blob: 61d6b3c65b6697105a432378ba452a86ebc346bf [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 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070013#include <linux/kernel.h>
14#include <linux/module.h>
15#include <linux/backing-dev.h>
16#include <linux/bio.h>
17#include <linux/blkdev.h>
18#include <linux/highmem.h>
19#include <linux/mm.h>
20#include <linux/kernel_stat.h>
21#include <linux/string.h>
22#include <linux/init.h>
23#include <linux/bootmem.h> /* for max_pfn/max_low_pfn */
24#include <linux/completion.h>
25#include <linux/slab.h>
26#include <linux/swap.h>
27#include <linux/writeback.h>
Jens Axboeff856ba2006-01-09 16:02:34 +010028#include <linux/interrupt.h>
29#include <linux/cpu.h>
Jens Axboe2056a782006-03-23 20:00:26 +010030#include <linux/blktrace_api.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070031
32/*
33 * for max sense size
34 */
35#include <scsi/scsi_cmnd.h>
36
37static void blk_unplug_work(void *data);
38static void blk_unplug_timeout(unsigned long data);
Adrian Bunk93d17d32005-06-25 14:59:10 -070039static void drive_stat_acct(struct request *rq, int nr_sectors, int new_io);
Tejun Heo52d9e672006-01-06 09:49:58 +010040static void init_request_from_bio(struct request *req, struct bio *bio);
41static int __make_request(request_queue_t *q, struct bio *bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -070042
43/*
44 * For the allocated request tables
45 */
46static kmem_cache_t *request_cachep;
47
48/*
49 * For queue allocation
50 */
51static kmem_cache_t *requestq_cachep;
52
53/*
54 * For io context allocations
55 */
56static kmem_cache_t *iocontext_cachep;
57
58static wait_queue_head_t congestion_wqh[2] = {
59 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
60 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
61 };
62
63/*
64 * Controlling structure to kblockd
65 */
Jens Axboeff856ba2006-01-09 16:02:34 +010066static struct workqueue_struct *kblockd_workqueue;
Linus Torvalds1da177e2005-04-16 15:20:36 -070067
68unsigned long blk_max_low_pfn, blk_max_pfn;
69
70EXPORT_SYMBOL(blk_max_low_pfn);
71EXPORT_SYMBOL(blk_max_pfn);
72
Jens Axboeff856ba2006-01-09 16:02:34 +010073static DEFINE_PER_CPU(struct list_head, blk_cpu_done);
74
Linus Torvalds1da177e2005-04-16 15:20:36 -070075/* Amount of time in which a process may batch requests */
76#define BLK_BATCH_TIME (HZ/50UL)
77
78/* Number of requests a "batching" process may submit */
79#define BLK_BATCH_REQ 32
80
81/*
82 * Return the threshold (number of used requests) at which the queue is
83 * considered to be congested. It include a little hysteresis to keep the
84 * context switch rate down.
85 */
86static inline int queue_congestion_on_threshold(struct request_queue *q)
87{
88 return q->nr_congestion_on;
89}
90
91/*
92 * The threshold at which a queue is considered to be uncongested
93 */
94static inline int queue_congestion_off_threshold(struct request_queue *q)
95{
96 return q->nr_congestion_off;
97}
98
99static void blk_queue_congestion_threshold(struct request_queue *q)
100{
101 int nr;
102
103 nr = q->nr_requests - (q->nr_requests / 8) + 1;
104 if (nr > q->nr_requests)
105 nr = q->nr_requests;
106 q->nr_congestion_on = nr;
107
108 nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1;
109 if (nr < 1)
110 nr = 1;
111 q->nr_congestion_off = nr;
112}
113
114/*
115 * A queue has just exitted congestion. Note this in the global counter of
116 * congested queues, and wake up anyone who was waiting for requests to be
117 * put back.
118 */
119static void clear_queue_congested(request_queue_t *q, int rw)
120{
121 enum bdi_state bit;
122 wait_queue_head_t *wqh = &congestion_wqh[rw];
123
124 bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
125 clear_bit(bit, &q->backing_dev_info.state);
126 smp_mb__after_clear_bit();
127 if (waitqueue_active(wqh))
128 wake_up(wqh);
129}
130
131/*
132 * A queue has just entered congestion. Flag that in the queue's VM-visible
133 * state flags and increment the global gounter of congested queues.
134 */
135static void set_queue_congested(request_queue_t *q, int rw)
136{
137 enum bdi_state bit;
138
139 bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
140 set_bit(bit, &q->backing_dev_info.state);
141}
142
143/**
144 * blk_get_backing_dev_info - get the address of a queue's backing_dev_info
145 * @bdev: device
146 *
147 * Locates the passed device's request queue and returns the address of its
148 * backing_dev_info
149 *
150 * Will return NULL if the request queue cannot be located.
151 */
152struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev)
153{
154 struct backing_dev_info *ret = NULL;
155 request_queue_t *q = bdev_get_queue(bdev);
156
157 if (q)
158 ret = &q->backing_dev_info;
159 return ret;
160}
161
162EXPORT_SYMBOL(blk_get_backing_dev_info);
163
164void blk_queue_activity_fn(request_queue_t *q, activity_fn *fn, void *data)
165{
166 q->activity_fn = fn;
167 q->activity_data = data;
168}
169
170EXPORT_SYMBOL(blk_queue_activity_fn);
171
172/**
173 * blk_queue_prep_rq - set a prepare_request function for queue
174 * @q: queue
175 * @pfn: prepare_request function
176 *
177 * It's possible for a queue to register a prepare_request callback which
178 * is invoked before the request is handed to the request_fn. The goal of
179 * the function is to prepare a request for I/O, it can be used to build a
180 * cdb from the request data for instance.
181 *
182 */
183void blk_queue_prep_rq(request_queue_t *q, prep_rq_fn *pfn)
184{
185 q->prep_rq_fn = pfn;
186}
187
188EXPORT_SYMBOL(blk_queue_prep_rq);
189
190/**
191 * blk_queue_merge_bvec - set a merge_bvec function for queue
192 * @q: queue
193 * @mbfn: merge_bvec_fn
194 *
195 * Usually queues have static limitations on the max sectors or segments that
196 * we can put in a request. Stacking drivers may have some settings that
197 * are dynamic, and thus we have to query the queue whether it is ok to
198 * add a new bio_vec to a bio at a given offset or not. If the block device
199 * has such limitations, it needs to register a merge_bvec_fn to control
200 * the size of bio's sent to it. Note that a block device *must* allow a
201 * single page to be added to an empty bio. The block device driver may want
202 * to use the bio_split() function to deal with these bio's. By default
203 * no merge_bvec_fn is defined for a queue, and only the fixed limits are
204 * honored.
205 */
206void blk_queue_merge_bvec(request_queue_t *q, merge_bvec_fn *mbfn)
207{
208 q->merge_bvec_fn = mbfn;
209}
210
211EXPORT_SYMBOL(blk_queue_merge_bvec);
212
Jens Axboeff856ba2006-01-09 16:02:34 +0100213void blk_queue_softirq_done(request_queue_t *q, softirq_done_fn *fn)
214{
215 q->softirq_done_fn = fn;
216}
217
218EXPORT_SYMBOL(blk_queue_softirq_done);
219
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220/**
221 * blk_queue_make_request - define an alternate make_request function for a device
222 * @q: the request queue for the device to be affected
223 * @mfn: the alternate make_request function
224 *
225 * Description:
226 * The normal way for &struct bios to be passed to a device
227 * driver is for them to be collected into requests on a request
228 * queue, and then to allow the device driver to select requests
229 * off that queue when it is ready. This works well for many block
230 * devices. However some block devices (typically virtual devices
231 * such as md or lvm) do not benefit from the processing on the
232 * request queue, and are served best by having the requests passed
233 * directly to them. This can be achieved by providing a function
234 * to blk_queue_make_request().
235 *
236 * Caveat:
237 * The driver that does this *must* be able to deal appropriately
238 * with buffers in "highmemory". This can be accomplished by either calling
239 * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling
240 * blk_queue_bounce() to create a buffer in normal memory.
241 **/
242void blk_queue_make_request(request_queue_t * q, make_request_fn * mfn)
243{
244 /*
245 * set defaults
246 */
247 q->nr_requests = BLKDEV_MAX_RQ;
Stuart McLaren309c0a12005-09-06 15:17:47 -0700248 blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS);
249 blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250 q->make_request_fn = mfn;
251 q->backing_dev_info.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
252 q->backing_dev_info.state = 0;
253 q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY;
Mike Christiedefd94b2005-12-05 02:37:06 -0600254 blk_queue_max_sectors(q, SAFE_MAX_SECTORS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255 blk_queue_hardsect_size(q, 512);
256 blk_queue_dma_alignment(q, 511);
257 blk_queue_congestion_threshold(q);
258 q->nr_batching = BLK_BATCH_REQ;
259
260 q->unplug_thresh = 4; /* hmm */
261 q->unplug_delay = (3 * HZ) / 1000; /* 3 milliseconds */
262 if (q->unplug_delay == 0)
263 q->unplug_delay = 1;
264
265 INIT_WORK(&q->unplug_work, blk_unplug_work, q);
266
267 q->unplug_timer.function = blk_unplug_timeout;
268 q->unplug_timer.data = (unsigned long)q;
269
270 /*
271 * by default assume old behaviour and bounce for any highmem page
272 */
273 blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH);
274
275 blk_queue_activity_fn(q, NULL, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276}
277
278EXPORT_SYMBOL(blk_queue_make_request);
279
280static inline void rq_init(request_queue_t *q, struct request *rq)
281{
282 INIT_LIST_HEAD(&rq->queuelist);
Jens Axboeff856ba2006-01-09 16:02:34 +0100283 INIT_LIST_HEAD(&rq->donelist);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284
285 rq->errors = 0;
286 rq->rq_status = RQ_ACTIVE;
287 rq->bio = rq->biotail = NULL;
Jens Axboe22e2c502005-06-27 10:55:12 +0200288 rq->ioprio = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289 rq->buffer = NULL;
290 rq->ref_count = 1;
291 rq->q = q;
292 rq->waiting = NULL;
293 rq->special = NULL;
294 rq->data_len = 0;
295 rq->data = NULL;
Mike Christie df46b9a2005-06-20 14:04:44 +0200296 rq->nr_phys_segments = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297 rq->sense = NULL;
298 rq->end_io = NULL;
299 rq->end_io_data = NULL;
Jens Axboeff856ba2006-01-09 16:02:34 +0100300 rq->completion_data = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301}
302
303/**
304 * blk_queue_ordered - does this queue support ordered writes
Tejun Heo797e7db2006-01-06 09:51:03 +0100305 * @q: the request queue
306 * @ordered: one of QUEUE_ORDERED_*
Jens Axboefddfdea2006-01-31 15:24:34 +0100307 * @prepare_flush_fn: rq setup helper for cache flush ordered writes
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308 *
309 * Description:
310 * For journalled file systems, doing ordered writes on a commit
311 * block instead of explicitly doing wait_on_buffer (which is bad
312 * for performance) can be a big win. Block drivers supporting this
313 * feature should call this function and indicate so.
314 *
315 **/
Tejun Heo797e7db2006-01-06 09:51:03 +0100316int blk_queue_ordered(request_queue_t *q, unsigned ordered,
317 prepare_flush_fn *prepare_flush_fn)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318{
Tejun Heo797e7db2006-01-06 09:51:03 +0100319 if (ordered & (QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_POSTFLUSH) &&
320 prepare_flush_fn == NULL) {
321 printk(KERN_ERR "blk_queue_ordered: prepare_flush_fn required\n");
322 return -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323 }
Tejun Heo797e7db2006-01-06 09:51:03 +0100324
325 if (ordered != QUEUE_ORDERED_NONE &&
326 ordered != QUEUE_ORDERED_DRAIN &&
327 ordered != QUEUE_ORDERED_DRAIN_FLUSH &&
328 ordered != QUEUE_ORDERED_DRAIN_FUA &&
329 ordered != QUEUE_ORDERED_TAG &&
330 ordered != QUEUE_ORDERED_TAG_FLUSH &&
331 ordered != QUEUE_ORDERED_TAG_FUA) {
332 printk(KERN_ERR "blk_queue_ordered: bad value %d\n", ordered);
333 return -EINVAL;
334 }
335
Tetsuo Takata60481b12006-01-24 10:34:36 +0100336 q->ordered = ordered;
Tejun Heo797e7db2006-01-06 09:51:03 +0100337 q->next_ordered = ordered;
338 q->prepare_flush_fn = prepare_flush_fn;
339
340 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341}
342
343EXPORT_SYMBOL(blk_queue_ordered);
344
345/**
346 * blk_queue_issue_flush_fn - set function for issuing a flush
347 * @q: the request queue
348 * @iff: the function to be called issuing the flush
349 *
350 * Description:
351 * If a driver supports issuing a flush command, the support is notified
352 * to the block layer by defining it through this call.
