Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 1 | /* |
| 2 | * Functions related to io context handling |
| 3 | */ |
| 4 | #include <linux/kernel.h> |
| 5 | #include <linux/module.h> |
| 6 | #include <linux/init.h> |
| 7 | #include <linux/bio.h> |
| 8 | #include <linux/blkdev.h> |
Tejun Heo | 5a0e3ad | 2010-03-24 17:04:11 +0900 | [diff] [blame] | 9 | #include <linux/slab.h> |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 10 | |
| 11 | #include "blk.h" |
| 12 | |
| 13 | /* |
| 14 | * For io context allocations |
| 15 | */ |
| 16 | static struct kmem_cache *iocontext_cachep; |
| 17 | |
Tejun Heo | 6e736be | 2011-12-14 00:33:38 +0100 | [diff] [blame] | 18 | /** |
| 19 | * get_io_context - increment reference count to io_context |
| 20 | * @ioc: io_context to get |
| 21 | * |
| 22 | * Increment reference count to @ioc. |
| 23 | */ |
| 24 | void get_io_context(struct io_context *ioc) |
| 25 | { |
| 26 | BUG_ON(atomic_long_read(&ioc->refcount) <= 0); |
| 27 | atomic_long_inc(&ioc->refcount); |
| 28 | } |
| 29 | EXPORT_SYMBOL(get_io_context); |
| 30 | |
Tejun Heo | 7e5a879 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 31 | static void icq_free_icq_rcu(struct rcu_head *head) |
| 32 | { |
| 33 | struct io_cq *icq = container_of(head, struct io_cq, __rcu_head); |
| 34 | |
| 35 | kmem_cache_free(icq->__rcu_icq_cache, icq); |
| 36 | } |
| 37 | |
Tejun Heo | 621032a | 2012-02-15 09:45:53 +0100 | [diff] [blame] | 38 | /* Exit an icq. Called with both ioc and q locked. */ |
Tejun Heo | 7e5a879 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 39 | static void ioc_exit_icq(struct io_cq *icq) |
| 40 | { |
Tejun Heo | 621032a | 2012-02-15 09:45:53 +0100 | [diff] [blame] | 41 | struct elevator_type *et = icq->q->elevator->type; |
| 42 | |
| 43 | if (icq->flags & ICQ_EXITED) |
| 44 | return; |
| 45 | |
| 46 | if (et->ops.elevator_exit_icq_fn) |
| 47 | et->ops.elevator_exit_icq_fn(icq); |
| 48 | |
| 49 | icq->flags |= ICQ_EXITED; |
| 50 | } |
| 51 | |
| 52 | /* Release an icq. Called with both ioc and q locked. */ |
| 53 | static void ioc_destroy_icq(struct io_cq *icq) |
| 54 | { |
Tejun Heo | 7e5a879 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 55 | struct io_context *ioc = icq->ioc; |
| 56 | struct request_queue *q = icq->q; |
| 57 | struct elevator_type *et = q->elevator->type; |
| 58 | |
| 59 | lockdep_assert_held(&ioc->lock); |
| 60 | lockdep_assert_held(q->queue_lock); |
| 61 | |
| 62 | radix_tree_delete(&ioc->icq_tree, icq->q->id); |
| 63 | hlist_del_init(&icq->ioc_node); |
| 64 | list_del_init(&icq->q_node); |
| 65 | |
| 66 | /* |
| 67 | * Both setting lookup hint to and clearing it from @icq are done |
| 68 | * under queue_lock. If it's not pointing to @icq now, it never |
| 69 | * will. Hint assignment itself can race safely. |
| 70 | */ |
Paul E. McKenney | ec6c676 | 2014-02-17 13:35:57 -0800 | [diff] [blame] | 71 | if (rcu_access_pointer(ioc->icq_hint) == icq) |
Tejun Heo | 7e5a879 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 72 | rcu_assign_pointer(ioc->icq_hint, NULL); |
| 73 | |
Tejun Heo | 621032a | 2012-02-15 09:45:53 +0100 | [diff] [blame] | 74 | ioc_exit_icq(icq); |
Tejun Heo | 7e5a879 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 75 | |
| 76 | /* |
| 77 | * @icq->q might have gone away by the time RCU callback runs |
| 78 | * making it impossible to determine icq_cache. Record it in @icq. |
| 79 | */ |
| 80 | icq->__rcu_icq_cache = et->icq_cache; |
| 81 | call_rcu(&icq->__rcu_head, icq_free_icq_rcu); |
| 82 | } |
| 83 | |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 84 | /* |
