blob: f20eba22b14b254553933848e94f3f4192552603 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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>
31
32/*
33 * for max sense size
34 */
35#include <scsi/scsi_cmnd.h>
36
37static void blk_unplug_work(void *data);
38static void blk_unplug_timeout(unsigned long data);
39
40/*
41 * For the allocated request tables
42 */
43static kmem_cache_t *request_cachep;
44
45/*
46 * For queue allocation
47 */
48static kmem_cache_t *requestq_cachep;
49
50/*
51 * For io context allocations
52 */
53static kmem_cache_t *iocontext_cachep;
54
55static wait_queue_head_t congestion_wqh[2] = {
56 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
57 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
58 };
59
60/*
61 * Controlling structure to kblockd
62 */
63static struct workqueue_struct *kblockd_workqueue;
64
65unsigned long blk_max_low_pfn, blk_max_pfn;
66
67EXPORT_SYMBOL(blk_max_low_pfn);
68EXPORT_SYMBOL(blk_max_pfn);
69
70/* Amount of time in which a process may batch requests */
71#define BLK_BATCH_TIME (HZ/50UL)
72
73/* Number of requests a "batching" process may submit */
74#define BLK_BATCH_REQ 32
75
76/*
77 * Return the threshold (number of used requests) at which the queue is
78 * considered to be congested. It include a little hysteresis to keep the
79 * context switch rate down.
80 */
81static inline int queue_congestion_on_threshold(struct request_queue *q)
82{
83 return q->nr_congestion_on;
84}
85
86/*
87 * The threshold at which a queue is considered to be uncongested
88 */
89static inline int queue_congestion_off_threshold(struct request_queue *q)
90{
91 return q->nr_congestion_off;
92}
93
94static void blk_queue_congestion_threshold(struct request_queue *q)
95{
96 int nr;
97
98 nr = q->nr_requests - (q->nr_requests / 8) + 1;
99 if (nr > q->nr_requests)
100 nr = q->nr_requests;
101 q->nr_congestion_on = nr;
102
103 nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1;
104 if (nr < 1)
105 nr = 1;
106 q->nr_congestion_off = nr;
107}
108
109/*
110 * A queue has just exitted congestion. Note this in the global counter of
111 * congested queues, and wake up anyone who was waiting for requests to be
112 * put back.
113 */
114static void clear_queue_congested(request_queue_t *q, int rw)
115{
116 enum bdi_state bit;
117 wait_queue_head_t *wqh = &congestion_wqh[rw];
118
119 bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
120 clear_bit(bit, &q->backing_dev_info.state);
121 smp_mb__after_clear_bit();
122 if (waitqueue_active(wqh))
123 wake_up(wqh);
124}
125
126/*
127 * A queue has just entered congestion. Flag that in the queue's VM-visible
128 * state flags and increment the global gounter of congested queues.
129 */
130static void set_queue_congested(request_queue_t *q, int rw)
131{
132 enum bdi_state bit;
133
134 bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
135 set_bit(bit, &q->backing_dev_info.state);
136}
137
138/**
139 * blk_get_backing_dev_info - get the address of a queue's backing_dev_info
140 * @bdev: device
141 *
142 * Locates the passed device's request queue and returns the address of its
143 * backing_dev_info
144 *
145 * Will return NULL if the request queue cannot be located.
146 */
147struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev)
148{
149 struct backing_dev_info *ret = NULL;
150 request_queue_t *q = bdev_get_queue(bdev);
151
152 if (q)
153 ret = &q->backing_dev_info;
154 return ret;
155}
156
157EXPORT_SYMBOL(blk_get_backing_dev_info);
158
159void blk_queue_activity_fn(request_queue_t *q, activity_fn *fn, void *data)
160{
161 q->activity_fn = fn;
162 q->activity_data = data;
163}
164
165EXPORT_SYMBOL(blk_queue_activity_fn);
166
167/**
168 * blk_queue_prep_rq - set a prepare_request function for queue
169 * @q: queue
170 * @pfn: prepare_request function
171 *
172 * It's possible for a queue to register a prepare_request callback which
173 * is invoked before the request is handed to the request_fn. The goal of
174 * the function is to prepare a request for I/O, it can be used to build a
175 * cdb from the request data for instance.
176 *
177 */
178void blk_queue_prep_rq(request_queue_t *q, prep_rq_fn *pfn)
179{
180 q->prep_rq_fn = pfn;
181}
182
183EXPORT_SYMBOL(blk_queue_prep_rq);
184
185/**
186 * blk_queue_merge_bvec - set a merge_bvec function for queue
187 * @q: queue
188 * @mbfn: merge_bvec_fn
189 *
190 * Usually queues have static limitations on the max sectors or segments that
191 * we can put in a request. Stacking drivers may have some settings that
192 * are dynamic, and thus we have to query the queue whether it is ok to
193 * add a new bio_vec to a bio at a given offset or not. If the block device
194 * has such limitations, it needs to register a merge_bvec_fn to control
195 * the size of bio's sent to it. Note that a block device *must* allow a
196 * single page to be added to an empty bio. The block device driver may want
197 * to use the bio_split() function to deal with these bio's. By default
198 * no merge_bvec_fn is defined for a queue, and only the fixed limits are
199 * honored.
200 */
201void blk_queue_merge_bvec(request_queue_t *q, merge_bvec_fn *mbfn)
202{
203 q->merge_bvec_fn = mbfn;
204}
205
206EXPORT_SYMBOL(blk_queue_merge_bvec);
207
208/**
209 * blk_queue_make_request - define an alternate make_request function for a device
210 * @q: the request queue for the device to be affected
211 * @mfn: the alternate make_request function
212 *
213 * Description:
214 * The normal way for &struct bios to be passed to a device
215 * driver is for them to be collected into requests on a request
216 * queue, and then to allow the device driver to select requests
217 * off that queue when it is ready. This works well for many block
218 * devices. However some block devices (typically virtual devices
219 * such as md or lvm) do not benefit from the processing on the
220 * request queue, and are served best by having the requests passed
221 * directly to them. This can be achieved by providing a function
222 * to blk_queue_make_request().
223 *
224 * Caveat:
225 * The driver that does this *must* be able to deal appropriately
226 * with buffers in "highmemory". This can be accomplished by either calling
227 * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling
228 * blk_queue_bounce() to create a buffer in normal memory.
229 **/
230void blk_queue_make_request(request_queue_t * q, make_request_fn * mfn)
231{
232 /*
233 * set defaults
234 */
235 q->nr_requests = BLKDEV_MAX_RQ;
236 q->max_phys_segments = MAX_PHYS_SEGMENTS;
237 q->max_hw_segments = MAX_HW_SEGMENTS;
238 q->make_request_fn = mfn;
239 q->backing_dev_info.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
240 q->backing_dev_info.state = 0;
241 q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY;
242 blk_queue_max_sectors(q, MAX_SECTORS);
243 blk_queue_hardsect_size(q, 512);
244 blk_queue_dma_alignment(q, 511);
245 blk_queue_congestion_threshold(q);
246 q->nr_batching = BLK_BATCH_REQ;
247
248 q->unplug_thresh = 4; /* hmm */
249 q->unplug_delay = (3 * HZ) / 1000; /* 3 milliseconds */
250 if (q->unplug_delay == 0)
251 q->unplug_delay = 1;
252
253 INIT_WORK(&q->unplug_work, blk_unplug_work, q);
254
255 q->unplug_timer.function = blk_unplug_timeout;
256 q->unplug_timer.data = (unsigned long)q;
257
258 /*
259 * by default assume old behaviour and bounce for any highmem page
260 */
261 blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH);
262
263 blk_queue_activity_fn(q, NULL, NULL);
264
265 INIT_LIST_HEAD(&q->drain_list);
266}
267
268EXPORT_SYMBOL(blk_queue_make_request);
269
270static inline void rq_init(request_queue_t *q, struct request *rq)
271{
272 INIT_LIST_HEAD(&rq->queuelist);
273
274 rq->errors = 0;
275 rq->rq_status = RQ_ACTIVE;
276 rq->bio = rq->biotail = NULL;
277 rq->buffer = NULL;
278 rq->ref_count = 1;
279 rq->q = q;
280 rq->waiting = NULL;
281 rq->special = NULL;
282 rq->data_len = 0;
283 rq->data = NULL;
284 rq->sense = NULL;
285 rq->end_io = NULL;
286 rq->end_io_data = NULL;
287}
288
289/**
290 * blk_queue_ordered - does this queue support ordered writes
291 * @q: the request queue
292 * @flag: see below
293 *
294 * Description:
295 * For journalled file systems, doing ordered writes on a commit
296 * block instead of explicitly doing wait_on_buffer (which is bad
297 * for performance) can be a big win. Block drivers supporting this
298 * feature should call this function and indicate so.
299 *
300 **/
301void blk_queue_ordered(request_queue_t *q, int flag)
302{
303 switch (flag) {
304 case QUEUE_ORDERED_NONE:
305 if (q->flush_rq)
306 kmem_cache_free(request_cachep, q->flush_rq);
307 q->flush_rq = NULL;
308 q->ordered = flag;
309 break;
310 case QUEUE_ORDERED_TAG:
311 q->ordered = flag;
312 break;
313 case QUEUE_ORDERED_FLUSH:
314 q->ordered = flag;
315 if (!q->flush_rq)
316 q->flush_rq = kmem_cache_alloc(request_cachep,
317 GFP_KERNEL);
318 break;
319 default:
320 printk("blk_queue_ordered: bad value %d\n", flag);
321 break;
322 }
323}
324
325EXPORT_SYMBOL(blk_queue_ordered);
326
327/**
328 * blk_queue_issue_flush_fn - set function for issuing a flush
329 * @q: the request queue
330 * @iff: the function to be called issuing the flush
331 *
332 * Description:
333 * If a driver supports issuing a flush command, the support is notified
334 * to the block layer by defining it through this call.
335 *
336 **/
337void blk_queue_issue_flush_fn(request_queue_t *q, issue_flush_fn *iff)
338{
339 q->issue_flush_fn = iff;
340}
341
342EXPORT_SYMBOL(blk_queue_issue_flush_fn);
343
344/*
345 * Cache flushing for ordered writes handling
346 */
347static void blk_pre_flush_end_io(struct request *flush_rq)
348{
349 struct request *rq = flush_rq->end_io_data;
350 request_queue_t *q = rq->q;
351
352 rq->flags |= REQ_BAR_PREFLUSH;
353
354 if (!flush_rq->errors)
355 elv_requeue_request(q, rq);
356 else {
357 q->end_flush_fn(q, flush_rq);
358 clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags);
359 q->request_fn(q);
360 }
361}
362
363static void blk_post_flush_end_io(struct request *flush_rq)
364{
365 struct request *rq = flush_rq->end_io_data;
366 request_queue_t *q = rq->q;
367
368 rq->flags |= REQ_BAR_POSTFLUSH;
369
370 q->end_flush_fn(q, flush_rq);
371 clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags);
372 q->request_fn(q);
373}
374
375struct request *blk_start_pre_flush(request_queue_t *q, struct request *rq)
376{
377 struct request *flush_rq = q->flush_rq;
378
379 BUG_ON(!blk_barrier_rq(rq));
380
381 if (test_and_set_bit(QUEUE_FLAG_FLUSH, &q->queue_flags))
382 return NULL;
383
384 rq_init(q, flush_rq);
385 flush_rq->elevator_private = NULL;
386 flush_rq->flags = REQ_BAR_FLUSH;
387 flush_rq->rq_disk = rq->rq_disk;
388 flush_rq->rl = NULL;
389
390 /*
391 * prepare_flush returns 0 if no flush is needed, just mark both
392 * pre and post flush as done in that case
393 */
394 if (!q->prepare_flush_fn(q, flush_rq)) {
395 rq->flags |= REQ_BAR_PREFLUSH | REQ_BAR_POSTFLUSH;
396 clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags);
397 return rq;
398 }
399
400 /*
401 * some drivers dequeue requests right away, some only after io
402 * completion. make sure the request is dequeued.
403 */
404 if (!list_empty(&rq->queuelist))
405 blkdev_dequeue_request(rq);
406
407 elv_deactivate_request(q, rq);
408
409 flush_rq->end_io_data = rq;
410 flush_rq->end_io = blk_pre_flush_end_io;
411
412 __elv_add_request(q, flush_rq, ELEVATOR_INSERT_FRONT, 0);
413 return flush_rq;
414}
415
416static void blk_start_post_flush(request_queue_t *q, struct request *rq)
417{
418 struct request *flush_rq = q->flush_rq;
419
420 BUG_ON(!blk_barrier_rq(rq));
421
422 rq_init(q, flush_rq);
423 flush_rq->elevator_private = NULL;
424 flush_rq->flags = REQ_BAR_FLUSH;
425 flush_rq->rq_disk = rq->rq_disk;
426 flush_rq->rl = NULL;
427
428 if (q->prepare_flush_fn(q, flush_rq)) {
429 flush_rq->end_io_data = rq;
430 flush_rq->end_io = blk_post_flush_end_io;
431
432 __elv_add_request(q, flush_rq, ELEVATOR_INSERT_FRONT, 0);
433 q->request_fn(q);
434 }
435}
436
437static inline int blk_check_end_barrier(request_queue_t *q, struct request *rq,
438 int sectors)
439{
440 if (sectors > rq->nr_sectors)
441 sectors = rq->nr_sectors;
442
443 rq->nr_sectors -= sectors;
444 return rq->nr_sectors;
445}
446
447static int __blk_complete_barrier_rq(request_queue_t *q, struct request *rq,
448 int sectors, int queue_locked)
449{
450 if (q->ordered != QUEUE_ORDERED_FLUSH)
451 return 0;
452 if (!blk_fs_request(rq) || !blk_barrier_rq(rq))
453 return 0;
454 if (blk_barrier_postflush(rq))
455 return 0;
456
457 if (!blk_check_end_barrier(q, rq, sectors)) {
458 unsigned long flags = 0;
459
460 if (!queue_locked)
461 spin_lock_irqsave(q->queue_lock, flags);
462
463 blk_start_post_flush(q, rq);
464
465 if (!queue_locked)
466 spin_unlock_irqrestore(q->queue_lock, flags);
467 }
468
469 return 1;
470}
471
472/**
473 * blk_complete_barrier_rq - complete possible barrier request
474 * @q: the request queue for the device
475 * @rq: the request
476 * @sectors: number of sectors to complete
477 *
478 * Description:
479 * Used in driver end_io handling to determine whether to postpone
480 * completion of a barrier request until a post flush has been done. This
481 * is the unlocked variant, used if the caller doesn't already hold the
482 * queue lock.
483 **/
484int blk_complete_barrier_rq(request_queue_t *q, struct request *rq, int sectors)
485{
486 return __blk_complete_barrier_rq(q, rq, sectors, 0);
487}
488EXPORT_SYMBOL(blk_complete_barrier_rq);
489
490/**
491 * blk_complete_barrier_rq_locked - complete possible barrier request
492 * @q: the request queue for the device
493 * @rq: the request
494 * @sectors: number of sectors to complete
495 *
496 * Description:
497 * See blk_complete_barrier_rq(). This variant must be used if the caller
498 * holds the queue lock.
