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1 | /* | |
2 | * Copyright (C) 1991, 1992 Linus Torvalds | |
3 | * Copyright (C) 1994, Karl Keyte: Added support for disk statistics | |
4 | * Elevator latency, (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE | |
5 | * Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de> | |
6 | * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au> | |
7 | * - July2000 | |
8 | * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001 | |
9 | */ | |
10 | ||
11 | /* | |
12 | * This handles all read/write requests to block devices | |
13 | */ | |
14 | #include <linux/kernel.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/backing-dev.h> | |
17 | #include <linux/bio.h> | |
18 | #include <linux/blkdev.h> | |
19 | #include <linux/highmem.h> | |
20 | #include <linux/mm.h> | |
21 | #include <linux/kernel_stat.h> | |
22 | #include <linux/string.h> | |
23 | #include <linux/init.h> | |
24 | #include <linux/completion.h> | |
25 | #include <linux/slab.h> | |
26 | #include <linux/swap.h> | |
27 | #include <linux/writeback.h> | |
28 | #include <linux/task_io_accounting_ops.h> | |
29 | #include <linux/interrupt.h> | |
30 | #include <linux/cpu.h> | |
31 | #include <linux/blktrace_api.h> | |
32 | #include <linux/fault-inject.h> | |
33 | ||
34 | #include "blk.h" | |
35 | ||
36 | static int __make_request(struct request_queue *q, struct bio *bio); | |
37 | ||
38 | /* | |
39 | * For the allocated request tables | |
40 | */ | |
41 | static struct kmem_cache *request_cachep; | |
42 | ||
43 | /* | |
44 | * For queue allocation | |
45 | */ | |
46 | struct kmem_cache *blk_requestq_cachep; | |
47 | ||
48 | /* | |
49 | * Controlling structure to kblockd | |
50 | */ | |
51 | static struct workqueue_struct *kblockd_workqueue; | |
52 | ||
53 | static DEFINE_PER_CPU(struct list_head, blk_cpu_done); | |
54 | ||
55 | static void drive_stat_acct(struct request *rq, int new_io) | |
56 | { | |
57 | struct hd_struct *part; | |
58 | int rw = rq_data_dir(rq); | |
59 | int cpu; | |
60 | ||
61 | if (!blk_fs_request(rq) || !rq->rq_disk) | |
62 | return; | |
63 | ||
64 | cpu = disk_stat_lock(); | |
65 | part = disk_map_sector_rcu(rq->rq_disk, rq->sector); | |
66 | ||
67 | if (!new_io) | |
68 | all_stat_inc(cpu, rq->rq_disk, part, merges[rw], rq->sector); | |
69 | else { | |
70 | disk_round_stats(cpu, rq->rq_disk); | |
71 | rq->rq_disk->in_flight++; | |
72 | if (part) { | |
73 | part_round_stats(cpu, part); | |
74 | part->in_flight++; | |
75 | } | |
76 | } | |
77 | ||
78 | disk_stat_unlock(); | |
79 | } | |
80 | ||
81 | void blk_queue_congestion_threshold(struct request_queue *q) | |
82 | { | |
83 | int nr; | |
84 | ||
85 | nr = q->nr_requests - (q->nr_requests / 8) + 1; | |
86 | if (nr > q->nr_requests) | |
87 | nr = q->nr_requests; | |
88 | q->nr_congestion_on = nr; | |
89 | ||
90 | nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1; | |
91 | if (nr < 1) | |
92 | nr = 1; | |
93 | q->nr_congestion_off = nr; | |
94 | } | |
95 | ||
96 | /** | |
97 | * blk_get_backing_dev_info - get the address of a queue's backing_dev_info | |
98 | * @bdev: device | |
99 | * | |
100 | * Locates the passed device's request queue and returns the address of its | |
101 | * backing_dev_info | |
102 | * | |
103 | * Will return NULL if the request queue cannot be located. | |
104 | */ | |
105 | struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev) | |
106 | { | |
107 | struct backing_dev_info *ret = NULL; | |
108 | struct request_queue *q = bdev_get_queue(bdev); | |
109 | ||
110 | if (q) | |
111 | ret = &q->backing_dev_info; | |
112 | return ret; | |
113 | } | |
114 | EXPORT_SYMBOL(blk_get_backing_dev_info); | |
115 | ||
116 | void blk_rq_init(struct request_queue *q, struct request *rq) | |
117 | { | |
118 | memset(rq, 0, sizeof(*rq)); | |
119 | ||
120 | INIT_LIST_HEAD(&rq->queuelist); | |
121 | INIT_LIST_HEAD(&rq->donelist); | |
122 | rq->q = q; | |
123 | rq->sector = rq->hard_sector = (sector_t) -1; | |
124 | INIT_HLIST_NODE(&rq->hash); | |
125 | RB_CLEAR_NODE(&rq->rb_node); | |
126 | rq->cmd = rq->__cmd; | |
127 | rq->tag = -1; | |
128 | rq->ref_count = 1; | |
129 | } | |
130 | EXPORT_SYMBOL(blk_rq_init); | |
131 | ||
132 | static void req_bio_endio(struct request *rq, struct bio *bio, | |
133 | unsigned int nbytes, int error) | |
134 | { | |
135 | struct request_queue *q = rq->q; | |
136 | ||
137 | if (&q->bar_rq != rq) { | |
138 | if (error) | |
139 | clear_bit(BIO_UPTODATE, &bio->bi_flags); | |
140 | else if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) | |
141 | error = -EIO; | |
142 | ||
143 | if (unlikely(nbytes > bio->bi_size)) { | |
144 | printk(KERN_ERR "%s: want %u bytes done, %u left\n", | |
145 | __func__, nbytes, bio->bi_size); | |
146 | nbytes = bio->bi_size; | |
147 | } | |
148 | ||
149 | bio->bi_size -= nbytes; | |
150 | bio->bi_sector += (nbytes >> 9); | |
151 | ||
152 | if (bio_integrity(bio)) | |
153 | bio_integrity_advance(bio, nbytes); | |
154 | ||
155 | if (bio->bi_size == 0) | |
156 | bio_endio(bio, error); | |
157 | } else { | |
158 | ||
159 | /* | |
160 | * Okay, this is the barrier request in progress, just | |
161 | * record the error; | |
162 | */ | |
163 | if (error && !q->orderr) | |
164 | q->orderr = error; | |
165 | } | |
166 | } | |
167 | ||
168 | void blk_dump_rq_flags(struct request *rq, char *msg) | |
169 | { | |
170 | int bit; | |
171 | ||
172 | printk(KERN_INFO "%s: dev %s: type=%x, flags=%x\n", msg, | |
173 | rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type, | |
174 | rq->cmd_flags); | |
175 | ||
176 | printk(KERN_INFO " sector %llu, nr/cnr %lu/%u\n", | |
177 | (unsigned long long)rq->sector, | |
178 | rq->nr_sectors, | |
179 | rq->current_nr_sectors); | |
180 | printk(KERN_INFO " bio %p, biotail %p, buffer %p, data %p, len %u\n", | |
181 | rq->bio, rq->biotail, | |
182 | rq->buffer, rq->data, | |
183 | rq->data_len); | |
184 | ||
185 | if (blk_pc_request(rq)) { | |
186 | printk(KERN_INFO " cdb: "); | |
187 | for (bit = 0; bit < BLK_MAX_CDB; bit++) | |
188 | printk("%02x ", rq->cmd[bit]); | |
189 | printk("\n"); | |
190 | } | |
191 | } | |
192 | EXPORT_SYMBOL(blk_dump_rq_flags); | |
193 | ||
194 | /* | |
195 | * "plug" the device if there are no outstanding requests: this will | |
196 | * force the transfer to start only after we have put all the requests | |
197 | * on the list. | |
198 | * | |
199 | * This is called with interrupts off and no requests on the queue and | |
200 | * with the queue lock held. | |
201 | */ | |
202 | void blk_plug_device(struct request_queue *q) | |
203 | { | |
204 | WARN_ON(!irqs_disabled()); | |
205 | ||
206 | /* | |
207 | * don't plug a stopped queue, it must be paired with blk_start_queue() | |
208 | * which will restart the queueing | |
209 | */ | |
210 | if (blk_queue_stopped(q)) | |
211 | return; | |
212 | ||
213 | if (!queue_flag_test_and_set(QUEUE_FLAG_PLUGGED, q)) { | |
214 | mod_timer(&q->unplug_timer, jiffies + q->unplug_delay); | |
215 | blk_add_trace_generic(q, NULL, 0, BLK_TA_PLUG); | |
216 | } | |
217 | } | |
218 | EXPORT_SYMBOL(blk_plug_device); | |
219 | ||
220 | /** | |
221 | * blk_plug_device_unlocked - plug a device without queue lock held | |
222 | * @q: The &struct request_queue to plug | |
223 | * | |
224 | * Description: | |
225 | * Like @blk_plug_device(), but grabs the queue lock and disables | |
226 | * interrupts. | |
227 | **/ | |
228 | void blk_plug_device_unlocked(struct request_queue *q) | |
229 | { | |
230 | unsigned long flags; | |
231 | ||
232 | spin_lock_irqsave(q->queue_lock, flags); | |
233 | blk_plug_device(q); | |
234 | spin_unlock_irqrestore(q->queue_lock, flags); | |
235 | } | |
236 | EXPORT_SYMBOL(blk_plug_device_unlocked); | |
237 | ||
238 | /* | |
239 | * remove the queue from the plugged list, if present. called with | |
240 | * queue lock held and interrupts disabled. | |
241 | */ | |
242 | int blk_remove_plug(struct request_queue *q) | |
243 | { | |
244 | WARN_ON(!irqs_disabled()); | |
245 | ||
246 | if (!queue_flag_test_and_clear(QUEUE_FLAG_PLUGGED, q)) | |
247 | return 0; | |
248 | ||
249 | del_timer(&q->unplug_timer); | |
250 | return 1; | |
251 | } | |
252 | EXPORT_SYMBOL(blk_remove_plug); | |
253 | ||
254 | /* | |
255 | * remove the plug and let it rip.. | |
256 | */ | |
257 | void __generic_unplug_device(struct request_queue *q) | |
258 | { | |
259 | if (unlikely(blk_queue_stopped(q))) | |
260 | return; | |
261 | ||
262 | if (!blk_remove_plug(q)) | |
263 | return; | |
264 | ||
265 | q->request_fn(q); | |
266 | } | |
267 | EXPORT_SYMBOL(__generic_unplug_device); | |
268 | ||
269 | /** | |
270 | * generic_unplug_device - fire a request queue | |
271 | * @q: The &struct request_queue in question | |
272 | * | |
273 | * Description: | |
274 | * Linux uses plugging to build bigger requests queues before letting | |
275 | * the device have at them. If a queue is plugged, the I/O scheduler | |
276 | * is still adding and merging requests on the queue. Once the queue | |
277 | * gets unplugged, the request_fn defined for the queue is invoked and | |
278 | * transfers started. | |
279 | **/ | |
280 | void generic_unplug_device(struct request_queue *q) | |
281 | { | |
282 | if (blk_queue_plugged(q)) { | |
283 | spin_lock_irq(q->queue_lock); | |
284 | __generic_unplug_device(q); | |