| 85 | * Slow path for ioc release in put_io_context(). Performs double-lock |
Tejun Heo | c586980 | 2011-12-14 00:33:41 +0100 | [diff] [blame] | 86 | * dancing to unlink all icq's and then frees ioc. |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 87 | */ |
| 88 | static void ioc_release_fn(struct work_struct *work) |
| 89 | { |
| 90 | struct io_context *ioc = container_of(work, struct io_context, |
| 91 | release_work); |
Tejun Heo | d8c66c5 | 2012-02-11 12:37:25 +0100 | [diff] [blame] | 92 | unsigned long flags; |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 93 | |
Tejun Heo | d8c66c5 | 2012-02-11 12:37:25 +0100 | [diff] [blame] | 94 | /* |
| 95 | * Exiting icq may call into put_io_context() through elevator |
| 96 | * which will trigger lockdep warning. The ioc's are guaranteed to |
| 97 | * be different, use a different locking subclass here. Use |
| 98 | * irqsave variant as there's no spin_lock_irq_nested(). |
| 99 | */ |
| 100 | spin_lock_irqsave_nested(&ioc->lock, flags, 1); |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 101 | |
Tejun Heo | c586980 | 2011-12-14 00:33:41 +0100 | [diff] [blame] | 102 | while (!hlist_empty(&ioc->icq_list)) { |
| 103 | struct io_cq *icq = hlist_entry(ioc->icq_list.first, |
| 104 | struct io_cq, ioc_node); |
Tejun Heo | 2274b02 | 2012-02-15 09:45:52 +0100 | [diff] [blame] | 105 | struct request_queue *q = icq->q; |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 106 | |
Tejun Heo | 2274b02 | 2012-02-15 09:45:52 +0100 | [diff] [blame] | 107 | if (spin_trylock(q->queue_lock)) { |
Tejun Heo | 621032a | 2012-02-15 09:45:53 +0100 | [diff] [blame] | 108 | ioc_destroy_icq(icq); |
Tejun Heo | 2274b02 | 2012-02-15 09:45:52 +0100 | [diff] [blame] | 109 | spin_unlock(q->queue_lock); |
| 110 | } else { |
| 111 | spin_unlock_irqrestore(&ioc->lock, flags); |
| 112 | cpu_relax(); |
| 113 | spin_lock_irqsave_nested(&ioc->lock, flags, 1); |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 114 | } |
Jens Axboe | ffc4e75 | 2008-02-19 10:02:29 +0100 | [diff] [blame] | 115 | } |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 116 | |
Tejun Heo | 2274b02 | 2012-02-15 09:45:52 +0100 | [diff] [blame] | 117 | spin_unlock_irqrestore(&ioc->lock, flags); |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 118 | |
| 119 | kmem_cache_free(iocontext_cachep, ioc); |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 120 | } |
| 121 | |
Tejun Heo | 42ec57a | 2011-12-14 00:33:37 +0100 | [diff] [blame] | 122 | /** |
| 123 | * put_io_context - put a reference of io_context |
| 124 | * @ioc: io_context to put |
| 125 | * |
| 126 | * Decrement reference count of @ioc and release it if the count reaches |
Tejun Heo | 11a3122 | 2012-02-07 07:51:30 +0100 | [diff] [blame] | 127 | * zero. |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 128 | */ |
Tejun Heo | 11a3122 | 2012-02-07 07:51:30 +0100 | [diff] [blame] | 129 | void put_io_context(struct io_context *ioc) |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 130 | { |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 131 | unsigned long flags; |
Xiaotian Feng | ff8c147 | 2012-03-14 15:34:48 +0100 | [diff] [blame] | 132 | bool free_ioc = false; |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 133 | |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 134 | if (ioc == NULL) |
Tejun Heo | 42ec57a | 2011-12-14 00:33:37 +0100 | [diff] [blame] | 135 | return; |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 136 | |
Tejun Heo | 42ec57a | 2011-12-14 00:33:37 +0100 | [diff] [blame] | 137 | BUG_ON(atomic_long_read(&ioc->refcount) <= 0); |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 138 | |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 139 | /* |
