blob: 57299f860d41ebb9d09414fe976def0e5ab6ac51 [file] [log] [blame]
Greg Kroah-Hartmanb2441312017-11-01 15:07:57 +01001// SPDX-License-Identifier: GPL-2.0
Jens Axboe86db1e22008-01-29 14:53:40 +01002/*
3 * Functions related to io context handling
4 */
5#include <linux/kernel.h>
6#include <linux/module.h>
7#include <linux/init.h>
8#include <linux/bio.h>
9#include <linux/blkdev.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090010#include <linux/slab.h>
Ingo Molnarf719ff9b2017-02-06 10:57:33 +010011#include <linux/sched/task.h>
Jens Axboe86db1e22008-01-29 14:53:40 +010012
13#include "blk.h"
14
15/*
16 * For io context allocations
17 */
18static struct kmem_cache *iocontext_cachep;
19
Tejun Heo6e736be2011-12-14 00:33:38 +010020/**
21 * get_io_context - increment reference count to io_context
22 * @ioc: io_context to get
23 *
24 * Increment reference count to @ioc.
25 */
26void get_io_context(struct io_context *ioc)
27{
28 BUG_ON(atomic_long_read(&ioc->refcount) <= 0);
29 atomic_long_inc(&ioc->refcount);
30}
Tejun Heo6e736be2011-12-14 00:33:38 +010031
Tejun Heo7e5a8792011-12-14 00:33:42 +010032static void icq_free_icq_rcu(struct rcu_head *head)
33{
34 struct io_cq *icq = container_of(head, struct io_cq, __rcu_head);
35
36 kmem_cache_free(icq->__rcu_icq_cache, icq);
37}
38
Omar Sandoval3d492c22017-02-10 10:32:34 -080039/*
Jens Axboe7b36a712017-03-02 13:59:08 -070040 * Exit an icq. Called with ioc locked for blk-mq, and with both ioc
41 * and queue locked for legacy.
Omar Sandoval3d492c22017-02-10 10:32:34 -080042 */
Tejun Heo7e5a8792011-12-14 00:33:42 +010043static void ioc_exit_icq(struct io_cq *icq)
44{
Tejun Heo621032a2012-02-15 09:45:53 +010045 struct elevator_type *et = icq->q->elevator->type;
46
47 if (icq->flags & ICQ_EXITED)
48 return;
49
Jens Axboef9cd4bf2018-11-01 16:41:41 -060050 if (et->ops.exit_icq)
51 et->ops.exit_icq(icq);
Tejun Heo621032a2012-02-15 09:45:53 +010052
53 icq->flags |= ICQ_EXITED;
54}
55
Jens Axboe7b36a712017-03-02 13:59:08 -070056/*
57 * Release an icq. Called with ioc locked for blk-mq, and with both ioc
58 * and queue locked for legacy.
59 */
Tejun Heo621032a2012-02-15 09:45:53 +010060static void ioc_destroy_icq(struct io_cq *icq)
61{
Tejun Heo7e5a8792011-12-14 00:33:42 +010062 struct io_context *ioc = icq->ioc;
63 struct request_queue *q = icq->q;
64 struct elevator_type *et = q->elevator->type;
65
66 lockdep_assert_held(&ioc->lock);
Tejun Heo7e5a8792011-12-14 00:33:42 +010067
68 radix_tree_delete(&ioc->icq_tree, icq->q->id);
69 hlist_del_init(&icq->ioc_node);
70 list_del_init(&icq->q_node);
71
72 /*
73 * Both setting lookup hint to and clearing it from @icq are done
74 * under queue_lock. If it's not pointing to @icq now, it never
75 * will. Hint assignment itself can race safely.
76 */
Paul E. McKenneyec6c676a2014-02-17 13:35:57 -080077 if (rcu_access_pointer(ioc->icq_hint) == icq)
Tejun Heo7e5a8792011-12-14 00:33:42 +010078 rcu_assign_pointer(ioc->icq_hint, NULL);
79
Tejun Heo621032a2012-02-15 09:45:53 +010080 ioc_exit_icq(icq);
Tejun Heo7e5a8792011-12-14 00:33:42 +010081
82 /*
83 * @icq->q might have gone away by the time RCU callback runs
84 * making it impossible to determine icq_cache. Record it in @icq.