285 | spin_unlock_irq(q->queue_lock); | |
286 | } | |
287 | } | |
288 | EXPORT_SYMBOL(generic_unplug_device); | |
289 | ||
290 | static void blk_backing_dev_unplug(struct backing_dev_info *bdi, | |
291 | struct page *page) | |
292 | { | |
293 | struct request_queue *q = bdi->unplug_io_data; | |
294 | ||
295 | blk_unplug(q); | |
296 | } | |
297 | ||
298 | void blk_unplug_work(struct work_struct *work) | |
299 | { | |
300 | struct request_queue *q = | |
301 | container_of(work, struct request_queue, unplug_work); | |
302 | ||
303 | blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL, | |
304 | q->rq.count[READ] + q->rq.count[WRITE]); | |
305 | ||
306 | q->unplug_fn(q); | |
307 | } | |
308 | ||
309 | void blk_unplug_timeout(unsigned long data) | |
310 | { | |
311 | struct request_queue *q = (struct request_queue *)data; | |
312 | ||
313 | blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_TIMER, NULL, | |
314 | q->rq.count[READ] + q->rq.count[WRITE]); | |
315 | ||
316 | kblockd_schedule_work(&q->unplug_work); | |
317 | } | |
318 | ||
319 | void blk_unplug(struct request_queue *q) | |
320 | { | |
321 | /* | |
322 | * devices don't necessarily have an ->unplug_fn defined | |
323 | */ | |
324 | if (q->unplug_fn) { | |
325 | blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL, | |
326 | q->rq.count[READ] + q->rq.count[WRITE]); | |
327 | ||
328 | q->unplug_fn(q); | |
329 | } | |
330 | } | |
331 | EXPORT_SYMBOL(blk_unplug); | |
332 | ||
333 | /** | |
334 | * blk_start_queue - restart a previously stopped queue | |
335 | * @q: The &struct request_queue in question | |
336 | * | |
337 | * Description: | |
338 | * blk_start_queue() will clear the stop flag on the queue, and call | |
339 | * the request_fn for the queue if it was in a stopped state when | |
340 | * entered. Also see blk_stop_queue(). Queue lock must be held. | |
341 | **/ | |
342 | void blk_start_queue(struct request_queue *q) | |
343 | { | |
344 | WARN_ON(!irqs_disabled()); | |
345 | ||
346 | queue_flag_clear(QUEUE_FLAG_STOPPED, q); | |
347 | ||
348 | /* | |
349 | * one level of recursion is ok and is much faster than kicking | |
350 | * the unplug handling | |
351 | */ | |
352 | if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) { | |
353 | q->request_fn(q); | |
354 | queue_flag_clear(QUEUE_FLAG_REENTER, q); | |
355 | } else { | |
356 | blk_plug_device(q); | |
357 | kblockd_schedule_work(&q->unplug_work); | |
358 | } | |
359 | } | |
360 | EXPORT_SYMBOL(blk_start_queue); | |
361 | ||
362 | /** | |
363 | * blk_stop_queue - stop a queue | |
364 | * @q: The &struct request_queue in question | |
365 | * | |
366 | * Description: | |
367 | * The Linux block layer assumes that a block driver will consume all | |
368 | * entries on the request queue when the request_fn strategy is called. | |
369 | * Often this will not happen, because of hardware limitations (queue | |
370 | * depth settings). If a device driver gets a 'queue full' response, | |
371 | * or if it simply chooses not to queue more I/O at one point, it can | |
372 | * call this function to prevent the request_fn from being called until | |
373 | * the driver has signalled it's ready to go again. This happens by calling | |
374 | * blk_start_queue() to restart queue operations. Queue lock must be held. | |
375 | **/ | |
376 | void blk_stop_queue(struct request_queue *q) | |
377 | { | |
378 | blk_remove_plug(q); | |
379 | queue_flag_set(QUEUE_FLAG_STOPPED, q); | |
380 | } | |
381 | EXPORT_SYMBOL(blk_stop_queue); | |
382 | ||
383 | /** | |
384 | * blk_sync_queue - cancel any pending callbacks on a queue | |
385 | * @q: the queue | |
386 | * | |
387 | * Description: | |
388 | * The block layer may perform asynchronous callback activity | |
389 | * on a queue, such as calling the unplug function after a timeout. | |
390 | * A block device may call blk_sync_queue to ensure that any | |
391 | * such activity is cancelled, thus allowing it to release resources | |
392 | * that the callbacks might use. The caller must already have made sure | |
393 | * that its ->make_request_fn will not re-add plugging prior to calling | |
394 | * this function. | |
395 | * | |
396 | */ | |
397 | void blk_sync_queue(struct request_queue *q) | |
398 | { | |
399 | del_timer_sync(&q->unplug_timer); | |
400 | kblockd_flush_work(&q->unplug_work); | |
401 | } | |
402 | EXPORT_SYMBOL(blk_sync_queue); | |
403 | ||
404 | /** | |
405 | * blk_run_queue - run a single device queue | |
406 | * @q: The queue to run | |
407 | */ | |
408 | void __blk_run_queue(struct request_queue *q) | |
409 | { | |
410 | blk_remove_plug(q); | |
411 | ||
412 | /* | |
413 | * Only recurse once to avoid overrunning the stack, let the unplug | |
414 | * handling reinvoke the handler shortly if we already got there. | |
415 | */ | |
416 | if (!elv_queue_empty(q)) { | |
417 | if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) { | |
418 | q->request_fn(q); | |
419 | queue_flag_clear(QUEUE_FLAG_REENTER, q); | |
420 | } else { | |
421 | blk_plug_device(q); | |
422 | kblockd_schedule_work(&q->unplug_work); | |
423 | } | |
424 | } | |
425 | } | |
426 | EXPORT_SYMBOL(__blk_run_queue); | |
427 | ||
428 | /** | |
429 | * blk_run_queue - run a single device queue | |
430 | * @q: The queue to run | |
431 | */ | |
432 | void blk_run_queue(struct request_queue *q) | |
433 | { | |
434 | unsigned long flags; | |
435 | ||
436 | spin_lock_irqsave(q->queue_lock, flags); | |
437 | __blk_run_queue(q); | |
438 | spin_unlock_irqrestore(q->queue_lock, flags); | |
439 | } | |
440 | EXPORT_SYMBOL(blk_run_queue); | |
441 | ||
442 | void blk_put_queue(struct request_queue *q) | |
443 | { | |
444 | kobject_put(&q->kobj); | |
445 | } | |
446 | ||
447 | void blk_cleanup_queue(struct request_queue *q) | |
448 | { | |
449 | mutex_lock(&q->sysfs_lock); | |
450 | queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q); | |
451 | mutex_unlock(&q->sysfs_lock); | |
452 | ||
453 | if (q->elevator) | |
454 | elevator_exit(q->elevator); | |
455 | ||
456 | blk_put_queue(q); | |
457 | } | |
458 | EXPORT_SYMBOL(blk_cleanup_queue); | |
459 | ||
460 | static int blk_init_free_list(struct request_queue *q) | |
461 | { | |
462 | struct request_list *rl = &q->rq; | |
463 | ||
464 | rl->count[READ] = rl->count[WRITE] = 0; | |
465 | rl->starved[READ] = rl->starved[WRITE] = 0; | |
466 | rl->elvpriv = 0; | |
467 | init_waitqueue_head(&rl->wait[READ]); | |
468 | init_waitqueue_head(&rl->wait[WRITE]); | |
469 | ||
470 | rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab, | |
471 | mempool_free_slab, request_cachep, q->node); | |
472 | ||
473 | if (!rl->rq_pool) | |
474 | return -ENOMEM; | |
475 | ||
476 | return 0; | |
477 | } | |
478 | ||
479 | struct request_queue *blk_alloc_queue(gfp_t gfp_mask) | |
480 | { | |
481 | return blk_alloc_queue_node(gfp_mask, -1); | |
482 | } | |
483 | EXPORT_SYMBOL(blk_alloc_queue); | |
484 | ||
485 | struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) | |
486 | { | |
487 | struct request_queue *q; | |
488 | int err; | |
489 | ||
490 | q = kmem_cache_alloc_node(blk_requestq_cachep, | |
491 | gfp_mask | __GFP_ZERO, node_id); | |
492 | if (!q) | |
493 | return NULL; | |
494 | ||
495 | q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug; | |
496 | q->backing_dev_info.unplug_io_data = q; | |
497 | err = bdi_init(&q->backing_dev_info); | |
498 | if (err) { | |
499 | kmem_cache_free(blk_requestq_cachep, q); | |
500 | return NULL; | |
501 | } | |
502 | ||
503 | init_timer(&q->unplug_timer); | |
504 | ||
505 | kobject_init(&q->kobj, &blk_queue_ktype); | |
506 | ||
507 | mutex_init(&q->sysfs_lock); | |
508 | spin_lock_init(&q->__queue_lock); | |
509 | ||
510 | return q; | |
511 | } | |
512 | EXPORT_SYMBOL(blk_alloc_queue_node); | |
513 | ||
514 | /** | |
515 | * blk_init_queue - prepare a request queue for use with a block device | |
516 | * @rfn: The function to be called to process requests that have been | |
517 | * placed on the queue. | |
518 | * @lock: Request queue spin lock | |
519 | * | |
520 | * Description: | |
521 | * If a block device wishes to use the standard request handling procedures, | |
522 | * which sorts requests and coalesces adjacent requests, then it must | |
523 | * call blk_init_queue(). The function @rfn will be called when there | |
524 | * are requests on the queue that need to be processed. If the device | |
525 | * supports plugging, then @rfn may not be called immediately when requests | |
526 | * are available on the queue, but may be called at some time later instead. | |
527 | * Plugged queues are generally unplugged when a buffer belonging to one | |
528 | * of the requests on the queue is needed, or due to memory pressure. | |
529 | * | |
530 | * @rfn is not required, or even expected, to remove all requests off the | |
531 | * queue, but only as many as it can handle at a time. If it does leave | |
532 | * requests on the queue, it is responsible for arranging that the requests | |
533 | * get dealt with eventually. | |
534 | * | |
535 | * The queue spin lock must be held while manipulating the requests on the | |
536 | * request queue; this lock will be taken also from interrupt context, so irq | |
537 | * disabling is needed for it. | |
538 | * | |
