X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=drivers%2Fblock%2Felevator.c;h=35f4079b04d66c539d00396225f918cbd79c5030;hb=6a77f38946aaee1cd85eeec6cf4229b204c15071;hp=35c9385ac13345431c93233d48247b6b388b599f;hpb=87fc8d1bb10cd459024a742c6a10961fefcef18f;p=linux-2.6.git diff --git a/drivers/block/elevator.c b/drivers/block/elevator.c index 35c9385ac..35f4079b0 100644 --- a/drivers/block/elevator.c +++ b/drivers/block/elevator.c @@ -37,6 +37,9 @@ #include +static DEFINE_SPINLOCK(elv_list_lock); +static LIST_HEAD(elv_list); + /* * can we safely merge with this request? */ @@ -60,6 +63,7 @@ inline int elv_rq_merge_ok(struct request *rq, struct bio *bio) return 0; } +EXPORT_SYMBOL(elv_rq_merge_ok); inline int elv_try_merge(struct request *__rq, struct bio *bio) { @@ -77,6 +81,7 @@ inline int elv_try_merge(struct request *__rq, struct bio *bio) return ret; } +EXPORT_SYMBOL(elv_try_merge); inline int elv_try_last_merge(request_queue_t *q, struct bio *bio) { @@ -85,31 +90,134 @@ inline int elv_try_last_merge(request_queue_t *q, struct bio *bio) return ELEVATOR_NO_MERGE; } +EXPORT_SYMBOL(elv_try_last_merge); -/* - * general block -> elevator interface starts here - */ -int elevator_init(request_queue_t *q, elevator_t *type) +struct elevator_type *elevator_find(const char *name) { - elevator_t *e = &q->elevator; + struct elevator_type *e = NULL; + struct list_head *entry; + + spin_lock_irq(&elv_list_lock); + list_for_each(entry, &elv_list) { + struct elevator_type *__e; - memcpy(e, type, sizeof(*e)); + __e = list_entry(entry, struct elevator_type, list); + + if (!strcmp(__e->elevator_name, name)) { + e = __e; + break; + } + } + spin_unlock_irq(&elv_list_lock); + + return e; +} + +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 = elevator_find(name); + + if (!e) + return NULL; + if (!try_module_get(e->elevator_owner)) + return NULL; + + return e; +} + +static int elevator_attach(request_queue_t *q, struct elevator_type *e, + struct elevator_queue *eq) +{ + int ret = 0; + + memset(eq, 0, sizeof(*eq)); + eq->ops = &e->ops; + eq->elevator_type = e; INIT_LIST_HEAD(&q->queue_head); q->last_merge = NULL; + q->elevator = eq; + + if (eq->ops->elevator_init_fn) + ret = eq->ops->elevator_init_fn(q, eq); + + return ret; +} - if (e->elevator_init_fn) - return e->elevator_init_fn(q, e); +static char chosen_elevator[16]; +static void elevator_setup_default(void) +{ + /* + * check if default is set and exists + */ + if (chosen_elevator[0] && elevator_find(chosen_elevator)) + return; + +#if defined(CONFIG_IOSCHED_AS) + strcpy(chosen_elevator, "anticipatory"); +#elif defined(CONFIG_IOSCHED_DEADLINE) + strcpy(chosen_elevator, "deadline"); +#elif defined(CONFIG_IOSCHED_CFQ) + strcpy(chosen_elevator, "cfq"); +#elif defined(CONFIG_IOSCHED_NOOP) + strcpy(chosen_elevator, "noop"); +#else +#error "You must build at least 1 IO scheduler into the kernel" +#endif +} + +static int __init elevator_setup(char *str) +{ + strncpy(chosen_elevator, str, sizeof(chosen_elevator) - 1); return 0; } -void elevator_exit(request_queue_t *q) +__setup("elevator=", elevator_setup); + +int elevator_init(request_queue_t *q, char *name) +{ + struct elevator_type *e = NULL; + struct elevator_queue *eq; + int ret = 0; + + elevator_setup_default(); + + if (!name) + name = chosen_elevator; + + e = elevator_get(name); + if (!e) + return -EINVAL; + + eq = kmalloc(sizeof(struct elevator_queue), GFP_KERNEL); + if (!eq) { + elevator_put(e->elevator_type); + return -ENOMEM; + } + + ret = elevator_attach(q, e, eq); + if (ret) { + kfree(eq); + elevator_put(e->elevator_type); + } + + return ret; +} + +void elevator_exit(elevator_t *e) { - elevator_t *e = &q->elevator; + if (e->ops->elevator_exit_fn) + e->ops->elevator_exit_fn(e); - if (e->elevator_exit_fn) - e->elevator_exit_fn(q, e); + elevator_put(e->elevator_type); + e->elevator_type = NULL; + kfree(e); } int elevator_global_init(void) @@ -119,32 +227,32 @@ int elevator_global_init(void) int elv_merge(request_queue_t *q, struct request **req, struct bio *bio) { - elevator_t *e = &q->elevator; + elevator_t *e = q->elevator; - if (e->elevator_merge_fn) - return e->elevator_merge_fn(q, req, bio); + 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) { - elevator_t *e = &q->elevator; + elevator_t *e = q->elevator; - if (e->elevator_merged_fn) - e->elevator_merged_fn(q, rq); + if (e->ops->elevator_merged_fn) + e->ops->elevator_merged_fn(q, rq); } void elv_merge_requests(request_queue_t *q, struct request *rq, struct request *next) { - elevator_t *e = &q->elevator; + elevator_t *e = q->elevator; if (q->last_merge == next) q->last_merge = NULL; - if (e->elevator_merge_req_fn) - e->elevator_merge_req_fn(q, rq, next); + if (e->ops->elevator_merge_req_fn) + e->ops->elevator_merge_req_fn(q, rq, next); } void elv_requeue_request(request_queue_t *q, struct request *rq) @@ -160,8 +268,8 @@ void elv_requeue_request(request_queue_t *q, struct request *rq) * if iosched has an explicit requeue hook, then use that. otherwise * just put the request at the front of the queue */ - if (q->elevator.elevator_requeue_req_fn) - q->elevator.elevator_requeue_req_fn(q, rq); + if (q->elevator->ops->elevator_requeue_req_fn) + q->elevator->ops->elevator_requeue_req_fn(q, rq); else __elv_add_request(q, rq, ELEVATOR_INSERT_FRONT, 0); } @@ -180,15 +288,24 @@ void __elv_add_request(request_queue_t *q, struct request *rq, int where, blk_plug_device(q); rq->q = q; - q->elevator.elevator_add_req_fn(q, rq, where); - if (blk_queue_plugged(q)) { - int nrq = q->rq.count[READ] + q->rq.count[WRITE] - q->in_flight; + if (!test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags)) { + q->elevator->ops->elevator_add_req_fn(q, rq, where); - if (nrq == q->unplug_thresh) - __generic_unplug_device(q); - } + if (blk_queue_plugged(q)) { + int nrq = q->rq.count[READ] + q->rq.count[WRITE] + - q->in_flight; + if (nrq == q->unplug_thresh) + __generic_unplug_device(q); + } + } else + /* + * if drain is set, store the request "locally". when the drain + * is finished, the requests will be handed ordered to the io + * scheduler + */ + list_add_tail(&rq->queuelist, &q->drain_list); } void elv_add_request(request_queue_t *q, struct request *rq, int where, @@ -203,7 +320,7 @@ void elv_add_request(request_queue_t *q, struct request *rq, int where, static inline struct request *__elv_next_request(request_queue_t *q) { - return q->elevator.elevator_next_req_fn(q); + return q->elevator->ops->elevator_next_req_fn(q); } struct request *elv_next_request(request_queue_t *q) @@ -242,7 +359,8 @@ struct request *elv_next_request(request_queue_t *q) end_that_request_chunk(rq, 0, nr_bytes); end_that_request_last(rq); } else { - printk("%s: bad return=%d\n", __FUNCTION__, ret); + printk(KERN_ERR "%s: bad return=%d\n", __FUNCTION__, + ret); break; } } @@ -252,7 +370,7 @@ struct request *elv_next_request(request_queue_t *q) void elv_remove_request(request_queue_t *q, struct request *rq) { - elevator_t *e = &q->elevator; + elevator_t *e = q->elevator; /* * the time frame between a request being removed from