Greg Kroah-Hartman | b244131 | 2017-11-01 15:07:57 +0100 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0 |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 2 | /* |
| 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 Heo | 5a0e3ad | 2010-03-24 17:04:11 +0900 | [diff] [blame] | 10 | #include <linux/slab.h> |
Ingo Molnar | f719ff9b | 2017-02-06 10:57:33 +0100 | [diff] [blame] | 11 | #include <linux/sched/task.h> |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 12 | |
| 13 | #include "blk.h" |
| 14 | |
| 15 | /* |
| 16 | * For io context allocations |
| 17 | */ |
| 18 | static struct kmem_cache *iocontext_cachep; |
| 19 | |
Tejun Heo | 6e736be | 2011-12-14 00:33:38 +0100 | [diff] [blame] | 20 | /** |
| 21 | * get_io_context - increment reference count to io_context |
| 22 | * @ioc: io_context to get |
| 23 | * |
| 24 | * Increment reference count to @ioc. |
| 25 | */ |
| 26 | void 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 Heo | 6e736be | 2011-12-14 00:33:38 +0100 | [diff] [blame] | 31 | |
Tejun Heo | 7e5a879 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 32 | static 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 Sandoval | 3d492c2 | 2017-02-10 10:32:34 -0800 | [diff] [blame] | 39 | /* |
Jens Axboe | 7b36a71 | 2017-03-02 13:59:08 -0700 | [diff] [blame] | 40 | * Exit an icq. Called with ioc locked for blk-mq, and with both ioc |
| 41 | * and queue locked for legacy. |
Omar Sandoval | 3d492c2 | 2017-02-10 10:32:34 -0800 | [diff] [blame] | 42 | */ |
Tejun Heo | 7e5a879 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 43 | static void ioc_exit_icq(struct io_cq *icq) |
| 44 | { |
Tejun Heo | 621032a | 2012-02-15 09:45:53 +0100 | [diff] [blame] | 45 | struct elevator_type *et = icq->q->elevator->type; |
| 46 | |
| 47 | if (icq->flags & ICQ_EXITED) |
| 48 | return; |
| 49 | |
Jens Axboe | f9cd4bf | 2018-11-01 16:41:41 -0600 | [diff] [blame] | 50 | if (et->ops.exit_icq) |
| 51 | et->ops.exit_icq(icq); |
Tejun Heo | 621032a | 2012-02-15 09:45:53 +0100 | [diff] [blame] | 52 | |
| 53 | icq->flags |= ICQ_EXITED; |
| 54 | } |
| 55 | |
Jens Axboe | 7b36a71 | 2017-03-02 13:59:08 -0700 | [diff] [blame] | 56 | /* |
| 57 | * Release an icq. Called with ioc locked for blk-mq, and with both ioc |
| 58 | * and queue locked for legacy. |
| 59 | */ |
Tejun Heo | 621032a | 2012-02-15 09:45:53 +0100 | [diff] [blame] | 60 | static void ioc_destroy_icq(struct io_cq *icq) |
| 61 | { |
Tejun Heo | 7e5a879 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 62 | 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 Heo | 7e5a879 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 67 | |
| 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. McKenney | ec6c676a | 2014-02-17 13:35:57 -0800 | [diff] [blame] | 77 | if (rcu_access_pointer(ioc->icq_hint) == icq) |
Tejun Heo | 7e5a879 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 78 | rcu_assign_pointer(ioc->icq_hint, NULL); |
| 79 | |
Tejun Heo | 621032a | 2012-02-15 09:45:53 +0100 | [diff] [blame] | 80 | ioc_exit_icq(icq); |
Tejun Heo | 7e5a879 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 81 | |
| 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 Tummala | 30a2da7 | 2020-03-11 16:07:50 +0530 | [diff] [blame] | 87 | icq->flags |= ICQ_DESTROYED; |