353 *
354 **/
355void blk_queue_issue_flush_fn(request_queue_t *q, issue_flush_fn *iff)
356{
357 q->issue_flush_fn = iff;
358}
359
360EXPORT_SYMBOL(blk_queue_issue_flush_fn);
361
362/*
363 * Cache flushing for ordered writes handling
364 */
Tejun Heo797e7db2006-01-06 09:51:03 +0100365inline unsigned blk_ordered_cur_seq(request_queue_t *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366{
Tejun Heo797e7db2006-01-06 09:51:03 +0100367 if (!q->ordseq)
368 return 0;
369 return 1 << ffz(q->ordseq);
370}
371
372unsigned blk_ordered_req_seq(struct request *rq)
373{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374 request_queue_t *q = rq->q;
375
Tejun Heo797e7db2006-01-06 09:51:03 +0100376 BUG_ON(q->ordseq == 0);
Tejun Heo8922e162005-10-20 16:23:44 +0200377
Tejun Heo797e7db2006-01-06 09:51:03 +0100378 if (rq == &q->pre_flush_rq)
379 return QUEUE_ORDSEQ_PREFLUSH;
380 if (rq == &q->bar_rq)
381 return QUEUE_ORDSEQ_BAR;
382 if (rq == &q->post_flush_rq)
383 return QUEUE_ORDSEQ_POSTFLUSH;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384
Tejun Heo797e7db2006-01-06 09:51:03 +0100385 if ((rq->flags & REQ_ORDERED_COLOR) ==
386 (q->orig_bar_rq->flags & REQ_ORDERED_COLOR))
387 return QUEUE_ORDSEQ_DRAIN;
388 else
389 return QUEUE_ORDSEQ_DONE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390}
391
Tejun Heo797e7db2006-01-06 09:51:03 +0100392void blk_ordered_complete_seq(request_queue_t *q, unsigned seq, int error)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393{
Tejun Heo797e7db2006-01-06 09:51:03 +0100394 struct request *rq;
395 int uptodate;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700396
Tejun Heo797e7db2006-01-06 09:51:03 +0100397 if (error && !q->orderr)
398 q->orderr = error;
Tejun Heo8922e162005-10-20 16:23:44 +0200399
Tejun Heo797e7db2006-01-06 09:51:03 +0100400 BUG_ON(q->ordseq & seq);
401 q->ordseq |= seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402
Tejun Heo797e7db2006-01-06 09:51:03 +0100403 if (blk_ordered_cur_seq(q) != QUEUE_ORDSEQ_DONE)
404 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405
406 /*
Tejun Heo797e7db2006-01-06 09:51:03 +0100407 * Okay, sequence complete.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408 */
Tejun Heo797e7db2006-01-06 09:51:03 +0100409 rq = q->orig_bar_rq;
410 uptodate = q->orderr ? q->orderr : 1;
411
412 q->ordseq = 0;
413
414 end_that_request_first(rq, uptodate, rq->hard_nr_sectors);
415 end_that_request_last(rq, uptodate);
416}
417
418static void pre_flush_end_io(struct request *rq, int error)
419{
420 elv_completed_request(rq->q, rq);
421 blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_PREFLUSH, error);
422}
423
424static void bar_end_io(struct request *rq, int error)
425{
426 elv_completed_request(rq->q, rq);
427 blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_BAR, error);
428}
429
430static void post_flush_end_io(struct request *rq, int error)
431{
432 elv_completed_request(rq->q, rq);
433 blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_POSTFLUSH, error);
434}
435
436static void queue_flush(request_queue_t *q, unsigned which)
437{
438 struct request *rq;
439 rq_end_io_fn *end_io;
440
441 if (which == QUEUE_ORDERED_PREFLUSH) {
442 rq = &q->pre_flush_rq;
443 end_io = pre_flush_end_io;
444 } else {
445 rq = &q->post_flush_rq;
446 end_io = post_flush_end_io;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700447 }
448
Tejun Heo797e7db2006-01-06 09:51:03 +0100449 rq_init(q, rq);
450 rq->flags = REQ_HARDBARRIER;
451 rq->elevator_private = NULL;
452 rq->rq_disk = q->bar_rq.rq_disk;
453 rq->rl = NULL;
454 rq->end_io = end_io;
455 q->prepare_flush_fn(q, rq);
456
Tejun Heo30e96562006-02-08 01:01:31 -0800457 elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
Tejun Heo797e7db2006-01-06 09:51:03 +0100458}
459
460static inline struct request *start_ordered(request_queue_t *q,
461 struct request *rq)
462{
463 q->bi_size = 0;
464 q->orderr = 0;
465 q->ordered = q->next_ordered;
466 q->ordseq |= QUEUE_ORDSEQ_STARTED;
467
Linus Torvalds1da177e2005-04-16 15:20:36 -0700468 /*
Tejun Heo797e7db2006-01-06 09:51:03 +0100469 * Prep proxy barrier request.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700470 */
Tejun Heo797e7db2006-01-06 09:51:03 +0100471 blkdev_dequeue_request(rq);
472 q->orig_bar_rq = rq;
473 rq = &q->bar_rq;
474 rq_init(q, rq);
475 rq->flags = bio_data_dir(q->orig_bar_rq->bio);
476 rq->flags |= q->ordered & QUEUE_ORDERED_FUA ? REQ_FUA : 0;
477 rq->elevator_private = NULL;
478 rq->rl = NULL;
479 init_request_from_bio(rq, q->orig_bar_rq->bio);
480 rq->end_io = bar_end_io;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481
Tejun Heo797e7db2006-01-06 09:51:03 +0100482 /*
483 * Queue ordered sequence. As we stack them at the head, we
484 * need to queue in reverse order. Note that we rely on that
485 * no fs request uses ELEVATOR_INSERT_FRONT and thus no fs
486 * request gets inbetween ordered sequence.
487 */
488 if (q->ordered & QUEUE_ORDERED_POSTFLUSH)
489 queue_flush(q, QUEUE_ORDERED_POSTFLUSH);
490 else
491 q->ordseq |= QUEUE_ORDSEQ_POSTFLUSH;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700492
Tejun Heo30e96562006-02-08 01:01:31 -0800493 elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
Tejun Heo797e7db2006-01-06 09:51:03 +0100494
495 if (q->ordered & QUEUE_ORDERED_PREFLUSH) {
496 queue_flush(q, QUEUE_ORDERED_PREFLUSH);
497 rq = &q->pre_flush_rq;
498 } else
499 q->ordseq |= QUEUE_ORDSEQ_PREFLUSH;
500
501 if ((q->ordered & QUEUE_ORDERED_TAG) || q->in_flight == 0)
502 q->ordseq |= QUEUE_ORDSEQ_DRAIN;
503 else
504 rq = NULL;
505
506 return rq;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507}
508
Tejun Heo797e7db2006-01-06 09:51:03 +0100509int blk_do_ordered(request_queue_t *q, struct request **rqp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510{
Jens Axboe9a7a67a2006-02-04 23:27:38 -0800511 struct request *rq = *rqp;
Tejun Heo797e7db2006-01-06 09:51:03 +0100512 int is_barrier = blk_fs_request(rq) && blk_barrier_rq(rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513
Tejun Heo797e7db2006-01-06 09:51:03 +0100514 if (!q->ordseq) {
515 if (!is_barrier)
516 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700517
Tejun Heo797e7db2006-01-06 09:51:03 +0100518 if (q->next_ordered != QUEUE_ORDERED_NONE) {
519 *rqp = start_ordered(q, rq);
520 return 1;
521 } else {
522 /*
523 * This can happen when the queue switches to
524 * ORDERED_NONE while this request is on it.
525 */
526 blkdev_dequeue_request(rq);
527 end_that_request_first(rq, -EOPNOTSUPP,
528 rq->hard_nr_sectors);
529 end_that_request_last(rq, -EOPNOTSUPP);
530 *rqp = NULL;
531 return 0;
532 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700534
Jens Axboe9a7a67a2006-02-04 23:27:38 -0800535 /*
536 * Ordered sequence in progress
537 */
538
539 /* Special requests are not subject to ordering rules. */
540 if (!blk_fs_request(rq) &&
541 rq != &q->pre_flush_rq && rq != &q->post_flush_rq)
542 return 1;
543
Tejun Heo797e7db2006-01-06 09:51:03 +0100544 if (q->ordered & QUEUE_ORDERED_TAG) {
Jens Axboe9a7a67a2006-02-04 23:27:38 -0800545 /* Ordered by tag. Blocking the next barrier is enough. */
Tejun Heo797e7db2006-01-06 09:51:03 +0100546 if (is_barrier && rq != &q->bar_rq)
547 *rqp = NULL;
Jens Axboe9a7a67a2006-02-04 23:27:38 -0800548 } else {
549 /* Ordered by draining. Wait for turn. */
550 WARN_ON(blk_ordered_req_seq(rq) < blk_ordered_cur_seq(q));
551 if (blk_ordered_req_seq(rq) > blk_ordered_cur_seq(q))
552 *rqp = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553 }
554
555 return 1;
556}
557
Tejun Heo797e7db2006-01-06 09:51:03 +0100558static int flush_dry_bio_endio(struct bio *bio, unsigned int bytes, int error)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700559{
Tejun Heo797e7db2006-01-06 09:51:03 +0100560 request_queue_t *q = bio->bi_private;
561 struct bio_vec *bvec;
562 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700563
Tejun Heo797e7db2006-01-06 09:51:03 +0100564 /*
565 * This is dry run, restore bio_sector and size. We'll finish
566 * this request again with the original bi_end_io after an
567 * error occurs or post flush is complete.
568 */
569 q->bi_size += bytes;
570
571 if (bio->bi_size)
572 return 1;
573
574 /* Rewind bvec's */
575 bio->bi_idx = 0;
576 bio_for_each_segment(bvec, bio, i) {
577 bvec->bv_len += bvec->bv_offset;
578 bvec->bv_offset = 0;
579 }
580
581 /* Reset bio */
582 set_bit(BIO_UPTODATE, &bio->bi_flags);
583 bio->bi_size = q->bi_size;
584 bio->bi_sector -= (q->bi_size >> 9);
585 q->bi_size = 0;
586
587 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700588}
Tejun Heo797e7db2006-01-06 09:51:03 +0100589
590static inline int ordered_bio_endio(struct request *rq, struct bio *bio,
591 unsigned int nbytes, int error)
592{
593 request_queue_t *q = rq->q;
594 bio_end_io_t *endio;
595 void *private;
596
597 if (&q->bar_rq != rq)
598 return 0;
599
600 /*
601 * Okay, this is the barrier request in progress, dry finish it.
602 */
603 if (error && !q->orderr)
604 q->orderr = error;
605
606 endio = bio->bi_end_io;
607 private = bio->bi_private;
608 bio->bi_end_io = flush_dry_bio_endio;
609 bio->bi_private = q;
610
611 bio_endio(bio, nbytes, error);
612
613 bio->bi_end_io = endio;
614 bio->bi_private = private;
615
616 return 1;
617}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700618
619/**
620 * blk_queue_bounce_limit - set bounce buffer limit for queue
621 * @q: the request queue for the device
622 * @dma_addr: bus address limit
623 *
624 * Description:
625 * Different hardware can have different requirements as to what pages
626 * it can do I/O directly to. A low level driver can call
627 * blk_queue_bounce_limit to have lower memory pages allocated as bounce
Andi Kleen5ee1af92006-03-08 17:57:26 -0800628 * buffers for doing I/O to pages residing above @page.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700629 **/
630void blk_queue_bounce_limit(request_queue_t *q, u64 dma_addr)
631{
632 unsigned long bounce_pfn = dma_addr >> PAGE_SHIFT;
Andi Kleen5ee1af92006-03-08 17:57:26 -0800633 int dma = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700634
Andi Kleen5ee1af92006-03-08 17:57:26 -0800635 q->bounce_gfp = GFP_NOIO;
636#if BITS_PER_LONG == 64
637 /* Assume anything <= 4GB can be handled by IOMMU.
638 Actually some IOMMUs can handle everything, but I don't
639 know of a way to test this here. */
Andi Kleen82697302006-06-21 14:48:09 +0200640 if (bounce_pfn < (min_t(u64,0xffffffff,BLK_BOUNCE_HIGH) >> PAGE_SHIFT))
Andi Kleen5ee1af92006-03-08 17:57:26 -0800641 dma = 1;
642 q->bounce_pfn = max_low_pfn;
643#else
644 if (bounce_pfn < blk_max_low_pfn)
645 dma = 1;
646 q->bounce_pfn = bounce_pfn;
647#endif
648 if (dma) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700649 init_emergency_isa_pool();
650 q->bounce_gfp = GFP_NOIO | GFP_DMA;
Andi Kleen5ee1af92006-03-08 17:57:26 -0800651 q->bounce_pfn = bounce_pfn;
652 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653}
654
655EXPORT_SYMBOL(blk_queue_bounce_limit);
656
657/**
658 * blk_queue_max_sectors - set max sectors for a request for this queue
659 * @q: the request queue for the device
660 * @max_sectors: max sectors in the usual 512b unit
661 *
662 * Description:
663 * Enables a low level driver to set an upper limit on the size of
664 * received requests.
665 **/
Jens Axboe2cb2e142006-01-17 09:04:32 +0100666void blk_queue_max_sectors(request_queue_t *q, unsigned int max_sectors)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700667{
668 if ((max_sectors << 9) < PAGE_CACHE_SIZE) {
669 max_sectors = 1 << (PAGE_CACHE_SHIFT - 9);
670 printk("%s: set to minimum %d\n", __FUNCTION__, max_sectors);
671 }
672
Mike Christiedefd94b2005-12-05 02:37:06 -0600673 if (BLK_DEF_MAX_SECTORS > max_sectors)
674 q->max_hw_sectors = q->max_sectors = max_sectors;
675 else {
676 q->max_sectors = BLK_DEF_MAX_SECTORS;
677 q->max_hw_sectors = max_sectors;
678 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679}
680
681EXPORT_SYMBOL(blk_queue_max_sectors);
682
683/**
684 * blk_queue_max_phys_segments - set max phys segments for a request for this queue
685 * @q: the request queue for the device
686 * @max_segments: max number of segments
687 *
688 * Description:
689 * Enables a low level driver to set an upper limit on the number of
690 * physical data segments in a request. This would be the largest sized
691 * scatter list the driver could handle.
692 **/
693void blk_queue_max_phys_segments(request_queue_t *q, unsigned short max_segments)
694{
695 if (!max_segments) {
696 max_segments = 1;
697 printk("%s: set to minimum %d\n", __FUNCTION__, max_segments);
698 }
699
700 q->max_phys_segments = max_segments;
701}
702
703EXPORT_SYMBOL(blk_queue_max_phys_segments);
704
705/**
706 * blk_queue_max_hw_segments - set max hw segments for a request for this queue
707 * @q: the request queue for the device
708 * @max_segments: max number of segments
709 *
710 * Description:
711 * Enables a low level driver to set an upper limit on the number of
712 * hw data segments in a request. This would be the largest number of
713 * address/length pairs the host adapter can actually give as once
714 * to the device.
