blob: e5041a02e21f5c7ee4e93597ef95967643380462 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 * Copyright (C) 1991, 1992 Linus Torvalds
3 * Copyright (C) 1994, Karl Keyte: Added support for disk statistics
4 * Elevator latency, (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
5 * Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de>
6 * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au> - July2000
7 * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001
8 */
9
10/*
11 * This handles all read/write requests to block devices
12 */
13#include <linux/config.h>
14#include <linux/kernel.h>
15#include <linux/module.h>
16#include <linux/backing-dev.h>
17#include <linux/bio.h>
18#include <linux/blkdev.h>
19#include <linux/highmem.h>
20#include <linux/mm.h>
21#include <linux/kernel_stat.h>
22#include <linux/string.h>
23#include <linux/init.h>
24#include <linux/bootmem.h> /* for max_pfn/max_low_pfn */
25#include <linux/completion.h>
26#include <linux/slab.h>
27#include <linux/swap.h>
28#include <linux/writeback.h>
Jens Axboeff856ba2006-01-09 16:02:34 +010029#include <linux/interrupt.h>
30#include <linux/cpu.h>
Jens Axboe2056a782006-03-23 20:00:26 +010031#include <linux/blktrace_api.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070032
33/*
34 * for max sense size
35 */
36#include <scsi/scsi_cmnd.h>
37
38static void blk_unplug_work(void *data);
39static void blk_unplug_timeout(unsigned long data);
Adrian Bunk93d17d32005-06-25 14:59:10 -070040static void drive_stat_acct(struct request *rq, int nr_sectors, int new_io);
Tejun Heo52d9e672006-01-06 09:49:58 +010041static void init_request_from_bio(struct request *req, struct bio *bio);
42static int __make_request(request_queue_t *q, struct bio *bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -070043
44/*
45 * For the allocated request tables
46 */
47static kmem_cache_t *request_cachep;
48
49/*
50 * For queue allocation
51 */
52static kmem_cache_t *requestq_cachep;
53
54/*
55 * For io context allocations
56 */
57static kmem_cache_t *iocontext_cachep;
58
59static wait_queue_head_t congestion_wqh[2] = {
60 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
61 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
62 };
63
64/*
65 * Controlling structure to kblockd
66 */
Jens Axboeff856ba2006-01-09 16:02:34 +010067static struct workqueue_struct *kblockd_workqueue;
Linus Torvalds1da177e2005-04-16 15:20:36 -070068
69unsigned long blk_max_low_pfn, blk_max_pfn;
70
71EXPORT_SYMBOL(blk_max_low_pfn);
72EXPORT_SYMBOL(blk_max_pfn);
73
Jens Axboeff856ba2006-01-09 16:02:34 +010074static DEFINE_PER_CPU(struct list_head, blk_cpu_done);
75
Linus Torvalds1da177e2005-04-16 15:20:36 -070076/* Amount of time in which a process may batch requests */
77#define BLK_BATCH_TIME (HZ/50UL)
78
79/* Number of requests a "batching" process may submit */
80#define BLK_BATCH_REQ 32
81
82/*
83 * Return the threshold (number of used requests) at which the queue is
84 * considered to be congested. It include a little hysteresis to keep the
85 * context switch rate down.
86 */
87static inline int queue_congestion_on_threshold(struct request_queue *q)
88{
89 return q->nr_congestion_on;
90}
91
92/*
93 * The threshold at which a queue is considered to be uncongested
94 */
95static inline int queue_congestion_off_threshold(struct request_queue *q)
96{
97 return q->nr_congestion_off;
98}
99
100static void blk_queue_congestion_threshold(struct request_queue *q)
101{
102 int nr;
103
104 nr = q->nr_requests - (q->nr_requests / 8) + 1;
105 if (nr > q->nr_requests)
106 nr = q->nr_requests;
107 q->nr_congestion_on = nr;
108
109 nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1;
110 if (nr < 1)
111 nr = 1;
112 q->nr_congestion_off = nr;
113}
114
115/*
116 * A queue has just exitted congestion. Note this in the global counter of
117 * congested queues, and wake up anyone who was waiting for requests to be
118 * put back.
119 */
120static void clear_queue_congested(request_queue_t *q, int rw)
121{
122 enum bdi_state bit;
123 wait_queue_head_t *wqh = &congestion_wqh[rw];
124
125 bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
126 clear_bit(bit, &q->backing_dev_info.state);
127 smp_mb__after_clear_bit();
128 if (waitqueue_active(wqh))
129 wake_up(wqh);
130}
131
132/*
133 * A queue has just entered congestion. Flag that in the queue's VM-visible
134 * state flags and increment the global gounter of congested queues.
135 */
136static void set_queue_congested(request_queue_t *q, int rw)
137{
138 enum bdi_state bit;
139
140 bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
141 set_bit(bit, &q->backing_dev_info.state);
142}
143
144/**
145 * blk_get_backing_dev_info - get the address of a queue's backing_dev_info
146 * @bdev: device
147 *
148 * Locates the passed device's request queue and returns the address of its
149 * backing_dev_info
150 *
151 * Will return NULL if the request queue cannot be located.
152 */
153struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev)
154{
155 struct backing_dev_info *ret = NULL;
156 request_queue_t *q = bdev_get_queue(bdev);
157
158 if (q)
159 ret = &q->backing_dev_info;
160 return ret;
161}
162
163EXPORT_SYMBOL(blk_get_backing_dev_info);
164
165void blk_queue_activity_fn(request_queue_t *q, activity_fn *fn, void *data)
166{
167 q->activity_fn = fn;
168 q->activity_data = data;
169}
170
171EXPORT_SYMBOL(blk_queue_activity_fn);
172
173/**
174 * blk_queue_prep_rq - set a prepare_request function for queue
175 * @q: queue
176 * @pfn: prepare_request function
177 *
178 * It's possible for a queue to register a prepare_request callback which
179 * is invoked before the request is handed to the request_fn. The goal of
180 * the function is to prepare a request for I/O, it can be used to build a
181 * cdb from the request data for instance.
182 *
183 */
184void blk_queue_prep_rq(request_queue_t *q, prep_rq_fn *pfn)
185{
186 q->prep_rq_fn = pfn;
187}
188
189EXPORT_SYMBOL(blk_queue_prep_rq);
190
191/**
192 * blk_queue_merge_bvec - set a merge_bvec function for queue
193 * @q: queue
194 * @mbfn: merge_bvec_fn
195 *
196 * Usually queues have static limitations on the max sectors or segments that
197 * we can put in a request. Stacking drivers may have some settings that
198 * are dynamic, and thus we have to query the queue whether it is ok to
199 * add a new bio_vec to a bio at a given offset or not. If the block device
200 * has such limitations, it needs to register a merge_bvec_fn to control
201 * the size of bio's sent to it. Note that a block device *must* allow a
202 * single page to be added to an empty bio. The block device driver may want
203 * to use the bio_split() function to deal with these bio's. By default
204 * no merge_bvec_fn is defined for a queue, and only the fixed limits are
205 * honored.
206 */
207void blk_queue_merge_bvec(request_queue_t *q, merge_bvec_fn *mbfn)
208{
209 q->merge_bvec_fn = mbfn;
210}
211
212EXPORT_SYMBOL(blk_queue_merge_bvec);
213
Jens Axboeff856ba2006-01-09 16:02:34 +0100214void blk_queue_softirq_done(request_queue_t *q, softirq_done_fn *fn)
215{
216 q->softirq_done_fn = fn;
217}
218
219EXPORT_SYMBOL(blk_queue_softirq_done);
220
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221/**
222 * blk_queue_make_request - define an alternate make_request function for a device
223 * @q: the request queue for the device to be affected
224 * @mfn: the alternate make_request function
225 *
226 * Description:
227 * The normal way for &struct bios to be passed to a device
228 * driver is for them to be collected into requests on a request
229 * queue, and then to allow the device driver to select requests
230 * off that queue when it is ready. This works well for many block
231 * devices. However some block devices (typically virtual devices
232 * such as md or lvm) do not benefit from the processing on the
233 * request queue, and are served best by having the requests passed
234 * directly to them. This can be achieved by providing a function
235 * to blk_queue_make_request().
236 *
237 * Caveat:
238 * The driver that does this *must* be able to deal appropriately
239 * with buffers in "highmemory". This can be accomplished by either calling
240 * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling
241 * blk_queue_bounce() to create a buffer in normal memory.
242 **/
243void blk_queue_make_request(request_queue_t * q, make_request_fn * mfn)
244{
245 /*
246 * set defaults
247 */
248 q->nr_requests = BLKDEV_MAX_RQ;
Stuart McLaren309c0a12005-09-06 15:17:47 -0700249 blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS);
250 blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251 q->make_request_fn = mfn;
252 q->backing_dev_info.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
253 q->backing_dev_info.state = 0;
254 q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY;
Mike Christiedefd94b2005-12-05 02:37:06 -0600255 blk_queue_max_sectors(q, SAFE_MAX_SECTORS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256 blk_queue_hardsect_size(q, 512);
257 blk_queue_dma_alignment(q, 511);
258 blk_queue_congestion_threshold(q);
259 q->nr_batching = BLK_BATCH_REQ;
260
261 q->unplug_thresh = 4; /* hmm */
262 q->unplug_delay = (3 * HZ) / 1000; /* 3 milliseconds */
263 if (q->unplug_delay == 0)
264 q->unplug_delay = 1;
265
266 INIT_WORK(&q->unplug_work, blk_unplug_work, q);
267
268 q->unplug_timer.function = blk_unplug_timeout;
269 q->unplug_timer.data = (unsigned long)q;
270
271 /*
272 * by default assume old behaviour and bounce for any highmem page
273 */
274 blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH);
275
276 blk_queue_activity_fn(q, NULL, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700277}
278
279EXPORT_SYMBOL(blk_queue_make_request);
280
281static inline void rq_init(request_queue_t *q, struct request *rq)
282{
283 INIT_LIST_HEAD(&rq->queuelist);
Jens Axboeff856ba2006-01-09 16:02:34 +0100284 INIT_LIST_HEAD(&rq->donelist);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285
286 rq->errors = 0;
287 rq->rq_status = RQ_ACTIVE;
288 rq->bio = rq->biotail = NULL;
Jens Axboe22e2c502005-06-27 10:55:12 +0200289 rq->ioprio = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290 rq->buffer = NULL;
291 rq->ref_count = 1;
292 rq->q = q;
293 rq->waiting = NULL;
294 rq->special = NULL;
295 rq->data_len = 0;
296 rq->data = NULL;
Mike Christie df46b9a2005-06-20 14:04:44 +0200297 rq->nr_phys_segments = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298 rq->sense = NULL;
299 rq->end_io = NULL;
300 rq->end_io_data = NULL;
Jens Axboeff856ba2006-01-09 16:02:34 +0100301 rq->completion_data = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302}
303
304/**
305 * blk_queue_ordered - does this queue support ordered writes
Tejun Heo797e7db2006-01-06 09:51:03 +0100306 * @q: the request queue
307 * @ordered: one of QUEUE_ORDERED_*
Jens Axboefddfdea2006-01-31 15:24:34 +0100308 * @prepare_flush_fn: rq setup helper for cache flush ordered writes
Linus Torvalds1da177e2005-04-16 15:20:36 -0700309 *
310 * Description:
311 * For journalled file systems, doing ordered writes on a commit
312 * block instead of explicitly doing wait_on_buffer (which is bad
313 * for performance) can be a big win. Block drivers supporting this
314 * feature should call this function and indicate so.
315 *
316 **/
Tejun Heo797e7db2006-01-06 09:51:03 +0100317int blk_queue_ordered(request_queue_t *q, unsigned ordered,
318 prepare_flush_fn *prepare_flush_fn)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319{
Tejun Heo797e7db2006-01-06 09:51:03 +0100320 if (ordered & (QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_POSTFLUSH) &&
321 prepare_flush_fn == NULL) {
322 printk(KERN_ERR "blk_queue_ordered: prepare_flush_fn required\n");
323 return -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324 }
Tejun Heo797e7db2006-01-06 09:51:03 +0100325
326 if (ordered != QUEUE_ORDERED_NONE &&
327 ordered != QUEUE_ORDERED_DRAIN &&
328 ordered != QUEUE_ORDERED_DRAIN_FLUSH &&
329 ordered != QUEUE_ORDERED_DRAIN_FUA &&
330 ordered != QUEUE_ORDERED_TAG &&
331 ordered != QUEUE_ORDERED_TAG_FLUSH &&
332 ordered != QUEUE_ORDERED_TAG_FUA) {
333 printk(KERN_ERR "blk_queue_ordered: bad value %d\n", ordered);
334 return -EINVAL;
335 }
336
Tetsuo Takata60481b12006-01-24 10:34:36 +0100337 q->ordered = ordered;
Tejun Heo797e7db2006-01-06 09:51:03 +0100338 q->next_ordered = ordered;
339 q->prepare_flush_fn = prepare_flush_fn;
340
341 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342}
343
344EXPORT_SYMBOL(blk_queue_ordered);
345
346/**
347 * blk_queue_issue_flush_fn - set function for issuing a flush
348 * @q: the request queue
349 * @iff: the function to be called issuing the flush
350 *
351 * Description:
352 * If a driver supports issuing a flush command, the support is notified
353 * to the block layer by defining it through this call.
354 *
355 **/
356void blk_queue_issue_flush_fn(request_queue_t *q, issue_flush_fn *iff)
357{
358 q->issue_flush_fn = iff;
359}
360
361EXPORT_SYMBOL(blk_queue_issue_flush_fn);
362
363/*
364 * Cache flushing for ordered writes handling
365 */
Tejun Heo797e7db2006-01-06 09:51:03 +0100366inline unsigned blk_ordered_cur_seq(request_queue_t *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367{
Tejun Heo797e7db2006-01-06 09:51:03 +0100368 if (!q->ordseq)
369 return 0;
370 return 1 << ffz(q->ordseq);
371}
372
373unsigned blk_ordered_req_seq(struct request *rq)
374{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375 request_queue_t *q = rq->q;
376
Tejun Heo797e7db2006-01-06 09:51:03 +0100377 BUG_ON(q->ordseq == 0);
Tejun Heo8922e162005-10-20 16:23:44 +0200378
Tejun Heo797e7db2006-01-06 09:51:03 +0100379 if (rq == &q->pre_flush_rq)
380 return QUEUE_ORDSEQ_PREFLUSH;
381 if (rq == &q->bar_rq)
382 return QUEUE_ORDSEQ_BAR;
383 if (rq == &q->post_flush_rq)
384 return QUEUE_ORDSEQ_POSTFLUSH;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385
Tejun Heo797e7db2006-01-06 09:51:03 +0100386 if ((rq->flags & REQ_ORDERED_COLOR) ==
387 (q->orig_bar_rq->flags & REQ_ORDERED_COLOR))
388 return QUEUE_ORDSEQ_DRAIN;
389 else
390 return QUEUE_ORDSEQ_DONE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391}
392
Tejun Heo797e7db2006-01-06 09:51:03 +0100393void blk_ordered_complete_seq(request_queue_t *q, unsigned seq, int error)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394{
Tejun Heo797e7db2006-01-06 09:51:03 +0100395 struct request *rq;
396 int uptodate;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397
Tejun Heo797e7db2006-01-06 09:51:03 +0100398 if (error && !q->orderr)
399 q->orderr = error;
Tejun Heo8922e162005-10-20 16:23:44 +0200400
Tejun Heo797e7db2006-01-06 09:51:03 +0100401 BUG_ON(q->ordseq & seq);
402 q->ordseq |= seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403
Tejun Heo797e7db2006-01-06 09:51:03 +0100404 if (blk_ordered_cur_seq(q) != QUEUE_ORDSEQ_DONE)
405 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406
407 /*
Tejun Heo797e7db2006-01-06 09:51:03 +0100408 * Okay, sequence complete.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409 */
Tejun Heo797e7db2006-01-06 09:51:03 +0100410 rq = q->orig_bar_rq;
411 uptodate = q->orderr ? q->orderr : 1;
412
413 q->ordseq = 0;
414
415 end_that_request_first(rq, uptodate, rq->hard_nr_sectors);
416 end_that_request_last(rq, uptodate);
417}
418
419static void pre_flush_end_io(struct request *rq, int error)
420{
421 elv_completed_request(rq->q, rq);
422 blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_PREFLUSH, error);
423}
424
425static void bar_end_io(struct request *rq, int error)
426{
427 elv_completed_request(rq->q, rq);
428 blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_BAR, error);
429}
430
431static void post_flush_end_io(struct request *rq, int error)
432{
433 elv_completed_request(rq->q, rq);
434 blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_POSTFLUSH, error);
435}
436
437static void queue_flush(request_queue_t *q, unsigned which)
438{
439 struct request *rq;
440 rq_end_io_fn *end_io;
441
442 if (which == QUEUE_ORDERED_PREFLUSH) {
443 rq = &q->pre_flush_rq;
444 end_io = pre_flush_end_io;
445 } else {
446 rq = &q->post_flush_rq;
447 end_io = post_flush_end_io;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448 }
449
Tejun Heo797e7db2006-01-06 09:51:03 +0100450 rq_init(q, rq);
451 rq->flags = REQ_HARDBARRIER;
452 rq->elevator_private = NULL;
453 rq->rq_disk = q->bar_rq.rq_disk;
454 rq->rl = NULL;
455 rq->end_io = end_io;
456 q->prepare_flush_fn(q, rq);
457
Tejun Heo30e96562006-02-08 01:01:31 -0800458 elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
Tejun Heo797e7db2006-01-06 09:51:03 +0100459}
460
461static inline struct request *start_ordered(request_queue_t *q,
462 struct request *rq)
463{
464 q->bi_size = 0;
465 q->orderr = 0;
466 q->ordered = q->next_ordered;
467 q->ordseq |= QUEUE_ORDSEQ_STARTED;
468
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469 /*
Tejun Heo797e7db2006-01-06 09:51:03 +0100470 * Prep proxy barrier request.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471 */
Tejun Heo797e7db2006-01-06 09:51:03 +0100472 blkdev_dequeue_request(rq);
473 q->orig_bar_rq = rq;
474 rq = &q->bar_rq;
475 rq_init(q, rq);
476 rq->flags = bio_data_dir(q->orig_bar_rq->bio);
477 rq->flags |= q->ordered & QUEUE_ORDERED_FUA ? REQ_FUA : 0;
478 rq->elevator_private = NULL;
479 rq->rl = NULL;
480 init_request_from_bio(rq, q->orig_bar_rq->bio);
481 rq->end_io = bar_end_io;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700482
Tejun Heo797e7db2006-01-06 09:51:03 +0100483 /*
484 * Queue ordered sequence. As we stack them at the head, we
485 * need to queue in reverse order. Note that we rely on that
486 * no fs request uses ELEVATOR_INSERT_FRONT and thus no fs
487 * request gets inbetween ordered sequence.