499 **/
500int blk_complete_barrier_rq_locked(request_queue_t *q, struct request *rq,
501 int sectors)
502{
503 return __blk_complete_barrier_rq(q, rq, sectors, 1);
504}
505EXPORT_SYMBOL(blk_complete_barrier_rq_locked);
506
507/**
508 * blk_queue_bounce_limit - set bounce buffer limit for queue
509 * @q: the request queue for the device
510 * @dma_addr: bus address limit
511 *
512 * Description:
513 * Different hardware can have different requirements as to what pages
514 * it can do I/O directly to. A low level driver can call
515 * blk_queue_bounce_limit to have lower memory pages allocated as bounce
516 * buffers for doing I/O to pages residing above @page. By default
517 * the block layer sets this to the highest numbered "low" memory page.
518 **/
519void blk_queue_bounce_limit(request_queue_t *q, u64 dma_addr)
520{
521 unsigned long bounce_pfn = dma_addr >> PAGE_SHIFT;
522
523 /*
524 * set appropriate bounce gfp mask -- unfortunately we don't have a
525 * full 4GB zone, so we have to resort to low memory for any bounces.
526 * ISA has its own < 16MB zone.
527 */
528 if (bounce_pfn < blk_max_low_pfn) {
529 BUG_ON(dma_addr < BLK_BOUNCE_ISA);
530 init_emergency_isa_pool();
531 q->bounce_gfp = GFP_NOIO | GFP_DMA;
532 } else
533 q->bounce_gfp = GFP_NOIO;
534
535 q->bounce_pfn = bounce_pfn;
536}
537
538EXPORT_SYMBOL(blk_queue_bounce_limit);
539
540/**
541 * blk_queue_max_sectors - set max sectors for a request for this queue
542 * @q: the request queue for the device
543 * @max_sectors: max sectors in the usual 512b unit
544 *
545 * Description:
546 * Enables a low level driver to set an upper limit on the size of
547 * received requests.
548 **/
549void blk_queue_max_sectors(request_queue_t *q, unsigned short max_sectors)
550{
551 if ((max_sectors << 9) < PAGE_CACHE_SIZE) {
552 max_sectors = 1 << (PAGE_CACHE_SHIFT - 9);
553 printk("%s: set to minimum %d\n", __FUNCTION__, max_sectors);
554 }
555
556 q->max_sectors = q->max_hw_sectors = max_sectors;
557}
558
559EXPORT_SYMBOL(blk_queue_max_sectors);
560
561/**
562 * blk_queue_max_phys_segments - set max phys segments for a request for this queue
563 * @q: the request queue for the device
564 * @max_segments: max number of segments
565 *
566 * Description:
567 * Enables a low level driver to set an upper limit on the number of
568 * physical data segments in a request. This would be the largest sized
569 * scatter list the driver could handle.
570 **/
571void blk_queue_max_phys_segments(request_queue_t *q, unsigned short max_segments)
572{
573 if (!max_segments) {
574 max_segments = 1;
575 printk("%s: set to minimum %d\n", __FUNCTION__, max_segments);
576 }
577
578 q->max_phys_segments = max_segments;
579}
580
581EXPORT_SYMBOL(blk_queue_max_phys_segments);
582
583/**
584 * blk_queue_max_hw_segments - set max hw segments for a request for this queue
585 * @q: the request queue for the device
586 * @max_segments: max number of segments
587 *
588 * Description:
589 * Enables a low level driver to set an upper limit on the number of
590 * hw data segments in a request. This would be the largest number of
591 * address/length pairs the host adapter can actually give as once
592 * to the device.
593 **/
594void blk_queue_max_hw_segments(request_queue_t *q, unsigned short max_segments)
595{
596 if (!max_segments) {
597 max_segments = 1;
598 printk("%s: set to minimum %d\n", __FUNCTION__, max_segments);
599 }
600
601 q->max_hw_segments = max_segments;
602}
603
604EXPORT_SYMBOL(blk_queue_max_hw_segments);
605
606/**
607 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
608 * @q: the request queue for the device
609 * @max_size: max size of segment in bytes
610 *
611 * Description:
612 * Enables a low level driver to set an upper limit on the size of a
613 * coalesced segment
614 **/
615void blk_queue_max_segment_size(request_queue_t *q, unsigned int max_size)
616{
617 if (max_size < PAGE_CACHE_SIZE) {
618 max_size = PAGE_CACHE_SIZE;
619 printk("%s: set to minimum %d\n", __FUNCTION__, max_size);
620 }
621
622 q->max_segment_size = max_size;
623}
624
625EXPORT_SYMBOL(blk_queue_max_segment_size);
626
627/**
628 * blk_queue_hardsect_size - set hardware sector size for the queue
629 * @q: the request queue for the device
630 * @size: the hardware sector size, in bytes
631 *
632 * Description:
633 * This should typically be set to the lowest possible sector size
634 * that the hardware can operate on (possible without reverting to
635 * even internal read-modify-write operations). Usually the default
636 * of 512 covers most hardware.
637 **/
638void blk_queue_hardsect_size(request_queue_t *q, unsigned short size)
639{
640 q->hardsect_size = size;
641}
642
643EXPORT_SYMBOL(blk_queue_hardsect_size);
644
645/*
646 * Returns the minimum that is _not_ zero, unless both are zero.
647 */
648#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
649
650/**
651 * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
652 * @t: the stacking driver (top)
653 * @b: the underlying device (bottom)
654 **/
655void blk_queue_stack_limits(request_queue_t *t, request_queue_t *b)
656{
657 /* zero is "infinity" */
658 t->max_sectors = t->max_hw_sectors =
659 min_not_zero(t->max_sectors,b->max_sectors);
660
661 t->max_phys_segments = min(t->max_phys_segments,b->max_phys_segments);
662 t->max_hw_segments = min(t->max_hw_segments,b->max_hw_segments);
663 t->max_segment_size = min(t->max_segment_size,b->max_segment_size);
664 t->hardsect_size = max(t->hardsect_size,b->hardsect_size);
665}
666
667EXPORT_SYMBOL(blk_queue_stack_limits);
668
669/**
670 * blk_queue_segment_boundary - set boundary rules for segment merging
671 * @q: the request queue for the device
672 * @mask: the memory boundary mask
673 **/
674void blk_queue_segment_boundary(request_queue_t *q, unsigned long mask)
675{
676 if (mask < PAGE_CACHE_SIZE - 1) {
677 mask = PAGE_CACHE_SIZE - 1;
678 printk("%s: set to minimum %lx\n", __FUNCTION__, mask);
679 }
680
681 q->seg_boundary_mask = mask;
682}
683
684EXPORT_SYMBOL(blk_queue_segment_boundary);
685
686/**
687 * blk_queue_dma_alignment - set dma length and memory alignment
688 * @q: the request queue for the device
689 * @mask: alignment mask
690 *
691 * description:
692 * set required memory and length aligment for direct dma transactions.
693 * this is used when buiding direct io requests for the queue.
694 *
695 **/
696void blk_queue_dma_alignment(request_queue_t *q, int mask)
697{
698 q->dma_alignment = mask;
699}
700
701EXPORT_SYMBOL(blk_queue_dma_alignment);
702
703/**
704 * blk_queue_find_tag - find a request by its tag and queue
705 *
706 * @q: The request queue for the device
707 * @tag: The tag of the request
708 *
709 * Notes:
710 * Should be used when a device returns a tag and you want to match
711 * it with a request.
712 *
713 * no locks need be held.
714 **/
715struct request *blk_queue_find_tag(request_queue_t *q, int tag)
716{
717 struct blk_queue_tag *bqt = q->queue_tags;
718
719 if (unlikely(bqt == NULL || tag >= bqt->real_max_depth))
720 return NULL;
721
722 return bqt->tag_index[tag];
723}
724
725EXPORT_SYMBOL(blk_queue_find_tag);
726
727/**
728 * __blk_queue_free_tags - release tag maintenance info
729 * @q: the request queue for the device
730 *
731 * Notes:
732 * blk_cleanup_queue() will take care of calling this function, if tagging
733 * has been used. So there's no need to call this directly.
734 **/
735static void __blk_queue_free_tags(request_queue_t *q)
736{
737 struct blk_queue_tag *bqt = q->queue_tags;
738
739 if (!bqt)
740 return;
741
742 if (atomic_dec_and_test(&bqt->refcnt)) {
743 BUG_ON(bqt->busy);
744 BUG_ON(!list_empty(&bqt->busy_list));
745
746 kfree(bqt->tag_index);
747 bqt->tag_index = NULL;
748
749 kfree(bqt->tag_map);
750 bqt->tag_map = NULL;
751
752 kfree(bqt);
753 }
754
755 q->queue_tags = NULL;
756 q->queue_flags &= ~(1 << QUEUE_FLAG_QUEUED);
757}
758
759/**
760 * blk_queue_free_tags - release tag maintenance info
761 * @q: the request queue for the device
762 *
763 * Notes:
764 * This is used to disabled tagged queuing to a device, yet leave
765 * queue in function.
766 **/
767void blk_queue_free_tags(request_queue_t *q)
768{
769 clear_bit(QUEUE_FLAG_QUEUED, &q->queue_flags);
770}
771
772EXPORT_SYMBOL(blk_queue_free_tags);
773
774static int
775init_tag_map(request_queue_t *q, struct blk_queue_tag *tags, int depth)
776{
777 int bits, i;
778 struct request **tag_index;
779 unsigned long *tag_map;
780
781 if (depth > q->nr_requests * 2) {
782 depth = q->nr_requests * 2;
783 printk(KERN_ERR "%s: adjusted depth to %d\n",
784 __FUNCTION__, depth);
785 }
786
787 tag_index = kmalloc(depth * sizeof(struct request *), GFP_ATOMIC);
788 if (!tag_index)
789 goto fail;
790
791 bits = (depth / BLK_TAGS_PER_LONG) + 1;
792 tag_map = kmalloc(bits * sizeof(unsigned long), GFP_ATOMIC);
793 if (!tag_map)
794 goto fail;
795
796 memset(tag_index, 0, depth * sizeof(struct request *));
797 memset(tag_map, 0, bits * sizeof(unsigned long));
798 tags->max_depth = depth;
799 tags->real_max_depth = bits * BITS_PER_LONG;
800 tags->tag_index = tag_index;
801 tags->tag_map = tag_map;
802
803 /*
804 * set the upper bits if the depth isn't a multiple of the word size
805 */
806 for (i = depth; i < bits * BLK_TAGS_PER_LONG; i++)
807 __set_bit(i, tag_map);
808
809 return 0;
810fail:
811 kfree(tag_index);
812 return -ENOMEM;
813}
814
815/**
816 * blk_queue_init_tags - initialize the queue tag info
817 * @q: the request queue for the device
818 * @depth: the maximum queue depth supported
819 * @tags: the tag to use
820 **/
821int blk_queue_init_tags(request_queue_t *q, int depth,
822 struct blk_queue_tag *tags)
823{
824 int rc;
825
826 BUG_ON(tags && q->queue_tags && tags != q->queue_tags);
827
828 if (!tags && !q->queue_tags) {
829 tags = kmalloc(sizeof(struct blk_queue_tag), GFP_ATOMIC);
830 if (!tags)
831 goto fail;
832
833 if (init_tag_map(q, tags, depth))
834 goto fail;
835
836 INIT_LIST_HEAD(&tags->busy_list);
837 tags->busy = 0;
838 atomic_set(&tags->refcnt, 1);
839 } else if (q->queue_tags) {
840 if ((rc = blk_queue_resize_tags(q, depth)))
841 return rc;
842 set_bit(QUEUE_FLAG_QUEUED, &q->queue_flags);
843 return 0;
844 } else
845 atomic_inc(&tags->refcnt);
846
847 /*
848 * assign it, all done
849 */
850 q->queue_tags = tags;
851 q->queue_flags |= (1 << QUEUE_FLAG_QUEUED);
852 return 0;
853fail:
854 kfree(tags);
855 return -ENOMEM;
856}
857
858EXPORT_SYMBOL(blk_queue_init_tags);
859
860/**
861 * blk_queue_resize_tags - change the queueing depth
862 * @q: the request queue for the device
863 * @new_depth: the new max command queueing depth
864 *
865 * Notes:
866 * Must be called with the queue lock held.
867 **/
868int blk_queue_resize_tags(request_queue_t *q, int new_depth)
869{
870 struct blk_queue_tag *bqt = q->queue_tags;
871 struct request **tag_index;
872 unsigned long *tag_map;
873 int bits, max_depth;
874
875 if (!bqt)
876 return -ENXIO;
877
878 /*
879 * don't bother sizing down
880 */
881 if (new_depth <= bqt->real_max_depth) {
882 bqt->max_depth = new_depth;
883 return 0;
884 }
885
886 /*
887 * save the old state info, so we can copy it back
888 */
889 tag_index = bqt->tag_index;
890 tag_map = bqt->tag_map;
891 max_depth = bqt->real_max_depth;
892
893 if (init_tag_map(q, bqt, new_depth))
894 return -ENOMEM;
895
896 memcpy(bqt->tag_index, tag_index, max_depth * sizeof(struct request *));
897 bits = max_depth / BLK_TAGS_PER_LONG;
898 memcpy(bqt->tag_map, tag_map, bits * sizeof(unsigned long));
899
900 kfree(tag_index);
901 kfree(tag_map);
902 return 0;
903}
904
905EXPORT_SYMBOL(blk_queue_resize_tags);
906
907/**
908 * blk_queue_end_tag - end tag operations for a request
909 * @q: the request queue for the device
910 * @rq: the request that has completed
911 *
912 * Description:
913 * Typically called when end_that_request_first() returns 0, meaning
914 * all transfers have been done for a request. It's important to call
915 * this function before end_that_request_last(), as that will put the
916 * request back on the free list thus corrupting the internal tag list.
917 *
918 * Notes:
919 * queue lock must be held.
920 **/
921void blk_queue_end_tag(request_queue_t *q, struct request *rq)
922{
923 struct blk_queue_tag *bqt = q->queue_tags;
924 int tag = rq->tag;
925
926 BUG_ON(tag == -1);
927
928 if (unlikely(tag >= bqt->real_max_depth))
929 return;
930
931 if (unlikely(!__test_and_clear_bit(tag, bqt->tag_map))) {
932 printk("attempt to clear non-busy tag (%d)\n", tag);
933 return;
934 }
935
936 list_del_init(&rq->queuelist);
937 rq->flags &= ~REQ_QUEUED;
938 rq->tag = -1;
939
940 if (unlikely(bqt->tag_index[tag] == NULL))
941 printk("tag %d is missing\n", tag);
942
943 bqt->tag_index[tag] = NULL;
944 bqt->busy--;
945}
946
947EXPORT_SYMBOL(blk_queue_end_tag);
948
949/**
950 * blk_queue_start_tag - find a free tag and assign it
951 * @q: the request queue for the device
952 * @rq: the block request that needs tagging
953 *
954 * Description:
955 * This can either be used as a stand-alone helper, or possibly be
956 * assigned as the queue &prep_rq_fn (in which case &struct request
957 * automagically gets a tag assigned). Note that this function
958 * assumes that any type of request can be queued! if this is not
959 * true for your device, you must check the request type before
960 * calling this function. The request will also be removed from
961 * the request queue, so it's the drivers responsibility to readd
962 * it if it should need to be restarted for some reason.