715 **/
716void blk_queue_max_hw_segments(request_queue_t *q, unsigned short max_segments)
717{
718 if (!max_segments) {
719 max_segments = 1;
720 printk("%s: set to minimum %d\n", __FUNCTION__, max_segments);
721 }
722
723 q->max_hw_segments = max_segments;
724}
725
726EXPORT_SYMBOL(blk_queue_max_hw_segments);
727
728/**
729 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
730 * @q: the request queue for the device
731 * @max_size: max size of segment in bytes
732 *
733 * Description:
734 * Enables a low level driver to set an upper limit on the size of a
735 * coalesced segment
736 **/
737void blk_queue_max_segment_size(request_queue_t *q, unsigned int max_size)
738{
739 if (max_size < PAGE_CACHE_SIZE) {
740 max_size = PAGE_CACHE_SIZE;
741 printk("%s: set to minimum %d\n", __FUNCTION__, max_size);
742 }
743
744 q->max_segment_size = max_size;
745}
746
747EXPORT_SYMBOL(blk_queue_max_segment_size);
748
749/**
750 * blk_queue_hardsect_size - set hardware sector size for the queue
751 * @q: the request queue for the device
752 * @size: the hardware sector size, in bytes
753 *
754 * Description:
755 * This should typically be set to the lowest possible sector size
756 * that the hardware can operate on (possible without reverting to
757 * even internal read-modify-write operations). Usually the default
758 * of 512 covers most hardware.
759 **/
760void blk_queue_hardsect_size(request_queue_t *q, unsigned short size)
761{
762 q->hardsect_size = size;
763}
764
765EXPORT_SYMBOL(blk_queue_hardsect_size);
766
767/*
768 * Returns the minimum that is _not_ zero, unless both are zero.
769 */
770#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
771
772/**
773 * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
774 * @t: the stacking driver (top)
775 * @b: the underlying device (bottom)
776 **/
777void blk_queue_stack_limits(request_queue_t *t, request_queue_t *b)
778{
779 /* zero is "infinity" */
Mike Christiedefd94b2005-12-05 02:37:06 -0600780 t->max_sectors = min_not_zero(t->max_sectors,b->max_sectors);
781 t->max_hw_sectors = min_not_zero(t->max_hw_sectors,b->max_hw_sectors);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700782
783 t->max_phys_segments = min(t->max_phys_segments,b->max_phys_segments);
784 t->max_hw_segments = min(t->max_hw_segments,b->max_hw_segments);
785 t->max_segment_size = min(t->max_segment_size,b->max_segment_size);
786 t->hardsect_size = max(t->hardsect_size,b->hardsect_size);
NeilBrown89e5c8b2006-03-27 01:18:02 -0800787 if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags))
788 clear_bit(QUEUE_FLAG_CLUSTER, &t->queue_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789}
790
791EXPORT_SYMBOL(blk_queue_stack_limits);
792
793/**
794 * blk_queue_segment_boundary - set boundary rules for segment merging
795 * @q: the request queue for the device
796 * @mask: the memory boundary mask
797 **/
798void blk_queue_segment_boundary(request_queue_t *q, unsigned long mask)
799{
800 if (mask < PAGE_CACHE_SIZE - 1) {
801 mask = PAGE_CACHE_SIZE - 1;
802 printk("%s: set to minimum %lx\n", __FUNCTION__, mask);
803 }
804
805 q->seg_boundary_mask = mask;
806}
807
808EXPORT_SYMBOL(blk_queue_segment_boundary);
809
810/**
811 * blk_queue_dma_alignment - set dma length and memory alignment
812 * @q: the request queue for the device
813 * @mask: alignment mask
814 *
815 * description:
816 * set required memory and length aligment for direct dma transactions.
817 * this is used when buiding direct io requests for the queue.
818 *
819 **/
820void blk_queue_dma_alignment(request_queue_t *q, int mask)
821{
822 q->dma_alignment = mask;
823}
824
825EXPORT_SYMBOL(blk_queue_dma_alignment);
826
827/**
828 * blk_queue_find_tag - find a request by its tag and queue
Linus Torvalds1da177e2005-04-16 15:20:36 -0700829 * @q: The request queue for the device
830 * @tag: The tag of the request
831 *
832 * Notes:
833 * Should be used when a device returns a tag and you want to match
834 * it with a request.
835 *
836 * no locks need be held.
837 **/
838struct request *blk_queue_find_tag(request_queue_t *q, int tag)
839{
840 struct blk_queue_tag *bqt = q->queue_tags;
841
Tejun Heoba025082005-08-05 13:28:11 -0700842 if (unlikely(bqt == NULL || tag >= bqt->real_max_depth))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700843 return NULL;
844
845 return bqt->tag_index[tag];
846}
847
848EXPORT_SYMBOL(blk_queue_find_tag);
849
850/**
851 * __blk_queue_free_tags - release tag maintenance info
852 * @q: the request queue for the device
853 *
854 * Notes:
855 * blk_cleanup_queue() will take care of calling this function, if tagging
856 * has been used. So there's no need to call this directly.
857 **/
858static void __blk_queue_free_tags(request_queue_t *q)
859{
860 struct blk_queue_tag *bqt = q->queue_tags;
861
862 if (!bqt)
863 return;
864
865 if (atomic_dec_and_test(&bqt->refcnt)) {
866 BUG_ON(bqt->busy);
867 BUG_ON(!list_empty(&bqt->busy_list));
868
869 kfree(bqt->tag_index);
870 bqt->tag_index = NULL;
871
872 kfree(bqt->tag_map);
873 bqt->tag_map = NULL;
874
875 kfree(bqt);
876 }
877
878 q->queue_tags = NULL;
879 q->queue_flags &= ~(1 << QUEUE_FLAG_QUEUED);
880}
881
882/**
883 * blk_queue_free_tags - release tag maintenance info
884 * @q: the request queue for the device
885 *
886 * Notes:
887 * This is used to disabled tagged queuing to a device, yet leave
888 * queue in function.
889 **/
890void blk_queue_free_tags(request_queue_t *q)
891{
892 clear_bit(QUEUE_FLAG_QUEUED, &q->queue_flags);
893}
894
895EXPORT_SYMBOL(blk_queue_free_tags);
896
897static int
898init_tag_map(request_queue_t *q, struct blk_queue_tag *tags, int depth)
899{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700900 struct request **tag_index;
901 unsigned long *tag_map;
Tejun Heofa72b902005-06-23 00:08:49 -0700902 int nr_ulongs;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700903
904 if (depth > q->nr_requests * 2) {
905 depth = q->nr_requests * 2;
906 printk(KERN_ERR "%s: adjusted depth to %d\n",
907 __FUNCTION__, depth);
908 }
909
Jens Axboef68110f2006-03-08 13:31:44 +0100910 tag_index = kzalloc(depth * sizeof(struct request *), GFP_ATOMIC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700911 if (!tag_index)
912 goto fail;
913
Tejun Heof7d37d02005-06-23 00:08:50 -0700914 nr_ulongs = ALIGN(depth, BITS_PER_LONG) / BITS_PER_LONG;
Jens Axboef68110f2006-03-08 13:31:44 +0100915 tag_map = kzalloc(nr_ulongs * sizeof(unsigned long), GFP_ATOMIC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700916 if (!tag_map)
917 goto fail;
918
Tejun Heoba025082005-08-05 13:28:11 -0700919 tags->real_max_depth = depth;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700920 tags->max_depth = depth;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921 tags->tag_index = tag_index;
922 tags->tag_map = tag_map;
923
Linus Torvalds1da177e2005-04-16 15:20:36 -0700924 return 0;
925fail:
926 kfree(tag_index);
927 return -ENOMEM;
928}
929
930/**
931 * blk_queue_init_tags - initialize the queue tag info
932 * @q: the request queue for the device
933 * @depth: the maximum queue depth supported
934 * @tags: the tag to use
935 **/
936int blk_queue_init_tags(request_queue_t *q, int depth,
937 struct blk_queue_tag *tags)
938{
939 int rc;
940
941 BUG_ON(tags && q->queue_tags && tags != q->queue_tags);
942
943 if (!tags && !q->queue_tags) {
944 tags = kmalloc(sizeof(struct blk_queue_tag), GFP_ATOMIC);
945 if (!tags)
946 goto fail;
947
948 if (init_tag_map(q, tags, depth))
949 goto fail;
950
951 INIT_LIST_HEAD(&tags->busy_list);
952 tags->busy = 0;
953 atomic_set(&tags->refcnt, 1);
954 } else if (q->queue_tags) {
955 if ((rc = blk_queue_resize_tags(q, depth)))
956 return rc;
957 set_bit(QUEUE_FLAG_QUEUED, &q->queue_flags);
958 return 0;
959 } else
960 atomic_inc(&tags->refcnt);
961
962 /*
963 * assign it, all done
964 */
965 q->queue_tags = tags;
966 q->queue_flags |= (1 << QUEUE_FLAG_QUEUED);
967 return 0;
968fail:
969 kfree(tags);
970 return -ENOMEM;
971}
972
973EXPORT_SYMBOL(blk_queue_init_tags);
974
975/**
976 * blk_queue_resize_tags - change the queueing depth
977 * @q: the request queue for the device
978 * @new_depth: the new max command queueing depth
979 *
980 * Notes:
981 * Must be called with the queue lock held.
982 **/
983int blk_queue_resize_tags(request_queue_t *q, int new_depth)
984{
985 struct blk_queue_tag *bqt = q->queue_tags;
986 struct request **tag_index;
987 unsigned long *tag_map;
Tejun Heofa72b902005-06-23 00:08:49 -0700988 int max_depth, nr_ulongs;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700989
990 if (!bqt)
991 return -ENXIO;
992
993 /*
Tejun Heoba025082005-08-05 13:28:11 -0700994 * if we already have large enough real_max_depth. just
995 * adjust max_depth. *NOTE* as requests with tag value
996 * between new_depth and real_max_depth can be in-flight, tag
997 * map can not be shrunk blindly here.
998 */
999 if (new_depth <= bqt->real_max_depth) {
1000 bqt->max_depth = new_depth;
1001 return 0;
1002 }
1003
1004 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001005 * save the old state info, so we can copy it back
1006 */
1007 tag_index = bqt->tag_index;
1008 tag_map = bqt->tag_map;
Tejun Heoba025082005-08-05 13:28:11 -07001009 max_depth = bqt->real_max_depth;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001010
1011 if (init_tag_map(q, bqt, new_depth))
1012 return -ENOMEM;
1013
1014 memcpy(bqt->tag_index, tag_index, max_depth * sizeof(struct request *));
Tejun Heof7d37d02005-06-23 00:08:50 -07001015 nr_ulongs = ALIGN(max_depth, BITS_PER_LONG) / BITS_PER_LONG;
Tejun Heofa72b902005-06-23 00:08:49 -07001016 memcpy(bqt->tag_map, tag_map, nr_ulongs * sizeof(unsigned long));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001017
1018 kfree(tag_index);
1019 kfree(tag_map);
1020 return 0;
1021}
1022
1023EXPORT_SYMBOL(blk_queue_resize_tags);
1024
1025/**
1026 * blk_queue_end_tag - end tag operations for a request
1027 * @q: the request queue for the device
1028 * @rq: the request that has completed
1029 *
1030 * Description:
1031 * Typically called when end_that_request_first() returns 0, meaning
1032 * all transfers have been done for a request. It's important to call
1033 * this function before end_that_request_last(), as that will put the
1034 * request back on the free list thus corrupting the internal tag list.
1035 *
1036 * Notes:
1037 * queue lock must be held.
1038 **/
1039void blk_queue_end_tag(request_queue_t *q, struct request *rq)
1040{
1041 struct blk_queue_tag *bqt = q->queue_tags;
1042 int tag = rq->tag;
1043
1044 BUG_ON(tag == -1);
1045
Tejun Heoba025082005-08-05 13:28:11 -07001046 if (unlikely(tag >= bqt->real_max_depth))
Tejun Heo040c9282005-06-23 00:08:51 -07001047 /*
1048 * This can happen after tag depth has been reduced.
1049 * FIXME: how about a warning or info message here?
1050 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001051 return;
1052
1053 if (unlikely(!__test_and_clear_bit(tag, bqt->tag_map))) {
Tejun Heo040c9282005-06-23 00:08:51 -07001054 printk(KERN_ERR "%s: attempt to clear non-busy tag (%d)\n",
1055 __FUNCTION__, tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001056 return;
1057 }
1058
1059 list_del_init(&rq->queuelist);
1060 rq->flags &= ~REQ_QUEUED;
1061 rq->tag = -1;
1062
1063 if (unlikely(bqt->tag_index[tag] == NULL))
Tejun Heo040c9282005-06-23 00:08:51 -07001064 printk(KERN_ERR "%s: tag %d is missing\n",
1065 __FUNCTION__, tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001066
1067 bqt->tag_index[tag] = NULL;
1068 bqt->busy--;
1069}
1070
1071EXPORT_SYMBOL(blk_queue_end_tag);
1072
1073/**
1074 * blk_queue_start_tag - find a free tag and assign it
1075 * @q: the request queue for the device
1076 * @rq: the block request that needs tagging
1077 *
1078 * Description:
1079 * This can either be used as a stand-alone helper, or possibly be
1080 * assigned as the queue &prep_rq_fn (in which case &struct request
1081 * automagically gets a tag assigned). Note that this function
1082 * assumes that any type of request can be queued! if this is not
1083 * true for your device, you must check the request type before
1084 * calling this function. The request will also be removed from
1085 * the request queue, so it's the drivers responsibility to readd
1086 * it if it should need to be restarted for some reason.
1087 *
1088 * Notes:
1089 * queue lock must be held.