488 */
489 if (q->ordered & QUEUE_ORDERED_POSTFLUSH)
490 queue_flush(q, QUEUE_ORDERED_POSTFLUSH);
491 else
492 q->ordseq |= QUEUE_ORDSEQ_POSTFLUSH;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493
Tejun Heo30e96562006-02-08 01:01:31 -0800494 elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
Tejun Heo797e7db2006-01-06 09:51:03 +0100495
496 if (q->ordered & QUEUE_ORDERED_PREFLUSH) {
497 queue_flush(q, QUEUE_ORDERED_PREFLUSH);
498 rq = &q->pre_flush_rq;
499 } else
500 q->ordseq |= QUEUE_ORDSEQ_PREFLUSH;
501
502 if ((q->ordered & QUEUE_ORDERED_TAG) || q->in_flight == 0)
503 q->ordseq |= QUEUE_ORDSEQ_DRAIN;
504 else
505 rq = NULL;
506
507 return rq;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508}
509
Tejun Heo797e7db2006-01-06 09:51:03 +0100510int blk_do_ordered(request_queue_t *q, struct request **rqp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511{
Jens Axboe9a7a67a2006-02-04 23:27:38 -0800512 struct request *rq = *rqp;
Tejun Heo797e7db2006-01-06 09:51:03 +0100513 int is_barrier = blk_fs_request(rq) && blk_barrier_rq(rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700514
Tejun Heo797e7db2006-01-06 09:51:03 +0100515 if (!q->ordseq) {
516 if (!is_barrier)
517 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700518
Tejun Heo797e7db2006-01-06 09:51:03 +0100519 if (q->next_ordered != QUEUE_ORDERED_NONE) {
520 *rqp = start_ordered(q, rq);
521 return 1;
522 } else {
523 /*
524 * This can happen when the queue switches to
525 * ORDERED_NONE while this request is on it.
526 */
527 blkdev_dequeue_request(rq);
528 end_that_request_first(rq, -EOPNOTSUPP,
529 rq->hard_nr_sectors);
530 end_that_request_last(rq, -EOPNOTSUPP);
531 *rqp = NULL;
532 return 0;
533 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700534 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535
Jens Axboe9a7a67a2006-02-04 23:27:38 -0800536 /*
537 * Ordered sequence in progress
538 */
539
540 /* Special requests are not subject to ordering rules. */
541 if (!blk_fs_request(rq) &&
542 rq != &q->pre_flush_rq && rq != &q->post_flush_rq)
543 return 1;
544
Tejun Heo797e7db2006-01-06 09:51:03 +0100545 if (q->ordered & QUEUE_ORDERED_TAG) {
Jens Axboe9a7a67a2006-02-04 23:27:38 -0800546 /* Ordered by tag. Blocking the next barrier is enough. */
Tejun Heo797e7db2006-01-06 09:51:03 +0100547 if (is_barrier && rq != &q->bar_rq)
548 *rqp = NULL;
Jens Axboe9a7a67a2006-02-04 23:27:38 -0800549 } else {
550 /* Ordered by draining. Wait for turn. */
551 WARN_ON(blk_ordered_req_seq(rq) < blk_ordered_cur_seq(q));
552 if (blk_ordered_req_seq(rq) > blk_ordered_cur_seq(q))
553 *rqp = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554 }
555
556 return 1;
557}
558
Tejun Heo797e7db2006-01-06 09:51:03 +0100559static int flush_dry_bio_endio(struct bio *bio, unsigned int bytes, int error)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700560{
Tejun Heo797e7db2006-01-06 09:51:03 +0100561 request_queue_t *q = bio->bi_private;
562 struct bio_vec *bvec;
563 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700564
Tejun Heo797e7db2006-01-06 09:51:03 +0100565 /*
566 * This is dry run, restore bio_sector and size. We'll finish
567 * this request again with the original bi_end_io after an
568 * error occurs or post flush is complete.
569 */
570 q->bi_size += bytes;
571
572 if (bio->bi_size)
573 return 1;
574
575 /* Rewind bvec's */
576 bio->bi_idx = 0;
577 bio_for_each_segment(bvec, bio, i) {
578 bvec->bv_len += bvec->bv_offset;
579 bvec->bv_offset = 0;
580 }
581
582 /* Reset bio */
583 set_bit(BIO_UPTODATE, &bio->bi_flags);
584 bio->bi_size = q->bi_size;
585 bio->bi_sector -= (q->bi_size >> 9);
586 q->bi_size = 0;
587
588 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589}
Tejun Heo797e7db2006-01-06 09:51:03 +0100590
591static inline int ordered_bio_endio(struct request *rq, struct bio *bio,
592 unsigned int nbytes, int error)
593{
594 request_queue_t *q = rq->q;
595 bio_end_io_t *endio;
596 void *private;
597
598 if (&q->bar_rq != rq)
599 return 0;
600
601 /*
602 * Okay, this is the barrier request in progress, dry finish it.
603 */
604 if (error && !q->orderr)
605 q->orderr = error;
606
607 endio = bio->bi_end_io;
608 private = bio->bi_private;
609 bio->bi_end_io = flush_dry_bio_endio;
610 bio->bi_private = q;
611
612 bio_endio(bio, nbytes, error);
613
614 bio->bi_end_io = endio;
615 bio->bi_private = private;
616
617 return 1;
618}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700619
620/**
621 * blk_queue_bounce_limit - set bounce buffer limit for queue
622 * @q: the request queue for the device
623 * @dma_addr: bus address limit
624 *
625 * Description:
626 * Different hardware can have different requirements as to what pages
627 * it can do I/O directly to. A low level driver can call
628 * blk_queue_bounce_limit to have lower memory pages allocated as bounce
Andi Kleen5ee1af92006-03-08 17:57:26 -0800629 * buffers for doing I/O to pages residing above @page.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700630 **/
631void blk_queue_bounce_limit(request_queue_t *q, u64 dma_addr)
632{
633 unsigned long bounce_pfn = dma_addr >> PAGE_SHIFT;
Andi Kleen5ee1af92006-03-08 17:57:26 -0800634 int dma = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700635
Andi Kleen5ee1af92006-03-08 17:57:26 -0800636 q->bounce_gfp = GFP_NOIO;
637#if BITS_PER_LONG == 64
638 /* Assume anything <= 4GB can be handled by IOMMU.
639 Actually some IOMMUs can handle everything, but I don't
640 know of a way to test this here. */
641 if (bounce_pfn < (0xffffffff>>PAGE_SHIFT))
642 dma = 1;
643 q->bounce_pfn = max_low_pfn;
644#else
645 if (bounce_pfn < blk_max_low_pfn)
646 dma = 1;
647 q->bounce_pfn = bounce_pfn;
648#endif
649 if (dma) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700650 init_emergency_isa_pool();
651 q->bounce_gfp = GFP_NOIO | GFP_DMA;
Andi Kleen5ee1af92006-03-08 17:57:26 -0800652 q->bounce_pfn = bounce_pfn;
653 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700654}
655
656EXPORT_SYMBOL(blk_queue_bounce_limit);
657
658/**
659 * blk_queue_max_sectors - set max sectors for a request for this queue
660 * @q: the request queue for the device
661 * @max_sectors: max sectors in the usual 512b unit
662 *
663 * Description:
664 * Enables a low level driver to set an upper limit on the size of
665 * received requests.
666 **/
Jens Axboe2cb2e142006-01-17 09:04:32 +0100667void blk_queue_max_sectors(request_queue_t *q, unsigned int max_sectors)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668{
669 if ((max_sectors << 9) < PAGE_CACHE_SIZE) {
670 max_sectors = 1 << (PAGE_CACHE_SHIFT - 9);
671 printk("%s: set to minimum %d\n", __FUNCTION__, max_sectors);
672 }
673
Mike Christiedefd94b2005-12-05 02:37:06 -0600674 if (BLK_DEF_MAX_SECTORS > max_sectors)
675 q->max_hw_sectors = q->max_sectors = max_sectors;
676 else {
677 q->max_sectors = BLK_DEF_MAX_SECTORS;
678 q->max_hw_sectors = max_sectors;
679 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680}
681
682EXPORT_SYMBOL(blk_queue_max_sectors);
683
684/**
685 * blk_queue_max_phys_segments - set max phys segments for a request for this queue
686 * @q: the request queue for the device
687 * @max_segments: max number of segments
688 *
689 * Description:
690 * Enables a low level driver to set an upper limit on the number of
691 * physical data segments in a request. This would be the largest sized
692 * scatter list the driver could handle.
693 **/
694void blk_queue_max_phys_segments(request_queue_t *q, unsigned short max_segments)
695{
696 if (!max_segments) {
697 max_segments = 1;
698 printk("%s: set to minimum %d\n", __FUNCTION__, max_segments);
699 }
700
701 q->max_phys_segments = max_segments;
702}
703
704EXPORT_SYMBOL(blk_queue_max_phys_segments);
705
706/**
707 * blk_queue_max_hw_segments - set max hw segments for a request for this queue
708 * @q: the request queue for the device
709 * @max_segments: max number of segments
710 *
711 * Description:
712 * Enables a low level driver to set an upper limit on the number of
713 * hw data segments in a request. This would be the largest number of
714 * address/length pairs the host adapter can actually give as once
715 * to the device.
716 **/
717void blk_queue_max_hw_segments(request_queue_t *q, unsigned short max_segments)
718{
719 if (!max_segments) {
720 max_segments = 1;
721 printk("%s: set to minimum %d\n", __FUNCTION__, max_segments);
722 }
723
724 q->max_hw_segments = max_segments;
725}
726
727EXPORT_SYMBOL(blk_queue_max_hw_segments);
728
729/**
730 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
731 * @q: the request queue for the device
732 * @max_size: max size of segment in bytes
733 *
734 * Description:
735 * Enables a low level driver to set an upper limit on the size of a
736 * coalesced segment
737 **/
738void blk_queue_max_segment_size(request_queue_t *q, unsigned int max_size)
739{
740 if (max_size < PAGE_CACHE_SIZE) {
741 max_size = PAGE_CACHE_SIZE;
742 printk("%s: set to minimum %d\n", __FUNCTION__, max_size);
743 }
744
745 q->max_segment_size = max_size;
746}
747
748EXPORT_SYMBOL(blk_queue_max_segment_size);
749
750/**
751 * blk_queue_hardsect_size - set hardware sector size for the queue
752 * @q: the request queue for the device
753 * @size: the hardware sector size, in bytes
754 *
755 * Description:
756 * This should typically be set to the lowest possible sector size
757 * that the hardware can operate on (possible without reverting to
758 * even internal read-modify-write operations). Usually the default
759 * of 512 covers most hardware.
760 **/
761void blk_queue_hardsect_size(request_queue_t *q, unsigned short size)
762{
763 q->hardsect_size = size;
764}
765
766EXPORT_SYMBOL(blk_queue_hardsect_size);
767
768/*
769 * Returns the minimum that is _not_ zero, unless both are zero.
770 */
771#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
772
773/**
774 * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
775 * @t: the stacking driver (top)
776 * @b: the underlying device (bottom)
777 **/
778void blk_queue_stack_limits(request_queue_t *t, request_queue_t *b)
779{
780 /* zero is "infinity" */
Mike Christiedefd94b2005-12-05 02:37:06 -0600781 t->max_sectors = min_not_zero(t->max_sectors,b->max_sectors);
782 t->max_hw_sectors = min_not_zero(t->max_hw_sectors,b->max_hw_sectors);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700783
784 t->max_phys_segments = min(t->max_phys_segments,b->max_phys_segments);
785 t->max_hw_segments = min(t->max_hw_segments,b->max_hw_segments);
786 t->max_segment_size = min(t->max_segment_size,b->max_segment_size);
787 t->hardsect_size = max(t->hardsect_size,b->hardsect_size);
NeilBrown89e5c8b2006-03-27 01:18:02 -0800788 if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags))
789 clear_bit(QUEUE_FLAG_CLUSTER, &t->queue_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700790}
791
792EXPORT_SYMBOL(blk_queue_stack_limits);
793
794/**
795 * blk_queue_segment_boundary - set boundary rules for segment merging
796 * @q: the request queue for the device
797 * @mask: the memory boundary mask
798 **/
799void blk_queue_segment_boundary(request_queue_t *q, unsigned long mask)
800{
801 if (mask < PAGE_CACHE_SIZE - 1) {
802 mask = PAGE_CACHE_SIZE - 1;
803 printk("%s: set to minimum %lx\n", __FUNCTION__, mask);
804 }
805
806 q->seg_boundary_mask = mask;
807}
808
809EXPORT_SYMBOL(blk_queue_segment_boundary);
810
811/**
812 * blk_queue_dma_alignment - set dma length and memory alignment
813 * @q: the request queue for the device
814 * @mask: alignment mask
815 *
816 * description:
817 * set required memory and length aligment for direct dma transactions.
818 * this is used when buiding direct io requests for the queue.
819 *
820 **/
821void blk_queue_dma_alignment(request_queue_t *q, int mask)
822{
823 q->dma_alignment = mask;
824}
825
826EXPORT_SYMBOL(blk_queue_dma_alignment);
827
828/**
829 * blk_queue_find_tag - find a request by its tag and queue
Linus Torvalds1da177e2005-04-16 15:20:36 -0700830 * @q: The request queue for the device
831 * @tag: The tag of the request
832 *
833 * Notes:
834 * Should be used when a device returns a tag and you want to match
835 * it with a request.
836 *
837 * no locks need be held.
838 **/
839struct request *blk_queue_find_tag(request_queue_t *q, int tag)
840{
841 struct blk_queue_tag *bqt = q->queue_tags;
842
Tejun Heoba025082005-08-05 13:28:11 -0700843 if (unlikely(bqt == NULL || tag >= bqt->real_max_depth))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700844 return NULL;
845
846 return bqt->tag_index[tag];
847}
848
849EXPORT_SYMBOL(blk_queue_find_tag);
850
851/**
852 * __blk_queue_free_tags - release tag maintenance info
853 * @q: the request queue for the device
854 *
855 * Notes:
856 * blk_cleanup_queue() will take care of calling this function, if tagging
857 * has been used. So there's no need to call this directly.
858 **/
859static void __blk_queue_free_tags(request_queue_t *q)
860{
861 struct blk_queue_tag *bqt = q->queue_tags;
862
863 if (!bqt)
864 return;
865
866 if (atomic_dec_and_test(&bqt->refcnt)) {
867 BUG_ON(bqt->busy);
868 BUG_ON(!list_empty(&bqt->busy_list));
869
870 kfree(bqt->tag_index);
871 bqt->tag_index = NULL;
872
873 kfree(bqt->tag_map);
874 bqt->tag_map = NULL;
875
876 kfree(bqt);
877 }
878
879 q->queue_tags = NULL;
880 q->queue_flags &= ~(1 << QUEUE_FLAG_QUEUED);
881}
882
883/**
884 * blk_queue_free_tags - release tag maintenance info
885 * @q: the request queue for the device
886 *
887 * Notes:
888 * This is used to disabled tagged queuing to a device, yet leave
889 * queue in function.
890 **/
891void blk_queue_free_tags(request_queue_t *q)
892{
893 clear_bit(QUEUE_FLAG_QUEUED, &q->queue_flags);
894}
895
896EXPORT_SYMBOL(blk_queue_free_tags);
897
898static int
899init_tag_map(request_queue_t *q, struct blk_queue_tag *tags, int depth)
900{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700901 struct request **tag_index;
902 unsigned long *tag_map;
Tejun Heofa72b902005-06-23 00:08:49 -0700903 int nr_ulongs;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700904
905 if (depth > q->nr_requests * 2) {
906 depth = q->nr_requests * 2;
907 printk(KERN_ERR "%s: adjusted depth to %d\n",
908 __FUNCTION__, depth);
909 }
910
Jens Axboef68110f2006-03-08 13:31:44 +0100911 tag_index = kzalloc(depth * sizeof(struct request *), GFP_ATOMIC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700912 if (!tag_index)
913 goto fail;
914
Tejun Heof7d37d02005-06-23 00:08:50 -0700915 nr_ulongs = ALIGN(depth, BITS_PER_LONG) / BITS_PER_LONG;
Jens Axboef68110f2006-03-08 13:31:44 +0100916 tag_map = kzalloc(nr_ulongs * sizeof(unsigned long), GFP_ATOMIC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700917 if (!tag_map)
918 goto fail;
919
Tejun Heoba025082005-08-05 13:28:11 -0700920 tags->real_max_depth = depth;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921 tags->max_depth = depth;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700922 tags->tag_index = tag_index;
923 tags->tag_map = tag_map;
924
Linus Torvalds1da177e2005-04-16 15:20:36 -0700925 return 0;
926fail:
927 kfree(tag_index);
928 return -ENOMEM;
929}
930
931/**
932 * blk_queue_init_tags - initialize the queue tag info
933 * @q: the request queue for the device
934 * @depth: the maximum queue depth supported
935 * @tags: the tag to use
936 **/
937int blk_queue_init_tags(request_queue_t *q, int depth,
938 struct blk_queue_tag *tags)
939{
940 int rc;
941
942 BUG_ON(tags && q->queue_tags && tags != q->queue_tags);
943
944 if (!tags && !q->queue_tags) {
945 tags = kmalloc(sizeof(struct blk_queue_tag), GFP_ATOMIC);
946 if (!tags)
947 goto fail;
948
949 if (init_tag_map(q, tags, depth))
950 goto fail;
951
952 INIT_LIST_HEAD(&tags->busy_list);
953 tags->busy = 0;
954 atomic_set(&tags->refcnt, 1);
955 } else if (q->queue_tags) {
956 if ((rc = blk_queue_resize_tags(q, depth)))
957 return rc;
958 set_bit(QUEUE_FLAG_QUEUED, &q->queue_flags);
959 return 0;
960 } else
961 atomic_inc(&tags->refcnt);
962
963 /*
964 * assign it, all done
965 */
966 q->queue_tags = tags;
967 q->queue_flags |= (1 << QUEUE_FLAG_QUEUED);
968 return 0;
969fail:
970 kfree(tags);
971 return -ENOMEM;
972}
973
974EXPORT_SYMBOL(blk_queue_init_tags);
975
976/**
977 * blk_queue_resize_tags - change the queueing depth
978 * @q: the request queue for the device
979 * @new_depth: the new max command queueing depth
980 *
981 * Notes:
982 * Must be called with the queue lock held.
983 **/
984int blk_queue_resize_tags(request_queue_t *q, int new_depth)
985{
986 struct blk_queue_tag *bqt = q->queue_tags;
987 struct request **tag_index;
988 unsigned long *tag_map;
Tejun Heofa72b902005-06-23 00:08:49 -0700989 int max_depth, nr_ulongs;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700990
991 if (!bqt)
992 return -ENXIO;
993
994 /*
Tejun Heoba025082005-08-05 13:28:11 -0700995 * if we already have large enough real_max_depth. just
996 * adjust max_depth. *NOTE* as requests with tag value
997 * between new_depth and real_max_depth can be in-flight, tag
998 * map can not be shrunk blindly here.
999 */
1000 if (new_depth <= bqt->real_max_depth) {
1001 bqt->max_depth = new_depth;
1002 return 0;
1003 }
1004
1005 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001006 * save the old state info, so we can copy it back
1007 */
1008 tag_index = bqt->tag_index;
1009 tag_map = bqt->tag_map;
Tejun Heoba025082005-08-05 13:28:11 -07001010 max_depth = bqt->real_max_depth;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001011
1012 if (init_tag_map(q, bqt, new_depth))
1013 return -ENOMEM;
1014
1015 memcpy(bqt->tag_index, tag_index, max_depth * sizeof(struct request *));
Tejun Heof7d37d02005-06-23 00:08:50 -07001016 nr_ulongs = ALIGN(max_depth, BITS_PER_LONG) / BITS_PER_LONG;
Tejun Heofa72b902005-06-23 00:08:49 -07001017 memcpy(bqt->tag_map, tag_map, nr_ulongs * sizeof(unsigned long));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001018
1019 kfree(tag_index);
1020 kfree(tag_map);
1021 return 0;
1022}
1023
1024EXPORT_SYMBOL(blk_queue_resize_tags);
1025
1026/**
1027 * blk_queue_end_tag - end tag operations for a request
1028 * @q: the request queue for the device
1029 * @rq: the request that has completed
1030 *
1031 * Description:
1032 * Typically called when end_that_request_first() returns 0, meaning
1033 * all transfers have been done for a request. It's important to call
1034 * this function before end_that_request_last(), as that will put the
1035 * request back on the free list thus corrupting the internal tag list.