85 */
86 icq->__rcu_icq_cache = et->icq_cache;
Sahitya Tummala30a2da72020-03-11 16:07:50 +053087 icq->flags |= ICQ_DESTROYED;
Tejun Heo7e5a8792011-12-14 00:33:42 +010088 call_rcu(&icq->__rcu_head, icq_free_icq_rcu);
89}
90
Tejun Heob2efa052011-12-14 00:33:39 +010091/*
92 * Slow path for ioc release in put_io_context(). Performs double-lock
Tejun Heoc5869802011-12-14 00:33:41 +010093 * dancing to unlink all icq's and then frees ioc.
Tejun Heob2efa052011-12-14 00:33:39 +010094 */
95static void ioc_release_fn(struct work_struct *work)
96{
97 struct io_context *ioc = container_of(work, struct io_context,
98 release_work);
John Ognessa43f0852020-06-19 17:23:17 +020699 spin_lock_irq(&ioc->lock);
Tejun Heob2efa052011-12-14 00:33:39 +0100100
Tejun Heoc5869802011-12-14 00:33:41 +0100101 while (!hlist_empty(&ioc->icq_list)) {
102 struct io_cq *icq = hlist_entry(ioc->icq_list.first,
103 struct io_cq, ioc_node);
Tejun Heo2274b022012-02-15 09:45:52 +0100104 struct request_queue *q = icq->q;
Tejun Heob2efa052011-12-14 00:33:39 +0100105
Christoph Hellwig0d945c12018-11-15 12:17:28 -0700106 if (spin_trylock(&q->queue_lock)) {
Tejun Heo621032a2012-02-15 09:45:53 +0100107 ioc_destroy_icq(icq);
Christoph Hellwig0d945c12018-11-15 12:17:28 -0700108 spin_unlock(&q->queue_lock);
Tejun Heo2274b022012-02-15 09:45:52 +0100109 } else {
John Ognessab96bba2020-06-19 17:23:18 +0206110 /* Make sure q and icq cannot be freed. */
111 rcu_read_lock();
112
113 /* Re-acquire the locks in the correct order. */
114 spin_unlock(&ioc->lock);
115 spin_lock(&q->queue_lock);
116 spin_lock(&ioc->lock);
117
118 /*
119 * The icq may have been destroyed when the ioc lock
120 * was released.
121 */
122 if (!(icq->flags & ICQ_DESTROYED))
123 ioc_destroy_icq(icq);
124
125 spin_unlock(&q->queue_lock);
126 rcu_read_unlock();
Tejun Heob2efa052011-12-14 00:33:39 +0100127 }
Jens Axboeffc4e752008-02-19 10:02:29 +0100128 }
Tejun Heob2efa052011-12-14 00:33:39 +0100129
John Ognessa43f0852020-06-19 17:23:17 +0206130 spin_unlock_irq(&ioc->lock);
Tejun Heob2efa052011-12-14 00:33:39 +0100131
132 kmem_cache_free(iocontext_cachep, ioc);
Jens Axboe86db1e22008-01-29 14:53:40 +0100133}
134
Tejun Heo42ec57a2011-12-14 00:33:37 +0100135/**
136 * put_io_context - put a reference of io_context
137 * @ioc: io_context to put
138 *
139 * Decrement reference count of @ioc and release it if the count reaches
Tejun Heo11a31222012-02-07 07:51:30 +0100140 * zero.
Jens Axboe86db1e22008-01-29 14:53:40 +0100141 */
Tejun Heo11a31222012-02-07 07:51:30 +0100142void put_io_context(struct io_context *ioc)
Jens Axboe86db1e22008-01-29 14:53:40 +0100143{
Tejun Heob2efa052011-12-14 00:33:39 +0100144 unsigned long flags;
Xiaotian Fengff8c1472012-03-14 15:34:48 +0100145 bool free_ioc = false;
Tejun Heob2efa052011-12-14 00:33:39 +0100146
Jens Axboe86db1e22008-01-29 14:53:40 +0100147 if (ioc == NULL)
Tejun Heo42ec57a2011-12-14 00:33:37 +0100148 return;
Jens Axboe86db1e22008-01-29 14:53:40 +0100149
Tejun Heo42ec57a2011-12-14 00:33:37 +0100150 BUG_ON(atomic_long_read(&ioc->refcount) <= 0);
Jens Axboe86db1e22008-01-29 14:53:40 +0100151
Tejun Heob2efa052011-12-14 00:33:39 +0100152 /*
Tejun Heo11a31222012-02-07 07:51:30 +0100153 * Releasing ioc requires reverse order double locking and we may
154 * already be holding a queue_lock. Do it asynchronously from wq.