1090 **/
1091int blk_queue_start_tag(request_queue_t *q, struct request *rq)
1092{
1093 struct blk_queue_tag *bqt = q->queue_tags;
Tejun Heo2bf0fda2005-06-23 00:08:48 -07001094 int tag;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001095
1096 if (unlikely((rq->flags & REQ_QUEUED))) {
1097 printk(KERN_ERR
Tejun Heo040c9282005-06-23 00:08:51 -07001098 "%s: request %p for device [%s] already tagged %d",
1099 __FUNCTION__, rq,
1100 rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001101 BUG();
1102 }
1103
Tejun Heo2bf0fda2005-06-23 00:08:48 -07001104 tag = find_first_zero_bit(bqt->tag_map, bqt->max_depth);
1105 if (tag >= bqt->max_depth)
1106 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001107
Linus Torvalds1da177e2005-04-16 15:20:36 -07001108 __set_bit(tag, bqt->tag_map);
1109
1110 rq->flags |= REQ_QUEUED;
1111 rq->tag = tag;
1112 bqt->tag_index[tag] = rq;
1113 blkdev_dequeue_request(rq);
1114 list_add(&rq->queuelist, &bqt->busy_list);
1115 bqt->busy++;
1116 return 0;
1117}
1118
1119EXPORT_SYMBOL(blk_queue_start_tag);
1120
1121/**
1122 * blk_queue_invalidate_tags - invalidate all pending tags
1123 * @q: the request queue for the device
1124 *
1125 * Description:
1126 * Hardware conditions may dictate a need to stop all pending requests.
1127 * In this case, we will safely clear the block side of the tag queue and
1128 * readd all requests to the request queue in the right order.
1129 *
1130 * Notes:
1131 * queue lock must be held.
1132 **/
1133void blk_queue_invalidate_tags(request_queue_t *q)
1134{
1135 struct blk_queue_tag *bqt = q->queue_tags;
1136 struct list_head *tmp, *n;
1137 struct request *rq;
1138
1139 list_for_each_safe(tmp, n, &bqt->busy_list) {
1140 rq = list_entry_rq(tmp);
1141
1142 if (rq->tag == -1) {
Tejun Heo040c9282005-06-23 00:08:51 -07001143 printk(KERN_ERR
1144 "%s: bad tag found on list\n", __FUNCTION__);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001145 list_del_init(&rq->queuelist);
1146 rq->flags &= ~REQ_QUEUED;
1147 } else
1148 blk_queue_end_tag(q, rq);
1149
1150 rq->flags &= ~REQ_STARTED;
1151 __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0);
1152 }
1153}
1154
1155EXPORT_SYMBOL(blk_queue_invalidate_tags);
1156
Arjan van de Ven64100092006-01-06 09:46:02 +01001157static const char * const rq_flags[] = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001158 "REQ_RW",
1159 "REQ_FAILFAST",
Tejun Heo8922e162005-10-20 16:23:44 +02001160 "REQ_SORTED",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001161 "REQ_SOFTBARRIER",
1162 "REQ_HARDBARRIER",
Tejun Heo797e7db2006-01-06 09:51:03 +01001163 "REQ_FUA",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001164 "REQ_CMD",
1165 "REQ_NOMERGE",
1166 "REQ_STARTED",
1167 "REQ_DONTPREP",
1168 "REQ_QUEUED",
Tejun Heocb98fc82005-10-28 08:29:39 +02001169 "REQ_ELVPRIV",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001170 "REQ_PC",
1171 "REQ_BLOCK_PC",
1172 "REQ_SENSE",
1173 "REQ_FAILED",
1174 "REQ_QUIET",
1175 "REQ_SPECIAL",
1176 "REQ_DRIVE_CMD",
1177 "REQ_DRIVE_TASK",
1178 "REQ_DRIVE_TASKFILE",
1179 "REQ_PREEMPT",
1180 "REQ_PM_SUSPEND",
1181 "REQ_PM_RESUME",
1182 "REQ_PM_SHUTDOWN",
Tejun Heo797e7db2006-01-06 09:51:03 +01001183 "REQ_ORDERED_COLOR",
Linus Torvalds1da177e2005-04-16 15:20:36 -07001184};
1185
1186void blk_dump_rq_flags(struct request *rq, char *msg)
1187{
1188 int bit;
1189
1190 printk("%s: dev %s: flags = ", msg,
1191 rq->rq_disk ? rq->rq_disk->disk_name : "?");
1192 bit = 0;
1193 do {
1194 if (rq->flags & (1 << bit))
1195 printk("%s ", rq_flags[bit]);
1196 bit++;
1197 } while (bit < __REQ_NR_BITS);
1198
1199 printk("\nsector %llu, nr/cnr %lu/%u\n", (unsigned long long)rq->sector,
1200 rq->nr_sectors,
1201 rq->current_nr_sectors);
1202 printk("bio %p, biotail %p, buffer %p, data %p, len %u\n", rq->bio, rq->biotail, rq->buffer, rq->data, rq->data_len);
1203
1204 if (rq->flags & (REQ_BLOCK_PC | REQ_PC)) {
1205 printk("cdb: ");
1206 for (bit = 0; bit < sizeof(rq->cmd); bit++)
1207 printk("%02x ", rq->cmd[bit]);
1208 printk("\n");
1209 }
1210}
1211
1212EXPORT_SYMBOL(blk_dump_rq_flags);
1213
1214void blk_recount_segments(request_queue_t *q, struct bio *bio)
1215{
1216 struct bio_vec *bv, *bvprv = NULL;
1217 int i, nr_phys_segs, nr_hw_segs, seg_size, hw_seg_size, cluster;
1218 int high, highprv = 1;
1219
1220 if (unlikely(!bio->bi_io_vec))
1221 return;
1222
1223 cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
1224 hw_seg_size = seg_size = nr_phys_segs = nr_hw_segs = 0;
1225 bio_for_each_segment(bv, bio, i) {
1226 /*
1227 * the trick here is making sure that a high page is never
1228 * considered part of another segment, since that might
1229 * change with the bounce page.
1230 */
1231 high = page_to_pfn(bv->bv_page) >= q->bounce_pfn;
1232 if (high || highprv)
1233 goto new_hw_segment;
1234 if (cluster) {
1235 if (seg_size + bv->bv_len > q->max_segment_size)
1236 goto new_segment;
1237 if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv))
1238 goto new_segment;
1239 if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv))
1240 goto new_segment;
1241 if (BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len))
1242 goto new_hw_segment;
1243
1244 seg_size += bv->bv_len;
1245 hw_seg_size += bv->bv_len;
1246 bvprv = bv;
1247 continue;
1248 }
1249new_segment:
1250 if (BIOVEC_VIRT_MERGEABLE(bvprv, bv) &&
1251 !BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len)) {
1252 hw_seg_size += bv->bv_len;
1253 } else {
1254new_hw_segment:
1255 if (hw_seg_size > bio->bi_hw_front_size)
1256 bio->bi_hw_front_size = hw_seg_size;
1257 hw_seg_size = BIOVEC_VIRT_START_SIZE(bv) + bv->bv_len;
1258 nr_hw_segs++;
1259 }
1260
1261 nr_phys_segs++;
1262 bvprv = bv;
1263 seg_size = bv->bv_len;
1264 highprv = high;
1265 }
1266 if (hw_seg_size > bio->bi_hw_back_size)
1267 bio->bi_hw_back_size = hw_seg_size;
1268 if (nr_hw_segs == 1 && hw_seg_size > bio->bi_hw_front_size)
1269 bio->bi_hw_front_size = hw_seg_size;
1270 bio->bi_phys_segments = nr_phys_segs;
1271 bio->bi_hw_segments = nr_hw_segs;
1272 bio->bi_flags |= (1 << BIO_SEG_VALID);
1273}
1274
1275
Adrian Bunk93d17d32005-06-25 14:59:10 -07001276static int blk_phys_contig_segment(request_queue_t *q, struct bio *bio,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001277 struct bio *nxt)
1278{
1279 if (!(q->queue_flags & (1 << QUEUE_FLAG_CLUSTER)))
1280 return 0;
1281
1282 if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)))
1283 return 0;
1284 if (bio->bi_size + nxt->bi_size > q->max_segment_size)
1285 return 0;
1286
1287 /*
1288 * bio and nxt are contigous in memory, check if the queue allows
1289 * these two to be merged into one
1290 */
1291 if (BIO_SEG_BOUNDARY(q, bio, nxt))
1292 return 1;
1293
1294 return 0;
1295}
1296
Adrian Bunk93d17d32005-06-25 14:59:10 -07001297static int blk_hw_contig_segment(request_queue_t *q, struct bio *bio,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001298 struct bio *nxt)
1299{
1300 if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
1301 blk_recount_segments(q, bio);
1302 if (unlikely(!bio_flagged(nxt, BIO_SEG_VALID)))
1303 blk_recount_segments(q, nxt);
1304 if (!BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)) ||
1305 BIOVEC_VIRT_OVERSIZE(bio->bi_hw_front_size + bio->bi_hw_back_size))
1306 return 0;
1307 if (bio->bi_size + nxt->bi_size > q->max_segment_size)
1308 return 0;
1309
1310 return 1;
1311}
1312
Linus Torvalds1da177e2005-04-16 15:20:36 -07001313/*
1314 * map a request to scatterlist, return number of sg entries setup. Caller
1315 * must make sure sg can hold rq->nr_phys_segments entries
1316 */
1317int blk_rq_map_sg(request_queue_t *q, struct request *rq, struct scatterlist *sg)
1318{
1319 struct bio_vec *bvec, *bvprv;
1320 struct bio *bio;
1321 int nsegs, i, cluster;
1322
1323 nsegs = 0;
1324 cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
1325
1326 /*
1327 * for each bio in rq
1328 */
1329 bvprv = NULL;
1330 rq_for_each_bio(bio, rq) {
1331 /*
1332 * for each segment in bio
1333 */
1334 bio_for_each_segment(bvec, bio, i) {
1335 int nbytes = bvec->bv_len;
1336
1337 if (bvprv && cluster) {
1338 if (sg[nsegs - 1].length + nbytes > q->max_segment_size)
1339 goto new_segment;
1340
1341 if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec))
1342 goto new_segment;
1343 if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec))
1344 goto new_segment;
1345
1346 sg[nsegs - 1].length += nbytes;
1347 } else {
1348new_segment:
1349 memset(&sg[nsegs],0,sizeof(struct scatterlist));
1350 sg[nsegs].page = bvec->bv_page;
1351 sg[nsegs].length = nbytes;
1352 sg[nsegs].offset = bvec->bv_offset;
1353
1354 nsegs++;
1355 }
1356 bvprv = bvec;
1357 } /* segments in bio */
1358 } /* bios in rq */
1359
1360 return nsegs;
1361}
1362
1363EXPORT_SYMBOL(blk_rq_map_sg);
1364
1365/*
1366 * the standard queue merge functions, can be overridden with device
1367 * specific ones if so desired
1368 */
1369
1370static inline int ll_new_mergeable(request_queue_t *q,
1371 struct request *req,
1372 struct bio *bio)
1373{
1374 int nr_phys_segs = bio_phys_segments(q, bio);
1375
1376 if (req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) {
1377 req->flags |= REQ_NOMERGE;
1378 if (req == q->last_merge)
1379 q->last_merge = NULL;
1380 return 0;
1381 }
1382
1383 /*
1384 * A hw segment is just getting larger, bump just the phys
1385 * counter.
1386 */
1387 req->nr_phys_segments += nr_phys_segs;
1388 return 1;
1389}
1390
1391static inline int ll_new_hw_segment(request_queue_t *q,
1392 struct request *req,
1393 struct bio *bio)
1394{
1395 int nr_hw_segs = bio_hw_segments(q, bio);
1396 int nr_phys_segs = bio_phys_segments(q, bio);
1397
1398 if (req->nr_hw_segments + nr_hw_segs > q->max_hw_segments
1399 || req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) {
1400 req->flags |= REQ_NOMERGE;
1401 if (req == q->last_merge)
1402 q->last_merge = NULL;
1403 return 0;
1404 }
1405
1406 /*
1407 * This will form the start of a new hw segment. Bump both
1408 * counters.
1409 */
1410 req->nr_hw_segments += nr_hw_segs;
1411 req->nr_phys_segments += nr_phys_segs;
1412 return 1;
1413}
1414
1415static int ll_back_merge_fn(request_queue_t *q, struct request *req,
1416 struct bio *bio)
1417{
Mike Christiedefd94b2005-12-05 02:37:06 -06001418 unsigned short max_sectors;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001419 int len;
1420
Mike Christiedefd94b2005-12-05 02:37:06 -06001421 if (unlikely(blk_pc_request(req)))
1422 max_sectors = q->max_hw_sectors;
1423 else
1424 max_sectors = q->max_sectors;
1425
1426 if (req->nr_sectors + bio_sectors(bio) > max_sectors) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001427 req->flags |= REQ_NOMERGE;
1428 if (req == q->last_merge)
1429 q->last_merge = NULL;
1430 return 0;
1431 }
1432 if (unlikely(!bio_flagged(req->biotail, BIO_SEG_VALID)))
1433 blk_recount_segments(q, req->biotail);
1434 if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
1435 blk_recount_segments(q, bio);
1436 len = req->biotail->bi_hw_back_size + bio->bi_hw_front_size;
1437 if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req->biotail), __BVEC_START(bio)) &&
1438 !BIOVEC_VIRT_OVERSIZE(len)) {
1439 int mergeable = ll_new_mergeable(q, req, bio);
1440
1441 if (mergeable) {
1442 if (req->nr_hw_segments == 1)
1443 req->bio->bi_hw_front_size = len;
1444 if (bio->bi_hw_segments == 1)
1445 bio->bi_hw_back_size = len;
1446 }
1447 return mergeable;
1448 }
1449
1450 return ll_new_hw_segment(q, req, bio);
1451}
1452
1453static int ll_front_merge_fn(request_queue_t *q, struct request *req,
1454 struct bio *bio)
1455{
Mike Christiedefd94b2005-12-05 02:37:06 -06001456 unsigned short max_sectors;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001457 int len;
1458
Mike Christiedefd94b2005-12-05 02:37:06 -06001459 if (unlikely(blk_pc_request(req)))
1460 max_sectors = q->max_hw_sectors;
1461 else
1462 max_sectors = q->max_sectors;
1463
1464
1465 if (req->nr_sectors + bio_sectors(bio) > max_sectors) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001466 req->flags |= REQ_NOMERGE;
1467 if (req == q->last_merge)
1468 q->last_merge = NULL;
1469 return 0;
1470 }
1471 len = bio->bi_hw_back_size + req->bio->bi_hw_front_size;
1472 if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
1473 blk_recount_segments(q, bio);
1474 if (unlikely(!bio_flagged(req->bio, BIO_SEG_VALID)))
1475 blk_recount_segments(q, req->bio);
1476 if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(req->bio)) &&
1477 !BIOVEC_VIRT_OVERSIZE(len)) {
1478 int mergeable = ll_new_mergeable(q, req, bio);
1479
1480 if (mergeable) {
1481 if (bio->bi_hw_segments == 1)
1482 bio->bi_hw_front_size = len;
1483 if (req->nr_hw_segments == 1)
1484 req->biotail->bi_hw_back_size = len;
1485 }
1486 return mergeable;
1487 }
1488
1489 return ll_new_hw_segment(q, req, bio);
1490}
1491
1492static int ll_merge_requests_fn(request_queue_t *q, struct request *req,
1493 struct request *next)
1494{
Nikita Danilovdfa1a552005-06-25 14:59:20 -07001495 int total_phys_segments;
1496 int total_hw_segments;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001497
1498 /*
1499 * First check if the either of the requests are re-queued
1500 * requests. Can't merge them if they are.
