diff options
Diffstat (limited to 'block/elevator.c')
-rw-r--r-- | block/elevator.c | 315 |
1 files changed, 263 insertions, 52 deletions
diff --git a/block/elevator.c b/block/elevator.c index 9b72dc7..487dd3d 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -3,7 +3,7 @@ * * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE * - * 30042000 Jens Axboe <axboe@suse.de> : + * 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: @@ -33,6 +33,7 @@ #include <linux/compiler.h> #include <linux/delay.h> #include <linux/blktrace_api.h> +#include <linux/hash.h> #include <asm/uaccess.h> @@ -40,6 +41,16 @@ 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) ((rq)->sector + (rq)->nr_sectors) +#define ELV_ON_HASH(rq) (!hlist_unhashed(&(rq)->hash)) + +/* * can we safely merge with this request? */ inline int elv_rq_merge_ok(struct request *rq, struct bio *bio) @@ -56,8 +67,7 @@ inline int elv_rq_merge_ok(struct request *rq, struct bio *bio) /* * same device and no special stuff set, merge is ok */ - if (rq->rq_disk == bio->bi_bdev->bd_disk && - !rq->waiting && !rq->special) + if (rq->rq_disk == bio->bi_bdev->bd_disk && !rq->special) return 1; return 0; @@ -151,27 +161,44 @@ __setup("elevator=", elevator_setup); static struct kobj_type elv_ktype; -static elevator_t *elevator_alloc(struct elevator_type *e) -{ - elevator_t *eq = kmalloc(sizeof(elevator_t), GFP_KERNEL); - if (eq) { - memset(eq, 0, sizeof(*eq)); - eq->ops = &e->ops; - eq->elevator_type = e; - kobject_init(&eq->kobj); - snprintf(eq->kobj.name, KOBJ_NAME_LEN, "%s", "iosched"); - eq->kobj.ktype = &elv_ktype; - mutex_init(&eq->sysfs_lock); - } else { - elevator_put(e); - } +static elevator_t *elevator_alloc(request_queue_t *q, struct elevator_type *e) +{ + elevator_t *eq; + int i; + + eq = kmalloc_node(sizeof(elevator_t), GFP_KERNEL, q->node); + if (unlikely(!eq)) + goto err; + + memset(eq, 0, sizeof(*eq)); + eq->ops = &e->ops; + eq->elevator_type = e; + kobject_init(&eq->kobj); + snprintf(eq->kobj.name, KOBJ_NAME_LEN, "%s", "iosched"); + eq->kobj.ktype = &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) { elevator_t *e = container_of(kobj, elevator_t, kobj); + elevator_put(e->elevator_type); + kfree(e->hash); kfree(e); } @@ -198,7 +225,7 @@ int elevator_init(request_queue_t *q, char *name) e = elevator_get("noop"); } - eq = elevator_alloc(e); + eq = elevator_alloc(q, e); if (!eq) return -ENOMEM; @@ -212,6 +239,8 @@ int elevator_init(request_queue_t *q, char *name) return ret; } +EXPORT_SYMBOL(elevator_init); + void elevator_exit(elevator_t *e) { mutex_lock(&e->sysfs_lock); @@ -223,10 +252,118 @@ void elevator_exit(elevator_t *e) 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(request_queue_t *q, struct request *rq) +{ + if (ELV_ON_HASH(rq)) + __elv_rqhash_del(rq); +} + +static void elv_rqhash_add(request_queue_t *q, struct request *rq) +{ + elevator_t *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(request_queue_t *q, struct request *rq) +{ + __elv_rqhash_del(rq); + elv_rqhash_add(q, rq); +} + +static struct request *elv_rqhash_find(request_queue_t *q, sector_t offset) +{ + elevator_t *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. + */ +struct request *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 (rq->sector < __rq->sector) + p = &(*p)->rb_left; + else if (rq->sector > __rq->sector) + p = &(*p)->rb_right; + else + return __rq; + } + + rb_link_node(&rq->rb_node, parent, p); + rb_insert_color(&rq->rb_node, root); + return NULL; +} + +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 < rq->sector) + n = n->rb_left; + else if (sector > rq->sector) + 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. If sort != 0, rq is sort-inserted; otherwise, rq will be - * appended to the dispatch queue. To be used by specific elevators. + * entry. rq is sort insted into the dispatch queue. To be used by + * specific elevators. */ void elv_dispatch_sort(request_queue_t *q, struct request *rq) { @@ -235,6 +372,9 @@ void elv_dispatch_sort(request_queue_t *q, struct request *rq) if (q->last_merge == rq) q->last_merge = NULL; + + elv_rqhash_del(q, rq); + q->nr_sorted--; boundary = q->end_sector; @@ -242,7 +382,7 @@ void elv_dispatch_sort(request_queue_t *q, struct request *rq) list_for_each_prev(entry, &q->queue_head) { struct request *pos = list_entry_rq(entry); - if (pos->flags & (REQ_SOFTBARRIER|REQ_HARDBARRIER|REQ_STARTED)) + if (pos->cmd_flags & (REQ_SOFTBARRIER|REQ_HARDBARRIER|REQ_STARTED)) break; if (rq->sector >= boundary) { if (pos->sector < boundary) @@ -258,11 +398,38 @@ void elv_dispatch_sort(request_queue_t *q, struct request *rq) 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(request_queue_t *q, struct request **req, struct bio *bio) { elevator_t *e = q->elevator; + struct request *__rq; int ret; + /* + * First try one-hit cache. + */ if (q->last_merge) { ret = elv_try_merge(q->last_merge, bio); if (ret != ELEVATOR_NO_MERGE) { @@ -271,18 +438,30 @@ int elv_merge(request_queue_t *q, struct request **req, struct bio *bio) } } + /* + * 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; } -void elv_merged_request(request_queue_t *q, struct request *rq) +void elv_merged_request(request_queue_t *q, struct request *rq, int type) { elevator_t *e = q->elevator; if (e->ops->elevator_merged_fn) - e->ops->elevator_merged_fn(q, rq); + e->ops->elevator_merged_fn(q, rq, type); + + if (type == ELEVATOR_BACK_MERGE) + elv_rqhash_reposition(q, rq); q->last_merge = rq; } @@ -294,8 +473,11 @@ void elv_merge_requests(request_queue_t *q, struct request *rq, if (e->ops->elevator_merge_req_fn) e->ops->elevator_merge_req_fn(q, rq, next); - q->nr_sorted--; + elv_rqhash_reposition(q, rq); + elv_rqhash_del(q, next); + + q->nr_sorted--; q->last_merge = rq; } @@ -313,7 +495,7 @@ void elv_requeue_request(request_queue_t *q, struct request *rq) e->ops->elevator_deactivate_req_fn(q, rq); } - rq->flags &= ~REQ_STARTED; + rq->cmd_flags &= ~REQ_STARTED; elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); } @@ -344,13 +526,13 @@ void elv_insert(request_queue_t *q, struct request *rq, int where) switch (where) { case ELEVATOR_INSERT_FRONT: - rq->flags |= REQ_SOFTBARRIER; + rq->cmd_flags |= REQ_SOFTBARRIER; list_add(&rq->queuelist, &q->queue_head); break; case ELEVATOR_INSERT_BACK: - rq->flags |= REQ_SOFTBARRIER; + rq->cmd_flags |= REQ_SOFTBARRIER; elv_drain_elevator(q); list_add_tail(&rq->queuelist, &q->queue_head); /* @@ -369,10 +551,14 @@ void elv_insert(request_queue_t *q, struct request *rq, int where) case ELEVATOR_INSERT_SORT: BUG_ON(!blk_fs_request(rq)); - rq->flags |= REQ_SORTED; + rq->cmd_flags |= REQ_SORTED; q->nr_sorted++; - if (q->last_merge == NULL && rq_mergeable(rq)) - q->last_merge = rq; + 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 @@ -387,7 +573,7 @@ void elv_insert(request_queue_t *q, struct request *rq, int where) * insertion; otherwise, requests should be requeued * in ordseq order. */ - rq->flags |= REQ_SOFTBARRIER; + rq->cmd_flags |= REQ_SOFTBARRIER; if (q->ordseq == 0) { list_add(&rq->queuelist, &q->queue_head); @@ -429,9 +615,9 @@ void __elv_add_request(request_queue_t *q, struct request *rq, int where, int plug) { if (q->ordcolor) - rq->flags |= REQ_ORDERED_COLOR; + rq->cmd_flags |= REQ_ORDERED_COLOR; - if (rq->flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { + if (rq->cmd_flags & (REQ_SOFTBARRIER | REQ_HARDBARRIER)) { /* * toggle ordered color */ @@ -452,7 +638,7 @@ void __elv_add_request(request_queue_t *q, struct request *rq, int where, q->end_sector = rq_end_sector(rq); q->boundary_rq = rq; } - } else if (!(rq->flags & REQ_ELVPRIV) && where == ELEVATOR_INSERT_SORT) + } else if (!