963 *
964 * Notes:
965 * queue lock must be held.
966 **/
967int blk_queue_start_tag(request_queue_t *q, struct request *rq)
968{
969 struct blk_queue_tag *bqt = q->queue_tags;
970 unsigned long *map = bqt->tag_map;
971 int tag = 0;
972
973 if (unlikely((rq->flags & REQ_QUEUED))) {
974 printk(KERN_ERR
975 "request %p for device [%s] already tagged %d",
976 rq, rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->tag);
977 BUG();
978 }
979
980 for (map = bqt->tag_map; *map == -1UL; map++) {
981 tag += BLK_TAGS_PER_LONG;
982
983 if (tag >= bqt->max_depth)
984 return 1;
985 }
986
987 tag += ffz(*map);
988 __set_bit(tag, bqt->tag_map);
989
990 rq->flags |= REQ_QUEUED;
991 rq->tag = tag;
992 bqt->tag_index[tag] = rq;
993 blkdev_dequeue_request(rq);
994 list_add(&rq->queuelist, &bqt->busy_list);
995 bqt->busy++;
996 return 0;
997}
998
999EXPORT_SYMBOL(blk_queue_start_tag);
1000
1001/**
1002 * blk_queue_invalidate_tags - invalidate all pending tags
1003 * @q: the request queue for the device
1004 *
1005 * Description:
1006 * Hardware conditions may dictate a need to stop all pending requests.
1007 * In this case, we will safely clear the block side of the tag queue and
1008 * readd all requests to the request queue in the right order.
1009 *
1010 * Notes:
1011 * queue lock must be held.
1012 **/
1013void blk_queue_invalidate_tags(request_queue_t *q)
1014{
1015 struct blk_queue_tag *bqt = q->queue_tags;
1016 struct list_head *tmp, *n;
1017 struct request *rq;
1018
1019 list_for_each_safe(tmp, n, &bqt->busy_list) {
1020 rq = list_entry_rq(tmp);
1021
1022 if (rq->tag == -1) {
1023 printk("bad tag found on list\n");
1024 list_del_init(&rq->queuelist);
1025 rq->flags &= ~REQ_QUEUED;
1026 } else
1027 blk_queue_end_tag(q, rq);
1028
1029 rq->flags &= ~REQ_STARTED;
1030 __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0);
1031 }
1032}
1033
1034EXPORT_SYMBOL(blk_queue_invalidate_tags);
1035
1036static char *rq_flags[] = {
1037 "REQ_RW",
1038 "REQ_FAILFAST",
1039 "REQ_SOFTBARRIER",
1040 "REQ_HARDBARRIER",
1041 "REQ_CMD",
1042 "REQ_NOMERGE",
1043 "REQ_STARTED",
1044 "REQ_DONTPREP",
1045 "REQ_QUEUED",
1046 "REQ_PC",
1047 "REQ_BLOCK_PC",
1048 "REQ_SENSE",
1049 "REQ_FAILED",
1050 "REQ_QUIET",
1051 "REQ_SPECIAL",
1052 "REQ_DRIVE_CMD",
1053 "REQ_DRIVE_TASK",
1054 "REQ_DRIVE_TASKFILE",
1055 "REQ_PREEMPT",
1056 "REQ_PM_SUSPEND",
1057 "REQ_PM_RESUME",
1058 "REQ_PM_SHUTDOWN",
1059};
1060
1061void blk_dump_rq_flags(struct request *rq, char *msg)
1062{
1063 int bit;
1064
1065 printk("%s: dev %s: flags = ", msg,
1066 rq->rq_disk ? rq->rq_disk->disk_name : "?");
1067 bit = 0;
1068 do {
1069 if (rq->flags & (1 << bit))
1070 printk("%s ", rq_flags[bit]);
1071 bit++;
1072 } while (bit < __REQ_NR_BITS);
1073
1074 printk("\nsector %llu, nr/cnr %lu/%u\n", (unsigned long long)rq->sector,
1075 rq->nr_sectors,
1076 rq->current_nr_sectors);
1077 printk("bio %p, biotail %p, buffer %p, data %p, len %u\n", rq->bio, rq->biotail, rq->buffer, rq->data, rq->data_len);
1078
1079 if (rq->flags & (REQ_BLOCK_PC | REQ_PC)) {
1080 printk("cdb: ");
1081 for (bit = 0; bit < sizeof(rq->cmd); bit++)
1082 printk("%02x ", rq->cmd[bit]);
1083 printk("\n");
1084 }
1085}
1086
1087EXPORT_SYMBOL(blk_dump_rq_flags);
1088
1089void blk_recount_segments(request_queue_t *q, struct bio *bio)
1090{
1091 struct bio_vec *bv, *bvprv = NULL;
1092 int i, nr_phys_segs, nr_hw_segs, seg_size, hw_seg_size, cluster;
1093 int high, highprv = 1;
1094
1095 if (unlikely(!bio->bi_io_vec))
1096 return;
1097
1098 cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
1099 hw_seg_size = seg_size = nr_phys_segs = nr_hw_segs = 0;
1100 bio_for_each_segment(bv, bio, i) {
1101 /*
1102 * the trick here is making sure that a high page is never
1103 * considered part of another segment, since that might
1104 * change with the bounce page.
1105 */
1106 high = page_to_pfn(bv->bv_page) >= q->bounce_pfn;
1107 if (high || highprv)
1108 goto new_hw_segment;
1109 if (cluster) {
1110 if (seg_size + bv->bv_len > q->max_segment_size)
1111 goto new_segment;
1112 if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv))
1113 goto new_segment;
1114 if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv))
1115 goto new_segment;
1116 if (BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len))
1117 goto new_hw_segment;
1118
1119 seg_size += bv->bv_len;
1120 hw_seg_size += bv->bv_len;
1121 bvprv = bv;
1122 continue;
1123 }
1124new_segment:
1125 if (BIOVEC_VIRT_MERGEABLE(bvprv, bv) &&
1126 !BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len)) {
1127 hw_seg_size += bv->bv_len;
1128 } else {
1129new_hw_segment:
1130 if (hw_seg_size > bio->bi_hw_front_size)
1131 bio->bi_hw_front_size = hw_seg_size;
1132 hw_seg_size = BIOVEC_VIRT_START_SIZE(bv) + bv->bv_len;
1133 nr_hw_segs++;
1134 }
1135
1136 nr_phys_segs++;
1137 bvprv = bv;
1138 seg_size = bv->bv_len;
1139 highprv = high;
1140 }
1141 if (hw_seg_size > bio->bi_hw_back_size)
1142 bio->bi_hw_back_size = hw_seg_size;
1143 if (nr_hw_segs == 1 && hw_seg_size > bio->bi_hw_front_size)
1144 bio->bi_hw_front_size = hw_seg_size;
1145 bio->bi_phys_segments = nr_phys_segs;
1146 bio->bi_hw_segments = nr_hw_segs;
1147 bio->bi_flags |= (1 << BIO_SEG_VALID);
1148}
1149
1150
1151int blk_phys_contig_segment(request_queue_t *q, struct bio *bio,
1152 struct bio *nxt)
1153{
1154 if (!(q->queue_flags & (1 << QUEUE_FLAG_CLUSTER)))
1155 return 0;
1156
1157 if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)))
1158 return 0;
1159 if (bio->bi_size + nxt->bi_size > q->max_segment_size)
1160 return 0;
1161
1162 /*
1163 * bio and nxt are contigous in memory, check if the queue allows
1164 * these two to be merged into one
1165 */
1166 if (BIO_SEG_BOUNDARY(q, bio, nxt))
1167 return 1;
1168
1169 return 0;
1170}
1171
1172EXPORT_SYMBOL(blk_phys_contig_segment);
1173
1174int blk_hw_contig_segment(request_queue_t *q, struct bio *bio,
1175 struct bio *nxt)
1176{
1177 if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
1178 blk_recount_segments(q, bio);
1179 if (unlikely(!bio_flagged(nxt, BIO_SEG_VALID)))
1180 blk_recount_segments(q, nxt);
1181 if (!BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)) ||
1182 BIOVEC_VIRT_OVERSIZE(bio->bi_hw_front_size + bio->bi_hw_back_size))
1183 return 0;
1184 if (bio->bi_size + nxt->bi_size > q->max_segment_size)
1185 return 0;
1186
1187 return 1;
1188}
1189
1190EXPORT_SYMBOL(blk_hw_contig_segment);
1191
1192/*
1193 * map a request to scatterlist, return number of sg entries setup. Caller
1194 * must make sure sg can hold rq->nr_phys_segments entries
1195 */
1196int blk_rq_map_sg(request_queue_t *q, struct request *rq, struct scatterlist *sg)
1197{
1198 struct bio_vec *bvec, *bvprv;
1199 struct bio *bio;
1200 int nsegs, i, cluster;
1201
1202 nsegs = 0;
1203 cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
1204
1205 /*
1206 * for each bio in rq
1207 */
1208 bvprv = NULL;
1209 rq_for_each_bio(bio, rq) {
1210 /*
1211 * for each segment in bio
1212 */
1213 bio_for_each_segment(bvec, bio, i) {
1214 int nbytes = bvec->bv_len;
1215
1216 if (bvprv && cluster) {
1217 if (sg[nsegs - 1].length + nbytes > q->max_segment_size)
1218 goto new_segment;
1219
1220 if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec))
1221 goto new_segment;
1222 if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec))
1223 goto new_segment;
1224
1225 sg[nsegs - 1].length += nbytes;
1226 } else {
1227new_segment:
1228 memset(&sg[nsegs],0,sizeof(struct scatterlist));
1229 sg[nsegs].page = bvec->bv_page;
1230 sg[nsegs].length = nbytes;
1231 sg[nsegs].offset = bvec->bv_offset;
1232
1233 nsegs++;
1234 }
1235 bvprv = bvec;
1236 } /* segments in bio */
1237 } /* bios in rq */
1238
1239 return nsegs;
1240}
1241
1242EXPORT_SYMBOL(blk_rq_map_sg);
1243
1244/*
1245 * the standard queue merge functions, can be overridden with device
1246 * specific ones if so desired
1247 */
1248
1249static inline int ll_new_mergeable(request_queue_t *q,
1250 struct request *req,
1251 struct bio *bio)
1252{
1253 int nr_phys_segs = bio_phys_segments(q, bio);
1254
1255 if (req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) {
1256 req->flags |= REQ_NOMERGE;
1257 if (req == q->last_merge)
1258 q->last_merge = NULL;
1259 return 0;
1260 }
1261
1262 /*
1263 * A hw segment is just getting larger, bump just the phys
1264 * counter.
1265 */
1266 req->nr_phys_segments += nr_phys_segs;
1267 return 1;
1268}
1269
1270static inline int ll_new_hw_segment(request_queue_t *q,
1271 struct request *req,
1272 struct bio *bio)
1273{
1274 int nr_hw_segs = bio_hw_segments(q, bio);
1275 int nr_phys_segs = bio_phys_segments(q, bio);
1276
1277 if (req->nr_hw_segments + nr_hw_segs > q->max_hw_segments
1278 || req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) {
1279 req->flags |= REQ_NOMERGE;
1280 if (req == q->last_merge)
1281 q->last_merge = NULL;
1282 return 0;
1283 }
1284
1285 /*
1286 * This will form the start of a new hw segment. Bump both
1287 * counters.
1288 */
1289 req->nr_hw_segments += nr_hw_segs;
1290 req->nr_phys_segments += nr_phys_segs;
1291 return 1;
1292}
1293
1294static int ll_back_merge_fn(request_queue_t *q, struct request *req,
1295 struct bio *bio)
1296{
1297 int len;
1298
1299 if (req->nr_sectors + bio_sectors(bio) > q->max_sectors) {
1300 req->flags |= REQ_NOMERGE;
1301 if (req == q->last_merge)
1302 q->last_merge = NULL;
1303 return 0;
1304 }
1305 if (unlikely(!bio_flagged(req->biotail, BIO_SEG_VALID)))
1306 blk_recount_segments(q, req->biotail);
1307 if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
1308 blk_recount_segments(q, bio);
1309 len = req->biotail->bi_hw_back_size + bio->bi_hw_front_size;
1310 if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req->biotail), __BVEC_START(bio)) &&
1311 !BIOVEC_VIRT_OVERSIZE(len)) {
1312 int mergeable = ll_new_mergeable(q, req, bio);
1313
1314 if (mergeable) {
1315 if (req->nr_hw_segments == 1)
1316 req->bio->bi_hw_front_size = len;
1317 if (bio->bi_hw_segments == 1)
1318 bio->bi_hw_back_size = len;
1319 }
1320 return mergeable;
1321 }
1322
1323 return ll_new_hw_segment(q, req, bio);
1324}
1325
1326static int ll_front_merge_fn(request_queue_t *q, struct request *req,
1327 struct bio *bio)
1328{
1329 int len;
1330
1331 if (req->nr_sectors + bio_sectors(bio) > q->max_sectors) {
1332 req->flags |= REQ_NOMERGE;
1333 if (req == q->last_merge)
1334 q->last_merge = NULL;
1335 return 0;
1336 }
1337 len = bio->bi_hw_back_size + req->bio->bi_hw_front_size;
1338 if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
1339 blk_recount_segments(q, bio);
1340 if (unlikely(!bio_flagged(req->bio, BIO_SEG_VALID)))
1341 blk_recount_segments(q, req->bio);
1342 if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(req->bio)) &&
1343 !BIOVEC_VIRT_OVERSIZE(len)) {
1344 int mergeable = ll_new_mergeable(q, req, bio);
1345
1346 if (mergeable) {
1347 if (bio->bi_hw_segments == 1)
1348 bio->bi_hw_front_size = len;
1349 if (req->nr_hw_segments == 1)
1350 req->biotail->bi_hw_back_size = len;
1351 }
1352 return mergeable;
1353 }
1354
1355 return ll_new_hw_segment(q, req, bio);
1356}
1357
1358static int ll_merge_requests_fn(request_queue_t *q, struct request *req,
1359 struct request *next)
1360{
1361 int total_phys_segments = req->nr_phys_segments +next->nr_phys_segments;
1362 int total_hw_segments = req->nr_hw_segments + next->nr_hw_segments;
1363
1364 /*
1365 * First check if the either of the requests are re-queued
1366 * requests. Can't merge them if they are.
1367 */
1368 if (req->special || next->special)
1369 return 0;
1370
1371 /*
1372 * Will it become to large?
1373 */
1374 if ((req->nr_sectors + next->nr_sectors) > q->max_sectors)
1375 return 0;
1376
1377 total_phys_segments = req->nr_phys_segments + next->nr_phys_segments;
1378 if (blk_phys_contig_segment(q, req->biotail, next->bio))
1379 total_phys_segments--;
1380
1381 if (total_phys_segments > q->max_phys_segments)
1382 return 0;
1383
1384 total_hw_segments = req->nr_hw_segments + next->nr_hw_segments;
1385 if (blk_hw_contig_segment(q, req->biotail, next->bio)) {
1386 int len = req->biotail->bi_hw_back_size + next->bio->bi_hw_front_size;
1387 /*
1388 * propagate the combined length to the end of the requests
1389 */
1390 if (req->nr_hw_segments == 1)
1391 req->bio->bi_hw_front_size = len;
1392 if (next->nr_hw_segments == 1)
1393 next->biotail->bi_hw_back_size = len;
1394 total_hw_segments--;
1395 }
1396
1397 if (total_hw_segments > q->max_hw_segments)
1398 return 0;
1399
1400 /* Merge is OK... */
1401 req->nr_phys_segments = total_phys_segments;
1402 req->nr_hw_segments = total_hw_segments;
1403 return 1;
1404}
1405
1406/*
1407 * "plug" the device if there are no outstanding requests: this will
1408 * force the transfer to start only after we have put all the requests
1409 * on the list.