1036 *
1037 * Notes:
1038 * queue lock must be held.
1039 **/
1040void blk_queue_end_tag(request_queue_t *q, struct request *rq)
1041{
1042 struct blk_queue_tag *bqt = q->queue_tags;
1043 int tag = rq->tag;
1044
1045 BUG_ON(tag == -1);
1046
Tejun Heoba025082005-08-05 13:28:11 -07001047 if (unlikely(tag >= bqt->real_max_depth))
Tejun Heo040c9282005-06-23 00:08:51 -07001048 /*
1049 * This can happen after tag depth has been reduced.
1050 * FIXME: how about a warning or info message here?
1051 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001052 return;
1053
1054 if (unlikely(!__test_and_clear_bit(tag, bqt->tag_map))) {
Tejun Heo040c9282005-06-23 00:08:51 -07001055 printk(KERN_ERR "%s: attempt to clear non-busy tag (%d)\n",
1056 __FUNCTION__, tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001057 return;
1058 }
1059
1060 list_del_init(&rq->queuelist);
1061 rq->flags &= ~REQ_QUEUED;
1062 rq->tag = -1;
1063
1064 if (unlikely(bqt->tag_index[tag] == NULL))
Tejun Heo040c9282005-06-23 00:08:51 -07001065 printk(KERN_ERR "%s: tag %d is missing\n",
1066 __FUNCTION__, tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001067
1068 bqt->tag_index[tag] = NULL;
1069 bqt->busy--;
1070}
1071
1072EXPORT_SYMBOL(blk_queue_end_tag);
1073
1074/**
1075 * blk_queue_start_tag - find a free tag and assign it
1076 * @q: the request queue for the device
1077 * @rq: the block request that needs tagging
1078 *
1079 * Description:
1080 * This can either be used as a stand-alone helper, or possibly be
1081 * assigned as the queue &prep_rq_fn (in which case &struct request
1082 * automagically gets a tag assigned). Note that this function
1083 * assumes that any type of request can be queued! if this is not
1084 * true for your device, you must check the request type before
1085 * calling this function. The request will also be removed from
1086 * the request queue, so it's the drivers responsibility to readd
1087 * it if it should need to be restarted for some reason.
1088 *
1089 * Notes:
1090 * queue lock must be held.
1091 **/
1092int blk_queue_start_tag(request_queue_t *q, struct request *rq)
1093{
1094 struct blk_queue_tag *bqt = q->queue_tags;
Tejun Heo2bf0fda2005-06-23 00:08:48 -07001095 int tag;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001096
1097 if (unlikely((rq->flags & REQ_QUEUED))) {
1098 printk(KERN_ERR
Tejun Heo040c9282005-06-23 00:08:51 -07001099 "%s: request %p for device [%s] already tagged %d",
1100 __FUNCTION__, rq,
1101 rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001102 BUG();
1103 }
1104
Tejun Heo2bf0fda2005-06-23 00:08:48 -07001105 tag = find_first_zero_bit(bqt->tag_map, bqt->max_depth);
1106 if (tag >= bqt->max_depth)
1107 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001108
Linus Torvalds1da177e2005-04-16 15:20:36 -07001109 __set_bit(tag, bqt->tag_map);
1110
1111 rq->flags |= REQ_QUEUED;
1112 rq->tag = tag;
1113 bqt->tag_index[tag] = rq;
1114 blkdev_dequeue_request(rq);
1115 list_add(&rq->queuelist, &bqt->busy_list);
1116 bqt->busy++;
1117 return 0;
1118}
1119
1120EXPORT_SYMBOL(blk_queue_start_tag);
1121
1122/**
1123 * blk_queue_invalidate_tags - invalidate all pending tags
1124 * @q: the request queue for the device
1125 *
1126 * Description:
1127 * Hardware conditions may dictate a need to stop all pending requests.
1128 * In this case, we will safely clear the block side of the tag queue and
1129 * readd all requests to the request queue in the right order.
1130 *
1131 * Notes:
1132 * queue lock must be held.
1133 **/
1134void blk_queue_invalidate_tags(request_queue_t *q)
1135{
1136 struct blk_queue_tag *bqt = q->queue_tags;
1137 struct list_head *tmp, *n;
1138 struct request *rq;
1139
1140 list_for_each_safe(tmp, n, &bqt->busy_list) {
1141 rq = list_entry_rq(tmp);
1142
1143 if (rq->tag == -1) {
Tejun Heo040c9282005-06-23 00:08:51 -07001144 printk(KERN_ERR
1145 "%s: bad tag found on list\n", __FUNCTION__);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001146 list_del_init(&rq->queuelist);
1147 rq->flags &= ~REQ_QUEUED;
1148 } else
1149 blk_queue_end_tag(q, rq);
1150
1151 rq->flags &= ~REQ_STARTED;
1152 __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0);
1153 }
1154}
1155
1156EXPORT_SYMBOL(blk_queue_invalidate_tags);
1157
Arjan van de Ven64100092006-01-06 09:46:02 +01001158static const char * const rq_flags[] = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001159 "REQ_RW",
1160 "REQ_FAILFAST",
Tejun Heo8922e162005-10-20 16:23:44 +02001161 "REQ_SORTED",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001162 "REQ_SOFTBARRIER",
1163 "REQ_HARDBARRIER",
Tejun Heo797e7db2006-01-06 09:51:03 +01001164 "REQ_FUA",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001165 "REQ_CMD",
1166 "REQ_NOMERGE",
1167 "REQ_STARTED",
1168 "REQ_DONTPREP",
1169 "REQ_QUEUED",
Tejun Heocb98fc82005-10-28 08:29:39 +02001170 "REQ_ELVPRIV",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001171 "REQ_PC",
1172 "REQ_BLOCK_PC",
1173 "REQ_SENSE",
1174 "REQ_FAILED",
1175 "REQ_QUIET",
1176 "REQ_SPECIAL",
1177 "REQ_DRIVE_CMD",
1178 "REQ_DRIVE_TASK",
1179 "REQ_DRIVE_TASKFILE",
1180 "REQ_PREEMPT",
1181 "REQ_PM_SUSPEND",
1182 "REQ_PM_RESUME",
1183 "REQ_PM_SHUTDOWN",
Tejun Heo797e7db2006-01-06 09:51:03 +01001184 "REQ_ORDERED_COLOR",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001185};
1186
1187void blk_dump_rq_flags(struct request *rq, char *msg)
1188{
1189 int bit;
1190
1191 printk("%s: dev %s: flags = ", msg,
1192 rq->rq_disk ? rq->rq_disk->disk_name : "?");
1193 bit = 0;
1194 do {
1195 if (rq->flags & (1 << bit))
1196 printk("%s ", rq_flags[bit]);
1197 bit++;
1198 } while (bit < __REQ_NR_BITS);
1199
1200 printk("\nsector %llu, nr/cnr %lu/%u\n", (unsigned long long)rq->sector,
1201 rq->nr_sectors,
1202 rq->current_nr_sectors);
1203 printk("bio %p, biotail %p, buffer %p, data %p, len %u\n", rq->bio, rq->biotail, rq->buffer, rq->data, rq->data_len);
1204
1205 if (rq->flags & (REQ_BLOCK_PC | REQ_PC)) {
1206 printk("cdb: ");
1207 for (bit = 0; bit < sizeof(rq->cmd); bit++)
1208 printk("%02x ", rq->cmd[bit]);
1209 printk("\n");
1210 }
1211}
1212
1213EXPORT_SYMBOL(blk_dump_rq_flags);
1214
1215void blk_recount_segments(request_queue_t *q, struct bio *bio)
1216{
1217 struct bio_vec *bv, *bvprv = NULL;
1218 int i, nr_phys_segs, nr_hw_segs, seg_size, hw_seg_size, cluster;
1219 int high, highprv = 1;
1220
1221 if (unlikely(!bio->bi_io_vec))
1222 return;
1223
1224 cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
1225 hw_seg_size = seg_size = nr_phys_segs = nr_hw_segs = 0;
1226 bio_for_each_segment(bv, bio, i) {
1227 /*
1228 * the trick here is making sure that a high page is never
1229 * considered part of another segment, since that might
1230 * change with the bounce page.
1231 */
1232 high = page_to_pfn(bv->bv_page) >= q->bounce_pfn;
1233 if (high || highprv)
1234 goto new_hw_segment;
1235 if (cluster) {
1236 if (seg_size + bv->bv_len > q->max_segment_size)
1237 goto new_segment;
1238 if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv))
1239 goto new_segment;
1240 if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv))
1241 goto new_segment;
1242 if (BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len))
1243 goto new_hw_segment;
1244
1245 seg_size += bv->bv_len;
1246 hw_seg_size += bv->bv_len;
1247 bvprv = bv;
1248 continue;
1249 }
1250new_segment:
1251 if (BIOVEC_VIRT_MERGEABLE(bvprv, bv) &&
1252 !BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len)) {
1253 hw_seg_size += bv->bv_len;
1254 } else {
1255new_hw_segment:
1256 if (hw_seg_size > bio->bi_hw_front_size)
1257 bio->bi_hw_front_size = hw_seg_size;
1258 hw_seg_size = BIOVEC_VIRT_START_SIZE(bv) + bv->bv_len;
1259 nr_hw_segs++;
1260 }
1261
1262 nr_phys_segs++;
1263 bvprv = bv;
1264 seg_size = bv->bv_len;
1265 highprv = high;
1266 }
1267 if (hw_seg_size > bio->bi_hw_back_size)
1268 bio->bi_hw_back_size = hw_seg_size;
1269 if (nr_hw_segs == 1 && hw_seg_size > bio->bi_hw_front_size)
1270 bio->bi_hw_front_size = hw_seg_size;
1271 bio->bi_phys_segments = nr_phys_segs;
1272 bio->bi_hw_segments = nr_hw_segs;
1273 bio->bi_flags |= (1 << BIO_SEG_VALID);
1274}
1275
1276
Adrian Bunk93d17d32005-06-25 14:59:10 -07001277static int blk_phys_contig_segment(request_queue_t *q, struct bio *bio,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001278 struct bio *nxt)
1279{
1280 if (!(q->queue_flags & (1 << QUEUE_FLAG_CLUSTER)))
1281 return 0;
1282
1283 if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)))
1284 return 0;
1285 if (bio->bi_size + nxt->bi_size > q->max_segment_size)
1286 return 0;
1287
1288 /*
1289 * bio and nxt are contigous in memory, check if the queue allows
1290 * these two to be merged into one
1291 */
1292 if (BIO_SEG_BOUNDARY(q, bio, nxt))
1293 return 1;
1294
1295 return 0;
1296}
1297
Adrian Bunk93d17d32005-06-25 14:59:10 -07001298static int blk_hw_contig_segment(request_queue_t *q, struct bio *bio,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001299 struct bio *nxt)
1300{
1301 if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
1302 blk_recount_segments(q, bio);
1303 if (unlikely(!bio_flagged(nxt, BIO_SEG_VALID)))
1304 blk_recount_segments(q, nxt);
1305 if (!BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)) ||
1306 BIOVEC_VIRT_OVERSIZE(bio->bi_hw_front_size + bio->bi_hw_back_size))
1307 return 0;
1308 if (bio->bi_size + nxt->bi_size > q->max_segment_size)
1309 return 0;
1310
1311 return 1;
1312}
1313
Linus Torvalds1da177e2005-04-16 15:20:36 -07001314/*
1315 * map a request to scatterlist, return number of sg entries setup. Caller
1316 * must make sure sg can hold rq->nr_phys_segments entries
1317 */
1318int blk_rq_map_sg(request_queue_t *q, struct request *rq, struct scatterlist *sg)
1319{
1320 struct bio_vec *bvec, *bvprv;
1321 struct bio *bio;
1322 int nsegs, i, cluster;
1323
1324 nsegs = 0;
1325 cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
1326
1327 /*
1328 * for each bio in rq
1329 */
1330 bvprv = NULL;
1331 rq_for_each_bio(bio, rq) {
1332 /*
1333 * for each segment in bio
1334 */
1335 bio_for_each_segment(bvec, bio, i) {
1336 int nbytes = bvec->bv_len;
1337
1338 if (bvprv && cluster) {
1339 if (sg[nsegs - 1].length + nbytes > q->max_segment_size)
1340 goto new_segment;
1341
1342 if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec))
1343 goto new_segment;
1344 if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec))
1345 goto new_segment;
1346
1347 sg[nsegs - 1].length += nbytes;
1348 } else {
1349new_segment:
1350 memset(&sg[nsegs],0,sizeof(struct scatterlist));
1351 sg[nsegs].page = bvec->bv_page;
1352 sg[nsegs].length = nbytes;
1353 sg[nsegs].offset = bvec->bv_offset;
1354
1355 nsegs++;
1356 }
1357 bvprv = bvec;
1358 } /* segments in bio */
1359 } /* bios in rq */
1360
1361 return nsegs;
1362}
1363
1364EXPORT_SYMBOL(blk_rq_map_sg);
1365
1366/*
1367 * the standard queue merge functions, can be overridden with device
1368 * specific ones if so desired
1369 */
1370
1371static inline int ll_new_mergeable(request_queue_t *q,
1372 struct request *req,
1373 struct bio *bio)
1374{
1375 int nr_phys_segs = bio_phys_segments(q, bio);
1376
1377 if (req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) {
1378 req->flags |= REQ_NOMERGE;
1379 if (req == q->last_merge)
1380 q->last_merge = NULL;
1381 return 0;
1382 }
1383
1384 /*
1385 * A hw segment is just getting larger, bump just the phys
1386 * counter.
1387 */
1388 req->nr_phys_segments += nr_phys_segs;
1389 return 1;
1390}
1391
1392static inline int ll_new_hw_segment(request_queue_t *q,
1393 struct request *req,
1394 struct bio *bio)
1395{
1396 int nr_hw_segs = bio_hw_segments(q, bio);
1397 int nr_phys_segs = bio_phys_segments(q, bio);
1398
1399 if (req->nr_hw_segments + nr_hw_segs > q->max_hw_segments
1400 || req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) {
1401 req->flags |= REQ_NOMERGE;
1402 if (req == q->last_merge)
1403 q->last_merge = NULL;
1404 return 0;
1405 }
1406
1407 /*
1408 * This will form the start of a new hw segment. Bump both
1409 * counters.
1410 */
1411 req->nr_hw_segments += nr_hw_segs;
1412 req->nr_phys_segments += nr_phys_segs;
1413 return 1;
1414}
1415
1416static int ll_back_merge_fn(request_queue_t *q, struct request *req,
1417 struct bio *bio)
1418{
Mike Christiedefd94b2005-12-05 02:37:06 -06001419 unsigned short max_sectors;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001420 int len;
1421
Mike Christiedefd94b2005-12-05 02:37:06 -06001422 if (unlikely(blk_pc_request(req)))
1423 max_sectors = q->max_hw_sectors;
1424 else
1425 max_sectors = q->max_sectors;
1426
1427 if (req->nr_sectors + bio_sectors(bio) > max_sectors) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001428 req->flags |= REQ_NOMERGE;
1429 if (req == q->last_merge)
1430 q->last_merge = NULL;
1431 return 0;
1432 }
1433 if (unlikely(!bio_flagged(req->biotail, BIO_SEG_VALID)))
1434 blk_recount_segments(q, req->biotail);
1435 if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
1436 blk_recount_segments(q, bio);
1437 len = req->biotail->bi_hw_back_size + bio->bi_hw_front_size;
1438 if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req->biotail), __BVEC_START(bio)) &&
1439 !BIOVEC_VIRT_OVERSIZE(len)) {
1440 int mergeable = ll_new_mergeable(q, req, bio);
1441
1442 if (mergeable) {
1443 if (req->nr_hw_segments == 1)
1444 req->bio->bi_hw_front_size = len;
1445 if (bio->bi_hw_segments == 1)
1446 bio->bi_hw_back_size = len;
1447 }
1448 return mergeable;
1449 }
1450
1451 return ll_new_hw_segment(q, req, bio);
1452}
1453
1454static int ll_front_merge_fn(request_queue_t *q, struct request *req,
1455 struct bio *bio)
1456{
Mike Christiedefd94b2005-12-05 02:37:06 -06001457 unsigned short max_sectors;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001458 int len;
1459
Mike Christiedefd94b2005-12-05 02:37:06 -06001460 if (unlikely(blk_pc_request(req)))
1461 max_sectors = q->max_hw_sectors;
1462 else
1463 max_sectors = q->max_sectors;
1464
1465
1466 if (req->nr_sectors + bio_sectors(bio) > max_sectors) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001467 req->flags |= REQ_NOMERGE;
1468 if (req == q->last_merge)
1469 q->last_merge = NULL;
1470 return 0;
1471 }
1472 len = bio->bi_hw_back_size + req->bio->bi_hw_front_size;
1473 if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
1474 blk_recount_segments(q, bio);
1475 if (unlikely(!bio_flagged(req->bio, BIO_SEG_VALID)))
1476 blk_recount_segments(q, req->bio);
1477 if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(req->bio)) &&
1478 !BIOVEC_VIRT_OVERSIZE(len)) {
1479 int mergeable = ll_new_mergeable(q, req, bio);
1480
1481 if (mergeable) {
1482 if (bio->bi_hw_segments == 1)
1483 bio->bi_hw_front_size = len;
1484 if (req->nr_hw_segments == 1)
1485 req->biotail->bi_hw_back_size = len;
1486 }
1487 return mergeable;
1488 }
1489
1490 return ll_new_hw_segment(q, req, bio);
1491}
1492
1493static int ll_merge_requests_fn(request_queue_t *q, struct request *req,
1494 struct request *next)
1495{
Nikita Danilovdfa1a552005-06-25 14:59:20 -07001496 int total_phys_segments;
1497 int total_hw_segments;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001498
1499 /*
1500 * First check if the either of the requests are re-queued
1501 * requests. Can't merge them if they are.
1502 */
1503 if (req->special || next->special)
1504 return 0;
1505
1506 /*
Nikita Danilovdfa1a552005-06-25 14:59:20 -07001507 * Will it become too large?
Linus Torvalds1da177e2005-04-16 15:20:36 -07001508 */
1509 if ((req->nr_sectors + next->nr_sectors) > q->max_sectors)
1510 return 0;
1511
1512 total_phys_segments = req->nr_phys_segments + next->nr_phys_segments;
1513 if (blk_phys_contig_segment(q, req->biotail, next->bio))
1514 total_phys_segments--;
1515
1516 if (total_phys_segments > q->max_phys_segments)
1517 return 0;
1518
1519 total_hw_segments = req->nr_hw_segments + next->nr_hw_segments;
1520 if (blk_hw_contig_segment(q, req->biotail, next->bio)) {
1521 int len = req->biotail->bi_hw_back_size + next->bio->bi_hw_front_size;
1522 /*
1523 * propagate the combined length to the end of the requests
1524 */
1525 if (req->nr_hw_segments == 1)
1526 req->bio->bi_hw_front_size = len;
1527 if (next->nr_hw_segments == 1)
1528 next->biotail->bi_hw_back_size = len;
1529 total_hw_segments--;
1530 }
1531
1532 if (total_hw_segments > q->max_hw_segments)
1533 return 0;
1534
1535 /* Merge is OK... */
1536 req->nr_phys_segments = total_phys_segments;
1537 req->nr_hw_segments = total_hw_segments;
1538 return 1;
1539}
1540
1541/*
1542 * "plug" the device if there are no outstanding requests: this will
1543 * force the transfer to start only after we have put all the requests
1544 * on the list.
