| /* |
| * Block device elevator/IO-scheduler. |
| * |
| * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE |
| * |
| * 30042000 Jens Axboe <axboe@kernel.dk> : |
| * |
| * 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> |
| #include <linux/module.h> |
| #include <linux/slab.h> |
| #include <linux/init.h> |
| #include <linux/compiler.h> |
| #include <linux/blktrace_api.h> |
| #include <linux/hash.h> |
| #include <linux/uaccess.h> |
| |
| #include <trace/events/block.h> |
| |
| #include "blk.h" |
| |
| static DEFINE_SPINLOCK(elv_list_lock); |
| static LIST_HEAD(elv_list); |
| |
| /* |
| * Merge hash stuff. |
| */ |
| static const int elv_hash_shift = 6; |
| #define ELV_HASH_BLOCK(sec) ((sec) >> 3) |
| #define ELV_HASH_FN(sec) \ |
| (hash_long(ELV_HASH_BLOCK((sec)), elv_hash_shift)) |
| #define ELV_HASH_ENTRIES (1 << elv_hash_shift) |
| #define rq_hash_key(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq)) |
| |
| /* |
| * 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) |
| { |
| struct request_queue *q = rq->q; |
| struct elevator_queue *e = q->elevator; |
| |
| if (e->ops->elevator_allow_merge_fn) |
| return e->ops->elevator_allow_merge_fn(q, rq, bio); |
| |
| return 1; |
| } |
| |
| /* |
| * can we safely merge with this request? |
| */ |
| int elv_rq_merge_ok(struct request *rq, struct bio *bio) |
| { |
| if (!rq_mergeable(rq)) |
| return 0; |
| |
| /* |
| * Don't merge file system requests and discard requests |
| */ |
| if ((bio->bi_rw & REQ_DISCARD) != (rq->bio->bi_rw & REQ_DISCARD)) |
| return 0; |
| |
| /* |
| * Don't merge discard requests and secure discard requests |
| */ |
| if ((bio->bi_rw & REQ_SECURE) != (rq->bio->bi_rw & REQ_SECURE)) |
| return 0; |
| |
| /* |
| * different data direction or already started, don't merge |
| */ |
| if (bio_data_dir(bio) != rq_data_dir(rq)) |
| return 0; |
| |
| /* |
| * must be same device and not a special request |
| */ |
| if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special) |
| return 0; |
| |
| /* |
| * only merge integrity protected bio into ditto rq |
| */ |
| if (bio_integrity(bio) != blk_integrity_rq(rq)) |
| return 0; |
| |
| if (!elv_iosched_allow_merge(rq, bio)) |
| return 0; |
| |
| return 1; |
| } |
| EXPORT_SYMBOL(elv_rq_merge_ok); |
| |
| int elv_try_merge(struct request *__rq, struct bio *bio) |
| { |
| int ret = ELEVATOR_NO_MERGE; |
| |
| /* |
| * we can merge and sequence is ok, check if it's possible |
| */ |
| if (elv_rq_merge_ok(__rq, bio)) { |
| if (blk_rq_pos(__rq) + blk_rq_sectors(__rq) == bio->bi_sector) |
| ret = ELEVATOR_BACK_MERGE; |
| else if (blk_rq_pos(__rq) - bio_sectors(bio) == bio->bi_sector) |
| ret = ELEVATOR_FRONT_MERGE; |
| } |
| |
| return ret; |
| } |
| |
| static struct elevator_type *elevator_find(const char *name) |
| { |
| struct elevator_type *e; |
| |
| list_for_each_entry(e, &elv_list, list) { |
| if (!strcmp(e->elevator_name, name)) |
| return e; |
| } |
| |
| return NULL; |
| } |
| |
| static void elevator_put(struct elevator_type *e) |
| { |
| module_put(e->elevator_owner); |
| } |
| |
| static struct elevator_type *elevator_get(const char *name) |
| { |
| struct elevator_type *e; |
| |
| spin_lock(&elv_list_lock); |
| |
| e = elevator_find(name); |
| if (!e) { |
| spin_unlock(&elv_list_lock); |
| request_module("%s-iosched", name); |
| spin_lock(&elv_list_lock); |
| e = elevator_find(name); |
| } |
| |
| if (e && !try_module_get(e->elevator_owner)) |
| e = NULL; |
| |
| spin_unlock(&elv_list_lock); |
| |
| return e; |
| } |
| |
| static void *elevator_init_queue(struct request_queue *q, |
| struct elevator_queue *eq) |
| { |
| return eq->ops->elevator_init_fn(q); |
| } |
| |
| static void elevator_attach(struct request_queue *q, struct elevator_queue *eq, |
| void *data) |
| { |
| q->elevator = eq; |