1410 *
1411 * This is called with interrupts off and no requests on the queue and
1412 * with the queue lock held.
1413 */
1414void blk_plug_device(request_queue_t *q)
1415{
1416 WARN_ON(!irqs_disabled());
1417
1418 /*
1419 * don't plug a stopped queue, it must be paired with blk_start_queue()
1420 * which will restart the queueing
1421 */
1422 if (test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags))
1423 return;
1424
1425 if (!test_and_set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags))
1426 mod_timer(&q->unplug_timer, jiffies + q->unplug_delay);
1427}
1428
1429EXPORT_SYMBOL(blk_plug_device);
1430
1431/*
1432 * remove the queue from the plugged list, if present. called with
1433 * queue lock held and interrupts disabled.
1434 */
1435int blk_remove_plug(request_queue_t *q)
1436{
1437 WARN_ON(!irqs_disabled());
1438
1439 if (!test_and_clear_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags))
1440 return 0;
1441
1442 del_timer(&q->unplug_timer);
1443 return 1;
1444}
1445
1446EXPORT_SYMBOL(blk_remove_plug);
1447
1448/*
1449 * remove the plug and let it rip..
1450 */
1451void __generic_unplug_device(request_queue_t *q)
1452{
1453 if (test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags))
1454 return;
1455
1456 if (!blk_remove_plug(q))
1457 return;
1458
1459 /*
1460 * was plugged, fire request_fn if queue has stuff to do
1461 */
1462 if (elv_next_request(q))
1463 q->request_fn(q);
1464}
1465EXPORT_SYMBOL(__generic_unplug_device);
1466
1467/**
1468 * generic_unplug_device - fire a request queue
1469 * @q: The &request_queue_t in question
1470 *
1471 * Description:
1472 * Linux uses plugging to build bigger requests queues before letting
1473 * the device have at them. If a queue is plugged, the I/O scheduler
1474 * is still adding and merging requests on the queue. Once the queue
1475 * gets unplugged, the request_fn defined for the queue is invoked and
1476 * transfers started.
1477 **/
1478void generic_unplug_device(request_queue_t *q)
1479{
1480 spin_lock_irq(q->queue_lock);
1481 __generic_unplug_device(q);
1482 spin_unlock_irq(q->queue_lock);
1483}
1484EXPORT_SYMBOL(generic_unplug_device);
1485
1486static void blk_backing_dev_unplug(struct backing_dev_info *bdi,
1487 struct page *page)
1488{
1489 request_queue_t *q = bdi->unplug_io_data;
1490
1491 /*
1492 * devices don't necessarily have an ->unplug_fn defined
1493 */
1494 if (q->unplug_fn)
1495 q->unplug_fn(q);
1496}
1497
1498static void blk_unplug_work(void *data)
1499{
1500 request_queue_t *q = data;
1501
1502 q->unplug_fn(q);
1503}
1504
1505static void blk_unplug_timeout(unsigned long data)
1506{
1507 request_queue_t *q = (request_queue_t *)data;
1508
1509 kblockd_schedule_work(&q->unplug_work);
1510}
1511
1512/**
1513 * blk_start_queue - restart a previously stopped queue
1514 * @q: The &request_queue_t in question
1515 *
1516 * Description:
1517 * blk_start_queue() will clear the stop flag on the queue, and call
1518 * the request_fn for the queue if it was in a stopped state when
1519 * entered. Also see blk_stop_queue(). Queue lock must be held.
1520 **/
1521void blk_start_queue(request_queue_t *q)
1522{
1523 clear_bit(QUEUE_FLAG_STOPPED, &q->queue_flags);
1524
1525 /*
1526 * one level of recursion is ok and is much faster than kicking
1527 * the unplug handling
1528 */
1529 if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) {
1530 q->request_fn(q);
1531 clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags);
1532 } else {
1533 blk_plug_device(q);
1534 kblockd_schedule_work(&q->unplug_work);
1535 }
1536}
1537
1538EXPORT_SYMBOL(blk_start_queue);
1539
1540/**
1541 * blk_stop_queue - stop a queue
1542 * @q: The &request_queue_t in question
1543 *
1544 * Description:
1545 * The Linux block layer assumes that a block driver will consume all
1546 * entries on the request queue when the request_fn strategy is called.
1547 * Often this will not happen, because of hardware limitations (queue
1548 * depth settings). If a device driver gets a 'queue full' response,
1549 * or if it simply chooses not to queue more I/O at one point, it can
1550 * call this function to prevent the request_fn from being called until
1551 * the driver has signalled it's ready to go again. This happens by calling
1552 * blk_start_queue() to restart queue operations. Queue lock must be held.
1553 **/
1554void blk_stop_queue(request_queue_t *q)
1555{
1556 blk_remove_plug(q);
1557 set_bit(QUEUE_FLAG_STOPPED, &q->queue_flags);
1558}
1559EXPORT_SYMBOL(blk_stop_queue);
1560
1561/**
1562 * blk_sync_queue - cancel any pending callbacks on a queue
1563 * @q: the queue
1564 *
1565 * Description:
1566 * The block layer may perform asynchronous callback activity
1567 * on a queue, such as calling the unplug function after a timeout.
1568 * A block device may call blk_sync_queue to ensure that any
1569 * such activity is cancelled, thus allowing it to release resources
1570 * the the callbacks might use. The caller must already have made sure
1571 * that its ->make_request_fn will not re-add plugging prior to calling
1572 * this function.
1573 *
1574 */
1575void blk_sync_queue(struct request_queue *q)
1576{
1577 del_timer_sync(&q->unplug_timer);
1578 kblockd_flush();
1579}
1580EXPORT_SYMBOL(blk_sync_queue);
1581
1582/**
1583 * blk_run_queue - run a single device queue
1584 * @q: The queue to run
1585 */
1586void blk_run_queue(struct request_queue *q)
1587{
1588 unsigned long flags;
1589
1590 spin_lock_irqsave(q->queue_lock, flags);
1591 blk_remove_plug(q);
Ken Chena2997382005-04-16 15:25:43 -07001592 if (!elv_queue_empty(q))
1593 q->request_fn(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001594 spin_unlock_irqrestore(q->queue_lock, flags);
1595}
1596EXPORT_SYMBOL(blk_run_queue);
1597
1598/**
1599 * blk_cleanup_queue: - release a &request_queue_t when it is no longer needed
1600 * @q: the request queue to be released
1601 *
1602 * Description:
1603 * blk_cleanup_queue is the pair to blk_init_queue() or
1604 * blk_queue_make_request(). It should be called when a request queue is
1605 * being released; typically when a block device is being de-registered.
1606 * Currently, its primary task it to free all the &struct request
1607 * structures that were allocated to the queue and the queue itself.
1608 *
1609 * Caveat:
1610 * Hopefully the low level driver will have finished any
1611 * outstanding requests first...
1612 **/
1613void blk_cleanup_queue(request_queue_t * q)
1614{
1615 struct request_list *rl = &q->rq;
1616
1617 if (!atomic_dec_and_test(&q->refcnt))
1618 return;
1619
1620 if (q->elevator)
1621 elevator_exit(q->elevator);
1622
1623 blk_sync_queue(q);
1624
1625 if (rl->rq_pool)
1626 mempool_destroy(rl->rq_pool);
1627
1628 if (q->queue_tags)
1629 __blk_queue_free_tags(q);
1630
1631 blk_queue_ordered(q, QUEUE_ORDERED_NONE);
1632
1633 kmem_cache_free(requestq_cachep, q);
1634}
1635
1636EXPORT_SYMBOL(blk_cleanup_queue);
1637
1638static int blk_init_free_list(request_queue_t *q)
1639{
1640 struct request_list *rl = &q->rq;
1641
1642 rl->count[READ] = rl->count[WRITE] = 0;
1643 rl->starved[READ] = rl->starved[WRITE] = 0;
1644 init_waitqueue_head(&rl->wait[READ]);
1645 init_waitqueue_head(&rl->wait[WRITE]);
1646 init_waitqueue_head(&rl->drain);
1647
1648 rl->rq_pool = mempool_create(BLKDEV_MIN_RQ, mempool_alloc_slab, mempool_free_slab, request_cachep);
1649
1650 if (!rl->rq_pool)
1651 return -ENOMEM;
1652
1653 return 0;
1654}
1655
1656static int __make_request(request_queue_t *, struct bio *);
1657
1658request_queue_t *blk_alloc_queue(int gfp_mask)
1659{
1660 request_queue_t *q = kmem_cache_alloc(requestq_cachep, gfp_mask);
1661
1662 if (!q)
1663 return NULL;
1664
1665 memset(q, 0, sizeof(*q));
1666 init_timer(&q->unplug_timer);
1667 atomic_set(&q->refcnt, 1);
1668
1669 q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug;
1670 q->backing_dev_info.unplug_io_data = q;
1671
1672 return q;
1673}
1674
1675EXPORT_SYMBOL(blk_alloc_queue);
1676
1677/**
1678 * blk_init_queue - prepare a request queue for use with a block device
1679 * @rfn: The function to be called to process requests that have been
1680 * placed on the queue.
1681 * @lock: Request queue spin lock
1682 *
1683 * Description:
1684 * If a block device wishes to use the standard request handling procedures,
1685 * which sorts requests and coalesces adjacent requests, then it must
1686 * call blk_init_queue(). The function @rfn will be called when there
1687 * are requests on the queue that need to be processed. If the device
1688 * supports plugging, then @rfn may not be called immediately when requests
1689 * are available on the queue, but may be called at some time later instead.
1690 * Plugged queues are generally unplugged when a buffer belonging to one
1691 * of the requests on the queue is needed, or due to memory pressure.
1692 *
1693 * @rfn is not required, or even expected, to remove all requests off the
1694 * queue, but only as many as it can handle at a time. If it does leave
1695 * requests on the queue, it is responsible for arranging that the requests
1696 * get dealt with eventually.
1697 *
1698 * The queue spin lock must be held while manipulating the requests on the
1699 * request queue.
1700 *
1701 * Function returns a pointer to the initialized request queue, or NULL if
1702 * it didn't succeed.
1703 *
1704 * Note:
1705 * blk_init_queue() must be paired with a blk_cleanup_queue() call
1706 * when the block device is deactivated (such as at module unload).
1707 **/
1708request_queue_t *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock)
1709{
1710 request_queue_t *q = blk_alloc_queue(GFP_KERNEL);
1711
1712 if (!q)
1713 return NULL;
1714
1715 if (blk_init_free_list(q))
1716 goto out_init;
1717
152587d2005-04-12 16:22:06 -05001718 /*
1719 * if caller didn't supply a lock, they get per-queue locking with
1720 * our embedded lock
1721 */
1722 if (!lock) {
1723 spin_lock_init(&q->__queue_lock);
1724 lock = &q->__queue_lock;
1725 }
1726
Linus Torvalds1da177e2005-04-16 15:20:36 -07001727 q->request_fn = rfn;
1728 q->back_merge_fn = ll_back_merge_fn;
1729 q->front_merge_fn = ll_front_merge_fn;
1730 q->merge_requests_fn = ll_merge_requests_fn;
1731 q->prep_rq_fn = NULL;
1732 q->unplug_fn = generic_unplug_device;
1733 q->queue_flags = (1 << QUEUE_FLAG_CLUSTER);
1734 q->queue_lock = lock;
1735
1736 blk_queue_segment_boundary(q, 0xffffffff);
1737
1738 blk_queue_make_request(q, __make_request);
1739 blk_queue_max_segment_size(q, MAX_SEGMENT_SIZE);
1740
1741 blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS);
1742 blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS);
1743
1744 /*
1745 * all done
1746 */
1747 if (!elevator_init(q, NULL)) {
1748 blk_queue_congestion_threshold(q);
1749 return q;
1750 }
1751
1752 blk_cleanup_queue(q);
1753out_init:
1754 kmem_cache_free(requestq_cachep, q);
1755 return NULL;
1756}
1757
1758EXPORT_SYMBOL(blk_init_queue);
1759
1760int blk_get_queue(request_queue_t *q)
1761{
1762 if (!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
1763 atomic_inc(&q->refcnt);
1764 return 0;
1765 }
1766
1767 return 1;
1768}
1769
1770EXPORT_SYMBOL(blk_get_queue);
1771
1772static inline void blk_free_request(request_queue_t *q, struct request *rq)
1773{
1774 elv_put_request(q, rq);
1775 mempool_free(rq, q->rq.rq_pool);
1776}
1777
1778static inline struct request *blk_alloc_request(request_queue_t *q, int rw,
1779 int gfp_mask)
1780{
1781 struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask);
1782
1783 if (!rq)
1784 return NULL;
1785
1786 /*
1787 * first three bits are identical in rq->flags and bio->bi_rw,
1788 * see bio.h and blkdev.h
1789 */
1790 rq->flags = rw;
1791
1792 if (!elv_set_request(q, rq, gfp_mask))
1793 return rq;
1794
1795 mempool_free(rq, q->rq.rq_pool);
1796 return NULL;
1797}
1798
1799/*
1800 * ioc_batching returns true if the ioc is a valid batching request and
1801 * should be given priority access to a request.
1802 */
1803static inline int ioc_batching(request_queue_t *q, struct io_context *ioc)
1804{
1805 if (!ioc)
1806 return 0;
1807
1808 /*
1809 * Make sure the process is able to allocate at least 1 request
1810 * even if the batch times out, otherwise we could theoretically
1811 * lose wakeups.
1812 */
1813 return ioc->nr_batch_requests == q->nr_batching ||
1814 (ioc->nr_batch_requests > 0
1815 && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME));
1816}
1817
1818/*
1819 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
1820 * will cause the process to be a "batcher" on all queues in the system. This
1821 * is the behaviour we want though - once it gets a wakeup it should be given
1822 * a nice run.
1823 */
1824void ioc_set_batching(request_queue_t *q, struct io_context *ioc)
1825{
1826 if (!ioc || ioc_batching(q, ioc))
1827 return;
1828
1829 ioc->nr_batch_requests = q->nr_batching;
1830 ioc->last_waited = jiffies;
1831}
1832
1833static void __freed_request(request_queue_t *q, int rw)
1834{
1835 struct request_list *rl = &q->rq;
1836
1837 if (rl->count[rw] < queue_congestion_off_threshold(q))
1838 clear_queue_congested(q, rw);
1839
1840 if (rl->count[rw] + 1 <= q->nr_requests) {
1841 smp_mb();
1842 if (waitqueue_active(&rl->wait[rw]))
1843 wake_up(&rl->wait[rw]);
1844
1845 blk_clear_queue_full(q, rw);
1846 }
1847}
1848
1849/*
1850 * A request has just been released. Account for it, update the full and
1851 * congestion status, wake up any waiters. Called under q->queue_lock.