539 | * Function returns a pointer to the initialized request queue, or %NULL if | |
540 | * it didn't succeed. | |
541 | * | |
542 | * Note: | |
543 | * blk_init_queue() must be paired with a blk_cleanup_queue() call | |
544 | * when the block device is deactivated (such as at module unload). | |
545 | **/ | |
546 | ||
547 | struct request_queue *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock) | |
548 | { | |
549 | return blk_init_queue_node(rfn, lock, -1); | |
550 | } | |
551 | EXPORT_SYMBOL(blk_init_queue); | |
552 | ||
553 | struct request_queue * | |
554 | blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id) | |
555 | { | |
556 | struct request_queue *q = blk_alloc_queue_node(GFP_KERNEL, node_id); | |
557 | ||
558 | if (!q) | |
559 | return NULL; | |
560 | ||
561 | q->node = node_id; | |
562 | if (blk_init_free_list(q)) { | |
563 | kmem_cache_free(blk_requestq_cachep, q); | |
564 | return NULL; | |
565 | } | |
566 | ||
567 | /* | |
568 | * if caller didn't supply a lock, they get per-queue locking with | |
569 | * our embedded lock | |
570 | */ | |
571 | if (!lock) | |
572 | lock = &q->__queue_lock; | |
573 | ||
574 | q->request_fn = rfn; | |
575 | q->prep_rq_fn = NULL; | |
576 | q->unplug_fn = generic_unplug_device; | |
577 | q->queue_flags = (1 << QUEUE_FLAG_CLUSTER); | |
578 | q->queue_lock = lock; | |
579 | ||
580 | blk_queue_segment_boundary(q, 0xffffffff); | |
581 | ||
582 | blk_queue_make_request(q, __make_request); | |
583 | blk_queue_max_segment_size(q, MAX_SEGMENT_SIZE); | |
584 | ||
585 | blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS); | |
586 | blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS); | |
587 | ||
588 | q->sg_reserved_size = INT_MAX; | |
589 | ||
590 | blk_set_cmd_filter_defaults(&q->cmd_filter); | |
591 | ||
592 | /* | |
593 | * all done | |
594 | */ | |
595 | if (!elevator_init(q, NULL)) { | |
596 | blk_queue_congestion_threshold(q); | |
597 | return q; | |
598 | } | |
599 | ||
600 | blk_put_queue(q); | |
601 | return NULL; | |
602 | } | |
603 | EXPORT_SYMBOL(blk_init_queue_node); | |
604 | ||
605 | int blk_get_queue(struct request_queue *q) | |
606 | { | |
607 | if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) { | |
608 | kobject_get(&q->kobj); | |
609 | return 0; | |
610 | } | |
611 | ||
612 | return 1; | |
613 | } | |
614 | ||
615 | static inline void blk_free_request(struct request_queue *q, struct request *rq) | |
616 | { | |
617 | if (rq->cmd_flags & REQ_ELVPRIV) | |
618 | elv_put_request(q, rq); | |
619 | mempool_free(rq, q->rq.rq_pool); | |
620 | } | |
621 | ||
622 | static struct request * | |
623 | blk_alloc_request(struct request_queue *q, int rw, int priv, gfp_t gfp_mask) | |
624 | { | |
625 | struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask); | |
626 | ||
627 | if (!rq) | |
628 | return NULL; | |
629 | ||
630 | blk_rq_init(q, rq); | |
631 | ||
632 | rq->cmd_flags = rw | REQ_ALLOCED; | |
633 | ||
634 | if (priv) { | |
635 | if (unlikely(elv_set_request(q, rq, gfp_mask))) { | |
636 | mempool_free(rq, q->rq.rq_pool); | |
637 | return NULL; | |
638 | } | |
639 | rq->cmd_flags |= REQ_ELVPRIV; | |
640 | } | |
641 | ||
642 | return rq; | |
643 | } | |
644 | ||
645 | /* | |
646 | * ioc_batching returns true if the ioc is a valid batching request and | |
647 | * should be given priority access to a request. | |
648 | */ | |
649 | static inline int ioc_batching(struct request_queue *q, struct io_context *ioc) | |
650 | { | |
651 | if (!ioc) | |
652 | return 0; | |
653 | ||
654 | /* | |
655 | * Make sure the process is able to allocate at least 1 request | |
656 | * even if the batch times out, otherwise we could theoretically | |
657 | * lose wakeups. | |
658 | */ | |
659 | return ioc->nr_batch_requests == q->nr_batching || | |
660 | (ioc->nr_batch_requests > 0 | |
661 | && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME)); | |
662 | } | |
663 | ||
664 | /* | |
665 | * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This | |
666 | * will cause the process to be a "batcher" on all queues in the system. This | |
667 | * is the behaviour we want though - once it gets a wakeup it should be given | |
668 | * a nice run. | |
669 | */ | |
670 | static void ioc_set_batching(struct request_queue *q, struct io_context *ioc) | |
671 | { | |
672 | if (!ioc || ioc_batching(q, ioc)) | |
673 | return; | |
674 | ||
675 | ioc->nr_batch_requests = q->nr_batching; | |
676 | ioc->last_waited = jiffies; | |
677 | } | |
678 | ||
679 | static void __freed_request(struct request_queue *q, int rw) | |
680 | { | |
681 | struct request_list *rl = &q->rq; | |
682 | ||
683 | if (rl->count[rw] < queue_congestion_off_threshold(q)) | |
684 | blk_clear_queue_congested(q, rw); | |
685 | ||
686 | if (rl->count[rw] + 1 <= q->nr_requests) { | |
687 | if (waitqueue_active(&rl->wait[rw])) | |
688 | wake_up(&rl->wait[rw]); | |
689 | ||
690 | blk_clear_queue_full(q, rw); | |
691 | } | |
692 | } | |
693 | ||
694 | /* | |
695 | * A request has just been released. Account for it, update the full and | |
696 | * congestion status, wake up any waiters. Called under q->queue_lock. | |
697 | */ | |
698 | static void freed_request(struct request_queue *q, int rw, int priv) | |
699 | { | |
700 | struct request_list *rl = &q->rq; | |
701 | ||
702 | rl->count[rw]--; | |
703 | if (priv) | |
704 | rl->elvpriv--; | |
705 | ||
706 | __freed_request(q, rw); | |
707 | ||
708 | if (unlikely(rl->starved[rw ^ 1])) | |
709 | __freed_request(q, rw ^ 1); | |
710 | } | |
711 | ||
712 | #define blkdev_free_rq(list) list_entry((list)->next, struct request, queuelist) | |
713 | /* | |
714 | * Get a free request, queue_lock must be held. | |
715 | * Returns NULL on failure, with queue_lock held. | |
716 | * Returns !NULL on success, with queue_lock *not held*. | |
717 | */ | |
718 | static struct request *get_request(struct request_queue *q, int rw_flags, | |
719 | struct bio *bio, gfp_t gfp_mask) | |
720 | { | |
721 | struct request *rq = NULL; | |
722 | struct request_list *rl = &q->rq; | |
723 | struct io_context *ioc = NULL; | |
724 | const int rw = rw_flags & 0x01; | |
725 | int may_queue, priv; | |
726 | ||
727 | may_queue = elv_may_queue(q, rw_flags); | |
728 | if (may_queue == ELV_MQUEUE_NO) | |
729 | goto rq_starved; | |
730 | ||
731 | if (rl->count[rw]+1 >= queue_congestion_on_threshold(q)) { | |
732 | if (rl->count[rw]+1 >= q->nr_requests) { | |
733 | ioc = current_io_context(GFP_ATOMIC, q->node); | |
734 | /* | |
735 | * The queue will fill after this allocation, so set | |
736 | * it as full, and mark this process as "batching". | |
737 | * This process will be allowed to complete a batch of | |
738 | * requests, others will be blocked. | |
739 | */ | |
740 | if (!blk_queue_full(q, rw)) { | |
741 | ioc_set_batching(q, ioc); | |
742 | blk_set_queue_full(q, rw); | |
743 | } else { | |
744 | if (may_queue != ELV_MQUEUE_MUST | |
745 | && !ioc_batching(q, ioc)) { | |
746 | /* | |
747 | * The queue is full and the allocating | |
748 | * process is not a "batcher", and not | |
749 | * exempted by the IO scheduler | |
750 | */ | |
751 | goto out; | |
752 | } | |
753 | } | |
754 | } | |
755 | blk_set_queue_congested(q, rw); | |
756 | } | |
757 | ||
758 | /* | |
759 | * Only allow batching queuers to allocate up to 50% over the defined | |
760 | * limit of requests, otherwise we could have thousands of requests | |
761 | * allocated with any setting of ->nr_requests | |
762 | */ | |
763 | if (rl->count[rw] >= (3 * q->nr_requests / 2)) | |
764 | goto out; | |
765 | ||
766 | rl->count[rw]++; | |
767 | rl->starved[rw] = 0; | |
768 | ||
769 | priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags); | |
770 | if (priv) | |
771 | rl->elvpriv++; | |
772 | ||
773 | spin_unlock_irq(q->queue_lock); | |
774 | ||
775 | rq = blk_alloc_request(q, rw_flags, priv, gfp_mask); | |
776 | if (unlikely(!rq)) { | |
777 | /* | |
778 | * Allocation failed presumably due to memory. Undo anything | |
779 | * we might have messed up. | |
780 | * | |
781 | * Allocating task should really be put onto the front of the | |
782 | * wait queue, but this is pretty rare. | |
783 | */ | |
784 | spin_lock_irq(q->queue_lock); | |
785 | freed_request(q, rw, priv); | |
786 | ||
787 | /* | |
788 | * in the very unlikely event that allocation failed and no | |
789 | * requests for this direction was pending, mark us starved | |
790 | * so that freeing of a request in the other direction will | |
791 | * notice us. another possible fix would be to split the | |
792 | * rq mempool into READ and WRITE | |
793 | */ | |
794 | rq_starved: | |
795 | if (unlikely(rl->count[rw] == 0)) | |
796 | rl->starved[rw] = 1; | |
797 | ||
798 | goto out; | |
799 | } | |
800 | ||
801 | /* | |
802 | * ioc may be NULL here, and ioc_batching will be false. That's | |
803 | * OK, if the queue is under the request limit then requests need | |
804 | * not count toward the nr_batch_requests limit. There will always | |
805 | * be some limit enforced by BLK_BATCH_TIME. | |
806 | */ | |
807 | if (ioc_batching(q, ioc)) | |
808 | ioc->nr_batch_requests--; | |
809 | ||
810 | blk_add_trace_generic(q, bio, rw, BLK_TA_GETRQ); | |
811 | out: | |
812 | return rq; | |
813 | } | |
814 | ||
815 | /* | |
816 | * No available requests for this queue, unplug the device and wait for some | |