Tejun Heo | 7e5a879 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 88 | call_rcu(&icq->__rcu_head, icq_free_icq_rcu); |
| 89 | } |
| 90 | |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 91 | /* |
| 92 | * Slow path for ioc release in put_io_context(). Performs double-lock |
Tejun Heo | c586980 | 2011-12-14 00:33:41 +0100 | [diff] [blame] | 93 | * dancing to unlink all icq's and then frees ioc. |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 94 | */ |
| 95 | static void ioc_release_fn(struct work_struct *work) |
| 96 | { |
| 97 | struct io_context *ioc = container_of(work, struct io_context, |
| 98 | release_work); |
John Ogness | a43f085 | 2020-06-19 17:23:17 +0206 | [diff] [blame] | 99 | spin_lock_irq(&ioc->lock); |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 100 | |
Tejun Heo | c586980 | 2011-12-14 00:33:41 +0100 | [diff] [blame] | 101 | while (!hlist_empty(&ioc->icq_list)) { |
| 102 | struct io_cq *icq = hlist_entry(ioc->icq_list.first, |
| 103 | struct io_cq, ioc_node); |
Tejun Heo | 2274b02 | 2012-02-15 09:45:52 +0100 | [diff] [blame] | 104 | struct request_queue *q = icq->q; |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 105 | |
Christoph Hellwig | 0d945c1 | 2018-11-15 12:17:28 -0700 | [diff] [blame] | 106 | if (spin_trylock(&q->queue_lock)) { |
Tejun Heo | 621032a | 2012-02-15 09:45:53 +0100 | [diff] [blame] | 107 | ioc_destroy_icq(icq); |
Christoph Hellwig | 0d945c1 | 2018-11-15 12:17:28 -0700 | [diff] [blame] | 108 | spin_unlock(&q->queue_lock); |
Tejun Heo | 2274b02 | 2012-02-15 09:45:52 +0100 | [diff] [blame] | 109 | } else { |
John Ogness | ab96bba | 2020-06-19 17:23:18 +0206 | [diff] [blame] | 110 | /* 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 Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 127 | } |
Jens Axboe | ffc4e75 | 2008-02-19 10:02:29 +0100 | [diff] [blame] | 128 | } |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 129 | |
John Ogness | a43f085 | 2020-06-19 17:23:17 +0206 | [diff] [blame] | 130 | spin_unlock_irq(&ioc->lock); |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 131 | |
| 132 | kmem_cache_free(iocontext_cachep, ioc); |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 133 | } |
| 134 | |
Tejun Heo | 42ec57a | 2011-12-14 00:33:37 +0100 | [diff] [blame] | 135 | /** |
| 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 Heo | 11a3122 | 2012-02-07 07:51:30 +0100 | [diff] [blame] | 140 | * zero. |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 141 | */ |
Tejun Heo | 11a3122 | 2012-02-07 07:51:30 +0100 | [diff] [blame] | 142 | void put_io_context(struct io_context *ioc) |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 143 | { |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 144 | unsigned long flags; |
Xiaotian Feng | ff8c147 | 2012-03-14 15:34:48 +0100 | [diff] [blame] | 145 | bool free_ioc = false; |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 146 | |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 147 | if (ioc == NULL) |
Tejun Heo | 42ec57a | 2011-12-14 00:33:37 +0100 | [diff] [blame] | 148 | return; |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 149 | |
Tejun Heo | 42ec57a | 2011-12-14 00:33:37 +0100 | [diff] [blame] | 150 | BUG_ON(atomic_long_read(&ioc->refcount) <= 0); |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 151 | |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 152 | /* |