1852 */
1853static void freed_request(request_queue_t *q, int rw)
1854{
1855 struct request_list *rl = &q->rq;
1856
1857 rl->count[rw]--;
1858
1859 __freed_request(q, rw);
1860
1861 if (unlikely(rl->starved[rw ^ 1]))
1862 __freed_request(q, rw ^ 1);
1863
1864 if (!rl->count[READ] && !rl->count[WRITE]) {
1865 smp_mb();
1866 if (unlikely(waitqueue_active(&rl->drain)))
1867 wake_up(&rl->drain);
1868 }
1869}
1870
1871#define blkdev_free_rq(list) list_entry((list)->next, struct request, queuelist)
1872/*
1873 * Get a free request, queue_lock must not be held
1874 */
1875static struct request *get_request(request_queue_t *q, int rw, int gfp_mask)
1876{
1877 struct request *rq = NULL;
1878 struct request_list *rl = &q->rq;
1879 struct io_context *ioc = get_io_context(gfp_mask);
1880
1881 if (unlikely(test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags)))
1882 goto out;
1883
1884 spin_lock_irq(q->queue_lock);
1885 if (rl->count[rw]+1 >= q->nr_requests) {
1886 /*
1887 * The queue will fill after this allocation, so set it as
1888 * full, and mark this process as "batching". This process
1889 * will be allowed to complete a batch of requests, others
1890 * will be blocked.
1891 */
1892 if (!blk_queue_full(q, rw)) {
1893 ioc_set_batching(q, ioc);
1894 blk_set_queue_full(q, rw);
1895 }
1896 }
1897
1898 switch (elv_may_queue(q, rw)) {
1899 case ELV_MQUEUE_NO:
1900 goto rq_starved;
1901 case ELV_MQUEUE_MAY:
1902 break;
1903 case ELV_MQUEUE_MUST:
1904 goto get_rq;
1905 }
1906
1907 if (blk_queue_full(q, rw) && !ioc_batching(q, ioc)) {
1908 /*
1909 * The queue is full and the allocating process is not a
1910 * "batcher", and not exempted by the IO scheduler
1911 */
1912 spin_unlock_irq(q->queue_lock);
1913 goto out;
1914 }
1915
1916get_rq:
1917 rl->count[rw]++;
1918 rl->starved[rw] = 0;
1919 if (rl->count[rw] >= queue_congestion_on_threshold(q))
1920 set_queue_congested(q, rw);
1921 spin_unlock_irq(q->queue_lock);
1922
1923 rq = blk_alloc_request(q, rw, gfp_mask);
1924 if (!rq) {
1925 /*
1926 * Allocation failed presumably due to memory. Undo anything
1927 * we might have messed up.
1928 *
1929 * Allocating task should really be put onto the front of the
1930 * wait queue, but this is pretty rare.
1931 */
1932 spin_lock_irq(q->queue_lock);
1933 freed_request(q, rw);
1934
1935 /*
1936 * in the very unlikely event that allocation failed and no
1937 * requests for this direction was pending, mark us starved
1938 * so that freeing of a request in the other direction will
1939 * notice us. another possible fix would be to split the
1940 * rq mempool into READ and WRITE
1941 */
1942rq_starved:
1943 if (unlikely(rl->count[rw] == 0))
1944 rl->starved[rw] = 1;
1945
1946 spin_unlock_irq(q->queue_lock);
1947 goto out;
1948 }
1949
1950 if (ioc_batching(q, ioc))
1951 ioc->nr_batch_requests--;
1952
1953 rq_init(q, rq);
1954 rq->rl = rl;
1955out:
1956 put_io_context(ioc);
1957 return rq;
1958}
1959
1960/*
1961 * No available requests for this queue, unplug the device and wait for some
1962 * requests to become available.
1963 */
1964static struct request *get_request_wait(request_queue_t *q, int rw)
1965{
1966 DEFINE_WAIT(wait);
1967 struct request *rq;
1968
1969 generic_unplug_device(q);
1970 do {
1971 struct request_list *rl = &q->rq;
1972
1973 prepare_to_wait_exclusive(&rl->wait[rw], &wait,
1974 TASK_UNINTERRUPTIBLE);
1975
1976 rq = get_request(q, rw, GFP_NOIO);
1977
1978 if (!rq) {
1979 struct io_context *ioc;
1980
1981 io_schedule();
1982
1983 /*
1984 * After sleeping, we become a "batching" process and
1985 * will be able to allocate at least one request, and
1986 * up to a big batch of them for a small period time.
1987 * See ioc_batching, ioc_set_batching
1988 */
1989 ioc = get_io_context(GFP_NOIO);
1990 ioc_set_batching(q, ioc);
1991 put_io_context(ioc);
1992 }
1993 finish_wait(&rl->wait[rw], &wait);
1994 } while (!rq);
1995
1996 return rq;
1997}
1998
1999struct request *blk_get_request(request_queue_t *q, int rw, int gfp_mask)
2000{
2001 struct request *rq;
2002
2003 BUG_ON(rw != READ && rw != WRITE);
2004
2005 if (gfp_mask & __GFP_WAIT)
2006 rq = get_request_wait(q, rw);
2007 else
2008 rq = get_request(q, rw, gfp_mask);
2009
2010 return rq;
2011}
2012
2013EXPORT_SYMBOL(blk_get_request);
2014
2015/**
2016 * blk_requeue_request - put a request back on queue
2017 * @q: request queue where request should be inserted
2018 * @rq: request to be inserted
2019 *
2020 * Description:
2021 * Drivers often keep queueing requests until the hardware cannot accept
2022 * more, when that condition happens we need to put the request back
2023 * on the queue. Must be called with queue lock held.
2024 */
2025void blk_requeue_request(request_queue_t *q, struct request *rq)
2026{
2027 if (blk_rq_tagged(rq))
2028 blk_queue_end_tag(q, rq);
2029
2030 elv_requeue_request(q, rq);
2031}
2032
2033EXPORT_SYMBOL(blk_requeue_request);
2034
2035/**
2036 * blk_insert_request - insert a special request in to a request queue
2037 * @q: request queue where request should be inserted
2038 * @rq: request to be inserted
2039 * @at_head: insert request at head or tail of queue
2040 * @data: private data
Linus Torvalds1da177e2005-04-16 15:20:36 -07002041 *
2042 * Description:
2043 * Many block devices need to execute commands asynchronously, so they don't
2044 * block the whole kernel from preemption during request execution. This is
2045 * accomplished normally by inserting aritficial requests tagged as
2046 * REQ_SPECIAL in to the corresponding request queue, and letting them be
2047 * scheduled for actual execution by the request queue.
2048 *
2049 * We have the option of inserting the head or the tail of the queue.
2050 * Typically we use the tail for new ioctls and so forth. We use the head
2051 * of the queue for things like a QUEUE_FULL message from a device, or a
2052 * host that is unable to accept a particular command.
2053 */
2054void blk_insert_request(request_queue_t *q, struct request *rq,
Tejun Heo 867d1192005-04-24 02:06:05 -05002055 int at_head, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002056{
Tejun Heo 867d1192005-04-24 02:06:05 -05002057 int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002058 unsigned long flags;
2059
2060 /*
2061 * tell I/O scheduler that this isn't a regular read/write (ie it
2062 * must not attempt merges on this) and that it acts as a soft
2063 * barrier
2064 */
2065 rq->flags |= REQ_SPECIAL | REQ_SOFTBARRIER;
2066
2067 rq->special = data;
2068
2069 spin_lock_irqsave(q->queue_lock, flags);
2070
2071 /*
2072 * If command is tagged, release the tag
2073 */
Tejun Heo 867d1192005-04-24 02:06:05 -05002074 if (blk_rq_tagged(rq))
2075 blk_queue_end_tag(q, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002076
Tejun Heo 867d1192005-04-24 02:06:05 -05002077 drive_stat_acct(rq, rq->nr_sectors, 1);
2078 __elv_add_request(q, rq, where, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002079
Linus Torvalds1da177e2005-04-16 15:20:36 -07002080 if (blk_queue_plugged(q))
2081 __generic_unplug_device(q);
2082 else
2083 q->request_fn(q);
2084 spin_unlock_irqrestore(q->queue_lock, flags);
2085}
2086
2087EXPORT_SYMBOL(blk_insert_request);
2088
2089/**
2090 * blk_rq_map_user - map user data to a request, for REQ_BLOCK_PC usage
2091 * @q: request queue where request should be inserted
2092 * @rw: READ or WRITE data
2093 * @ubuf: the user buffer
2094 * @len: length of user data
2095 *
2096 * Description:
2097 * Data will be mapped directly for zero copy io, if possible. Otherwise
2098 * a kernel bounce buffer is used.
2099 *
2100 * A matching blk_rq_unmap_user() must be issued at the end of io, while
2101 * still in process context.
2102 *
2103 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
2104 * before being submitted to the device, as pages mapped may be out of
2105 * reach. It's the callers responsibility to make sure this happens. The
2106 * original bio must be passed back in to blk_rq_unmap_user() for proper
2107 * unmapping.
2108 */
2109struct request *blk_rq_map_user(request_queue_t *q, int rw, void __user *ubuf,
2110 unsigned int len)
2111{
2112 unsigned long uaddr;
2113 struct request *rq;
2114 struct bio *bio;
2115
2116 if (len > (q->max_sectors << 9))
2117 return ERR_PTR(-EINVAL);
2118 if ((!len && ubuf) || (len && !ubuf))
2119 return ERR_PTR(-EINVAL);
2120
2121 rq = blk_get_request(q, rw, __GFP_WAIT);
2122 if (!rq)
2123 return ERR_PTR(-ENOMEM);
2124
2125 /*
2126 * if alignment requirement is satisfied, map in user pages for
2127 * direct dma. else, set up kernel bounce buffers
2128 */
2129 uaddr = (unsigned long) ubuf;
2130 if (!(uaddr & queue_dma_alignment(q)) && !(len & queue_dma_alignment(q)))
2131 bio = bio_map_user(q, NULL, uaddr, len, rw == READ);
2132 else
2133 bio = bio_copy_user(q, uaddr, len, rw == READ);
2134
2135 if (!IS_ERR(bio)) {
2136 rq->bio = rq->biotail = bio;
2137 blk_rq_bio_prep(q, rq, bio);
2138
2139 rq->buffer = rq->data = NULL;
2140 rq->data_len = len;
2141 return rq;
2142 }
2143
2144 /*
2145 * bio is the err-ptr
2146 */
2147 blk_put_request(rq);
2148 return (struct request *) bio;
2149}
2150
2151EXPORT_SYMBOL(blk_rq_map_user);
2152
2153/**
2154 * blk_rq_unmap_user - unmap a request with user data
2155 * @rq: request to be unmapped
2156 * @bio: bio for the request
2157 * @ulen: length of user buffer
2158 *
2159 * Description:
2160 * Unmap a request previously mapped by blk_rq_map_user().
2161 */
2162int blk_rq_unmap_user(struct request *rq, struct bio *bio, unsigned int ulen)
2163{
2164 int ret = 0;
2165
2166 if (bio) {
2167 if (bio_flagged(bio, BIO_USER_MAPPED))
2168 bio_unmap_user(bio);
2169 else
2170 ret = bio_uncopy_user(bio);
2171 }
2172
2173 blk_put_request(rq);
2174 return ret;
2175}
2176
2177EXPORT_SYMBOL(blk_rq_unmap_user);
2178
2179/**
2180 * blk_execute_rq - insert a request into queue for execution
2181 * @q: queue to insert the request in
2182 * @bd_disk: matching gendisk
2183 * @rq: request to insert
2184 *
2185 * Description:
2186 * Insert a fully prepared request at the back of the io scheduler queue
2187 * for execution.
2188 */
2189int blk_execute_rq(request_queue_t *q, struct gendisk *bd_disk,
2190 struct request *rq)
2191{
2192 DECLARE_COMPLETION(wait);
2193 char sense[SCSI_SENSE_BUFFERSIZE];
2194 int err = 0;
2195
2196 rq->rq_disk = bd_disk;
2197
2198 /*
2199 * we need an extra reference to the request, so we can look at
2200 * it after io completion
2201 */
2202 rq->ref_count++;
2203
2204 if (!rq->sense) {
2205 memset(sense, 0, sizeof(sense));
2206 rq->sense = sense;
2207 rq->sense_len = 0;
2208 }
2209
2210 rq->flags |= REQ_NOMERGE;
2211 rq->waiting = &wait;
2212 rq->end_io = blk_end_sync_rq;
2213 elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 1);
2214 generic_unplug_device(q);
2215 wait_for_completion(&wait);
2216 rq->waiting = NULL;
2217
2218 if (rq->errors)
2219 err = -EIO;
2220
2221 return err;
2222}
2223
2224EXPORT_SYMBOL(blk_execute_rq);
2225
2226/**
2227 * blkdev_issue_flush - queue a flush
2228 * @bdev: blockdev to issue flush for
2229 * @error_sector: error sector
2230 *
2231 * Description:
2232 * Issue a flush for the block device in question. Caller can supply
2233 * room for storing the error offset in case of a flush error, if they
2234 * wish to. Caller must run wait_for_completion() on its own.
2235 */
2236int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector)
2237{
2238 request_queue_t *q;
2239
2240 if (bdev->bd_disk == NULL)
2241 return -ENXIO;
2242
2243 q = bdev_get_queue(bdev);
2244 if (!q)
2245 return -ENXIO;
2246 if (!q->issue_flush_fn)
2247 return -EOPNOTSUPP;
2248
2249 return q->issue_flush_fn(q, bdev->bd_disk, error_sector);
2250}
2251
2252EXPORT_SYMBOL(blkdev_issue_flush);
2253
2254/**
2255 * blkdev_scsi_issue_flush_fn - issue flush for SCSI devices
2256 * @q: device queue
2257 * @disk: gendisk
2258 * @error_sector: error offset
2259 *
2260 * Description:
2261 * Devices understanding the SCSI command set, can use this function as
2262 * a helper for issuing a cache flush. Note: driver is required to store
2263 * the error offset (in case of error flushing) in ->sector of struct
2264 * request.
2265 */
2266int blkdev_scsi_issue_flush_fn(request_queue_t *q, struct gendisk *disk,
2267 sector_t *error_sector)
2268{
2269 struct request *rq = blk_get_request(q, WRITE, __GFP_WAIT);
2270 int ret;
2271
2272 rq->flags |= REQ_BLOCK_PC | REQ_SOFTBARRIER;
2273 rq->sector = 0;
2274 memset(rq->cmd, 0, sizeof(rq->cmd));
2275 rq->cmd[0] = 0x35;
2276 rq->cmd_len = 12;
2277 rq->data = NULL;
2278 rq->data_len = 0;
2279 rq->timeout = 60 * HZ;
2280
2281 ret = blk_execute_rq(q, disk, rq);
2282
2283 if (ret && error_sector)
2284 *error_sector = rq->sector;
2285
2286 blk_put_request(rq);
2287 return ret;
2288}
2289
2290EXPORT_SYMBOL(blkdev_scsi_issue_flush_fn);
2291
2292void drive_stat_acct(struct request *rq, int nr_sectors, int new_io)
2293{
2294 int rw = rq_data_dir(rq);
2295
2296 if (!blk_fs_request(rq) || !rq->rq_disk)
2297 return;
2298
2299 if (rw == READ) {
2300 __disk_stat_add(rq->rq_disk, read_sectors, nr_sectors);
2301 if (!new_io)
2302 __disk_stat_inc(rq->rq_disk, read_merges);
2303 } else if (rw == WRITE) {
2304 __disk_stat_add(rq->rq_disk, write_sectors, nr_sectors);
2305 if (!new_io)
2306 __disk_stat_inc(rq->rq_disk, write_merges);
2307 }
2308 if (new_io) {
2309 disk_round_stats(rq->rq_disk);
2310 rq->rq_disk->in_flight++;
2311 }
2312}
2313
2314/*
2315 * add-request adds a request to the linked list.