| eq->elevator_data = data; |
| } |
| |
| static char chosen_elevator[ELV_NAME_MAX]; |
| |
| static int __init elevator_setup(char *str) |
| { |
| /* |
| * Be backwards-compatible with previous kernels, so users |
| * won't get the wrong elevator. |
| */ |
| strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); |
| return 1; |
| } |
| |
| __setup("elevator=", elevator_setup); |
| |
| static struct kobj_type elv_ktype; |
| |
| static struct elevator_queue *elevator_alloc(struct request_queue *q, |
| struct elevator_type *e) |
| { |
| struct elevator_queue *eq; |
| int i; |
| |
| eq = kmalloc_node(sizeof(*eq), GFP_KERNEL | __GFP_ZERO, q->node); |
| if (unlikely(!eq)) |
| goto err; |
| |
| eq->ops = &e->ops; |
| eq->elevator_type = e; |
| kobject_init(&eq->kobj, &elv_ktype); |
| mutex_init(&eq->sysfs_lock); |
| |
| eq->hash = kmalloc_node(sizeof(struct hlist_head) * ELV_HASH_ENTRIES, |
| GFP_KERNEL, q->node); |
| if (!eq->hash) |
| goto err; |
| |
| for (i = 0; i < ELV_HASH_ENTRIES; i++) |
| INIT_HLIST_HEAD(&eq->hash[i]); |
| |
| return eq; |
| err: |
| kfree(eq); |
| elevator_put(e); |
| return NULL; |
| } |
| |
| static void elevator_release(struct kobject *kobj) |
| { |
| struct elevator_queue *e; |
| |
| e = container_of(kobj, struct elevator_queue, kobj); |
| elevator_put(e->elevator_type); |
| kfree(e->hash); |
| kfree(e); |
| } |
| |
| int elevator_init(struct request_queue *q, char *name) |
| { |
| struct elevator_type *e = NULL; |
| struct elevator_queue *eq; |
| void *data; |
| |
| if (unlikely(q->elevator)) |
| return 0; |
| |
| INIT_LIST_HEAD(&q->queue_head); |
| q->last_merge = NULL; |
| q->end_sector = 0; |
| q->boundary_rq = NULL; |
| |
| if (name) { |
| e = elevator_get(name); |
| if (!e) |
| return -EINVAL; |
| } |
| |
| if (!e && *chosen_elevator) { |
| e = elevator_get(chosen_elevator); |
| if (!e) |
| printk(KERN_ERR "I/O scheduler %s not found\n", |
| chosen_elevator); |
| } |
| |
| if (!e) { |
| e = elevator_get(CONFIG_DEFAULT_IOSCHED); |
| if (!e) { |
| printk(KERN_ERR |
| "Default I/O scheduler not found. " \ |
| "Using noop.\n"); |
| e = elevator_get("noop"); |
| } |
| } |
| |
| eq = elevator_alloc(q, e); |
| if (!eq) |
| return -ENOMEM; |
| |
| data = elevator_init_queue(q, eq); |
| if (!data) { |
| kobject_put(&eq->kobj); |
| return -ENOMEM; |
| } |
| |
| elevator_attach(q, eq, data); |
| return 0; |
| } |
| EXPORT_SYMBOL(elevator_init); |
| |
| void elevator_exit(struct elevator_queue *e) |
| { |
| mutex_lock(&e->sysfs_lock); |
| if (e->ops->elevator_exit_fn) |
| e->ops->elevator_exit_fn(e); |
| e->ops = NULL; |
| mutex_unlock(&e->sysfs_lock); |
| |
| kobject_put(&e->kobj); |
| } |
| EXPORT_SYMBOL(elevator_exit); |
| |
| static inline void __elv_rqhash_del(struct request *rq) |
| { |
| hlist_del_init(&rq->hash); |
| } |
| |
| static void elv_rqhash_del(struct request_queue *q, struct request *rq) |
| { |
| if (ELV_ON_HASH(rq)) |
| __elv_rqhash_del(rq); |
| } |
| |
| static void elv_rqhash_add(struct request_queue *q, struct request *rq) |
| { |
| struct elevator_queue *e = q->elevator; |
| |
| BUG_ON(ELV_ON_HASH(rq)); |
| hlist_add_head(&rq->hash, &e->hash[ELV_HASH_FN(rq_hash_key(rq))]); |
| } |
| |
| static void elv_rqhash_reposition(struct request_queue *q, struct request *rq) |
| { |
| __elv_rqhash_del(rq); |
| elv_rqhash_add(q, rq); |
| } |
| |
| static struct request *elv_rqhash_find(struct request_queue *q, sector_t offset) |
| { |
| struct elevator_queue *e = q->elevator; |
| struct hlist_head *hash_list = &e->hash[ELV_HASH_FN(offset)]; |
| struct hlist_node *entry, *next; |
| struct request *rq; |
| |
| hlist_for_each_entry_safe(rq, entry, next, hash_list, hash) { |
| 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; |
| } |
| |
| /* |
| * RB-tree support functions for inserting/lookup/removal of requests |