Tejun Heo | 11a3122 | 2012-02-07 07:51:30 +0100 | [diff] [blame] | 153 | * Releasing ioc requires reverse order double locking and we may |
| 154 | * already be holding a queue_lock. Do it asynchronously from wq. |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 155 | */ |
Tejun Heo | 11a3122 | 2012-02-07 07:51:30 +0100 | [diff] [blame] | 156 | if (atomic_long_dec_and_test(&ioc->refcount)) { |
| 157 | spin_lock_irqsave(&ioc->lock, flags); |
| 158 | if (!hlist_empty(&ioc->icq_list)) |
Viresh Kumar | 695588f | 2013-04-24 17:12:56 +0530 | [diff] [blame] | 159 | queue_work(system_power_efficient_wq, |
| 160 | &ioc->release_work); |
Xiaotian Feng | ff8c147 | 2012-03-14 15:34:48 +0100 | [diff] [blame] | 161 | else |
| 162 | free_ioc = true; |
Tejun Heo | 11a3122 | 2012-02-07 07:51:30 +0100 | [diff] [blame] | 163 | spin_unlock_irqrestore(&ioc->lock, flags); |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 164 | } |
Xiaotian Feng | ff8c147 | 2012-03-14 15:34:48 +0100 | [diff] [blame] | 165 | |
| 166 | if (free_ioc) |
| 167 | kmem_cache_free(iocontext_cachep, ioc); |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 168 | } |
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 | /** |
| 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 | */ |
| 177 | void put_io_context_active(struct io_context *ioc) |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 178 | { |
Tejun Heo | f6e8d01 | 2012-03-05 13:15:26 -0800 | [diff] [blame] | 179 | struct io_cq *icq; |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 180 | |
Tejun Heo | f6e8d01 | 2012-03-05 13:15:26 -0800 | [diff] [blame] | 181 | if (!atomic_dec_and_test(&ioc->active_ref)) { |
Tejun Heo | 621032a | 2012-02-15 09:45:53 +0100 | [diff] [blame] | 182 | put_io_context(ioc); |
| 183 | return; |
| 184 | } |
| 185 | |
John Ogness | a43f085 | 2020-06-19 17:23:17 +0206 | [diff] [blame] | 186 | spin_lock_irq(&ioc->lock); |
Sasha Levin | b67bfe0 | 2013-02-27 17:06:00 -0800 | [diff] [blame] | 187 | hlist_for_each_entry(icq, &ioc->icq_list, ioc_node) { |
Tejun Heo | 621032a | 2012-02-15 09:45:53 +0100 | [diff] [blame] | 188 | if (icq->flags & ICQ_EXITED) |
| 189 | continue; |
Omar Sandoval | 3d492c2 | 2017-02-10 10:32:34 -0800 | [diff] [blame] | 190 | |
Jens Axboe | a1ce35f | 2018-10-29 10:23:51 -0600 | [diff] [blame] | 191 | ioc_exit_icq(icq); |
Tejun Heo | 621032a | 2012-02-15 09:45:53 +0100 | [diff] [blame] | 192 | } |
John Ogness | a43f085 | 2020-06-19 17:23:17 +0206 | [diff] [blame] | 193 | spin_unlock_irq(&ioc->lock); |
Tejun Heo | 621032a | 2012-02-15 09:45:53 +0100 | [diff] [blame] | 194 | |
Tejun Heo | 11a3122 | 2012-02-07 07:51:30 +0100 | [diff] [blame] | 195 | put_io_context(ioc); |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 196 | } |
| 197 | |
Tejun Heo | f6e8d01 | 2012-03-05 13:15:26 -0800 | [diff] [blame] | 198 | /* Called by the exiting task */ |
| 199 | void 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 Axboe | 7b36a71 | 2017-03-02 13:59:08 -0700 | [diff] [blame] | 212 | static void __ioc_clear_queue(struct list_head *icq_list) |
| 213 | { |
| 214 | unsigned long flags; |
| 215 | |
Sahitya Tummala | 30a2da7 | 2020-03-11 16:07:50 +0530 | [diff] [blame] | 216 | rcu_read_lock(); |
Jens Axboe | 7b36a71 | 2017-03-02 13:59:08 -0700 | [diff] [blame] | 217 | while (!list_empty(icq_list)) { |