Tejun Heo | 11a3122 | 2012-02-07 07:51:30 +0100 | [diff] [blame] | 140 | * Releasing ioc requires reverse order double locking and we may |
| 141 | * already be holding a queue_lock. Do it asynchronously from wq. |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 142 | */ |
Tejun Heo | 11a3122 | 2012-02-07 07:51:30 +0100 | [diff] [blame] | 143 | if (atomic_long_dec_and_test(&ioc->refcount)) { |
| 144 | spin_lock_irqsave(&ioc->lock, flags); |
| 145 | if (!hlist_empty(&ioc->icq_list)) |
Viresh Kumar | 695588f | 2013-04-24 17:12:56 +0530 | [diff] [blame] | 146 | queue_work(system_power_efficient_wq, |
| 147 | &ioc->release_work); |
Xiaotian Feng | ff8c147 | 2012-03-14 15:34:48 +0100 | [diff] [blame] | 148 | else |
| 149 | free_ioc = true; |
Tejun Heo | 11a3122 | 2012-02-07 07:51:30 +0100 | [diff] [blame] | 150 | spin_unlock_irqrestore(&ioc->lock, flags); |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 151 | } |
Xiaotian Feng | ff8c147 | 2012-03-14 15:34:48 +0100 | [diff] [blame] | 152 | |
| 153 | if (free_ioc) |
| 154 | kmem_cache_free(iocontext_cachep, ioc); |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 155 | } |
| 156 | EXPORT_SYMBOL(put_io_context); |
| 157 | |
Tejun Heo | f6e8d01 | 2012-03-05 13:15:26 -0800 | [diff] [blame] | 158 | /** |
| 159 | * put_io_context_active - put active reference on ioc |
| 160 | * @ioc: ioc of interest |
| 161 | * |
| 162 | * Undo get_io_context_active(). If active reference reaches zero after |
| 163 | * put, @ioc can never issue further IOs and ioscheds are notified. |
| 164 | */ |
| 165 | void put_io_context_active(struct io_context *ioc) |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 166 | { |
Tejun Heo | 621032a | 2012-02-15 09:45:53 +0100 | [diff] [blame] | 167 | unsigned long flags; |
Tejun Heo | f6e8d01 | 2012-03-05 13:15:26 -0800 | [diff] [blame] | 168 | struct io_cq *icq; |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 169 | |
Tejun Heo | f6e8d01 | 2012-03-05 13:15:26 -0800 | [diff] [blame] | 170 | if (!atomic_dec_and_test(&ioc->active_ref)) { |
Tejun Heo | 621032a | 2012-02-15 09:45:53 +0100 | [diff] [blame] | 171 | put_io_context(ioc); |
| 172 | return; |
| 173 | } |
| 174 | |
| 175 | /* |
| 176 | * Need ioc lock to walk icq_list and q lock to exit icq. Perform |
| 177 | * reverse double locking. Read comment in ioc_release_fn() for |
| 178 | * explanation on the nested locking annotation. |
| 179 | */ |
| 180 | retry: |
| 181 | spin_lock_irqsave_nested(&ioc->lock, flags, 1); |
Sasha Levin | b67bfe0 | 2013-02-27 17:06:00 -0800 | [diff] [blame] | 182 | hlist_for_each_entry(icq, &ioc->icq_list, ioc_node) { |
Tejun Heo | 621032a | 2012-02-15 09:45:53 +0100 | [diff] [blame] | 183 | if (icq->flags & ICQ_EXITED) |
| 184 | continue; |
| 185 | if (spin_trylock(icq->q->queue_lock)) { |
| 186 | ioc_exit_icq(icq); |
| 187 | spin_unlock(icq->q->queue_lock); |
| 188 | } else { |
| 189 | spin_unlock_irqrestore(&ioc->lock, flags); |
| 190 | cpu_relax(); |
| 191 | goto retry; |
| 192 | } |
| 193 | } |
| 194 | spin_unlock_irqrestore(&ioc->lock, flags); |
| 195 | |
Tejun Heo | 11a3122 | 2012-02-07 07:51:30 +0100 | [diff] [blame] | 196 | put_io_context(ioc); |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 197 | } |
| 198 | |
Tejun Heo | f6e8d01 | 2012-03-05 13:15:26 -0800 | [diff] [blame] | 199 | /* Called by the exiting task */ |
| 200 | void exit_io_context(struct task_struct *task) |
| 201 | { |
| 202 | struct io_context *ioc; |
| 203 | |
| 204 | task_lock(task); |
| 205 | ioc = task->io_context; |
| 206 | task->io_context = NULL; |