Tejun Heob2efa052011-12-14 00:33:39 +0100155 */
Tejun Heo11a31222012-02-07 07:51:30 +0100156 if (atomic_long_dec_and_test(&ioc->refcount)) {
157 spin_lock_irqsave(&ioc->lock, flags);
158 if (!hlist_empty(&ioc->icq_list))
Viresh Kumar695588f2013-04-24 17:12:56 +0530159 queue_work(system_power_efficient_wq,
160 &ioc->release_work);
Xiaotian Fengff8c1472012-03-14 15:34:48 +0100161 else
162 free_ioc = true;
Tejun Heo11a31222012-02-07 07:51:30 +0100163 spin_unlock_irqrestore(&ioc->lock, flags);
Tejun Heob2efa052011-12-14 00:33:39 +0100164 }
Xiaotian Fengff8c1472012-03-14 15:34:48 +0100165
166 if (free_ioc)
167 kmem_cache_free(iocontext_cachep, ioc);
Jens Axboe86db1e22008-01-29 14:53:40 +0100168}
Jens Axboe86db1e22008-01-29 14:53:40 +0100169
Tejun Heof6e8d012012-03-05 13:15:26 -0800170/**
171 * put_io_context_active - put active reference on ioc
172 * @ioc: ioc of interest
173 *
174 * Undo get_io_context_active(). If active reference reaches zero after
175 * put, @ioc can never issue further IOs and ioscheds are notified.
176 */
177void put_io_context_active(struct io_context *ioc)
Jens Axboe86db1e22008-01-29 14:53:40 +0100178{
Tejun Heof6e8d012012-03-05 13:15:26 -0800179 struct io_cq *icq;
Jens Axboe86db1e22008-01-29 14:53:40 +0100180
Tejun Heof6e8d012012-03-05 13:15:26 -0800181 if (!atomic_dec_and_test(&ioc->active_ref)) {
Tejun Heo621032a2012-02-15 09:45:53 +0100182 put_io_context(ioc);
183 return;
184 }
185
John Ognessa43f0852020-06-19 17:23:17 +0206186 spin_lock_irq(&ioc->lock);
Sasha Levinb67bfe02013-02-27 17:06:00 -0800187 hlist_for_each_entry(icq, &ioc->icq_list, ioc_node) {
Tejun Heo621032a2012-02-15 09:45:53 +0100188 if (icq->flags & ICQ_EXITED)
189 continue;
Omar Sandoval3d492c22017-02-10 10:32:34 -0800190
Jens Axboea1ce35f2018-10-29 10:23:51 -0600191 ioc_exit_icq(icq);
Tejun Heo621032a2012-02-15 09:45:53 +0100192 }
John Ognessa43f0852020-06-19 17:23:17 +0206193 spin_unlock_irq(&ioc->lock);
Tejun Heo621032a2012-02-15 09:45:53 +0100194
Tejun Heo11a31222012-02-07 07:51:30 +0100195 put_io_context(ioc);
Jens Axboe86db1e22008-01-29 14:53:40 +0100196}
197
Tejun Heof6e8d012012-03-05 13:15:26 -0800198/* Called by the exiting task */
199void exit_io_context(struct task_struct *task)
200{
201 struct io_context *ioc;
202
203 task_lock(task);
204 ioc = task->io_context;
205 task->io_context = NULL;
206 task_unlock(task);
207
208 atomic_dec(&ioc->nr_tasks);
209 put_io_context_active(ioc);
210}
211
Jens Axboe7b36a712017-03-02 13:59:08 -0700212static void __ioc_clear_queue(struct list_head *icq_list)
213{
214 unsigned long flags;
215
Sahitya Tummala30a2da72020-03-11 16:07:50 +0530216 rcu_read_lock();
Jens Axboe7b36a712017-03-02 13:59:08 -0700217 while (!list_empty(icq_list)) {
218 struct io_cq *icq = list_entry(icq_list->next,
Jens Axboea1ce35f2018-10-29 10:23:51 -0600219 struct io_cq, q_node);
Jens Axboe7b36a712017-03-02 13:59:08 -0700220 struct io_context *ioc = icq->ioc;
221
222 spin_lock_irqsave(&ioc->lock, flags);
Sahitya Tummala30a2da72020-03-11 16:07:50 +0530223 if (icq->flags & ICQ_DESTROYED) {
224 spin_unlock_irqrestore(&ioc->lock, flags);
225 continue;
226 }
Jens Axboe7b36a712017-03-02 13:59:08 -0700227 ioc_destroy_icq(icq);
228 spin_unlock_irqrestore(&ioc->lock, flags);
229 }
Sahitya Tummala30a2da72020-03-11 16:07:50 +0530230 rcu_read_unlock();
Jens Axboe7b36a712017-03-02 13:59:08 -0700231}
232
Tejun Heo7e5a8792011-12-14 00:33:42 +0100233/**
234 * ioc_clear_queue - break any ioc association with the specified queue
235 * @q: request_queue being cleared
236 *
Jens Axboe7b36a712017-03-02 13:59:08 -0700237 * Walk @q->icq_list and exit all io_cq's.