the lists @@ -274,16 +392,16 @@ void elv_remove_request(request_queue_t *q, struct request *rq) if (rq == q->last_merge) q->last_merge = NULL; - if (e->elevator_remove_req_fn) - e->elevator_remove_req_fn(q, rq); + if (e->ops->elevator_remove_req_fn) + e->ops->elevator_remove_req_fn(q, rq); } int elv_queue_empty(request_queue_t *q) { - elevator_t *e = &q->elevator; + elevator_t *e = q->elevator; - if (e->elevator_queue_empty_fn) - return e->elevator_queue_empty_fn(q); + if (e->ops->elevator_queue_empty_fn) + return e->ops->elevator_queue_empty_fn(q); return list_empty(&q->queue_head); } @@ -292,10 +410,10 @@ struct request *elv_latter_request(request_queue_t *q, struct request *rq) { struct list_head *next; - elevator_t *e = &q->elevator; + elevator_t *e = q->elevator; - if (e->elevator_latter_req_fn) - return e->elevator_latter_req_fn(q, rq); + if (e->ops->elevator_latter_req_fn) + return e->ops->elevator_latter_req_fn(q, rq); next = rq->queuelist.next; if (next != &q->queue_head && next != &rq->queuelist) @@ -308,10 +426,10 @@ struct request *elv_former_request(request_queue_t *q, struct request *rq) { struct list_head *prev; - elevator_t *e = &q->elevator; + elevator_t *e = q->elevator; - if (e->elevator_former_req_fn) - return e->elevator_former_req_fn(q, rq); + if (e->ops->elevator_former_req_fn) + return e->ops->elevator_former_req_fn(q, rq); prev = rq->queuelist.prev; if (prev != &q->queue_head && prev != &rq->queuelist) @@ -322,10 +440,10 @@ struct request *elv_former_request(request_queue_t *q, struct request *rq) int elv_set_request(request_queue_t *q, struct request *rq, int gfp_mask) { - elevator_t *e = &q->elevator; + elevator_t *e = q->elevator; - if (e->elevator_set_req_fn) - return e->elevator_set_req_fn(q, rq, gfp_mask); + if (e->ops->elevator_set_req_fn) + return e->ops->elevator_set_req_fn(q, rq, gfp_mask); rq->elevator_private = NULL; return 0; @@ -333,25 +451,25 @@ int elv_set_request(request_queue_t *q, struct request *rq, int gfp_mask) void elv_put_request(request_queue_t *q, struct request *rq) { - elevator_t *e = &q->elevator; + elevator_t *e = q->elevator; - if (e->elevator_put_req_fn) - e->elevator_put_req_fn(q, rq); + if (e->ops->elevator_put_req_fn) + e->ops->elevator_put_req_fn(q, rq); } int elv_may_queue(request_queue_t *q, int rw) { - elevator_t *e = &q->elevator; + elevator_t *e = q->elevator; - if (e->elevator_may_queue_fn) - return e->elevator_may_queue_fn(q, rw); + if (e->ops->elevator_may_queue_fn) + return e->ops->elevator_may_queue_fn(q, rw); - return 0; + return ELV_MQUEUE_MAY; } void elv_completed_request(request_queue_t *q, struct request *rq) { - elevator_t *e = &q->elevator; + elevator_t *e = q->elevator; /* * request is released from the driver, io must be done @@ -359,22 +477,20 @@ void elv_completed_request(request_queue_t *q, struct request *rq) if (blk_account_rq(rq)) q->in_flight--; - if (e->elevator_completed_req_fn) - e->elevator_completed_req_fn(q, rq); + if (e->ops->elevator_completed_req_fn) + e->ops->elevator_completed_req_fn(q, rq); } int elv_register_queue(struct request_queue *q) { - elevator_t *e; - - e = &q->elevator; + elevator_t *e = q->elevator; e->kobj.parent = kobject_get(&q->kobj); if (!e->kobj.parent) return -EBUSY; snprintf(e->kobj.name, KOBJ_NAME_LEN, "%s", "iosched"); - e->kobj.ktype = e->elevator_ktype; + e->kobj.ktype = e->elevator_type->elevator_ktype; return kobject_register(&e->kobj); } @@ -382,12 +498,160 @@ int elv_register_queue(struct request_queue *q) void elv_unregister_queue(struct