| 207 | task_unlock(task); |
| 208 | |
| 209 | atomic_dec(&ioc->nr_tasks); |
| 210 | put_io_context_active(ioc); |
| 211 | } |
| 212 | |
Tejun Heo | 7e5a879 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 213 | /** |
| 214 | * ioc_clear_queue - break any ioc association with the specified queue |
| 215 | * @q: request_queue being cleared |
| 216 | * |
| 217 | * Walk @q->icq_list and exit all io_cq's. Must be called with @q locked. |
| 218 | */ |
| 219 | void ioc_clear_queue(struct request_queue *q) |
| 220 | { |
| 221 | lockdep_assert_held(q->queue_lock); |
| 222 | |
| 223 | while (!list_empty(&q->icq_list)) { |
| 224 | struct io_cq *icq = list_entry(q->icq_list.next, |
| 225 | struct io_cq, q_node); |
| 226 | struct io_context *ioc = icq->ioc; |
| 227 | |
| 228 | spin_lock(&ioc->lock); |
Tejun Heo | 621032a | 2012-02-15 09:45:53 +0100 | [diff] [blame] | 229 | ioc_destroy_icq(icq); |
Tejun Heo | 7e5a879 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 230 | spin_unlock(&ioc->lock); |
| 231 | } |
| 232 | } |
| 233 | |
Tejun Heo | 24acfc3 | 2012-03-05 13:15:24 -0800 | [diff] [blame] | 234 | int create_task_io_context(struct task_struct *task, gfp_t gfp_flags, int node) |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 235 | { |
Paul Bolle | df41565 | 2011-06-06 05:11:34 +0200 | [diff] [blame] | 236 | struct io_context *ioc; |
Eric Dumazet | 3c9c708 | 2012-05-31 13:39:05 +0200 | [diff] [blame] | 237 | int ret; |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 238 | |
Tejun Heo | 42ec57a | 2011-12-14 00:33:37 +0100 | [diff] [blame] | 239 | ioc = kmem_cache_alloc_node(iocontext_cachep, gfp_flags | __GFP_ZERO, |
| 240 | node); |
| 241 | if (unlikely(!ioc)) |
Tejun Heo | 24acfc3 | 2012-03-05 13:15:24 -0800 | [diff] [blame] | 242 | return -ENOMEM; |
Tejun Heo | 42ec57a | 2011-12-14 00:33:37 +0100 | [diff] [blame] | 243 | |
| 244 | /* initialize */ |
| 245 | atomic_long_set(&ioc->refcount, 1); |
Olof Johansson | 4638a83 | 2012-08-01 12:17:27 +0200 | [diff] [blame] | 246 | atomic_set(&ioc->nr_tasks, 1); |
Tejun Heo | f6e8d01 | 2012-03-05 13:15:26 -0800 | [diff] [blame] | 247 | atomic_set(&ioc->active_ref, 1); |
Tejun Heo | 42ec57a | 2011-12-14 00:33:37 +0100 | [diff] [blame] | 248 | spin_lock_init(&ioc->lock); |
Tejun Heo | c586980 | 2011-12-14 00:33:41 +0100 | [diff] [blame] | 249 | INIT_RADIX_TREE(&ioc->icq_tree, GFP_ATOMIC | __GFP_HIGH); |
| 250 | INIT_HLIST_HEAD(&ioc->icq_list); |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 251 | INIT_WORK(&ioc->release_work, ioc_release_fn); |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 252 | |
Tejun Heo | fd63836 | 2011-12-25 14:29:14 +0100 | [diff] [blame] | 253 | /* |
| 254 | * Try to install. ioc shouldn't be installed if someone else |
| 255 | * already did or @task, which isn't %current, is exiting. Note |
| 256 | * that we need to allow ioc creation on exiting %current as exit |
| 257 | * path may issue IOs from e.g. exit_files(). The exit path is |
| 258 | * responsible for not issuing IO after exit_io_context(). |
| 259 | */ |
Tejun Heo | 6e736be | 2011-12-14 00:33:38 +0100 | [diff] [blame] | 260 | task_lock(task); |
Tejun Heo | fd63836 | 2011-12-25 14:29:14 +0100 | [diff] [blame] | 261 | if (!task->io_context && |
| 262 | (task == current || !(task->flags & PF_EXITING))) |
Tejun Heo | 6e736be | 2011-12-14 00:33:38 +0100 | [diff] [blame] | 263 | task->io_context = ioc; |
Tejun Heo | f2dbd76 | 2011-12-14 00:33:40 +0100 | [diff] [blame] | 264 | else |
Tejun Heo | 6e736be | 2011-12-14 00:33:38 +0100 | [diff] [blame] | 265 | kmem_cache_free(iocontext_cachep, ioc); |
Eric Dumazet | 3c9c708 | 2012-05-31 13:39:05 +0200 | [diff] [blame] | 266 | |