817 | * requests to become available. | |
818 | * | |
819 | * Called with q->queue_lock held, and returns with it unlocked. | |
820 | */ | |
821 | static struct request *get_request_wait(struct request_queue *q, int rw_flags, | |
822 | struct bio *bio) | |
823 | { | |
824 | const int rw = rw_flags & 0x01; | |
825 | struct request *rq; | |
826 | ||
827 | rq = get_request(q, rw_flags, bio, GFP_NOIO); | |
828 | while (!rq) { | |
829 | DEFINE_WAIT(wait); | |
830 | struct io_context *ioc; | |
831 | struct request_list *rl = &q->rq; | |
832 | ||
833 | prepare_to_wait_exclusive(&rl->wait[rw], &wait, | |
834 | TASK_UNINTERRUPTIBLE); | |
835 | ||
836 | blk_add_trace_generic(q, bio, rw, BLK_TA_SLEEPRQ); | |
837 | ||
838 | __generic_unplug_device(q); | |
839 | spin_unlock_irq(q->queue_lock); | |
840 | io_schedule(); | |
841 | ||
842 | /* | |
843 | * After sleeping, we become a "batching" process and | |
844 | * will be able to allocate at least one request, and | |
845 | * up to a big batch of them for a small period time. | |
846 | * See ioc_batching, ioc_set_batching | |
847 | */ | |
848 | ioc = current_io_context(GFP_NOIO, q->node); | |
849 | ioc_set_batching(q, ioc); | |
850 | ||
851 | spin_lock_irq(q->queue_lock); | |
852 | finish_wait(&rl->wait[rw], &wait); | |
853 | ||
854 | rq = get_request(q, rw_flags, bio, GFP_NOIO); | |
855 | }; | |
856 | ||
857 | return rq; | |
858 | } | |
859 | ||
860 | struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask) | |
861 | { | |
862 | struct request *rq; | |
863 | ||
864 | BUG_ON(rw != READ && rw != WRITE); | |
865 | ||
866 | spin_lock_irq(q->queue_lock); | |
867 | if (gfp_mask & __GFP_WAIT) { | |
868 | rq = get_request_wait(q, rw, NULL); | |
869 | } else { | |
870 | rq = get_request(q, rw, NULL, gfp_mask); | |
871 | if (!rq) | |
872 | spin_unlock_irq(q->queue_lock); | |
873 | } | |
874 | /* q->queue_lock is unlocked at this point */ | |
875 | ||
876 | return rq; | |
877 | } | |
878 | EXPORT_SYMBOL(blk_get_request); | |
879 | ||
880 | /** | |
881 | * blk_start_queueing - initiate dispatch of requests to device | |
882 | * @q: request queue to kick into gear | |
883 | * | |
884 | * This is basically a helper to remove the need to know whether a queue | |
885 | * is plugged or not if someone just wants to initiate dispatch of requests | |
886 | * for this queue. | |
887 | * | |
888 | * The queue lock must be held with interrupts disabled. | |
889 | */ | |
890 | void blk_start_queueing(struct request_queue *q) | |
891 | { | |
892 | if (!blk_queue_plugged(q)) | |
893 | q->request_fn(q); | |
894 | else | |
895 | __generic_unplug_device(q); | |
896 | } | |
897 | EXPORT_SYMBOL(blk_start_queueing); | |
898 | ||
899 | /** | |
900 | * blk_requeue_request - put a request back on queue | |
901 | * @q: request queue where request should be inserted | |
902 | * @rq: request to be inserted | |
903 | * | |
904 | * Description: | |
905 | * Drivers often keep queueing requests until the hardware cannot accept | |
906 | * more, when that condition happens we need to put the request back | |
907 | * on the queue. Must be called with queue lock held. | |
908 | */ | |
909 | void blk_requeue_request(struct request_queue *q, struct request *rq) | |
910 | { | |
911 | blk_add_trace_rq(q, rq, BLK_TA_REQUEUE); | |
912 | ||
913 | if (blk_rq_tagged(rq)) | |
914 | blk_queue_end_tag(q, rq); | |
915 | ||
916 | elv_requeue_request(q, rq); | |
917 | } | |
918 | EXPORT_SYMBOL(blk_requeue_request); | |
919 | ||
920 | /** | |
921 | * blk_insert_request - insert a special request into a request queue | |
922 | * @q: request queue where request should be inserted | |
923 | * @rq: request to be inserted | |
924 | * @at_head: insert request at head or tail of queue | |
925 | * @data: private data | |
926 | * | |
927 | * Description: | |
928 | * Many block devices need to execute commands asynchronously, so they don't | |
929 | * block the whole kernel from preemption during request execution. This is | |
930 | * accomplished normally by inserting aritficial requests tagged as | |
931 | * REQ_TYPE_SPECIAL in to the corresponding request queue, and letting them | |
932 | * be scheduled for actual execution by the request queue. | |
933 | * | |
934 | * We have the option of inserting the head or the tail of the queue. | |
935 | * Typically we use the tail for new ioctls and so forth. We use the head | |
936 | * of the queue for things like a QUEUE_FULL message from a device, or a | |
937 | * host that is unable to accept a particular command. | |
938 | */ | |
939 | void blk_insert_request(struct request_queue *q, struct request *rq, | |
940 | int at_head, void *data) | |
941 | { | |
942 | int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK; | |
943 | unsigned long flags; | |
944 | ||
945 | /* | |
946 | * tell I/O scheduler that this isn't a regular read/write (ie it | |
947 | * must not attempt merges on this) and that it acts as a soft | |
948 | * barrier | |
949 | */ | |
950 | rq->cmd_type = REQ_TYPE_SPECIAL; | |
951 | rq->cmd_flags |= REQ_SOFTBARRIER; | |
952 | ||
953 | rq->special = data; | |
954 | ||
955 | spin_lock_irqsave(q->queue_lock, flags); | |
956 | ||
957 | /* | |
958 | * If command is tagged, release the tag | |
959 | */ | |
960 | if (blk_rq_tagged(rq)) | |
961 | blk_queue_end_tag(q, rq); | |
962 | ||
963 | drive_stat_acct(rq, 1); | |
964 | __elv_add_request(q, rq, where, 0); | |
965 | blk_start_queueing(q); | |
966 | spin_unlock_irqrestore(q->queue_lock, flags); | |
967 | } | |
968 | EXPORT_SYMBOL(blk_insert_request); | |
969 | ||
970 | /* | |
971 | * add-request adds a request to the linked list. | |
972 | * queue lock is held and interrupts disabled, as we muck with the | |
973 | * request queue list. | |
974 | */ | |
975 | static inline void add_request(struct request_queue *q, struct request *req) | |
976 | { | |
977 | drive_stat_acct(req, 1); | |
978 | ||
979 | /* | |
980 | * elevator indicated where it wants this request to be | |
981 | * inserted at elevator_merge time | |
982 | */ | |
983 | __elv_add_request(q, req, ELEVATOR_INSERT_SORT, 0); | |
984 | } | |
985 | ||
986 | /* | |
987 | * disk_round_stats() - Round off the performance stats on a struct | |
988 | * disk_stats. | |
989 | * | |
990 | * The average IO queue length and utilisation statistics are maintained | |
991 | * by observing the current state of the queue length and the amount of | |
992 | * time it has been in this state for. | |
993 | * | |
994 | * Normally, that accounting is done on IO completion, but that can result | |
995 | * in more than a second's worth of IO being accounted for within any one | |
996 | * second, leading to >100% utilisation. To deal with that, we call this | |
997 | * function to do a round-off before returning the results when reading | |
998 | * /proc/diskstats. This accounts immediately for all queue usage up to | |
999 | * the current jiffies and restarts the counters again. | |
1000 | */ | |
1001 | void disk_round_stats(int cpu, struct gendisk *disk) | |
1002 | { | |
1003 | unsigned long now = jiffies; | |
1004 | ||
1005 | if (now == disk->stamp) | |
1006 | return; | |
1007 | ||
1008 | if (disk->in_flight) { | |
1009 | disk_stat_add(cpu, disk, time_in_queue, | |
1010 | disk->in_flight * (now - disk->stamp)); | |
1011 | disk_stat_add(cpu, disk, io_ticks, (now - disk->stamp)); | |
1012 | } | |
1013 | disk->stamp = now; | |
1014 | } | |
1015 | EXPORT_SYMBOL_GPL(disk_round_stats); | |
1016 | ||
1017 | void part_round_stats(int cpu, struct hd_struct *part) | |
1018 | { | |
1019 | unsigned long now = jiffies; | |
1020 | ||
1021 | if (now == part->stamp) | |
1022 | return; | |
1023 | ||
1024 | if (part->in_flight) { | |
1025 | part_stat_add(cpu, part, time_in_queue, | |
1026 | part->in_flight * (now - part->stamp)); | |
1027 | part_stat_add(cpu, part, io_ticks, (now - part->stamp)); | |
1028 | } | |
1029 | part->stamp = now; | |
1030 | } | |
1031 | ||
1032 | /* | |
1033 | * queue lock must be held | |
1034 | */ | |
1035 | void __blk_put_request(struct request_queue *q, struct request *req) | |
1036 | { | |
1037 | if (unlikely(!q)) | |
1038 | return; | |
1039 | if (unlikely(--req->ref_count)) | |
1040 | return; | |
1041 | ||
1042 | elv_completed_request(q, req); | |
1043 | ||
1044 | /* | |
1045 | * Request may not have originated from ll_rw_blk. if not, | |
1046 | * it didn't come out of our reserved rq pools | |
1047 | */ | |
1048 | if (req->cmd_flags & REQ_ALLOCED) { | |
1049 | int rw = rq_data_dir(req); | |
1050 | int priv = req->cmd_flags & REQ_ELVPRIV; | |
1051 | ||
1052 | BUG_ON(!list_empty(&req->queuelist)); | |
1053 | BUG_ON(!hlist_unhashed(&req->hash)); | |
1054 | ||
1055 | blk_free_request(q, req); | |
1056 | freed_request(q, rw, priv); | |
1057 | } | |
1058 | } | |
1059 | EXPORT_SYMBOL_GPL(__blk_put_request); | |
1060 | ||
1061 | void blk_put_request(struct request *req) | |
1062 | { | |
1063 | unsigned long flags; | |
1064 | struct request_queue *q = req->q; | |
1065 | ||
1066 | spin_lock_irqsave(q->queue_lock, flags); | |
1067 | __blk_put_request(q, req); | |
1068 | spin_unlock_irqrestore(q->queue_lock, flags); | |
1069 | } | |
1070 | EXPORT_SYMBOL(blk_put_request); | |
1071 | ||
1072 | void init_request_from_bio(struct request *req, struct bio *bio) | |