Tejun Heo7e5a8792011-12-14 00:33:42 +0100238 */
239void ioc_clear_queue(struct request_queue *q)
240{
Jens Axboe7b36a712017-03-02 13:59:08 -0700241 LIST_HEAD(icq_list);
Tejun Heo7e5a8792011-12-14 00:33:42 +0100242
Christoph Hellwig0d945c12018-11-15 12:17:28 -0700243 spin_lock_irq(&q->queue_lock);
Jens Axboe7b36a712017-03-02 13:59:08 -0700244 list_splice_init(&q->icq_list, &icq_list);
Christoph Hellwig0d945c12018-11-15 12:17:28 -0700245 spin_unlock_irq(&q->queue_lock);
Tejun Heo7e5a8792011-12-14 00:33:42 +0100246
Jens Axboea1ce35f2018-10-29 10:23:51 -0600247 __ioc_clear_queue(&icq_list);
Tejun Heo7e5a8792011-12-14 00:33:42 +0100248}
249
Tejun Heo24acfc32012-03-05 13:15:24 -0800250int create_task_io_context(struct task_struct *task, gfp_t gfp_flags, int node)
Jens Axboe86db1e22008-01-29 14:53:40 +0100251{
Paul Bolledf415652011-06-06 05:11:34 +0200252 struct io_context *ioc;
Eric Dumazet3c9c7082012-05-31 13:39:05 +0200253 int ret;
Jens Axboe86db1e22008-01-29 14:53:40 +0100254
Tejun Heo42ec57a2011-12-14 00:33:37 +0100255 ioc = kmem_cache_alloc_node(iocontext_cachep, gfp_flags | __GFP_ZERO,
256 node);
257 if (unlikely(!ioc))
Tejun Heo24acfc32012-03-05 13:15:24 -0800258 return -ENOMEM;
Tejun Heo42ec57a2011-12-14 00:33:37 +0100259
260 /* initialize */
261 atomic_long_set(&ioc->refcount, 1);
Olof Johansson4638a832012-08-01 12:17:27 +0200262 atomic_set(&ioc->nr_tasks, 1);
Tejun Heof6e8d012012-03-05 13:15:26 -0800263 atomic_set(&ioc->active_ref, 1);
Tejun Heo42ec57a2011-12-14 00:33:37 +0100264 spin_lock_init(&ioc->lock);
Shakeel Buttc1379692018-07-03 10:14:46 -0700265 INIT_RADIX_TREE(&ioc->icq_tree, GFP_ATOMIC);
Tejun Heoc5869802011-12-14 00:33:41 +0100266 INIT_HLIST_HEAD(&ioc->icq_list);
Tejun Heob2efa052011-12-14 00:33:39 +0100267 INIT_WORK(&ioc->release_work, ioc_release_fn);
Jens Axboe86db1e22008-01-29 14:53:40 +0100268
Tejun Heofd638362011-12-25 14:29:14 +0100269 /*
270 * Try to install. ioc shouldn't be installed if someone else
271 * already did or @task, which isn't %current, is exiting. Note
272 * that we need to allow ioc creation on exiting %current as exit
273 * path may issue IOs from e.g. exit_files(). The exit path is
274 * responsible for not issuing IO after exit_io_context().