| 267 | ret = task->io_context ? 0 : -EBUSY; |
| 268 | |
Tejun Heo | 6e736be | 2011-12-14 00:33:38 +0100 | [diff] [blame] | 269 | task_unlock(task); |
Tejun Heo | 24acfc3 | 2012-03-05 13:15:24 -0800 | [diff] [blame] | 270 | |
Eric Dumazet | 3c9c708 | 2012-05-31 13:39:05 +0200 | [diff] [blame] | 271 | return ret; |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 272 | } |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 273 | |
Tejun Heo | 6e736be | 2011-12-14 00:33:38 +0100 | [diff] [blame] | 274 | /** |
| 275 | * get_task_io_context - get io_context of a task |
| 276 | * @task: task of interest |
| 277 | * @gfp_flags: allocation flags, used if allocation is necessary |
| 278 | * @node: allocation node, used if allocation is necessary |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 279 | * |
Tejun Heo | 6e736be | 2011-12-14 00:33:38 +0100 | [diff] [blame] | 280 | * Return io_context of @task. If it doesn't exist, it is created with |
| 281 | * @gfp_flags and @node. The returned io_context has its reference count |
| 282 | * incremented. |
| 283 | * |
| 284 | * This function always goes through task_lock() and it's better to use |
Tejun Heo | f2dbd76 | 2011-12-14 00:33:40 +0100 | [diff] [blame] | 285 | * %current->io_context + get_io_context() for %current. |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 286 | */ |
Tejun Heo | 6e736be | 2011-12-14 00:33:38 +0100 | [diff] [blame] | 287 | struct io_context *get_task_io_context(struct task_struct *task, |
| 288 | gfp_t gfp_flags, int node) |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 289 | { |
Tejun Heo | 6e736be | 2011-12-14 00:33:38 +0100 | [diff] [blame] | 290 | struct io_context *ioc; |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 291 | |
Mel Gorman | d0164ad | 2015-11-06 16:28:21 -0800 | [diff] [blame] | 292 | might_sleep_if(gfpflags_allow_blocking(gfp_flags)); |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 293 | |
Tejun Heo | f2dbd76 | 2011-12-14 00:33:40 +0100 | [diff] [blame] | 294 | do { |
| 295 | task_lock(task); |
| 296 | ioc = task->io_context; |
| 297 | if (likely(ioc)) { |
| 298 | get_io_context(ioc); |
| 299 | task_unlock(task); |
| 300 | return ioc; |
| 301 | } |
Tejun Heo | 6e736be | 2011-12-14 00:33:38 +0100 | [diff] [blame] | 302 | task_unlock(task); |
Tejun Heo | 24acfc3 | 2012-03-05 13:15:24 -0800 | [diff] [blame] | 303 | } while (!create_task_io_context(task, gfp_flags, node)); |
Tejun Heo | 6e736be | 2011-12-14 00:33:38 +0100 | [diff] [blame] | 304 | |
Tejun Heo | f2dbd76 | 2011-12-14 00:33:40 +0100 | [diff] [blame] | 305 | return NULL; |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 306 | } |
Tejun Heo | 6e736be | 2011-12-14 00:33:38 +0100 | [diff] [blame] | 307 | EXPORT_SYMBOL(get_task_io_context); |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 308 | |
Tejun Heo | 47fdd4c | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 309 | /** |
| 310 | * ioc_lookup_icq - lookup io_cq from ioc |
| 311 | * @ioc: the associated io_context |
| 312 | * @q: the associated request_queue |
| 313 | * |
| 314 | * Look up io_cq associated with @ioc - @q pair from @ioc. Must be called |
| 315 | * with @q->queue_lock held. |
| 316 | */ |
| 317 | struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q) |
| 318 | { |
| 319 | struct io_cq *icq; |
| 320 | |
| 321 | lockdep_assert_held(q->queue_lock); |
| 322 | |
| 323 | /* |
| 324 | * icq's are indexed from @ioc using radix tree and hint pointer, |
| 325 | * both of which are protected with RCU. All removals are done |
| 326 | * holding both q and ioc locks, and we're holding q lock - if we |