| * in a sorted RB tree. |
| */ |
| void elv_rb_add(struct rb_root *root, struct request *rq) |
| { |
| 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); |
| |
| if (blk_rq_pos(rq) < blk_rq_pos(__rq)) |
| p = &(*p)->rb_left; |
| else if (blk_rq_pos(rq) >= blk_rq_pos(__rq)) |
| p = &(*p)->rb_right; |
| } |
| |
| rb_link_node(&rq->rb_node, parent, p); |
| rb_insert_color(&rq->rb_node, root); |
| } |
| 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); |
| } |
| 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); |
| |
| if (sector < blk_rq_pos(rq)) |
| n = n->rb_left; |
| else if (sector > blk_rq_pos(rq)) |
| n = n->rb_right; |
| else |
| return rq; |
| } |
| |
| return NULL; |
| } |
| EXPORT_SYMBOL(elv_rb_find); |
| |
| /* |
| * Insert rq into dispatch queue of q. Queue lock must be held on |
| * entry. rq is sort instead into the dispatch queue. To be used by |
| * specific elevators. |
| */ |
| void elv_dispatch_sort(struct request_queue *q, struct request *rq) |
| { |
| sector_t boundary; |
| struct list_head *entry; |
| int stop_flags; |
| |
| if (q->last_merge == rq) |
| q->last_merge = NULL; |
| |
| elv_rqhash_del(q, rq); |
| |
| q->nr_sorted--; |
| |
| boundary = q->end_sector; |
| stop_flags = REQ_SOFTBARRIER | REQ_STARTED; |
| list_for_each_prev(entry, &q->queue_head) { |
| struct request *pos = list_entry_rq(entry); |
| |
| if ((rq->cmd_flags & REQ_DISCARD) != |
| (pos->cmd_flags & REQ_DISCARD)) |
| break; |
| if (rq_data_dir(rq) != rq_data_dir(pos)) |
| break; |
| if (pos->cmd_flags & stop_flags) |
| break; |
| if (blk_rq_pos(rq) >= boundary) { |
| if (blk_rq_pos(pos) < boundary) |
| continue; |
| } else { |
| if (blk_rq_pos(pos) >= boundary) |
| break; |
| } |
| if (blk_rq_pos(rq) >= blk_rq_pos(pos)) |
| break; |
| } |
| |
| list_add(&rq->queuelist, entry); |
| } |
| EXPORT_SYMBOL(elv_dispatch_sort); |
| |
| /* |
| * 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. |
| */ |
| 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); |
| } |
| EXPORT_SYMBOL(elv_dispatch_add_tail); |
| |
| int elv_merge(struct request_queue *q, struct request **req, struct bio *bio) |
| { |
| struct elevator_queue *e = q->elevator; |
| struct request *__rq; |
| int ret; |
| |
| /* |
| * 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; |
| |
| /* |
| * First try one-hit cache. |
| */ |
| if (q->last_merge) { |
| ret = elv_try_merge(q->last_merge, bio); |
| if (ret != ELEVATOR_NO_MERGE) { |
| *req = q->last_merge; |
| return ret; |
| } |
| } |
| |
| if (blk_queue_noxmerges(q)) |
| return ELEVATOR_NO_MERGE; |
| |
| /* |
| * 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; |
| } |
| |
| if (e->ops->elevator_merge_fn) |
| return e->ops->elevator_merge_fn(q, req, bio); |
| |
| return ELEVATOR_NO_MERGE; |
| } |
| |
| /* |
| * 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; |
| |
| 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; |
| |
| /* |
| * See if our hash lookup can find a potential backmerge. |
| */ |
| __rq = elv_rqhash_find(q, blk_rq_pos(rq)); |
| if (__rq && blk_attempt_req_merge(q, __rq, rq)) |
| return true; |
| |
| return false; |
| } |
| |
| void elv_merged_request(struct request_queue *q, struct request *rq, int type) |
| { |
| struct elevator_queue *e = q->elevator; |
| |
| if (e->ops->elevator_merged_fn) |
| e->ops->elevator_merged_fn(q, rq, type); |
| |
| 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; |
| const int next_sorted = next->cmd_flags & REQ_SORTED; |
| |
| if (next_sorted && e->ops->elevator_merge_req_fn) |
| e->ops->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 (e->ops->elevator_bio_merged_fn) |
| e->ops->elevator_bio_merged_fn(q, rq, bio); |
| } |
| |
| 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->cmd_flags & REQ_SORTED) |