1501 */
1502 if (req->special || next->special)
1503 return 0;
1504
1505 /*
Nikita Danilovdfa1a552005-06-25 14:59:20 -07001506 * Will it become too large?
Linus Torvalds1da177e2005-04-16 15:20:36 -07001507 */
1508 if ((req->nr_sectors + next->nr_sectors) > q->max_sectors)
1509 return 0;
1510
1511 total_phys_segments = req->nr_phys_segments + next->nr_phys_segments;
1512 if (blk_phys_contig_segment(q, req->biotail, next->bio))
1513 total_phys_segments--;
1514
1515 if (total_phys_segments > q->max_phys_segments)
1516 return 0;
1517
1518 total_hw_segments = req->nr_hw_segments + next->nr_hw_segments;
1519 if (blk_hw_contig_segment(q, req->biotail, next->bio)) {
1520 int len = req->biotail->bi_hw_back_size + next->bio->bi_hw_front_size;
1521 /*
1522 * propagate the combined length to the end of the requests
1523 */
1524 if (req->nr_hw_segments == 1)
1525 req->bio->bi_hw_front_size = len;
1526 if (next->nr_hw_segments == 1)
1527 next->biotail->bi_hw_back_size = len;
1528 total_hw_segments--;
1529 }
1530
1531 if (total_hw_segments > q->max_hw_segments)
1532 return 0;
1533
1534 /* Merge is OK... */
1535 req->nr_phys_segments = total_phys_segments;
1536 req->nr_hw_segments = total_hw_segments;
1537 return 1;
1538}
1539
1540/*
1541 * "plug" the device if there are no outstanding requests: this will
1542 * force the transfer to start only after we have put all the requests
1543 * on the list.
1544 *
1545 * This is called with interrupts off and no requests on the queue and
1546 * with the queue lock held.
1547 */
1548void blk_plug_device(request_queue_t *q)
1549{
1550 WARN_ON(!irqs_disabled());
1551
1552 /*
1553 * don't plug a stopped queue, it must be paired with blk_start_queue()
1554 * which will restart the queueing
1555 */
Coywolf Qi Hunt7daac492006-04-19 10:14:49 +02001556 if (blk_queue_stopped(q))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001557 return;
1558
Jens Axboe2056a782006-03-23 20:00:26 +01001559 if (!test_and_set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001560 mod_timer(&q->unplug_timer, jiffies + q->unplug_delay);
Jens Axboe2056a782006-03-23 20:00:26 +01001561 blk_add_trace_generic(q, NULL, 0, BLK_TA_PLUG);
1562 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001563}
1564
1565EXPORT_SYMBOL(blk_plug_device);
1566
1567/*
1568 * remove the queue from the plugged list, if present. called with
1569 * queue lock held and interrupts disabled.
1570 */
1571int blk_remove_plug(request_queue_t *q)
1572{
1573 WARN_ON(!irqs_disabled());
1574
1575 if (!test_and_clear_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags))
1576 return 0;
1577
1578 del_timer(&q->unplug_timer);
1579 return 1;
1580}
1581
1582EXPORT_SYMBOL(blk_remove_plug);
1583
1584/*
1585 * remove the plug and let it rip..
1586 */
1587void __generic_unplug_device(request_queue_t *q)
1588{
Coywolf Qi Hunt7daac492006-04-19 10:14:49 +02001589 if (unlikely(blk_queue_stopped(q)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001590 return;
1591
1592 if (!blk_remove_plug(q))
1593 return;
1594
Jens Axboe22e2c502005-06-27 10:55:12 +02001595 q->request_fn(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001596}
1597EXPORT_SYMBOL(__generic_unplug_device);
1598
1599/**
1600 * generic_unplug_device - fire a request queue
1601 * @q: The &request_queue_t in question
1602 *
1603 * Description:
1604 * Linux uses plugging to build bigger requests queues before letting
1605 * the device have at them. If a queue is plugged, the I/O scheduler
1606 * is still adding and merging requests on the queue. Once the queue
1607 * gets unplugged, the request_fn defined for the queue is invoked and
1608 * transfers started.
1609 **/
1610void generic_unplug_device(request_queue_t *q)
1611{
1612 spin_lock_irq(q->queue_lock);
1613 __generic_unplug_device(q);
1614 spin_unlock_irq(q->queue_lock);
1615}
1616EXPORT_SYMBOL(generic_unplug_device);
1617
1618static void blk_backing_dev_unplug(struct backing_dev_info *bdi,
1619 struct page *page)
1620{
1621 request_queue_t *q = bdi->unplug_io_data;
1622
1623 /*
1624 * devices don't necessarily have an ->unplug_fn defined
1625 */
Jens Axboe2056a782006-03-23 20:00:26 +01001626 if (q->unplug_fn) {
1627 blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL,
1628 q->rq.count[READ] + q->rq.count[WRITE]);
1629
Linus Torvalds1da177e2005-04-16 15:20:36 -07001630 q->unplug_fn(q);
Jens Axboe2056a782006-03-23 20:00:26 +01001631 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001632}
1633
1634static void blk_unplug_work(void *data)
1635{
1636 request_queue_t *q = data;
1637
Jens Axboe2056a782006-03-23 20:00:26 +01001638 blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL,
1639 q->rq.count[READ] + q->rq.count[WRITE]);
1640
Linus Torvalds1da177e2005-04-16 15:20:36 -07001641 q->unplug_fn(q);
1642}
1643
1644static void blk_unplug_timeout(unsigned long data)
1645{
1646 request_queue_t *q = (request_queue_t *)data;
1647
Jens Axboe2056a782006-03-23 20:00:26 +01001648 blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_TIMER, NULL,
1649 q->rq.count[READ] + q->rq.count[WRITE]);
1650
Linus Torvalds1da177e2005-04-16 15:20:36 -07001651 kblockd_schedule_work(&q->unplug_work);
1652}
1653
1654/**
1655 * blk_start_queue - restart a previously stopped queue
1656 * @q: The &request_queue_t in question
1657 *
1658 * Description:
1659 * blk_start_queue() will clear the stop flag on the queue, and call
1660 * the request_fn for the queue if it was in a stopped state when
1661 * entered. Also see blk_stop_queue(). Queue lock must be held.
1662 **/
1663void blk_start_queue(request_queue_t *q)
1664{
Paolo 'Blaisorblade' Giarrussoa038e252006-06-05 12:09:01 +02001665 WARN_ON(!irqs_disabled());
1666
Linus Torvalds1da177e2005-04-16 15:20:36 -07001667 clear_bit(QUEUE_FLAG_STOPPED, &q->queue_flags);
1668
1669 /*
1670 * one level of recursion is ok and is much faster than kicking
1671 * the unplug handling
1672 */
1673 if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) {
1674 q->request_fn(q);
1675 clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags);
1676 } else {
1677 blk_plug_device(q);
1678 kblockd_schedule_work(&q->unplug_work);
1679 }
1680}
1681
1682EXPORT_SYMBOL(blk_start_queue);
1683
1684/**
1685 * blk_stop_queue - stop a queue
1686 * @q: The &request_queue_t in question
1687 *
1688 * Description:
1689 * The Linux block layer assumes that a block driver will consume all
1690 * entries on the request queue when the request_fn strategy is called.
1691 * Often this will not happen, because of hardware limitations (queue
1692 * depth settings). If a device driver gets a 'queue full' response,
1693 * or if it simply chooses not to queue more I/O at one point, it can
1694 * call this function to prevent the request_fn from being called until
1695 * the driver has signalled it's ready to go again. This happens by calling
1696 * blk_start_queue() to restart queue operations. Queue lock must be held.
1697 **/
1698void blk_stop_queue(request_queue_t *q)
1699{
1700 blk_remove_plug(q);
1701 set_bit(QUEUE_FLAG_STOPPED, &q->queue_flags);
1702}
1703EXPORT_SYMBOL(blk_stop_queue);
1704
1705/**
1706 * blk_sync_queue - cancel any pending callbacks on a queue
1707 * @q: the queue
1708 *
1709 * Description:
1710 * The block layer may perform asynchronous callback activity
1711 * on a queue, such as calling the unplug function after a timeout.
1712 * A block device may call blk_sync_queue to ensure that any
1713 * such activity is cancelled, thus allowing it to release resources
1714 * the the callbacks might use. The caller must already have made sure
1715 * that its ->make_request_fn will not re-add plugging prior to calling
1716 * this function.
1717 *
1718 */
1719void blk_sync_queue(struct request_queue *q)
1720{
1721 del_timer_sync(&q->unplug_timer);
1722 kblockd_flush();
1723}
1724EXPORT_SYMBOL(blk_sync_queue);
1725
1726/**
1727 * blk_run_queue - run a single device queue
1728 * @q: The queue to run
1729 */
1730void blk_run_queue(struct request_queue *q)
1731{
1732 unsigned long flags;
1733
1734 spin_lock_irqsave(q->queue_lock, flags);
1735 blk_remove_plug(q);
Jens Axboedac07ec2006-05-11 08:20:16 +02001736
1737 /*
1738 * Only recurse once to avoid overrunning the stack, let the unplug
1739 * handling reinvoke the handler shortly if we already got there.
1740 */
1741 if (!elv_queue_empty(q)) {
1742 if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) {
1743 q->request_fn(q);
1744 clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags);
1745 } else {
1746 blk_plug_device(q);
1747 kblockd_schedule_work(&q->unplug_work);
1748 }
1749 }
1750
Linus Torvalds1da177e2005-04-16 15:20:36 -07001751 spin_unlock_irqrestore(q->queue_lock, flags);
1752}
1753EXPORT_SYMBOL(blk_run_queue);
1754
1755/**
1756 * blk_cleanup_queue: - release a &request_queue_t when it is no longer needed
Martin Waitza5802902006-04-02 13:59:55 +02001757 * @kobj: the kobj belonging of the request queue to be released
Linus Torvalds1da177e2005-04-16 15:20:36 -07001758 *
1759 * Description:
1760 * blk_cleanup_queue is the pair to blk_init_queue() or
1761 * blk_queue_make_request(). It should be called when a request queue is
1762 * being released; typically when a block device is being de-registered.
1763 * Currently, its primary task it to free all the &struct request
1764 * structures that were allocated to the queue and the queue itself.
1765 *
1766 * Caveat:
1767 * Hopefully the low level driver will have finished any
1768 * outstanding requests first...