1073 | { | |
1074 | req->cmd_type = REQ_TYPE_FS; | |
1075 | ||
1076 | /* | |
1077 | * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST) | |
1078 | */ | |
1079 | if (bio_rw_ahead(bio) || bio_failfast(bio)) | |
1080 | req->cmd_flags |= REQ_FAILFAST; | |
1081 | ||
1082 | /* | |
1083 | * REQ_BARRIER implies no merging, but lets make it explicit | |
1084 | */ | |
1085 | if (unlikely(bio_discard(bio))) { | |
1086 | req->cmd_flags |= REQ_DISCARD; | |
1087 | if (bio_barrier(bio)) | |
1088 | req->cmd_flags |= REQ_SOFTBARRIER; | |
1089 | req->q->prepare_discard_fn(req->q, req); | |
1090 | } else if (unlikely(bio_barrier(bio))) | |
1091 | req->cmd_flags |= (REQ_HARDBARRIER | REQ_NOMERGE); | |
1092 | ||
1093 | if (bio_sync(bio)) | |
1094 | req->cmd_flags |= REQ_RW_SYNC; | |
1095 | if (bio_rw_meta(bio)) | |
1096 | req->cmd_flags |= REQ_RW_META; | |
1097 | ||
1098 | req->errors = 0; | |
1099 | req->hard_sector = req->sector = bio->bi_sector; | |
1100 | req->ioprio = bio_prio(bio); | |
1101 | req->start_time = jiffies; | |
1102 | blk_rq_bio_prep(req->q, req, bio); | |
1103 | } | |
1104 | ||
1105 | static int __make_request(struct request_queue *q, struct bio *bio) | |
1106 | { | |
1107 | struct request *req; | |
1108 | int el_ret, nr_sectors, barrier, discard, err; | |
1109 | const unsigned short prio = bio_prio(bio); | |
1110 | const int sync = bio_sync(bio); | |
1111 | int rw_flags; | |
1112 | ||
1113 | nr_sectors = bio_sectors(bio); | |
1114 | ||
1115 | /* | |
1116 | * low level driver can indicate that it wants pages above a | |
1117 | * certain limit bounced to low memory (ie for highmem, or even | |
1118 | * ISA dma in theory) | |
1119 | */ | |
1120 | blk_queue_bounce(q, &bio); | |
1121 | ||
1122 | barrier = bio_barrier(bio); | |
1123 | if (unlikely(barrier) && bio_has_data(bio) && | |
1124 | (q->next_ordered == QUEUE_ORDERED_NONE)) { | |
1125 | err = -EOPNOTSUPP; | |
1126 | goto end_io; | |
1127 | } | |
1128 | ||
1129 | discard = bio_discard(bio); | |
1130 | if (unlikely(discard) && !q->prepare_discard_fn) { | |
1131 | err = -EOPNOTSUPP; | |
1132 | goto end_io; | |
1133 | } | |
1134 | ||
1135 | spin_lock_irq(q->queue_lock); | |
1136 | ||
1137 | if (unlikely(barrier) || elv_queue_empty(q)) | |
1138 | goto get_rq; | |
1139 | ||
1140 | el_ret = elv_merge(q, &req, bio); | |
1141 | switch (el_ret) { | |
1142 | case ELEVATOR_BACK_MERGE: | |
1143 | BUG_ON(!rq_mergeable(req)); | |
1144 | ||
1145 | if (!ll_back_merge_fn(q, req, bio)) | |
1146 | break; | |
1147 | ||
1148 | blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE); | |
1149 | ||
1150 | req->biotail->bi_next = bio; | |
1151 | req->biotail = bio; | |
1152 | req->nr_sectors = req->hard_nr_sectors += nr_sectors; | |
1153 | req->ioprio = ioprio_best(req->ioprio, prio); | |
1154 | drive_stat_acct(req, 0); | |
1155 | if (!attempt_back_merge(q, req)) | |
1156 | elv_merged_request(q, req, el_ret); | |
1157 | goto out; | |
1158 | ||
1159 | case ELEVATOR_FRONT_MERGE: | |
1160 | BUG_ON(!rq_mergeable(req)); | |
1161 | ||
1162 | if (!ll_front_merge_fn(q, req, bio)) | |
1163 | break; | |
1164 | ||
1165 | blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE); | |
1166 | ||
1167 | bio->bi_next = req->bio; | |
1168 | req->bio = bio; | |
1169 | ||
1170 | /* | |
1171 | * may not be valid. if the low level driver said | |
1172 | * it didn't need a bounce buffer then it better | |
1173 | * not touch req->buffer either... | |
1174 | */ | |
1175 | req->buffer = bio_data(bio); | |
1176 | req->current_nr_sectors = bio_cur_sectors(bio); | |
1177 | req->hard_cur_sectors = req->current_nr_sectors; | |
1178 | req->sector = req->hard_sector = bio->bi_sector; | |
1179 | req->nr_sectors = req->hard_nr_sectors += nr_sectors; | |
1180 | req->ioprio = ioprio_best(req->ioprio, prio); | |
1181 | drive_stat_acct(req, 0); | |
1182 | if (!attempt_front_merge(q, req)) | |
1183 | elv_merged_request(q, req, el_ret); | |
1184 | goto out; | |
1185 | ||
1186 | /* ELV_NO_MERGE: elevator says don't/can't merge. */ | |
1187 | default: | |
1188 | ; | |
1189 | } | |
1190 | ||
1191 | get_rq: | |
1192 | /* | |
1193 | * This sync check and mask will be re-done in init_request_from_bio(), | |
1194 | * but we need to set it earlier to expose the sync flag to the | |
1195 | * rq allocator and io schedulers. | |
1196 | */ | |
1197 | rw_flags = bio_data_dir(bio); | |
1198 | if (sync) | |
1199 | rw_flags |= REQ_RW_SYNC; | |
1200 | ||
1201 | /* | |
1202 | * Grab a free request. This is might sleep but can not fail. | |
1203 | * Returns with the queue unlocked. | |
1204 | */ | |
1205 | req = get_request_wait(q, rw_flags, bio); | |
1206 | ||
1207 | /* | |
1208 | * After dropping the lock and possibly sleeping here, our request | |
1209 | * may now be mergeable after it had proven unmergeable (above). | |
1210 | * We don't worry about that case for efficiency. It won't happen | |
1211 | * often, and the elevators are able to handle it. | |
1212 | */ | |
1213 | init_request_from_bio(req, bio); | |
1214 | ||
1215 | spin_lock_irq(q->queue_lock); | |
1216 | if (elv_queue_empty(q)) | |
1217 | blk_plug_device(q); | |
1218 | add_request(q, req); | |
1219 | out: | |
1220 | if (sync) | |
1221 | __generic_unplug_device(q); | |
1222 | ||
1223 | spin_unlock_irq(q->queue_lock); | |
1224 | return 0; | |
1225 | ||
1226 | end_io: | |
1227 | bio_endio(bio, err); | |
1228 | return 0; | |
1229 | } | |
1230 | ||
1231 | /* | |
1232 | * If bio->bi_dev is a partition, remap the location | |
1233 | */ | |
1234 | static inline void blk_partition_remap(struct bio *bio) | |
1235 | { | |
1236 | struct block_device *bdev = bio->bi_bdev; | |
1237 | ||
1238 | if (bio_sectors(bio) && bdev != bdev->bd_contains) { | |
1239 | struct hd_struct *p = bdev->bd_part; | |
1240 | ||
1241 | bio->bi_sector += p->start_sect; | |
1242 | bio->bi_bdev = bdev->bd_contains; | |
1243 | ||
1244 | blk_add_trace_remap(bdev_get_queue(bio->bi_bdev), bio, | |
1245 | bdev->bd_dev, bio->bi_sector, | |
1246 | bio->bi_sector - p->start_sect); | |
1247 | } | |
1248 | } | |
1249 | ||
1250 | static void handle_bad_sector(struct bio *bio) | |
1251 | { | |
1252 | char b[BDEVNAME_SIZE]; | |
1253 | ||
1254 | printk(KERN_INFO "attempt to access beyond end of device\n"); | |
1255 | printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n", | |
1256 | bdevname(bio->bi_bdev, b), | |
1257 | bio->bi_rw, | |
1258 | (unsigned long long)bio->bi_sector + bio_sectors(bio), | |
1259 | (long long)(bio->bi_bdev->bd_inode->i_size >> 9)); | |
1260 | ||
1261 | set_bit(BIO_EOF, &bio->bi_flags); | |
1262 | } | |
1263 | ||
1264 | #ifdef CONFIG_FAIL_MAKE_REQUEST | |
1265 | ||
1266 | static DECLARE_FAULT_ATTR(fail_make_request); | |
1267 | ||
1268 | static int __init setup_fail_make_request(char *str) | |
1269 | { | |
1270 | return setup_fault_attr(&fail_make_request, str); | |
1271 | } | |
1272 | __setup("fail_make_request=", setup_fail_make_request); | |
1273 | ||
1274 | static int should_fail_request(struct bio *bio) | |
1275 | { | |
1276 | struct hd_struct *part = bio->bi_bdev->bd_part; | |
1277 | ||
1278 | if (part_to_disk(part)->part0.make_it_fail || part->make_it_fail) | |
1279 | return should_fail(&fail_make_request, bio->bi_size); | |
1280 | ||
1281 | return 0; | |
1282 | } | |
1283 | ||
1284 | static int __init fail_make_request_debugfs(void) | |
1285 | { | |
1286 | return init_fault_attr_dentries(&fail_make_request, | |
1287 | "fail_make_request"); | |
1288 | } | |
1289 | ||
1290 | late_initcall(fail_make_request_debugfs); | |
1291 | ||
1292 | #else /* CONFIG_FAIL_MAKE_REQUEST */ | |
1293 | ||
1294 | static inline int should_fail_request(struct bio *bio) | |
1295 | { | |
1296 | return 0; | |
1297 | } | |
1298 | ||
1299 | #endif /* CONFIG_FAIL_MAKE_REQUEST */ | |
1300 | ||
1301 | /* | |
1302 | * Check whether this bio extends beyond the end of the device. | |
1303 | */ | |
1304 | static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors) | |
1305 | { | |
1306 | sector_t maxsector; | |
1307 | ||
1308 | if (!nr_sectors) | |
1309 | return 0; | |
1310 | ||
1311 | /* Test device or partition size, when known. */ | |
1312 | maxsector = bio->bi_bdev->bd_inode->i_size >> 9; | |
1313 | if (maxsector) { | |
1314 | sector_t sector = bio->bi_sector; | |
1315 | ||
1316 | if (maxsector < nr_sectors || maxsector - nr_sectors < sector) { | |
1317 | /* | |
1318 | * This may well happen - the kernel calls bread() | |
1319 | * without checking the size of the device, e.g., when | |
1320 | * mounting a device. | |
1321 | */ | |
1322 | handle_bad_sector(bio); | |
1323 | return 1; | |
1324 | } | |
1325 | } | |
1326 | ||
1327 | return 0; | |
1328 | } | |
1329 | ||
1330 | /** | |
1331 | * generic_make_request - hand a buffer to its device driver for I/O | |
1332 | * @bio: The bio describing the location in memory and on the device. | |
1333 | * | |
1334 | * generic_make_request() is used to make I/O requests of block | |
1335 | * devices. It is passed a &struct bio, which describes the I/O that needs | |
1336 | * to be done. | |
1337 | * | |
1338 | * generic_make_request() does not return any status. The | |
1339 | * success/failure status of the request, along with notification of | |
1340 | * completion, is delivered asynchronously through the bio->bi_end_io | |