1545 *
1546 * This is called with interrupts off and no requests on the queue and
1547 * with the queue lock held.
1548 */
1549void blk_plug_device(request_queue_t *q)
1550{
1551 WARN_ON(!irqs_disabled());
1552
1553 /*
1554 * don't plug a stopped queue, it must be paired with blk_start_queue()
1555 * which will restart the queueing
1556 */
Coywolf Qi Hunt7daac492006-04-19 10:14:49 +02001557 if (blk_queue_stopped(q))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001558 return;
1559
Jens Axboe2056a782006-03-23 20:00:26 +01001560 if (!test_and_set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001561 mod_timer(&q->unplug_timer, jiffies + q->unplug_delay);
Jens Axboe2056a782006-03-23 20:00:26 +01001562 blk_add_trace_generic(q, NULL, 0, BLK_TA_PLUG);
1563 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001564}
1565
1566EXPORT_SYMBOL(blk_plug_device);
1567
1568/*
1569 * remove the queue from the plugged list, if present. called with
1570 * queue lock held and interrupts disabled.
1571 */
1572int blk_remove_plug(request_queue_t *q)
1573{
1574 WARN_ON(!irqs_disabled());
1575
1576 if (!test_and_clear_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags))
1577 return 0;
1578
1579 del_timer(&q->unplug_timer);
1580 return 1;
1581}
1582
1583EXPORT_SYMBOL(blk_remove_plug);
1584
1585/*
1586 * remove the plug and let it rip..
1587 */
1588void __generic_unplug_device(request_queue_t *q)
1589{
Coywolf Qi Hunt7daac492006-04-19 10:14:49 +02001590 if (unlikely(blk_queue_stopped(q)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001591 return;
1592
1593 if (!blk_remove_plug(q))
1594 return;
1595
Jens Axboe22e2c502005-06-27 10:55:12 +02001596 q->request_fn(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001597}
1598EXPORT_SYMBOL(__generic_unplug_device);
1599
1600/**
1601 * generic_unplug_device - fire a request queue
1602 * @q: The &request_queue_t in question
1603 *
1604 * Description:
1605 * Linux uses plugging to build bigger requests queues before letting
1606 * the device have at them. If a queue is plugged, the I/O scheduler
1607 * is still adding and merging requests on the queue. Once the queue
1608 * gets unplugged, the request_fn defined for the queue is invoked and
1609 * transfers started.
1610 **/
1611void generic_unplug_device(request_queue_t *q)
1612{
1613 spin_lock_irq(q->queue_lock);
1614 __generic_unplug_device(q);
1615 spin_unlock_irq(q->queue_lock);
1616}
1617EXPORT_SYMBOL(generic_unplug_device);
1618
1619static void blk_backing_dev_unplug(struct backing_dev_info *bdi,
1620 struct page *page)
1621{
1622 request_queue_t *q = bdi->unplug_io_data;
1623
1624 /*
1625 * devices don't necessarily have an ->unplug_fn defined
1626 */
Jens Axboe2056a782006-03-23 20:00:26 +01001627 if (q->unplug_fn) {
1628 blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL,
1629 q->rq.count[READ] + q->rq.count[WRITE]);
1630
Linus Torvalds1da177e2005-04-16 15:20:36 -07001631 q->unplug_fn(q);
Jens Axboe2056a782006-03-23 20:00:26 +01001632 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001633}
1634
1635static void blk_unplug_work(void *data)
1636{
1637 request_queue_t *q = data;
1638
Jens Axboe2056a782006-03-23 20:00:26 +01001639 blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL,
1640 q->rq.count[READ] + q->rq.count[WRITE]);
1641
Linus Torvalds1da177e2005-04-16 15:20:36 -07001642 q->unplug_fn(q);
1643}
1644
1645static void blk_unplug_timeout(unsigned long data)
1646{
1647 request_queue_t *q = (request_queue_t *)data;
1648
Jens Axboe2056a782006-03-23 20:00:26 +01001649 blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_TIMER, NULL,
1650 q->rq.count[READ] + q->rq.count[WRITE]);
1651
Linus Torvalds1da177e2005-04-16 15:20:36 -07001652 kblockd_schedule_work(&q->unplug_work);
1653}
1654
1655/**
1656 * blk_start_queue - restart a previously stopped queue
1657 * @q: The &request_queue_t in question
1658 *
1659 * Description:
1660 * blk_start_queue() will clear the stop flag on the queue, and call
1661 * the request_fn for the queue if it was in a stopped state when
1662 * entered. Also see blk_stop_queue(). Queue lock must be held.
1663 **/
1664void blk_start_queue(request_queue_t *q)
1665{
1666 clear_bit(QUEUE_FLAG_STOPPED, &q->queue_flags);
1667
1668 /*
1669 * one level of recursion is ok and is much faster than kicking
1670 * the unplug handling
1671 */
1672 if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) {
1673 q->request_fn(q);
1674 clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags);
1675 } else {
1676 blk_plug_device(q);
1677 kblockd_schedule_work(&q->unplug_work);
1678 }
1679}
1680
1681EXPORT_SYMBOL(blk_start_queue);
1682
1683/**
1684 * blk_stop_queue - stop a queue
1685 * @q: The &request_queue_t in question
1686 *
1687 * Description:
1688 * The Linux block layer assumes that a block driver will consume all
1689 * entries on the request queue when the request_fn strategy is called.
1690 * Often this will not happen, because of hardware limitations (queue
1691 * depth settings). If a device driver gets a 'queue full' response,
1692 * or if it simply chooses not to queue more I/O at one point, it can
1693 * call this function to prevent the request_fn from being called until
1694 * the driver has signalled it's ready to go again. This happens by calling
1695 * blk_start_queue() to restart queue operations. Queue lock must be held.
1696 **/
1697void blk_stop_queue(request_queue_t *q)
1698{
1699 blk_remove_plug(q);
1700 set_bit(QUEUE_FLAG_STOPPED, &q->queue_flags);
1701}
1702EXPORT_SYMBOL(blk_stop_queue);
1703
1704/**
1705 * blk_sync_queue - cancel any pending callbacks on a queue
1706 * @q: the queue
1707 *
1708 * Description:
1709 * The block layer may perform asynchronous callback activity
1710 * on a queue, such as calling the unplug function after a timeout.
1711 * A block device may call blk_sync_queue to ensure that any
1712 * such activity is cancelled, thus allowing it to release resources
1713 * the the callbacks might use. The caller must already have made sure
1714 * that its ->make_request_fn will not re-add plugging prior to calling
1715 * this function.
1716 *
1717 */
1718void blk_sync_queue(struct request_queue *q)
1719{
1720 del_timer_sync(&q->unplug_timer);
1721 kblockd_flush();
1722}
1723EXPORT_SYMBOL(blk_sync_queue);
1724
1725/**
1726 * blk_run_queue - run a single device queue
1727 * @q: The queue to run
1728 */
1729void blk_run_queue(struct request_queue *q)
1730{
1731 unsigned long flags;
1732
1733 spin_lock_irqsave(q->queue_lock, flags);
1734 blk_remove_plug(q);
Ken Chena2997382005-04-16 15:25:43 -07001735 if (!elv_queue_empty(q))
1736 q->request_fn(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001737 spin_unlock_irqrestore(q->queue_lock, flags);
1738}
1739EXPORT_SYMBOL(blk_run_queue);
1740
1741/**
1742 * blk_cleanup_queue: - release a &request_queue_t when it is no longer needed
Martin Waitza5802902006-04-02 13:59:55 +02001743 * @kobj: the kobj belonging of the request queue to be released
Linus Torvalds1da177e2005-04-16 15:20:36 -07001744 *
1745 * Description:
1746 * blk_cleanup_queue is the pair to blk_init_queue() or
1747 * blk_queue_make_request(). It should be called when a request queue is
1748 * being released; typically when a block device is being de-registered.
1749 * Currently, its primary task it to free all the &struct request
1750 * structures that were allocated to the queue and the queue itself.
1751 *
1752 * Caveat:
1753 * Hopefully the low level driver will have finished any
1754 * outstanding requests first...
1755 **/
Al Viro483f4af2006-03-18 18:34:37 -05001756static void blk_release_queue(struct kobject *kobj)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001757{
Al Viro483f4af2006-03-18 18:34:37 -05001758 request_queue_t *q = container_of(kobj, struct request_queue, kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001759 struct request_list *rl = &q->rq;
1760
Linus Torvalds1da177e2005-04-16 15:20:36 -07001761 blk_sync_queue(q);
1762
1763 if (rl->rq_pool)
1764 mempool_destroy(rl->rq_pool);
1765
1766 if (q->queue_tags)
1767 __blk_queue_free_tags(q);
1768
Jens Axboe2056a782006-03-23 20:00:26 +01001769 if (q->blk_trace)
1770 blk_trace_shutdown(q);
1771
Linus Torvalds1da177e2005-04-16 15:20:36 -07001772 kmem_cache_free(requestq_cachep, q);
1773}
1774
Al Viro483f4af2006-03-18 18:34:37 -05001775void blk_put_queue(request_queue_t *q)
1776{
1777 kobject_put(&q->kobj);
1778}
1779EXPORT_SYMBOL(blk_put_queue);
1780
1781void blk_cleanup_queue(request_queue_t * q)
1782{
1783 mutex_lock(&q->sysfs_lock);
1784 set_bit(QUEUE_FLAG_DEAD, &q->queue_flags);
1785 mutex_unlock(&q->sysfs_lock);
1786
1787 if (q->elevator)
1788 elevator_exit(q->elevator);
1789
1790 blk_put_queue(q);
1791}
1792
Linus Torvalds1da177e2005-04-16 15:20:36 -07001793EXPORT_SYMBOL(blk_cleanup_queue);
1794
1795static int blk_init_free_list(request_queue_t *q)
1796{
1797 struct request_list *rl = &q->rq;
1798
1799 rl->count[READ] = rl->count[WRITE] = 0;
1800 rl->starved[READ] = rl->starved[WRITE] = 0;
Tejun Heocb98fc82005-10-28 08:29:39 +02001801 rl->elvpriv = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001802 init_waitqueue_head(&rl->wait[READ]);
1803 init_waitqueue_head(&rl->wait[WRITE]);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001804
Christoph Lameter19460892005-06-23 00:08:19 -07001805 rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
1806 mempool_free_slab, request_cachep, q->node);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001807
1808 if (!rl->rq_pool)
1809 return -ENOMEM;
1810
1811 return 0;
1812}
1813
Al Viro8267e262005-10-21 03:20:53 -04001814request_queue_t *blk_alloc_queue(gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001815{
Christoph Lameter19460892005-06-23 00:08:19 -07001816 return blk_alloc_queue_node(gfp_mask, -1);
1817}
1818EXPORT_SYMBOL(blk_alloc_queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001819
Al Viro483f4af2006-03-18 18:34:37 -05001820static struct kobj_type queue_ktype;
1821
Al Viro8267e262005-10-21 03:20:53 -04001822request_queue_t *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
Christoph Lameter19460892005-06-23 00:08:19 -07001823{
1824 request_queue_t *q;
1825
1826 q = kmem_cache_alloc_node(requestq_cachep, gfp_mask, node_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001827 if (!q)
1828 return NULL;
1829
1830 memset(q, 0, sizeof(*q));
1831 init_timer(&q->unplug_timer);
Al Viro483f4af2006-03-18 18:34:37 -05001832
1833 snprintf(q->kobj.name, KOBJ_NAME_LEN, "%s", "queue");
1834 q->kobj.ktype = &queue_ktype;
1835 kobject_init(&q->kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001836
1837 q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug;
1838 q->backing_dev_info.unplug_io_data = q;
1839
Al Viro483f4af2006-03-18 18:34:37 -05001840 mutex_init(&q->sysfs_lock);
1841
Linus Torvalds1da177e2005-04-16 15:20:36 -07001842 return q;
1843}
Christoph Lameter19460892005-06-23 00:08:19 -07001844EXPORT_SYMBOL(blk_alloc_queue_node);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001845
1846/**
1847 * blk_init_queue - prepare a request queue for use with a block device
1848 * @rfn: The function to be called to process requests that have been
1849 * placed on the queue.
1850 * @lock: Request queue spin lock
1851 *
1852 * Description:
1853 * If a block device wishes to use the standard request handling procedures,
1854 * which sorts requests and coalesces adjacent requests, then it must
1855 * call blk_init_queue(). The function @rfn will be called when there
1856 * are requests on the queue that need to be processed. If the device
1857 * supports plugging, then @rfn may not be called immediately when requests
1858 * are available on the queue, but may be called at some time later instead.
1859 * Plugged queues are generally unplugged when a buffer belonging to one
1860 * of the requests on the queue is needed, or due to memory pressure.
1861 *
1862 * @rfn is not required, or even expected, to remove all requests off the
1863 * queue, but only as many as it can handle at a time. If it does leave
1864 * requests on the queue, it is responsible for arranging that the requests
1865 * get dealt with eventually.
1866 *
1867 * The queue spin lock must be held while manipulating the requests on the
1868 * request queue.
1869 *
1870 * Function returns a pointer to the initialized request queue, or NULL if
1871 * it didn't succeed.
1872 *
1873 * Note:
1874 * blk_init_queue() must be paired with a blk_cleanup_queue() call
1875 * when the block device is deactivated (such as at module unload).
1876 **/
Christoph Lameter19460892005-06-23 00:08:19 -07001877
Linus Torvalds1da177e2005-04-16 15:20:36 -07001878request_queue_t *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock)
1879{
Christoph Lameter19460892005-06-23 00:08:19 -07001880 return blk_init_queue_node(rfn, lock, -1);
1881}
1882EXPORT_SYMBOL(blk_init_queue);
1883
1884request_queue_t *
1885blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
1886{
1887 request_queue_t *q = blk_alloc_queue_node(GFP_KERNEL, node_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001888
1889 if (!q)
1890 return NULL;
1891
Christoph Lameter19460892005-06-23 00:08:19 -07001892 q->node = node_id;
Al Viro8669aaf2006-03-18 13:50:00 -05001893 if (blk_init_free_list(q)) {
1894 kmem_cache_free(requestq_cachep, q);
1895 return NULL;
1896 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001897
152587d2005-04-12 16:22:06 -05001898 /*
1899 * if caller didn't supply a lock, they get per-queue locking with
1900 * our embedded lock
1901 */
1902 if (!lock) {
1903 spin_lock_init(&q->__queue_lock);
1904 lock = &q->__queue_lock;
1905 }
1906
Linus Torvalds1da177e2005-04-16 15:20:36 -07001907 q->request_fn = rfn;
1908 q->back_merge_fn = ll_back_merge_fn;
1909 q->front_merge_fn = ll_front_merge_fn;
1910 q->merge_requests_fn = ll_merge_requests_fn;
1911 q->prep_rq_fn = NULL;
1912 q->unplug_fn = generic_unplug_device;
1913 q->queue_flags = (1 << QUEUE_FLAG_CLUSTER);
1914 q->queue_lock = lock;
1915
1916 blk_queue_segment_boundary(q, 0xffffffff);
1917
1918 blk_queue_make_request(q, __make_request);
1919 blk_queue_max_segment_size(q, MAX_SEGMENT_SIZE);
1920
1921 blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS);
1922 blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS);
1923
1924 /*
1925 * all done
1926 */
1927 if (!elevator_init(q, NULL)) {
1928 blk_queue_congestion_threshold(q);
1929 return q;
1930 }
1931
Al Viro8669aaf2006-03-18 13:50:00 -05001932 blk_put_queue(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001933 return NULL;
1934}
Christoph Lameter19460892005-06-23 00:08:19 -07001935EXPORT_SYMBOL(blk_init_queue_node);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001936
1937int blk_get_queue(request_queue_t *q)
1938{
Nick Pigginfde6ad22005-06-23 00:08:53 -07001939 if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) {
Al Viro483f4af2006-03-18 18:34:37 -05001940 kobject_get(&q->kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001941 return 0;
1942 }
1943
1944 return 1;
1945}
1946
1947EXPORT_SYMBOL(blk_get_queue);
1948
1949static inline void blk_free_request(request_queue_t *q, struct request *rq)
1950{
Tejun Heocb98fc82005-10-28 08:29:39 +02001951 if (rq->flags & REQ_ELVPRIV)
1952 elv_put_request(q, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001953 mempool_free(rq, q->rq.rq_pool);
1954}
1955
Jens Axboe22e2c502005-06-27 10:55:12 +02001956static inline struct request *
Tejun Heocb98fc82005-10-28 08:29:39 +02001957blk_alloc_request(request_queue_t *q, int rw, struct bio *bio,
Linus Torvalds5dd96242005-10-28 08:56:34 -07001958 int priv, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001959{
1960 struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask);
1961
1962 if (!rq)
1963 return NULL;
1964
1965 /*
1966 * first three bits are identical in rq->flags and bio->bi_rw,
1967 * see bio.h and blkdev.h
1968 */
1969 rq->flags = rw;
1970
Tejun Heocb98fc82005-10-28 08:29:39 +02001971 if (priv) {
1972 if (unlikely(elv_set_request(q, rq, bio, gfp_mask))) {
1973 mempool_free(rq, q->rq.rq_pool);
1974 return NULL;
1975 }
1976 rq->flags |= REQ_ELVPRIV;
1977 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001978
Tejun Heocb98fc82005-10-28 08:29:39 +02001979 return rq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001980}
1981
1982/*
1983 * ioc_batching returns true if the ioc is a valid batching request and
1984 * should be given priority access to a request.
1985 */
1986static inline int ioc_batching(request_queue_t *q, struct io_context *ioc)
1987{
1988 if (!ioc)
1989 return 0;
1990
1991 /*
1992 * Make sure the process is able to allocate at least 1 request
1993 * even if the batch times out, otherwise we could theoretically
1994 * lose wakeups.
1995 */
1996 return ioc->nr_batch_requests == q->nr_batching ||
1997 (ioc->nr_batch_requests > 0
1998 && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME));
1999}
2000
2001/*
2002 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
2003 * will cause the process to be a "batcher" on all queues in the system. This
2004 * is the behaviour we want though - once it gets a wakeup it should be given
2005 * a nice run.
2006 */
Adrian Bunk93d17d32005-06-25 14:59:10 -07002007static void ioc_set_batching(request_queue_t *q, struct io_context *ioc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002008{
2009 if (!ioc || ioc_batching(q, ioc))
2010 return;
2011
2012 ioc->nr_batch_requests = q->nr_batching;
2013 ioc->last_waited = jiffies;
2014}
2015
2016static void __freed_request(request_queue_t *q, int rw)
2017{
2018 struct request_list *rl = &q->rq;
2019
2020 if (rl->count[rw] < queue_congestion_off_threshold(q))
2021 clear_queue_congested(q, rw);
2022
2023 if (rl->count[rw] + 1 <= q->nr_requests) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002024 if (waitqueue_active(&rl->wait[rw]))
2025 wake_up(&rl->wait[rw]);
2026
2027 blk_clear_queue_full(q, rw);
2028 }
2029}
2030
2031/*
2032 * A request has just been released. Account for it, update the full and
2033 * congestion status, wake up any waiters. Called under q->queue_lock.