| 327 | * find a icq which points to us, it's guaranteed to be valid. |
| 328 | */ |
| 329 | rcu_read_lock(); |
| 330 | icq = rcu_dereference(ioc->icq_hint); |
| 331 | if (icq && icq->q == q) |
| 332 | goto out; |
| 333 | |
| 334 | icq = radix_tree_lookup(&ioc->icq_tree, q->id); |
| 335 | if (icq && icq->q == q) |
| 336 | rcu_assign_pointer(ioc->icq_hint, icq); /* allowed to race */ |
| 337 | else |
| 338 | icq = NULL; |
| 339 | out: |
| 340 | rcu_read_unlock(); |
| 341 | return icq; |
| 342 | } |
| 343 | EXPORT_SYMBOL(ioc_lookup_icq); |
| 344 | |
Tejun Heo | f1f8cc9 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 345 | /** |
| 346 | * ioc_create_icq - create and link io_cq |
Tejun Heo | 24acfc3 | 2012-03-05 13:15:24 -0800 | [diff] [blame] | 347 | * @ioc: io_context of interest |
Tejun Heo | f1f8cc9 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 348 | * @q: request_queue of interest |
| 349 | * @gfp_mask: allocation mask |
| 350 | * |
Tejun Heo | 24acfc3 | 2012-03-05 13:15:24 -0800 | [diff] [blame] | 351 | * Make sure io_cq linking @ioc and @q exists. If icq doesn't exist, they |
| 352 | * will be created using @gfp_mask. |
Tejun Heo | f1f8cc9 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 353 | * |
| 354 | * The caller is responsible for ensuring @ioc won't go away and @q is |
| 355 | * alive and will stay alive until this function returns. |
| 356 | */ |
Tejun Heo | 24acfc3 | 2012-03-05 13:15:24 -0800 | [diff] [blame] | 357 | struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q, |
| 358 | gfp_t gfp_mask) |
Tejun Heo | f1f8cc9 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 359 | { |
| 360 | struct elevator_type *et = q->elevator->type; |
Tejun Heo | f1f8cc9 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 361 | struct io_cq *icq; |
| 362 | |
| 363 | /* allocate stuff */ |
Tejun Heo | f1f8cc9 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 364 | icq = kmem_cache_alloc_node(et->icq_cache, gfp_mask | __GFP_ZERO, |
| 365 | q->node); |
| 366 | if (!icq) |
| 367 | return NULL; |
| 368 | |
Jan Kara | 5e4c0d97 | 2013-09-11 14:26:05 -0700 | [diff] [blame] | 369 | if (radix_tree_maybe_preload(gfp_mask) < 0) { |
Tejun Heo | f1f8cc9 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 370 | kmem_cache_free(et->icq_cache, icq); |
| 371 | return NULL; |
| 372 | } |
| 373 | |
| 374 | icq->ioc = ioc; |
| 375 | icq->q = q; |
| 376 | INIT_LIST_HEAD(&icq->q_node); |
| 377 | INIT_HLIST_NODE(&icq->ioc_node); |
| 378 | |
| 379 | /* lock both q and ioc and try to link @icq */ |
| 380 | spin_lock_irq(q->queue_lock); |
| 381 | spin_lock(&ioc->lock); |
| 382 | |
| 383 | if (likely(!radix_tree_insert(&ioc->icq_tree, q->id, icq))) { |
| 384 | hlist_add_head(&icq->ioc_node, &ioc->icq_list); |
| 385 | list_add(&icq->q_node, &q->icq_list); |
| 386 | if (et->ops.elevator_init_icq_fn) |
| 387 | et->ops.elevator_init_icq_fn(icq); |
| 388 | } else { |
| 389 | kmem_cache_free(et->icq_cache, icq); |
| 390 | icq = ioc_lookup_icq(ioc, q); |
| 391 | if (!icq) |
| 392 | printk(KERN_ERR "cfq: icq link failed!\n"); |
| 393 | } |
| 394 | |
| 395 | spin_unlock(&ioc->lock); |
| 396 | spin_unlock_irq(q->queue_lock); |
| 397 | radix_tree_preload_end(); |
| 398 | return icq; |
| 399 | } |
| 400 | |
Adrian Bunk | 1334159 | 2008-02-18 13:45:53 +0100 | [diff] [blame] | 401 | static int __init blk_ioc_init(void) |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 402 | { |
| 403 | iocontext_cachep = kmem_cache_create("blkdev_ioc", |
| 404 | sizeof(struct io_context), 0, SLAB_PANIC, NULL); |
| 405 | return 0; |
| 406 | } |
| 407 | subsys_initcall(blk_ioc_init); |