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1da177e4 LT |
1 | /* |
2 | * linux/drivers/block/ll_rw_blk.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | * Copyright (C) 1994, Karl Keyte: Added support for disk statistics | |
6 | * Elevator latency, (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE | |
7 | * Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de> | |
8 | * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au> - July2000 | |
9 | * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001 | |
10 | */ | |
11 | ||
12 | /* | |
13 | * This handles all read/write requests to block devices | |
14 | */ | |
15 | #include <linux/config.h> | |
16 | #include <linux/kernel.h> | |
17 | #include <linux/module.h> | |
18 | #include <linux/backing-dev.h> | |
19 | #include <linux/bio.h> | |
20 | #include <linux/blkdev.h> | |
21 | #include <linux/highmem.h> | |
22 | #include <linux/mm.h> | |
23 | #include <linux/kernel_stat.h> | |
24 | #include <linux/string.h> | |
25 | #include <linux/init.h> | |
26 | #include <linux/bootmem.h> /* for max_pfn/max_low_pfn */ | |
27 | #include <linux/completion.h> | |
28 | #include <linux/slab.h> | |
29 | #include <linux/swap.h> | |
30 | #include <linux/writeback.h> | |
1946089a | 31 | #include <linux/blkdev.h> |
1da177e4 LT |
32 | |
33 | /* | |
34 | * for max sense size | |
35 | */ | |
36 | #include <scsi/scsi_cmnd.h> | |
37 | ||
38 | static void blk_unplug_work(void *data); | |
39 | static void blk_unplug_timeout(unsigned long data); | |
40 | ||
41 | /* | |
42 | * For the allocated request tables | |
43 | */ | |
44 | static kmem_cache_t *request_cachep; | |
45 | ||
46 | /* | |
47 | * For queue allocation | |
48 | */ | |
49 | static kmem_cache_t *requestq_cachep; | |
50 | ||
51 | /* | |
52 | * For io context allocations | |
53 | */ | |
54 | static kmem_cache_t *iocontext_cachep; | |
55 | ||
56 | static wait_queue_head_t congestion_wqh[2] = { | |
57 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]), | |
58 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1]) | |
59 | }; | |
60 | ||
61 | /* | |
62 | * Controlling structure to kblockd | |
63 | */ | |
64 | static struct workqueue_struct *kblockd_workqueue; | |
65 | ||
66 | unsigned long blk_max_low_pfn, blk_max_pfn; | |
67 | ||
68 | EXPORT_SYMBOL(blk_max_low_pfn); | |
69 | EXPORT_SYMBOL(blk_max_pfn); | |
70 | ||
71 | /* Amount of time in which a process may batch requests */ | |
72 | #define BLK_BATCH_TIME (HZ/50UL) | |
73 | ||
74 | /* Number of requests a "batching" process may submit */ | |
75 | #define BLK_BATCH_REQ 32 | |
76 | ||
77 | /* | |
78 | * Return the threshold (number of used requests) at which the queue is | |
79 | * considered to be congested. It include a little hysteresis to keep the | |
80 | * context switch rate down. | |
81 | */ | |
82 | static inline int queue_congestion_on_threshold(struct request_queue *q) | |
83 | { | |
84 | return q->nr_congestion_on; | |
85 | } | |
86 | ||
87 | /* | |
88 | * The threshold at which a queue is considered to be uncongested | |
89 | */ | |
90 | static inline int queue_congestion_off_threshold(struct request_queue *q) | |
91 | { | |
92 | return q->nr_congestion_off; | |
93 | } | |
94 | ||
95 | static void blk_queue_congestion_threshold(struct request_queue *q) | |
96 | { | |
97 | int nr; | |
98 | ||
99 | nr = q->nr_requests - (q->nr_requests / 8) + 1; | |
100 | if (nr > q->nr_requests) | |
101 | nr = q->nr_requests; | |
102 | q->nr_congestion_on = nr; | |
103 | ||
104 | nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1; | |
105 | if (nr < 1) | |
106 | nr = 1; | |
107 | q->nr_congestion_off = nr; | |
108 | } | |
109 | ||
110 | /* | |
111 | * A queue has just exitted congestion. Note this in the global counter of | |
112 | * congested queues, and wake up anyone who was waiting for requests to be | |
113 | * put back. | |
114 | */ | |
115 | static void clear_queue_congested(request_queue_t *q, int rw) | |
116 | { | |
117 | enum bdi_state bit; | |
118 | wait_queue_head_t *wqh = &congestion_wqh[rw]; | |
119 | ||
120 | bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested; | |
121 | clear_bit(bit, &q->backing_dev_info.state); | |
122 | smp_mb__after_clear_bit(); | |
123 | if (waitqueue_active(wqh)) | |
124 | wake_up(wqh); | |
125 | } | |
126 | ||
127 | /* | |
128 | * A queue has just entered congestion. Flag that in the queue's VM-visible | |
129 | * state flags and increment the global gounter of congested queues. | |
130 | */ | |
131 | static void set_queue_congested(request_queue_t *q, int rw) | |
132 | { | |
133 | enum bdi_state bit; | |
134 | ||
135 | bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested; | |
136 | set_bit(bit, &q->backing_dev_info.state); | |
137 | } | |
138 | ||
139 | /** | |
140 | * blk_get_backing_dev_info - get the address of a queue's backing_dev_info | |
141 | * @bdev: device | |
142 | * | |
143 | * Locates the passed device's request queue and returns the address of its | |
144 | * backing_dev_info | |
145 | * | |
146 | * Will return NULL if the request queue cannot be located. | |
147 | */ | |
148 | struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev) | |
149 | { | |
150 | struct backing_dev_info *ret = NULL; | |
151 | request_queue_t *q = bdev_get_queue(bdev); | |
152 | ||
153 | if (q) | |
154 | ret = &q->backing_dev_info; | |
155 | return ret; | |
156 | } | |
157 | ||
158 | EXPORT_SYMBOL(blk_get_backing_dev_info); | |
159 | ||
160 | void blk_queue_activity_fn(request_queue_t *q, activity_fn *fn, void *data) | |
161 | { | |
162 | q->activity_fn = fn; | |
163 | q->activity_data = data; | |
164 | } | |
165 | ||
166 | EXPORT_SYMBOL(blk_queue_activity_fn); | |
167 | ||
168 | /** | |
169 | * blk_queue_prep_rq - set a prepare_request function for queue | |
170 | * @q: queue | |
171 | * @pfn: prepare_request function | |
172 | * | |
173 | * It's possible for a queue to register a prepare_request callback which | |
174 | * is invoked before the request is handed to the request_fn. The goal of | |
175 | * the function is to prepare a request for I/O, it can be used to build a | |
176 | * cdb from the request data for instance. | |
177 | * | |
178 | */ | |
179 | void blk_queue_prep_rq(request_queue_t *q, prep_rq_fn *pfn) | |
180 | { | |
181 | q->prep_rq_fn = pfn; | |
182 | } | |
183 | ||
184 | EXPORT_SYMBOL(blk_queue_prep_rq); | |
185 | ||
186 | /** | |
187 | * blk_queue_merge_bvec - set a merge_bvec function for queue | |
188 | * @q: queue | |
189 | * @mbfn: merge_bvec_fn | |
190 | * | |
191 | * Usually queues have static limitations on the max sectors or segments that | |
192 | * we can put in a request. Stacking drivers may have some settings that | |
193 | * are dynamic, and thus we have to query the queue whether it is ok to | |
194 | * add a new bio_vec to a bio at a given offset or not. If the block device | |
195 | * has such limitations, it needs to register a merge_bvec_fn to control | |
196 | * the size of bio's sent to it. Note that a block device *must* allow a | |
197 | * single page to be added to an empty bio. The block device driver may want | |
198 | * to use the bio_split() function to deal with these bio's. By default | |
199 | * no merge_bvec_fn is defined for a queue, and only the fixed limits are | |
200 | * honored. | |
201 | */ | |
202 | void blk_queue_merge_bvec(request_queue_t *q, merge_bvec_fn *mbfn) | |
203 | { | |
204 | q->merge_bvec_fn = mbfn; | |
205 | } | |
206 | ||
207 | EXPORT_SYMBOL(blk_queue_merge_bvec); | |
208 | ||
209 | /** | |
210 | * blk_queue_make_request - define an alternate make_request function for a device | |
211 | * @q: the request queue for the device to be affected | |
212 | * @mfn: the alternate make_request function | |
213 | * | |
214 | * Description: | |
215 | * The normal way for &struct bios to be passed to a device | |
216 | * driver is for them to be collected into requests on a request | |
217 | * queue, and then to allow the device driver to select requests | |
218 | * off that queue when it is ready. This works well for many block | |
219 | * devices. However some block devices (typically virtual devices | |
220 | * such as md or lvm) do not benefit from the processing on the | |
221 | * request queue, and are served best by having the requests passed | |
222 | * directly to them. This can be achieved by providing a function | |
223 | * to blk_queue_make_request(). | |
224 | * | |
225 | * Caveat: | |
226 | * The driver that does this *must* be able to deal appropriately | |
227 | * with buffers in "highmemory". This can be accomplished by either calling | |
228 | * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling | |
229 | * blk_queue_bounce() to create a buffer in normal memory. | |
230 | **/ | |
231 | void blk_queue_make_request(request_queue_t * q, make_request_fn * mfn) | |
232 | { | |
233 | /* | |
234 | * set defaults | |
235 | */ | |
236 | q->nr_requests = BLKDEV_MAX_RQ; | |
237 | q->max_phys_segments = MAX_PHYS_SEGMENTS; | |
238 | q->max_hw_segments = MAX_HW_SEGMENTS; | |
239 | q->make_request_fn = mfn; | |
240 | q->backing_dev_info.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE; | |
241 | q->backing_dev_info.state = 0; | |
242 | q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY; | |
243 | blk_queue_max_sectors(q, MAX_SECTORS); | |
244 | blk_queue_hardsect_size(q, 512); | |
245 | blk_queue_dma_alignment(q, 511); | |
246 | blk_queue_congestion_threshold(q); | |
247 | q->nr_batching = BLK_BATCH_REQ; | |
248 | ||
249 | q->unplug_thresh = 4; /* hmm */ | |
250 | q->unplug_delay = (3 * HZ) / 1000; /* 3 milliseconds */ | |
251 | if (q->unplug_delay == 0) | |
252 | q->unplug_delay = 1; | |
253 | ||
254 | INIT_WORK(&q->unplug_work, blk_unplug_work, q); | |
255 | ||
256 | q->unplug_timer.function = blk_unplug_timeout; | |
257 | q->unplug_timer.data = (unsigned long)q; | |
258 | ||
259 | /* | |
260 | * by default assume old behaviour and bounce for any highmem page | |
261 | */ | |
262 | blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH); | |
263 | ||
264 | blk_queue_activity_fn(q, NULL, NULL); | |
265 | ||
266 | INIT_LIST_HEAD(&q->drain_list); | |
267 | } | |
268 | ||
269 | EXPORT_SYMBOL(blk_queue_make_request); | |
270 | ||
271 | static inline void rq_init(request_queue_t *q, struct request *rq) | |
272 | { | |
273 | INIT_LIST_HEAD(&rq->queuelist); | |
274 | ||
275 | rq->errors = 0; | |
276 | rq->rq_status = RQ_ACTIVE; | |
277 | rq->bio = rq->biotail = NULL; | |
278 | rq->buffer = NULL; | |
279 | rq->ref_count = 1; | |
280 | rq->q = q; | |
281 | rq->waiting = NULL; | |
282 | rq->special = NULL; | |
283 | rq->data_len = 0; | |
284 | rq->data = NULL; | |
285 | rq->sense = NULL; | |
286 | rq->end_io = NULL; | |
287 | rq->end_io_data = NULL; | |
288 | } | |
289 | ||
290 | /** | |
291 | * blk_queue_ordered - does this queue support ordered writes | |
292 | * @q: the request queue | |
293 | * @flag: see below | |
294 | * | |
295 | * Description: | |
296 | * For journalled file systems, doing ordered writes on a commit | |
297 | * block instead of explicitly doing wait_on_buffer (which is bad | |
298 | * for performance) can be a big win. Block drivers supporting this | |
299 | * feature should call this function and indicate so. | |
300 | * | |
301 | **/ | |
302 | void blk_queue_ordered(request_queue_t *q, int flag) | |
303 | { | |
304 | switch (flag) { | |
305 | case QUEUE_ORDERED_NONE: | |
306 | if (q->flush_rq) | |
307 | kmem_cache_free(request_cachep, q->flush_rq); | |
308 | q->flush_rq = NULL; | |
309 | q->ordered = flag; | |
310 | break; | |
311 | case QUEUE_ORDERED_TAG: | |
312 | q->ordered = flag; | |
313 | break; | |
314 | case QUEUE_ORDERED_FLUSH: | |
315 | q->ordered = flag; | |
316 | if (!q->flush_rq) | |
317 | q->flush_rq = kmem_cache_alloc(request_cachep, | |
318 | GFP_KERNEL); | |
319 | break; | |
320 | default: | |
321 | printk("blk_queue_ordered: bad value %d\n", flag); | |
322 | break; | |
323 | } | |
324 | } | |
325 | ||
326 | EXPORT_SYMBOL(blk_queue_ordered); | |
327 | ||
328 | /** | |
329 | * blk_queue_issue_flush_fn - set function for issuing a flush | |
330 | * @q: the request queue | |
331 | * @iff: the function to be called issuing the flush | |
332 | * | |
333 | * Description: | |
334 | * If a driver supports issuing a flush command, the support is notified | |
335 | * to the block layer by defining it through this call. | |
336 | * | |
337 | **/ | |
338 | void blk_queue_issue_flush_fn(request_queue_t *q, issue_flush_fn *iff) | |
339 | { | |
340 | q->issue_flush_fn = iff; | |
341 | } | |
342 | ||
343 | EXPORT_SYMBOL(blk_queue_issue_flush_fn); | |
344 | ||
345 | /* | |
346 | * Cache flushing for ordered writes handling | |
347 | */ | |
348 | static void blk_pre_flush_end_io(struct request *flush_rq) | |
349 | { | |
350 | struct request *rq = flush_rq->end_io_data; | |
351 | request_queue_t *q = rq->q; | |
352 | ||
353 | rq->flags |= REQ_BAR_PREFLUSH; | |
354 | ||
355 | if (!flush_rq->errors) | |
356 | elv_requeue_request(q, rq); | |
357 | else { | |
358 | q->end_flush_fn(q, flush_rq); | |
359 | clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags); | |
360 | q->request_fn(q); | |
361 | } | |
362 | } | |
363 | ||
364 | static void blk_post_flush_end_io(struct request *flush_rq) | |
365 | { | |
366 | struct request *rq = flush_rq->end_io_data; | |
367 | request_queue_t *q = rq->q; | |
368 | ||
369 | rq->flags |= REQ_BAR_POSTFLUSH; | |
370 | ||
371 | q->end_flush_fn(q, flush_rq); | |
372 | clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags); | |
373 | q->request_fn(q); | |
374 | } | |
375 | ||
376 | struct request *blk_start_pre_flush(request_queue_t *q, struct request *rq) | |
377 | { | |
378 | struct request *flush_rq = q->flush_rq; | |
379 | ||
380 | BUG_ON(!blk_barrier_rq(rq)); | |
381 | ||
382 | if (test_and_set_bit(QUEUE_FLAG_FLUSH, &q->queue_flags)) | |
383 | return NULL; | |
384 | ||
385 | rq_init(q, flush_rq); | |
386 | flush_rq->elevator_private = NULL; | |
387 | flush_rq->flags = REQ_BAR_FLUSH; | |
388 | flush_rq->rq_disk = rq->rq_disk; | |
389 | flush_rq->rl = NULL; | |
390 | ||
391 | /* | |
392 | * prepare_flush returns 0 if no flush is needed, just mark both | |
393 | * pre and post flush as done in that case | |
394 | */ | |
395 | if (!q->prepare_flush_fn(q, flush_rq)) { | |
396 | rq->flags |= REQ_BAR_PREFLUSH | REQ_BAR_POSTFLUSH; | |
397 | clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags); | |
398 | return rq; | |
399 | } | |
400 | ||
401 | /* | |
402 | * some drivers dequeue requests right away, some only after io | |
403 | * completion. make sure the request is dequeued. | |
404 | */ | |
405 | if (!list_empty(&rq->queuelist)) | |
406 | blkdev_dequeue_request(rq); | |
407 | ||
408 | elv_deactivate_request(q, rq); | |
409 | ||
410 | flush_rq->end_io_data = rq; | |
411 | flush_rq->end_io = blk_pre_flush_end_io; | |
412 | ||
413 | __elv_add_request(q, flush_rq, ELEVATOR_INSERT_FRONT, 0); | |
414 | return flush_rq; | |
415 | } | |
416 | ||
417 | static void blk_start_post_flush(request_queue_t *q, struct request *rq) | |
418 | { | |
419 | struct request *flush_rq = q->flush_rq; | |
420 | ||
421 | BUG_ON(!blk_barrier_rq(rq)); | |
422 | ||
423 | rq_init(q, flush_rq); | |
424 | flush_rq->elevator_private = NULL; | |
425 | flush_rq->flags = REQ_BAR_FLUSH; | |
426 | flush_rq->rq_disk = rq->rq_disk; | |
427 | flush_rq->rl = NULL; | |
428 | ||
429 | if (q->prepare_flush_fn(q, flush_rq)) { | |
430 | flush_rq->end_io_data = rq; | |
431 | flush_rq->end_io = blk_post_flush_end_io; | |
432 | ||
433 | __elv_add_request(q, flush_rq, ELEVATOR_INSERT_FRONT, 0); | |
434 | q->request_fn(q); | |
435 | } | |
436 | } | |
437 | ||
438 | static inline int blk_check_end_barrier(request_queue_t *q, struct request *rq, | |
439 | int sectors) | |
440 | { | |
441 | if (sectors > rq->nr_sectors) | |
442 | sectors = rq->nr_sectors; | |
443 | ||
444 | rq->nr_sectors -= sectors; | |