275 */
Tejun Heo6e736be2011-12-14 00:33:38 +0100276 task_lock(task);
Tejun Heofd638362011-12-25 14:29:14 +0100277 if (!task->io_context &&
278 (task == current || !(task->flags & PF_EXITING)))
Tejun Heo6e736be2011-12-14 00:33:38 +0100279 task->io_context = ioc;
Tejun Heof2dbd762011-12-14 00:33:40 +0100280 else
Tejun Heo6e736be2011-12-14 00:33:38 +0100281 kmem_cache_free(iocontext_cachep, ioc);
Eric Dumazet3c9c7082012-05-31 13:39:05 +0200282
283 ret = task->io_context ? 0 : -EBUSY;
284
Tejun Heo6e736be2011-12-14 00:33:38 +0100285 task_unlock(task);
Tejun Heo24acfc32012-03-05 13:15:24 -0800286
Eric Dumazet3c9c7082012-05-31 13:39:05 +0200287 return ret;
Jens Axboe86db1e22008-01-29 14:53:40 +0100288}
Jens Axboe86db1e22008-01-29 14:53:40 +0100289
Tejun Heo6e736be2011-12-14 00:33:38 +0100290/**
291 * get_task_io_context - get io_context of a task
292 * @task: task of interest
293 * @gfp_flags: allocation flags, used if allocation is necessary
294 * @node: allocation node, used if allocation is necessary
Jens Axboe86db1e22008-01-29 14:53:40 +0100295 *
Tejun Heo6e736be2011-12-14 00:33:38 +0100296 * Return io_context of @task. If it doesn't exist, it is created with
297 * @gfp_flags and @node. The returned io_context has its reference count
298 * incremented.
299 *
300 * This function always goes through task_lock() and it's better to use
Tejun Heof2dbd762011-12-14 00:33:40 +0100301 * %current->io_context + get_io_context() for %current.
Jens Axboe86db1e22008-01-29 14:53:40 +0100302 */
Tejun Heo6e736be2011-12-14 00:33:38 +0100303struct io_context *get_task_io_context(struct task_struct *task,
304 gfp_t gfp_flags, int node)
Jens Axboe86db1e22008-01-29 14:53:40 +0100305{
Tejun Heo6e736be2011-12-14 00:33:38 +0100306 struct io_context *ioc;
Jens Axboe86db1e22008-01-29 14:53:40 +0100307
Mel Gormand0164ad2015-11-06 16:28:21 -0800308 might_sleep_if(gfpflags_allow_blocking(gfp_flags));
Jens Axboe86db1e22008-01-29 14:53:40 +0100309
Tejun Heof2dbd762011-12-14 00:33:40 +0100310 do {
311 task_lock(task);
312 ioc = task->io_context;
313 if (likely(ioc)) {
314 get_io_context(ioc);
315 task_unlock(task);
316 return ioc;
317 }
Tejun Heo6e736be2011-12-14 00:33:38 +0100318 task_unlock(task);
Tejun Heo24acfc32012-03-05 13:15:24 -0800319 } while (!create_task_io_context(task, gfp_flags, node));
Tejun Heo6e736be2011-12-14 00:33:38 +0100320
Tejun Heof2dbd762011-12-14 00:33:40 +0100321 return NULL;
Jens Axboe86db1e22008-01-29 14:53:40 +0100322}
Jens Axboe86db1e22008-01-29 14:53:40 +0100323
Tejun Heo47fdd4c2011-12-14 00:33:42 +0100324/**
325 * ioc_lookup_icq - lookup io_cq from ioc
326 * @ioc: the associated io_context
327 * @q: the associated request_queue
328 *
329 * Look up io_cq associated with @ioc - @q pair from @ioc. Must be called
330 * with @q->queue_lock held.
331 */
332struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q)
333{
334 struct io_cq *icq;
335
Christoph Hellwig0d945c12018-11-15 12:17:28 -0700336 lockdep_assert_held(&q->queue_lock);
Tejun Heo47fdd4c2011-12-14 00:33:42 +0100337
338 /*
339 * icq's are indexed from @ioc using radix tree and hint pointer,
340 * both of which are protected with RCU. All removals are done
341 * holding both q and ioc locks, and we're holding q lock - if we
342 * find a icq which points to us, it's guaranteed to be valid.