1769 **/
Al Viro483f4af2006-03-18 18:34:37 -05001770static void blk_release_queue(struct kobject *kobj)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001771{
Al Viro483f4af2006-03-18 18:34:37 -05001772 request_queue_t *q = container_of(kobj, struct request_queue, kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001773 struct request_list *rl = &q->rq;
1774
Linus Torvalds1da177e2005-04-16 15:20:36 -07001775 blk_sync_queue(q);
1776
1777 if (rl->rq_pool)
1778 mempool_destroy(rl->rq_pool);
1779
1780 if (q->queue_tags)
1781 __blk_queue_free_tags(q);
1782
Jens Axboe2056a782006-03-23 20:00:26 +01001783 if (q->blk_trace)
1784 blk_trace_shutdown(q);
1785
Linus Torvalds1da177e2005-04-16 15:20:36 -07001786 kmem_cache_free(requestq_cachep, q);
1787}
1788
Al Viro483f4af2006-03-18 18:34:37 -05001789void blk_put_queue(request_queue_t *q)
1790{
1791 kobject_put(&q->kobj);
1792}
1793EXPORT_SYMBOL(blk_put_queue);
1794
1795void blk_cleanup_queue(request_queue_t * q)
1796{
1797 mutex_lock(&q->sysfs_lock);
1798 set_bit(QUEUE_FLAG_DEAD, &q->queue_flags);
1799 mutex_unlock(&q->sysfs_lock);
1800
1801 if (q->elevator)
1802 elevator_exit(q->elevator);
1803
1804 blk_put_queue(q);
1805}
1806
Linus Torvalds1da177e2005-04-16 15:20:36 -07001807EXPORT_SYMBOL(blk_cleanup_queue);
1808
1809static int blk_init_free_list(request_queue_t *q)
1810{
1811 struct request_list *rl = &q->rq;
1812
1813 rl->count[READ] = rl->count[WRITE] = 0;
1814 rl->starved[READ] = rl->starved[WRITE] = 0;
Tejun Heocb98fc82005-10-28 08:29:39 +02001815 rl->elvpriv = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001816 init_waitqueue_head(&rl->wait[READ]);
1817 init_waitqueue_head(&rl->wait[WRITE]);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001818
Christoph Lameter19460892005-06-23 00:08:19 -07001819 rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
1820 mempool_free_slab, request_cachep, q->node);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001821
1822 if (!rl->rq_pool)
1823 return -ENOMEM;
1824
1825 return 0;
1826}
1827
Al Viro8267e262005-10-21 03:20:53 -04001828request_queue_t *blk_alloc_queue(gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001829{
Christoph Lameter19460892005-06-23 00:08:19 -07001830 return blk_alloc_queue_node(gfp_mask, -1);
1831}
1832EXPORT_SYMBOL(blk_alloc_queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001833
Al Viro483f4af2006-03-18 18:34:37 -05001834static struct kobj_type queue_ktype;
1835
Al Viro8267e262005-10-21 03:20:53 -04001836request_queue_t *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
Christoph Lameter19460892005-06-23 00:08:19 -07001837{
1838 request_queue_t *q;
1839
1840 q = kmem_cache_alloc_node(requestq_cachep, gfp_mask, node_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001841 if (!q)
1842 return NULL;
1843
1844 memset(q, 0, sizeof(*q));
1845 init_timer(&q->unplug_timer);
Al Viro483f4af2006-03-18 18:34:37 -05001846
1847 snprintf(q->kobj.name, KOBJ_NAME_LEN, "%s", "queue");
1848 q->kobj.ktype = &queue_ktype;
1849 kobject_init(&q->kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001850
1851 q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug;
1852 q->backing_dev_info.unplug_io_data = q;
1853
Al Viro483f4af2006-03-18 18:34:37 -05001854 mutex_init(&q->sysfs_lock);
1855
Linus Torvalds1da177e2005-04-16 15:20:36 -07001856 return q;
1857}
Christoph Lameter19460892005-06-23 00:08:19 -07001858EXPORT_SYMBOL(blk_alloc_queue_node);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001859
1860/**
1861 * blk_init_queue - prepare a request queue for use with a block device
1862 * @rfn: The function to be called to process requests that have been
1863 * placed on the queue.
1864 * @lock: Request queue spin lock
1865 *
1866 * Description:
1867 * If a block device wishes to use the standard request handling procedures,
1868 * which sorts requests and coalesces adjacent requests, then it must
1869 * call blk_init_queue(). The function @rfn will be called when there
1870 * are requests on the queue that need to be processed. If the device
1871 * supports plugging, then @rfn may not be called immediately when requests
1872 * are available on the queue, but may be called at some time later instead.
1873 * Plugged queues are generally unplugged when a buffer belonging to one
1874 * of the requests on the queue is needed, or due to memory pressure.
1875 *
1876 * @rfn is not required, or even expected, to remove all requests off the
1877 * queue, but only as many as it can handle at a time. If it does leave
1878 * requests on the queue, it is responsible for arranging that the requests
1879 * get dealt with eventually.
1880 *
1881 * The queue spin lock must be held while manipulating the requests on the
Paolo 'Blaisorblade' Giarrussoa038e252006-06-05 12:09:01 +02001882 * request queue; this lock will be taken also from interrupt context, so irq
1883 * disabling is needed for it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001884 *
1885 * Function returns a pointer to the initialized request queue, or NULL if
1886 * it didn't succeed.
1887 *
1888 * Note:
1889 * blk_init_queue() must be paired with a blk_cleanup_queue() call
1890 * when the block device is deactivated (such as at module unload).
1891 **/
Christoph Lameter19460892005-06-23 00:08:19 -07001892
Linus Torvalds1da177e2005-04-16 15:20:36 -07001893request_queue_t *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock)
1894{
Christoph Lameter19460892005-06-23 00:08:19 -07001895 return blk_init_queue_node(rfn, lock, -1);
1896}
1897EXPORT_SYMBOL(blk_init_queue);
1898
1899request_queue_t *
1900blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
1901{
1902 request_queue_t *q = blk_alloc_queue_node(GFP_KERNEL, node_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001903
1904 if (!q)
1905 return NULL;
1906
Christoph Lameter19460892005-06-23 00:08:19 -07001907 q->node = node_id;
Al Viro8669aaf2006-03-18 13:50:00 -05001908 if (blk_init_free_list(q)) {
1909 kmem_cache_free(requestq_cachep, q);
1910 return NULL;
1911 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001912
152587d2005-04-12 16:22:06 -05001913 /*
1914 * if caller didn't supply a lock, they get per-queue locking with
1915 * our embedded lock
1916 */
1917 if (!lock) {
1918 spin_lock_init(&q->__queue_lock);
1919 lock = &q->__queue_lock;
1920 }
1921
Linus Torvalds1da177e2005-04-16 15:20:36 -07001922 q->request_fn = rfn;
1923 q->back_merge_fn = ll_back_merge_fn;
1924 q->front_merge_fn = ll_front_merge_fn;
1925 q->merge_requests_fn = ll_merge_requests_fn;
1926 q->prep_rq_fn = NULL;
1927 q->unplug_fn = generic_unplug_device;
1928 q->queue_flags = (1 << QUEUE_FLAG_CLUSTER);
1929 q->queue_lock = lock;
1930
1931 blk_queue_segment_boundary(q, 0xffffffff);
1932
1933 blk_queue_make_request(q, __make_request);
1934 blk_queue_max_segment_size(q, MAX_SEGMENT_SIZE);
1935
1936 blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS);
1937 blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS);
1938
1939 /*
1940 * all done
1941 */
1942 if (!elevator_init(q, NULL)) {
1943 blk_queue_congestion_threshold(q);
1944 return q;
1945 }
1946
Al Viro8669aaf2006-03-18 13:50:00 -05001947 blk_put_queue(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001948 return NULL;
1949}
Christoph Lameter19460892005-06-23 00:08:19 -07001950EXPORT_SYMBOL(blk_init_queue_node);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001951
1952int blk_get_queue(request_queue_t *q)
1953{
Nick Pigginfde6ad22005-06-23 00:08:53 -07001954 if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) {
Al Viro483f4af2006-03-18 18:34:37 -05001955 kobject_get(&q->kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001956 return 0;
1957 }
1958
1959 return 1;
1960}
1961
1962EXPORT_SYMBOL(blk_get_queue);
1963
1964static inline void blk_free_request(request_queue_t *q, struct request *rq)
1965{
Tejun Heocb98fc82005-10-28 08:29:39 +02001966 if (rq->flags & REQ_ELVPRIV)
1967 elv_put_request(q, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001968 mempool_free(rq, q->rq.rq_pool);
1969}
1970
Jens Axboe22e2c502005-06-27 10:55:12 +02001971static inline struct request *
Tejun Heocb98fc82005-10-28 08:29:39 +02001972blk_alloc_request(request_queue_t *q, int rw, struct bio *bio,
Linus Torvalds5dd96242005-10-28 08:56:34 -07001973 int priv, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001974{
1975 struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask);
1976
1977 if (!rq)
1978 return NULL;
1979
1980 /*
1981 * first three bits are identical in rq->flags and bio->bi_rw,
1982 * see bio.h and blkdev.h
1983 */
1984 rq->flags = rw;
1985
Tejun Heocb98fc82005-10-28 08:29:39 +02001986 if (priv) {
1987 if (unlikely(elv_set_request(q, rq, bio, gfp_mask))) {
1988 mempool_free(rq, q->rq.rq_pool);
1989 return NULL;
1990 }
1991 rq->flags |= REQ_ELVPRIV;
1992 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001993
Tejun Heocb98fc82005-10-28 08:29:39 +02001994 return rq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001995}
1996
1997/*
1998 * ioc_batching returns true if the ioc is a valid batching request and
1999 * should be given priority access to a request.
2000 */
2001static inline int ioc_batching(request_queue_t *q, struct io_context *ioc)
2002{
2003 if (!ioc)
2004 return 0;
2005
2006 /*
2007 * Make sure the process is able to allocate at least 1 request
2008 * even if the batch times out, otherwise we could theoretically
2009 * lose wakeups.
2010 */
2011 return ioc->nr_batch_requests == q->nr_batching ||
2012 (ioc->nr_batch_requests > 0
2013 && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME));
2014}
2015
2016/*
2017 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
2018 * will cause the process to be a "batcher" on all queues in the system. This
2019 * is the behaviour we want though - once it gets a wakeup it should be given
2020 * a nice run.
2021 */
Adrian Bunk93d17d32005-06-25 14:59:10 -07002022static void ioc_set_batching(request_queue_t *q, struct io_context *ioc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002023{
2024 if (!ioc || ioc_batching(q, ioc))
2025 return;
2026
2027 ioc->nr_batch_requests = q->nr_batching;
2028 ioc->last_waited = jiffies;
2029}
2030
2031static void __freed_request(request_queue_t *q, int rw)
2032{
2033 struct request_list *rl = &q->rq;
2034
2035 if (rl->count[rw] < queue_congestion_off_threshold(q))
2036 clear_queue_congested(q, rw);
2037
2038 if (rl->count[rw] + 1 <= q->nr_requests) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002039 if (waitqueue_active(&rl->wait[rw]))
2040 wake_up(&rl->wait[rw]);
2041
2042 blk_clear_queue_full(q, rw);
2043 }
2044}
2045
2046/*
2047 * A request has just been released. Account for it, update the full and
2048 * congestion status, wake up any waiters. Called under q->queue_lock.
2049 */
Tejun Heocb98fc82005-10-28 08:29:39 +02002050static void freed_request(request_queue_t *q, int rw, int priv)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002051{
2052 struct request_list *rl = &q->rq;
2053
2054 rl->count[rw]--;
Tejun Heocb98fc82005-10-28 08:29:39 +02002055 if (priv)
2056 rl->elvpriv--;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002057
2058 __freed_request(q, rw);
2059
2060 if (unlikely(rl->starved[rw ^ 1]))
2061 __freed_request(q, rw ^ 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002062}
2063
2064#define blkdev_free_rq(list) list_entry((list)->next, struct request, queuelist)
2065/*
Nick Piggind6344532005-06-28 20:45:14 -07002066 * Get a free request, queue_lock must be held.
2067 * Returns NULL on failure, with queue_lock held.
2068 * Returns !NULL on success, with queue_lock *not held*.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002069 */
Jens Axboe22e2c502005-06-27 10:55:12 +02002070static struct request *get_request(request_queue_t *q, int rw, struct bio *bio,
Al Viro8267e262005-10-21 03:20:53 -04002071 gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002072{
2073 struct request *rq = NULL;
2074 struct request_list *rl = &q->rq;
Jens Axboe88ee5ef2005-11-12 11:09:12 +01002075 struct io_context *ioc = NULL;
2076 int may_queue, priv;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002077
Jens Axboe88ee5ef2005-11-12 11:09:12 +01002078 may_queue = elv_may_queue(q, rw, bio);
2079 if (may_queue == ELV_MQUEUE_NO)
2080 goto rq_starved;
2081
2082 if (rl->count[rw]+1 >= queue_congestion_on_threshold(q)) {
2083 if (rl->count[rw]+1 >= q->nr_requests) {
2084 ioc = current_io_context(GFP_ATOMIC);
2085 /*
2086 * The queue will fill after this allocation, so set
2087 * it as full, and mark this process as "batching".
2088 * This process will be allowed to complete a batch of
2089 * requests, others will be blocked.
2090 */
2091 if (!blk_queue_full(q, rw)) {
2092 ioc_set_batching(q, ioc);
2093 blk_set_queue_full(q, rw);
2094 } else {
2095 if (may_queue != ELV_MQUEUE_MUST
2096 && !ioc_batching(q, ioc)) {
2097 /*
2098 * The queue is full and the allocating
2099 * process is not a "batcher", and not
2100 * exempted by the IO scheduler
2101 */
2102 goto out;
2103 }
2104 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002105 }
Jens Axboe88ee5ef2005-11-12 11:09:12 +01002106 set_queue_congested(q, rw);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002107 }
2108
Jens Axboe082cf692005-06-28 16:35:11 +02002109 /*
2110 * Only allow batching queuers to allocate up to 50% over the defined
2111 * limit of requests, otherwise we could have thousands of requests
2112 * allocated with any setting of ->nr_requests
2113 */
Hugh Dickinsfd782a42005-06-29 15:15:40 +01002114 if (rl->count[rw] >= (3 * q->nr_requests / 2))
Jens Axboe082cf692005-06-28 16:35:11 +02002115 goto out;
Hugh Dickinsfd782a42005-06-29 15:15:40 +01002116
Linus Torvalds1da177e2005-04-16 15:20:36 -07002117 rl->count[rw]++;
2118 rl->starved[rw] = 0;
Tejun Heocb98fc82005-10-28 08:29:39 +02002119
Jens Axboe64521d12005-10-28 08:30:39 +02002120 priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
Tejun Heocb98fc82005-10-28 08:29:39 +02002121 if (priv)
2122 rl->elvpriv++;
2123
Linus Torvalds1da177e2005-04-16 15:20:36 -07002124 spin_unlock_irq(q->queue_lock);
2125
Tejun Heocb98fc82005-10-28 08:29:39 +02002126 rq = blk_alloc_request(q, rw, bio, priv, gfp_mask);
Jens Axboe88ee5ef2005-11-12 11:09:12 +01002127 if (unlikely(!rq)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002128 /*
2129 * Allocation failed presumably due to memory. Undo anything
2130 * we might have messed up.
2131 *
2132 * Allocating task should really be put onto the front of the
2133 * wait queue, but this is pretty rare.