2316 * queue lock is held and interrupts disabled, as we muck with the
2317 * request queue list.
2318 */
2319static inline void add_request(request_queue_t * q, struct request * req)
2320{
2321 drive_stat_acct(req, req->nr_sectors, 1);
2322
2323 if (q->activity_fn)
2324 q->activity_fn(q->activity_data, rq_data_dir(req));
2325
2326 /*
2327 * elevator indicated where it wants this request to be
2328 * inserted at elevator_merge time
2329 */
2330 __elv_add_request(q, req, ELEVATOR_INSERT_SORT, 0);
2331}
2332
2333/*
2334 * disk_round_stats() - Round off the performance stats on a struct
2335 * disk_stats.
2336 *
2337 * The average IO queue length and utilisation statistics are maintained
2338 * by observing the current state of the queue length and the amount of
2339 * time it has been in this state for.
2340 *
2341 * Normally, that accounting is done on IO completion, but that can result
2342 * in more than a second's worth of IO being accounted for within any one
2343 * second, leading to >100% utilisation. To deal with that, we call this
2344 * function to do a round-off before returning the results when reading
2345 * /proc/diskstats. This accounts immediately for all queue usage up to
2346 * the current jiffies and restarts the counters again.
2347 */
2348void disk_round_stats(struct gendisk *disk)
2349{
2350 unsigned long now = jiffies;
2351
2352 __disk_stat_add(disk, time_in_queue,
2353 disk->in_flight * (now - disk->stamp));
2354 disk->stamp = now;
2355
2356 if (disk->in_flight)
2357 __disk_stat_add(disk, io_ticks, (now - disk->stamp_idle));
2358 disk->stamp_idle = now;
2359}
2360
2361/*
2362 * queue lock must be held
2363 */
2364static void __blk_put_request(request_queue_t *q, struct request *req)
2365{
2366 struct request_list *rl = req->rl;
2367
2368 if (unlikely(!q))
2369 return;
2370 if (unlikely(--req->ref_count))
2371 return;
2372
2373 req->rq_status = RQ_INACTIVE;
2374 req->q = NULL;
2375 req->rl = NULL;
2376
2377 /*
2378 * Request may not have originated from ll_rw_blk. if not,
2379 * it didn't come out of our reserved rq pools
2380 */
2381 if (rl) {
2382 int rw = rq_data_dir(req);
2383
2384 elv_completed_request(q, req);
2385
2386 BUG_ON(!list_empty(&req->queuelist));
2387
2388 blk_free_request(q, req);
2389 freed_request(q, rw);
2390 }
2391}
2392
2393void blk_put_request(struct request *req)
2394{
2395 /*
2396 * if req->rl isn't set, this request didnt originate from the
2397 * block layer, so it's safe to just disregard it
2398 */
2399 if (req->rl) {
2400 unsigned long flags;
2401 request_queue_t *q = req->q;
2402
2403 spin_lock_irqsave(q->queue_lock, flags);
2404 __blk_put_request(q, req);
2405 spin_unlock_irqrestore(q->queue_lock, flags);
2406 }
2407}
2408
2409EXPORT_SYMBOL(blk_put_request);
2410
2411/**
2412 * blk_end_sync_rq - executes a completion event on a request
2413 * @rq: request to complete
2414 */
2415void blk_end_sync_rq(struct request *rq)
2416{
2417 struct completion *waiting = rq->waiting;
2418
2419 rq->waiting = NULL;
2420 __blk_put_request(rq->q, rq);
2421
2422 /*
2423 * complete last, if this is a stack request the process (and thus
2424 * the rq pointer) could be invalid right after this complete()
2425 */
2426 complete(waiting);
2427}
2428EXPORT_SYMBOL(blk_end_sync_rq);
2429
2430/**
2431 * blk_congestion_wait - wait for a queue to become uncongested
2432 * @rw: READ or WRITE
2433 * @timeout: timeout in jiffies
2434 *
2435 * Waits for up to @timeout jiffies for a queue (any queue) to exit congestion.
2436 * If no queues are congested then just wait for the next request to be
2437 * returned.
2438 */
2439long blk_congestion_wait(int rw, long timeout)
2440{
2441 long ret;
2442 DEFINE_WAIT(wait);
2443 wait_queue_head_t *wqh = &congestion_wqh[rw];
2444
2445 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
2446 ret = io_schedule_timeout(timeout);
2447 finish_wait(wqh, &wait);
2448 return ret;
2449}
2450
2451EXPORT_SYMBOL(blk_congestion_wait);
2452
2453/*
2454 * Has to be called with the request spinlock acquired
2455 */
2456static int attempt_merge(request_queue_t *q, struct request *req,
2457 struct request *next)
2458{
2459 if (!rq_mergeable(req) || !rq_mergeable(next))
2460 return 0;
2461
2462 /*
2463 * not contigious
2464 */
2465 if (req->sector + req->nr_sectors != next->sector)
2466 return 0;
2467
2468 if (rq_data_dir(req) != rq_data_dir(next)
2469 || req->rq_disk != next->rq_disk
2470 || next->waiting || next->special)
2471 return 0;
2472
2473 /*
2474 * If we are allowed to merge, then append bio list
2475 * from next to rq and release next. merge_requests_fn
2476 * will have updated segment counts, update sector
2477 * counts here.
2478 */
2479 if (!q->merge_requests_fn(q, req, next))
2480 return 0;
2481
2482 /*
2483 * At this point we have either done a back merge
2484 * or front merge. We need the smaller start_time of
2485 * the merged requests to be the current request
2486 * for accounting purposes.
2487 */
2488 if (time_after(req->start_time, next->start_time))
2489 req->start_time = next->start_time;
2490
2491 req->biotail->bi_next = next->bio;
2492 req->biotail = next->biotail;
2493
2494 req->nr_sectors = req->hard_nr_sectors += next->hard_nr_sectors;
2495
2496 elv_merge_requests(q, req, next);
2497
2498 if (req->rq_disk) {
2499 disk_round_stats(req->rq_disk);
2500 req->rq_disk->in_flight--;
2501 }
2502
2503 __blk_put_request(q, next);
2504 return 1;
2505}
2506
2507static inline int attempt_back_merge(request_queue_t *q, struct request *rq)
2508{
2509 struct request *next = elv_latter_request(q, rq);
2510
2511 if (next)
2512 return attempt_merge(q, rq, next);
2513
2514 return 0;
2515}
2516
2517static inline int attempt_front_merge(request_queue_t *q, struct request *rq)
2518{
2519 struct request *prev = elv_former_request(q, rq);
2520
2521 if (prev)
2522 return attempt_merge(q, prev, rq);
2523
2524 return 0;
2525}
2526
2527/**
2528 * blk_attempt_remerge - attempt to remerge active head with next request
2529 * @q: The &request_queue_t belonging to the device
2530 * @rq: The head request (usually)
2531 *
2532 * Description:
2533 * For head-active devices, the queue can easily be unplugged so quickly
2534 * that proper merging is not done on the front request. This may hurt
2535 * performance greatly for some devices. The block layer cannot safely
2536 * do merging on that first request for these queues, but the driver can
2537 * call this function and make it happen any way. Only the driver knows
2538 * when it is safe to do so.
2539 **/
2540void blk_attempt_remerge(request_queue_t *q, struct request *rq)
2541{
2542 unsigned long flags;
2543
2544 spin_lock_irqsave(q->queue_lock, flags);
2545 attempt_back_merge(q, rq);
2546 spin_unlock_irqrestore(q->queue_lock, flags);
2547}
2548
2549EXPORT_SYMBOL(blk_attempt_remerge);
2550
2551/*
2552 * Non-locking blk_attempt_remerge variant.
2553 */
2554void __blk_attempt_remerge(request_queue_t *q, struct request *rq)
2555{
2556 attempt_back_merge(q, rq);
2557}
2558
2559EXPORT_SYMBOL(__blk_attempt_remerge);
2560
2561static int __make_request(request_queue_t *q, struct bio *bio)
2562{
2563 struct request *req, *freereq = NULL;
Jens Axboe4a534f92005-04-16 15:25:40 -07002564 int el_ret, rw, nr_sectors, cur_nr_sectors, barrier, err, sync;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002565 sector_t sector;
2566
2567 sector = bio->bi_sector;
2568 nr_sectors = bio_sectors(bio);
2569 cur_nr_sectors = bio_cur_sectors(bio);
2570
2571 rw = bio_data_dir(bio);
Jens Axboe4a534f92005-04-16 15:25:40 -07002572 sync = bio_sync(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002573
2574 /*
2575 * low level driver can indicate that it wants pages above a
2576 * certain limit bounced to low memory (ie for highmem, or even
2577 * ISA dma in theory)
2578 */
2579 blk_queue_bounce(q, &bio);
2580
2581 spin_lock_prefetch(q->queue_lock);
2582
2583 barrier = bio_barrier(bio);
2584 if (barrier && (q->ordered == QUEUE_ORDERED_NONE)) {
2585 err = -EOPNOTSUPP;
2586 goto end_io;
2587 }
2588
2589again:
2590 spin_lock_irq(q->queue_lock);
2591
2592 if (elv_queue_empty(q)) {
2593 blk_plug_device(q);
2594 goto get_rq;
2595 }
2596 if (barrier)
2597 goto get_rq;
2598
2599 el_ret = elv_merge(q, &req, bio);
2600 switch (el_ret) {
2601 case ELEVATOR_BACK_MERGE:
2602 BUG_ON(!rq_mergeable(req));
2603
2604 if (!q->back_merge_fn(q, req, bio))
2605 break;
2606
2607 req->biotail->bi_next = bio;
2608 req->biotail = bio;
2609 req->nr_sectors = req->hard_nr_sectors += nr_sectors;
2610 drive_stat_acct(req, nr_sectors, 0);
2611 if (!attempt_back_merge(q, req))
2612 elv_merged_request(q, req);
2613 goto out;
2614
2615 case ELEVATOR_FRONT_MERGE:
2616 BUG_ON(!rq_mergeable(req));
2617
2618 if (!q->front_merge_fn(q, req, bio))
2619 break;
2620
2621 bio->bi_next = req->bio;
2622 req->bio = bio;
2623
2624 /*
2625 * may not be valid. if the low level driver said
2626 * it didn't need a bounce buffer then it better
2627 * not touch req->buffer either...
2628 */
2629 req->buffer = bio_data(bio);
2630 req->current_nr_sectors = cur_nr_sectors;
2631 req->hard_cur_sectors = cur_nr_sectors;
2632 req->sector = req->hard_sector = sector;
2633 req->nr_sectors = req->hard_nr_sectors += nr_sectors;
2634 drive_stat_acct(req, nr_sectors, 0);
2635 if (!attempt_front_merge(q, req))
2636 elv_merged_request(q, req);
2637 goto out;
2638
2639 /*
2640 * elevator says don't/can't merge. get new request
2641 */
2642 case ELEVATOR_NO_MERGE:
2643 break;
2644
2645 default:
2646 printk("elevator returned crap (%d)\n", el_ret);
2647 BUG();
2648 }
2649
2650 /*
2651 * Grab a free request from the freelist - if that is empty, check
2652 * if we are doing read ahead and abort instead of blocking for
2653 * a free slot.
2654 */
2655get_rq:
2656 if (freereq) {
2657 req = freereq;
2658 freereq = NULL;
2659 } else {
2660 spin_unlock_irq(q->queue_lock);
2661 if ((freereq = get_request(q, rw, GFP_ATOMIC)) == NULL) {
2662 /*
2663 * READA bit set
2664 */
2665 err = -EWOULDBLOCK;
2666 if (bio_rw_ahead(bio))
2667 goto end_io;
2668
2669 freereq = get_request_wait(q, rw);
2670 }
2671 goto again;
2672 }
2673
2674 req->flags |= REQ_CMD;
2675
2676 /*
2677 * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST)
2678 */
2679 if (bio_rw_ahead(bio) || bio_failfast(bio))
2680 req->flags |= REQ_FAILFAST;
2681
2682 /*
2683 * REQ_BARRIER implies no merging, but lets make it explicit
2684 */
2685 if (barrier)
2686 req->flags |= (REQ_HARDBARRIER | REQ_NOMERGE);
2687
2688 req->errors = 0;
2689 req->hard_sector = req->sector = sector;
2690 req->hard_nr_sectors = req->nr_sectors = nr_sectors;
2691 req->current_nr_sectors = req->hard_cur_sectors = cur_nr_sectors;
2692 req->nr_phys_segments = bio_phys_segments(q, bio);
2693 req->nr_hw_segments = bio_hw_segments(q, bio);
2694 req->buffer = bio_data(bio); /* see ->buffer comment above */
2695 req->waiting = NULL;
2696 req->bio = req->biotail = bio;
2697 req->rq_disk = bio->bi_bdev->bd_disk;
2698 req->start_time = jiffies;
2699
2700 add_request(q, req);
2701out:
2702 if (freereq)
2703 __blk_put_request(q, freereq);
Jens Axboe4a534f92005-04-16 15:25:40 -07002704 if (sync)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002705 __generic_unplug_device(q);
2706
2707 spin_unlock_irq(q->queue_lock);
2708 return 0;
2709
2710end_io:
2711 bio_endio(bio, nr_sectors << 9, err);
2712 return 0;
2713}
2714
2715/*
2716 * If bio->bi_dev is a partition, remap the location
2717 */
2718static inline void blk_partition_remap(struct bio *bio)
2719{
2720 struct block_device *bdev = bio->bi_bdev;
2721
2722 if (bdev != bdev->bd_contains) {
2723 struct hd_struct *p = bdev->bd_part;
2724
2725 switch (bio->bi_rw) {
2726 case READ:
2727 p->read_sectors += bio_sectors(bio);
2728 p->reads++;
2729 break;
2730 case WRITE:
2731 p->write_sectors += bio_sectors(bio);
2732 p->writes++;
2733 break;
2734 }
2735 bio->bi_sector += p->start_sect;
2736 bio->bi_bdev = bdev->bd_contains;
2737 }
2738}
2739
2740void blk_finish_queue_drain(request_queue_t *q)
2741{
2742 struct request_list *rl = &q->rq;
2743 struct request *rq;
2744
2745 spin_lock_irq(q->queue_lock);
2746 clear_bit(QUEUE_FLAG_DRAIN, &q->queue_flags);
2747
2748 while (!list_empty(&q->drain_list)) {
2749 rq = list_entry_rq(q->drain_list.next);
2750
2751 list_del_init(&rq->queuelist);
2752 __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 1);
2753 }
2754
2755 spin_unlock_irq(q->queue_lock);
2756
2757 wake_up(&rl->wait[0]);
2758 wake_up(&rl->wait[1]);
2759 wake_up(&rl->drain);
2760}
2761
2762static int wait_drain(request_queue_t *q, struct request_list *rl, int dispatch)
2763{
2764 int wait = rl->count[READ] + rl->count[WRITE];
2765
2766 if (dispatch)
2767 wait += !list_empty(&q->queue_head);
2768
2769 return wait;
2770}
2771
2772/*
2773 * We rely on the fact that only requests allocated through blk_alloc_request()
2774 * have io scheduler private data structures associated with them. Any other
2775 * type of request (allocated on stack or through kmalloc()) should not go
2776 * to the io scheduler core, but be attached to the queue head instead.