1341 | * function described (one day) else where. | |
1342 | * | |
1343 | * The caller of generic_make_request must make sure that bi_io_vec | |
1344 | * are set to describe the memory buffer, and that bi_dev and bi_sector are | |
1345 | * set to describe the device address, and the | |
1346 | * bi_end_io and optionally bi_private are set to describe how | |
1347 | * completion notification should be signaled. | |
1348 | * | |
1349 | * generic_make_request and the drivers it calls may use bi_next if this | |
1350 | * bio happens to be merged with someone else, and may change bi_dev and | |
1351 | * bi_sector for remaps as it sees fit. So the values of these fields | |
1352 | * should NOT be depended on after the call to generic_make_request. | |
1353 | */ | |
1354 | static inline void __generic_make_request(struct bio *bio) | |
1355 | { | |
1356 | struct request_queue *q; | |
1357 | sector_t old_sector; | |
1358 | int ret, nr_sectors = bio_sectors(bio); | |
1359 | dev_t old_dev; | |
1360 | int err = -EIO; | |
1361 | ||
1362 | might_sleep(); | |
1363 | ||
1364 | if (bio_check_eod(bio, nr_sectors)) | |
1365 | goto end_io; | |
1366 | ||
1367 | /* | |
1368 | * Resolve the mapping until finished. (drivers are | |
1369 | * still free to implement/resolve their own stacking | |
1370 | * by explicitly returning 0) | |
1371 | * | |
1372 | * NOTE: we don't repeat the blk_size check for each new device. | |
1373 | * Stacking drivers are expected to know what they are doing. | |
1374 | */ | |
1375 | old_sector = -1; | |
1376 | old_dev = 0; | |
1377 | do { | |
1378 | char b[BDEVNAME_SIZE]; | |
1379 | ||
1380 | q = bdev_get_queue(bio->bi_bdev); | |
1381 | if (!q) { | |
1382 | printk(KERN_ERR | |
1383 | "generic_make_request: Trying to access " | |
1384 | "nonexistent block-device %s (%Lu)\n", | |
1385 | bdevname(bio->bi_bdev, b), | |
1386 | (long long) bio->bi_sector); | |
1387 | end_io: | |
1388 | bio_endio(bio, err); | |
1389 | break; | |
1390 | } | |
1391 | ||
1392 | if (unlikely(nr_sectors > q->max_hw_sectors)) { | |
1393 | printk(KERN_ERR "bio too big device %s (%u > %u)\n", | |
1394 | bdevname(bio->bi_bdev, b), | |
1395 | bio_sectors(bio), | |
1396 | q->max_hw_sectors); | |
1397 | goto end_io; | |
1398 | } | |
1399 | ||
1400 | if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) | |
1401 | goto end_io; | |
1402 | ||
1403 | if (should_fail_request(bio)) | |
1404 | goto end_io; | |
1405 | ||
1406 | /* | |
1407 | * If this device has partitions, remap block n | |
1408 | * of partition p to block n+start(p) of the disk. | |
1409 | */ | |
1410 | blk_partition_remap(bio); | |
1411 | ||
1412 | if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) | |
1413 | goto end_io; | |
1414 | ||
1415 | if (old_sector != -1) | |
1416 | blk_add_trace_remap(q, bio, old_dev, bio->bi_sector, | |
1417 | old_sector); | |
1418 | ||
1419 | blk_add_trace_bio(q, bio, BLK_TA_QUEUE); | |
1420 | ||
1421 | old_sector = bio->bi_sector; | |
1422 | old_dev = bio->bi_bdev->bd_dev; | |
1423 | ||
1424 | if (bio_check_eod(bio, nr_sectors)) | |
1425 | goto end_io; | |
1426 | if ((bio_empty_barrier(bio) && !q->prepare_flush_fn) || | |
1427 | (bio_discard(bio) && !q->prepare_discard_fn)) { | |
1428 | err = -EOPNOTSUPP; | |
1429 | goto end_io; | |
1430 | } | |
1431 | ||
1432 | ret = q->make_request_fn(q, bio); | |
1433 | } while (ret); | |
1434 | } | |
1435 | ||
1436 | /* | |
1437 | * We only want one ->make_request_fn to be active at a time, | |
1438 | * else stack usage with stacked devices could be a problem. | |
1439 | * So use current->bio_{list,tail} to keep a list of requests | |
1440 | * submited by a make_request_fn function. | |
1441 | * current->bio_tail is also used as a flag to say if | |
1442 | * generic_make_request is currently active in this task or not. | |
1443 | * If it is NULL, then no make_request is active. If it is non-NULL, | |
1444 | * then a make_request is active, and new requests should be added | |
1445 | * at the tail | |
1446 | */ | |
1447 | void generic_make_request(struct bio *bio) | |
1448 | { | |
1449 | if (current->bio_tail) { | |
1450 | /* make_request is active */ | |
1451 | *(current->bio_tail) = bio; | |
1452 | bio->bi_next = NULL; | |
1453 | current->bio_tail = &bio->bi_next; | |
1454 | return; | |
1455 | } | |
1456 | /* following loop may be a bit non-obvious, and so deserves some | |
1457 | * explanation. | |
1458 | * Before entering the loop, bio->bi_next is NULL (as all callers | |
1459 | * ensure that) so we have a list with a single bio. | |
1460 | * We pretend that we have just taken it off a longer list, so | |
1461 | * we assign bio_list to the next (which is NULL) and bio_tail | |
1462 | * to &bio_list, thus initialising the bio_list of new bios to be | |
1463 | * added. __generic_make_request may indeed add some more bios | |
1464 | * through a recursive call to generic_make_request. If it | |
1465 | * did, we find a non-NULL value in bio_list and re-enter the loop | |
1466 | * from the top. In this case we really did just take the bio | |
1467 | * of the top of the list (no pretending) and so fixup bio_list and | |
1468 | * bio_tail or bi_next, and call into __generic_make_request again. | |
1469 | * | |
1470 | * The loop was structured like this to make only one call to | |
1471 | * __generic_make_request (which is important as it is large and | |
1472 | * inlined) and to keep the structure simple. | |
1473 | */ | |
1474 | BUG_ON(bio->bi_next); | |
1475 | do { | |
1476 | current->bio_list = bio->bi_next; | |
1477 | if (bio->bi_next == NULL) | |
1478 | current->bio_tail = ¤t->bio_list; | |
1479 | else | |
1480 | bio->bi_next = NULL; | |
1481 | __generic_make_request(bio); | |
1482 | bio = current->bio_list; | |
1483 | } while (bio); | |
1484 | current->bio_tail = NULL; /* deactivate */ | |
1485 | } | |
1486 | EXPORT_SYMBOL(generic_make_request); | |
1487 | ||
1488 | /** | |
1489 | * submit_bio - submit a bio to the block device layer for I/O | |
1490 | * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead) | |
1491 | * @bio: The &struct bio which describes the I/O | |
1492 | * | |
1493 | * submit_bio() is very similar in purpose to generic_make_request(), and | |
1494 | * uses that function to do most of the work. Both are fairly rough | |
1495 | * interfaces; @bio must be presetup and ready for I/O. | |
1496 | * | |
1497 | */ | |
1498 | void submit_bio(int rw, struct bio *bio) | |
1499 | { | |
1500 | int count = bio_sectors(bio); | |
1501 | ||
1502 | bio->bi_rw |= rw; | |
1503 | ||
1504 | /* | |
1505 | * If it's a regular read/write or a barrier with data attached, | |
1506 | * go through the normal accounting stuff before submission. | |
1507 | */ | |
1508 | if (bio_has_data(bio)) { | |
1509 | if (rw & WRITE) { | |
1510 | count_vm_events(PGPGOUT, count); | |
1511 | } else { | |
1512 | task_io_account_read(bio->bi_size); | |
1513 | count_vm_events(PGPGIN, count); | |
1514 | } | |
1515 | ||
1516 | if (unlikely(block_dump)) { | |
1517 | char b[BDEVNAME_SIZE]; | |
1518 | printk(KERN_DEBUG "%s(%d): %s block %Lu on %s\n", | |
1519 | current->comm, task_pid_nr(current), | |
1520 | (rw & WRITE) ? "WRITE" : "READ", | |
1521 | (unsigned long long)bio->bi_sector, | |
1522 | bdevname(bio->bi_bdev, b)); | |
1523 | } | |
1524 | } | |
1525 | ||
1526 | generic_make_request(bio); | |
1527 | } | |
1528 | EXPORT_SYMBOL(submit_bio); | |
1529 | ||
1530 | /** | |
1531 | * __end_that_request_first - end I/O on a request | |
1532 | * @req: the request being processed | |
1533 | * @error: %0 for success, < %0 for error | |
1534 | * @nr_bytes: number of bytes to complete | |
1535 | * | |
1536 | * Description: | |
1537 | * Ends I/O on a number of bytes attached to @req, and sets it up | |
1538 | * for the next range of segments (if any) in the cluster. | |
1539 | * | |
1540 | * Return: | |
1541 | * %0 - we are done with this request, call end_that_request_last() | |
1542 | * %1 - still buffers pending for this request | |
1543 | **/ | |
1544 | static int __end_that_request_first(struct request *req, int error, | |
1545 | int nr_bytes) | |
1546 | { | |
1547 | int total_bytes, bio_nbytes, next_idx = 0; | |
1548 | struct bio *bio; | |
1549 | ||
1550 | blk_add_trace_rq(req->q, req, BLK_TA_COMPLETE); | |
1551 | ||
1552 | /* | |
1553 | * for a REQ_TYPE_BLOCK_PC request, we want to carry any eventual | |
1554 | * sense key with us all the way through | |
1555 | */ | |
1556 | if (!blk_pc_request(req)) | |
1557 | req->errors = 0; | |
1558 | ||
1559 | if (error && (blk_fs_request(req) && !(req->cmd_flags & REQ_QUIET))) { | |
1560 | printk(KERN_ERR "end_request: I/O error, dev %s, sector %llu\n", | |
1561 | req->rq_disk ? req->rq_disk->disk_name : "?", | |
1562 | (unsigned long long)req->sector); | |
1563 | } | |
1564 | ||
1565 | if (blk_fs_request(req) && req->rq_disk) { | |
1566 | const int rw = rq_data_dir(req); | |
1567 | struct hd_struct *part; | |
1568 | int cpu; | |
1569 | ||
1570 | cpu = disk_stat_lock(); | |
1571 | part = disk_map_sector_rcu(req->rq_disk, req->sector); | |
1572 | all_stat_add(cpu, req->rq_disk, part, sectors[rw], | |
1573 | nr_bytes >> 9, req->sector); | |
1574 | disk_stat_unlock(); | |
1575 | } | |
1576 | ||
1577 | total_bytes = bio_nbytes = 0; | |
1578 | while ((bio = req->bio) != NULL) { | |
1579 | int nbytes; | |