445 | return rq->nr_sectors; | |
446 | } | |
447 | ||
448 | static int __blk_complete_barrier_rq(request_queue_t *q, struct request *rq, | |
449 | int sectors, int queue_locked) | |
450 | { | |
451 | if (q->ordered != QUEUE_ORDERED_FLUSH) | |
452 | return 0; | |
453 | if (!blk_fs_request(rq) || !blk_barrier_rq(rq)) | |
454 | return 0; | |
455 | if (blk_barrier_postflush(rq)) | |
456 | return 0; | |
457 | ||
458 | if (!blk_check_end_barrier(q, rq, sectors)) { | |
459 | unsigned long flags = 0; | |
460 | ||
461 | if (!queue_locked) | |
462 | spin_lock_irqsave(q->queue_lock, flags); | |
463 | ||
464 | blk_start_post_flush(q, rq); | |
465 | ||
466 | if (!queue_locked) | |
467 | spin_unlock_irqrestore(q->queue_lock, flags); | |
468 | } | |
469 | ||
470 | return 1; | |
471 | } | |
472 | ||
473 | /** | |
474 | * blk_complete_barrier_rq - complete possible barrier request | |
475 | * @q: the request queue for the device | |
476 | * @rq: the request | |
477 | * @sectors: number of sectors to complete | |
478 | * | |
479 | * Description: | |
480 | * Used in driver end_io handling to determine whether to postpone | |
481 | * completion of a barrier request until a post flush has been done. This | |
482 | * is the unlocked variant, used if the caller doesn't already hold the | |
483 | * queue lock. | |
484 | **/ | |
485 | int blk_complete_barrier_rq(request_queue_t *q, struct request *rq, int sectors) | |
486 | { | |
487 | return __blk_complete_barrier_rq(q, rq, sectors, 0); | |
488 | } | |
489 | EXPORT_SYMBOL(blk_complete_barrier_rq); | |
490 | ||
491 | /** | |
492 | * blk_complete_barrier_rq_locked - complete possible barrier request | |
493 | * @q: the request queue for the device | |
494 | * @rq: the request | |
495 | * @sectors: number of sectors to complete | |
496 | * | |
497 | * Description: | |
498 | * See blk_complete_barrier_rq(). This variant must be used if the caller | |
499 | * holds the queue lock. | |
500 | **/ | |
501 | int blk_complete_barrier_rq_locked(request_queue_t *q, struct request *rq, | |
502 | int sectors) | |
503 | { | |
504 | return __blk_complete_barrier_rq(q, rq, sectors, 1); | |
505 | } | |
506 | EXPORT_SYMBOL(blk_complete_barrier_rq_locked); | |
507 | ||
508 | /** | |
509 | * blk_queue_bounce_limit - set bounce buffer limit for queue | |
510 | * @q: the request queue for the device | |
511 | * @dma_addr: bus address limit | |
512 | * | |
513 | * Description: | |
514 | * Different hardware can have different requirements as to what pages | |
515 | * it can do I/O directly to. A low level driver can call | |
516 | * blk_queue_bounce_limit to have lower memory pages allocated as bounce | |
517 | * buffers for doing I/O to pages residing above @page. By default | |
518 | * the block layer sets this to the highest numbered "low" memory page. | |
519 | **/ | |
520 | void blk_queue_bounce_limit(request_queue_t *q, u64 dma_addr) | |
521 | { | |
522 | unsigned long bounce_pfn = dma_addr >> PAGE_SHIFT; | |
523 | ||
524 | /* | |
525 | * set appropriate bounce gfp mask -- unfortunately we don't have a | |
526 | * full 4GB zone, so we have to resort to low memory for any bounces. | |
527 | * ISA has its own < 16MB zone. | |
528 | */ | |
529 | if (bounce_pfn < blk_max_low_pfn) { | |
530 | BUG_ON(dma_addr < BLK_BOUNCE_ISA); | |
531 | init_emergency_isa_pool(); | |
532 | q->bounce_gfp = GFP_NOIO | GFP_DMA; | |
533 | } else | |
534 | q->bounce_gfp = GFP_NOIO; | |
535 | ||
536 | q->bounce_pfn = bounce_pfn; | |
537 | } | |
538 | ||
539 | EXPORT_SYMBOL(blk_queue_bounce_limit); | |
540 | ||
541 | /** | |
542 | * blk_queue_max_sectors - set max sectors for a request for this queue | |
543 | * @q: the request queue for the device | |
544 | * @max_sectors: max sectors in the usual 512b unit | |
545 | * | |
546 | * Description: | |
547 | * Enables a low level driver to set an upper limit on the size of | |
548 | * received requests. | |
549 | **/ | |
550 | void blk_queue_max_sectors(request_queue_t *q, unsigned short max_sectors) | |
551 | { | |
552 | if ((max_sectors << 9) < PAGE_CACHE_SIZE) { | |
553 | max_sectors = 1 << (PAGE_CACHE_SHIFT - 9); | |
554 | printk("%s: set to minimum %d\n", __FUNCTION__, max_sectors); | |
555 | } | |
556 | ||
557 | q->max_sectors = q->max_hw_sectors = max_sectors; | |
558 | } | |
559 | ||
560 | EXPORT_SYMBOL(blk_queue_max_sectors); | |
561 | ||
562 | /** | |
563 | * blk_queue_max_phys_segments - set max phys segments for a request for this queue | |
564 | * @q: the request queue for the device | |
565 | * @max_segments: max number of segments | |
566 | * | |
567 | * Description: | |
568 | * Enables a low level driver to set an upper limit on the number of | |
569 | * physical data segments in a request. This would be the largest sized | |
570 | * scatter list the driver could handle. | |
571 | **/ | |
572 | void blk_queue_max_phys_segments(request_queue_t *q, unsigned short max_segments) | |
573 | { | |
574 | if (!max_segments) { | |
575 | max_segments = 1; | |
576 | printk("%s: set to minimum %d\n", __FUNCTION__, max_segments); | |
577 | } | |
578 | ||
579 | q->max_phys_segments = max_segments; | |
580 | } | |
581 | ||
582 | EXPORT_SYMBOL(blk_queue_max_phys_segments); | |
583 | ||
584 | /** | |
585 | * blk_queue_max_hw_segments - set max hw segments for a request for this queue | |
586 | * @q: the request queue for the device | |
587 | * @max_segments: max number of segments | |
588 | * | |
589 | * Description: | |
590 | * Enables a low level driver to set an upper limit on the number of | |
591 | * hw data segments in a request. This would be the largest number of | |
592 | * address/length pairs the host adapter can actually give as once | |
593 | * to the device. | |
594 | **/ | |
595 | void blk_queue_max_hw_segments(request_queue_t *q, unsigned short max_segments) | |
596 | { | |
597 | if (!max_segments) { | |
598 | max_segments = 1; | |
599 | printk("%s: set to minimum %d\n", __FUNCTION__, max_segments); | |
600 | } | |
601 | ||
602 | q->max_hw_segments = max_segments; | |
603 | } | |
604 | ||
605 | EXPORT_SYMBOL(blk_queue_max_hw_segments); | |
606 | ||
607 | /** | |
608 | * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg | |
609 | * @q: the request queue for the device | |
610 | * @max_size: max size of segment in bytes | |
611 | * | |
612 | * Description: | |
613 | * Enables a low level driver to set an upper limit on the size of a | |
614 | * coalesced segment | |
615 | **/ | |
616 | void blk_queue_max_segment_size(request_queue_t *q, unsigned int max_size) | |
617 | { | |
618 | if (max_size < PAGE_CACHE_SIZE) { | |
619 | max_size = PAGE_CACHE_SIZE; | |
620 | printk("%s: set to minimum %d\n", __FUNCTION__, max_size); | |
621 | } | |
622 | ||
623 | q->max_segment_size = max_size; | |
624 | } | |
625 | ||
626 | EXPORT_SYMBOL(blk_queue_max_segment_size); | |
627 | ||
628 | /** | |
629 | * blk_queue_hardsect_size - set hardware sector size for the queue | |
630 | * @q: the request queue for the device | |
631 | * @size: the hardware sector size, in bytes | |
632 | * | |
633 | * Description: | |
634 | * This should typically be set to the lowest possible sector size | |
635 | * that the hardware can operate on (possible without reverting to | |
636 | * even internal read-modify-write operations). Usually the default | |
637 | * of 512 covers most hardware. | |
638 | **/ | |
639 | void blk_queue_hardsect_size(request_queue_t *q, unsigned short size) | |
640 | { | |
641 | q->hardsect_size = size; | |
642 | } | |
643 | ||
644 | EXPORT_SYMBOL(blk_queue_hardsect_size); | |
645 | ||
646 | /* | |
647 | * Returns the minimum that is _not_ zero, unless both are zero. | |
648 | */ | |
649 | #define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r)) | |
650 | ||
651 | /** | |
652 | * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers | |
653 | * @t: the stacking driver (top) | |
654 | * @b: the underlying device (bottom) | |
655 | **/ | |
656 | void blk_queue_stack_limits(request_queue_t *t, request_queue_t *b) | |
657 | { | |
658 | /* zero is "infinity" */ | |
659 | t->max_sectors = t->max_hw_sectors = | |
660 | min_not_zero(t->max_sectors,b->max_sectors); | |
661 | ||
662 | t->max_phys_segments = min(t->max_phys_segments,b->max_phys_segments); | |
663 | t->max_hw_segments = min(t->max_hw_segments,b->max_hw_segments); | |
664 | t->max_segment_size = min(t->max_segment_size,b->max_segment_size); | |
665 | t->hardsect_size = max(t->hardsect_size,b->hardsect_size); | |
666 | } | |
667 | ||
668 | EXPORT_SYMBOL(blk_queue_stack_limits); | |
669 | ||
670 | /** | |
671 | * blk_queue_segment_boundary - set boundary rules for segment merging | |
672 | * @q: the request queue for the device | |
673 | * @mask: the memory boundary mask | |
674 | **/ | |
675 | void blk_queue_segment_boundary(request_queue_t *q, unsigned long mask) | |
676 | { | |
677 | if (mask < PAGE_CACHE_SIZE - 1) { | |
678 | mask = PAGE_CACHE_SIZE - 1; | |
679 | printk("%s: set to minimum %lx\n", __FUNCTION__, mask); | |
680 | } | |
681 | ||
682 | q->seg_boundary_mask = mask; | |
683 | } | |
684 | ||
685 | EXPORT_SYMBOL(blk_queue_segment_boundary); | |
686 | ||
687 | /** | |
688 | * blk_queue_dma_alignment - set dma length and memory alignment | |
689 | * @q: the request queue for the device | |
690 | * @mask: alignment mask | |
691 | * | |
692 | * description: | |
693 | * set required memory and length aligment for direct dma transactions. | |
694 | * this is used when buiding direct io requests for the queue. | |
695 | * | |
696 | **/ | |
697 | void blk_queue_dma_alignment(request_queue_t *q, int mask) | |
698 | { | |
699 | q->dma_alignment = mask; | |
700 | } | |
701 | ||
702 | EXPORT_SYMBOL(blk_queue_dma_alignment); | |
703 | ||
704 | /** | |
705 | * blk_queue_find_tag - find a request by its tag and queue | |
706 | * | |
707 | * @q: The request queue for the device | |
708 | * @tag: The tag of the request | |
709 | * | |
710 | * Notes: | |
711 | * Should be used when a device returns a tag and you want to match | |
712 | * it with a request. | |
713 | * | |
714 | * no locks need be held. | |
715 | **/ | |
716 | struct request *blk_queue_find_tag(request_queue_t *q, int tag) | |
717 | { | |
718 | struct blk_queue_tag *bqt = q->queue_tags; | |
719 | ||
fa72b903 | 720 | if (unlikely(bqt == NULL || tag >= bqt->max_depth)) |
1da177e4 LT |
721 | return NULL; |
722 | ||
723 | return bqt->tag_index[tag]; | |
724 | } | |
725 | ||
726 | EXPORT_SYMBOL(blk_queue_find_tag); | |
727 | ||
728 | /** | |
729 | * __blk_queue_free_tags - release tag maintenance info | |
730 | * @q: the request queue for the device | |
731 | * | |
732 | * Notes: | |
733 | * blk_cleanup_queue() will take care of calling this function, if tagging | |
734 | * has been used. So there's no need to call this directly. | |
735 | **/ | |
736 | static void __blk_queue_free_tags(request_queue_t *q) | |
737 | { | |
738 | struct blk_queue_tag *bqt = q->queue_tags; | |
739 | ||
740 | if (!bqt) | |
741 | return; | |
742 | ||
743 | if (atomic_dec_and_test(&bqt->refcnt)) { | |
744 | BUG_ON(bqt->busy); | |
745 | BUG_ON(!list_empty(&bqt->busy_list)); | |
746 | ||
747 | kfree(bqt->tag_index); | |
748 | bqt->tag_index = NULL; | |
749 | ||
750 | kfree(bqt->tag_map); | |
751 | bqt->tag_map = NULL; | |
752 | ||
753 | kfree(bqt); | |
754 | } | |
755 | ||
756 | q->queue_tags = NULL; | |
757 | q->queue_flags &= ~(1 << QUEUE_FLAG_QUEUED); | |
758 | } | |
759 | ||
760 | /** | |
761 | * blk_queue_free_tags - release tag maintenance info | |
762 | * @q: the request queue for the device | |
763 | * | |
764 | * Notes: | |
765 | * This is used to disabled tagged queuing to a device, yet leave | |
766 | * queue in function. | |
767 | **/ | |
768 | void blk_queue_free_tags(request_queue_t *q) | |
769 | { | |
770 | clear_bit(QUEUE_FLAG_QUEUED, &q->queue_flags); | |
771 | } | |
772 | ||
773 | EXPORT_SYMBOL(blk_queue_free_tags); | |
774 | ||
775 | static int | |
776 | init_tag_map(request_queue_t *q, struct blk_queue_tag *tags, int depth) | |
777 | { | |
1da177e4 LT |
778 | struct request **tag_index; |
779 | unsigned long *tag_map; | |
fa72b903 | 780 | int nr_ulongs; |
1da177e4 LT |
781 | |
782 | if (depth > q->nr_requests * 2) { | |
783 | depth = q->nr_requests * 2; | |
784 | printk(KERN_ERR "%s: adjusted depth to %d\n", | |
785 | __FUNCTION__, depth); | |
786 | } | |
787 | ||
788 | tag_index = kmalloc(depth * sizeof(struct request *), GFP_ATOMIC); | |
789 | if (!tag_index) | |
790 | goto fail; | |
791 | ||
fa72b903 TH |
792 | nr_ulongs = ALIGN(depth, BLK_TAGS_PER_LONG) / BLK_TAGS_PER_LONG; |
793 | tag_map = kmalloc(nr_ulongs * sizeof(unsigned long), GFP_ATOMIC); | |
1da177e4 LT |
794 | if (!tag_map) |
795 | goto fail; | |
796 | ||
797 | memset(tag_index, 0, depth * sizeof(struct request *)); | |
fa72b903 | 798 | memset(tag_map, 0, nr_ulongs * sizeof(unsigned long)); |
1da177e4 | 799 | tags->max_depth = depth; |
1da177e4 LT |
800 | tags->tag_index = tag_index; |
801 | tags->tag_map = tag_map; | |
802 | ||
1da177e4 LT |
803 | return 0; |
804 | fail: | |
805 | kfree(tag_index); | |
806 | return -ENOMEM; | |
807 | } | |
808 | ||
809 | /** | |
810 | * blk_queue_init_tags - initialize the queue tag info | |
811 | * @q: the request queue for the device | |
812 | * @depth: the maximum queue depth supported | |
813 | * @tags: the tag to use | |
814 | **/ | |
815 | int blk_queue_init_tags(request_queue_t *q, int depth, | |
816 | struct blk_queue_tag *tags) | |
817 | { | |
818 | int rc; | |
819 | ||
820 | BUG_ON(tags && q->queue_tags && tags != q->queue_tags); | |
821 | ||
822 | if (!tags && !q->queue_tags) { | |
823 | tags = kmalloc(sizeof(struct blk_queue_tag), GFP_ATOMIC); | |
824 | if (!tags) | |
825 | goto fail; | |
826 | ||
827 | if (init_tag_map(q, tags, depth)) | |
828 | goto fail; | |
829 | ||
830 | INIT_LIST_HEAD(&tags->busy_list); | |
831 | tags->busy = 0; | |
832 | atomic_set(&tags->refcnt, 1); | |
833 | } else if (q->queue_tags) { | |
834 | if ((rc = blk_queue_resize_tags(q, depth))) | |
835 | return rc; | |
836 | set_bit(QUEUE_FLAG_QUEUED, &q->queue_flags); | |
837 | return 0; | |
838 | } else | |
839 | atomic_inc(&tags->refcnt); | |
840 | ||
841 | /* | |
842 | * assign it, all done | |
843 | */ | |
844 | q->queue_tags = tags; | |
845 | q->queue_flags |= (1 << QUEUE_FLAG_QUEUED); | |
846 | return 0; | |
847 | fail: | |
848 | kfree(tags); | |
849 | return -ENOMEM; | |
850 | } | |
851 | ||
852 | EXPORT_SYMBOL(blk_queue_init_tags); | |
853 | ||
854 | /** | |
855 | * blk_queue_resize_tags - change the queueing depth | |
856 | * @q: the request queue for the device | |
857 | * @new_depth: the new max command queueing depth | |
858 | * | |
859 | * Notes: | |
860 | * Must be called with the queue lock held. | |
861 | **/ | |
862 | int blk_queue_resize_tags(request_queue_t *q, int new_depth) | |
863 | { | |
864 | struct blk_queue_tag *bqt = q->queue_tags; | |
865 | struct request **tag_index; | |
866 | unsigned long *tag_map; | |
fa72b903 | 867 | int max_depth, nr_ulongs; |
1da177e4 LT |
868 | |
869 | if (!bqt) | |
870 | return -ENXIO; | |
871 | ||
1da177e4 LT |
872 | /* |
873 | * save the old state info, so we can copy it back | |
874 | */ | |
875 | tag_index = bqt->tag_index; | |
876 | tag_map = bqt->tag_map; | |
fa72b903 | 877 | max_depth = bqt->max_depth; |
1da177e4 LT |
878 | |
879 | if (init_tag_map(q, bqt, new_depth)) | |
880 | return -ENOMEM; | |
881 | ||
882 | memcpy(bqt->tag_index, tag_index, max_depth * sizeof(struct request *)); | |
fa72b903 TH |
883 | nr_ulongs = ALIGN(max_depth, BLK_TAGS_PER_LONG) / BLK_TAGS_PER_LONG; |
884 | memcpy(bqt->tag_map, tag_map, nr_ulongs * sizeof(unsigned long)); | |
1da177e4 LT |
885 | |
886 | kfree(tag_index); | |
887 | kfree(tag_map); | |
888 | return 0; | |
889 | } | |
890 | ||
891 | EXPORT_SYMBOL(blk_queue_resize_tags); | |
892 | ||
893 | /** | |
894 | * blk_queue_end_tag - end tag operations for a request | |