2777 */
2778void blk_wait_queue_drained(request_queue_t *q, int wait_dispatch)
2779{
2780 struct request_list *rl = &q->rq;
2781 DEFINE_WAIT(wait);
2782
2783 spin_lock_irq(q->queue_lock);
2784 set_bit(QUEUE_FLAG_DRAIN, &q->queue_flags);
2785
2786 while (wait_drain(q, rl, wait_dispatch)) {
2787 prepare_to_wait(&rl->drain, &wait, TASK_UNINTERRUPTIBLE);
2788
2789 if (wait_drain(q, rl, wait_dispatch)) {
2790 __generic_unplug_device(q);
2791 spin_unlock_irq(q->queue_lock);
2792 io_schedule();
2793 spin_lock_irq(q->queue_lock);
2794 }
2795
2796 finish_wait(&rl->drain, &wait);
2797 }
2798
2799 spin_unlock_irq(q->queue_lock);
2800}
2801
2802/*
2803 * block waiting for the io scheduler being started again.
2804 */
2805static inline void block_wait_queue_running(request_queue_t *q)
2806{
2807 DEFINE_WAIT(wait);
2808
2809 while (test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags)) {
2810 struct request_list *rl = &q->rq;
2811
2812 prepare_to_wait_exclusive(&rl->drain, &wait,
2813 TASK_UNINTERRUPTIBLE);
2814
2815 /*
2816 * re-check the condition. avoids using prepare_to_wait()
2817 * in the fast path (queue is running)
2818 */
2819 if (test_bit(QUEUE_FLAG_DRAIN, &q->queue_flags))
2820 io_schedule();
2821
2822 finish_wait(&rl->drain, &wait);
2823 }
2824}
2825
2826static void handle_bad_sector(struct bio *bio)
2827{
2828 char b[BDEVNAME_SIZE];
2829
2830 printk(KERN_INFO "attempt to access beyond end of device\n");
2831 printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n",
2832 bdevname(bio->bi_bdev, b),
2833 bio->bi_rw,
2834 (unsigned long long)bio->bi_sector + bio_sectors(bio),
2835 (long long)(bio->bi_bdev->bd_inode->i_size >> 9));
2836
2837 set_bit(BIO_EOF, &bio->bi_flags);
2838}
2839
2840/**
2841 * generic_make_request: hand a buffer to its device driver for I/O
2842 * @bio: The bio describing the location in memory and on the device.
2843 *
2844 * generic_make_request() is used to make I/O requests of block
2845 * devices. It is passed a &struct bio, which describes the I/O that needs
2846 * to be done.
2847 *
2848 * generic_make_request() does not return any status. The
2849 * success/failure status of the request, along with notification of
2850 * completion, is delivered asynchronously through the bio->bi_end_io
2851 * function described (one day) else where.
2852 *
2853 * The caller of generic_make_request must make sure that bi_io_vec
2854 * are set to describe the memory buffer, and that bi_dev and bi_sector are
2855 * set to describe the device address, and the
2856 * bi_end_io and optionally bi_private are set to describe how
2857 * completion notification should be signaled.
2858 *
2859 * generic_make_request and the drivers it calls may use bi_next if this
2860 * bio happens to be merged with someone else, and may change bi_dev and
2861 * bi_sector for remaps as it sees fit. So the values of these fields
2862 * should NOT be depended on after the call to generic_make_request.
2863 */
2864void generic_make_request(struct bio *bio)
2865{
2866 request_queue_t *q;
2867 sector_t maxsector;
2868 int ret, nr_sectors = bio_sectors(bio);
2869
2870 might_sleep();
2871 /* Test device or partition size, when known. */
2872 maxsector = bio->bi_bdev->bd_inode->i_size >> 9;
2873 if (maxsector) {
2874 sector_t sector = bio->bi_sector;
2875
2876 if (maxsector < nr_sectors || maxsector - nr_sectors < sector) {
2877 /*
2878 * This may well happen - the kernel calls bread()
2879 * without checking the size of the device, e.g., when
2880 * mounting a device.
2881 */
2882 handle_bad_sector(bio);
2883 goto end_io;
2884 }
2885 }
2886
2887 /*
2888 * Resolve the mapping until finished. (drivers are
2889 * still free to implement/resolve their own stacking
2890 * by explicitly returning 0)
2891 *
2892 * NOTE: we don't repeat the blk_size check for each new device.
2893 * Stacking drivers are expected to know what they are doing.
2894 */
2895 do {
2896 char b[BDEVNAME_SIZE];
2897
2898 q = bdev_get_queue(bio->bi_bdev);
2899 if (!q) {
2900 printk(KERN_ERR
2901 "generic_make_request: Trying to access "
2902 "nonexistent block-device %s (%Lu)\n",
2903 bdevname(bio->bi_bdev, b),
2904 (long long) bio->bi_sector);
2905end_io:
2906 bio_endio(bio, bio->bi_size, -EIO);
2907 break;
2908 }
2909
2910 if (unlikely(bio_sectors(bio) > q->max_hw_sectors)) {
2911 printk("bio too big device %s (%u > %u)\n",
2912 bdevname(bio->bi_bdev, b),
2913 bio_sectors(bio),
2914 q->max_hw_sectors);
2915 goto end_io;
2916 }
2917
2918 if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))
2919 goto end_io;
2920
2921 block_wait_queue_running(q);
2922
2923 /*
2924 * If this device has partitions, remap block n
2925 * of partition p to block n+start(p) of the disk.
2926 */
2927 blk_partition_remap(bio);
2928
2929 ret = q->make_request_fn(q, bio);
2930 } while (ret);
2931}
2932
2933EXPORT_SYMBOL(generic_make_request);
2934
2935/**
2936 * submit_bio: submit a bio to the block device layer for I/O
2937 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
2938 * @bio: The &struct bio which describes the I/O
2939 *
2940 * submit_bio() is very similar in purpose to generic_make_request(), and
2941 * uses that function to do most of the work. Both are fairly rough
2942 * interfaces, @bio must be presetup and ready for I/O.
2943 *
2944 */
2945void submit_bio(int rw, struct bio *bio)
2946{
2947 int count = bio_sectors(bio);
2948
2949 BIO_BUG_ON(!bio->bi_size);
2950 BIO_BUG_ON(!bio->bi_io_vec);
2951 bio->bi_rw = rw;
2952 if (rw & WRITE)
2953 mod_page_state(pgpgout, count);
2954 else
2955 mod_page_state(pgpgin, count);
2956
2957 if (unlikely(block_dump)) {
2958 char b[BDEVNAME_SIZE];
2959 printk(KERN_DEBUG "%s(%d): %s block %Lu on %s\n",
2960 current->comm, current->pid,
2961 (rw & WRITE) ? "WRITE" : "READ",
2962 (unsigned long long)bio->bi_sector,
2963 bdevname(bio->bi_bdev,b));
2964 }
2965
2966 generic_make_request(bio);
2967}
2968
2969EXPORT_SYMBOL(submit_bio);
2970
2971void blk_recalc_rq_segments(struct request *rq)
2972{
2973 struct bio *bio, *prevbio = NULL;
2974 int nr_phys_segs, nr_hw_segs;
2975 unsigned int phys_size, hw_size;
2976 request_queue_t *q = rq->q;
2977
2978 if (!rq->bio)
2979 return;
2980
2981 phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0;
2982 rq_for_each_bio(bio, rq) {
2983 /* Force bio hw/phys segs to be recalculated. */
2984 bio->bi_flags &= ~(1 << BIO_SEG_VALID);
2985
2986 nr_phys_segs += bio_phys_segments(q, bio);
2987 nr_hw_segs += bio_hw_segments(q, bio);
2988 if (prevbio) {
2989 int pseg = phys_size + prevbio->bi_size + bio->bi_size;
2990 int hseg = hw_size + prevbio->bi_size + bio->bi_size;
2991
2992 if (blk_phys_contig_segment(q, prevbio, bio) &&
2993 pseg <= q->max_segment_size) {
2994 nr_phys_segs--;
2995 phys_size += prevbio->bi_size + bio->bi_size;
2996 } else
2997 phys_size = 0;
2998
2999 if (blk_hw_contig_segment(q, prevbio, bio) &&
3000 hseg <= q->max_segment_size) {
3001 nr_hw_segs--;
3002 hw_size += prevbio->bi_size + bio->bi_size;
3003 } else
3004 hw_size = 0;
3005 }
3006 prevbio = bio;
3007 }
3008
3009 rq->nr_phys_segments = nr_phys_segs;
3010 rq->nr_hw_segments = nr_hw_segs;
3011}
3012
3013void blk_recalc_rq_sectors(struct request *rq, int nsect)
3014{
3015 if (blk_fs_request(rq)) {
3016 rq->hard_sector += nsect;
3017 rq->hard_nr_sectors -= nsect;
3018
3019 /*
3020 * Move the I/O submission pointers ahead if required.
3021 */
3022 if ((rq->nr_sectors >= rq->hard_nr_sectors) &&
3023 (rq->sector <= rq->hard_sector)) {
3024 rq->sector = rq->hard_sector;
3025 rq->nr_sectors = rq->hard_nr_sectors;
3026 rq->hard_cur_sectors = bio_cur_sectors(rq->bio);
3027 rq->current_nr_sectors = rq->hard_cur_sectors;
3028 rq->buffer = bio_data(rq->bio);
3029 }
3030
3031 /*
3032 * if total number of sectors is less than the first segment
3033 * size, something has gone terribly wrong
3034 */
3035 if (rq->nr_sectors < rq->current_nr_sectors) {
3036 printk("blk: request botched\n");
3037 rq->nr_sectors = rq->current_nr_sectors;
3038 }
3039 }
3040}
3041
3042static int __end_that_request_first(struct request *req, int uptodate,
3043 int nr_bytes)
3044{
3045 int total_bytes, bio_nbytes, error, next_idx = 0;
3046 struct bio *bio;
3047
3048 /*
3049 * extend uptodate bool to allow < 0 value to be direct io error
3050 */
3051 error = 0;
3052 if (end_io_error(uptodate))
3053 error = !uptodate ? -EIO : uptodate;
3054
3055 /*
3056 * for a REQ_BLOCK_PC request, we want to carry any eventual
3057 * sense key with us all the way through
3058 */
3059 if (!blk_pc_request(req))
3060 req->errors = 0;
3061
3062 if (!uptodate) {
3063 if (blk_fs_request(req) && !(req->flags & REQ_QUIET))
3064 printk("end_request: I/O error, dev %s, sector %llu\n",
3065 req->rq_disk ? req->rq_disk->disk_name : "?",
3066 (unsigned long long)req->sector);
3067 }
3068
3069 total_bytes = bio_nbytes = 0;
3070 while ((bio = req->bio) != NULL) {
3071 int nbytes;
3072
3073 if (nr_bytes >= bio->bi_size) {
3074 req->bio = bio->bi_next;
3075 nbytes = bio->bi_size;
3076 bio_endio(bio, nbytes, error);
3077 next_idx = 0;
3078 bio_nbytes = 0;
3079 } else {
3080 int idx = bio->bi_idx + next_idx;
3081
3082 if (unlikely(bio->bi_idx >= bio->bi_vcnt)) {
3083 blk_dump_rq_flags(req, "__end_that");
3084 printk("%s: bio idx %d >= vcnt %d\n",
3085 __FUNCTION__,
3086 bio->bi_idx, bio->bi_vcnt);
3087 break;
3088 }
3089
3090 nbytes = bio_iovec_idx(bio, idx)->bv_len;
3091 BIO_BUG_ON(nbytes > bio->bi_size);
3092
3093 /*
3094 * not a complete bvec done
3095 */
3096 if (unlikely(nbytes > nr_bytes)) {
3097 bio_nbytes += nr_bytes;
3098 total_bytes += nr_bytes;
3099 break;
3100 }
3101
3102 /*
3103 * advance to the next vector
3104 */
3105 next_idx++;
3106 bio_nbytes += nbytes;
3107 }
3108
3109 total_bytes += nbytes;
3110 nr_bytes -= nbytes;
3111
3112 if ((bio = req->bio)) {
3113 /*
3114 * end more in this run, or just return 'not-done'
3115 */
3116 if (unlikely(nr_bytes <= 0))
3117 break;
3118 }
3119 }
3120
3121 /*
3122 * completely done
3123 */
3124 if (!req->bio)
3125 return 0;
3126
3127 /*
3128 * if the request wasn't completed, update state
3129 */
3130 if (bio_nbytes) {
3131 bio_endio(bio, bio_nbytes, error);
3132 bio->bi_idx += next_idx;
3133 bio_iovec(bio)->bv_offset += nr_bytes;
3134 bio_iovec(bio)->bv_len -= nr_bytes;
3135 }
3136
3137 blk_recalc_rq_sectors(req, total_bytes >> 9);
3138 blk_recalc_rq_segments(req);
3139 return 1;
3140}
3141
3142/**
3143 * end_that_request_first - end I/O on a request
3144 * @req: the request being processed
3145 * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error
3146 * @nr_sectors: number of sectors to end I/O on
3147 *
3148 * Description:
3149 * Ends I/O on a number of sectors attached to @req, and sets it up
3150 * for the next range of segments (if any) in the cluster.
3151 *
3152 * Return:
3153 * 0 - we are done with this request, call end_that_request_last()
3154 * 1 - still buffers pending for this request
3155 **/
3156int end_that_request_first(struct request *req, int uptodate, int nr_sectors)
3157{
3158 return __end_that_request_first(req, uptodate, nr_sectors << 9);
3159}
3160
3161EXPORT_SYMBOL(end_that_request_first);
3162
3163/**
3164 * end_that_request_chunk - end I/O on a request
3165 * @req: the request being processed
3166 * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error
3167 * @nr_bytes: number of bytes to complete
3168 *
3169 * Description:
3170 * Ends I/O on a number of bytes attached to @req, and sets it up
3171 * for the next range of segments (if any). Like end_that_request_first(),
3172 * but deals with bytes instead of sectors.