2034 */
Tejun Heocb98fc82005-10-28 08:29:39 +02002035static void freed_request(request_queue_t *q, int rw, int priv)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002036{
2037 struct request_list *rl = &q->rq;
2038
2039 rl->count[rw]--;
Tejun Heocb98fc82005-10-28 08:29:39 +02002040 if (priv)
2041 rl->elvpriv--;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002042
2043 __freed_request(q, rw);
2044
2045 if (unlikely(rl->starved[rw ^ 1]))
2046 __freed_request(q, rw ^ 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002047}
2048
2049#define blkdev_free_rq(list) list_entry((list)->next, struct request, queuelist)
2050/*
Nick Piggind6344532005-06-28 20:45:14 -07002051 * Get a free request, queue_lock must be held.
2052 * Returns NULL on failure, with queue_lock held.
2053 * Returns !NULL on success, with queue_lock *not held*.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002054 */
Jens Axboe22e2c502005-06-27 10:55:12 +02002055static struct request *get_request(request_queue_t *q, int rw, struct bio *bio,
Al Viro8267e262005-10-21 03:20:53 -04002056 gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002057{
2058 struct request *rq = NULL;
2059 struct request_list *rl = &q->rq;
Jens Axboe88ee5ef2005-11-12 11:09:12 +01002060 struct io_context *ioc = NULL;
2061 int may_queue, priv;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002062
Jens Axboe88ee5ef2005-11-12 11:09:12 +01002063 may_queue = elv_may_queue(q, rw, bio);
2064 if (may_queue == ELV_MQUEUE_NO)
2065 goto rq_starved;
2066
2067 if (rl->count[rw]+1 >= queue_congestion_on_threshold(q)) {
2068 if (rl->count[rw]+1 >= q->nr_requests) {
2069 ioc = current_io_context(GFP_ATOMIC);
2070 /*
2071 * The queue will fill after this allocation, so set
2072 * it as full, and mark this process as "batching".
2073 * This process will be allowed to complete a batch of
2074 * requests, others will be blocked.
2075 */
2076 if (!blk_queue_full(q, rw)) {
2077 ioc_set_batching(q, ioc);
2078 blk_set_queue_full(q, rw);
2079 } else {
2080 if (may_queue != ELV_MQUEUE_MUST
2081 && !ioc_batching(q, ioc)) {
2082 /*
2083 * The queue is full and the allocating
2084 * process is not a "batcher", and not
2085 * exempted by the IO scheduler
2086 */
2087 goto out;
2088 }
2089 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002090 }
Jens Axboe88ee5ef2005-11-12 11:09:12 +01002091 set_queue_congested(q, rw);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002092 }
2093
Jens Axboe082cf692005-06-28 16:35:11 +02002094 /*
2095 * Only allow batching queuers to allocate up to 50% over the defined
2096 * limit of requests, otherwise we could have thousands of requests
2097 * allocated with any setting of ->nr_requests
2098 */
Hugh Dickinsfd782a42005-06-29 15:15:40 +01002099 if (rl->count[rw] >= (3 * q->nr_requests / 2))
Jens Axboe082cf692005-06-28 16:35:11 +02002100 goto out;
Hugh Dickinsfd782a42005-06-29 15:15:40 +01002101
Linus Torvalds1da177e2005-04-16 15:20:36 -07002102 rl->count[rw]++;
2103 rl->starved[rw] = 0;
Tejun Heocb98fc82005-10-28 08:29:39 +02002104
Jens Axboe64521d12005-10-28 08:30:39 +02002105 priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
Tejun Heocb98fc82005-10-28 08:29:39 +02002106 if (priv)
2107 rl->elvpriv++;
2108
Linus Torvalds1da177e2005-04-16 15:20:36 -07002109 spin_unlock_irq(q->queue_lock);
2110
Tejun Heocb98fc82005-10-28 08:29:39 +02002111 rq = blk_alloc_request(q, rw, bio, priv, gfp_mask);
Jens Axboe88ee5ef2005-11-12 11:09:12 +01002112 if (unlikely(!rq)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002113 /*
2114 * Allocation failed presumably due to memory. Undo anything
2115 * we might have messed up.
2116 *
2117 * Allocating task should really be put onto the front of the
2118 * wait queue, but this is pretty rare.
2119 */
2120 spin_lock_irq(q->queue_lock);
Tejun Heocb98fc82005-10-28 08:29:39 +02002121 freed_request(q, rw, priv);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002122
2123 /*
2124 * in the very unlikely event that allocation failed and no
2125 * requests for this direction was pending, mark us starved
2126 * so that freeing of a request in the other direction will
2127 * notice us. another possible fix would be to split the
2128 * rq mempool into READ and WRITE
2129 */
2130rq_starved:
2131 if (unlikely(rl->count[rw] == 0))
2132 rl->starved[rw] = 1;
2133
Linus Torvalds1da177e2005-04-16 15:20:36 -07002134 goto out;
2135 }
2136
Jens Axboe88ee5ef2005-11-12 11:09:12 +01002137 /*
2138 * ioc may be NULL here, and ioc_batching will be false. That's
2139 * OK, if the queue is under the request limit then requests need
2140 * not count toward the nr_batch_requests limit. There will always
2141 * be some limit enforced by BLK_BATCH_TIME.
2142 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002143 if (ioc_batching(q, ioc))
2144 ioc->nr_batch_requests--;
2145
2146 rq_init(q, rq);
2147 rq->rl = rl;
Jens Axboe2056a782006-03-23 20:00:26 +01002148
2149 blk_add_trace_generic(q, bio, rw, BLK_TA_GETRQ);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002150out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002151 return rq;
2152}
2153
2154/*
2155 * No available requests for this queue, unplug the device and wait for some
2156 * requests to become available.
Nick Piggind6344532005-06-28 20:45:14 -07002157 *
2158 * Called with q->queue_lock held, and returns with it unlocked.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002159 */
Jens Axboe22e2c502005-06-27 10:55:12 +02002160static struct request *get_request_wait(request_queue_t *q, int rw,
2161 struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002162{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002163 struct request *rq;
2164
Nick Piggin450991b2005-06-28 20:45:13 -07002165 rq = get_request(q, rw, bio, GFP_NOIO);
2166 while (!rq) {
2167 DEFINE_WAIT(wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002168 struct request_list *rl = &q->rq;
2169
2170 prepare_to_wait_exclusive(&rl->wait[rw], &wait,
2171 TASK_UNINTERRUPTIBLE);
2172
Jens Axboe22e2c502005-06-27 10:55:12 +02002173 rq = get_request(q, rw, bio, GFP_NOIO);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002174
2175 if (!rq) {
2176 struct io_context *ioc;
2177
Jens Axboe2056a782006-03-23 20:00:26 +01002178 blk_add_trace_generic(q, bio, rw, BLK_TA_SLEEPRQ);
2179
Nick Piggind6344532005-06-28 20:45:14 -07002180 __generic_unplug_device(q);
2181 spin_unlock_irq(q->queue_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002182 io_schedule();
2183
2184 /*
2185 * After sleeping, we become a "batching" process and
2186 * will be able to allocate at least one request, and
2187 * up to a big batch of them for a small period time.
2188 * See ioc_batching, ioc_set_batching
2189 */
Nick Pigginfb3cc432005-06-28 20:45:15 -07002190 ioc = current_io_context(GFP_NOIO);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002191 ioc_set_batching(q, ioc);
Nick Piggind6344532005-06-28 20:45:14 -07002192
2193 spin_lock_irq(q->queue_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002194 }
2195 finish_wait(&rl->wait[rw], &wait);
Nick Piggin450991b2005-06-28 20:45:13 -07002196 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002197
2198 return rq;
2199}
2200
Al Viro8267e262005-10-21 03:20:53 -04002201struct request *blk_get_request(request_queue_t *q, int rw, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002202{
2203 struct request *rq;
2204
2205 BUG_ON(rw != READ && rw != WRITE);
2206
Nick Piggind6344532005-06-28 20:45:14 -07002207 spin_lock_irq(q->queue_lock);
2208 if (gfp_mask & __GFP_WAIT) {
Jens Axboe22e2c502005-06-27 10:55:12 +02002209 rq = get_request_wait(q, rw, NULL);
Nick Piggind6344532005-06-28 20:45:14 -07002210 } else {
Jens Axboe22e2c502005-06-27 10:55:12 +02002211 rq = get_request(q, rw, NULL, gfp_mask);
Nick Piggind6344532005-06-28 20:45:14 -07002212 if (!rq)
2213 spin_unlock_irq(q->queue_lock);
2214 }
2215 /* q->queue_lock is unlocked at this point */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002216
2217 return rq;
2218}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002219EXPORT_SYMBOL(blk_get_request);
2220
2221/**
2222 * blk_requeue_request - put a request back on queue
2223 * @q: request queue where request should be inserted
2224 * @rq: request to be inserted
2225 *
2226 * Description:
2227 * Drivers often keep queueing requests until the hardware cannot accept
2228 * more, when that condition happens we need to put the request back
2229 * on the queue. Must be called with queue lock held.
2230 */
2231void blk_requeue_request(request_queue_t *q, struct request *rq)
2232{
Jens Axboe2056a782006-03-23 20:00:26 +01002233 blk_add_trace_rq(q, rq, BLK_TA_REQUEUE);
2234
Linus Torvalds1da177e2005-04-16 15:20:36 -07002235 if (blk_rq_tagged(rq))
2236 blk_queue_end_tag(q, rq);
2237
2238 elv_requeue_request(q, rq);
2239}
2240
2241EXPORT_SYMBOL(blk_requeue_request);
2242
2243/**
2244 * blk_insert_request - insert a special request in to a request queue
2245 * @q: request queue where request should be inserted
2246 * @rq: request to be inserted
2247 * @at_head: insert request at head or tail of queue
2248 * @data: private data
Linus Torvalds1da177e2005-04-16 15:20:36 -07002249 *
2250 * Description:
2251 * Many block devices need to execute commands asynchronously, so they don't
2252 * block the whole kernel from preemption during request execution. This is
2253 * accomplished normally by inserting aritficial requests tagged as
2254 * REQ_SPECIAL in to the corresponding request queue, and letting them be
2255 * scheduled for actual execution by the request queue.
2256 *
2257 * We have the option of inserting the head or the tail of the queue.
2258 * Typically we use the tail for new ioctls and so forth. We use the head
2259 * of the queue for things like a QUEUE_FULL message from a device, or a
2260 * host that is unable to accept a particular command.
2261 */
2262void blk_insert_request(request_queue_t *q, struct request *rq,
Tejun Heo 867d1192005-04-24 02:06:05 -05002263 int at_head, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002264{
Tejun Heo 867d1192005-04-24 02:06:05 -05002265 int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002266 unsigned long flags;
2267
2268 /*
2269 * tell I/O scheduler that this isn't a regular read/write (ie it
2270 * must not attempt merges on this) and that it acts as a soft
2271 * barrier
2272 */
2273 rq->flags |= REQ_SPECIAL | REQ_SOFTBARRIER;
2274
2275 rq->special = data;
2276
2277 spin_lock_irqsave(q->queue_lock, flags);
2278
2279 /*
2280 * If command is tagged, release the tag
2281 */
Tejun Heo 867d1192005-04-24 02:06:05 -05002282 if (blk_rq_tagged(rq))
2283 blk_queue_end_tag(q, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002284
Tejun Heo 867d1192005-04-24 02:06:05 -05002285 drive_stat_acct(rq, rq->nr_sectors, 1);
2286 __elv_add_request(q, rq, where, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002287
Linus Torvalds1da177e2005-04-16 15:20:36 -07002288 if (blk_queue_plugged(q))
2289 __generic_unplug_device(q);
2290 else
2291 q->request_fn(q);
2292 spin_unlock_irqrestore(q->queue_lock, flags);
2293}
2294
2295EXPORT_SYMBOL(blk_insert_request);
2296
2297/**
2298 * blk_rq_map_user - map user data to a request, for REQ_BLOCK_PC usage
2299 * @q: request queue where request should be inserted
Christoph Hellwig 73747ae2005-06-20 14:21:01 +02002300 * @rq: request structure to fill
Linus Torvalds1da177e2005-04-16 15:20:36 -07002301 * @ubuf: the user buffer
2302 * @len: length of user data
2303 *
2304 * Description:
2305 * Data will be mapped directly for zero copy io, if possible. Otherwise
2306 * a kernel bounce buffer is used.
2307 *
2308 * A matching blk_rq_unmap_user() must be issued at the end of io, while
2309 * still in process context.
2310 *
2311 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
2312 * before being submitted to the device, as pages mapped may be out of
2313 * reach. It's the callers responsibility to make sure this happens. The
2314 * original bio must be passed back in to blk_rq_unmap_user() for proper
2315 * unmapping.
2316 */
Jens Axboedd1cab92005-06-20 14:06:01 +02002317int blk_rq_map_user(request_queue_t *q, struct request *rq, void __user *ubuf,
2318 unsigned int len)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002319{
2320 unsigned long uaddr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002321 struct bio *bio;
Jens Axboedd1cab92005-06-20 14:06:01 +02002322 int reading;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002323
Mike Christiedefd94b2005-12-05 02:37:06 -06002324 if (len > (q->max_hw_sectors << 9))
Jens Axboedd1cab92005-06-20 14:06:01 +02002325 return -EINVAL;
2326 if (!len || !ubuf)
2327 return -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002328
Jens Axboedd1cab92005-06-20 14:06:01 +02002329 reading = rq_data_dir(rq) == READ;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002330
2331 /*
2332 * if alignment requirement is satisfied, map in user pages for
2333 * direct dma. else, set up kernel bounce buffers
2334 */
2335 uaddr = (unsigned long) ubuf;
2336 if (!(uaddr & queue_dma_alignment(q)) && !(len & queue_dma_alignment(q)))
Jens Axboedd1cab92005-06-20 14:06:01 +02002337 bio = bio_map_user(q, NULL, uaddr, len, reading);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002338 else
Jens Axboedd1cab92005-06-20 14:06:01 +02002339 bio = bio_copy_user(q, uaddr, len, reading);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002340
2341 if (!IS_ERR(bio)) {
2342 rq->bio = rq->biotail = bio;
2343 blk_rq_bio_prep(q, rq, bio);
2344
2345 rq->buffer = rq->data = NULL;
2346 rq->data_len = len;
Jens Axboedd1cab92005-06-20 14:06:01 +02002347 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002348 }
2349
2350 /*
2351 * bio is the err-ptr
2352 */
Jens Axboedd1cab92005-06-20 14:06:01 +02002353 return PTR_ERR(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002354}
2355
2356EXPORT_SYMBOL(blk_rq_map_user);
2357
2358/**
James Bottomley f1970ba2005-06-20 14:06:52 +02002359 * blk_rq_map_user_iov - map user data to a request, for REQ_BLOCK_PC usage
2360 * @q: request queue where request should be inserted
2361 * @rq: request to map data to
2362 * @iov: pointer to the iovec
2363 * @iov_count: number of elements in the iovec
2364 *
2365 * Description:
2366 * Data will be mapped directly for zero copy io, if possible. Otherwise
2367 * a kernel bounce buffer is used.
2368 *
2369 * A matching blk_rq_unmap_user() must be issued at the end of io, while
2370 * still in process context.
2371 *
2372 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
2373 * before being submitted to the device, as pages mapped may be out of
2374 * reach. It's the callers responsibility to make sure this happens. The
2375 * original bio must be passed back in to blk_rq_unmap_user() for proper
2376 * unmapping.
2377 */
2378int blk_rq_map_user_iov(request_queue_t *q, struct request *rq,
2379 struct sg_iovec *iov, int iov_count)
2380{
2381 struct bio *bio;
2382
2383 if (!iov || iov_count <= 0)
2384 return -EINVAL;
2385
2386 /* we don't allow misaligned data like bio_map_user() does. If the
2387 * user is using sg, they're expected to know the alignment constraints
2388 * and respect them accordingly */
2389 bio = bio_map_user_iov(q, NULL, iov, iov_count, rq_data_dir(rq)== READ);
2390 if (IS_ERR(bio))
2391 return PTR_ERR(bio);
2392
2393 rq->bio = rq->biotail = bio;
2394 blk_rq_bio_prep(q, rq, bio);
2395 rq->buffer = rq->data = NULL;
2396 rq->data_len = bio->bi_size;
2397 return 0;
2398}
2399
2400EXPORT_SYMBOL(blk_rq_map_user_iov);
2401
2402/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07002403 * blk_rq_unmap_user - unmap a request with user data
Christoph Hellwig 73747ae2005-06-20 14:21:01 +02002404 * @bio: bio to be unmapped
Linus Torvalds1da177e2005-04-16 15:20:36 -07002405 * @ulen: length of user buffer
2406 *
2407 * Description:
Christoph Hellwig 73747ae2005-06-20 14:21:01 +02002408 * Unmap a bio previously mapped by blk_rq_map_user().
Linus Torvalds1da177e2005-04-16 15:20:36 -07002409 */
Jens Axboedd1cab92005-06-20 14:06:01 +02002410int blk_rq_unmap_user(struct bio *bio, unsigned int ulen)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002411{
2412 int ret = 0;
2413
2414 if (bio) {
2415 if (bio_flagged(bio, BIO_USER_MAPPED))
2416 bio_unmap_user(bio);
2417 else
2418 ret = bio_uncopy_user(bio);
2419 }
2420
Jens Axboedd1cab92005-06-20 14:06:01 +02002421 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002422}
2423
2424EXPORT_SYMBOL(blk_rq_unmap_user);
2425
2426/**
Mike Christie df46b9a2005-06-20 14:04:44 +02002427 * blk_rq_map_kern - map kernel data to a request, for REQ_BLOCK_PC usage
2428 * @q: request queue where request should be inserted
Christoph Hellwig 73747ae2005-06-20 14:21:01 +02002429 * @rq: request to fill
Mike Christie df46b9a2005-06-20 14:04:44 +02002430 * @kbuf: the kernel buffer
2431 * @len: length of user data
Christoph Hellwig 73747ae2005-06-20 14:21:01 +02002432 * @gfp_mask: memory allocation flags
Mike Christie df46b9a2005-06-20 14:04:44 +02002433 */
Jens Axboedd1cab92005-06-20 14:06:01 +02002434int blk_rq_map_kern(request_queue_t *q, struct request *rq, void *kbuf,
Al Viro8267e262005-10-21 03:20:53 -04002435 unsigned int len, gfp_t gfp_mask)
Mike Christie df46b9a2005-06-20 14:04:44 +02002436{
Mike Christie df46b9a2005-06-20 14:04:44 +02002437 struct bio *bio;
2438
Mike Christiedefd94b2005-12-05 02:37:06 -06002439 if (len > (q->max_hw_sectors << 9))
Jens Axboedd1cab92005-06-20 14:06:01 +02002440 return -EINVAL;
2441 if (!len || !kbuf)
2442 return -EINVAL;
Mike Christie df46b9a2005-06-20 14:04:44 +02002443
2444 bio = bio_map_kern(q, kbuf, len, gfp_mask);
Jens Axboedd1cab92005-06-20 14:06:01 +02002445 if (IS_ERR(bio))
2446 return PTR_ERR(bio);
Mike Christie df46b9a2005-06-20 14:04:44 +02002447
Jens Axboedd1cab92005-06-20 14:06:01 +02002448 if (rq_data_dir(rq) == WRITE)
2449 bio->bi_rw |= (1 << BIO_RW);
Mike Christie df46b9a2005-06-20 14:04:44 +02002450
Jens Axboedd1cab92005-06-20 14:06:01 +02002451 rq->bio = rq->biotail = bio;
2452 blk_rq_bio_prep(q, rq, bio);
Mike Christie df46b9a2005-06-20 14:04:44 +02002453
Jens Axboedd1cab92005-06-20 14:06:01 +02002454 rq->buffer = rq->data = NULL;
2455 rq->data_len = len;
2456 return 0;
Mike Christie df46b9a2005-06-20 14:04:44 +02002457}
2458
2459EXPORT_SYMBOL(blk_rq_map_kern);
2460
Christoph Hellwig 73747ae2005-06-20 14:21:01 +02002461/**
2462 * blk_execute_rq_nowait - insert a request into queue for execution
2463 * @q: queue to insert the request in
2464 * @bd_disk: matching gendisk
2465 * @rq: request to insert
2466 * @at_head: insert request at head or tail of queue
2467 * @done: I/O completion handler
2468 *
2469 * Description:
2470 * Insert a fully prepared request at the back of the io scheduler queue
2471 * for execution. Don't wait for completion.