895 | * @q: the request queue for the device | |
896 | * @rq: the request that has completed | |
897 | * | |
898 | * Description: | |
899 | * Typically called when end_that_request_first() returns 0, meaning | |
900 | * all transfers have been done for a request. It's important to call | |
901 | * this function before end_that_request_last(), as that will put the | |
902 | * request back on the free list thus corrupting the internal tag list. | |
903 | * | |
904 | * Notes: | |
905 | * queue lock must be held. | |
906 | **/ | |
907 | void blk_queue_end_tag(request_queue_t *q, struct request *rq) | |
908 | { | |
909 | struct blk_queue_tag *bqt = q->queue_tags; | |
910 | int tag = rq->tag; | |
911 | ||
912 | BUG_ON(tag == -1); | |
913 | ||
fa72b903 | 914 | if (unlikely(tag >= bqt->max_depth)) |
1da177e4 LT |
915 | return; |
916 | ||
917 | if (unlikely(!__test_and_clear_bit(tag, bqt->tag_map))) { | |
918 | printk("attempt to clear non-busy tag (%d)\n", tag); | |
919 | return; | |
920 | } | |
921 | ||
922 | list_del_init(&rq->queuelist); | |
923 | rq->flags &= ~REQ_QUEUED; | |
924 | rq->tag = -1; | |
925 | ||
926 | if (unlikely(bqt->tag_index[tag] == NULL)) | |
927 | printk("tag %d is missing\n", tag); | |
928 | ||
929 | bqt->tag_index[tag] = NULL; | |
930 | bqt->busy--; | |
931 | } | |
932 | ||
933 | EXPORT_SYMBOL(blk_queue_end_tag); | |
934 | ||
935 | /** | |
936 | * blk_queue_start_tag - find a free tag and assign it | |
937 | * @q: the request queue for the device | |
938 | * @rq: the block request that needs tagging | |
939 | * | |
940 | * Description: | |
941 | * This can either be used as a stand-alone helper, or possibly be | |
942 | * assigned as the queue &prep_rq_fn (in which case &struct request | |
943 | * automagically gets a tag assigned). Note that this function | |
944 | * assumes that any type of request can be queued! if this is not | |
945 | * true for your device, you must check the request type before | |
946 | * calling this function. The request will also be removed from | |
947 | * the request queue, so it's the drivers responsibility to readd | |
948 | * it if it should need to be restarted for some reason. | |
949 | * | |
950 | * Notes: | |
951 | * queue lock must be held. | |
952 | **/ | |
953 | int blk_queue_start_tag(request_queue_t *q, struct request *rq) | |
954 | { | |
955 | struct blk_queue_tag *bqt = q->queue_tags; | |
2bf0fdad | 956 | int tag; |
1da177e4 LT |
957 | |
958 | if (unlikely((rq->flags & REQ_QUEUED))) { | |
959 | printk(KERN_ERR | |
960 | "request %p for device [%s] already tagged %d", | |
961 | rq, rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->tag); | |
962 | BUG(); | |
963 | } | |
964 | ||
2bf0fdad TH |
965 | tag = find_first_zero_bit(bqt->tag_map, bqt->max_depth); |
966 | if (tag >= bqt->max_depth) | |
967 | return 1; | |
1da177e4 | 968 | |
1da177e4 LT |
969 | __set_bit(tag, bqt->tag_map); |
970 | ||
971 | rq->flags |= REQ_QUEUED; | |
972 | rq->tag = tag; | |
973 | bqt->tag_index[tag] = rq; | |
974 | blkdev_dequeue_request(rq); | |
975 | list_add(&rq->queuelist, &bqt->busy_list); | |
976 | bqt->busy++; | |
977 | return 0; | |
978 | } | |
979 | ||
980 | EXPORT_SYMBOL(blk_queue_start_tag); | |
981 | ||
982 | /** | |
983 | * blk_queue_invalidate_tags - invalidate all pending tags | |
984 | * @q: the request queue for the device | |
985 | * | |
986 | * Description: | |
987 | * Hardware conditions may dictate a need to stop all pending requests. | |
988 | * In this case, we will safely clear the block side of the tag queue and | |
989 | * readd all requests to the request queue in the right order. | |
990 | * | |
991 | * Notes: | |
992 | * queue lock must be held. | |
993 | **/ | |
994 | void blk_queue_invalidate_tags(request_queue_t *q) | |
995 | { | |
996 | struct blk_queue_tag *bqt = q->queue_tags; | |
997 | struct list_head *tmp, *n; | |
998 | struct request *rq; | |
999 | ||
1000 | list_for_each_safe(tmp, n, &bqt->busy_list) { | |
1001 | rq = list_entry_rq(tmp); | |
1002 | ||
1003 | if (rq->tag == -1) { | |
1004 | printk("bad tag found on list\n"); | |
1005 | list_del_init(&rq->queuelist); | |
1006 | rq->flags &= ~REQ_QUEUED; | |
1007 | } else | |
1008 | blk_queue_end_tag(q, rq); | |
1009 | ||
1010 | rq->flags &= ~REQ_STARTED; | |
1011 | __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0); | |
1012 | } | |
1013 | } | |
1014 | ||
1015 | EXPORT_SYMBOL(blk_queue_invalidate_tags); | |
1016 | ||
1017 | static char *rq_flags[] = { | |
1018 | "REQ_RW", | |
1019 | "REQ_FAILFAST", | |
1020 | "REQ_SOFTBARRIER", | |
1021 | "REQ_HARDBARRIER", | |
1022 | "REQ_CMD", | |
1023 | "REQ_NOMERGE", | |
1024 | "REQ_STARTED", | |
1025 | "REQ_DONTPREP", | |
1026 | "REQ_QUEUED", | |
1027 | "REQ_PC", | |
1028 | "REQ_BLOCK_PC", | |
1029 | "REQ_SENSE", | |
1030 | "REQ_FAILED", | |
1031 | "REQ_QUIET", | |
1032 | "REQ_SPECIAL", | |
1033 | "REQ_DRIVE_CMD", | |
1034 | "REQ_DRIVE_TASK", | |
1035 | "REQ_DRIVE_TASKFILE", | |
1036 | "REQ_PREEMPT", | |
1037 | "REQ_PM_SUSPEND", | |
1038 | "REQ_PM_RESUME", | |
1039 | "REQ_PM_SHUTDOWN", | |
1040 | }; | |
1041 | ||
1042 | void blk_dump_rq_flags(struct request *rq, char *msg) | |
1043 | { | |
1044 | int bit; | |
1045 | ||
1046 | printk("%s: dev %s: flags = ", msg, | |
1047 | rq->rq_disk ? rq->rq_disk->disk_name : "?"); | |
1048 | bit = 0; | |
1049 | do { | |
1050 | if (rq->flags & (1 << bit)) | |
1051 | printk("%s ", rq_flags[bit]); | |
1052 | bit++; | |
1053 | } while (bit < __REQ_NR_BITS); | |
1054 | ||
1055 | printk("\nsector %llu, nr/cnr %lu/%u\n", (unsigned long long)rq->sector, | |
1056 | rq->nr_sectors, | |
1057 | rq->current_nr_sectors); | |
1058 | printk("bio %p, biotail %p, buffer %p, data %p, len %u\n", rq->bio, rq->biotail, rq->buffer, rq->data, rq->data_len); | |
1059 | ||
1060 | if (rq->flags & (REQ_BLOCK_PC | REQ_PC)) { | |
1061 | printk("cdb: "); | |
1062 | for (bit = 0; bit < sizeof(rq->cmd); bit++) | |
1063 | printk("%02x ", rq->cmd[bit]); | |
1064 | printk("\n"); | |
1065 | } | |
1066 | } | |
1067 | ||
1068 | EXPORT_SYMBOL(blk_dump_rq_flags); | |
1069 | ||
1070 | void blk_recount_segments(request_queue_t *q, struct bio *bio) | |
1071 | { | |
1072 | struct bio_vec *bv, *bvprv = NULL; | |
1073 | int i, nr_phys_segs, nr_hw_segs, seg_size, hw_seg_size, cluster; | |
1074 | int high, highprv = 1; | |
1075 | ||
1076 | if (unlikely(!bio->bi_io_vec)) | |
1077 | return; | |
1078 | ||
1079 | cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER); | |
1080 | hw_seg_size = seg_size = nr_phys_segs = nr_hw_segs = 0; | |
1081 | bio_for_each_segment(bv, bio, i) { | |
1082 | /* | |
1083 | * the trick here is making sure that a high page is never | |
1084 | * considered part of another segment, since that might | |
1085 | * change with the bounce page. | |
1086 | */ | |
1087 | high = page_to_pfn(bv->bv_page) >= q->bounce_pfn; | |
1088 | if (high || highprv) | |
1089 | goto new_hw_segment; | |
1090 | if (cluster) { | |
1091 | if (seg_size + bv->bv_len > q->max_segment_size) | |
1092 | goto new_segment; | |
1093 | if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv)) | |
1094 | goto new_segment; | |
1095 | if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv)) | |
1096 | goto new_segment; | |
1097 | if (BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len)) | |
1098 | goto new_hw_segment; | |
1099 | ||
1100 | seg_size += bv->bv_len; | |
1101 | hw_seg_size += bv->bv_len; | |
1102 | bvprv = bv; | |
1103 | continue; | |
1104 | } | |
1105 | new_segment: | |
1106 | if (BIOVEC_VIRT_MERGEABLE(bvprv, bv) && | |
1107 | !BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len)) { | |
1108 | hw_seg_size += bv->bv_len; | |
1109 | } else { | |
1110 | new_hw_segment: | |
1111 | if (hw_seg_size > bio->bi_hw_front_size) | |
1112 | bio->bi_hw_front_size = hw_seg_size; | |
1113 | hw_seg_size = BIOVEC_VIRT_START_SIZE(bv) + bv->bv_len; | |
1114 | nr_hw_segs++; | |
1115 | } | |
1116 | ||
1117 | nr_phys_segs++; | |
1118 | bvprv = bv; | |
1119 | seg_size = bv->bv_len; | |
1120 | highprv = high; | |
1121 | } | |
1122 | if (hw_seg_size > bio->bi_hw_back_size) | |
1123 | bio->bi_hw_back_size = hw_seg_size; | |
1124 | if (nr_hw_segs == 1 && hw_seg_size > bio->bi_hw_front_size) | |
1125 | bio->bi_hw_front_size = hw_seg_size; | |
1126 | bio->bi_phys_segments = nr_phys_segs; | |
1127 | bio->bi_hw_segments = nr_hw_segs; | |
1128 | bio->bi_flags |= (1 << BIO_SEG_VALID); | |
1129 | } | |
1130 | ||
1131 | ||
1132 | int blk_phys_contig_segment(request_queue_t *q, struct bio *bio, | |
1133 | struct bio *nxt) | |
1134 | { | |
1135 | if (!(q->queue_flags & (1 << QUEUE_FLAG_CLUSTER))) | |
1136 | return 0; | |
1137 | ||
1138 | if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt))) | |
1139 | return 0; | |
1140 | if (bio->bi_size + nxt->bi_size > q->max_segment_size) | |
1141 | return 0; | |
1142 | ||
1143 | /* | |
1144 | * bio and nxt are contigous in memory, check if the queue allows | |
1145 | * these two to be merged into one | |
1146 | */ | |
1147 | if (BIO_SEG_BOUNDARY(q, bio, nxt)) | |
1148 | return 1; | |
1149 | ||
1150 | return 0; | |
1151 | } | |
1152 | ||
1153 | EXPORT_SYMBOL(blk_phys_contig_segment); | |
1154 | ||
1155 | int blk_hw_contig_segment(request_queue_t *q, struct bio *bio, | |
1156 | struct bio *nxt) | |
1157 | { | |
1158 | if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) | |
1159 | blk_recount_segments(q, bio); | |
1160 | if (unlikely(!bio_flagged(nxt, BIO_SEG_VALID))) | |
1161 | blk_recount_segments(q, nxt); | |
1162 | if (!BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)) || | |
1163 | BIOVEC_VIRT_OVERSIZE(bio->bi_hw_front_size + bio->bi_hw_back_size)) | |
1164 | return 0; | |
1165 | if (bio->bi_size + nxt->bi_size > q->max_segment_size) | |
1166 | return 0; | |
1167 | ||
1168 | return 1; | |
1169 | } | |
1170 | ||
1171 | EXPORT_SYMBOL(blk_hw_contig_segment); | |
1172 | ||
1173 | /* | |
1174 | * map a request to scatterlist, return number of sg entries setup. Caller | |
1175 | * must make sure sg can hold rq->nr_phys_segments entries | |
1176 | */ | |
1177 | int blk_rq_map_sg(request_queue_t *q, struct request *rq, struct scatterlist *sg) | |
1178 | { | |
1179 | struct bio_vec *bvec, *bvprv; | |
1180 | struct bio *bio; | |
1181 | int nsegs, i, cluster; | |
1182 | ||
1183 | nsegs = 0; | |
1184 | cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER); | |
1185 | ||
1186 | /* | |
1187 | * for each bio in rq | |
1188 | */ | |
1189 | bvprv = NULL; | |
1190 | rq_for_each_bio(bio, rq) { | |
1191 | /* | |
1192 | * for each segment in bio | |
1193 | */ | |
1194 | bio_for_each_segment(bvec, bio, i) { | |
1195 | int nbytes = bvec->bv_len; | |
1196 | ||
1197 | if (bvprv && cluster) { | |
1198 | if (sg[nsegs - 1].length + nbytes > q->max_segment_size) | |
1199 | goto new_segment; | |
1200 | ||
1201 | if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) | |
1202 | goto new_segment; | |
1203 | if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec)) | |
1204 | goto new_segment; | |
1205 | ||
1206 | sg[nsegs - 1].length += nbytes; | |
1207 | } else { | |
1208 | new_segment: | |
1209 | memset(&sg[nsegs],0,sizeof(struct scatterlist)); | |
1210 | sg[nsegs].page = bvec->bv_page; | |
1211 | sg[nsegs].length = nbytes; | |
1212 | sg[nsegs].offset = bvec->bv_offset; | |
1213 | ||
1214 | nsegs++; | |
1215 | } | |
1216 | bvprv = bvec; | |
1217 | } /* segments in bio */ | |
1218 | } /* bios in rq */ | |
1219 | ||
1220 | return nsegs; | |
1221 | } | |
1222 | ||
1223 | EXPORT_SYMBOL(blk_rq_map_sg); | |
1224 | ||
1225 | /* | |
1226 | * the standard queue merge functions, can be overridden with device | |
1227 | * specific ones if so desired | |
1228 | */ | |
1229 | ||
1230 | static inline int ll_new_mergeable(request_queue_t *q, | |
1231 | struct request *req, | |
1232 | struct bio *bio) | |
1233 | { | |
1234 | int nr_phys_segs = bio_phys_segments(q, bio); | |
1235 | ||
1236 | if (req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) { | |
1237 | req->flags |= REQ_NOMERGE; | |
1238 | if (req == q->last_merge) | |
1239 | q->last_merge = NULL; | |
1240 | return 0; | |
1241 | } | |
1242 | ||
1243 | /* | |
1244 | * A hw segment is just getting larger, bump just the phys | |
1245 | * counter. | |
1246 | */ | |
1247 | req->nr_phys_segments += nr_phys_segs; | |
1248 | return 1; | |
1249 | } | |
1250 | ||
1251 | static inline int ll_new_hw_segment(request_queue_t *q, | |
1252 | struct request *req, | |
1253 | struct bio *bio) | |
1254 | { | |
1255 | int nr_hw_segs = bio_hw_segments(q, bio); | |
1256 | int nr_phys_segs = bio_phys_segments(q, bio); | |
1257 | ||
1258 | if (req->nr_hw_segments + nr_hw_segs > q->max_hw_segments | |
1259 | || req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) { | |
1260 | req->flags |= REQ_NOMERGE; | |
1261 | if (req == q->last_merge) | |
1262 | q->last_merge = NULL; | |
1263 | return 0; | |
1264 | } | |
1265 | ||
1266 | /* | |
1267 | * This will form the start of a new hw segment. Bump both | |
1268 | * counters. | |
1269 | */ | |
1270 | req->nr_hw_segments += nr_hw_segs; | |
1271 | req->nr_phys_segments += nr_phys_segs; | |
1272 | return 1; | |
1273 | } | |
1274 | ||
1275 | static int ll_back_merge_fn(request_queue_t *q, struct request *req, | |
1276 | struct bio *bio) | |
1277 | { | |
1278 | int len; | |
1279 | ||
1280 | if (req->nr_sectors + bio_sectors(bio) > q->max_sectors) { | |
1281 | req->flags |= REQ_NOMERGE; | |
1282 | if (req == q->last_merge) | |
1283 | q->last_merge = NULL; | |
1284 | return 0; | |
1285 | } | |
1286 | if (unlikely(!bio_flagged(req->biotail, BIO_SEG_VALID))) | |
1287 | blk_recount_segments(q, req->biotail); | |
1288 | if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) | |
1289 | blk_recount_segments(q, bio); | |
1290 | len = req->biotail->bi_hw_back_size + bio->bi_hw_front_size; | |
1291 | if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req->biotail), __BVEC_START(bio)) && | |
1292 | !BIOVEC_VIRT_OVERSIZE(len)) { | |
1293 | int mergeable = ll_new_mergeable(q, req, bio); | |
1294 | ||
1295 | if (mergeable) { | |
1296 | if (req->nr_hw_segments == 1) | |
1297 | req->bio->bi_hw_front_size = len; | |
1298 | if (bio->bi_hw_segments == 1) | |
1299 | bio->bi_hw_back_size = len; | |
1300 | } | |
1301 | return mergeable; | |
1302 | } | |
1303 | ||
1304 | return ll_new_hw_segment(q, req, bio); | |
1305 | } | |
1306 | ||
1307 | static int ll_front_merge_fn(request_queue_t *q, struct request *req, | |
1308 | struct bio *bio) | |
1309 | { | |
1310 | int len; | |
1311 | ||
1312 | if (req->nr_sectors + bio_sectors(bio) > q->max_sectors) { | |
1313 | req->flags |= REQ_NOMERGE; | |
1314 | if (req == q->last_merge) | |
1315 | q->last_merge = NULL; | |
1316 | return 0; | |
1317 | } | |
1318 | len = bio->bi_hw_back_size + req->bio->bi_hw_front_size; | |
1319 | if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) | |
1320 | blk_recount_segments(q, bio); | |
1321 | if (unlikely(!bio_flagged(req->bio, BIO_SEG_VALID))) | |
1322 | blk_recount_segments(q, req->bio); | |
1323 | if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(req->bio)) && | |
1324 | !BIOVEC_VIRT_OVERSIZE(len)) { | |
1325 | int mergeable = ll_new_mergeable(q, req, bio); | |
1326 | ||
1327 | if (mergeable) { | |
1328 | if (bio->bi_hw_segments == 1) | |
1329 | bio->bi_hw_front_size = len; | |
1330 | if (req->nr_hw_segments == 1) | |
1331 | req->biotail->bi_hw_back_size = len; | |
1332 | } | |
1333 | return mergeable; | |
1334 | } | |
1335 | ||
1336 | return ll_new_hw_segment(q, req, bio); | |
1337 | } | |
1338 | ||
1339 | static int ll_merge_requests_fn(request_queue_t *q, struct request *req, | |
1340 | struct request *next) | |
1341 | { | |
1342 | int total_phys_segments = req->nr_phys_segments +next->nr_phys_segments; | |
1343 | int total_hw_segments = req->nr_hw_segments + next->nr_hw_segments; | |
1344 | ||
1345 | /* | |
1346 | * First check if the either of the requests are re-queued | |
1347 | * requests. Can't merge them if they are. | |