1580 | ||
1581 | /* | |
1582 | * For an empty barrier request, the low level driver must | |
1583 | * store a potential error location in ->sector. We pass | |
1584 | * that back up in ->bi_sector. | |
1585 | */ | |
1586 | if (blk_empty_barrier(req)) | |
1587 | bio->bi_sector = req->sector; | |
1588 | ||
1589 | if (nr_bytes >= bio->bi_size) { | |
1590 | req->bio = bio->bi_next; | |
1591 | nbytes = bio->bi_size; | |
1592 | req_bio_endio(req, bio, nbytes, error); | |
1593 | next_idx = 0; | |
1594 | bio_nbytes = 0; | |
1595 | } else { | |
1596 | int idx = bio->bi_idx + next_idx; | |
1597 | ||
1598 | if (unlikely(bio->bi_idx >= bio->bi_vcnt)) { | |
1599 | blk_dump_rq_flags(req, "__end_that"); | |
1600 | printk(KERN_ERR "%s: bio idx %d >= vcnt %d\n", | |
1601 | __func__, bio->bi_idx, bio->bi_vcnt); | |
1602 | break; | |
1603 | } | |
1604 | ||
1605 | nbytes = bio_iovec_idx(bio, idx)->bv_len; | |
1606 | BIO_BUG_ON(nbytes > bio->bi_size); | |
1607 | ||
1608 | /* | |
1609 | * not a complete bvec done | |
1610 | */ | |
1611 | if (unlikely(nbytes > nr_bytes)) { | |
1612 | bio_nbytes += nr_bytes; | |
1613 | total_bytes += nr_bytes; | |
1614 | break; | |
1615 | } | |
1616 | ||
1617 | /* | |
1618 | * advance to the next vector | |
1619 | */ | |
1620 | next_idx++; | |
1621 | bio_nbytes += nbytes; | |
1622 | } | |
1623 | ||
1624 | total_bytes += nbytes; | |
1625 | nr_bytes -= nbytes; | |
1626 | ||
1627 | bio = req->bio; | |
1628 | if (bio) { | |
1629 | /* | |
1630 | * end more in this run, or just return 'not-done' | |
1631 | */ | |
1632 | if (unlikely(nr_bytes <= 0)) | |
1633 | break; | |
1634 | } | |
1635 | } | |
1636 | ||
1637 | /* | |
1638 | * completely done | |
1639 | */ | |
1640 | if (!req->bio) | |
1641 | return 0; | |
1642 | ||
1643 | /* | |
1644 | * if the request wasn't completed, update state | |
1645 | */ | |
1646 | if (bio_nbytes) { | |
1647 | req_bio_endio(req, bio, bio_nbytes, error); | |
1648 | bio->bi_idx += next_idx; | |
1649 | bio_iovec(bio)->bv_offset += nr_bytes; | |
1650 | bio_iovec(bio)->bv_len -= nr_bytes; | |
1651 | } | |
1652 | ||
1653 | blk_recalc_rq_sectors(req, total_bytes >> 9); | |
1654 | blk_recalc_rq_segments(req); | |
1655 | return 1; | |
1656 | } | |
1657 | ||
1658 | /* | |
1659 | * splice the completion data to a local structure and hand off to | |
1660 | * process_completion_queue() to complete the requests | |
1661 | */ | |
1662 | static void blk_done_softirq(struct softirq_action *h) | |
1663 | { | |
1664 | struct list_head *cpu_list, local_list; | |
1665 | ||
1666 | local_irq_disable(); | |
1667 | cpu_list = &__get_cpu_var(blk_cpu_done); | |
1668 | list_replace_init(cpu_list, &local_list); | |
1669 | local_irq_enable(); | |
1670 | ||
1671 | while (!list_empty(&local_list)) { | |
1672 | struct request *rq; | |
1673 | ||
1674 | rq = list_entry(local_list.next, struct request, donelist); | |
1675 | list_del_init(&rq->donelist); | |
1676 | rq->q->softirq_done_fn(rq); | |
1677 | } | |
1678 | } | |
1679 | ||
1680 | static int __cpuinit blk_cpu_notify(struct notifier_block *self, | |
1681 | unsigned long action, void *hcpu) | |
1682 | { | |
1683 | /* | |
1684 | * If a CPU goes away, splice its entries to the current CPU | |
1685 | * and trigger a run of the softirq | |
1686 | */ | |
1687 | if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { | |
1688 | int cpu = (unsigned long) hcpu; | |
1689 | ||
1690 | local_irq_disable(); | |
1691 | list_splice_init(&per_cpu(blk_cpu_done, cpu), | |
1692 | &__get_cpu_var(blk_cpu_done)); | |
1693 | raise_softirq_irqoff(BLOCK_SOFTIRQ); | |
1694 | local_irq_enable(); | |
1695 | } | |
1696 | ||
1697 | return NOTIFY_OK; | |
1698 | } | |
1699 | ||
1700 | ||
1701 | static struct notifier_block blk_cpu_notifier __cpuinitdata = { | |
1702 | .notifier_call = blk_cpu_notify, | |
1703 | }; | |
1704 | ||
1705 | /** | |
1706 | * blk_complete_request - end I/O on a request | |
1707 | * @req: the request being processed | |
1708 | * | |
1709 | * Description: | |
1710 | * Ends all I/O on a request. It does not handle partial completions, | |
1711 | * unless the driver actually implements this in its completion callback | |
1712 | * through requeueing. The actual completion happens out-of-order, | |
1713 | * through a softirq handler. The user must have registered a completion | |
1714 | * callback through blk_queue_softirq_done(). | |
1715 | **/ | |
1716 | ||
1717 | void blk_complete_request(struct request *req) | |
1718 | { | |
1719 | struct list_head *cpu_list; | |
1720 | unsigned long flags; | |
1721 | ||
1722 | BUG_ON(!req->q->softirq_done_fn); | |
1723 | ||
1724 | local_irq_save(flags); | |
1725 | ||
1726 | cpu_list = &__get_cpu_var(blk_cpu_done); | |
1727 | list_add_tail(&req->donelist, cpu_list); | |
1728 | raise_softirq_irqoff(BLOCK_SOFTIRQ); | |
1729 | ||
1730 | local_irq_restore(flags); | |
1731 | } | |
1732 | EXPORT_SYMBOL(blk_complete_request); | |
1733 | ||
1734 | /* | |
1735 | * queue lock must be held | |
1736 | */ | |
1737 | static void end_that_request_last(struct request *req, int error) | |
1738 | { | |
1739 | struct gendisk *disk = req->rq_disk; | |
1740 | ||
1741 | if (blk_rq_tagged(req)) | |
1742 | blk_queue_end_tag(req->q, req); | |
1743 | ||
1744 | if (blk_queued_rq(req)) | |
1745 | blkdev_dequeue_request(req); | |
1746 | ||
1747 | if (unlikely(laptop_mode) && blk_fs_request(req)) | |
1748 | laptop_io_completion(); | |
1749 | ||
1750 | /* | |
1751 | * Account IO completion. bar_rq isn't accounted as a normal | |
1752 | * IO on queueing nor completion. Accounting the containing | |
1753 | * request is enough. | |
1754 | */ | |
1755 | if (disk && blk_fs_request(req) && req != &req->q->bar_rq) { | |
1756 | unsigned long duration = jiffies - req->start_time; | |
1757 | const int rw = rq_data_dir(req); | |
1758 | struct hd_struct *part; | |
1759 | int cpu; | |
1760 | ||
1761 | cpu = disk_stat_lock(); | |
1762 | part = disk_map_sector_rcu(disk, req->sector); | |
1763 | ||
1764 | all_stat_inc(cpu, disk, part, ios[rw], req->sector); | |
1765 | all_stat_add(cpu, disk, part, ticks[rw], duration, req->sector); | |
1766 | disk_round_stats(cpu, disk); | |
1767 | disk->in_flight--; | |
1768 | if (part) { | |
1769 | part_round_stats(cpu, part); | |
1770 | part->in_flight--; | |
1771 | } | |
1772 | ||
1773 | disk_stat_unlock(); | |
1774 | } | |
1775 | ||
1776 | if (req->end_io) | |
1777 | req->end_io(req, error); | |
1778 | else { | |
1779 | if (blk_bidi_rq(req)) | |
1780 | __blk_put_request(req->next_rq->q, req->next_rq); | |
1781 | ||
1782 | __blk_put_request(req->q, req); | |
1783 | } | |
1784 | } | |
1785 | ||
1786 | static inline void __end_request(struct request *rq, int uptodate, | |
1787 | unsigned int nr_bytes) | |
1788 | { | |
1789 | int error = 0; | |
1790 | ||
1791 | if (uptodate <= 0) | |
1792 | error = uptodate ? uptodate : -EIO; | |
1793 | ||
1794 | __blk_end_request(rq, error, nr_bytes); | |
1795 | } | |
1796 | ||
1797 | /** | |
1798 | * blk_rq_bytes - Returns bytes left to complete in the entire request | |
1799 | * @rq: the request being processed | |
1800 | **/ | |
1801 | unsigned int blk_rq_bytes(struct request *rq) | |
1802 | { | |
1803 | if (blk_fs_request(rq)) | |
1804 | return rq->hard_nr_sectors << 9; | |
1805 | ||
1806 | return rq->data_len; | |
1807 | } | |
1808 | EXPORT_SYMBOL_GPL(blk_rq_bytes); | |
1809 | ||
1810 | /** | |
1811 | * blk_rq_cur_bytes - Returns bytes left to complete in the current segment | |
1812 | * @rq: the request being processed | |
1813 | **/ | |
1814 | unsigned int blk_rq_cur_bytes(struct request *rq) | |
1815 | { | |
1816 | if (blk_fs_request(rq)) | |
1817 | return rq->current_nr_sectors << 9; | |
1818 | ||
1819 | if (rq->bio) | |
1820 | return rq->bio->bi_size; | |
1821 | ||
1822 | return rq->data_len; | |
1823 | } | |
1824 | EXPORT_SYMBOL_GPL(blk_rq_cur_bytes); | |
1825 | ||
1826 | /** | |
1827 | * end_queued_request - end all I/O on a queued request | |
1828 | * @rq: the request being processed | |
1829 | * @uptodate: error value or %0/%1 uptodate flag | |
1830 | * | |
1831 | * Description: | |
1832 | * Ends all I/O on a request, and removes it from the block layer queues. | |
1833 | * Not suitable for normal I/O completion, unless the driver still has | |
1834 | * the request attached to the block layer. | |
1835 | * | |
1836 | **/ | |
1837 | void end_queued_request(struct request *rq, int uptodate) | |
1838 | { | |
1839 | __end_request(rq, uptodate, blk_rq_bytes(rq)); | |
1840 | } | |
1841 | EXPORT_SYMBOL(end_queued_request); | |
1842 | ||
1843 | /** | |
1844 | * end_dequeued_request - end all I/O on a dequeued request | |
1845 | * @rq: the request being processed | |
1846 | * @uptodate: error value or %0/%1 uptodate flag | |
1847 | * | |
1848 | * Description: | |
1849 | * Ends all I/O on a request. The request must already have been | |
1850 | * dequeued using blkdev_dequeue_request(), as is normally the case | |
1851 | * for most drivers. | |
1852 | * | |
1853 | **/ | |
1854 | void end_dequeued_request(struct request *rq, int uptodate) | |
1855 | { | |
1856 | __end_request(rq, uptodate, blk_rq_bytes(rq)); | |
1857 | } | |
1858 | EXPORT_SYMBOL(end_dequeued_request); | |
1859 | ||
1860 | ||
1861 | /** | |
1862 | * end_request - end I/O on the current segment of the request | |