| elv_deactivate_rq(q, rq); |
| } |
| |
| rq->cmd_flags &= ~REQ_STARTED; |
| |
| __elv_add_request(q, rq, ELEVATOR_INSERT_REQUEUE); |
| } |
| |
| void elv_drain_elevator(struct request_queue *q) |
| { |
| static int printed; |
| |
| lockdep_assert_held(q->queue_lock); |
| |
| while (q->elevator->ops->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->elevator_type->elevator_name, q->nr_sorted); |
| } |
| } |
| |
| void elv_quiesce_start(struct request_queue *q) |
| { |
| if (!q->elevator) |
| return; |
| |
| spin_lock_irq(q->queue_lock); |
| queue_flag_set(QUEUE_FLAG_ELVSWITCH, q); |
| spin_unlock_irq(q->queue_lock); |
| |
| blk_drain_queue(q); |
| } |
| |
| void elv_quiesce_end(struct request_queue *q) |
| { |
| spin_lock_irq(q->queue_lock); |
| queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q); |
| spin_unlock_irq(q->queue_lock); |
| } |
| |
| void __elv_add_request(struct request_queue *q, struct request *rq, int where) |
| { |
| trace_block_rq_insert(q, rq); |
| |
| rq->q = q; |
| |
| if (rq->cmd_flags & REQ_SOFTBARRIER) { |
| /* barriers are scheduling boundary, update end_sector */ |
| if (rq->cmd_type == REQ_TYPE_FS || |
| (rq->cmd_flags & REQ_DISCARD)) { |
| q->end_sector = rq_end_sector(rq); |
| q->boundary_rq = rq; |
| } |
| } else if (!(rq->cmd_flags & REQ_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->cmd_flags |= REQ_SOFTBARRIER; |
| list_add(&rq->queuelist, &q->queue_head); |
| break; |
| |
| case ELEVATOR_INSERT_BACK: |
| rq->cmd_flags |= REQ_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(rq->cmd_type != REQ_TYPE_FS && |
| !(rq->cmd_flags & REQ_DISCARD)); |
| rq->cmd_flags |= REQ_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->ops->elevator_add_req_fn(q, rq); |
| break; |
| |
| case ELEVATOR_INSERT_FLUSH: |
| rq->cmd_flags |= REQ_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->ops->elevator_latter_req_fn) |
| return e->ops->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->ops->elevator_former_req_fn) |
| return e->ops->elevator_former_req_fn(q, rq); |
| return NULL; |
| } |
| |
| int elv_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) |
| { |
| struct elevator_queue *e = q->elevator; |
| |
| if (e->ops->elevator_set_req_fn) |
| return e->ops->elevator_set_req_fn(q, rq, gfp_mask); |
| |
| rq->elevator_private[0] = NULL; |
| return 0; |
| } |
| |
| void elv_put_request(struct request_queue *q, struct request *rq) |
| { |
| struct elevator_queue *e = q->elevator; |
| |
| if (e->ops->elevator_put_req_fn) |
| e->ops->elevator_put_req_fn(rq); |
| } |
| |
| int elv_may_queue(struct request_queue *q, int rw) |
| { |
| struct elevator_queue *e = q->elevator; |
| |
| if (e->ops->elevator_may_queue_fn) |
| return e->ops->elevator_may_queue_fn(q, rw); |
| |
| return ELV_MQUEUE_MAY; |
| } |
| |
| void elv_abort_queue(struct request_queue *q) |
| { |
| struct request *rq; |
| |
| blk_abort_flushes(q); |
| |
| while (!list_empty(&q->queue_head)) { |
| rq = list_entry_rq(q->queue_head.next); |
| rq->cmd_flags |= REQ_QUIET; |
| trace_block_rq_abort(q, rq); |
| /* |
| * Mark this request as started so we don't trigger |
| * any debug logic in the end I/O path. |
| */ |
| blk_start_request(rq); |
| __blk_end_request_all(rq, -EIO); |
| } |
| } |
| EXPORT_SYMBOL(elv_abort_queue); |
| |
| void elv_completed_request(struct request_queue *q, struct request *rq) |
| { |
| struct elevator_queue *e = q->elevator; |
| |
| /* |
| * request is released from the driver, io must be done |
| */ |
| if (blk_account_rq(rq)) { |
| q->in_flight[rq_is_sync(rq)]--; |
| if ((rq->cmd_flags & REQ_SORTED) && |
| e->ops->elevator_completed_req_fn) |
| e->ops->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->ops ? 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->ops ? 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->elevator_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; |