2472 */
James Bottomley f1970ba2005-06-20 14:06:52 +02002473void blk_execute_rq_nowait(request_queue_t *q, struct gendisk *bd_disk,
2474 struct request *rq, int at_head,
Tejun Heo8ffdc652006-01-06 09:49:03 +01002475 rq_end_io_fn *done)
James Bottomley f1970ba2005-06-20 14:06:52 +02002476{
2477 int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
2478
2479 rq->rq_disk = bd_disk;
2480 rq->flags |= REQ_NOMERGE;
2481 rq->end_io = done;
Andrew Morton4c5d0bb2006-03-22 08:08:01 +01002482 WARN_ON(irqs_disabled());
2483 spin_lock_irq(q->queue_lock);
2484 __elv_add_request(q, rq, where, 1);
2485 __generic_unplug_device(q);
2486 spin_unlock_irq(q->queue_lock);
James Bottomley f1970ba2005-06-20 14:06:52 +02002487}
Mike Christie6e39b692005-11-11 05:30:24 -06002488EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
2489
Linus Torvalds1da177e2005-04-16 15:20:36 -07002490/**
2491 * blk_execute_rq - insert a request into queue for execution
2492 * @q: queue to insert the request in
2493 * @bd_disk: matching gendisk
2494 * @rq: request to insert
James Bottomley 994ca9a2005-06-20 14:11:09 +02002495 * @at_head: insert request at head or tail of queue
Linus Torvalds1da177e2005-04-16 15:20:36 -07002496 *
2497 * Description:
2498 * Insert a fully prepared request at the back of the io scheduler queue
Christoph Hellwig 73747ae2005-06-20 14:21:01 +02002499 * for execution and wait for completion.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002500 */
2501int blk_execute_rq(request_queue_t *q, struct gendisk *bd_disk,
James Bottomley 994ca9a2005-06-20 14:11:09 +02002502 struct request *rq, int at_head)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002503{
2504 DECLARE_COMPLETION(wait);
2505 char sense[SCSI_SENSE_BUFFERSIZE];
2506 int err = 0;
2507
Linus Torvalds1da177e2005-04-16 15:20:36 -07002508 /*
2509 * we need an extra reference to the request, so we can look at
2510 * it after io completion
2511 */
2512 rq->ref_count++;
2513
2514 if (!rq->sense) {
2515 memset(sense, 0, sizeof(sense));
2516 rq->sense = sense;
2517 rq->sense_len = 0;
2518 }
2519
Linus Torvalds1da177e2005-04-16 15:20:36 -07002520 rq->waiting = &wait;
James Bottomley 994ca9a2005-06-20 14:11:09 +02002521 blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002522 wait_for_completion(&wait);
2523 rq->waiting = NULL;
2524
2525 if (rq->errors)
2526 err = -EIO;
2527
2528 return err;
2529}
2530
2531EXPORT_SYMBOL(blk_execute_rq);
2532
2533/**
2534 * blkdev_issue_flush - queue a flush
2535 * @bdev: blockdev to issue flush for
2536 * @error_sector: error sector
2537 *
2538 * Description:
2539 * Issue a flush for the block device in question. Caller can supply
2540 * room for storing the error offset in case of a flush error, if they
2541 * wish to. Caller must run wait_for_completion() on its own.
2542 */
2543int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector)
2544{
2545 request_queue_t *q;
2546
2547 if (bdev->bd_disk == NULL)
2548 return -ENXIO;
2549
2550 q = bdev_get_queue(bdev);
2551 if (!q)
2552 return -ENXIO;
2553 if (!q->issue_flush_fn)
2554 return -EOPNOTSUPP;
2555
2556 return q->issue_flush_fn(q, bdev->bd_disk, error_sector);
2557}
2558
2559EXPORT_SYMBOL(blkdev_issue_flush);
2560
Adrian Bunk93d17d32005-06-25 14:59:10 -07002561static void drive_stat_acct(struct request *rq, int nr_sectors, int new_io)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002562{
2563 int rw = rq_data_dir(rq);
2564
2565 if (!blk_fs_request(rq) || !rq->rq_disk)
2566 return;
2567
Jens Axboed72d9042005-11-01 08:35:42 +01002568 if (!new_io) {
Jens Axboea3623572005-11-01 09:26:16 +01002569 __disk_stat_inc(rq->rq_disk, merges[rw]);
Jens Axboed72d9042005-11-01 08:35:42 +01002570 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002571 disk_round_stats(rq->rq_disk);
2572 rq->rq_disk->in_flight++;
2573 }
2574}
2575
2576/*
2577 * add-request adds a request to the linked list.
2578 * queue lock is held and interrupts disabled, as we muck with the
2579 * request queue list.
2580 */
2581static inline void add_request(request_queue_t * q, struct request * req)
2582{
2583 drive_stat_acct(req, req->nr_sectors, 1);
2584
2585 if (q->activity_fn)
2586 q->activity_fn(q->activity_data, rq_data_dir(req));
2587
2588 /*
2589 * elevator indicated where it wants this request to be
2590 * inserted at elevator_merge time
2591 */
2592 __elv_add_request(q, req, ELEVATOR_INSERT_SORT, 0);
2593}
2594
2595/*
2596 * disk_round_stats() - Round off the performance stats on a struct
2597 * disk_stats.
2598 *
2599 * The average IO queue length and utilisation statistics are maintained
2600 * by observing the current state of the queue length and the amount of
2601 * time it has been in this state for.
2602 *
2603 * Normally, that accounting is done on IO completion, but that can result
2604 * in more than a second's worth of IO being accounted for within any one
2605 * second, leading to >100% utilisation. To deal with that, we call this
2606 * function to do a round-off before returning the results when reading
2607 * /proc/diskstats. This accounts immediately for all queue usage up to
2608 * the current jiffies and restarts the counters again.
2609 */
2610void disk_round_stats(struct gendisk *disk)
2611{
2612 unsigned long now = jiffies;
2613
Chen, Kenneth Wb2982642005-10-13 21:49:29 +02002614 if (now == disk->stamp)
2615 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002616
Chen, Kenneth W20e5c812005-10-13 21:48:42 +02002617 if (disk->in_flight) {
2618 __disk_stat_add(disk, time_in_queue,
2619 disk->in_flight * (now - disk->stamp));
2620 __disk_stat_add(disk, io_ticks, (now - disk->stamp));
2621 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002622 disk->stamp = now;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002623}
2624
Jun'ichi "Nick" Nomura3eaf8402006-02-01 03:04:53 -08002625EXPORT_SYMBOL_GPL(disk_round_stats);
2626
Linus Torvalds1da177e2005-04-16 15:20:36 -07002627/*
2628 * queue lock must be held
2629 */
Mike Christie6e39b692005-11-11 05:30:24 -06002630void __blk_put_request(request_queue_t *q, struct request *req)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002631{
2632 struct request_list *rl = req->rl;
2633
2634 if (unlikely(!q))
2635 return;
2636 if (unlikely(--req->ref_count))
2637 return;
2638
Tejun Heo8922e162005-10-20 16:23:44 +02002639 elv_completed_request(q, req);
2640
Linus Torvalds1da177e2005-04-16 15:20:36 -07002641 req->rq_status = RQ_INACTIVE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002642 req->rl = NULL;
2643
2644 /*
2645 * Request may not have originated from ll_rw_blk. if not,
2646 * it didn't come out of our reserved rq pools
2647 */
2648 if (rl) {
2649 int rw = rq_data_dir(req);
Tejun Heocb98fc82005-10-28 08:29:39 +02002650 int priv = req->flags & REQ_ELVPRIV;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002651
Linus Torvalds1da177e2005-04-16 15:20:36 -07002652 BUG_ON(!list_empty(&req->queuelist));
2653
2654 blk_free_request(q, req);
Tejun Heocb98fc82005-10-28 08:29:39 +02002655 freed_request(q, rw, priv);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002656 }
2657}
2658
Mike Christie6e39b692005-11-11 05:30:24 -06002659EXPORT_SYMBOL_GPL(__blk_put_request);
2660
Linus Torvalds1da177e2005-04-16 15:20:36 -07002661void blk_put_request(struct request *req)
2662{
Tejun Heo8922e162005-10-20 16:23:44 +02002663 unsigned long flags;
2664 request_queue_t *q = req->q;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002665
Tejun Heo8922e162005-10-20 16:23:44 +02002666 /*
2667 * Gee, IDE calls in w/ NULL q. Fix IDE and remove the
2668 * following if (q) test.
2669 */
2670 if (q) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002671 spin_lock_irqsave(q->queue_lock, flags);
2672 __blk_put_request(q, req);
2673 spin_unlock_irqrestore(q->queue_lock, flags);
2674 }
2675}
2676
2677EXPORT_SYMBOL(blk_put_request);
2678
2679/**
2680 * blk_end_sync_rq - executes a completion event on a request
2681 * @rq: request to complete
Jens Axboefddfdea2006-01-31 15:24:34 +01002682 * @error: end io status of the request
Linus Torvalds1da177e2005-04-16 15:20:36 -07002683 */
Tejun Heo8ffdc652006-01-06 09:49:03 +01002684void blk_end_sync_rq(struct request *rq, int error)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002685{
2686 struct completion *waiting = rq->waiting;
2687
2688 rq->waiting = NULL;
2689 __blk_put_request(rq->q, rq);
2690
2691 /*
2692 * complete last, if this is a stack request the process (and thus
2693 * the rq pointer) could be invalid right after this complete()
2694 */
2695 complete(waiting);
2696}
2697EXPORT_SYMBOL(blk_end_sync_rq);
2698
2699/**
2700 * blk_congestion_wait - wait for a queue to become uncongested
2701 * @rw: READ or WRITE
2702 * @timeout: timeout in jiffies
2703 *
2704 * Waits for up to @timeout jiffies for a queue (any queue) to exit congestion.
2705 * If no queues are congested then just wait for the next request to be
2706 * returned.
2707 */
2708long blk_congestion_wait(int rw, long timeout)
2709{
2710 long ret;
2711 DEFINE_WAIT(wait);
2712 wait_queue_head_t *wqh = &congestion_wqh[rw];
2713
2714 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
2715 ret = io_schedule_timeout(timeout);
2716 finish_wait(wqh, &wait);
2717 return ret;
2718}
2719
2720EXPORT_SYMBOL(blk_congestion_wait);
2721
2722/*
2723 * Has to be called with the request spinlock acquired
2724 */
2725static int attempt_merge(request_queue_t *q, struct request *req,
2726 struct request *next)
2727{
2728 if (!rq_mergeable(req) || !rq_mergeable(next))
2729 return 0;
2730
2731 /*
2732 * not contigious
2733 */
2734 if (req->sector + req->nr_sectors != next->sector)
2735 return 0;
2736
2737 if (rq_data_dir(req) != rq_data_dir(next)
2738 || req->rq_disk != next->rq_disk
2739 || next->waiting || next->special)
2740 return 0;
2741
2742 /*
2743 * If we are allowed to merge, then append bio list
2744 * from next to rq and release next. merge_requests_fn
2745 * will have updated segment counts, update sector
2746 * counts here.
2747 */
2748 if (!q->merge_requests_fn(q, req, next))
2749 return 0;
2750
2751 /*
2752 * At this point we have either done a back merge
2753 * or front merge. We need the smaller start_time of
2754 * the merged requests to be the current request
2755 * for accounting purposes.
2756 */
2757 if (time_after(req->start_time, next->start_time))
2758 req->start_time = next->start_time;
2759
2760 req->biotail->bi_next = next->bio;
2761 req->biotail = next->biotail;
2762
2763 req->nr_sectors = req->hard_nr_sectors += next->hard_nr_sectors;
2764
2765 elv_merge_requests(q, req, next);
2766
2767 if (req->rq_disk) {
2768 disk_round_stats(req->rq_disk);
2769 req->rq_disk->in_flight--;
2770 }
2771
Jens Axboe22e2c502005-06-27 10:55:12 +02002772 req->ioprio = ioprio_best(req->ioprio, next->ioprio);
2773
Linus Torvalds1da177e2005-04-16 15:20:36 -07002774 __blk_put_request(q, next);
2775 return 1;
2776}
2777
2778static inline int attempt_back_merge(request_queue_t *q, struct request *rq)
2779{
2780 struct request *next = elv_latter_request(q, rq);
2781
2782 if (next)
2783 return attempt_merge(q, rq, next);
2784
2785 return 0;
2786}
2787
2788static inline int attempt_front_merge(request_queue_t *q, struct request *rq)
2789{
2790 struct request *prev = elv_former_request(q, rq);
2791
2792 if (prev)
2793 return attempt_merge(q, prev, rq);
2794
2795 return 0;
2796}
2797
Tejun Heo52d9e672006-01-06 09:49:58 +01002798static void init_request_from_bio(struct request *req, struct bio *bio)
2799{
2800 req->flags |= REQ_CMD;
2801
2802 /*
2803 * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST)
2804 */
2805 if (bio_rw_ahead(bio) || bio_failfast(bio))
2806 req->flags |= REQ_FAILFAST;
2807
2808 /*
2809 * REQ_BARRIER implies no merging, but lets make it explicit
2810 */
2811 if (unlikely(bio_barrier(bio)))
2812 req->flags |= (REQ_HARDBARRIER | REQ_NOMERGE);
2813
2814 req->errors = 0;
2815 req->hard_sector = req->sector = bio->bi_sector;
2816 req->hard_nr_sectors = req->nr_sectors = bio_sectors(bio);
2817 req->current_nr_sectors = req->hard_cur_sectors = bio_cur_sectors(bio);
2818 req->nr_phys_segments = bio_phys_segments(req->q, bio);
2819 req->nr_hw_segments = bio_hw_segments(req->q, bio);
2820 req->buffer = bio_data(bio); /* see ->buffer comment above */
2821 req->waiting = NULL;
2822 req->bio = req->biotail = bio;
2823 req->ioprio = bio_prio(bio);
2824 req->rq_disk = bio->bi_bdev->bd_disk;
2825 req->start_time = jiffies;
2826}
2827
Linus Torvalds1da177e2005-04-16 15:20:36 -07002828static int __make_request(request_queue_t *q, struct bio *bio)
2829{
Nick Piggin450991b2005-06-28 20:45:13 -07002830 struct request *req;
Jens Axboe4a534f92005-04-16 15:25:40 -07002831 int el_ret, rw, nr_sectors, cur_nr_sectors, barrier, err, sync;
Jens Axboe22e2c502005-06-27 10:55:12 +02002832 unsigned short prio;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002833 sector_t sector;
2834
2835 sector = bio->bi_sector;
2836 nr_sectors = bio_sectors(bio);
2837 cur_nr_sectors = bio_cur_sectors(bio);
Jens Axboe22e2c502005-06-27 10:55:12 +02002838 prio = bio_prio(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002839
2840 rw = bio_data_dir(bio);
Jens Axboe4a534f92005-04-16 15:25:40 -07002841 sync = bio_sync(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002842
2843 /*
2844 * low level driver can indicate that it wants pages above a
2845 * certain limit bounced to low memory (ie for highmem, or even
2846 * ISA dma in theory)
2847 */
2848 blk_queue_bounce(q, &bio);
2849
2850 spin_lock_prefetch(q->queue_lock);
2851
2852 barrier = bio_barrier(bio);
Tejun Heo797e7db2006-01-06 09:51:03 +01002853 if (unlikely(barrier) && (q->next_ordered == QUEUE_ORDERED_NONE)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002854 err = -EOPNOTSUPP;
2855 goto end_io;
2856 }
2857
Linus Torvalds1da177e2005-04-16 15:20:36 -07002858 spin_lock_irq(q->queue_lock);
2859
Nick Piggin450991b2005-06-28 20:45:13 -07002860 if (unlikely(barrier) || elv_queue_empty(q))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002861 goto get_rq;
2862
2863 el_ret = elv_merge(q, &req, bio);
2864 switch (el_ret) {
2865 case ELEVATOR_BACK_MERGE:
2866 BUG_ON(!rq_mergeable(req));
2867
2868 if (!q->back_merge_fn(q, req, bio))
2869 break;
2870
Jens Axboe2056a782006-03-23 20:00:26 +01002871 blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE);
2872
Linus Torvalds1da177e2005-04-16 15:20:36 -07002873 req->biotail->bi_next = bio;
2874 req->biotail = bio;
2875 req->nr_sectors = req->hard_nr_sectors += nr_sectors;
Jens Axboe22e2c502005-06-27 10:55:12 +02002876 req->ioprio = ioprio_best(req->ioprio, prio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002877 drive_stat_acct(req, nr_sectors, 0);
2878 if (!attempt_back_merge(q, req))
2879 elv_merged_request(q, req);
2880 goto out;
2881
2882 case ELEVATOR_FRONT_MERGE:
2883 BUG_ON(!rq_mergeable(req));
2884
2885 if (!q->front_merge_fn(q, req, bio))
2886 break;
2887
Jens Axboe2056a782006-03-23 20:00:26 +01002888 blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE);
2889
Linus Torvalds1da177e2005-04-16 15:20:36 -07002890 bio->bi_next = req->bio;
2891 req->bio = bio;
2892
2893 /*
2894 * may not be valid. if the low level driver said
2895 * it didn't need a bounce buffer then it better
2896 * not touch req->buffer either...
2897 */
2898 req->buffer = bio_data(bio);
2899 req->current_nr_sectors = cur_nr_sectors;
2900 req->hard_cur_sectors = cur_nr_sectors;
2901 req->sector = req->hard_sector = sector;
2902 req->nr_sectors = req->hard_nr_sectors += nr_sectors;
Jens Axboe22e2c502005-06-27 10:55:12 +02002903 req->ioprio = ioprio_best(req->ioprio, prio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002904 drive_stat_acct(req, nr_sectors, 0);
2905 if (!attempt_front_merge(q, req))
2906 elv_merged_request(q, req);
2907 goto out;
2908
Nick Piggin450991b2005-06-28 20:45:13 -07002909 /* ELV_NO_MERGE: elevator says don't/can't merge. */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002910 default:
Nick Piggin450991b2005-06-28 20:45:13 -07002911 ;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002912 }
2913
Linus Torvalds1da177e2005-04-16 15:20:36 -07002914get_rq:
Nick Piggin450991b2005-06-28 20:45:13 -07002915 /*
2916 * Grab a free request. This is might sleep but can not fail.
Nick Piggind6344532005-06-28 20:45:14 -07002917 * Returns with the queue unlocked.
Nick Piggin450991b2005-06-28 20:45:13 -07002918 */
Nick Piggin450991b2005-06-28 20:45:13 -07002919 req = get_request_wait(q, rw, bio);
Nick Piggind6344532005-06-28 20:45:14 -07002920
Nick Piggin450991b2005-06-28 20:45:13 -07002921 /*
2922 * After dropping the lock and possibly sleeping here, our request
2923 * may now be mergeable after it had proven unmergeable (above).