| 218 | struct io_cq *icq = list_entry(icq_list->next, |
Jens Axboe | a1ce35f | 2018-10-29 10:23:51 -0600 | [diff] [blame] | 219 | struct io_cq, q_node); |
Jens Axboe | 7b36a71 | 2017-03-02 13:59:08 -0700 | [diff] [blame] | 220 | struct io_context *ioc = icq->ioc; |
| 221 | |
| 222 | spin_lock_irqsave(&ioc->lock, flags); |
Sahitya Tummala | 30a2da7 | 2020-03-11 16:07:50 +0530 | [diff] [blame] | 223 | if (icq->flags & ICQ_DESTROYED) { |
| 224 | spin_unlock_irqrestore(&ioc->lock, flags); |
| 225 | continue; |
| 226 | } |
Jens Axboe | 7b36a71 | 2017-03-02 13:59:08 -0700 | [diff] [blame] | 227 | ioc_destroy_icq(icq); |
| 228 | spin_unlock_irqrestore(&ioc->lock, flags); |
| 229 | } |
Sahitya Tummala | 30a2da7 | 2020-03-11 16:07:50 +0530 | [diff] [blame] | 230 | rcu_read_unlock(); |
Jens Axboe | 7b36a71 | 2017-03-02 13:59:08 -0700 | [diff] [blame] | 231 | } |
| 232 | |
Tejun Heo | 7e5a879 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 233 | /** |
| 234 | * ioc_clear_queue - break any ioc association with the specified queue |
| 235 | * @q: request_queue being cleared |
| 236 | * |
Jens Axboe | 7b36a71 | 2017-03-02 13:59:08 -0700 | [diff] [blame] | 237 | * Walk @q->icq_list and exit all io_cq's. |
Tejun Heo | 7e5a879 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 238 | */ |
| 239 | void ioc_clear_queue(struct request_queue *q) |
| 240 | { |
Jens Axboe | 7b36a71 | 2017-03-02 13:59:08 -0700 | [diff] [blame] | 241 | LIST_HEAD(icq_list); |
Tejun Heo | 7e5a879 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 242 | |
Christoph Hellwig | 0d945c1 | 2018-11-15 12:17:28 -0700 | [diff] [blame] | 243 | spin_lock_irq(&q->queue_lock); |
Jens Axboe | 7b36a71 | 2017-03-02 13:59:08 -0700 | [diff] [blame] | 244 | list_splice_init(&q->icq_list, &icq_list); |
Christoph Hellwig | 0d945c1 | 2018-11-15 12:17:28 -0700 | [diff] [blame] | 245 | spin_unlock_irq(&q->queue_lock); |
Tejun Heo | 7e5a879 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 246 | |
Jens Axboe | a1ce35f | 2018-10-29 10:23:51 -0600 | [diff] [blame] | 247 | __ioc_clear_queue(&icq_list); |
Tejun Heo | 7e5a879 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 248 | } |
| 249 | |
Tejun Heo | 24acfc3 | 2012-03-05 13:15:24 -0800 | [diff] [blame] | 250 | 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] | 251 | { |
Paul Bolle | df41565 | 2011-06-06 05:11:34 +0200 | [diff] [blame] | 252 | struct io_context *ioc; |
Eric Dumazet | 3c9c708 | 2012-05-31 13:39:05 +0200 | [diff] [blame] | 253 | int ret; |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 254 | |
Tejun Heo | 42ec57a | 2011-12-14 00:33:37 +0100 | [diff] [blame] | 255 | ioc = kmem_cache_alloc_node(iocontext_cachep, gfp_flags | __GFP_ZERO, |
| 256 | node); |
| 257 | if (unlikely(!ioc)) |
Tejun Heo | 24acfc3 | 2012-03-05 13:15:24 -0800 | [diff] [blame] | 258 | return -ENOMEM; |
Tejun Heo | 42ec57a | 2011-12-14 00:33:37 +0100 | [diff] [blame] | 259 | |
| 260 | /* initialize */ |
| 261 | atomic_long_set(&ioc->refcount, 1); |
Olof Johansson | 4638a83 | 2012-08-01 12:17:27 +0200 | [diff] [blame] | 262 | atomic_set(&ioc->nr_tasks, 1); |
Tejun Heo | f6e8d01 | 2012-03-05 13:15:26 -0800 | [diff] [blame] | 263 | atomic_set(&ioc->active_ref, 1); |
Tejun Heo | 42ec57a | 2011-12-14 00:33:37 +0100 | [diff] [blame] | 264 | spin_lock_init(&ioc->lock); |
