diff options
| -rw-r--r-- | block/blk-ioc.c | 76 | ||||
| -rw-r--r-- | block/blk-sysfs.c | 6 | ||||
| -rw-r--r-- | block/blk.h | 1 | ||||
| -rw-r--r-- | block/cfq-iosched.c | 47 | ||||
| -rw-r--r-- | block/elevator.c | 3 | ||||
| -rw-r--r-- | include/linux/elevator.h | 5 | ||||
| -rw-r--r-- | include/linux/iocontext.h | 20 |
7 files changed, 97 insertions, 61 deletions
diff --git a/block/blk-ioc.c b/block/blk-ioc.c index 87ecc98b8ad..0910a5584d3 100644 --- a/block/blk-ioc.c +++ b/block/blk-ioc.c @@ -44,6 +44,51 @@ EXPORT_SYMBOL(get_io_context); #define ioc_release_depth_dec(q) do { } while (0) #endif +static void icq_free_icq_rcu(struct rcu_head *head) +{ + struct io_cq *icq = container_of(head, struct io_cq, __rcu_head); + + kmem_cache_free(icq->__rcu_icq_cache, icq); +} + +/* + * Exit and free an icq. Called with both ioc and q locked. + */ +static void ioc_exit_icq(struct io_cq *icq) +{ + struct io_context *ioc = icq->ioc; + struct request_queue *q = icq->q; + struct elevator_type *et = q->elevator->type; + + lockdep_assert_held(&ioc->lock); + lockdep_assert_held(q->queue_lock); + + radix_tree_delete(&ioc->icq_tree, icq->q->id); + hlist_del_init(&icq->ioc_node); + list_del_init(&icq->q_node); + + /* + * Both setting lookup hint to and clearing it from @icq are done + * under queue_lock. If it's not pointing to @icq now, it never + * will. Hint assignment itself can race safely. + */ + if (rcu_dereference_raw(ioc->icq_hint) == icq) + rcu_assign_pointer(ioc->icq_hint, NULL); + + if (et->ops.elevator_exit_icq_fn) { + ioc_release_depth_inc(q); + et->ops.elevator_exit_icq_fn(icq); + ioc_release_depth_dec(q); + } + + /* + * @icq->q might have gone away by the time RCU callback runs + * making it impossible to determine icq_cache. Record it in @icq. + */ + icq->__rcu_icq_cache = et->icq_cache; + call_rcu(&icq->__rcu_head, icq_free_icq_rcu); +} + /* * Slow path for ioc release in put_io_context(). Performs double-lock * dancing to unlink all icq's and then frees ioc. @@ -87,10 +132,7 @@ static void ioc_release_fn(struct work_struct *work) spin_lock(&ioc->lock); continue; } - ioc_release_depth_inc(this_q); - icq->exit(icq); - icq->release(icq); - ioc_release_depth_dec(this_q); + ioc_exit_icq(icq); } if (last_q) { @@ -167,10 +209,7 @@ void put_io_context(struct io_context *ioc, struct request_queue *locked_q) last_q = this_q; continue; } - ioc_release_depth_inc(this_q); - icq->exit(icq); - icq->release(icq); - ioc_release_depth_dec(this_q); + ioc_exit_icq(icq); } if (last_q && last_q != locked_q) @@ -203,6 +242,27 @@ void exit_io_context(struct task_struct *task) put_io_context(ioc, NULL); } +/** + * ioc_clear_queue - break any ioc association with the specified queue + * @q: request_queue being cleared + * + * Walk @q->icq_list and exit all io_cq's. Must be called with @q locked. + */ +void ioc_clear_queue(struct request_queue *q) +{ + lockdep_assert_held(q->queue_lock); + + while (!list_empty(&q->icq_list)) { + struct io_cq *icq = list_entry(q->icq_list.next, + struct io_cq, q_node); + struct io_context *ioc = icq->ioc; + + spin_lock(&ioc->lock); + ioc_exit_icq(icq); + spin_unlock(&ioc->lock); + } +} + void create_io_context_slowpath(struct task_struct *task, gfp_t gfp_flags, int node) { diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index 5b4b4ab5e78..cf150011d80 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -479,8 +479,12 @@ static void blk_release_queue(struct kobject *kobj) blk_sync_queue(q); - if (q->elevator) + if (q->elevator) { + spin_lock_irq(q->queue_lock); + ioc_clear_queue(q); + spin_unlock_irq(q->queue_lock); elevator_exit(q->elevator); + } blk_throtl_exit(q); diff --git a/block/blk.h b/block/blk.h index 3c510a4b505..ed4d9bf2ab1 100644 --- a/block/blk.h +++ b/block/blk.h @@ -200,6 +200,7 @@ static inline int blk_do_io_stat(struct request *rq) */ void get_io_context(struct io_context *ioc); struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q); +void ioc_clear_queue(struct request_queue *q); void create_io_context_slowpath(struct task_struct *task, gfp_t gfp_mask, int node); diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 06e59abcb57..f6d31555149 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -2674,26 +2674,6 @@ static void cfq_put_queue(struct cfq_queue *cfqq) cfq_put_cfqg(cfqg); } -static void cfq_icq_free_rcu(struct rcu_head *head) -{ - kmem_cache_free(cfq_icq_pool, - icq_to_cic(container_of(head, struct io_cq, rcu_head))); -} - -static void cfq_icq_free(struct io_cq *icq) -{ - call_rcu(&icq->rcu_head, cfq_icq_free_rcu); -} - -static