2924 * We don't worry about that case for efficiency. It won't happen
2925 * often, and the elevators are able to handle it.
2926 */
Tejun Heo52d9e672006-01-06 09:49:58 +01002927 init_request_from_bio(req, bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002928
Nick Piggin450991b2005-06-28 20:45:13 -07002929 spin_lock_irq(q->queue_lock);
2930 if (elv_queue_empty(q))
2931 blk_plug_device(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002932 add_request(q, req);
2933out:
Jens Axboe4a534f92005-04-16 15:25:40 -07002934 if (sync)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002935 __generic_unplug_device(q);
2936
2937 spin_unlock_irq(q->queue_lock);
2938 return 0;
2939
2940end_io:
2941 bio_endio(bio, nr_sectors << 9, err);
2942 return 0;
2943}
2944
2945/*
2946 * If bio->bi_dev is a partition, remap the location
2947 */
2948static inline void blk_partition_remap(struct bio *bio)
2949{
2950 struct block_device *bdev = bio->bi_bdev;
2951
2952 if (bdev != bdev->bd_contains) {
2953 struct hd_struct *p = bdev->bd_part;
Jens Axboea3623572005-11-01 09:26:16 +01002954 const int rw = bio_data_dir(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002955
Jens Axboea3623572005-11-01 09:26:16 +01002956 p->sectors[rw] += bio_sectors(bio);
2957 p->ios[rw]++;
2958
Linus Torvalds1da177e2005-04-16 15:20:36 -07002959 bio->bi_sector += p->start_sect;
2960 bio->bi_bdev = bdev->bd_contains;
2961 }
2962}
2963
Linus Torvalds1da177e2005-04-16 15:20:36 -07002964static void handle_bad_sector(struct bio *bio)
2965{
2966 char b[BDEVNAME_SIZE];
2967
2968 printk(KERN_INFO "attempt to access beyond end of device\n");
2969 printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n",
2970 bdevname(bio->bi_bdev, b),
2971 bio->bi_rw,
2972 (unsigned long long)bio->bi_sector + bio_sectors(bio),
2973 (long long)(bio->bi_bdev->bd_inode->i_size >> 9));
2974
2975 set_bit(BIO_EOF, &bio->bi_flags);
2976}
2977
2978/**
2979 * generic_make_request: hand a buffer to its device driver for I/O
2980 * @bio: The bio describing the location in memory and on the device.
2981 *
2982 * generic_make_request() is used to make I/O requests of block
2983 * devices. It is passed a &struct bio, which describes the I/O that needs
2984 * to be done.
2985 *
2986 * generic_make_request() does not return any status. The
2987 * success/failure status of the request, along with notification of
2988 * completion, is delivered asynchronously through the bio->bi_end_io
2989 * function described (one day) else where.
2990 *
2991 * The caller of generic_make_request must make sure that bi_io_vec
2992 * are set to describe the memory buffer, and that bi_dev and bi_sector are
2993 * set to describe the device address, and the
2994 * bi_end_io and optionally bi_private are set to describe how
2995 * completion notification should be signaled.
2996 *
2997 * generic_make_request and the drivers it calls may use bi_next if this
2998 * bio happens to be merged with someone else, and may change bi_dev and
2999 * bi_sector for remaps as it sees fit. So the values of these fields
3000 * should NOT be depended on after the call to generic_make_request.
3001 */
3002void generic_make_request(struct bio *bio)
3003{
3004 request_queue_t *q;
3005 sector_t maxsector;
3006 int ret, nr_sectors = bio_sectors(bio);
Jens Axboe2056a782006-03-23 20:00:26 +01003007 dev_t old_dev;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003008
3009 might_sleep();
3010 /* Test device or partition size, when known. */
3011 maxsector = bio->bi_bdev->bd_inode->i_size >> 9;
3012 if (maxsector) {
3013 sector_t sector = bio->bi_sector;
3014
3015 if (maxsector < nr_sectors || maxsector - nr_sectors < sector) {
3016 /*
3017 * This may well happen - the kernel calls bread()
3018 * without checking the size of the device, e.g., when
3019 * mounting a device.
3020 */
3021 handle_bad_sector(bio);
3022 goto end_io;
3023 }
3024 }
3025
3026 /*
3027 * Resolve the mapping until finished. (drivers are
3028 * still free to implement/resolve their own stacking
3029 * by explicitly returning 0)
3030 *
3031 * NOTE: we don't repeat the blk_size check for each new device.
3032 * Stacking drivers are expected to know what they are doing.
3033 */
Jens Axboe2056a782006-03-23 20:00:26 +01003034 maxsector = -1;
3035 old_dev = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003036 do {
3037 char b[BDEVNAME_SIZE];
3038
3039 q = bdev_get_queue(bio->bi_bdev);
3040 if (!q) {
3041 printk(KERN_ERR
3042 "generic_make_request: Trying to access "
3043 "nonexistent block-device %s (%Lu)\n",
3044 bdevname(bio->bi_bdev, b),
3045 (long long) bio->bi_sector);
3046end_io:
3047 bio_endio(bio, bio->bi_size, -EIO);
3048 break;
3049 }
3050
3051 if (unlikely(bio_sectors(bio) > q->max_hw_sectors)) {
3052 printk("bio too big device %s (%u > %u)\n",
3053 bdevname(bio->bi_bdev, b),
3054 bio_sectors(bio),
3055 q->max_hw_sectors);
3056 goto end_io;
3057 }
3058
Nick Pigginfde6ad22005-06-23 00:08:53 -07003059 if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003060 goto end_io;
3061
Linus Torvalds1da177e2005-04-16 15:20:36 -07003062 /*
3063 * If this device has partitions, remap block n
3064 * of partition p to block n+start(p) of the disk.
3065 */
3066 blk_partition_remap(bio);
3067
Jens Axboe2056a782006-03-23 20:00:26 +01003068 if (maxsector != -1)
3069 blk_add_trace_remap(q, bio, old_dev, bio->bi_sector,
3070 maxsector);
3071
3072 blk_add_trace_bio(q, bio, BLK_TA_QUEUE);
3073
3074 maxsector = bio->bi_sector;
3075 old_dev = bio->bi_bdev->bd_dev;
3076
Linus Torvalds1da177e2005-04-16 15:20:36 -07003077 ret = q->make_request_fn(q, bio);
3078 } while (ret);
3079}
3080
3081EXPORT_SYMBOL(generic_make_request);
3082
3083/**
3084 * submit_bio: submit a bio to the block device layer for I/O
3085 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
3086 * @bio: The &struct bio which describes the I/O
3087 *
3088 * submit_bio() is very similar in purpose to generic_make_request(), and
3089 * uses that function to do most of the work. Both are fairly rough
3090 * interfaces, @bio must be presetup and ready for I/O.
3091 *
3092 */
3093void submit_bio(int rw, struct bio *bio)
3094{
3095 int count = bio_sectors(bio);
3096
3097 BIO_BUG_ON(!bio->bi_size);
3098 BIO_BUG_ON(!bio->bi_io_vec);
Jens Axboe22e2c502005-06-27 10:55:12 +02003099 bio->bi_rw |= rw;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003100 if (rw & WRITE)
3101 mod_page_state(pgpgout, count);
3102 else
3103 mod_page_state(pgpgin, count);
3104
3105 if (unlikely(block_dump)) {
3106 char b[BDEVNAME_SIZE];
3107 printk(KERN_DEBUG "%s(%d): %s block %Lu on %s\n",
3108 current->comm, current->pid,
3109 (rw & WRITE) ? "WRITE" : "READ",
3110 (unsigned long long)bio->bi_sector,
3111 bdevname(bio->bi_bdev,b));
3112 }
3113
3114 generic_make_request(bio);
3115}
3116
3117EXPORT_SYMBOL(submit_bio);
3118
Adrian Bunk93d17d32005-06-25 14:59:10 -07003119static void blk_recalc_rq_segments(struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003120{
3121 struct bio *bio, *prevbio = NULL;
3122 int nr_phys_segs, nr_hw_segs;
3123 unsigned int phys_size, hw_size;
3124 request_queue_t *q = rq->q;
3125
3126 if (!rq->bio)
3127 return;
3128
3129 phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0;
3130 rq_for_each_bio(bio, rq) {
3131 /* Force bio hw/phys segs to be recalculated. */
3132 bio->bi_flags &= ~(1 << BIO_SEG_VALID);
3133
3134 nr_phys_segs += bio_phys_segments(q, bio);
3135 nr_hw_segs += bio_hw_segments(q, bio);
3136 if (prevbio) {
3137 int pseg = phys_size + prevbio->bi_size + bio->bi_size;
3138 int hseg = hw_size + prevbio->bi_size + bio->bi_size;
3139
3140 if (blk_phys_contig_segment(q, prevbio, bio) &&
3141 pseg <= q->max_segment_size) {
3142 nr_phys_segs--;
3143 phys_size += prevbio->bi_size + bio->bi_size;
3144 } else
3145 phys_size = 0;
3146
3147 if (blk_hw_contig_segment(q, prevbio, bio) &&
3148 hseg <= q->max_segment_size) {
3149 nr_hw_segs--;
3150 hw_size += prevbio->bi_size + bio->bi_size;
3151 } else
3152 hw_size = 0;
3153 }
3154 prevbio = bio;
3155 }
3156
3157 rq->nr_phys_segments = nr_phys_segs;
3158 rq->nr_hw_segments = nr_hw_segs;
3159}
3160
Adrian Bunk93d17d32005-06-25 14:59:10 -07003161static void blk_recalc_rq_sectors(struct request *rq, int nsect)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003162{
3163 if (blk_fs_request(rq)) {
3164 rq->hard_sector += nsect;
3165 rq->hard_nr_sectors -= nsect;
3166
3167 /*
3168 * Move the I/O submission pointers ahead if required.
3169 */
3170 if ((rq->nr_sectors >= rq->hard_nr_sectors) &&
3171 (rq->sector <= rq->hard_sector)) {
3172 rq->sector = rq->hard_sector;
3173 rq->nr_sectors = rq->hard_nr_sectors;
3174 rq->hard_cur_sectors = bio_cur_sectors(rq->bio);
3175 rq->current_nr_sectors = rq->hard_cur_sectors;
3176 rq->buffer = bio_data(rq->bio);
3177 }
3178
3179 /*
3180 * if total number of sectors is less than the first segment
3181 * size, something has gone terribly wrong
3182 */
3183 if (rq->nr_sectors < rq->current_nr_sectors) {
3184 printk("blk: request botched\n");
3185 rq->nr_sectors = rq->current_nr_sectors;
3186 }
3187 }
3188}
3189
3190static int __end_that_request_first(struct request *req, int uptodate,
3191 int nr_bytes)
3192{
3193 int total_bytes, bio_nbytes, error, next_idx = 0;
3194 struct bio *bio;
3195
Jens Axboe2056a782006-03-23 20:00:26 +01003196 blk_add_trace_rq(req->q, req, BLK_TA_COMPLETE);
3197
Linus Torvalds1da177e2005-04-16 15:20:36 -07003198 /*
3199 * extend uptodate bool to allow < 0 value to be direct io error
3200 */
3201 error = 0;
3202 if (end_io_error(uptodate))
3203 error = !uptodate ? -EIO : uptodate;
3204
3205 /*
3206 * for a REQ_BLOCK_PC request, we want to carry any eventual
3207 * sense key with us all the way through
3208 */
3209 if (!blk_pc_request(req))
3210 req->errors = 0;
3211
3212 if (!uptodate) {
3213 if (blk_fs_request(req) && !(req->flags & REQ_QUIET))
3214 printk("end_request: I/O error, dev %s, sector %llu\n",
3215 req->rq_disk ? req->rq_disk->disk_name : "?",
3216 (unsigned long long)req->sector);
3217 }
3218
Jens Axboed72d9042005-11-01 08:35:42 +01003219 if (blk_fs_request(req) && req->rq_disk) {
Jens Axboea3623572005-11-01 09:26:16 +01003220 const int rw = rq_data_dir(req);
3221
Jens Axboe53e86062006-01-17 11:09:27 +01003222 disk_stat_add(req->rq_disk, sectors[rw], nr_bytes >> 9);
Jens Axboed72d9042005-11-01 08:35:42 +01003223 }
3224
Linus Torvalds1da177e2005-04-16 15:20:36 -07003225 total_bytes = bio_nbytes = 0;
3226 while ((bio = req->bio) != NULL) {
3227 int nbytes;
3228
3229 if (nr_bytes >= bio->bi_size) {
3230 req->bio = bio->bi_next;
3231 nbytes = bio->bi_size;
Tejun Heo797e7db2006-01-06 09:51:03 +01003232 if (!ordered_bio_endio(req, bio, nbytes, error))
3233 bio_endio(bio, nbytes, error);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003234 next_idx = 0;
3235 bio_nbytes = 0;
3236 } else {
3237 int idx = bio->bi_idx + next_idx;
3238
3239 if (unlikely(bio->bi_idx >= bio->bi_vcnt)) {
3240 blk_dump_rq_flags(req, "__end_that");
3241 printk("%s: bio idx %d >= vcnt %d\n",
3242 __FUNCTION__,
3243 bio->bi_idx, bio->bi_vcnt);
3244 break;
3245 }
3246
3247 nbytes = bio_iovec_idx(bio, idx)->bv_len;
3248 BIO_BUG_ON(nbytes > bio->bi_size);
3249
3250 /*
3251 * not a complete bvec done
3252 */
3253 if (unlikely(nbytes > nr_bytes)) {
3254 bio_nbytes += nr_bytes;
3255 total_bytes += nr_bytes;
3256 break;
3257 }
3258
3259 /*
3260 * advance to the next vector
3261 */
3262 next_idx++;
3263 bio_nbytes += nbytes;
3264 }
3265
3266 total_bytes += nbytes;
3267 nr_bytes -= nbytes;
3268
3269 if ((bio = req->bio)) {
3270 /*
3271 * end more in this run, or just return 'not-done'
3272 */
3273 if (unlikely(nr_bytes <= 0))
3274 break;
3275 }
3276 }
3277
3278 /*
3279 * completely done
3280 */
3281 if (!req->bio)
3282 return 0;
3283
3284 /*
3285 * if the request wasn't completed, update state
3286 */
3287 if (bio_nbytes) {
Tejun Heo797e7db2006-01-06 09:51:03 +01003288 if (!ordered_bio_endio(req, bio, bio_nbytes, error))
3289 bio_endio(bio, bio_nbytes, error);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003290 bio->bi_idx += next_idx;
3291 bio_iovec(bio)->bv_offset += nr_bytes;
3292 bio_iovec(bio)->bv_len -= nr_bytes;
3293 }
3294
3295 blk_recalc_rq_sectors(req, total_bytes >> 9);
3296 blk_recalc_rq_segments(req);
3297 return 1;
3298}
3299
3300/**
3301 * end_that_request_first - end I/O on a request
3302 * @req: the request being processed
3303 * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error
3304 * @nr_sectors: number of sectors to end I/O on
3305 *
3306 * Description:
3307 * Ends I/O on a number of sectors attached to @req, and sets it up
3308 * for the next range of segments (if any) in the cluster.
3309 *
3310 * Return:
3311 * 0 - we are done with this request, call end_that_request_last()
3312 * 1 - still buffers pending for this request
3313 **/
3314int end_that_request_first(struct request *req, int uptodate, int nr_sectors)
3315{
3316 return __end_that_request_first(req, uptodate, nr_sectors << 9);
3317}
3318
3319EXPORT_SYMBOL(end_that_request_first);
3320
3321/**
3322 * end_that_request_chunk - end I/O on a request
3323 * @req: the request being processed
3324 * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error
3325 * @nr_bytes: number of bytes to complete
3326 *
3327 * Description:
3328 * Ends I/O on a number of bytes attached to @req, and sets it up
3329 * for the next range of segments (if any). Like end_that_request_first(),
3330 * but deals with bytes instead of sectors.
3331 *
3332 * Return:
3333 * 0 - we are done with this request, call end_that_request_last()
3334 * 1 - still buffers pending for this request
3335 **/
3336int end_that_request_chunk(struct request *req, int uptodate, int nr_bytes)
3337{
3338 return __end_that_request_first(req, uptodate, nr_bytes);
3339}
3340
3341EXPORT_SYMBOL(end_that_request_chunk);
3342
3343/*
Jens Axboeff856ba2006-01-09 16:02:34 +01003344 * splice the completion data to a local structure and hand off to
3345 * process_completion_queue() to complete the requests
3346 */
3347static void blk_done_softirq(struct softirq_action *h)
3348{
3349 struct list_head *cpu_list;
3350 LIST_HEAD(local_list);
3351
3352 local_irq_disable();
3353 cpu_list = &__get_cpu_var(blk_cpu_done);
3354 list_splice_init(cpu_list, &local_list);
3355 local_irq_enable();
3356
3357 while (!list_empty(&local_list)) {
3358 struct request *rq = list_entry(local_list.next, struct request, donelist);
3359
3360 list_del_init(&rq->donelist);
3361 rq->q->softirq_done_fn(rq);
3362 }
3363}
3364
3365#ifdef CONFIG_HOTPLUG_CPU
3366
3367static int blk_cpu_notify(struct notifier_block *self, unsigned long action,
3368 void *hcpu)
3369{
3370 /*
3371 * If a CPU goes away, splice its entries to the current CPU
3372 * and trigger a run of the softirq
3373 */
3374 if (action == CPU_DEAD) {
3375 int cpu = (unsigned long) hcpu;
3376
3377 local_irq_disable();
3378 list_splice_init(&per_cpu(blk_cpu_done, cpu),
3379 &__get_cpu_var(blk_cpu_done));
3380 raise_softirq_irqoff(BLOCK_SOFTIRQ);
3381 local_irq_enable();
3382 }
3383
3384 return NOTIFY_OK;
3385}
3386
3387
Chandra Seetharaman649bbaa2006-04-24 19:35:15 -07003388static struct notifier_block blk_cpu_notifier = {
Jens Axboeff856ba2006-01-09 16:02:34 +01003389 .notifier_call = blk_cpu_notify,
3390};
3391
3392#endif /* CONFIG_HOTPLUG_CPU */
3393
3394/**
3395 * blk_complete_request - end I/O on a request
3396 * @req: the request being processed
3397 *
3398 * Description:
3399 * Ends all I/O on a request. It does not handle partial completions,
3400 * unless the driver actually implements this in its completionc callback
3401 * through requeueing. Theh actual completion happens out-of-order,
3402 * through a softirq handler. The user must have registered a completion
3403 * callback through blk_queue_softirq_done().