Shakeel Butt | c137969 | 2018-07-03 10:14:46 -0700 | [diff] [blame] | 265 | INIT_RADIX_TREE(&ioc->icq_tree, GFP_ATOMIC); |
Tejun Heo | c586980 | 2011-12-14 00:33:41 +0100 | [diff] [blame] | 266 | INIT_HLIST_HEAD(&ioc->icq_list); |
Tejun Heo | b2efa05 | 2011-12-14 00:33:39 +0100 | [diff] [blame] | 267 | INIT_WORK(&ioc->release_work, ioc_release_fn); |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 268 | |
Tejun Heo | fd63836 | 2011-12-25 14:29:14 +0100 | [diff] [blame] | 269 | /* |
| 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 Heo | 6e736be | 2011-12-14 00:33:38 +0100 | [diff] [blame] | 276 | task_lock(task); |
Tejun Heo | fd63836 | 2011-12-25 14:29:14 +0100 | [diff] [blame] | 277 | if (!task->io_context && |
| 278 | (task == current || !(task->flags & PF_EXITING))) |
Tejun Heo | 6e736be | 2011-12-14 00:33:38 +0100 | [diff] [blame] | 279 | task->io_context = ioc; |
Tejun Heo | f2dbd76 | 2011-12-14 00:33:40 +0100 | [diff] [blame] | 280 | else |
Tejun Heo | 6e736be | 2011-12-14 00:33:38 +0100 | [diff] [blame] | 281 | kmem_cache_free(iocontext_cachep, ioc); |
Eric Dumazet | 3c9c708 | 2012-05-31 13:39:05 +0200 | [diff] [blame] | 282 | |
| 283 | ret = task->io_context ? 0 : -EBUSY; |
| 284 | |
Tejun Heo | 6e736be | 2011-12-14 00:33:38 +0100 | [diff] [blame] | 285 | task_unlock(task); |
Tejun Heo | 24acfc3 | 2012-03-05 13:15:24 -0800 | [diff] [blame] | 286 | |
Eric Dumazet | 3c9c708 | 2012-05-31 13:39:05 +0200 | [diff] [blame] | 287 | return ret; |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 288 | } |
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 | /** |
| 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 Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 295 | * |
Tejun Heo | 6e736be | 2011-12-14 00:33:38 +0100 | [diff] [blame] | 296 | * 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 Heo | f2dbd76 | 2011-12-14 00:33:40 +0100 | [diff] [blame] | 301 | * %current->io_context + get_io_context() for %current. |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 302 | */ |
Tejun Heo | 6e736be | 2011-12-14 00:33:38 +0100 | [diff] [blame] | 303 | struct io_context *get_task_io_context(struct task_struct *task, |
| 304 | gfp_t gfp_flags, int node) |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 305 | { |
Tejun Heo | 6e736be | 2011-12-14 00:33:38 +0100 | [diff] [blame] | 306 | struct io_context *ioc; |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 307 | |
Mel Gorman | d0164ad | 2015-11-06 16:28:21 -0800 | [diff] [blame] | 308 | might_sleep_if(gfpflags_allow_blocking(gfp_flags)); |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 309 | |
Tejun Heo | f2dbd76 | 2011-12-14 00:33:40 +0100 | [diff] [blame] | 310 | 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 Heo | 6e736be | 2011-12-14 00:33:38 +0100 | [diff] [blame] | 318 | task_unlock(task); |
Tejun Heo | 24acfc3 | 2012-03-05 13:15:24 -0800 | [diff] [blame] | 319 | } while (!create_task_io_context(task, gfp_flags, node)); |
Tejun Heo | 6e736be | 2011-12-14 00:33:38 +0100 | [diff] [blame] | 320 | |
Tejun Heo | f2dbd76 | 2011-12-14 00:33:40 +0100 | [diff] [blame] | 321 | return NULL; |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 322 | } |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 323 | |
Tejun Heo | 47fdd4c | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 324 | /** |
| 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 | */ |