1863 | * @req: the request being processed | |
1864 | * @uptodate: error value or %0/%1 uptodate flag | |
1865 | * | |
1866 | * Description: | |
1867 | * Ends I/O on the current segment of a request. If that is the only | |
1868 | * remaining segment, the request is also completed and freed. | |
1869 | * | |
1870 | * This is a remnant of how older block drivers handled I/O completions. | |
1871 | * Modern drivers typically end I/O on the full request in one go, unless | |
1872 | * they have a residual value to account for. For that case this function | |
1873 | * isn't really useful, unless the residual just happens to be the | |
1874 | * full current segment. In other words, don't use this function in new | |
1875 | * code. Either use end_request_completely(), or the | |
1876 | * end_that_request_chunk() (along with end_that_request_last()) for | |
1877 | * partial completions. | |
1878 | * | |
1879 | **/ | |
1880 | void end_request(struct request *req, int uptodate) | |
1881 | { | |
1882 | __end_request(req, uptodate, req->hard_cur_sectors << 9); | |
1883 | } | |
1884 | EXPORT_SYMBOL(end_request); | |
1885 | ||
1886 | /** | |
1887 | * blk_end_io - Generic end_io function to complete a request. | |
1888 | * @rq: the request being processed | |
1889 | * @error: %0 for success, < %0 for error | |
1890 | * @nr_bytes: number of bytes to complete @rq | |
1891 | * @bidi_bytes: number of bytes to complete @rq->next_rq | |
1892 | * @drv_callback: function called between completion of bios in the request | |
1893 | * and completion of the request. | |
1894 | * If the callback returns non %0, this helper returns without | |
1895 | * completion of the request. | |
1896 | * | |
1897 | * Description: | |
1898 | * Ends I/O on a number of bytes attached to @rq and @rq->next_rq. | |
1899 | * If @rq has leftover, sets it up for the next range of segments. | |
1900 | * | |
1901 | * Return: | |
1902 | * %0 - we are done with this request | |
1903 | * %1 - this request is not freed yet, it still has pending buffers. | |
1904 | **/ | |
1905 | static int blk_end_io(struct request *rq, int error, unsigned int nr_bytes, | |
1906 | unsigned int bidi_bytes, | |
1907 | int (drv_callback)(struct request *)) | |
1908 | { | |
1909 | struct request_queue *q = rq->q; | |
1910 | unsigned long flags = 0UL; | |
1911 | ||
1912 | if (bio_has_data(rq->bio) || blk_discard_rq(rq)) { | |
1913 | if (__end_that_request_first(rq, error, nr_bytes)) | |
1914 | return 1; | |
1915 | ||
1916 | /* Bidi request must be completed as a whole */ | |
1917 | if (blk_bidi_rq(rq) && | |
1918 | __end_that_request_first(rq->next_rq, error, bidi_bytes)) | |
1919 | return 1; | |
1920 | } | |
1921 | ||
1922 | /* Special feature for tricky drivers */ | |
1923 | if (drv_callback && drv_callback(rq)) | |
1924 | return 1; | |
1925 | ||
1926 | add_disk_randomness(rq->rq_disk); | |
1927 | ||
1928 | spin_lock_irqsave(q->queue_lock, flags); | |
1929 | end_that_request_last(rq, error); | |
1930 | spin_unlock_irqrestore(q->queue_lock, flags); | |
1931 | ||
1932 | return 0; | |
1933 | } | |
1934 | ||
1935 | /** | |
1936 | * blk_end_request - Helper function for drivers to complete the request. | |
1937 | * @rq: the request being processed | |
1938 | * @error: %0 for success, < %0 for error | |
1939 | * @nr_bytes: number of bytes to complete | |
1940 | * | |
1941 | * Description: | |
1942 | * Ends I/O on a number of bytes attached to @rq. | |
1943 | * If @rq has leftover, sets it up for the next range of segments. | |
1944 | * | |
1945 | * Return: | |
1946 | * %0 - we are done with this request | |
1947 | * %1 - still buffers pending for this request | |
1948 | **/ | |
1949 | int blk_end_request(struct request *rq, int error, unsigned int nr_bytes) | |
1950 | { | |
1951 | return blk_end_io(rq, error, nr_bytes, 0, NULL); | |
1952 | } | |
1953 | EXPORT_SYMBOL_GPL(blk_end_request); | |
1954 | ||
1955 | /** | |
1956 | * __blk_end_request - Helper function for drivers to complete the request. | |
1957 | * @rq: the request being processed | |
1958 | * @error: %0 for success, < %0 for error | |
1959 | * @nr_bytes: number of bytes to complete | |
1960 | * | |
1961 | * Description: | |
1962 | * Must be called with queue lock held unlike blk_end_request(). | |
1963 | * | |
1964 | * Return: | |
1965 | * %0 - we are done with this request | |
1966 | * %1 - still buffers pending for this request | |
1967 | **/ | |
1968 | int __blk_end_request(struct request *rq, int error, unsigned int nr_bytes) | |
1969 | { | |
1970 | if ((bio_has_data(rq->bio) || blk_discard_rq(rq)) && | |
1971 | __end_that_request_first(rq, error, nr_bytes)) | |
1972 | return 1; | |
1973 | ||
1974 | add_disk_randomness(rq->rq_disk); | |
1975 | ||
1976 | end_that_request_last(rq, error); | |
1977 | ||
1978 | return 0; | |
1979 | } | |
1980 | EXPORT_SYMBOL_GPL(__blk_end_request); | |
1981 | ||
1982 | /** | |
1983 | * blk_end_bidi_request - Helper function for drivers to complete bidi request. | |
1984 | * @rq: the bidi request being processed | |
1985 | * @error: %0 for success, < %0 for error | |
1986 | * @nr_bytes: number of bytes to complete @rq | |
1987 | * @bidi_bytes: number of bytes to complete @rq->next_rq | |
1988 | * | |
1989 | * Description: | |
1990 | * Ends I/O on a number of bytes attached to @rq and @rq->next_rq. | |
1991 | * | |
1992 | * Return: | |
1993 | * %0 - we are done with this request | |
1994 | * %1 - still buffers pending for this request | |
1995 | **/ | |
1996 | int blk_end_bidi_request(struct request *rq, int error, unsigned int nr_bytes, | |
1997 | unsigned int bidi_bytes) | |
1998 | { | |
1999 | return blk_end_io(rq, error, nr_bytes, bidi_bytes, NULL); | |
2000 | } | |
2001 | EXPORT_SYMBOL_GPL(blk_end_bidi_request); | |
2002 | ||
2003 | /** | |
2004 | * blk_end_request_callback - Special helper function for tricky drivers | |
2005 | * @rq: the request being processed | |
2006 | * @error: %0 for success, < %0 for error | |
2007 | * @nr_bytes: number of bytes to complete | |
2008 | * @drv_callback: function called between completion of bios in the request | |
2009 | * and completion of the request. | |
2010 | * If the callback returns non %0, this helper returns without | |
2011 | * completion of the request. | |
2012 | * | |
2013 | * Description: | |
2014 | * Ends I/O on a number of bytes attached to @rq. | |
2015 | * If @rq has leftover, sets it up for the next range of segments. | |
2016 | * | |
2017 | * This special helper function is used only for existing tricky drivers. | |
2018 | * (e.g. cdrom_newpc_intr() of ide-cd) | |
2019 | * This interface will be removed when such drivers are rewritten. | |
2020 | * Don't use this interface in other places anymore. | |
2021 | * | |
2022 | * Return: | |
2023 | * %0 - we are done with this request | |
2024 | * %1 - this request is not freed yet. | |
2025 | * this request still has pending buffers or | |
2026 | * the driver doesn't want to finish this request yet. | |
2027 | **/ | |
2028 | int blk_end_request_callback(struct request *rq, int error, | |
2029 | unsigned int nr_bytes, | |
2030 | int (drv_callback)(struct request *)) | |
2031 | { | |
2032 | return blk_end_io(rq, error, nr_bytes, 0, drv_callback); | |
2033 | } | |
2034 | EXPORT_SYMBOL_GPL(blk_end_request_callback); | |
2035 | ||
2036 | void blk_rq_bio_prep(struct request_queue *q, struct request *rq, | |
2037 | struct bio *bio) | |
2038 | { | |
2039 | /* Bit 0 (R/W) is identical in rq->cmd_flags and bio->bi_rw, and | |
2040 | we want BIO_RW_AHEAD (bit 1) to imply REQ_FAILFAST (bit 1). */ | |
2041 | rq->cmd_flags |= (bio->bi_rw & 3); | |
2042 | ||
2043 | if (bio_has_data(bio)) { | |
2044 | rq->nr_phys_segments = bio_phys_segments(q, bio); | |
2045 | rq->buffer = bio_data(bio); | |
2046 | } | |
2047 | rq->current_nr_sectors = bio_cur_sectors(bio); | |
2048 | rq->hard_cur_sectors = rq->current_nr_sectors; | |
2049 | rq->hard_nr_sectors = rq->nr_sectors = bio_sectors(bio); | |
2050 | rq->data_len = bio->bi_size; | |
2051 | ||
2052 | rq->bio = rq->biotail = bio; | |
2053 | ||
2054 | if (bio->bi_bdev) | |
2055 | rq->rq_disk = bio->bi_bdev->bd_disk; | |
2056 | } | |
2057 | ||
2058 | int kblockd_schedule_work(struct work_struct *work) | |
2059 | { | |
2060 | return queue_work(kblockd_workqueue, work); | |
2061 | } | |
2062 | EXPORT_SYMBOL(kblockd_schedule_work); | |
2063 | ||
2064 | void kblockd_flush_work(struct work_struct *work) | |
2065 | { | |
2066 | cancel_work_sync(work); | |
2067 | } | |
2068 | EXPORT_SYMBOL(kblockd_flush_work); | |
2069 | ||
2070 | int __init blk_dev_init(void) | |
2071 | { | |
2072 | int i; | |
2073 | ||
2074 | kblockd_workqueue = create_workqueue("kblockd"); | |
2075 | if (!kblockd_workqueue) | |
2076 | panic("Failed to create kblockd\n"); | |
2077 | ||
2078 | request_cachep = kmem_cache_create("blkdev_requests", | |
2079 | sizeof(struct request), 0, SLAB_PANIC, NULL); | |
2080 | ||
2081 | blk_requestq_cachep = kmem_cache_create("blkdev_queue", | |
2082 | sizeof(struct request_queue), 0, SLAB_PANIC, NULL); | |
2083 | ||
2084 | for_each_possible_cpu(i) | |
2085 | INIT_LIST_HEAD(&per_cpu(blk_cpu_done, i)); | |
2086 | ||
2087 | open_softirq(BLOCK_SOFTIRQ, blk_done_softirq); | |
2088 | register_hotcpu_notifier(&blk_cpu_notifier); | |
2089 | ||
2090 | return 0; | |
2091 | } | |
2092 |