2134 */
2135 spin_lock_irq(q->queue_lock);
Tejun Heocb98fc82005-10-28 08:29:39 +02002136 freed_request(q, rw, priv);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002137
2138 /*
2139 * in the very unlikely event that allocation failed and no
2140 * requests for this direction was pending, mark us starved
2141 * so that freeing of a request in the other direction will
2142 * notice us. another possible fix would be to split the
2143 * rq mempool into READ and WRITE
2144 */
2145rq_starved:
2146 if (unlikely(rl->count[rw] == 0))
2147 rl->starved[rw] = 1;
2148
Linus Torvalds1da177e2005-04-16 15:20:36 -07002149 goto out;
2150 }
2151
Jens Axboe88ee5ef2005-11-12 11:09:12 +01002152 /*
2153 * ioc may be NULL here, and ioc_batching will be false. That's
2154 * OK, if the queue is under the request limit then requests need
2155 * not count toward the nr_batch_requests limit. There will always
2156 * be some limit enforced by BLK_BATCH_TIME.
2157 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002158 if (ioc_batching(q, ioc))
2159 ioc->nr_batch_requests--;
2160
2161 rq_init(q, rq);
2162 rq->rl = rl;
Jens Axboe2056a782006-03-23 20:00:26 +01002163
2164 blk_add_trace_generic(q, bio, rw, BLK_TA_GETRQ);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002165out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002166 return rq;
2167}
2168
2169/*
2170 * No available requests for this queue, unplug the device and wait for some
2171 * requests to become available.
Nick Piggind6344532005-06-28 20:45:14 -07002172 *
2173 * Called with q->queue_lock held, and returns with it unlocked.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002174 */
Jens Axboe22e2c502005-06-27 10:55:12 +02002175static struct request *get_request_wait(request_queue_t *q, int rw,
2176 struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002177{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002178 struct request *rq;
2179
Nick Piggin450991b2005-06-28 20:45:13 -07002180 rq = get_request(q, rw, bio, GFP_NOIO);
2181 while (!rq) {
2182 DEFINE_WAIT(wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002183 struct request_list *rl = &q->rq;
2184
2185 prepare_to_wait_exclusive(&rl->wait[rw], &wait,
2186 TASK_UNINTERRUPTIBLE);
2187
Jens Axboe22e2c502005-06-27 10:55:12 +02002188 rq = get_request(q, rw, bio, GFP_NOIO);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002189
2190 if (!rq) {
2191 struct io_context *ioc;
2192
Jens Axboe2056a782006-03-23 20:00:26 +01002193 blk_add_trace_generic(q, bio, rw, BLK_TA_SLEEPRQ);
2194
Nick Piggind6344532005-06-28 20:45:14 -07002195 __generic_unplug_device(q);
2196 spin_unlock_irq(q->queue_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002197 io_schedule();
2198
2199 /*
2200 * After sleeping, we become a "batching" process and
2201 * will be able to allocate at least one request, and
2202 * up to a big batch of them for a small period time.
2203 * See ioc_batching, ioc_set_batching
2204 */
Nick Pigginfb3cc432005-06-28 20:45:15 -07002205 ioc = current_io_context(GFP_NOIO);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002206 ioc_set_batching(q, ioc);
Nick Piggind6344532005-06-28 20:45:14 -07002207
2208 spin_lock_irq(q->queue_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002209 }
2210 finish_wait(&rl->wait[rw], &wait);
Nick Piggin450991b2005-06-28 20:45:13 -07002211 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002212
2213 return rq;
2214}
2215
Al Viro8267e262005-10-21 03:20:53 -04002216struct request *blk_get_request(request_queue_t *q, int rw, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002217{
2218 struct request *rq;
2219
2220 BUG_ON(rw != READ && rw != WRITE);
2221
Nick Piggind6344532005-06-28 20:45:14 -07002222 spin_lock_irq(q->queue_lock);
2223 if (gfp_mask & __GFP_WAIT) {
Jens Axboe22e2c502005-06-27 10:55:12 +02002224 rq = get_request_wait(q, rw, NULL);
Nick Piggind6344532005-06-28 20:45:14 -07002225 } else {
Jens Axboe22e2c502005-06-27 10:55:12 +02002226 rq = get_request(q, rw, NULL, gfp_mask);
Nick Piggind6344532005-06-28 20:45:14 -07002227 if (!rq)
2228 spin_unlock_irq(q->queue_lock);
2229 }
2230 /* q->queue_lock is unlocked at this point */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002231
2232 return rq;
2233}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002234EXPORT_SYMBOL(blk_get_request);
2235
2236/**
2237 * blk_requeue_request - put a request back on queue
2238 * @q: request queue where request should be inserted
2239 * @rq: request to be inserted
2240 *
2241 * Description:
2242 * Drivers often keep queueing requests until the hardware cannot accept
2243 * more, when that condition happens we need to put the request back
2244 * on the queue. Must be called with queue lock held.
2245 */
2246void blk_requeue_request(request_queue_t *q, struct request *rq)
2247{
Jens Axboe2056a782006-03-23 20:00:26 +01002248 blk_add_trace_rq(q, rq, BLK_TA_REQUEUE);
2249
Linus Torvalds1da177e2005-04-16 15:20:36 -07002250 if (blk_rq_tagged(rq))
2251 blk_queue_end_tag(q, rq);
2252
2253 elv_requeue_request(q, rq);
2254}
2255
2256EXPORT_SYMBOL(blk_requeue_request);
2257
2258/**
2259 * blk_insert_request - insert a special request in to a request queue
2260 * @q: request queue where request should be inserted
2261 * @rq: request to be inserted
2262 * @at_head: insert request at head or tail of queue
2263 * @data: private data
Linus Torvalds1da177e2005-04-16 15:20:36 -07002264 *
2265 * Description:
2266 * Many block devices need to execute commands asynchronously, so they don't
2267 * block the whole kernel from preemption during request execution. This is
2268 * accomplished normally by inserting aritficial requests tagged as
2269 * REQ_SPECIAL in to the corresponding request queue, and letting them be
2270 * scheduled for actual execution by the request queue.
2271 *
2272 * We have the option of inserting the head or the tail of the queue.
2273 * Typically we use the tail for new ioctls and so forth. We use the head
2274 * of the queue for things like a QUEUE_FULL message from a device, or a
2275 * host that is unable to accept a particular command.
2276 */
2277void blk_insert_request(request_queue_t *q, struct request *rq,
Tejun Heo 867d1192005-04-24 02:06:05 -05002278 int at_head, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002279{
Tejun Heo 867d1192005-04-24 02:06:05 -05002280 int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002281 unsigned long flags;
2282
2283 /*
2284 * tell I/O scheduler that this isn't a regular read/write (ie it
2285 * must not attempt merges on this) and that it acts as a soft
2286 * barrier
2287 */
2288 rq->flags |= REQ_SPECIAL | REQ_SOFTBARRIER;
2289
2290 rq->special = data;
2291
2292 spin_lock_irqsave(q->queue_lock, flags);
2293
2294 /*
2295 * If command is tagged, release the tag
2296 */
Tejun Heo 867d1192005-04-24 02:06:05 -05002297 if (blk_rq_tagged(rq))
2298 blk_queue_end_tag(q, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002299
Tejun Heo 867d1192005-04-24 02:06:05 -05002300 drive_stat_acct(rq, rq->nr_sectors, 1);
2301 __elv_add_request(q, rq, where, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002302
Linus Torvalds1da177e2005-04-16 15:20:36 -07002303 if (blk_queue_plugged(q))
2304 __generic_unplug_device(q);
2305 else
2306 q->request_fn(q);
2307 spin_unlock_irqrestore(q->queue_lock, flags);
2308}
2309
2310EXPORT_SYMBOL(blk_insert_request);
2311
2312/**
2313 * blk_rq_map_user - map user data to a request, for REQ_BLOCK_PC usage
2314 * @q: request queue where request should be inserted
Christoph Hellwig 73747ae2005-06-20 14:21:01 +02002315 * @rq: request structure to fill
Linus Torvalds1da177e2005-04-16 15:20:36 -07002316 * @ubuf: the user buffer
2317 * @len: length of user data
2318 *
2319 * Description:
2320 * Data will be mapped directly for zero copy io, if possible. Otherwise
2321 * a kernel bounce buffer is used.
2322 *
2323 * A matching blk_rq_unmap_user() must be issued at the end of io, while
2324 * still in process context.
2325 *
2326 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
2327 * before being submitted to the device, as pages mapped may be out of
2328 * reach. It's the callers responsibility to make sure this happens. The
2329 * original bio must be passed back in to blk_rq_unmap_user() for proper
2330 * unmapping.
2331 */
Jens Axboedd1cab92005-06-20 14:06:01 +02002332int blk_rq_map_user(request_queue_t *q, struct request *rq, void __user *ubuf,
2333 unsigned int len)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002334{
2335 unsigned long uaddr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002336 struct bio *bio;
Jens Axboedd1cab92005-06-20 14:06:01 +02002337 int reading;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002338
Mike Christiedefd94b2005-12-05 02:37:06 -06002339 if (len > (q->max_hw_sectors << 9))
Jens Axboedd1cab92005-06-20 14:06:01 +02002340 return -EINVAL;
2341 if (!len || !ubuf)
2342 return -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002343
Jens Axboedd1cab92005-06-20 14:06:01 +02002344 reading = rq_data_dir(rq) == READ;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002345
2346 /*
2347 * if alignment requirement is satisfied, map in user pages for
2348 * direct dma. else, set up kernel bounce buffers
2349 */
2350 uaddr = (unsigned long) ubuf;
2351 if (!(uaddr & queue_dma_alignment(q)) && !(len & queue_dma_alignment(q)))
Jens Axboedd1cab92005-06-20 14:06:01 +02002352 bio = bio_map_user(q, NULL, uaddr, len, reading);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002353 else
Jens Axboedd1cab92005-06-20 14:06:01 +02002354 bio = bio_copy_user(q, uaddr, len, reading);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002355
2356 if (!IS_ERR(bio)) {
2357 rq->bio = rq->biotail = bio;
2358 blk_rq_bio_prep(q, rq, bio);
2359
2360 rq->buffer = rq->data = NULL;
2361 rq->data_len = len;
Jens Axboedd1cab92005-06-20 14:06:01 +02002362 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002363 }
2364
2365 /*
2366 * bio is the err-ptr
2367 */
Jens Axboedd1cab92005-06-20 14:06:01 +02002368 return PTR_ERR(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002369}
2370
2371EXPORT_SYMBOL(blk_rq_map_user);
2372
2373/**
James Bottomley f1970ba2005-06-20 14:06:52 +02002374 * blk_rq_map_user_iov - map user data to a request, for REQ_BLOCK_PC usage
2375 * @q: request queue where request should be inserted
2376 * @rq: request to map data to
2377 * @iov: pointer to the iovec
2378 * @iov_count: number of elements in the iovec
2379 *
2380 * Description:
2381 * Data will be mapped directly for zero copy io, if possible. Otherwise
2382 * a kernel bounce buffer is used.
2383 *
2384 * A matching blk_rq_unmap_user() must be issued at the end of io, while
2385 * still in process context.
2386 *
2387 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
2388 * before being submitted to the device, as pages mapped may be out of
2389 * reach. It's the callers responsibility to make sure this happens. The
2390 * original bio must be passed back in to blk_rq_unmap_user() for proper
2391 * unmapping.
2392 */
2393int blk_rq_map_user_iov(request_queue_t *q, struct request *rq,
2394 struct sg_iovec *iov, int iov_count)
2395{
2396 struct bio *bio;
2397
2398 if (!iov || iov_count <= 0)
2399 return -EINVAL;
2400
2401 /* we don't allow misaligned data like bio_map_user() does. If the
2402 * user is using sg, they're expected to know the alignment constraints
2403 * and respect them accordingly */
2404 bio = bio_map_user_iov(q, NULL, iov, iov_count, rq_data_dir(rq)== READ);
2405 if (IS_ERR(bio))
2406 return PTR_ERR(bio);
2407
2408 rq->bio = rq->biotail = bio;
2409 blk_rq_bio_prep(q, rq, bio);
2410 rq->buffer = rq->data = NULL;
2411 rq->data_len = bio->bi_size;
2412 return 0;
2413}
2414
2415EXPORT_SYMBOL(blk_rq_map_user_iov);
2416
2417/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07002418 * blk_rq_unmap_user - unmap a request with user data
Christoph Hellwig 73747ae2005-06-20 14:21:01 +02002419 * @bio: bio to be unmapped
Linus Torvalds1da177e2005-04-16 15:20:36 -07002420 * @ulen: length of user buffer
2421 *
2422 * Description:
Christoph Hellwig 73747ae2005-06-20 14:21:01 +02002423 * Unmap a bio previously mapped by blk_rq_map_user().