request_queue *q) { if (q) { - elevator_t * e = &q->elevator; + elevator_t *e = q->elevator; kobject_unregister(&e->kobj); kobject_put(&q->kobj); } } +int elv_register(struct elevator_type *e) +{ + if (elevator_find(e->elevator_name)) + BUG(); + + spin_lock_irq(&elv_list_lock); + list_add_tail(&e->list, &elv_list); + spin_unlock_irq(&elv_list_lock); + + printk(KERN_INFO "io scheduler %s registered", e->elevator_name); + if (!strcmp(e->elevator_name, chosen_elevator)) + printk(" (default)"); + printk("\n"); + return 0; +} +EXPORT_SYMBOL_GPL(elv_register); + +void elv_unregister(struct elevator_type *e) +{ + spin_lock_irq(&elv_list_lock); + list_del_init(&e->list); + spin_unlock_irq(&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. we also do an intermediate + * switch to noop to ensure safety with stack-allocated requests, since they + * don't originate from the block layer allocator. noop is safe here, because + * it never needs to touch the elevator itself for completion events. DRAIN + * flags will make sure we don't touch it for additions either. + */ +static void elevator_switch(request_queue_t *q, struct elevator_type *new_e) +{ + elevator_t *e = kmalloc(sizeof(elevator_t), GFP_KERNEL); + struct elevator_type *noop_elevator = NULL; + elevator_t *old_elevator; + + if (!e) + goto error; + + /* + * first step, drain requests from the block freelist + */ + blk_wait_queue_drained(q, 0); + + /* + * unregister old elevator data + */ + elv_unregister_queue(q); + old_elevator = q->elevator; + + /* + * next step, switch to noop since it uses no private rq structures + * and doesn't allocate any memory for anything. then wait for any + * non-fs requests in-flight + */ + noop_elevator = elevator_get("noop"); + spin_lock_irq(q->queue_lock); + elevator_attach(q, noop_elevator, e); + spin_unlock_irq(q->queue_lock); + + blk_wait_queue_drained(q, 1); + + /* + * attach and start new elevator + */ + if (elevator_attach(q, new_e, e)) + goto fail; + + if (elv_register_queue(q)) + goto fail_register; + + /* + * finally exit old elevator and start queue again + */ + elevator_exit(old_elevator); + blk_finish_queue_drain(q); + elevator_put(noop_elevator); + return; + +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); +fail: + q->elevator = old_elevator; + elv_register_queue(q); + blk_finish_queue_drain(q); +error: + if (noop_elevator) + elevator_put(noop_elevator); + elevator_put(new_e); + printk(KERN_ERR "elevator: switch to %s failed\n",new_e->elevator_name); +} + +ssize_t elv_iosched_store(request_queue_t *q, const char *name, size_t count) +{ + char elevator_name[ELV_NAME_MAX]; + struct elevator_type *e; + + memset(elevator_name, 0, sizeof(elevator_name)); + strncpy(elevator_name, name, sizeof(elevator_name)); + + if (elevator_name[strlen(elevator_name) - 1] == '\n') + elevator_name[strlen(elevator_name) - 1] = '\0'; + + e = elevator_get(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)) + return count; + + elevator_switch(q, e); + return count; +} + +ssize_t elv_iosched_show(request_queue_t *q, char *name) +{ + elevator_t *e = q->elevator; + struct elevator_type *elv = e->elevator_type; + struct list_head *entry; + int len = 0; + + spin_lock_irq(q->queue_lock); + list_for_each(entry, &elv_list) { + struct elevator_type *__e; + + __e = list_entry(entry, struct elevator_type, 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_irq(q->queue_lock); + + len += sprintf(len+name, "\n"); + return len; +} + module_init(elevator_global_init); EXPORT_SYMBOL(elv_add_request);