(rq->cmd_flags & REQ_ELVPRIV) && where == ELEVATOR_INSERT_SORT) where = ELEVATOR_INSERT_BACK; if (plug) @@ -461,6 +647,8 @@ void __elv_add_request(request_queue_t *q, struct request *rq, int where, elv_insert(q, rq, where); } +EXPORT_SYMBOL(__elv_add_request); + void elv_add_request(request_queue_t *q, struct request *rq, int where, int plug) { @@ -471,6 +659,8 @@ void elv_add_request(request_queue_t *q, struct request *rq, int where, spin_unlock_irqrestore(q->queue_lock, flags); } +EXPORT_SYMBOL(elv_add_request); + static inline struct request *__elv_next_request(request_queue_t *q) { struct request *rq; @@ -493,7 +683,7 @@ struct request *elv_next_request(request_queue_t *q) int ret; while ((rq = __elv_next_request(q)) != NULL) { - if (!(rq->flags & REQ_STARTED)) { + if (!(rq->cmd_flags & REQ_STARTED)) { elevator_t *e = q->elevator; /* @@ -510,7 +700,7 @@ struct request *elv_next_request(request_queue_t *q) * it, a request that has been delayed should * not be passed by new incoming requests */ - rq->flags |= REQ_STARTED; + rq->cmd_flags |= REQ_STARTED; blk_add_trace_rq(q, rq, BLK_TA_ISSUE); } @@ -519,7 +709,7 @@ struct request *elv_next_request(request_queue_t *q) q->boundary_rq = NULL; } - if ((rq->flags & REQ_DONTPREP) || !q->prep_rq_fn) + if ((rq->cmd_flags & REQ_DONTPREP) || !q->prep_rq_fn) break; ret = q->prep_rq_fn(q, rq); @@ -541,7 +731,7 @@ struct request *elv_next_request(request_queue_t *q) nr_bytes = rq->data_len; blkdev_dequeue_request(rq); - rq->flags |= REQ_QUIET; + rq->cmd_flags |= REQ_QUIET; end_that_request_chunk(rq, 0, nr_bytes); end_that_request_last(rq, 0); } else { @@ -554,9 +744,12 @@ struct request *elv_next_request(request_queue_t *q) return rq; } +EXPORT_SYMBOL(elv_next_request); + void elv_dequeue_request(request_queue_t *q, struct request *rq) { BUG_ON(list_empty(&rq->queuelist)); + BUG_ON(ELV_ON_HASH(rq)); list_del_init(&rq->queuelist); @@ -569,6 +762,8 @@ void elv_dequeue_request(request_queue_t *q, struct request *rq) q->in_flight++; } +EXPORT_SYMBOL(elv_dequeue_request); + int elv_queue_empty(request_queue_t *q) { elevator_t *e = q->elevator; @@ -582,6 +777,8 @@ int elv_queue_empty(request_queue_t *q) return 1; } +EXPORT_SYMBOL(elv_queue_empty); + struct request *elv_latter_request(request_queue_t *q, struct request *rq) { elevator_t *e = q->elevator; @@ -600,13 +797,12 @@ struct request *elv_former_request(request_queue_t *q, struct request *rq) return NULL; } -int elv_set_request(request_queue_t *q, struct request *rq, struct bio *bio, - gfp_t gfp_mask) +int elv_set_request(request_queue_t *q, struct request *rq, gfp_t gfp_mask) { elevator_t *e = q->elevator; if (e->ops->elevator_set_req_fn) - return e->ops->elevator_set_req_fn(q, rq, bio, gfp_mask); + return e->ops->elevator_set_req_fn(q, rq, gfp_mask); rq->elevator_private = NULL; return 0; @@ -620,12 +816,12 @@ void elv_put_request(request_queue_t *q, struct request *rq) e->ops->elevator_put_req_fn(q, rq); } -int elv_may_queue(request_queue_t *q, int rw, struct bio *bio) +int elv_may_queue(request_queue_t *q, int rw) { elevator_t *e = q->elevator; if (e->ops->elevator_may_queue_fn) - return e->ops->elevator_may_queue_fn(q, rw, bio); + return e->ops->elevator_may_queue_fn(q, rw); return ELV_MQUEUE_MAY; } @@ -792,7 +988,7 @@ static int elevator_switch(request_queue_t *q, struct elevator_type *new_e) /* * Allocate new elevator */ - e = elevator_alloc(new_e); + e = elevator_alloc(q, new_e); if (!e) return 0; @@ -908,11 +1104,26 @@ ssize_t elv_iosched_show(request_queue_t *q, char *name) return len; } -EXPORT_SYMBOL(elv_dispatch_sort); -EXPORT_SYMBOL(elv_add_request); -EXPORT_SYMBOL(__elv_add_request); -EXPORT_SYMBOL(elv_next_request); -EXPORT_SYMBOL(elv_dequeue_request); -EXPORT_SYMBOL(elv_queue_empty); -EXPORT_SYMBOL(elevator_exit); -EXPORT_SYMBOL(elevator_init); +struct request *elv_rb_former_request(request_queue_t *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(request_queue_t *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); |