1348 | */ | |
1349 | if (req->special || next->special) | |
1350 | return 0; | |
1351 | ||
1352 | /* | |
1353 | * Will it become to large? | |
1354 | */ | |
1355 | if ((req->nr_sectors + next->nr_sectors) > q->max_sectors) | |
1356 | return 0; | |
1357 | ||
1358 | total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; | |
1359 | if (blk_phys_contig_segment(q, req->biotail, next->bio)) | |
1360 | total_phys_segments--; | |
1361 | ||
1362 | if (total_phys_segments > q->max_phys_segments) | |
1363 | return 0; | |
1364 | ||
1365 | total_hw_segments = req->nr_hw_segments + next->nr_hw_segments; | |
1366 | if (blk_hw_contig_segment(q, req->biotail, next->bio)) { | |
1367 | int len = req->biotail->bi_hw_back_size + next->bio->bi_hw_front_size; | |
1368 | /* | |
1369 | * propagate the combined length to the end of the requests | |
1370 | */ | |
1371 | if (req->nr_hw_segments == 1) | |
1372 | req->bio->bi_hw_front_size = len; | |
1373 | if (next->nr_hw_segments == 1) | |
1374 | next->biotail->bi_hw_back_size = len; | |
1375 | total_hw_segments--; | |
1376 | } | |
1377 | ||
1378 | if (total_hw_segments > q->max_hw_segments) | |
1379 | return 0; | |
1380 | ||
1381 | /* Merge is OK... */ | |
1382 | req->nr_phys_segments = total_phys_segments; | |
1383 | req->nr_hw_segments = total_hw_segments; | |
1384 | return 1; | |
1385 | } | |
1386 | ||
1387 | /* | |
1388 | * "plug" the device if there are no outstanding requests: this will | |
1389 | * force the transfer to start only after we have put all the requests | |
1390 | * on the list. | |
1391 | * | |
1392 | * This is called with interrupts off and no requests on the queue and | |
1393 | * with the queue lock held. | |
1394 | */ | |
1395 | void blk_plug_device(request_queue_t *q) | |
1396 | { | |
1397 | WARN_ON(!irqs_disabled()); | |
1398 | ||
1399 | /* | |
1400 | * don't plug a stopped queue, it must be paired with blk_start_queue() | |
1401 | * which will restart the queueing | |
1402 | */ | |
1403 | if (test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags)) | |
1404 | return; | |
1405 | ||
1406 | if (!test_and_set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) | |
1407 | mod_timer(&q->unplug_timer, jiffies + q->unplug_delay); | |
1408 | } | |
1409 | ||
1410 | EXPORT_SYMBOL(blk_plug_device); | |
1411 | ||
1412 | /* | |
1413 | * remove the queue from the plugged list, if present. called with | |
1414 | * queue lock held and interrupts disabled. | |
1415 | */ | |
1416 | int blk_remove_plug(request_queue_t *q) | |
1417 | { | |
1418 | WARN_ON(!irqs_disabled()); | |
1419 | ||
1420 | if (!test_and_clear_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) | |
1421 | return 0; | |
1422 | ||
1423 | del_timer(&q->unplug_timer); | |
1424 | return 1; | |
1425 | } | |
1426 | ||
1427 | EXPORT_SYMBOL(blk_remove_plug); | |
1428 | ||
1429 | /* | |
1430 | * remove the plug and let it rip.. | |
1431 | */ | |
1432 | void __generic_unplug_device(request_queue_t *q) | |
1433 | { | |
1434 | if (test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags)) | |
1435 | return; | |
1436 | ||
1437 | if (!blk_remove_plug(q)) | |
1438 | return; | |
1439 | ||
1440 | /* | |
1441 | * was plugged, fire request_fn if queue has stuff to do | |
1442 | */ | |
1443 | if (elv_next_request(q)) | |
1444 | q->request_fn(q); | |
1445 | } | |
1446 | EXPORT_SYMBOL(__generic_unplug_device); | |
1447 | ||
1448 | /** | |
1449 | * generic_unplug_device - fire a request queue | |
1450 | * @q: The &request_queue_t in question | |
1451 | * | |
1452 | * Description: | |
1453 | * Linux uses plugging to build bigger requests queues before letting | |
1454 | * the device have at them. If a queue is plugged, the I/O scheduler | |
1455 | * is still adding and merging requests on the queue. Once the queue | |
1456 | * gets unplugged, the request_fn defined for the queue is invoked and | |
1457 | * transfers started. | |
1458 | **/ | |
1459 | void generic_unplug_device(request_queue_t *q) | |
1460 | { | |
1461 | spin_lock_irq(q->queue_lock); | |
1462 | __generic_unplug_device(q); | |
1463 | spin_unlock_irq(q->queue_lock); | |
1464 | } | |
1465 | EXPORT_SYMBOL(generic_unplug_device); | |
1466 | ||
1467 | static void blk_backing_dev_unplug(struct backing_dev_info *bdi, | |
1468 | struct page *page) | |
1469 | { | |
1470 | request_queue_t *q = bdi->unplug_io_data; | |
1471 | ||
1472 | /* | |
1473 | * devices don't necessarily have an ->unplug_fn defined | |
1474 | */ | |
1475 | if (q->unplug_fn) | |
1476 | q->unplug_fn(q); | |
1477 | } | |
1478 | ||
1479 | static void blk_unplug_work(void *data) | |
1480 | { | |
1481 | request_queue_t *q = data; | |
1482 | ||
1483 | q->unplug_fn(q); | |
1484 | } | |
1485 | ||
1486 | static void blk_unplug_timeout(unsigned long data) | |
1487 | { | |
1488 | request_queue_t *q = (request_queue_t *)data; | |
1489 | ||
1490 | kblockd_schedule_work(&q->unplug_work); | |
1491 | } | |
1492 | ||
1493 | /** | |
1494 | * blk_start_queue - restart a previously stopped queue | |
1495 | * @q: The &request_queue_t in question | |
1496 | * | |
1497 | * Description: | |
1498 | * blk_start_queue() will clear the stop flag on the queue, and call | |
1499 | * the request_fn for the queue if it was in a stopped state when | |
1500 | * entered. Also see blk_stop_queue(). Queue lock must be held. | |
1501 | **/ | |
1502 | void blk_start_queue(request_queue_t *q) | |
1503 | { | |
1504 | clear_bit(QUEUE_FLAG_STOPPED, &q->queue_flags); | |
1505 | ||
1506 | /* | |
1507 | * one level of recursion is ok and is much faster than kicking | |
1508 | * the unplug handling | |
1509 | */ | |
1510 | if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) { | |
1511 | q->request_fn(q); | |
1512 | clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags); | |
1513 | } else { | |
1514 | blk_plug_device(q); | |
1515 | kblockd_schedule_work(&q->unplug_work); | |
1516 | } | |
1517 | } | |
1518 | ||
1519 | EXPORT_SYMBOL(blk_start_queue); | |
1520 | ||
1521 | /** | |
1522 | * blk_stop_queue - stop a queue | |
1523 | * @q: The &request_queue_t in question | |
1524 | * | |
1525 | * Description: | |
1526 | * The Linux block layer assumes that a block driver will consume all | |
1527 | * entries on the request queue when the request_fn strategy is called. | |
1528 | * Often this will not happen, because of hardware limitations (queue | |
1529 | * depth settings). If a device driver gets a 'queue full' response, | |
1530 | * or if it simply chooses not to queue more I/O at one point, it can | |
1531 | * call this function to prevent the request_fn from being called until | |
1532 | * the driver has signalled it's ready to go again. This happens by calling | |
1533 | * blk_start_queue() to restart queue operations. Queue lock must be held. | |
1534 | **/ | |
1535 | void blk_stop_queue(request_queue_t *q) | |
1536 | { | |
1537 | blk_remove_plug(q); | |
1538 | set_bit(QUEUE_FLAG_STOPPED, &q->queue_flags); | |
1539 | } | |
1540 | EXPORT_SYMBOL(blk_stop_queue); | |
1541 | ||
1542 | /** | |
1543 | * blk_sync_queue - cancel any pending callbacks on a queue | |
1544 | * @q: the queue | |
1545 | * | |
1546 | * Description: | |
1547 | * The block layer may perform asynchronous callback activity | |
1548 | * on a queue, such as calling the unplug function after a timeout. | |
1549 | * A block device may call blk_sync_queue to ensure that any | |
1550 | * such activity is cancelled, thus allowing it to release resources | |
1551 | * the the callbacks might use. The caller must already have made sure | |
1552 | * that its ->make_request_fn will not re-add plugging prior to calling | |
1553 | * this function. | |
1554 | * | |
1555 | */ | |
1556 | void blk_sync_queue(struct request_queue *q) | |
1557 | { | |
1558 | del_timer_sync(&q->unplug_timer); | |
1559 | kblockd_flush(); | |
1560 | } | |
1561 | EXPORT_SYMBOL(blk_sync_queue); | |
1562 | ||
1563 | /** | |
1564 | * blk_run_queue - run a single device queue | |
1565 | * @q: The queue to run | |
1566 | */ | |
1567 | void blk_run_queue(struct request_queue *q) | |
1568 | { | |
1569 | unsigned long flags; | |
1570 | ||
1571 | spin_lock_irqsave(q->queue_lock, flags); | |
1572 | blk_remove_plug(q); | |
a2997382 KC |
1573 | if (!elv_queue_empty(q)) |
1574 | q->request_fn(q); | |
1da177e4 LT |
1575 | spin_unlock_irqrestore(q->queue_lock, flags); |
1576 | } | |
1577 | EXPORT_SYMBOL(blk_run_queue); | |
1578 | ||
1579 | /** | |
1580 | * blk_cleanup_queue: - release a &request_queue_t when it is no longer needed | |
1581 | * @q: the request queue to be released | |
1582 | * | |
1583 | * Description: | |
1584 | * blk_cleanup_queue is the pair to blk_init_queue() or | |
1585 | * blk_queue_make_request(). It should be called when a request queue is | |
1586 | * being released; typically when a block device is being de-registered. | |
1587 | * Currently, its primary task it to free all the &struct request | |
1588 | * structures that were allocated to the queue and the queue itself. | |
1589 | * | |
1590 | * Caveat: | |
1591 | * Hopefully the low level driver will have finished any | |
1592 | * outstanding requests first... | |
1593 | **/ | |
1594 | void blk_cleanup_queue(request_queue_t * q) | |
1595 | { | |
1596 | struct request_list *rl = &q->rq; | |
1597 | ||
1598 | if (!atomic_dec_and_test(&q->refcnt)) | |
1599 | return; | |
1600 | ||
1601 | if (q->elevator) | |
1602 | elevator_exit(q->elevator); | |
1603 | ||
1604 | blk_sync_queue(q); | |
1605 | ||
1606 | if (rl->rq_pool) | |
1607 | mempool_destroy(rl->rq_pool); | |
1608 | ||
1609 | if (q->queue_tags) | |
1610 | __blk_queue_free_tags(q); | |
1611 | ||
1612 | blk_queue_ordered(q, QUEUE_ORDERED_NONE); | |
1613 | ||
1614 | kmem_cache_free(requestq_cachep, q); | |
1615 | } | |
1616 | ||
1617 | EXPORT_SYMBOL(blk_cleanup_queue); | |
1618 | ||
1619 | static int blk_init_free_list(request_queue_t *q) | |
1620 | { | |
1621 | struct request_list *rl = &q->rq; | |
1622 | ||
1623 | rl->count[READ] = rl->count[WRITE] = 0; | |
1624 | rl->starved[READ] = rl->starved[WRITE] = 0; | |
1625 | init_waitqueue_head(&rl->wait[READ]); | |
1626 | init_waitqueue_head(&rl->wait[WRITE]); | |
1627 | init_waitqueue_head(&rl->drain); | |
1628 | ||
1946089a CL |
1629 | rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab, |
1630 | mempool_free_slab, request_cachep, q->node); | |
1da177e4 LT |
1631 | |
1632 | if (!rl->rq_pool) | |
1633 | return -ENOMEM; | |
1634 | ||
1635 | return 0; | |
1636 | } | |
1637 | ||
1638 | static int __make_request(request_queue_t *, struct bio *); | |
1639 | ||
1640 | request_queue_t *blk_alloc_queue(int gfp_mask) | |
1641 | { | |
1946089a CL |
1642 | return blk_alloc_queue_node(gfp_mask, -1); |
1643 | } | |
1644 | EXPORT_SYMBOL(blk_alloc_queue); | |
1da177e4 | 1645 | |
1946089a CL |
1646 | request_queue_t *blk_alloc_queue_node(int gfp_mask, int node_id) |
1647 | { | |
1648 | request_queue_t *q; | |
1649 | ||
1650 | q = kmem_cache_alloc_node(requestq_cachep, gfp_mask, node_id); | |
1da177e4 LT |
1651 | if (!q) |
1652 | return NULL; | |
1653 | ||
1654 | memset(q, 0, sizeof(*q)); | |
1655 | init_timer(&q->unplug_timer); | |
1656 | atomic_set(&q->refcnt, 1); | |
1657 | ||
1658 | q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug; | |
1659 | q->backing_dev_info.unplug_io_data = q; | |
1660 | ||
1661 | return q; | |
1662 | } | |
1946089a | 1663 | EXPORT_SYMBOL(blk_alloc_queue_node); |
1da177e4 LT |
1664 | |
1665 | /** | |
1666 | * blk_init_queue - prepare a request queue for use with a block device | |
1667 | * @rfn: The function to be called to process requests that have been | |
1668 | * placed on the queue. | |
1669 | * @lock: Request queue spin lock | |
1670 | * | |
1671 | * Description: | |
1672 | * If a block device wishes to use the standard request handling procedures, | |
1673 | * which sorts requests and coalesces adjacent requests, then it must | |
1674 | * call blk_init_queue(). The function @rfn will be called when there | |
1675 | * are requests on the queue that need to be processed. If the device | |
1676 | * supports plugging, then @rfn may not be called immediately when requests | |
1677 | * are available on the queue, but may be called at some time later instead. | |
1678 | * Plugged queues are generally unplugged when a buffer belonging to one | |
1679 | * of the requests on the queue is needed, or due to memory pressure. | |
1680 | * | |
1681 | * @rfn is not required, or even expected, to remove all requests off the | |
1682 | * queue, but only as many as it can handle at a time. If it does leave | |
1683 | * requests on the queue, it is responsible for arranging that the requests | |
1684 | * get dealt with eventually. | |
1685 | * | |
1686 | * The queue spin lock must be held while manipulating the requests on the | |
1687 | * request queue. | |
1688 | * | |
1689 | * Function returns a pointer to the initialized request queue, or NULL if | |
1690 | * it didn't succeed. | |
1691 | * | |
1692 | * Note: | |
1693 | * blk_init_queue() must be paired with a blk_cleanup_queue() call | |
1694 | * when the block device is deactivated (such as at module unload). | |
1695 | **/ | |
1946089a | 1696 | |
1da177e4 LT |
1697 | request_queue_t *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock) |
1698 | { | |
1946089a CL |
1699 | return blk_init_queue_node(rfn, lock, -1); |
1700 | } | |
1701 | EXPORT_SYMBOL(blk_init_queue); | |
1702 | ||
1703 | request_queue_t * | |
1704 | blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id) | |
1705 | { | |
1706 | request_queue_t *q = blk_alloc_queue_node(GFP_KERNEL, node_id); | |
1da177e4 LT |
1707 | |
1708 | if (!q) | |
1709 | return NULL; | |
1710 | ||
1946089a | 1711 | q->node = node_id; |
1da177e4 LT |
1712 | if (blk_init_free_list(q)) |
1713 | goto out_init; | |
1714 | ||
152587de | 1715 | /* |
1716 | * if caller didn't supply a lock, they get per-queue locking with | |
1717 | * our embedded lock | |
1718 | */ | |
1719 | if (!lock) { | |
1720 | spin_lock_init(&q->__queue_lock); | |
1721 | lock = &q->__queue_lock; | |
1722 | } | |
1723 | ||
1da177e4 LT |
1724 | q->request_fn = rfn; |
1725 | q->back_merge_fn = ll_back_merge_fn; | |
1726 | q->front_merge_fn = ll_front_merge_fn; | |
1727 | q->merge_requests_fn = ll_merge_requests_fn; | |
1728 | q->prep_rq_fn = NULL; | |
1729 | q->unplug_fn = generic_unplug_device; | |
1730 | q->queue_flags = (1 << QUEUE_FLAG_CLUSTER); | |
1731 | q->queue_lock = lock; | |
1732 | ||
1733 | blk_queue_segment_boundary(q, 0xffffffff); | |
1734 | ||
1735 | blk_queue_make_request(q, __make_request); | |
1736 | blk_queue_max_segment_size(q, MAX_SEGMENT_SIZE); | |
1737 | ||
1738 | blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS); | |
1739 | blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS); | |
1740 | ||
1741 | /* | |
1742 | * all done | |
1743 | */ | |
1744 | if (!elevator_init(q, NULL)) { | |
1745 | blk_queue_congestion_threshold(q); | |
1746 | return q; | |
1747 | } | |
1748 | ||
1749 | blk_cleanup_queue(q); | |
1750 | out_init: | |
1751 | kmem_cache_free(requestq_cachep, q); | |
1752 | return NULL; | |
1753 | } | |
1946089a | 1754 | EXPORT_SYMBOL(blk_init_queue_node); |
1da177e4 LT |
1755 | |
1756 | int blk_get_queue(request_queue_t *q) | |
1757 | { | |
1758 | if (!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) { | |
1759 | atomic_inc(&q->refcnt); | |
1760 | return 0; | |
1761 | } | |
1762 | ||
1763 | return 1; | |
1764 | } | |
1765 | ||
1766 | EXPORT_SYMBOL(blk_get_queue); | |
1767 | ||
1768 | static inline void blk_free_request(request_queue_t *q, struct request *rq) | |
1769 | { | |
1770 | elv_put_request(q, rq); | |
1771 | mempool_free(rq, q->rq.rq_pool); | |
1772 | } | |
1773 | ||
1774 | static inline struct request *blk_alloc_request(request_queue_t *q, int rw, | |
1775 | int gfp_mask) | |
1776 | { | |
1777 | struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask); | |
1778 | ||
1779 | if (!rq) | |