3173 *
3174 * Return:
3175 * 0 - we are done with this request, call end_that_request_last()
3176 * 1 - still buffers pending for this request
3177 **/
3178int end_that_request_chunk(struct request *req, int uptodate, int nr_bytes)
3179{
3180 return __end_that_request_first(req, uptodate, nr_bytes);
3181}
3182
3183EXPORT_SYMBOL(end_that_request_chunk);
3184
3185/*
3186 * queue lock must be held
3187 */
3188void end_that_request_last(struct request *req)
3189{
3190 struct gendisk *disk = req->rq_disk;
3191
3192 if (unlikely(laptop_mode) && blk_fs_request(req))
3193 laptop_io_completion();
3194
3195 if (disk && blk_fs_request(req)) {
3196 unsigned long duration = jiffies - req->start_time;
3197 switch (rq_data_dir(req)) {
3198 case WRITE:
3199 __disk_stat_inc(disk, writes);
3200 __disk_stat_add(disk, write_ticks, duration);
3201 break;
3202 case READ:
3203 __disk_stat_inc(disk, reads);
3204 __disk_stat_add(disk, read_ticks, duration);
3205 break;
3206 }
3207 disk_round_stats(disk);
3208 disk->in_flight--;
3209 }
3210 if (req->end_io)
3211 req->end_io(req);
3212 else
3213 __blk_put_request(req->q, req);
3214}
3215
3216EXPORT_SYMBOL(end_that_request_last);
3217
3218void end_request(struct request *req, int uptodate)
3219{
3220 if (!end_that_request_first(req, uptodate, req->hard_cur_sectors)) {
3221 add_disk_randomness(req->rq_disk);
3222 blkdev_dequeue_request(req);
3223 end_that_request_last(req);
3224 }
3225}
3226
3227EXPORT_SYMBOL(end_request);
3228
3229void blk_rq_bio_prep(request_queue_t *q, struct request *rq, struct bio *bio)
3230{
3231 /* first three bits are identical in rq->flags and bio->bi_rw */
3232 rq->flags |= (bio->bi_rw & 7);
3233
3234 rq->nr_phys_segments = bio_phys_segments(q, bio);
3235 rq->nr_hw_segments = bio_hw_segments(q, bio);
3236 rq->current_nr_sectors = bio_cur_sectors(bio);
3237 rq->hard_cur_sectors = rq->current_nr_sectors;
3238 rq->hard_nr_sectors = rq->nr_sectors = bio_sectors(bio);
3239 rq->buffer = bio_data(bio);
3240
3241 rq->bio = rq->biotail = bio;
3242}
3243
3244EXPORT_SYMBOL(blk_rq_bio_prep);
3245
3246int kblockd_schedule_work(struct work_struct *work)
3247{
3248 return queue_work(kblockd_workqueue, work);
3249}
3250
3251EXPORT_SYMBOL(kblockd_schedule_work);
3252
3253void kblockd_flush(void)
3254{
3255 flush_workqueue(kblockd_workqueue);
3256}
3257EXPORT_SYMBOL(kblockd_flush);
3258
3259int __init blk_dev_init(void)
3260{
3261 kblockd_workqueue = create_workqueue("kblockd");
3262 if (!kblockd_workqueue)
3263 panic("Failed to create kblockd\n");
3264
3265 request_cachep = kmem_cache_create("blkdev_requests",
3266 sizeof(struct request), 0, SLAB_PANIC, NULL, NULL);
3267
3268 requestq_cachep = kmem_cache_create("blkdev_queue",
3269 sizeof(request_queue_t), 0, SLAB_PANIC, NULL, NULL);
3270
3271 iocontext_cachep = kmem_cache_create("blkdev_ioc",
3272 sizeof(struct io_context), 0, SLAB_PANIC, NULL, NULL);
3273
3274 blk_max_low_pfn = max_low_pfn;
3275 blk_max_pfn = max_pfn;
3276
3277 return 0;
3278}
3279
3280/*
3281 * IO Context helper functions
3282 */
3283void put_io_context(struct io_context *ioc)
3284{
3285 if (ioc == NULL)
3286 return;
3287
3288 BUG_ON(atomic_read(&ioc->refcount) == 0);
3289
3290 if (atomic_dec_and_test(&ioc->refcount)) {
3291 if (ioc->aic && ioc->aic->dtor)
3292 ioc->aic->dtor(ioc->aic);
3293 if (ioc->cic && ioc->cic->dtor)
3294 ioc->cic->dtor(ioc->cic);
3295
3296 kmem_cache_free(iocontext_cachep, ioc);
3297 }
3298}
3299EXPORT_SYMBOL(put_io_context);
3300
3301/* Called by the exitting task */
3302void exit_io_context(void)
3303{
3304 unsigned long flags;
3305 struct io_context *ioc;
3306
3307 local_irq_save(flags);
3308 ioc = current->io_context;
3309 current->io_context = NULL;
3310 local_irq_restore(flags);
3311
3312 if (ioc->aic && ioc->aic->exit)
3313 ioc->aic->exit(ioc->aic);
3314 if (ioc->cic && ioc->cic->exit)
3315 ioc->cic->exit(ioc->cic);
3316
3317 put_io_context(ioc);
3318}
3319
3320/*
3321 * If the current task has no IO context then create one and initialise it.
3322 * If it does have a context, take a ref on it.
3323 *
3324 * This is always called in the context of the task which submitted the I/O.
3325 * But weird things happen, so we disable local interrupts to ensure exclusive
3326 * access to *current.
3327 */
3328struct io_context *get_io_context(int gfp_flags)
3329{
3330 struct task_struct *tsk = current;
3331 unsigned long flags;
3332 struct io_context *ret;
3333
3334 local_irq_save(flags);
3335 ret = tsk->io_context;
3336 if (ret)
3337 goto out;
3338
3339 local_irq_restore(flags);
3340
3341 ret = kmem_cache_alloc(iocontext_cachep, gfp_flags);
3342 if (ret) {
3343 atomic_set(&ret->refcount, 1);
3344 ret->pid = tsk->pid;
3345 ret->last_waited = jiffies; /* doesn't matter... */
3346 ret->nr_batch_requests = 0; /* because this is 0 */
3347 ret->aic = NULL;
3348 ret->cic = NULL;
3349 spin_lock_init(&ret->lock);
3350
3351 local_irq_save(flags);
3352
3353 /*
3354 * very unlikely, someone raced with us in setting up the task
3355 * io context. free new context and just grab a reference.
3356 */
3357 if (!tsk->io_context)
3358 tsk->io_context = ret;
3359 else {
3360 kmem_cache_free(iocontext_cachep, ret);
3361 ret = tsk->io_context;
3362 }
3363
3364out:
3365 atomic_inc(&ret->refcount);
3366 local_irq_restore(flags);
3367 }
3368
3369 return ret;
3370}
3371EXPORT_SYMBOL(get_io_context);
3372
3373void copy_io_context(struct io_context **pdst, struct io_context **psrc)
3374{
3375 struct io_context *src = *psrc;
3376 struct io_context *dst = *pdst;
3377
3378 if (src) {
3379 BUG_ON(atomic_read(&src->refcount) == 0);
3380 atomic_inc(&src->refcount);
3381 put_io_context(dst);
3382 *pdst = src;
3383 }
3384}
3385EXPORT_SYMBOL(copy_io_context);
3386
3387void swap_io_context(struct io_context **ioc1, struct io_context **ioc2)
3388{
3389 struct io_context *temp;
3390 temp = *ioc1;
3391 *ioc1 = *ioc2;
3392 *ioc2 = temp;
3393}
3394EXPORT_SYMBOL(swap_io_context);
3395
3396/*
3397 * sysfs parts below
3398 */
3399struct queue_sysfs_entry {
3400 struct attribute attr;
3401 ssize_t (*show)(struct request_queue *, char *);
3402 ssize_t (*store)(struct request_queue *, const char *, size_t);
3403};
3404
3405static ssize_t
3406queue_var_show(unsigned int var, char *page)
3407{
3408 return sprintf(page, "%d\n", var);
3409}
3410
3411static ssize_t
3412queue_var_store(unsigned long *var, const char *page, size_t count)
3413{
3414 char *p = (char *) page;
3415
3416 *var = simple_strtoul(p, &p, 10);
3417 return count;
3418}
3419
3420static ssize_t queue_requests_show(struct request_queue *q, char *page)
3421{
3422 return queue_var_show(q->nr_requests, (page));
3423}
3424
3425static ssize_t
3426queue_requests_store(struct request_queue *q, const char *page, size_t count)
3427{
3428 struct request_list *rl = &q->rq;
3429
3430 int ret = queue_var_store(&q->nr_requests, page, count);
3431 if (q->nr_requests < BLKDEV_MIN_RQ)
3432 q->nr_requests = BLKDEV_MIN_RQ;
3433 blk_queue_congestion_threshold(q);
3434
3435 if (rl->count[READ] >= queue_congestion_on_threshold(q))
3436 set_queue_congested(q, READ);
3437 else if (rl->count[READ] < queue_congestion_off_threshold(q))
3438 clear_queue_congested(q, READ);
3439
3440 if (rl->count[WRITE] >= queue_congestion_on_threshold(q))
3441 set_queue_congested(q, WRITE);
3442 else if (rl->count[WRITE] < queue_congestion_off_threshold(q))
3443 clear_queue_congested(q, WRITE);
3444
3445 if (rl->count[READ] >= q->nr_requests) {
3446 blk_set_queue_full(q, READ);
3447 } else if (rl->count[READ]+1 <= q->nr_requests) {
3448 blk_clear_queue_full(q, READ);
3449 wake_up(&rl->wait[READ]);
3450 }
3451
3452 if (rl->count[WRITE] >= q->nr_requests) {
3453 blk_set_queue_full(q, WRITE);
3454 } else if (rl->count[WRITE]+1 <= q->nr_requests) {
3455 blk_clear_queue_full(q, WRITE);
3456 wake_up(&rl->wait[WRITE]);
3457 }
3458 return ret;
3459}
3460
3461static ssize_t queue_ra_show(struct request_queue *q, char *page)
3462{
3463 int ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10);
3464
3465 return queue_var_show(ra_kb, (page));
3466}
3467
3468static ssize_t
3469queue_ra_store(struct request_queue *q, const char *page, size_t count)
3470{
3471 unsigned long ra_kb;
3472 ssize_t ret = queue_var_store(&ra_kb, page, count);
3473
3474 spin_lock_irq(q->queue_lock);
3475 if (ra_kb > (q->max_sectors >> 1))
3476 ra_kb = (q->max_sectors >> 1);
3477
3478 q->backing_dev_info.ra_pages = ra_kb >> (PAGE_CACHE_SHIFT - 10);
3479 spin_unlock_irq(q->queue_lock);
3480
3481 return ret;
3482}
3483
3484static ssize_t queue_max_sectors_show(struct request_queue *q, char *page)
3485{
3486 int max_sectors_kb = q->max_sectors >> 1;
3487
3488 return queue_var_show(max_sectors_kb, (page));
3489}
3490
3491static ssize_t
3492queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
3493{
3494 unsigned long max_sectors_kb,
3495 max_hw_sectors_kb = q->max_hw_sectors >> 1,
3496 page_kb = 1 << (PAGE_CACHE_SHIFT - 10);
3497 ssize_t ret = queue_var_store(&max_sectors_kb, page, count);
3498 int ra_kb;
3499
3500 if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
3501 return -EINVAL;
3502 /*
3503 * Take the queue lock to update the readahead and max_sectors
3504 * values synchronously:
3505 */
3506 spin_lock_irq(q->queue_lock);
3507 /*
3508 * Trim readahead window as well, if necessary:
3509 */
3510 ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10);
3511 if (ra_kb > max_sectors_kb)
3512 q->backing_dev_info.ra_pages =
3513 max_sectors_kb >> (PAGE_CACHE_SHIFT - 10);
3514
3515 q->max_sectors = max_sectors_kb << 1;
3516 spin_unlock_irq(q->queue_lock);
3517
3518 return ret;
3519}
3520
3521static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page)
3522{
3523 int max_hw_sectors_kb = q->max_hw_sectors >> 1;
3524
3525 return queue_var_show(max_hw_sectors_kb, (page));
3526}
3527
3528
3529static struct queue_sysfs_entry queue_requests_entry = {
3530 .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
3531 .show = queue_requests_show,
3532 .store = queue_requests_store,
3533};
3534
3535static struct queue_sysfs_entry queue_ra_entry = {
3536 .attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR },
3537 .show = queue_ra_show,
3538 .store = queue_ra_store,
3539};
3540
3541static struct queue_sysfs_entry queue_max_sectors_entry = {
3542 .attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR },
3543 .show = queue_max_sectors_show,
3544 .store = queue_max_sectors_store,
3545};
3546
3547static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
3548 .attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO },
3549 .show = queue_max_hw_sectors_show,
3550};
3551
3552static struct queue_sysfs_entry queue_iosched_entry = {
3553 .attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR },
3554 .show = elv_iosched_show,
3555 .store = elv_iosched_store,
3556};
3557
3558static struct attribute *default_attrs[] = {
3559 &queue_requests_entry.attr,
3560 &queue_ra_entry.attr,
3561 &queue_max_hw_sectors_entry.attr,
3562 &queue_max_sectors_entry.attr,
3563 &queue_iosched_entry.attr,
3564 NULL,
3565};
3566
3567#define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
3568
3569static ssize_t
3570queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
3571{
3572 struct queue_sysfs_entry *entry = to_queue(attr);
3573 struct request_queue *q;
3574
3575 q = container_of(kobj, struct request_queue, kobj);
3576 if (!entry->show)
3577 return 0;
3578
3579 return entry->show(q, page);
3580}
3581
3582static ssize_t
3583queue_attr_store(struct kobject *kobj, struct attribute *attr,
3584 const char *page, size_t length)
3585{
3586 struct queue_sysfs_entry *entry = to_queue(attr);
3587 struct request_queue *q;
3588
3589 q = container_of(kobj, struct request_queue, kobj);
3590 if (!entry->store)
3591 return -EINVAL;
3592
3593 return entry->store(q, page, length);
3594}
3595
3596static struct sysfs_ops queue_sysfs_ops = {
3597 .show = queue_attr_show,
3598 .store = queue_attr_store,
3599};
3600
3601struct kobj_type queue_ktype = {
3602 .sysfs_ops = &queue_sysfs_ops,
3603 .default_attrs = default_attrs,
3604};
3605
3606int blk_register_queue(struct gendisk *disk)
3607{
3608 int ret;
3609
3610 request_queue_t *q = disk->queue;
3611
3612 if (!q || !q->request_fn)
3613 return -ENXIO;
3614
3615 q->kobj.parent = kobject_get(&disk->kobj);
3616 if (!q->kobj.parent)
3617 return -EBUSY;
3618
3619 snprintf(q->kobj.name, KOBJ_NAME_LEN, "%s", "queue");
3620 q->kobj.ktype = &queue_ktype;
3621
3622 ret = kobject_register(&q->kobj);
3623 if (ret < 0)
3624 return ret;
3625
3626 ret = elv_register_queue(q);
3627 if (ret) {
3628 kobject_unregister(&q->kobj);
3629 return ret;
3630 }
3631
3632 return 0;
3633}
3634
3635void blk_unregister_queue(struct gendisk *disk)
3636{
3637 request_queue_t *q = disk->queue;
3638
3639 if (q && q->request_fn) {
3640 elv_unregister_queue(q);
3641
3642 kobject_unregister(&q->kobj);
3643 kobject_put(&disk->kobj);
3644 }
3645}