| 332 | struct io_cq *ioc_lookup_icq(struct io_context *ioc, struct request_queue *q) |
| 333 | { |
| 334 | struct io_cq *icq; |
| 335 | |
Christoph Hellwig | 0d945c1 | 2018-11-15 12:17:28 -0700 | [diff] [blame] | 336 | lockdep_assert_held(&q->queue_lock); |
Tejun Heo | 47fdd4c | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 337 | |
| 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; |
| 354 | out: |
| 355 | rcu_read_unlock(); |
| 356 | return icq; |
| 357 | } |
| 358 | EXPORT_SYMBOL(ioc_lookup_icq); |
| 359 | |
Tejun Heo | f1f8cc9 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 360 | /** |
| 361 | * ioc_create_icq - create and link io_cq |
Tejun Heo | 24acfc3 | 2012-03-05 13:15:24 -0800 | [diff] [blame] | 362 | * @ioc: io_context of interest |
Tejun Heo | f1f8cc9 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 363 | * @q: request_queue of interest |
| 364 | * @gfp_mask: allocation mask |
| 365 | * |
Tejun Heo | 24acfc3 | 2012-03-05 13:15:24 -0800 | [diff] [blame] | 366 | * Make sure io_cq linking @ioc and @q exists. If icq doesn't exist, they |
| 367 | * will be created using @gfp_mask. |
Tejun Heo | f1f8cc9 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 368 | * |
| 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 Heo | 24acfc3 | 2012-03-05 13:15:24 -0800 | [diff] [blame] | 372 | struct io_cq *ioc_create_icq(struct io_context *ioc, struct request_queue *q, |
| 373 | gfp_t gfp_mask) |
Tejun Heo | f1f8cc9 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 374 | { |
| 375 | struct elevator_type *et = q->elevator->type; |
Tejun Heo | f1f8cc9 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 376 | struct io_cq *icq; |
| 377 | |
| 378 | /* allocate stuff */ |
Tejun Heo | f1f8cc9 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 379 | icq = kmem_cache_alloc_node(et->icq_cache, gfp_mask | __GFP_ZERO, |
| 380 | q->node); |
| 381 | if (!icq) |
| 382 | return NULL; |
| 383 | |
Jan Kara | 5e4c0d97 | 2013-09-11 14:26:05 -0700 | [diff] [blame] | 384 | if (radix_tree_maybe_preload(gfp_mask) < 0) { |
Tejun Heo | f1f8cc9 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 385 | 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 Hellwig | 0d945c1 | 2018-11-15 12:17:28 -0700 | [diff] [blame] | 395 | spin_lock_irq(&q->queue_lock); |
Tejun Heo | f1f8cc9 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 396 | 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 Axboe | f9cd4bf | 2018-11-01 16:41:41 -0600 | [diff] [blame] | 401 | if (et->ops.init_icq) |
| 402 | et->ops.init_icq(icq); |
Tejun Heo | f1f8cc9 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 403 | } 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 Hellwig | 0d945c1 | 2018-11-15 12:17:28 -0700 | [diff] [blame] | 411 | spin_unlock_irq(&q->queue_lock); |
Tejun Heo | f1f8cc9 | 2011-12-14 00:33:42 +0100 | [diff] [blame] | 412 | radix_tree_preload_end(); |
| 413 | return icq; |
| 414 | } |
| 415 | |
Adrian Bunk | 1334159 | 2008-02-18 13:45:53 +0100 | [diff] [blame] | 416 | static int __init blk_ioc_init(void) |
Jens Axboe | 86db1e2 | 2008-01-29 14:53:40 +0100 | [diff] [blame] | 417 | { |
| 418 | iocontext_cachep = kmem_cache_create("blkdev_ioc", |
| 419 | sizeof(struct io_context), 0, SLAB_PANIC, NULL); |
| 420 | return 0; |
| 421 | } |
| 422 | subsys_initcall(blk_ioc_init); |