1780 | return NULL; | |
1781 | ||
1782 | /* | |
1783 | * first three bits are identical in rq->flags and bio->bi_rw, | |
1784 | * see bio.h and blkdev.h | |
1785 | */ | |
1786 | rq->flags = rw; | |
1787 | ||
1788 | if (!elv_set_request(q, rq, gfp_mask)) | |
1789 | return rq; | |
1790 | ||
1791 | mempool_free(rq, q->rq.rq_pool); | |
1792 | return NULL; | |
1793 | } | |
1794 | ||
1795 | /* | |
1796 | * ioc_batching returns true if the ioc is a valid batching request and | |
1797 | * should be given priority access to a request. | |
1798 | */ | |
1799 | static inline int ioc_batching(request_queue_t *q, struct io_context *ioc) | |
1800 | { | |
1801 | if (!ioc) | |
1802 | return 0; | |
1803 | ||
1804 | /* | |
1805 | * Make sure the process is able to allocate at least 1 request | |
1806 | * even if the batch times out, otherwise we could theoretically | |
1807 | * lose wakeups. | |
1808 | */ | |
1809 | return ioc->nr_batch_requests == q->nr_batching || | |
1810 | (ioc->nr_batch_requests > 0 | |
1811 | && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME)); | |
1812 | } | |
1813 | ||
1814 | /* | |
1815 | * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This | |
1816 | * will cause the process to be a "batcher" on all queues in the system. This | |
1817 | * is the behaviour we want though - once it gets a wakeup it should be given | |
1818 | * a nice run. | |
1819 | */ | |
1820 | void ioc_set_batching(request_queue_t *q, struct io_context *ioc) | |
1821 | { | |
1822 | if (!ioc || ioc_batching(q, ioc)) | |
1823 | return; | |
1824 | ||
1825 | ioc->nr_batch_requests = q->nr_batching; | |
1826 | ioc->last_waited = jiffies; | |
1827 | } | |
1828 | ||
1829 | static void __freed_request(request_queue_t *q, int rw) | |
1830 | { | |
1831 | struct request_list *rl = &q->rq; | |
1832 | ||
1833 | if (rl->count[rw] < queue_congestion_off_threshold(q)) | |
1834 | clear_queue_congested(q, rw); | |
1835 | ||
1836 | if (rl->count[rw] + 1 <= q->nr_requests) { | |
1837 | smp_mb(); | |
1838 | if (waitqueue_active(&rl->wait[rw])) | |
1839 | wake_up(&rl->wait[rw]); | |
1840 | ||
1841 | blk_clear_queue_full(q, rw); | |
1842 | } | |
1843 | } | |
1844 | ||
1845 | /* | |
1846 | * A request has just been released. Account for it, update the full and | |
1847 | * congestion status, wake up any waiters. Called under q->queue_lock. | |
1848 | */ | |
1849 | static void freed_request(request_queue_t *q, int rw) | |
1850 | { | |
1851 | struct request_list *rl = &q->rq; | |
1852 | ||
1853 | rl->count[rw]--; | |
1854 | ||
1855 | __freed_request(q, rw); | |
1856 | ||
1857 | if (unlikely(rl->starved[rw ^ 1])) | |
1858 | __freed_request(q, rw ^ 1); | |
1859 | ||
1860 | if (!rl->count[READ] && !rl->count[WRITE]) { | |
1861 | smp_mb(); | |
1862 | if (unlikely(waitqueue_active(&rl->drain))) | |
1863 | wake_up(&rl->drain); | |
1864 | } | |
1865 | } | |
1866 | ||
1867 | #define blkdev_free_rq(list) list_entry((list)->next, struct request, queuelist) | |
1868 | /* | |
1869 | * Get a free request, queue_lock must not be held | |
1870 | */ | |
1871 | static struct request *get_request(request_queue_t *q, int rw, int gfp_mask) | |
1872 | { | |
1873 | struct request *rq = NULL; | |
1874 | struct request_list *rl = &q->rq; | |
1875 | struct io_context *ioc = get_io_context(gfp_mask); | |
1876 | ||
1877 | if (unlikely(test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags))) | |
1878 | goto out; | |
1879 | ||
1880 | spin_lock_irq(q->queue_lock); | |
1881 | if (rl->count[rw]+1 >= q->nr_requests) { | |
1882 | /* | |
1883 | * The queue will fill after this allocation, so set it as | |
1884 | * full, and mark this process as "batching". This process | |
1885 | * will be allowed to complete a batch of requests, others | |
1886 | * will be blocked. | |
1887 | */ | |
1888 | if (!blk_queue_full(q, rw)) { | |
1889 | ioc_set_batching(q, ioc); | |
1890 | blk_set_queue_full(q, rw); | |
1891 | } | |
1892 | } | |
1893 | ||
1894 | switch (elv_may_queue(q, rw)) { | |
1895 | case ELV_MQUEUE_NO: | |
1896 | goto rq_starved; | |
1897 | case ELV_MQUEUE_MAY: | |
1898 | break; | |
1899 | case ELV_MQUEUE_MUST: | |
1900 | goto get_rq; | |
1901 | } | |
1902 | ||
1903 | if (blk_queue_full(q, rw) && !ioc_batching(q, ioc)) { | |
1904 | /* | |
1905 | * The queue is full and the allocating process is not a | |
1906 | * "batcher", and not exempted by the IO scheduler | |
1907 | */ | |
1908 | spin_unlock_irq(q->queue_lock); | |
1909 | goto out; | |
1910 | } | |
1911 | ||
1912 | get_rq: | |
1913 | rl->count[rw]++; | |
1914 | rl->starved[rw] = 0; | |
1915 | if (rl->count[rw] >= queue_congestion_on_threshold(q)) | |
1916 | set_queue_congested(q, rw); | |
1917 | spin_unlock_irq(q->queue_lock); | |
1918 | ||
1919 | rq = blk_alloc_request(q, rw, gfp_mask); | |
1920 | if (!rq) { | |
1921 | /* | |
1922 | * Allocation failed presumably due to memory. Undo anything | |
1923 | * we might have messed up. | |
1924 | * | |
1925 | * Allocating task should really be put onto the front of the | |
1926 | * wait queue, but this is pretty rare. | |
1927 | */ | |
1928 | spin_lock_irq(q->queue_lock); | |
1929 | freed_request(q, rw); | |
1930 | ||
1931 | /* | |
1932 | * in the very unlikely event that allocation failed and no | |
1933 | * requests for this direction was pending, mark us starved | |
1934 | * so that freeing of a request in the other direction will | |
1935 | * notice us. another possible fix would be to split the | |
1936 | * rq mempool into READ and WRITE | |
1937 | */ | |
1938 | rq_starved: | |
1939 | if (unlikely(rl->count[rw] == 0)) | |
1940 | rl->starved[rw] = 1; | |
1941 | ||
1942 | spin_unlock_irq(q->queue_lock); | |
1943 | goto out; | |
1944 | } | |
1945 | ||
1946 | if (ioc_batching(q, ioc)) | |
1947 | ioc->nr_batch_requests--; | |
1948 | ||
1949 | rq_init(q, rq); | |
1950 | rq->rl = rl; | |
1951 | out: | |
1952 | put_io_context(ioc); | |
1953 | return rq; | |
1954 | } | |
1955 | ||
1956 | /* | |
1957 | * No available requests for this queue, unplug the device and wait for some | |
1958 | * requests to become available. | |
1959 | */ | |
1960 | static struct request *get_request_wait(request_queue_t *q, int rw) | |
1961 | { | |
1962 | DEFINE_WAIT(wait); | |
1963 | struct request *rq; | |
1964 | ||
1965 | generic_unplug_device(q); | |
1966 | do { | |
1967 | struct request_list *rl = &q->rq; | |
1968 | ||
1969 | prepare_to_wait_exclusive(&rl->wait[rw], &wait, | |
1970 | TASK_UNINTERRUPTIBLE); | |
1971 | ||
1972 | rq = get_request(q, rw, GFP_NOIO); | |
1973 | ||
1974 | if (!rq) { | |
1975 | struct io_context *ioc; | |
1976 | ||
1977 | io_schedule(); | |
1978 | ||
1979 | /* | |
1980 | * After sleeping, we become a "batching" process and | |
1981 | * will be able to allocate at least one request, and | |
1982 | * up to a big batch of them for a small period time. | |
1983 | * See ioc_batching, ioc_set_batching | |
1984 | */ | |
1985 | ioc = get_io_context(GFP_NOIO); | |
1986 | ioc_set_batching(q, ioc); | |
1987 | put_io_context(ioc); | |
1988 | } | |
1989 | finish_wait(&rl->wait[rw], &wait); | |
1990 | } while (!rq); | |
1991 | ||
1992 | return rq; | |
1993 | } | |
1994 | ||
1995 | struct request *blk_get_request(request_queue_t *q, int rw, int gfp_mask) | |
1996 | { | |
1997 | struct request *rq; | |
1998 | ||
1999 | BUG_ON(rw != READ && rw != WRITE); | |
2000 | ||
2001 | if (gfp_mask & __GFP_WAIT) | |
2002 | rq = get_request_wait(q, rw); | |
2003 | else | |
2004 | rq = get_request(q, rw, gfp_mask); | |
2005 | ||
2006 | return rq; | |
2007 | } | |
2008 | ||
2009 | EXPORT_SYMBOL(blk_get_request); | |
2010 | ||
2011 | /** | |
2012 | * blk_requeue_request - put a request back on queue | |
2013 | * @q: request queue where request should be inserted | |
2014 | * @rq: request to be inserted | |
2015 | * | |
2016 | * Description: | |
2017 | * Drivers often keep queueing requests until the hardware cannot accept | |
2018 | * more, when that condition happens we need to put the request back | |
2019 | * on the queue. Must be called with queue lock held. | |
2020 | */ | |
2021 | void blk_requeue_request(request_queue_t *q, struct request *rq) | |
2022 | { | |
2023 | if (blk_rq_tagged(rq)) | |
2024 | blk_queue_end_tag(q, rq); | |
2025 | ||
2026 | elv_requeue_request(q, rq); | |
2027 | } | |
2028 | ||
2029 | EXPORT_SYMBOL(blk_requeue_request); | |
2030 | ||
2031 | /** | |
2032 | * blk_insert_request - insert a special request in to a request queue | |
2033 | * @q: request queue where request should be inserted | |
2034 | * @rq: request to be inserted | |
2035 | * @at_head: insert request at head or tail of queue | |
2036 | * @data: private data | |
1da177e4 LT |
2037 | * |
2038 | * Description: | |
2039 | * Many block devices need to execute commands asynchronously, so they don't | |
2040 | * block the whole kernel from preemption during request execution. This is | |
2041 | * accomplished normally by inserting aritficial requests tagged as | |
2042 | * REQ_SPECIAL in to the corresponding request queue, and letting them be | |
2043 | * scheduled for actual execution by the request queue. | |
2044 | * | |
2045 | * We have the option of inserting the head or the tail of the queue. | |
2046 | * Typically we use the tail for new ioctls and so forth. We use the head | |
2047 | * of the queue for things like a QUEUE_FULL message from a device, or a | |
2048 | * host that is unable to accept a particular command. | |
2049 | */ | |
2050 | void blk_insert_request(request_queue_t *q, struct request *rq, | |
867d1191 | 2051 | int at_head, void *data) |
1da177e4 | 2052 | { |
867d1191 | 2053 | int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK; |
1da177e4 LT |
2054 | unsigned long flags; |
2055 | ||
2056 | /* | |
2057 | * tell I/O scheduler that this isn't a regular read/write (ie it | |
2058 | * must not attempt merges on this) and that it acts as a soft | |
2059 | * barrier | |
2060 | */ | |
2061 | rq->flags |= REQ_SPECIAL | REQ_SOFTBARRIER; | |
2062 | ||
2063 | rq->special = data; | |
2064 | ||
2065 | spin_lock_irqsave(q->queue_lock, flags); | |
2066 | ||
2067 | /* | |
2068 | * If command is tagged, release the tag | |
2069 | */ | |
867d1191 TH |
2070 | if (blk_rq_tagged(rq)) |
2071 | blk_queue_end_tag(q, rq); | |
1da177e4 | 2072 | |
867d1191 TH |
2073 | drive_stat_acct(rq, rq->nr_sectors, 1); |
2074 | __elv_add_request(q, rq, where, 0); | |
1da177e4 | 2075 | |
1da177e4 LT |
2076 | if (blk_queue_plugged(q)) |
2077 | __generic_unplug_device(q); | |
2078 | else | |
2079 | q->request_fn(q); | |
2080 | spin_unlock_irqrestore(q->queue_lock, flags); | |
2081 | } | |
2082 | ||
2083 | EXPORT_SYMBOL(blk_insert_request); | |
2084 | ||
2085 | /** | |
2086 | * blk_rq_map_user - map user data to a request, for REQ_BLOCK_PC usage | |
2087 | * @q: request queue where request should be inserted | |
2088 | * @rw: READ or WRITE data | |
2089 | * @ubuf: the user buffer | |
2090 | * @len: length of user data | |
2091 | * | |
2092 | * Description: | |
2093 | * Data will be mapped directly for zero copy io, if possible. Otherwise | |
2094 | * a kernel bounce buffer is used. | |
2095 | * | |
2096 | * A matching blk_rq_unmap_user() must be issued at the end of io, while | |
2097 | * still in process context. | |
2098 | * | |
2099 | * Note: The mapped bio may need to be bounced through blk_queue_bounce() | |
2100 | * before being submitted to the device, as pages mapped may be out of | |
2101 | * reach. It's the callers responsibility to make sure this happens. The | |
2102 | * original bio must be passed back in to blk_rq_unmap_user() for proper | |
2103 | * unmapping. | |
2104 | */ | |
2105 | struct request *blk_rq_map_user(request_queue_t *q, int rw, void __user *ubuf, | |
2106 | unsigned int len) | |
2107 | { | |
2108 | unsigned long uaddr; | |
2109 | struct request *rq; | |
2110 | struct bio *bio; | |
2111 | ||
2112 | if (len > (q->max_sectors << 9)) | |
2113 | return ERR_PTR(-EINVAL); | |
2114 | if ((!len && ubuf) || (len && !ubuf)) | |
2115 | return ERR_PTR(-EINVAL); | |
2116 | ||
2117 | rq = blk_get_request(q, rw, __GFP_WAIT); | |
2118 | if (!rq) | |
2119 | return ERR_PTR(-ENOMEM); | |
2120 | ||
2121 | /* | |
2122 | * if alignment requirement is satisfied, map in user pages for | |
2123 | * direct dma. else, set up kernel bounce buffers | |
2124 | */ | |
2125 | uaddr = (unsigned long) ubuf; | |
2126 | if (!(uaddr & queue_dma_alignment(q)) && !(len & queue_dma_alignment(q))) | |
2127 | bio = bio_map_user(q, NULL, uaddr, len, rw == READ); | |
2128 | else | |
2129 | bio = bio_copy_user(q, uaddr, len, rw == READ); | |
2130 | ||
2131 | if (!IS_ERR(bio)) { | |
2132 | rq->bio = rq->biotail = bio; | |
2133 | blk_rq_bio_prep(q, rq, bio); | |
2134 | ||
2135 | rq->buffer = rq->data = NULL; | |
2136 | rq->data_len = len; | |
2137 | return rq; | |
2138 | } | |
2139 | ||
2140 | /* | |
2141 | * bio is the err-ptr | |
2142 | */ | |
2143 | blk_put_request(rq); | |
2144 | return (struct request *) bio; | |
2145 | } | |
2146 | ||
2147 | EXPORT_SYMBOL(blk_rq_map_user); | |
2148 | ||
2149 | /** | |
2150 | * blk_rq_unmap_user - unmap a request with user data | |
2151 | * @rq: request to be unmapped | |
2152 | * @bio: bio for the request | |
2153 | * @ulen: length of user buffer | |
2154 | * | |
2155 | * Description: | |
2156 | * Unmap a request previously mapped by blk_rq_map_user(). | |
2157 | */ | |
2158 | int blk_rq_unmap_user(struct request *rq, struct bio *bio, unsigned int ulen) | |
2159 | { | |
2160 | int ret = 0; | |
2161 | ||
2162 | if (bio) { | |
2163 | if (bio_flagged(bio, BIO_USER_MAPPED)) | |
2164 | bio_unmap_user(bio); | |
2165 | else | |
2166 | ret = bio_uncopy_user(bio); | |
2167 | } | |
2168 | ||
2169 | blk_put_request(rq); | |
2170 | return ret; | |
2171 | } | |
2172 | ||
2173 | EXPORT_SYMBOL(blk_rq_unmap_user); | |
2174 | ||
2175 | /** | |
2176 | * blk_execute_rq - insert a request into queue for execution | |
2177 | * @q: queue to insert the request in | |
2178 | * @bd_disk: matching gendisk | |
2179 | * @rq: request to insert | |
2180 | * | |
2181 | * Description: | |
2182 | * Insert a fully prepared request at the back of the io scheduler queue | |
2183 | * for execution. | |
2184 | */ | |
2185 | int blk_execute_rq(request_queue_t *q, struct gendisk *bd_disk, | |
2186 | struct request *rq) | |
2187 | { | |
2188 | DECLARE_COMPLETION(wait); | |
2189 | char sense[SCSI_SENSE_BUFFERSIZE]; | |
2190 | int err = 0; | |
2191 | ||
2192 | rq->rq_disk = bd_disk; | |
2193 | ||
2194 | /* | |
2195 | * we need an extra reference to the request, so we can look at | |
2196 | * it after io completion | |
2197 | */ | |
2198 | rq->ref_count++; | |
2199 | ||
2200 | if (!rq->sense) { | |
2201 | memset(sense, 0, sizeof(sense)); | |
2202 | rq->sense = sense; | |
2203 | rq->sense_len = 0; | |
2204 | } | |
2205 | ||
2206 | rq->flags |= REQ_NOMERGE; | |
2207 | rq->waiting = &wait; | |
2208 | rq->end_io = blk_end_sync_rq; | |
2209 | elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 1); | |
2210 | generic_unplug_device(q); | |
2211 | wait_for_completion(&wait); | |
2212 | rq->waiting = NULL; | |
2213 | ||
2214 | if (rq->errors) | |
2215 | err = -EIO; | |
2216 | ||
2217 | return err; | |
2218 | } | |
2219 | ||
2220 | EXPORT_SYMBOL(blk_execute_rq); | |
2221 | ||
2222 | /** | |
2223 | * blkdev_issue_flush - queue a flush | |
2224 | * @bdev: blockdev to issue flush for | |
2225 | * @error_sector: error sector | |
2226 | * | |
2227 | * Description: | |
2228 | * Issue a flush for the block device in question. Caller can supply | |
2229 | * room for storing the error offset in case of a flush error, if they | |
2230 | * wish to. Caller must run wait_for_completion() on its own. | |
2231 | */ | |
2232 | int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector) | |
2233 | { | |
2234 | request_queue_t *q; | |
2235 | ||
2236 | if (bdev->bd_disk == NULL) | |
2237 | return -ENXIO; | |
2238 | ||
2239 | q = bdev_get_queue(bdev); | |
