_clear_queue(q); |
f8fc877d3
|
866 |
spin_unlock_irq(q->queue_lock); |
5a5bafdc3
|
867 |
/* allocate, init and register new elevator */ |
d50235b7b
|
868 869 |
err = new_e->ops.elevator_init_fn(q, new_e); if (err) |
5a5bafdc3
|
870 |
goto fail_init; |
5a5bafdc3
|
871 872 873 874 875 876 877 878 |
if (registered) { err = elv_register_queue(q); if (err) goto fail_register; } /* done, kill the old one and finish */ elevator_exit(old); |
d732580b4
|
879 |
blk_queue_bypass_end(q); |
75ad23bc0
|
880 |
|
5a5bafdc3
|
881 |
blk_add_trace_msg(q, "elv switch: %s", new_e->elevator_name); |
4722dc52a
|
882 |
|
5dd531a03
|
883 |
return 0; |
1da177e4c
|
884 885 |
fail_register: |
5a5bafdc3
|
886 887 888 889 |
elevator_exit(q->elevator); fail_init: /* switch failed, restore and re-register old elevator */ q->elevator = old; |
1da177e4c
|
890 |
elv_register_queue(q); |
d732580b4
|
891 |
blk_queue_bypass_end(q); |
75ad23bc0
|
892 |
|
5dd531a03
|
893 |
return err; |
1da177e4c
|
894 |
} |
5dd531a03
|
895 896 897 898 |
/* * Switch this queue to the given IO scheduler. */ int elevator_change(struct request_queue *q, const char *name) |
1da177e4c
|
899 900 901 |
{ char elevator_name[ELV_NAME_MAX]; struct elevator_type *e; |
cd43e26f0
|
902 |
if (!q->elevator) |
5dd531a03
|
903 |
return -ENXIO; |
cd43e26f0
|
904 |
|
ee2e992cc
|
905 |
strlcpy(elevator_name, name, sizeof(elevator_name)); |
21c3c5d28
|
906 |
e = elevator_get(strstrip(elevator_name), true); |
1da177e4c
|
907 908 909 910 911 |
if (!e) { printk(KERN_ERR "elevator: type %s not found ", elevator_name); return -EINVAL; } |
22f746e23
|
912 |
if (!strcmp(elevator_name, q->elevator->type->elevator_name)) { |
2ca7d93bb
|
913 |
elevator_put(e); |
5dd531a03
|
914 |
return 0; |
2ca7d93bb
|
915 |
} |
1da177e4c
|
916 |
|
5dd531a03
|
917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 |
return elevator_switch(q, e); } EXPORT_SYMBOL(elevator_change); ssize_t elv_iosched_store(struct request_queue *q, const char *name, size_t count) { int ret; if (!q->elevator) return count; ret = elevator_change(q, name); if (!ret) return count; printk(KERN_ERR "elevator: switch to %s failed ", name); return ret; |
1da177e4c
|
936 |
} |
165125e1e
|
937 |
ssize_t elv_iosched_show(struct request_queue *q, char *name) |
1da177e4c
|
938 |
{ |
b374d18a4
|
939 |
struct elevator_queue *e = q->elevator; |
cd43e26f0
|
940 |
struct elevator_type *elv; |
70cee26e0
|
941 |
struct elevator_type *__e; |
1da177e4c
|
942 |
int len = 0; |
e36f724b4
|
943 |
if (!q->elevator || !blk_queue_stackable(q)) |
cd43e26f0
|
944 945 |
return sprintf(name, "none "); |
22f746e23
|
946 |
elv = e->type; |
cd43e26f0
|
947 |
|
2a12dcd71
|
948 |
spin_lock(&elv_list_lock); |
70cee26e0
|
949 |
list_for_each_entry(__e, &elv_list, list) { |
1da177e4c
|
950 951 952 953 954 |
if (!strcmp(elv->elevator_name, __e->elevator_name)) len += sprintf(name+len, "[%s] ", elv->elevator_name); else len += sprintf(name+len, "%s ", __e->elevator_name); } |
2a12dcd71
|
955 |
spin_unlock(&elv_list_lock); |
1da177e4c
|
956 957 958 959 960 |
len += sprintf(len+name, " "); return len; } |
165125e1e
|
961 962 |
struct request *elv_rb_former_request(struct request_queue *q, struct request *rq) |
2e662b65f
|
963 964 965 966 967 968 969 970 |
{ struct rb_node *rbprev = rb_prev(&rq->rb_node); if (rbprev) return rb_entry_rq(rbprev); return NULL; } |
2e662b65f
|
971 |
EXPORT_SYMBOL(elv_rb_former_request); |
165125e1e
|
972 973 |
struct request *elv_rb_latter_request(struct request_queue *q, struct request *rq) |
2e662b65f
|
974 975 976 977 978 979 980 981 |
{ struct rb_node *rbnext = rb_next(&rq->rb_node); if (rbnext) return rb_entry_rq(rbnext); return NULL; } |
2e662b65f
|
982 |
EXPORT_SYMBOL(elv_rb_latter_request); |