3404 **/
3405
3406void blk_complete_request(struct request *req)
3407{
3408 struct list_head *cpu_list;
3409 unsigned long flags;
3410
3411 BUG_ON(!req->q->softirq_done_fn);
3412
3413 local_irq_save(flags);
3414
3415 cpu_list = &__get_cpu_var(blk_cpu_done);
3416 list_add_tail(&req->donelist, cpu_list);
3417 raise_softirq_irqoff(BLOCK_SOFTIRQ);
3418
3419 local_irq_restore(flags);
3420}
3421
3422EXPORT_SYMBOL(blk_complete_request);
3423
3424/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07003425 * queue lock must be held
3426 */
Tejun Heo8ffdc652006-01-06 09:49:03 +01003427void end_that_request_last(struct request *req, int uptodate)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003428{
3429 struct gendisk *disk = req->rq_disk;
Tejun Heo8ffdc652006-01-06 09:49:03 +01003430 int error;
3431
3432 /*
3433 * extend uptodate bool to allow < 0 value to be direct io error
3434 */
3435 error = 0;
3436 if (end_io_error(uptodate))
3437 error = !uptodate ? -EIO : uptodate;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003438
3439 if (unlikely(laptop_mode) && blk_fs_request(req))
3440 laptop_io_completion();
3441
3442 if (disk && blk_fs_request(req)) {
3443 unsigned long duration = jiffies - req->start_time;
Jens Axboea3623572005-11-01 09:26:16 +01003444 const int rw = rq_data_dir(req);
3445
3446 __disk_stat_inc(disk, ios[rw]);
3447 __disk_stat_add(disk, ticks[rw], duration);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003448 disk_round_stats(disk);
3449 disk->in_flight--;
3450 }
3451 if (req->end_io)
Tejun Heo8ffdc652006-01-06 09:49:03 +01003452 req->end_io(req, error);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003453 else
3454 __blk_put_request(req->q, req);
3455}
3456
3457EXPORT_SYMBOL(end_that_request_last);
3458
3459void end_request(struct request *req, int uptodate)
3460{
3461 if (!end_that_request_first(req, uptodate, req->hard_cur_sectors)) {
3462 add_disk_randomness(req->rq_disk);
3463 blkdev_dequeue_request(req);
Tejun Heo8ffdc652006-01-06 09:49:03 +01003464 end_that_request_last(req, uptodate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003465 }
3466}
3467
3468EXPORT_SYMBOL(end_request);
3469
3470void blk_rq_bio_prep(request_queue_t *q, struct request *rq, struct bio *bio)
3471{
3472 /* first three bits are identical in rq->flags and bio->bi_rw */
3473 rq->flags |= (bio->bi_rw & 7);
3474
3475 rq->nr_phys_segments = bio_phys_segments(q, bio);
3476 rq->nr_hw_segments = bio_hw_segments(q, bio);
3477 rq->current_nr_sectors = bio_cur_sectors(bio);
3478 rq->hard_cur_sectors = rq->current_nr_sectors;
3479 rq->hard_nr_sectors = rq->nr_sectors = bio_sectors(bio);
3480 rq->buffer = bio_data(bio);
3481
3482 rq->bio = rq->biotail = bio;
3483}
3484
3485EXPORT_SYMBOL(blk_rq_bio_prep);
3486
3487int kblockd_schedule_work(struct work_struct *work)
3488{
3489 return queue_work(kblockd_workqueue, work);
3490}
3491
3492EXPORT_SYMBOL(kblockd_schedule_work);
3493
3494void kblockd_flush(void)
3495{
3496 flush_workqueue(kblockd_workqueue);
3497}
3498EXPORT_SYMBOL(kblockd_flush);
3499
3500int __init blk_dev_init(void)
3501{
Jens Axboeff856ba2006-01-09 16:02:34 +01003502 int i;
3503
Linus Torvalds1da177e2005-04-16 15:20:36 -07003504 kblockd_workqueue = create_workqueue("kblockd");
3505 if (!kblockd_workqueue)
3506 panic("Failed to create kblockd\n");
3507
3508 request_cachep = kmem_cache_create("blkdev_requests",
3509 sizeof(struct request), 0, SLAB_PANIC, NULL, NULL);
3510
3511 requestq_cachep = kmem_cache_create("blkdev_queue",
3512 sizeof(request_queue_t), 0, SLAB_PANIC, NULL, NULL);
3513
3514 iocontext_cachep = kmem_cache_create("blkdev_ioc",
3515 sizeof(struct io_context), 0, SLAB_PANIC, NULL, NULL);
3516
KAMEZAWA Hiroyuki0a945022006-03-28 01:56:37 -08003517 for_each_possible_cpu(i)
Jens Axboeff856ba2006-01-09 16:02:34 +01003518 INIT_LIST_HEAD(&per_cpu(blk_cpu_done, i));
3519
3520 open_softirq(BLOCK_SOFTIRQ, blk_done_softirq, NULL);
3521#ifdef CONFIG_HOTPLUG_CPU
3522 register_cpu_notifier(&blk_cpu_notifier);
3523#endif
3524
Linus Torvalds1da177e2005-04-16 15:20:36 -07003525 blk_max_low_pfn = max_low_pfn;
3526 blk_max_pfn = max_pfn;
3527
3528 return 0;
3529}
3530
3531/*
3532 * IO Context helper functions
3533 */
3534void put_io_context(struct io_context *ioc)
3535{
3536 if (ioc == NULL)
3537 return;
3538
3539 BUG_ON(atomic_read(&ioc->refcount) == 0);
3540
3541 if (atomic_dec_and_test(&ioc->refcount)) {
Jens Axboee2d74ac2006-03-28 08:59:01 +02003542 struct cfq_io_context *cic;
3543
Al Viro334e94d2006-03-18 15:05:53 -05003544 rcu_read_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003545 if (ioc->aic && ioc->aic->dtor)
3546 ioc->aic->dtor(ioc->aic);
Jens Axboee2d74ac2006-03-28 08:59:01 +02003547 if (ioc->cic_root.rb_node != NULL) {
Jens Axboe7143dd42006-03-28 09:00:28 +02003548 struct rb_node *n = rb_first(&ioc->cic_root);
3549
3550 cic = rb_entry(n, struct cfq_io_context, rb_node);
Jens Axboee2d74ac2006-03-28 08:59:01 +02003551 cic->dtor(ioc);
3552 }
Al Viro334e94d2006-03-18 15:05:53 -05003553 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003554
3555 kmem_cache_free(iocontext_cachep, ioc);
3556 }
3557}
3558EXPORT_SYMBOL(put_io_context);
3559
3560/* Called by the exitting task */
3561void exit_io_context(void)
3562{
3563 unsigned long flags;
3564 struct io_context *ioc;
Jens Axboee2d74ac2006-03-28 08:59:01 +02003565 struct cfq_io_context *cic;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003566
3567 local_irq_save(flags);
Jens Axboe22e2c502005-06-27 10:55:12 +02003568 task_lock(current);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003569 ioc = current->io_context;
3570 current->io_context = NULL;
Jens Axboe22e2c502005-06-27 10:55:12 +02003571 ioc->task = NULL;
3572 task_unlock(current);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003573 local_irq_restore(flags);
3574
3575 if (ioc->aic && ioc->aic->exit)
3576 ioc->aic->exit(ioc->aic);
Jens Axboee2d74ac2006-03-28 08:59:01 +02003577 if (ioc->cic_root.rb_node != NULL) {
3578 cic = rb_entry(rb_first(&ioc->cic_root), struct cfq_io_context, rb_node);
3579 cic->exit(ioc);
3580 }
3581
Linus Torvalds1da177e2005-04-16 15:20:36 -07003582 put_io_context(ioc);
3583}
3584
3585/*
3586 * If the current task has no IO context then create one and initialise it.
Nick Pigginfb3cc432005-06-28 20:45:15 -07003587 * Otherwise, return its existing IO context.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003588 *
Nick Pigginfb3cc432005-06-28 20:45:15 -07003589 * This returned IO context doesn't have a specifically elevated refcount,
3590 * but since the current task itself holds a reference, the context can be
3591 * used in general code, so long as it stays within `current` context.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003592 */
Al Viro8267e262005-10-21 03:20:53 -04003593struct io_context *current_io_context(gfp_t gfp_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003594{
3595 struct task_struct *tsk = current;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003596 struct io_context *ret;
3597
Linus Torvalds1da177e2005-04-16 15:20:36 -07003598 ret = tsk->io_context;
Nick Pigginfb3cc432005-06-28 20:45:15 -07003599 if (likely(ret))
3600 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003601
3602 ret = kmem_cache_alloc(iocontext_cachep, gfp_flags);
3603 if (ret) {
3604 atomic_set(&ret->refcount, 1);
Jens Axboe22e2c502005-06-27 10:55:12 +02003605 ret->task = current;
3606 ret->set_ioprio = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003607 ret->last_waited = jiffies; /* doesn't matter... */
3608 ret->nr_batch_requests = 0; /* because this is 0 */
3609 ret->aic = NULL;
Jens Axboee2d74ac2006-03-28 08:59:01 +02003610 ret->cic_root.rb_node = NULL;
Nick Pigginfb3cc432005-06-28 20:45:15 -07003611 tsk->io_context = ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003612 }
3613
3614 return ret;
3615}
Nick Pigginfb3cc432005-06-28 20:45:15 -07003616EXPORT_SYMBOL(current_io_context);
3617
3618/*
3619 * If the current task has no IO context then create one and initialise it.
3620 * If it does have a context, take a ref on it.
3621 *
3622 * This is always called in the context of the task which submitted the I/O.
3623 */
Al Viro8267e262005-10-21 03:20:53 -04003624struct io_context *get_io_context(gfp_t gfp_flags)
Nick Pigginfb3cc432005-06-28 20:45:15 -07003625{
3626 struct io_context *ret;
3627 ret = current_io_context(gfp_flags);
3628 if (likely(ret))
3629 atomic_inc(&ret->refcount);
3630 return ret;
3631}
Linus Torvalds1da177e2005-04-16 15:20:36 -07003632EXPORT_SYMBOL(get_io_context);
3633
3634void copy_io_context(struct io_context **pdst, struct io_context **psrc)
3635{
3636 struct io_context *src = *psrc;
3637 struct io_context *dst = *pdst;
3638
3639 if (src) {
3640 BUG_ON(atomic_read(&src->refcount) == 0);
3641 atomic_inc(&src->refcount);
3642 put_io_context(dst);
3643 *pdst = src;
3644 }
3645}
3646EXPORT_SYMBOL(copy_io_context);
3647
3648void swap_io_context(struct io_context **ioc1, struct io_context **ioc2)
3649{
3650 struct io_context *temp;
3651 temp = *ioc1;
3652 *ioc1 = *ioc2;
3653 *ioc2 = temp;
3654}
3655EXPORT_SYMBOL(swap_io_context);
3656
3657/*
3658 * sysfs parts below
3659 */
3660struct queue_sysfs_entry {
3661 struct attribute attr;
3662 ssize_t (*show)(struct request_queue *, char *);
3663 ssize_t (*store)(struct request_queue *, const char *, size_t);
3664};
3665
3666static ssize_t
3667queue_var_show(unsigned int var, char *page)
3668{
3669 return sprintf(page, "%d\n", var);
3670}
3671
3672static ssize_t
3673queue_var_store(unsigned long *var, const char *page, size_t count)
3674{
3675 char *p = (char *) page;
3676
3677 *var = simple_strtoul(p, &p, 10);
3678 return count;
3679}
3680
3681static ssize_t queue_requests_show(struct request_queue *q, char *page)
3682{
3683 return queue_var_show(q->nr_requests, (page));
3684}
3685
3686static ssize_t
3687queue_requests_store(struct request_queue *q, const char *page, size_t count)
3688{
3689 struct request_list *rl = &q->rq;
Al Viroc981ff92006-03-18 13:51:29 -05003690 unsigned long nr;
3691 int ret = queue_var_store(&nr, page, count);
3692 if (nr < BLKDEV_MIN_RQ)
3693 nr = BLKDEV_MIN_RQ;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003694
Al Viroc981ff92006-03-18 13:51:29 -05003695 spin_lock_irq(q->queue_lock);
3696 q->nr_requests = nr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003697 blk_queue_congestion_threshold(q);
3698
3699 if (rl->count[READ] >= queue_congestion_on_threshold(q))
3700 set_queue_congested(q, READ);
3701 else if (rl->count[READ] < queue_congestion_off_threshold(q))
3702 clear_queue_congested(q, READ);
3703
3704 if (rl->count[WRITE] >= queue_congestion_on_threshold(q))
3705 set_queue_congested(q, WRITE);
3706 else if (rl->count[WRITE] < queue_congestion_off_threshold(q))
3707 clear_queue_congested(q, WRITE);
3708
3709 if (rl->count[READ] >= q->nr_requests) {
3710 blk_set_queue_full(q, READ);
3711 } else if (rl->count[READ]+1 <= q->nr_requests) {
3712 blk_clear_queue_full(q, READ);
3713 wake_up(&rl->wait[READ]);
3714 }
3715
3716 if (rl->count[WRITE] >= q->nr_requests) {
3717 blk_set_queue_full(q, WRITE);
3718 } else if (rl->count[WRITE]+1 <= q->nr_requests) {
3719 blk_clear_queue_full(q, WRITE);
3720 wake_up(&rl->wait[WRITE]);
3721 }
Al Viroc981ff92006-03-18 13:51:29 -05003722 spin_unlock_irq(q->queue_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003723 return ret;
3724}
3725
3726static ssize_t queue_ra_show(struct request_queue *q, char *page)
3727{
3728 int ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10);
3729
3730 return queue_var_show(ra_kb, (page));
3731}
3732
3733static ssize_t
3734queue_ra_store(struct request_queue *q, const char *page, size_t count)
3735{
3736 unsigned long ra_kb;
3737 ssize_t ret = queue_var_store(&ra_kb, page, count);
3738
3739 spin_lock_irq(q->queue_lock);
3740 if (ra_kb > (q->max_sectors >> 1))
3741 ra_kb = (q->max_sectors >> 1);
3742
3743 q->backing_dev_info.ra_pages = ra_kb >> (PAGE_CACHE_SHIFT - 10);
3744 spin_unlock_irq(q->queue_lock);
3745
3746 return ret;
3747}
3748
3749static ssize_t queue_max_sectors_show(struct request_queue *q, char *page)
3750{
3751 int max_sectors_kb = q->max_sectors >> 1;
3752
3753 return queue_var_show(max_sectors_kb, (page));
3754}
3755
3756static ssize_t
3757queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
3758{
3759 unsigned long max_sectors_kb,
3760 max_hw_sectors_kb = q->max_hw_sectors >> 1,
3761 page_kb = 1 << (PAGE_CACHE_SHIFT - 10);
3762 ssize_t ret = queue_var_store(&max_sectors_kb, page, count);
3763 int ra_kb;
3764
3765 if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
3766 return -EINVAL;
3767 /*
3768 * Take the queue lock to update the readahead and max_sectors
3769 * values synchronously:
3770 */
3771 spin_lock_irq(q->queue_lock);
3772 /*
3773 * Trim readahead window as well, if necessary:
3774 */
3775 ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10);
3776 if (ra_kb > max_sectors_kb)
3777 q->backing_dev_info.ra_pages =
3778 max_sectors_kb >> (PAGE_CACHE_SHIFT - 10);
3779
3780 q->max_sectors = max_sectors_kb << 1;
3781 spin_unlock_irq(q->queue_lock);
3782
3783 return ret;
3784}
3785
3786static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page)
3787{
3788 int max_hw_sectors_kb = q->max_hw_sectors >> 1;
3789
3790 return queue_var_show(max_hw_sectors_kb, (page));
3791}
3792
3793
3794static struct queue_sysfs_entry queue_requests_entry = {
3795 .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
3796 .show = queue_requests_show,
3797 .store = queue_requests_store,
3798};
3799
3800static struct queue_sysfs_entry queue_ra_entry = {
3801 .attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR },
3802 .show = queue_ra_show,
3803 .store = queue_ra_store,
3804};
3805
3806static struct queue_sysfs_entry queue_max_sectors_entry = {
3807 .attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR },
3808 .show = queue_max_sectors_show,
3809 .store = queue_max_sectors_store,
3810};
3811
3812static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
3813 .attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO },
3814 .show = queue_max_hw_sectors_show,
3815};
3816
3817static struct queue_sysfs_entry queue_iosched_entry = {
3818 .attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR },
3819 .show = elv_iosched_show,
3820 .store = elv_iosched_store,
3821};
3822
3823static struct attribute *default_attrs[] = {
3824 &queue_requests_entry.attr,
3825 &queue_ra_entry.attr,
3826 &queue_max_hw_sectors_entry.attr,
3827 &queue_max_sectors_entry.attr,
3828 &queue_iosched_entry.attr,
3829 NULL,
3830};
3831
3832#define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
3833
3834static ssize_t
3835queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
3836{
3837 struct queue_sysfs_entry *entry = to_queue(attr);
Al Viro483f4af2006-03-18 18:34:37 -05003838 request_queue_t *q = container_of(kobj, struct request_queue, kobj);
3839 ssize_t res;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003840
Linus Torvalds1da177e2005-04-16 15:20:36 -07003841 if (!entry->show)
Dmitry Torokhov6c1852a2005-04-29 01:26:06 -05003842 return -EIO;
Al Viro483f4af2006-03-18 18:34:37 -05003843 mutex_lock(&q->sysfs_lock);
3844 if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
3845 mutex_unlock(&q->sysfs_lock);
3846 return -ENOENT;
3847 }
3848 res = entry->show(q, page);
3849 mutex_unlock(&q->sysfs_lock);
3850 return res;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003851}
3852
3853static ssize_t
3854queue_attr_store(struct kobject *kobj, struct attribute *attr,
3855 const char *page, size_t length)
3856{
3857 struct queue_sysfs_entry *entry = to_queue(attr);
Al Viro483f4af2006-03-18 18:34:37 -05003858 request_queue_t *q = container_of(kobj, struct request_queue, kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003859
Al Viro483f4af2006-03-18 18:34:37 -05003860 ssize_t res;
3861
Linus Torvalds1da177e2005-04-16 15:20:36 -07003862 if (!entry->store)
Dmitry Torokhov6c1852a2005-04-29 01:26:06 -05003863 return -EIO;
Al Viro483f4af2006-03-18 18:34:37 -05003864 mutex_lock(&q->sysfs_lock);
3865 if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
3866 mutex_unlock(&q->sysfs_lock);
3867 return -ENOENT;
3868 }
3869 res = entry->store(q, page, length);
3870 mutex_unlock(&q->sysfs_lock);
3871 return res;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003872}
3873
3874static struct sysfs_ops queue_sysfs_ops = {
3875 .show = queue_attr_show,
3876 .store = queue_attr_store,
3877};
3878
Adrian Bunk93d17d32005-06-25 14:59:10 -07003879static struct kobj_type queue_ktype = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003880 .sysfs_ops = &queue_sysfs_ops,
3881 .default_attrs = default_attrs,
Al Viro483f4af2006-03-18 18:34:37 -05003882 .release = blk_release_queue,
Linus Torvalds1da177e2005-04-16 15:20:36 -07003883};
3884
3885int blk_register_queue(struct gendisk *disk)
3886{
3887 int ret;
3888
3889 request_queue_t *q = disk->queue;
3890
3891 if (!q || !q->request_fn)
3892 return -ENXIO;
3893
3894 q->kobj.parent = kobject_get(&disk->kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003895
Al Viro483f4af2006-03-18 18:34:37 -05003896 ret = kobject_add(&q->kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003897 if (ret < 0)
3898 return ret;
3899
Al Viro483f4af2006-03-18 18:34:37 -05003900 kobject_uevent(&q->kobj, KOBJ_ADD);
3901
Linus Torvalds1da177e2005-04-16 15:20:36 -07003902 ret = elv_register_queue(q);
3903 if (ret) {
Al Viro483f4af2006-03-18 18:34:37 -05003904 kobject_uevent(&q->kobj, KOBJ_REMOVE);
3905 kobject_del(&q->kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003906 return ret;
3907 }
3908
3909 return 0;
3910}
3911
3912void blk_unregister_queue(struct gendisk *disk)
3913{
3914 request_queue_t *q = disk->queue;
3915
3916 if (q && q->request_fn) {
3917 elv_unregister_queue(q);
3918
Al Viro483f4af2006-03-18 18:34:37 -05003919 kobject_uevent(&q->kobj, KOBJ_REMOVE);
3920 kobject_del(&q->kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003921 kobject_put(&disk->kobj);
3922 }
3923}