2240 | if (!q) | |
2241 | return -ENXIO; | |
2242 | if (!q->issue_flush_fn) | |
2243 | return -EOPNOTSUPP; | |
2244 | ||
2245 | return q->issue_flush_fn(q, bdev->bd_disk, error_sector); | |
2246 | } | |
2247 | ||
2248 | EXPORT_SYMBOL(blkdev_issue_flush); | |
2249 | ||
2250 | /** | |
2251 | * blkdev_scsi_issue_flush_fn - issue flush for SCSI devices | |
2252 | * @q: device queue | |
2253 | * @disk: gendisk | |
2254 | * @error_sector: error offset | |
2255 | * | |
2256 | * Description: | |
2257 | * Devices understanding the SCSI command set, can use this function as | |
2258 | * a helper for issuing a cache flush. Note: driver is required to store | |
2259 | * the error offset (in case of error flushing) in ->sector of struct | |
2260 | * request. | |
2261 | */ | |
2262 | int blkdev_scsi_issue_flush_fn(request_queue_t *q, struct gendisk *disk, | |
2263 | sector_t *error_sector) | |
2264 | { | |
2265 | struct request *rq = blk_get_request(q, WRITE, __GFP_WAIT); | |
2266 | int ret; | |
2267 | ||
2268 | rq->flags |= REQ_BLOCK_PC | REQ_SOFTBARRIER; | |
2269 | rq->sector = 0; | |
2270 | memset(rq->cmd, 0, sizeof(rq->cmd)); | |
2271 | rq->cmd[0] = 0x35; | |
2272 | rq->cmd_len = 12; | |
2273 | rq->data = NULL; | |
2274 | rq->data_len = 0; | |
2275 | rq->timeout = 60 * HZ; | |
2276 | ||
2277 | ret = blk_execute_rq(q, disk, rq); | |
2278 | ||
2279 | if (ret && error_sector) | |
2280 | *error_sector = rq->sector; | |
2281 | ||
2282 | blk_put_request(rq); | |
2283 | return ret; | |
2284 | } | |
2285 | ||
2286 | EXPORT_SYMBOL(blkdev_scsi_issue_flush_fn); | |
2287 | ||
2288 | void drive_stat_acct(struct request *rq, int nr_sectors, int new_io) | |
2289 | { | |
2290 | int rw = rq_data_dir(rq); | |
2291 | ||
2292 | if (!blk_fs_request(rq) || !rq->rq_disk) | |
2293 | return; | |
2294 | ||
2295 | if (rw == READ) { | |
2296 | __disk_stat_add(rq->rq_disk, read_sectors, nr_sectors); | |
2297 | if (!new_io) | |
2298 | __disk_stat_inc(rq->rq_disk, read_merges); | |
2299 | } else if (rw == WRITE) { | |
2300 | __disk_stat_add(rq->rq_disk, write_sectors, nr_sectors); | |
2301 | if (!new_io) | |
2302 | __disk_stat_inc(rq->rq_disk, write_merges); | |
2303 | } | |
2304 | if (new_io) { | |
2305 | disk_round_stats(rq->rq_disk); | |
2306 | rq->rq_disk->in_flight++; | |
2307 | } | |
2308 | } | |
2309 | ||
2310 | /* | |
2311 | * add-request adds a request to the linked list. | |
2312 | * queue lock is held and interrupts disabled, as we muck with the | |
2313 | * request queue list. | |
2314 | */ | |
2315 | static inline void add_request(request_queue_t * q, struct request * req) | |
2316 | { | |
2317 | drive_stat_acct(req, req->nr_sectors, 1); | |
2318 | ||
2319 | if (q->activity_fn) | |
2320 | q->activity_fn(q->activity_data, rq_data_dir(req)); | |
2321 | ||
2322 | /* | |
2323 | * elevator indicated where it wants this request to be | |
2324 | * inserted at elevator_merge time | |
2325 | */ | |
2326 | __elv_add_request(q, req, ELEVATOR_INSERT_SORT, 0); | |
2327 | } | |
2328 | ||
2329 | /* | |
2330 | * disk_round_stats() - Round off the performance stats on a struct | |
2331 | * disk_stats. | |
2332 | * | |
2333 | * The average IO queue length and utilisation statistics are maintained | |
2334 | * by observing the current state of the queue length and the amount of | |
2335 | * time it has been in this state for. | |
2336 | * | |
2337 | * Normally, that accounting is done on IO completion, but that can result | |
2338 | * in more than a second's worth of IO being accounted for within any one | |
2339 | * second, leading to >100% utilisation. To deal with that, we call this | |
2340 | * function to do a round-off before returning the results when reading | |
2341 | * /proc/diskstats. This accounts immediately for all queue usage up to | |
2342 | * the current jiffies and restarts the counters again. | |
2343 | */ | |
2344 | void disk_round_stats(struct gendisk *disk) | |
2345 | { | |
2346 | unsigned long now = jiffies; | |
2347 | ||
2348 | __disk_stat_add(disk, time_in_queue, | |
2349 | disk->in_flight * (now - disk->stamp)); | |
2350 | disk->stamp = now; | |
2351 | ||
2352 | if (disk->in_flight) | |
2353 | __disk_stat_add(disk, io_ticks, (now - disk->stamp_idle)); | |
2354 | disk->stamp_idle = now; | |
2355 | } | |
2356 | ||
2357 | /* | |
2358 | * queue lock must be held | |
2359 | */ | |
2360 | static void __blk_put_request(request_queue_t *q, struct request *req) | |
2361 | { | |
2362 | struct request_list *rl = req->rl; | |
2363 | ||
2364 | if (unlikely(!q)) | |
2365 | return; | |
2366 | if (unlikely(--req->ref_count)) | |
2367 | return; | |
2368 | ||
2369 | req->rq_status = RQ_INACTIVE; | |
2370 | req->q = NULL; | |
2371 | req->rl = NULL; | |
2372 | ||
2373 | /* | |
2374 | * Request may not have originated from ll_rw_blk. if not, | |
2375 | * it didn't come out of our reserved rq pools | |
2376 | */ | |
2377 | if (rl) { | |
2378 | int rw = rq_data_dir(req); | |
2379 | ||
2380 | elv_completed_request(q, req); | |
2381 | ||
2382 | BUG_ON(!list_empty(&req->queuelist)); | |
2383 | ||
2384 | blk_free_request(q, req); | |
2385 | freed_request(q, rw); | |
2386 | } | |
2387 | } | |
2388 | ||
2389 | void blk_put_request(struct request *req) | |
2390 | { | |
2391 | /* | |
2392 | * if req->rl isn't set, this request didnt originate from the | |
2393 | * block layer, so it's safe to just disregard it | |
2394 | */ | |
2395 | if (req->rl) { | |
2396 | unsigned long flags; | |
2397 | request_queue_t *q = req->q; | |
2398 | ||
2399 | spin_lock_irqsave(q->queue_lock, flags); | |
2400 | __blk_put_request(q, req); | |
2401 | spin_unlock_irqrestore(q->queue_lock, flags); | |
2402 | } | |
2403 | } | |
2404 | ||
2405 | EXPORT_SYMBOL(blk_put_request); | |
2406 | ||
2407 | /** | |
2408 | * blk_end_sync_rq - executes a completion event on a request | |
2409 | * @rq: request to complete | |
2410 | */ | |
2411 | void blk_end_sync_rq(struct request *rq) | |
2412 | { | |
2413 | struct completion *waiting = rq->waiting; | |
2414 | ||
2415 | rq->waiting = NULL; | |
2416 | __blk_put_request(rq->q, rq); | |
2417 | ||
2418 | /* | |
2419 | * complete last, if this is a stack request the process (and thus | |
2420 | * the rq pointer) could be invalid right after this complete() | |
2421 | */ | |
2422 | complete(waiting); | |
2423 | } | |
2424 | EXPORT_SYMBOL(blk_end_sync_rq); | |
2425 | ||
2426 | /** | |
2427 | * blk_congestion_wait - wait for a queue to become uncongested | |
2428 | * @rw: READ or WRITE | |
2429 | * @timeout: timeout in jiffies | |
2430 | * | |
2431 | * Waits for up to @timeout jiffies for a queue (any queue) to exit congestion. | |
2432 | * If no queues are congested then just wait for the next request to be | |
2433 | * returned. | |
2434 | */ | |
2435 | long blk_congestion_wait(int rw, long timeout) | |
2436 | { | |
2437 | long ret; | |
2438 | DEFINE_WAIT(wait); | |
2439 | wait_queue_head_t *wqh = &congestion_wqh[rw]; | |
2440 | ||
2441 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
2442 | ret = io_schedule_timeout(timeout); | |
2443 | finish_wait(wqh, &wait); | |
2444 | return ret; | |
2445 | } | |
2446 | ||
2447 | EXPORT_SYMBOL(blk_congestion_wait); | |
2448 | ||
2449 | /* | |
2450 | * Has to be called with the request spinlock acquired | |
2451 | */ | |
2452 | static int attempt_merge(request_queue_t *q, struct request *req, | |
2453 | struct request *next) | |
2454 | { | |
2455 | if (!rq_mergeable(req) || !rq_mergeable(next)) | |
2456 | return 0; | |
2457 | ||
2458 | /* | |
2459 | * not contigious | |
2460 | */ | |
2461 | if (req->sector + req->nr_sectors != next->sector) | |
2462 | return 0; | |
2463 | ||
2464 | if (rq_data_dir(req) != rq_data_dir(next) | |
2465 | || req->rq_disk != next->rq_disk | |
2466 | || next->waiting || next->special) | |
2467 | return 0; | |
2468 | ||
2469 | /* | |
2470 | * If we are allowed to merge, then append bio list | |
2471 | * from next to rq and release next. merge_requests_fn | |
2472 | * will have updated segment counts, update sector | |
2473 | * counts here. | |
2474 | */ | |
2475 | if (!q->merge_requests_fn(q, req, next)) | |
2476 | return 0; | |
2477 | ||
2478 | /* | |
2479 | * At this point we have either done a back merge | |
2480 | * or front merge. We need the smaller start_time of | |
2481 | * the merged requests to be the current request | |
2482 | * for accounting purposes. | |
2483 | */ | |
2484 | if (time_after(req->start_time, next->start_time)) | |
2485 | req->start_time = next->start_time; | |
2486 | ||
2487 | req->biotail->bi_next = next->bio; | |
2488 | req->biotail = next->biotail; | |
2489 | ||
2490 | req->nr_sectors = req->hard_nr_sectors += next->hard_nr_sectors; | |
2491 | ||
2492 | elv_merge_requests(q, req, next); | |
2493 | ||
2494 | if (req->rq_disk) { | |
2495 | disk_round_stats(req->rq_disk); | |
2496 | req->rq_disk->in_flight--; | |
2497 | } | |
2498 | ||
2499 | __blk_put_request(q, next); | |
2500 | return 1; | |
2501 | } | |
2502 | ||
2503 | static inline int attempt_back_merge(request_queue_t *q, struct request *rq) | |
2504 | { | |
2505 | struct request *next = elv_latter_request(q, rq); | |
2506 | ||
2507 | if (next) | |
2508 | return attempt_merge(q, rq, next); | |
2509 | ||
2510 | return 0; | |
2511 | } | |
2512 | ||
2513 | static inline int attempt_front_merge(request_queue_t *q, struct request *rq) | |
2514 | { | |
2515 | struct request *prev = elv_former_request(q, rq); | |
2516 | ||
2517 | if (prev) | |
2518 | return attempt_merge(q, prev, rq); | |
2519 | ||
2520 | return 0; | |
2521 | } | |
2522 | ||
2523 | /** | |
2524 | * blk_attempt_remerge - attempt to remerge active head with next request | |
2525 | * @q: The &request_queue_t belonging to the device | |
2526 | * @rq: The head request (usually) | |
2527 | * | |
2528 | * Description: | |
2529 | * For head-active devices, the queue can easily be unplugged so quickly | |
2530 | * that proper merging is not done on the front request. This may hurt | |
2531 | * performance greatly for some devices. The block layer cannot safely | |
2532 | * do merging on that first request for these queues, but the driver can | |
2533 | * call this function and make it happen any way. Only the driver knows | |
2534 | * when it is safe to do so. | |
2535 | **/ | |
2536 | void blk_attempt_remerge(request_queue_t *q, struct request *rq) | |
2537 | { | |
2538 | unsigned long flags; | |
2539 | ||
2540 | spin_lock_irqsave(q->queue_lock, flags); | |
2541 | attempt_back_merge(q, rq); | |
2542 | spin_unlock_irqrestore(q->queue_lock, flags); | |
2543 | } | |
2544 | ||
2545 | EXPORT_SYMBOL(blk_attempt_remerge); | |
2546 | ||
2547 | /* | |
2548 | * Non-locking blk_attempt_remerge variant. | |
2549 | */ | |
2550 | void __blk_attempt_remerge(request_queue_t *q, struct request *rq) | |
2551 | { | |
2552 | attempt_back_merge(q, rq); | |
2553 | } | |
2554 | ||
2555 | EXPORT_SYMBOL(__blk_attempt_remerge); | |
2556 | ||
2557 | static int __make_request(request_queue_t *q, struct bio *bio) | |
2558 | { | |
2559 | struct request *req, *freereq = NULL; | |
4a534f93 | 2560 | int el_ret, rw, nr_sectors, cur_nr_sectors, barrier, err, sync; |
1da177e4 LT |
2561 | sector_t sector; |
2562 | ||
2563 | sector = bio->bi_sector; | |
2564 | nr_sectors = bio_sectors(bio); | |
2565 | cur_nr_sectors = bio_cur_sectors(bio); | |
2566 | ||
2567 | rw = bio_data_dir(bio); | |
4a534f93 | 2568 | sync = bio_sync(bio); |
1da177e4 LT |
2569 | |
2570 | /* | |
2571 | * low level driver can indicate that it wants pages above a | |
2572 | * certain limit bounced to low memory (ie for highmem, or even | |
2573 | * ISA dma in theory) | |
2574 | */ | |
2575 | blk_queue_bounce(q, &bio); | |
2576 | ||
2577 | spin_lock_prefetch(q->queue_lock); | |
2578 | ||
2579 | barrier = bio_barrier(bio); | |
2580 | if (barrier && (q->ordered == QUEUE_ORDERED_NONE)) { | |
2581 | err = -EOPNOTSUPP; | |
2582 | goto end_io; | |
2583 | } | |
2584 | ||
2585 | again: | |
2586 | spin_lock_irq(q->queue_lock); | |
2587 | ||
2588 | if (elv_queue_empty(q)) { | |
2589 | blk_plug_device(q); | |
2590 | goto get_rq; | |
2591 | } | |
2592 | if (barrier) | |
2593 | goto get_rq; | |
2594 | ||
2595 | el_ret = elv_merge(q, &req, bio); | |
2596 | switch (el_ret) { | |
2597 | case ELEVATOR_BACK_MERGE: | |
2598 | BUG_ON(!rq_mergeable(req)); | |
2599 | ||
2600 | if (!q->back_merge_fn(q, req, bio)) | |
2601 | break; | |
2602 | ||
2603 | req->biotail->bi_next = bio; | |
2604 | req->biotail = bio; | |
2605 | req->nr_sectors = req->hard_nr_sectors += nr_sectors; | |
2606 | drive_stat_acct(req, nr_sectors, 0); | |
2607 | if (!attempt_back_merge(q, req)) | |
2608 | elv_merged_request(q, req); | |
2609 | goto out; | |
2610 | ||
2611 | case ELEVATOR_FRONT_MERGE: | |
2612 | BUG_ON(!rq_mergeable(req)); | |
2613 | ||
2614 | if (!q->front_merge_fn(q, req, bio)) | |
2615 | break; | |
2616 | ||
2617 | bio->bi_next = req->bio; | |
2618 | req->bio = bio; | |
2619 | ||
2620 | /* | |
2621 | * may not be valid. if the low level driver said | |
2622 | * it didn't need a bounce buffer then it better | |
2623 | * not touch req->buffer either... | |
2624 | */ | |
2625 | req->buffer = bio_data(bio); | |
2626 | req->current_nr_sectors = cur_nr_sectors; | |
2627 | req->hard_cur_sectors = cur_nr_sectors; | |
2628 | req->sector = req->hard_sector = sector; | |
2629 | req->nr_sectors = req->hard_nr_sectors += nr_sectors; | |
2630 | drive_stat_acct(req, nr_sectors, 0); | |
2631 | if (!attempt_front_merge(q, req)) | |
2632 | elv_merged_request(q, req); | |
2633 | goto out; | |
2634 | ||
2635 | /* | |
2636 | * elevator says don't/can't merge. get new request | |
2637 | */ | |
2638 | case ELEVATOR_NO_MERGE: | |
2639 | break; | |
2640 | ||
2641 | default: | |
2642 | printk("elevator returned crap (%d)\n", el_ret); | |
2643 | BUG(); | |
2644 | } | |
2645 | ||
2646 | /* | |
2647 | * Grab a free request from the freelist - if that is empty, check | |
2648 | * if we are doing read ahead and abort instead of blocking for | |
2649 | * a free slot. | |
2650 | */ | |
2651 | get_rq: | |
2652 | if (freereq) { | |
2653 | req = freereq; | |
2654 | freereq = NULL; | |
2655 | } else { | |
2656 | spin_unlock_irq(q->queue_lock); | |
2657 | if ((freereq = get_request(q, rw, GFP_ATOMIC)) == NULL) { | |
2658 | /* | |
2659 | * READA bit set | |
2660 | */ | |
2661 | err = -EWOULDBLOCK; | |
2662 | if (bio_rw_ahead(bio)) | |
2663 | goto end_io; | |
2664 | ||
2665 | freereq = get_request_wait(q, rw); | |
2666 | } | |
2667 | goto again; | |
2668 | } | |
2669 | ||
2670 | req->flags |= REQ_CMD; | |
2671 | ||
2672 | /* | |
2673 | * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST) | |
2674 | */ | |
2675 | if (bio_rw_ahead(bio) || bio_failfast(bio)) | |
2676 | req->flags |= REQ_FAILFAST; | |
2677 | ||
2678 | /* | |
2679 | * REQ_BARRIER implies no merging, but lets make it explicit | |
2680 | */ | |
2681 | if (barrier) | |
2682 | req->flags |= (REQ_HARDBARRIER | REQ_NOMERGE); | |
2683 | ||
2684 | req->errors = 0; | |
2685 | req->hard_sector = req->sector = sector; | |
2686 | req->hard_nr_sectors = req->nr_sectors = nr_sectors; | |
2687 | req->current_nr_sectors = req->hard_cur_sectors = cur_nr_sectors; | |
2688 | req->nr_phys_segments = bio_phys_segments(q, bio); | |
2689 | req->nr_hw_segments = bio_hw_segments(q, bio); | |
2690 | req->buffer = bio_data(bio); /* see ->buffer comment above */ | |
2691 | req->waiting = NULL; | |
2692 | req->bio = req->biotail = bio; | |
2693 | req->rq_disk = bio->bi_bdev->bd_disk; | |
2694 | req->start_time = jiffies; | |
2695 | ||
2696 | add_request(q, req); | |
2697 | out: | |
2698 | if (freereq) | |
2699 | __blk_put_request(q, freereq); | |
4a534f93 | 2700 | if (sync) |
1da177e4 LT |
2701 | __generic_unplug_device(q); |
2702 | ||
2703 | spin_unlock_irq(q->queue_lock); | |
2704 | return 0; | |
2705 | ||
2706 | end_io: | |
2707 | bio_endio(bio, nr_sectors << 9, err); | |
2708 | return 0; | |
2709 | } | |
2710 | ||
2711 | /* | |