343 */
344 rcu_read_lock();
345 icq = rcu_dereference(ioc->icq_hint);
346 if (icq && icq->q == q)
347 goto out;
348
349 icq = radix_tree_lookup(&ioc->icq_tree, q->id);
350 if (icq && icq->q == q)
351 rcu_assign_pointer(ioc->icq_hint, icq); /* allowed to race */
352 else
353 icq = NULL;
354out:
355 rcu_read_unlock();
356 return icq;
357}
358EXPORT_SYMBOL(ioc_lookup_icq);
359
Tejun Heof1f8cc92011-12-14 00:33:42 +0100360/**
361 * ioc_create_icq - create and link io_cq
Tejun Heo24acfc32012-03-05 13:15:24 -0800362 * @ioc: io_context of interest
Tejun Heof1f8cc92011-12-14 00:33:42 +0100363 * @q: request_queue of interest
364 * @gfp_mask: allocation mask
365 *
Tejun Heo24acfc32012-03-05 13:15:24 -0800366 * Make sure io_cq linking @ioc and @q exists. If icq doesn't exist, they
367 * will be created using @gfp_mask.
Tejun Heof1f8cc92011-12-14 00:33:42 +0100368 *
369 * The caller is responsible for ensuring @ioc won't go away and @q is
370 * alive and will stay alive until this function returns.
371 */
Tejun Heo24acfc32012-03-05 13:15:24 -0800372struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q,
373 gfp_t gfp_mask)
Tejun Heof1f8cc92011-12-14 00:33:42 +0100374{
375 struct elevator_type *et = q->elevator->type;
Tejun Heof1f8cc92011-12-14 00:33:42 +0100376 struct io_cq *icq;
377
378 /* allocate stuff */
Tejun Heof1f8cc92011-12-14 00:33:42 +0100379 icq = kmem_cache_alloc_node(et->icq_cache, gfp_mask | __GFP_ZERO,
380 q->node);
381 if (!icq)
382 return NULL;
383
Jan Kara5e4c0d972013-09-11 14:26:05 -0700384 if (radix_tree_maybe_preload(gfp_mask) < 0) {
Tejun Heof1f8cc92011-12-14 00:33:42 +0100385 kmem_cache_free(et->icq_cache, icq);
386 return NULL;
387 }
388
389 icq->ioc = ioc;
390 icq->q = q;
391 INIT_LIST_HEAD(&icq->q_node);
392 INIT_HLIST_NODE(&icq->ioc_node);
393
394 /* lock both q and ioc and try to link @icq */
Christoph Hellwig0d945c12018-11-15 12:17:28 -0700395 spin_lock_irq(&q->queue_lock);
Tejun Heof1f8cc92011-12-14 00:33:42 +0100396 spin_lock(&ioc->lock);
397
398 if (likely(!radix_tree_insert(&ioc->icq_tree, q->id, icq))) {
399 hlist_add_head(&icq->ioc_node, &ioc->icq_list);
400 list_add(&icq->q_node, &q->icq_list);
Jens Axboef9cd4bf2018-11-01 16:41:41 -0600401 if (et->ops.init_icq)
402 et->ops.init_icq(icq);
Tejun Heof1f8cc92011-12-14 00:33:42 +0100403 } else {
404 kmem_cache_free(et->icq_cache, icq);
405 icq = ioc_lookup_icq(ioc, q);
406 if (!icq)
407 printk(KERN_ERR "cfq: icq link failed!\n");
408 }
409
410 spin_unlock(&ioc->lock);
Christoph Hellwig0d945c12018-11-15 12:17:28 -0700411 spin_unlock_irq(&q->queue_lock);
Tejun Heof1f8cc92011-12-14 00:33:42 +0100412 radix_tree_preload_end();
413 return icq;
414}
415
Adrian Bunk13341592008-02-18 13:45:53 +0100416static int __init blk_ioc_init(void)
Jens Axboe86db1e22008-01-29 14:53:40 +0100417{
418 iocontext_cachep = kmem_cache_create("blkdev_ioc",
419 sizeof(struct io_context), 0, SLAB_PANIC, NULL);
420 return 0;
421}
422subsys_initcall(blk_ioc_init);