void cfq_release_icq(struct io_cq *icq) -{ - struct io_context *ioc = icq->ioc; - - radix_tree_delete(&ioc->icq_tree, icq->q->id); - hlist_del(&icq->ioc_node); - cfq_icq_free(icq); -} - static void cfq_put_cooperator(struct cfq_queue *cfqq) { struct cfq_queue *__cfqq, *next; @@ -2731,17 +2711,6 @@ static void cfq_exit_icq(struct io_cq *icq) { struct cfq_io_cq *cic = icq_to_cic(icq); struct cfq_data *cfqd = cic_to_cfqd(cic); - struct io_context *ioc = icq->ioc; - - list_del_init(&icq->q_node); - - /* - * Both setting lookup hint to and clearing it from @icq are done - * under queue_lock. If it's not pointing to @icq now, it never - * will. Hint assignment itself can race safely. - */ - if (rcu_dereference_raw(ioc->icq_hint) == icq) - rcu_assign_pointer(ioc->icq_hint, NULL); if (cic->cfqq[BLK_RW_ASYNC]) { cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]); @@ -2764,8 +2733,6 @@ static struct cfq_io_cq *cfq_alloc_cic(struct cfq_data *cfqd, gfp_t gfp_mask) cic->ttime.last_end_request = jiffies; INIT_LIST_HEAD(&cic->icq.q_node); INIT_HLIST_NODE(&cic->icq.ioc_node); - cic->icq.exit = cfq_exit_icq; - cic->icq.release = cfq_release_icq; } return cic; @@ -3034,7 +3001,7 @@ out: if (ret) printk(KERN_ERR "cfq: icq link failed!\n"); if (icq) - cfq_icq_free(icq); + kmem_cache_free(cfq_icq_pool, icq); return ret; } @@ -3774,17 +3741,6 @@ static void cfq_exit_queue(struct elevator_queue *e) if (cfqd->active_queue) __cfq_slice_expired(cfqd, cfqd->active_queue, 0); - while (!list_empty(&q->icq_list)) { - struct io_cq *icq = list_entry(q->icq_list.next, - struct io_cq, q_node); - struct io_context *ioc = icq->ioc; - - spin_lock(&ioc->lock); - cfq_exit_icq(icq); - cfq_release_icq(icq); - spin_unlock(&ioc->lock); - } - cfq_put_async_queues(cfqd); cfq_release_cfq_groups(cfqd); @@ -4019,6 +3975,7 @@ static struct elevator_type iosched_cfq = { .elevator_completed_req_fn = cfq_completed_request, .elevator_former_req_fn = elv_rb_former_request, .elevator_latter_req_fn = elv_rb_latter_request, + .elevator_exit_icq_fn = cfq_exit_icq, .elevator_set_req_fn = cfq_set_request, .elevator_put_req_fn = cfq_put_request, .elevator_may_queue_fn = cfq_may_queue, diff --git a/block/elevator.c b/block/elevator.c index cca049fb45c..91e18f8af9b 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -979,8 +979,9 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e) goto fail_register; } - /* done, replace the old one with new one and turn off BYPASS */ + /* done, clear io_cq's, switch elevators and turn off BYPASS */ spin_lock_irq(q->queue_lock); + ioc_clear_queue(q); old_elevator = q->elevator; q->elevator = e; spin_unlock_irq(q->queue_lock); diff --git a/include/linux/elevator.h b/include/linux/elevator.h index d3d3e28cbfd..06e4dd56871 100644 --- a/include/linux/elevator.h +++ b/include/linux/elevator.h @@ -5,6 +5,8 @@ #ifdef CONFIG_BLOCK +struct io_cq; + typedef int (elevator_merge_fn) (struct request_queue *, struct request **, struct bio *); @@ -24,6 +26,7 @@ typedef struct request *(elevator_request_list_fn) (struct request_queue *, stru typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *); typedef int (elevator_may_queue_fn) (struct request_queue *, int); +typedef void (elevator_exit_icq_fn) (struct io_cq *); typedef int (elevator_set_req_fn) (struct request_queue *, struct request *, gfp_t); typedef void (elevator_put_req_fn) (struct request *); typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *); @@ -56,6 +59,8 @@ struct elevator_ops elevator_request_list_fn *elevator_former_req_fn; elevator_request_list_fn *elevator_latter_req_fn; + elevator_exit_icq_fn *elevator_exit_icq_fn; + elevator_set_req_fn *elevator_set_req_fn; elevator_put_req_fn *elevator_put_req_fn; diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h index d15ca6591f9..ac390a34c0e 100644 --- a/include/linux/iocontext.h +++ b/include/linux/iocontext.h @@ -14,14 +14,22 @@ struct io_cq { struct request_queue *q; struct io_context *ioc; - struct list_head q_node; - struct hlist_node ioc_node; + /* + * q_node and ioc_node link io_cq through icq_list of q and ioc + * respectively. Both fields are unused once ioc_exit_icq() is + * called and shared with __rcu_icq_cache and __rcu_head which are + * used for RCU free of io_cq. + */ + union { + struct list_head q_node; + struct kmem_cache *__rcu_icq_cache; + }; + union { + struct hlist_node ioc_node; + struct rcu_head __rcu_head; + }; unsigned long changed; - struct rcu_head rcu_head; - - void (*exit)(struct io_cq *); - void (*release)(struct io_cq *); }; /* |