2712 | * If bio->bi_dev is a partition, remap the location | |
2713 | */ | |
2714 | static inline void blk_partition_remap(struct bio *bio) | |
2715 | { | |
2716 | struct block_device *bdev = bio->bi_bdev; | |
2717 | ||
2718 | if (bdev != bdev->bd_contains) { | |
2719 | struct hd_struct *p = bdev->bd_part; | |
2720 | ||
2721 | switch (bio->bi_rw) { | |
2722 | case READ: | |
2723 | p->read_sectors += bio_sectors(bio); | |
2724 | p->reads++; | |
2725 | break; | |
2726 | case WRITE: | |
2727 | p->write_sectors += bio_sectors(bio); | |
2728 | p->writes++; | |
2729 | break; | |
2730 | } | |
2731 | bio->bi_sector += p->start_sect; | |
2732 | bio->bi_bdev = bdev->bd_contains; | |
2733 | } | |
2734 | } | |
2735 | ||
2736 | void blk_finish_queue_drain(request_queue_t *q) | |
2737 | { | |
2738 | struct request_list *rl = &q->rq; | |
2739 | struct request *rq; | |
2740 | ||
2741 | spin_lock_irq(q->queue_lock); | |
2742 | clear_bit(QUEUE_FLAG_DRAIN, &q->queue_flags); | |
2743 | ||
2744 | while (!list_empty(&q->drain_list)) { | |
2745 | rq = list_entry_rq(q->drain_list.next); | |
2746 | ||
2747 | list_del_init(&rq->queuelist); | |
2748 | __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 1); | |
2749 | } | |
2750 | ||
2751 | spin_unlock_irq(q->queue_lock); | |
2752 | ||
2753 | wake_up(&rl->wait[0]); | |
2754 | wake_up(&rl->wait[1]); | |
2755 | wake_up(&rl->drain); | |
2756 | } | |
2757 | ||
2758 | static int wait_drain(request_queue_t *q, struct request_list *rl, int dispatch) | |
2759 | { | |
2760 | int wait = rl->count[READ] + rl->count[WRITE]; | |
2761 | ||
2762 | if (dispatch) | |
2763 | wait += !list_empty(&q->queue_head); | |
2764 | ||
2765 | return wait; | |
2766 | } | |
2767 | ||
2768 | /* | |
2769 | * We rely on the fact that only requests allocated through blk_alloc_request() | |
2770 | * have io scheduler private data structures associated with them. Any other | |
2771 | * type of request (allocated on stack or through kmalloc()) should not go | |
2772 | * to the io scheduler core, but be attached to the queue head instead. | |
2773 | */ | |
2774 | void blk_wait_queue_drained(request_queue_t *q, int wait_dispatch) | |
2775 | { | |
2776 | struct request_list *rl = &q->rq; | |
2777 | DEFINE_WAIT(wait); | |
2778 | ||
2779 | spin_lock_irq(q->queue_lock); | |
2780 | set_bit(QUEUE_FLAG_DRAIN, &q->queue_flags); | |
2781 | ||
2782 | while (wait_drain(q, rl, wait_dispatch)) { | |
2783 | prepare_to_wait(&rl->drain, &wait, TASK_UNINTERRUPTIBLE); | |
2784 | ||
2785 | if (wait_drain(q, rl, wait_dispatch)) { | |
2786 | __generic_unplug_device(q); | |
2787 | spin_unlock_irq(q->queue_lock); | |
2788 | io_schedule(); | |
2789 | spin_lock_irq(q->queue_lock); | |
2790 | } | |
2791 | ||
2792 | finish_wait(&rl->drain, &wait); | |
2793 | } | |
2794 | ||
2795 | spin_unlock_irq(q->queue_lock); | |
2796 | } | |
2797 | ||
2798 | /* | |
2799 | * block waiting for the io scheduler being started again. | |
2800 | */ | |
2801 | static inline void block_wait_queue_running(request_queue_t *q) | |
2802 | { | |
2803 | DEFINE_WAIT(wait); | |
2804 | ||
2805 | while (test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags)) { | |
2806 | struct request_list *rl = &q->rq; | |
2807 | ||
2808 | prepare_to_wait_exclusive(&rl->drain, &wait, | |
2809 | TASK_UNINTERRUPTIBLE); | |
2810 | ||
2811 | /* | |
2812 | * re-check the condition. avoids using prepare_to_wait() | |
2813 | * in the fast path (queue is running) | |
2814 | */ | |
2815 | if (test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags)) | |
2816 | io_schedule(); | |
2817 | ||
2818 | finish_wait(&rl->drain, &wait); | |
2819 | } | |
2820 | } | |
2821 | ||
2822 | static void handle_bad_sector(struct bio *bio) | |
2823 | { | |
2824 | char b[BDEVNAME_SIZE]; | |
2825 | ||
2826 | printk(KERN_INFO "attempt to access beyond end of device\n"); | |
2827 | printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n", | |
2828 | bdevname(bio->bi_bdev, b), | |
2829 | bio->bi_rw, | |
2830 | (unsigned long long)bio->bi_sector + bio_sectors(bio), | |
2831 | (long long)(bio->bi_bdev->bd_inode->i_size >> 9)); | |
2832 | ||
2833 | set_bit(BIO_EOF, &bio->bi_flags); | |
2834 | } | |
2835 | ||
2836 | /** | |
2837 | * generic_make_request: hand a buffer to its device driver for I/O | |
2838 | * @bio: The bio describing the location in memory and on the device. | |
2839 | * | |
2840 | * generic_make_request() is used to make I/O requests of block | |
2841 | * devices. It is passed a &struct bio, which describes the I/O that needs | |
2842 | * to be done. | |
2843 | * | |
2844 | * generic_make_request() does not return any status. The | |
2845 | * success/failure status of the request, along with notification of | |
2846 | * completion, is delivered asynchronously through the bio->bi_end_io | |
2847 | * function described (one day) else where. | |
2848 | * | |
2849 | * The caller of generic_make_request must make sure that bi_io_vec | |
2850 | * are set to describe the memory buffer, and that bi_dev and bi_sector are | |
2851 | * set to describe the device address, and the | |
2852 | * bi_end_io and optionally bi_private are set to describe how | |
2853 | * completion notification should be signaled. | |
2854 | * | |
2855 | * generic_make_request and the drivers it calls may use bi_next if this | |
2856 | * bio happens to be merged with someone else, and may change bi_dev and | |
2857 | * bi_sector for remaps as it sees fit. So the values of these fields | |
2858 | * should NOT be depended on after the call to generic_make_request. | |
2859 | */ | |
2860 | void generic_make_request(struct bio *bio) | |
2861 | { | |
2862 | request_queue_t *q; | |
2863 | sector_t maxsector; | |
2864 | int ret, nr_sectors = bio_sectors(bio); | |
2865 | ||
2866 | might_sleep(); | |
2867 | /* Test device or partition size, when known. */ | |
2868 | maxsector = bio->bi_bdev->bd_inode->i_size >> 9; | |
2869 | if (maxsector) { | |
2870 | sector_t sector = bio->bi_sector; | |
2871 | ||
2872 | if (maxsector < nr_sectors || maxsector - nr_sectors < sector) { | |
2873 | /* | |
2874 | * This may well happen - the kernel calls bread() | |
2875 | * without checking the size of the device, e.g., when | |
2876 | * mounting a device. | |
2877 | */ | |
2878 | handle_bad_sector(bio); | |
2879 | goto end_io; | |
2880 | } | |
2881 | } | |
2882 | ||
2883 | /* | |
2884 | * Resolve the mapping until finished. (drivers are | |
2885 | * still free to implement/resolve their own stacking | |
2886 | * by explicitly returning 0) | |
2887 | * | |
2888 | * NOTE: we don't repeat the blk_size check for each new device. | |
2889 | * Stacking drivers are expected to know what they are doing. | |
2890 | */ | |
2891 | do { | |
2892 | char b[BDEVNAME_SIZE]; | |
2893 | ||
2894 | q = bdev_get_queue(bio->bi_bdev); | |
2895 | if (!q) { | |
2896 | printk(KERN_ERR | |
2897 | "generic_make_request: Trying to access " | |
2898 | "nonexistent block-device %s (%Lu)\n", | |
2899 | bdevname(bio->bi_bdev, b), | |
2900 | (long long) bio->bi_sector); | |
2901 | end_io: | |
2902 | bio_endio(bio, bio->bi_size, -EIO); | |
2903 | break; | |
2904 | } | |
2905 | ||
2906 | if (unlikely(bio_sectors(bio) > q->max_hw_sectors)) { | |
2907 | printk("bio too big device %s (%u > %u)\n", | |
2908 | bdevname(bio->bi_bdev, b), | |
2909 | bio_sectors(bio), | |
2910 | q->max_hw_sectors); | |
2911 | goto end_io; | |
2912 | } | |
2913 | ||
2914 | if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) | |
2915 | goto end_io; | |
2916 | ||
2917 | block_wait_queue_running(q); | |
2918 | ||
2919 | /* | |
2920 | * If this device has partitions, remap block n | |
2921 | * of partition p to block n+start(p) of the disk. | |
2922 | */ | |
2923 | blk_partition_remap(bio); | |
2924 | ||
2925 | ret = q->make_request_fn(q, bio); | |
2926 | } while (ret); | |
2927 | } | |
2928 | ||
2929 | EXPORT_SYMBOL(generic_make_request); | |
2930 | ||
2931 | /** | |
2932 | * submit_bio: submit a bio to the block device layer for I/O | |
2933 | * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead) | |
2934 | * @bio: The &struct bio which describes the I/O | |
2935 | * | |
2936 | * submit_bio() is very similar in purpose to generic_make_request(), and | |
2937 | * uses that function to do most of the work. Both are fairly rough | |
2938 | * interfaces, @bio must be presetup and ready for I/O. | |
2939 | * | |
2940 | */ | |
2941 | void submit_bio(int rw, struct bio *bio) | |
2942 | { | |
2943 | int count = bio_sectors(bio); | |
2944 | ||
2945 | BIO_BUG_ON(!bio->bi_size); | |
2946 | BIO_BUG_ON(!bio->bi_io_vec); | |
2947 | bio->bi_rw = rw; | |
2948 | if (rw & WRITE) | |
2949 | mod_page_state(pgpgout, count); | |
2950 | else | |
2951 | mod_page_state(pgpgin, count); | |
2952 | ||
2953 | if (unlikely(block_dump)) { | |
2954 | char b[BDEVNAME_SIZE]; | |
2955 | printk(KERN_DEBUG "%s(%d): %s block %Lu on %s\n", | |
2956 | current->comm, current->pid, | |
2957 | (rw & WRITE) ? "WRITE" : "READ", | |
2958 | (unsigned long long)bio->bi_sector, | |
2959 | bdevname(bio->bi_bdev,b)); | |
2960 | } | |
2961 | ||
2962 | generic_make_request(bio); | |
2963 | } | |
2964 | ||
2965 | EXPORT_SYMBOL(submit_bio); | |
2966 | ||
2967 | void blk_recalc_rq_segments(struct request *rq) | |
2968 | { | |
2969 | struct bio *bio, *prevbio = NULL; | |
2970 | int nr_phys_segs, nr_hw_segs; | |
2971 | unsigned int phys_size, hw_size; | |
2972 | request_queue_t *q = rq->q; | |
2973 | ||
2974 | if (!rq->bio) | |
2975 | return; | |
2976 | ||
2977 | phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0; | |
2978 | rq_for_each_bio(bio, rq) { | |
2979 | /* Force bio hw/phys segs to be recalculated. */ | |
2980 | bio->bi_flags &= ~(1 << BIO_SEG_VALID); | |
2981 | ||
2982 | nr_phys_segs += bio_phys_segments(q, bio); | |
2983 | nr_hw_segs += bio_hw_segments(q, bio); | |
2984 | if (prevbio) { | |
2985 | int pseg = phys_size + prevbio->bi_size + bio->bi_size; | |
2986 | int hseg = hw_size + prevbio->bi_size + bio->bi_size; | |
2987 | ||
2988 | if (blk_phys_contig_segment(q, prevbio, bio) && | |
2989 | pseg <= q->max_segment_size) { | |
2990 | nr_phys_segs--; | |
2991 | phys_size += prevbio->bi_size + bio->bi_size; | |
2992 | } else | |
2993 | phys_size = 0; | |
2994 | ||
2995 | if (blk_hw_contig_segment(q, prevbio, bio) && | |
2996 | hseg <= q->max_segment_size) { | |
2997 | nr_hw_segs--; | |
2998 | hw_size += prevbio->bi_size + bio->bi_size; | |
2999 | } else | |
3000 | hw_size = 0; | |
3001 | } | |
3002 | prevbio = bio; | |
3003 | } | |
3004 | ||
3005 | rq->nr_phys_segments = nr_phys_segs; | |
3006 | rq->nr_hw_segments = nr_hw_segs; | |
3007 | } | |
3008 | ||
3009 | void blk_recalc_rq_sectors(struct request *rq, int nsect) | |
3010 | { | |
3011 | if (blk_fs_request(rq)) { | |
3012 | rq->hard_sector += nsect; | |
3013 | rq->hard_nr_sectors -= nsect; | |
3014 | ||
3015 | /* | |
3016 | * Move the I/O submission pointers ahead if required. | |
3017 | */ | |
3018 | if ((rq->nr_sectors >= rq->hard_nr_sectors) && | |
3019 | (rq->sector <= rq->hard_sector)) { | |
3020 | rq->sector = rq->hard_sector; | |
3021 | rq->nr_sectors = rq->hard_nr_sectors; | |
3022 | rq->hard_cur_sectors = bio_cur_sectors(rq->bio); | |
3023 | rq->current_nr_sectors = rq->hard_cur_sectors; | |
3024 | rq->buffer = bio_data(rq->bio); | |
3025 | } | |
3026 | ||
3027 | /* | |
3028 | * if total number of sectors is less than the first segment | |
3029 | * size, something has gone terribly wrong | |
3030 | */ | |
3031 | if (rq->nr_sectors < rq->current_nr_sectors) { | |
3032 | printk("blk: request botched\n"); | |
3033 | rq->nr_sectors = rq->current_nr_sectors; | |
3034 | } | |
3035 | } | |
3036 | } | |
3037 | ||
3038 | static int __end_that_request_first(struct request *req, int uptodate, | |
3039 | int nr_bytes) | |
3040 | { | |
3041 | int total_bytes, bio_nbytes, error, next_idx = 0; | |
3042 | struct bio *bio; | |
3043 | ||
3044 | /* | |
3045 | * extend uptodate bool to allow < 0 value to be direct io error | |
3046 | */ | |
3047 | error = 0; | |
3048 | if (end_io_error(uptodate)) | |
3049 | error = !uptodate ? -EIO : uptodate; | |
3050 | ||
3051 | /* | |
3052 | * for a REQ_BLOCK_PC request, we want to carry any eventual | |
3053 | * sense key with us all the way through | |
3054 | */ | |
3055 | if (!blk_pc_request(req)) | |
3056 | req->errors = 0; | |
3057 | ||
3058 | if (!uptodate) { | |
3059 | if (blk_fs_request(req) && !(req->flags & REQ_QUIET)) | |
3060 | printk("end_request: I/O error, dev %s, sector %llu\n", | |
3061 | req->rq_disk ? req->rq_disk->disk_name : "?", | |
3062 | (unsigned long long)req->sector); | |
3063 | } | |
3064 | ||
3065 | total_bytes = bio_nbytes = 0; | |
3066 | while ((bio = req->bio) != NULL) { | |
3067 | int nbytes; | |
3068 | ||
3069 | if (nr_bytes >= bio->bi_size) { | |
3070 | req->bio = bio->bi_next; | |
3071 | nbytes = bio->bi_size; | |
3072 | bio_endio(bio, nbytes, error); | |
3073 | next_idx = 0; | |
3074 | bio_nbytes = 0; | |
3075 | } else { | |
3076 | int idx = bio->bi_idx + next_idx; | |
3077 | ||
3078 | if (unlikely(bio->bi_idx >= bio->bi_vcnt)) { | |
3079 | blk_dump_rq_flags(req, "__end_that"); | |
3080 | printk("%s: bio idx %d >= vcnt %d\n", | |
3081 | __FUNCTION__, | |
3082 | bio->bi_idx, bio->bi_vcnt); | |
3083 | break; | |
3084 | } | |
3085 | ||
3086 | nbytes = bio_iovec_idx(bio, idx)->bv_len; | |
3087 | BIO_BUG_ON(nbytes > bio->bi_size); | |
3088 | ||
3089 | /* | |
3090 | * not a complete bvec done | |
3091 | */ | |
3092 | if (unlikely(nbytes > nr_bytes)) { | |
3093 | bio_nbytes += nr_bytes; | |
3094 | total_bytes += nr_bytes; | |
3095 | break; | |
3096 | } | |
3097 | ||
3098 | /* | |
3099 | * advance to the next vector | |
3100 | */ | |
3101 | next_idx++; | |
3102 | bio_nbytes += nbytes; | |
3103 | } | |
3104 | ||
3105 | total_bytes += nbytes; | |
3106 | nr_bytes -= nbytes; | |
3107 | ||
3108 | if ((bio = req->bio)) { | |
3109 | /* | |
3110 | * end more in this run, or just return 'not-done' | |
3111 | */ | |
3112 | if (unlikely(nr_bytes <= 0)) | |
3113 | break; | |
3114 | } | |
3115 | } | |
3116 | ||
3117 | /* | |
3118 | * completely done | |
3119 | */ | |
3120 | if (!req->bio) | |
3121 | return 0; | |
3122 | ||
3123 | /* | |
3124 | * if the request wasn't completed, update state | |
3125 | */ | |
3126 | if (bio_nbytes) { | |
3127 | bio_endio(bio, bio_nbytes, error); | |
3128 | bio->bi_idx += next_idx; | |
3129 | bio_iovec(bio)->bv_offset += nr_bytes; | |
3130 | bio_iovec(bio)->bv_len -= nr_bytes; | |
3131 | } | |
3132 | ||
3133 | blk_recalc_rq_sectors(req, total_bytes >> 9); | |
3134 | blk_recalc_rq_segments(req); | |
3135 | return 1; | |
3136 | } | |
3137 | ||
3138 | /** | |
3139 | * end_that_request_first - end I/O on a request | |
3140 | * @req: the request being processed | |
3141 | * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error | |
3142 | * @nr_sectors: number of sectors to end I/O on | |
3143 | * | |
3144 | * Description: | |
3145 | * Ends I/O on a number of sectors attached to @req, and sets it up | |
3146 | * for the next range of segments (if any) in the cluster. | |
3147 | * | |
3148 | * Return: | |
3149 | * 0 - we are done with this request, call end_that_request_last() | |
3150 | * 1 - still buffers pending for this request | |
3151 | **/ | |
3152 | int end_that_request_first(struct request *req, int uptodate, int nr_sectors) | |
3153 | { | |
3154 | return __end_that_request_first(req, uptodate, nr_sectors << 9); | |
3155 | } | |
3156 | ||
3157 | EXPORT_SYMBOL(end_that_request_first); | |
3158 | ||
3159 | /** | |
3160 | * end_that_request_chunk - end I/O on a request | |
3161 | * @req: the request being processed | |
3162 | * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error | |
3163 | * @nr_bytes: number of bytes to complete | |
3164 | * | |
3165 | * Description: | |
3166 | * Ends I/O on a number of bytes attached to @req, and sets it up | |
3167 | * for the next range of segments (if any). Like end_that_request_first(), | |