| } |
| return error; |
| } |
| EXPORT_SYMBOL(elv_register_queue); |
| |
| static void __elv_unregister_queue(struct elevator_queue *e) |
| { |
| kobject_uevent(&e->kobj, KOBJ_REMOVE); |
| kobject_del(&e->kobj); |
| e->registered = 0; |
| } |
| |
| void elv_unregister_queue(struct request_queue *q) |
| { |
| if (q) |
| __elv_unregister_queue(q->elevator); |
| } |
| EXPORT_SYMBOL(elv_unregister_queue); |
| |
| void elv_register(struct elevator_type *e) |
| { |
| char *def = ""; |
| |
| spin_lock(&elv_list_lock); |
| BUG_ON(elevator_find(e->elevator_name)); |
| list_add_tail(&e->list, &elv_list); |
| spin_unlock(&elv_list_lock); |
| |
| 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); |
| } |
| EXPORT_SYMBOL_GPL(elv_register); |
| |
| void elv_unregister(struct elevator_type *e) |
| { |
| struct task_struct *g, *p; |
| |
| /* |
| * Iterate every thread in the process to remove the io contexts. |
| */ |
| if (e->ops.trim) { |
| read_lock(&tasklist_lock); |
| do_each_thread(g, p) { |
| task_lock(p); |
| if (p->io_context) |
| e->ops.trim(p->io_context); |
| task_unlock(p); |
| } while_each_thread(g, p); |
| read_unlock(&tasklist_lock); |
| } |
| |
| spin_lock(&elv_list_lock); |
| list_del_init(&e->list); |
| spin_unlock(&elv_list_lock); |
| } |
| 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_elevator, *e; |
| void *data; |
| int err; |
| |
| /* |
| * Allocate new elevator |
| */ |
| e = elevator_alloc(q, new_e); |
| if (!e) |
| return -ENOMEM; |
| |
| data = elevator_init_queue(q, e); |
| if (!data) { |
| kobject_put(&e->kobj); |
| return -ENOMEM; |
| } |
| |
| /* |
| * Turn on BYPASS and drain all requests w/ elevator private data |
| */ |
| elv_quiesce_start(q); |
| |
| /* |
| * Remember old elevator. |
| */ |
| old_elevator = q->elevator; |
| |
| /* |
| * attach and start new elevator |
| */ |
| spin_lock_irq(q->queue_lock); |
| elevator_attach(q, e, data); |
| spin_unlock_irq(q->queue_lock); |
| |
| if (old_elevator->registered) { |
| __elv_unregister_queue(old_elevator); |
| |
| err = elv_register_queue(q); |
| if (err) |
| goto fail_register; |
| } |
| |
| /* |
| * finally exit old elevator and turn off BYPASS. |
| */ |
| elevator_exit(old_elevator); |
| elv_quiesce_end(q); |
| |
| blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name); |
| |
| return 0; |
| |
| fail_register: |
| /* |
| * switch failed, exit the new io scheduler and reattach the old |
| * one again (along with re-adding the sysfs dir) |
| */ |
| elevator_exit(e); |
| q->elevator = old_elevator; |
| elv_register_queue(q); |
| elv_quiesce_end(q); |
| |
| return err; |
| } |
| |
| /* |
| * Switch this queue to the given IO scheduler. |
| */ |
| int elevator_change(struct request_queue *q, const char *name) |
| { |
| char elevator_name[ELV_NAME_MAX]; |
| struct elevator_type *e; |
| |
| if (!q->elevator) |
| return -ENXIO; |
| |
| strlcpy(elevator_name, name, sizeof(elevator_name)); |
| e = elevator_get(strstrip(elevator_name)); |
| if (!e) { |
| printk(KERN_ERR "elevator: type %s not found\n", elevator_name); |
| return -EINVAL; |
| } |
| |
| if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) { |
| elevator_put(e); |
| return 0; |
| } |
| |
| 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\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; |
| struct elevator_type *__e; |
| int len = 0; |
| |
| if (!q->elevator || !blk_queue_stackable(q)) |
| return sprintf(name, "none\n"); |
| |
| elv = e->elevator_type; |
| |
| spin_lock(&elv_list_lock); |
| list_for_each_entry(__e, &elv_list, list) { |
| 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); |
| } |
| spin_unlock(&elv_list_lock); |
| |
| 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); |