3168 | * but deals with bytes instead of sectors. | |
3169 | * | |
3170 | * Return: | |
3171 | * 0 - we are done with this request, call end_that_request_last() | |
3172 | * 1 - still buffers pending for this request | |
3173 | **/ | |
3174 | int end_that_request_chunk(struct request *req, int uptodate, int nr_bytes) | |
3175 | { | |
3176 | return __end_that_request_first(req, uptodate, nr_bytes); | |
3177 | } | |
3178 | ||
3179 | EXPORT_SYMBOL(end_that_request_chunk); | |
3180 | ||
3181 | /* | |
3182 | * queue lock must be held | |
3183 | */ | |
3184 | void end_that_request_last(struct request *req) | |
3185 | { | |
3186 | struct gendisk *disk = req->rq_disk; | |
3187 | ||
3188 | if (unlikely(laptop_mode) && blk_fs_request(req)) | |
3189 | laptop_io_completion(); | |
3190 | ||
3191 | if (disk && blk_fs_request(req)) { | |
3192 | unsigned long duration = jiffies - req->start_time; | |
3193 | switch (rq_data_dir(req)) { | |
3194 | case WRITE: | |
3195 | __disk_stat_inc(disk, writes); | |
3196 | __disk_stat_add(disk, write_ticks, duration); | |
3197 | break; | |
3198 | case READ: | |
3199 | __disk_stat_inc(disk, reads); | |
3200 | __disk_stat_add(disk, read_ticks, duration); | |
3201 | break; | |
3202 | } | |
3203 | disk_round_stats(disk); | |
3204 | disk->in_flight--; | |
3205 | } | |
3206 | if (req->end_io) | |
3207 | req->end_io(req); | |
3208 | else | |
3209 | __blk_put_request(req->q, req); | |
3210 | } | |
3211 | ||
3212 | EXPORT_SYMBOL(end_that_request_last); | |
3213 | ||
3214 | void end_request(struct request *req, int uptodate) | |
3215 | { | |
3216 | if (!end_that_request_first(req, uptodate, req->hard_cur_sectors)) { | |
3217 | add_disk_randomness(req->rq_disk); | |
3218 | blkdev_dequeue_request(req); | |
3219 | end_that_request_last(req); | |
3220 | } | |
3221 | } | |
3222 | ||
3223 | EXPORT_SYMBOL(end_request); | |
3224 | ||
3225 | void blk_rq_bio_prep(request_queue_t *q, struct request *rq, struct bio *bio) | |
3226 | { | |
3227 | /* first three bits are identical in rq->flags and bio->bi_rw */ | |
3228 | rq->flags |= (bio->bi_rw & 7); | |
3229 | ||
3230 | rq->nr_phys_segments = bio_phys_segments(q, bio); | |
3231 | rq->nr_hw_segments = bio_hw_segments(q, bio); | |
3232 | rq->current_nr_sectors = bio_cur_sectors(bio); | |
3233 | rq->hard_cur_sectors = rq->current_nr_sectors; | |
3234 | rq->hard_nr_sectors = rq->nr_sectors = bio_sectors(bio); | |
3235 | rq->buffer = bio_data(bio); | |
3236 | ||
3237 | rq->bio = rq->biotail = bio; | |
3238 | } | |
3239 | ||
3240 | EXPORT_SYMBOL(blk_rq_bio_prep); | |
3241 | ||
3242 | int kblockd_schedule_work(struct work_struct *work) | |
3243 | { | |
3244 | return queue_work(kblockd_workqueue, work); | |
3245 | } | |
3246 | ||
3247 | EXPORT_SYMBOL(kblockd_schedule_work); | |
3248 | ||
3249 | void kblockd_flush(void) | |
3250 | { | |
3251 | flush_workqueue(kblockd_workqueue); | |
3252 | } | |
3253 | EXPORT_SYMBOL(kblockd_flush); | |
3254 | ||
3255 | int __init blk_dev_init(void) | |
3256 | { | |
3257 | kblockd_workqueue = create_workqueue("kblockd"); | |
3258 | if (!kblockd_workqueue) | |
3259 | panic("Failed to create kblockd\n"); | |
3260 | ||
3261 | request_cachep = kmem_cache_create("blkdev_requests", | |
3262 | sizeof(struct request), 0, SLAB_PANIC, NULL, NULL); | |
3263 | ||
3264 | requestq_cachep = kmem_cache_create("blkdev_queue", | |
3265 | sizeof(request_queue_t), 0, SLAB_PANIC, NULL, NULL); | |
3266 | ||
3267 | iocontext_cachep = kmem_cache_create("blkdev_ioc", | |
3268 | sizeof(struct io_context), 0, SLAB_PANIC, NULL, NULL); | |
3269 | ||
3270 | blk_max_low_pfn = max_low_pfn; | |
3271 | blk_max_pfn = max_pfn; | |
3272 | ||
3273 | return 0; | |
3274 | } | |
3275 | ||
3276 | /* | |
3277 | * IO Context helper functions | |
3278 | */ | |
3279 | void put_io_context(struct io_context *ioc) | |
3280 | { | |
3281 | if (ioc == NULL) | |
3282 | return; | |
3283 | ||
3284 | BUG_ON(atomic_read(&ioc->refcount) == 0); | |
3285 | ||
3286 | if (atomic_dec_and_test(&ioc->refcount)) { | |
3287 | if (ioc->aic && ioc->aic->dtor) | |
3288 | ioc->aic->dtor(ioc->aic); | |
3289 | if (ioc->cic && ioc->cic->dtor) | |
3290 | ioc->cic->dtor(ioc->cic); | |
3291 | ||
3292 | kmem_cache_free(iocontext_cachep, ioc); | |
3293 | } | |
3294 | } | |
3295 | EXPORT_SYMBOL(put_io_context); | |
3296 | ||
3297 | /* Called by the exitting task */ | |
3298 | void exit_io_context(void) | |
3299 | { | |
3300 | unsigned long flags; | |
3301 | struct io_context *ioc; | |
3302 | ||
3303 | local_irq_save(flags); | |
3304 | ioc = current->io_context; | |
3305 | current->io_context = NULL; | |
3306 | local_irq_restore(flags); | |
3307 | ||
3308 | if (ioc->aic && ioc->aic->exit) | |
3309 | ioc->aic->exit(ioc->aic); | |
3310 | if (ioc->cic && ioc->cic->exit) | |
3311 | ioc->cic->exit(ioc->cic); | |
3312 | ||
3313 | put_io_context(ioc); | |
3314 | } | |
3315 | ||
3316 | /* | |
3317 | * If the current task has no IO context then create one and initialise it. | |
3318 | * If it does have a context, take a ref on it. | |
3319 | * | |
3320 | * This is always called in the context of the task which submitted the I/O. | |
3321 | * But weird things happen, so we disable local interrupts to ensure exclusive | |
3322 | * access to *current. | |
3323 | */ | |
3324 | struct io_context *get_io_context(int gfp_flags) | |
3325 | { | |
3326 | struct task_struct *tsk = current; | |
3327 | unsigned long flags; | |
3328 | struct io_context *ret; | |
3329 | ||
3330 | local_irq_save(flags); | |
3331 | ret = tsk->io_context; | |
3332 | if (ret) | |
3333 | goto out; | |
3334 | ||
3335 | local_irq_restore(flags); | |
3336 | ||
3337 | ret = kmem_cache_alloc(iocontext_cachep, gfp_flags); | |
3338 | if (ret) { | |
3339 | atomic_set(&ret->refcount, 1); | |
3340 | ret->pid = tsk->pid; | |
3341 | ret->last_waited = jiffies; /* doesn't matter... */ | |
3342 | ret->nr_batch_requests = 0; /* because this is 0 */ | |
3343 | ret->aic = NULL; | |
3344 | ret->cic = NULL; | |
3345 | spin_lock_init(&ret->lock); | |
3346 | ||
3347 | local_irq_save(flags); | |
3348 | ||
3349 | /* | |
3350 | * very unlikely, someone raced with us in setting up the task | |
3351 | * io context. free new context and just grab a reference. | |
3352 | */ | |
3353 | if (!tsk->io_context) | |
3354 | tsk->io_context = ret; | |
3355 | else { | |
3356 | kmem_cache_free(iocontext_cachep, ret); | |
3357 | ret = tsk->io_context; | |
3358 | } | |
3359 | ||
3360 | out: | |
3361 | atomic_inc(&ret->refcount); | |
3362 | local_irq_restore(flags); | |
3363 | } | |
3364 | ||
3365 | return ret; | |
3366 | } | |
3367 | EXPORT_SYMBOL(get_io_context); | |
3368 | ||
3369 | void copy_io_context(struct io_context **pdst, struct io_context **psrc) | |
3370 | { | |
3371 | struct io_context *src = *psrc; | |
3372 | struct io_context *dst = *pdst; | |
3373 | ||
3374 | if (src) { | |
3375 | BUG_ON(atomic_read(&src->refcount) == 0); | |
3376 | atomic_inc(&src->refcount); | |
3377 | put_io_context(dst); | |
3378 | *pdst = src; | |
3379 | } | |
3380 | } | |
3381 | EXPORT_SYMBOL(copy_io_context); | |
3382 | ||
3383 | void swap_io_context(struct io_context **ioc1, struct io_context **ioc2) | |
3384 | { | |
3385 | struct io_context *temp; | |
3386 | temp = *ioc1; | |
3387 | *ioc1 = *ioc2; | |
3388 | *ioc2 = temp; | |
3389 | } | |
3390 | EXPORT_SYMBOL(swap_io_context); | |
3391 | ||
3392 | /* | |
3393 | * sysfs parts below | |
3394 | */ | |
3395 | struct queue_sysfs_entry { | |
3396 | struct attribute attr; | |
3397 | ssize_t (*show)(struct request_queue *, char *); | |
3398 | ssize_t (*store)(struct request_queue *, const char *, size_t); | |
3399 | }; | |
3400 | ||
3401 | static ssize_t | |
3402 | queue_var_show(unsigned int var, char *page) | |
3403 | { | |
3404 | return sprintf(page, "%d\n", var); | |
3405 | } | |
3406 | ||
3407 | static ssize_t | |
3408 | queue_var_store(unsigned long *var, const char *page, size_t count) | |
3409 | { | |
3410 | char *p = (char *) page; | |
3411 | ||
3412 | *var = simple_strtoul(p, &p, 10); | |
3413 | return count; | |
3414 | } | |
3415 | ||
3416 | static ssize_t queue_requests_show(struct request_queue *q, char *page) | |
3417 | { | |
3418 | return queue_var_show(q->nr_requests, (page)); | |
3419 | } | |
3420 | ||
3421 | static ssize_t | |
3422 | queue_requests_store(struct request_queue *q, const char *page, size_t count) | |
3423 | { | |
3424 | struct request_list *rl = &q->rq; | |
3425 | ||
3426 | int ret = queue_var_store(&q->nr_requests, page, count); | |
3427 | if (q->nr_requests < BLKDEV_MIN_RQ) | |
3428 | q->nr_requests = BLKDEV_MIN_RQ; | |
3429 | blk_queue_congestion_threshold(q); | |
3430 | ||
3431 | if (rl->count[READ] >= queue_congestion_on_threshold(q)) | |
3432 | set_queue_congested(q, READ); | |
3433 | else if (rl->count[READ] < queue_congestion_off_threshold(q)) | |
3434 | clear_queue_congested(q, READ); | |
3435 | ||
3436 | if (rl->count[WRITE] >= queue_congestion_on_threshold(q)) | |
3437 | set_queue_congested(q, WRITE); | |
3438 | else if (rl->count[WRITE] < queue_congestion_off_threshold(q)) | |
3439 | clear_queue_congested(q, WRITE); | |
3440 | ||
3441 | if (rl->count[READ] >= q->nr_requests) { | |
3442 | blk_set_queue_full(q, READ); | |
3443 | } else if (rl->count[READ]+1 <= q->nr_requests) { | |
3444 | blk_clear_queue_full(q, READ); | |
3445 | wake_up(&rl->wait[READ]); | |
3446 | } | |
3447 | ||
3448 | if (rl->count[WRITE] >= q->nr_requests) { | |
3449 | blk_set_queue_full(q, WRITE); | |
3450 | } else if (rl->count[WRITE]+1 <= q->nr_requests) { | |
3451 | blk_clear_queue_full(q, WRITE); | |
3452 | wake_up(&rl->wait[WRITE]); | |
3453 | } | |
3454 | return ret; | |
3455 | } | |
3456 | ||
3457 | static ssize_t queue_ra_show(struct request_queue *q, char *page) | |
3458 | { | |
3459 | int ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10); | |
3460 | ||
3461 | return queue_var_show(ra_kb, (page)); | |
3462 | } | |
3463 | ||
3464 | static ssize_t | |
3465 | queue_ra_store(struct request_queue *q, const char *page, size_t count) | |
3466 | { | |
3467 | unsigned long ra_kb; | |
3468 | ssize_t ret = queue_var_store(&ra_kb, page, count); | |
3469 | ||
3470 | spin_lock_irq(q->queue_lock); | |
3471 | if (ra_kb > (q->max_sectors >> 1)) | |
3472 | ra_kb = (q->max_sectors >> 1); | |
3473 | ||
3474 | q->backing_dev_info.ra_pages = ra_kb >> (PAGE_CACHE_SHIFT - 10); | |
3475 | spin_unlock_irq(q->queue_lock); | |
3476 | ||
3477 | return ret; | |
3478 | } | |
3479 | ||
3480 | static ssize_t queue_max_sectors_show(struct request_queue *q, char *page) | |
3481 | { | |
3482 | int max_sectors_kb = q->max_sectors >> 1; | |
3483 | ||
3484 | return queue_var_show(max_sectors_kb, (page)); | |
3485 | } | |
3486 | ||
3487 | static ssize_t | |
3488 | queue_max_sectors_store(struct request_queue *q, const char *page, size_t count) | |
3489 | { | |
3490 | unsigned long max_sectors_kb, | |
3491 | max_hw_sectors_kb = q->max_hw_sectors >> 1, | |
3492 | page_kb = 1 << (PAGE_CACHE_SHIFT - 10); | |
3493 | ssize_t ret = queue_var_store(&max_sectors_kb, page, count); | |
3494 | int ra_kb; | |
3495 | ||
3496 | if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb) | |
3497 | return -EINVAL; | |
3498 | /* | |
3499 | * Take the queue lock to update the readahead and max_sectors | |
3500 | * values synchronously: | |
3501 | */ | |
3502 | spin_lock_irq(q->queue_lock); | |
3503 | /* | |
3504 | * Trim readahead window as well, if necessary: | |
3505 | */ | |
3506 | ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10); | |
3507 | if (ra_kb > max_sectors_kb) | |
3508 | q->backing_dev_info.ra_pages = | |
3509 | max_sectors_kb >> (PAGE_CACHE_SHIFT - 10); | |
3510 | ||
3511 | q->max_sectors = max_sectors_kb << 1; | |
3512 | spin_unlock_irq(q->queue_lock); | |
3513 | ||
3514 | return ret; | |
3515 | } | |
3516 | ||
3517 | static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page) | |
3518 | { | |
3519 | int max_hw_sectors_kb = q->max_hw_sectors >> 1; | |
3520 | ||
3521 | return queue_var_show(max_hw_sectors_kb, (page)); | |
3522 | } | |
3523 | ||
3524 | ||
3525 | static struct queue_sysfs_entry queue_requests_entry = { | |
3526 | .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR }, | |
3527 | .show = queue_requests_show, | |
3528 | .store = queue_requests_store, | |
3529 | }; | |
3530 | ||
3531 | static struct queue_sysfs_entry queue_ra_entry = { | |
3532 | .attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR }, | |
3533 | .show = queue_ra_show, | |
3534 | .store = queue_ra_store, | |
3535 | }; | |
3536 | ||
3537 | static struct queue_sysfs_entry queue_max_sectors_entry = { | |
3538 | .attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR }, | |
3539 | .show = queue_max_sectors_show, | |
3540 | .store = queue_max_sectors_store, | |
3541 | }; | |
3542 | ||
3543 | static struct queue_sysfs_entry queue_max_hw_sectors_entry = { | |
3544 | .attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO }, | |
3545 | .show = queue_max_hw_sectors_show, | |
3546 | }; | |
3547 | ||
3548 | static struct queue_sysfs_entry queue_iosched_entry = { | |
3549 | .attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR }, | |
3550 | .show = elv_iosched_show, | |
3551 | .store = elv_iosched_store, | |
3552 | }; | |
3553 | ||
3554 | static struct attribute *default_attrs[] = { | |
3555 | &queue_requests_entry.attr, | |
3556 | &queue_ra_entry.attr, | |
3557 | &queue_max_hw_sectors_entry.attr, | |
3558 | &queue_max_sectors_entry.attr, | |
3559 | &queue_iosched_entry.attr, | |
3560 | NULL, | |
3561 | }; | |
3562 | ||
3563 | #define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr) | |
3564 | ||
3565 | static ssize_t | |
3566 | queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page) | |
3567 | { | |
3568 | struct queue_sysfs_entry *entry = to_queue(attr); | |
3569 | struct request_queue *q; | |
3570 | ||
3571 | q = container_of(kobj, struct request_queue, kobj); | |
3572 | if (!entry->show) | |
6c1852a0 | 3573 | return -EIO; |
1da177e4 LT |
3574 | |
3575 | return entry->show(q, page); | |
3576 | } | |
3577 | ||
3578 | static ssize_t | |
3579 | queue_attr_store(struct kobject *kobj, struct attribute *attr, | |
3580 | const char *page, size_t length) | |
3581 | { | |
3582 | struct queue_sysfs_entry *entry = to_queue(attr); | |
3583 | struct request_queue *q; | |
3584 | ||
3585 | q = container_of(kobj, struct request_queue, kobj); | |
3586 | if (!entry->store) | |
6c1852a0 | 3587 | return -EIO; |
1da177e4 LT |
3588 | |
3589 | return entry->store(q, page, length); | |
3590 | } | |
3591 | ||
3592 | static struct sysfs_ops queue_sysfs_ops = { | |
3593 | .show = queue_attr_show, | |
3594 | .store = queue_attr_store, | |
3595 | }; | |
3596 | ||
3597 | struct kobj_type queue_ktype = { | |
3598 | .sysfs_ops = &queue_sysfs_ops, | |
3599 | .default_attrs = default_attrs, | |
3600 | }; | |
3601 | ||
3602 | int blk_register_queue(struct gendisk *disk) | |
3603 | { | |
3604 | int ret; | |
3605 | ||
3606 | request_queue_t *q = disk->queue; | |
3607 | ||
3608 | if (!q || !q->request_fn) | |
3609 | return -ENXIO; | |
3610 | ||
3611 | q->kobj.parent = kobject_get(&disk->kobj); | |
3612 | if (!q->kobj.parent) | |
3613 | return -EBUSY; | |
3614 | ||
3615 | snprintf(q->kobj.name, KOBJ_NAME_LEN, "%s", "queue"); | |
3616 | q->kobj.ktype = &queue_ktype; | |
3617 | ||
3618 | ret = kobject_register(&q->kobj); | |
3619 | if (ret < 0) | |
3620 | return ret; | |
3621 | ||
3622 | ret = elv_register_queue(q); | |
3623 | if (ret) { | |
3624 | kobject_unregister(&q->kobj); | |
3625 | return ret; | |
3626 | } | |
3627 | ||
3628 | return 0; | |
3629 | } | |
3630 | ||
3631 | void blk_unregister_queue(struct gendisk *disk) | |
3632 | { | |
3633 | request_queue_t *q = disk->queue; | |
3634 | ||
3635 | if (q && q->request_fn) { | |
3636 | elv_unregister_queue(q); | |
3637 | ||
3638 | kobject_unregister(&q->kobj); | |
3639 | kobject_put(&disk->kobj); | |
3640 | } | |
3641 | } |