Linus Torvalds1da177e2005-04-16 15:20:36 -07002424 */
Jens Axboedd1cab92005-06-20 14:06:01 +02002425int blk_rq_unmap_user(struct bio *bio, unsigned int ulen)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002426{
2427 int ret = 0;
2428
2429 if (bio) {
2430 if (bio_flagged(bio, BIO_USER_MAPPED))
2431 bio_unmap_user(bio);
2432 else
2433 ret = bio_uncopy_user(bio);
2434 }
2435
Jens Axboedd1cab92005-06-20 14:06:01 +02002436 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002437}
2438
2439EXPORT_SYMBOL(blk_rq_unmap_user);
2440
2441/**
Mike Christie df46b9a2005-06-20 14:04:44 +02002442 * blk_rq_map_kern - map kernel data to a request, for REQ_BLOCK_PC usage
2443 * @q: request queue where request should be inserted
Christoph Hellwig 73747ae2005-06-20 14:21:01 +02002444 * @rq: request to fill
Mike Christie df46b9a2005-06-20 14:04:44 +02002445 * @kbuf: the kernel buffer
2446 * @len: length of user data
Christoph Hellwig 73747ae2005-06-20 14:21:01 +02002447 * @gfp_mask: memory allocation flags
Mike Christie df46b9a2005-06-20 14:04:44 +02002448 */
Jens Axboedd1cab92005-06-20 14:06:01 +02002449int blk_rq_map_kern(request_queue_t *q, struct request *rq, void *kbuf,
Al Viro8267e262005-10-21 03:20:53 -04002450 unsigned int len, gfp_t gfp_mask)
Mike Christie df46b9a2005-06-20 14:04:44 +02002451{
Mike Christie df46b9a2005-06-20 14:04:44 +02002452 struct bio *bio;
2453
Mike Christiedefd94b2005-12-05 02:37:06 -06002454 if (len > (q->max_hw_sectors << 9))
Jens Axboedd1cab92005-06-20 14:06:01 +02002455 return -EINVAL;
2456 if (!len || !kbuf)
2457 return -EINVAL;
Mike Christie df46b9a2005-06-20 14:04:44 +02002458
2459 bio = bio_map_kern(q, kbuf, len, gfp_mask);
Jens Axboedd1cab92005-06-20 14:06:01 +02002460 if (IS_ERR(bio))
2461 return PTR_ERR(bio);
Mike Christie df46b9a2005-06-20 14:04:44 +02002462
Jens Axboedd1cab92005-06-20 14:06:01 +02002463 if (rq_data_dir(rq) == WRITE)
2464 bio->bi_rw |= (1 << BIO_RW);
Mike Christie df46b9a2005-06-20 14:04:44 +02002465
Jens Axboedd1cab92005-06-20 14:06:01 +02002466 rq->bio = rq->biotail = bio;
2467 blk_rq_bio_prep(q, rq, bio);
Mike Christie df46b9a2005-06-20 14:04:44 +02002468
Jens Axboedd1cab92005-06-20 14:06:01 +02002469 rq->buffer = rq->data = NULL;
2470 rq->data_len = len;
2471 return 0;
Mike Christie df46b9a2005-06-20 14:04:44 +02002472}
2473
2474EXPORT_SYMBOL(blk_rq_map_kern);
2475
Christoph Hellwig 73747ae2005-06-20 14:21:01 +02002476/**
2477 * blk_execute_rq_nowait - insert a request into queue for execution
2478 * @q: queue to insert the request in
2479 * @bd_disk: matching gendisk
2480 * @rq: request to insert
2481 * @at_head: insert request at head or tail of queue
2482 * @done: I/O completion handler
2483 *
2484 * Description:
2485 * Insert a fully prepared request at the back of the io scheduler queue
2486 * for execution. Don't wait for completion.
2487 */
James Bottomley f1970ba2005-06-20 14:06:52 +02002488void blk_execute_rq_nowait(request_queue_t *q, struct gendisk *bd_disk,
2489 struct request *rq, int at_head,
Tejun Heo8ffdc652006-01-06 09:49:03 +01002490 rq_end_io_fn *done)
James Bottomley f1970ba2005-06-20 14:06:52 +02002491{
2492 int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
2493
2494 rq->rq_disk = bd_disk;
2495 rq->flags |= REQ_NOMERGE;
2496 rq->end_io = done;
Andrew Morton4c5d0bb2006-03-22 08:08:01 +01002497 WARN_ON(irqs_disabled());
2498 spin_lock_irq(q->queue_lock);
2499 __elv_add_request(q, rq, where, 1);
2500 __generic_unplug_device(q);
2501 spin_unlock_irq(q->queue_lock);
James Bottomley f1970ba2005-06-20 14:06:52 +02002502}
Mike Christie6e39b692005-11-11 05:30:24 -06002503EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
2504
Linus Torvalds1da177e2005-04-16 15:20:36 -07002505/**
2506 * blk_execute_rq - insert a request into queue for execution
2507 * @q: queue to insert the request in
2508 * @bd_disk: matching gendisk
2509 * @rq: request to insert
James Bottomley 994ca9a2005-06-20 14:11:09 +02002510 * @at_head: insert request at head or tail of queue
Linus Torvalds1da177e2005-04-16 15:20:36 -07002511 *
2512 * Description:
2513 * Insert a fully prepared request at the back of the io scheduler queue
Christoph Hellwig 73747ae2005-06-20 14:21:01 +02002514 * for execution and wait for completion.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002515 */
2516int blk_execute_rq(request_queue_t *q, struct gendisk *bd_disk,
James Bottomley 994ca9a2005-06-20 14:11:09 +02002517 struct request *rq, int at_head)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002518{
Ingo Molnar60be6b92006-07-03 00:25:26 -07002519 DECLARE_COMPLETION_ONSTACK(wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002520 char sense[SCSI_SENSE_BUFFERSIZE];
2521 int err = 0;
2522
Linus Torvalds1da177e2005-04-16 15:20:36 -07002523 /*
2524 * we need an extra reference to the request, so we can look at
2525 * it after io completion
2526 */
2527 rq->ref_count++;
2528
2529 if (!rq->sense) {
2530 memset(sense, 0, sizeof(sense));
2531 rq->sense = sense;
2532 rq->sense_len = 0;
2533 }
2534
Linus Torvalds1da177e2005-04-16 15:20:36 -07002535 rq->waiting = &wait;
James Bottomley 994ca9a2005-06-20 14:11:09 +02002536 blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002537 wait_for_completion(&wait);
2538 rq->waiting = NULL;
2539
2540 if (rq->errors)
2541 err = -EIO;
2542
2543 return err;
2544}
2545
2546EXPORT_SYMBOL(blk_execute_rq);
2547
2548/**
2549 * blkdev_issue_flush - queue a flush
2550 * @bdev: blockdev to issue flush for
2551 * @error_sector: error sector
2552 *
2553 * Description:
2554 * Issue a flush for the block device in question. Caller can supply
2555 * room for storing the error offset in case of a flush error, if they
2556 * wish to. Caller must run wait_for_completion() on its own.
2557 */
2558int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector)
2559{
2560 request_queue_t *q;
2561
2562 if (bdev->bd_disk == NULL)
2563 return -ENXIO;
2564
2565 q = bdev_get_queue(bdev);
2566 if (!q)
2567 return -ENXIO;
2568 if (!q->issue_flush_fn)
2569 return -EOPNOTSUPP;
2570
2571 return q->issue_flush_fn(q, bdev->bd_disk, error_sector);
2572}
2573
2574EXPORT_SYMBOL(blkdev_issue_flush);
2575
Adrian Bunk93d17d32005-06-25 14:59:10 -07002576static void drive_stat_acct(struct request *rq, int nr_sectors, int new_io)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002577{
2578 int rw = rq_data_dir(rq);
2579
2580 if (!blk_fs_request(rq) || !rq->rq_disk)
2581 return;
2582
Jens Axboed72d9042005-11-01 08:35:42 +01002583 if (!new_io) {
Jens Axboea3623572005-11-01 09:26:16 +01002584 __disk_stat_inc(rq->rq_disk, merges[rw]);
Jens Axboed72d9042005-11-01 08:35:42 +01002585 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002586 disk_round_stats(rq->rq_disk);
2587 rq->rq_disk->in_flight++;
2588 }
2589}
2590
2591/*
2592 * add-request adds a request to the linked list.
2593 * queue lock is held and interrupts disabled, as we muck with the
2594 * request queue list.
2595 */
2596static inline void add_request(request_queue_t * q, struct request * req)
2597{
2598 drive_stat_acct(req, req->nr_sectors, 1);
2599
2600 if (q->activity_fn)
2601 q->activity_fn(q->activity_data, rq_data_dir(req));
2602
2603 /*
2604 * elevator indicated where it wants this request to be
2605 * inserted at elevator_merge time
2606 */
2607 __elv_add_request(q, req, ELEVATOR_INSERT_SORT, 0);
2608}
2609
2610/*
2611 * disk_round_stats() - Round off the performance stats on a struct
2612 * disk_stats.
2613 *
2614 * The average IO queue length and utilisation statistics are maintained
2615 * by observing the current state of the queue length and the amount of
2616 * time it has been in this state for.
2617 *
2618 * Normally, that accounting is done on IO completion, but that can result
2619 * in more than a second's worth of IO being accounted for within any one
2620 * second, leading to >100% utilisation. To deal with that, we call this
2621 * function to do a round-off before returning the results when reading
2622 * /proc/diskstats. This accounts immediately for all queue usage up to
2623 * the current jiffies and restarts the counters again.
2624 */
2625void disk_round_stats(struct gendisk *disk)
2626{
2627 unsigned long now = jiffies;
2628
Chen, Kenneth Wb2982642005-10-13 21:49:29 +02002629 if (now == disk->stamp)
2630 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002631
Chen, Kenneth W20e5c812005-10-13 21:48:42 +02002632 if (disk->in_flight) {
2633 __disk_stat_add(disk, time_in_queue,
2634 disk->in_flight * (now - disk->stamp));
2635 __disk_stat_add(disk, io_ticks, (now - disk->stamp));
2636 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002637 disk->stamp = now;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002638}
2639
Jun'ichi "Nick" Nomura3eaf8402006-02-01 03:04:53 -08002640EXPORT_SYMBOL_GPL(disk_round_stats);
2641
Linus Torvalds1da177e2005-04-16 15:20:36 -07002642/*
2643 * queue lock must be held
2644 */
Mike Christie6e39b692005-11-11 05:30:24 -06002645void __blk_put_request(request_queue_t *q, struct request *req)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002646{
2647 struct request_list *rl = req->rl;
2648
2649 if (unlikely(!q))
2650 return;
2651 if (unlikely(--req->ref_count))
2652 return;
2653
Tejun Heo8922e162005-10-20 16:23:44 +02002654 elv_completed_request(q, req);
2655
Linus Torvalds1da177e2005-04-16 15:20:36 -07002656 req->rq_status = RQ_INACTIVE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002657 req->rl = NULL;
2658
2659 /*
2660 * Request may not have originated from ll_rw_blk. if not,
2661 * it didn't come out of our reserved rq pools
2662 */
2663 if (rl) {
2664 int rw = rq_data_dir(req);
Tejun Heocb98fc82005-10-28 08:29:39 +02002665 int priv = req->flags & REQ_ELVPRIV;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002666
Linus Torvalds1da177e2005-04-16 15:20:36 -07002667 BUG_ON(!list_empty(&req->queuelist));
2668
2669 blk_free_request(q, req);
Tejun Heocb98fc82005-10-28 08:29:39 +02002670 freed_request(q, rw, priv);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002671 }
2672}
2673
Mike Christie6e39b692005-11-11 05:30:24 -06002674EXPORT_SYMBOL_GPL(__blk_put_request);
2675
Linus Torvalds1da177e2005-04-16 15:20:36 -07002676void blk_put_request(struct request *req)
2677{
Tejun Heo8922e162005-10-20 16:23:44 +02002678 unsigned long flags;
2679 request_queue_t *q = req->q;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002680
Tejun Heo8922e162005-10-20 16:23:44 +02002681 /*
2682 * Gee, IDE calls in w/ NULL q. Fix IDE and remove the
2683 * following if (q) test.
2684 */
2685 if (q) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002686 spin_lock_irqsave(q->queue_lock, flags);
2687 __blk_put_request(q, req);
2688 spin_unlock_irqrestore(q->queue_lock, flags);
2689 }
2690}
2691
2692EXPORT_SYMBOL(blk_put_request);
2693
2694/**
2695 * blk_end_sync_rq - executes a completion event on a request
2696 * @rq: request to complete
Jens Axboefddfdea2006-01-31 15:24:34 +01002697 * @error: end io status of the request
Linus Torvalds1da177e2005-04-16 15:20:36 -07002698 */
Tejun Heo8ffdc652006-01-06 09:49:03 +01002699void blk_end_sync_rq(struct request *rq, int error)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002700{
2701 struct completion *waiting = rq->waiting;
2702
2703 rq->waiting = NULL;
2704 __blk_put_request(rq->q, rq);
2705
2706 /*
2707 * complete last, if this is a stack request the process (and thus
2708 * the rq pointer) could be invalid right after this complete()
2709 */
2710 complete(waiting);
2711}
2712EXPORT_SYMBOL(blk_end_sync_rq);
2713
2714/**
2715 * blk_congestion_wait - wait for a queue to become uncongested
2716 * @rw: READ or WRITE
2717 * @timeout: timeout in jiffies
2718 *
2719 * Waits for up to @timeout jiffies for a queue (any queue) to exit congestion.
2720 * If no queues are congested then just wait for the next request to be
2721 * returned.
2722 */
2723long blk_congestion_wait(int rw, long timeout)
2724{
2725 long ret;
2726 DEFINE_WAIT(wait);
2727 wait_queue_head_t *wqh = &congestion_wqh[rw];
2728
2729 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
2730 ret = io_schedule_timeout(timeout);
2731 finish_wait(wqh, &wait);
2732 return ret;
2733}
2734
2735EXPORT_SYMBOL(blk_congestion_wait);
2736
2737/*
2738 * Has to be called with the request spinlock acquired
2739 */
2740static int attempt_merge(request_queue_t *q, struct request *req,
2741 struct request *next)
2742{
2743 if (!rq_mergeable(req) || !rq_mergeable(next))
2744 return 0;
2745
2746 /*
Andreas Mohrd6e05ed2006-06-26 18:35:02 +02002747 * not contiguous
Linus Torvalds1da177e2005-04-16 15:20:36 -07002748 */
2749 if (req->sector + req->nr_sectors != next->sector)
2750 return 0;
2751
2752 if (rq_data_dir(req) != rq_data_dir(next)
2753 || req->rq_disk != next->rq_disk
2754 || next->waiting || next->special)
2755 return 0;
2756
2757 /*
2758 * If we are allowed to merge, then append bio list
2759 * from next to rq and release next. merge_requests_fn
2760 * will have updated segment counts, update sector
2761 * counts here.
2762 */
2763 if (!q->merge_requests_fn(q, req, next))
2764 return 0;
2765
2766 /*
2767 * At this point we have either done a back merge
2768 * or front merge. We need the smaller start_time of
2769 * the merged requests to be the current request
2770 * for accounting purposes.
2771 */
2772 if (time_after(req->start_time, next->start_time))
2773 req->start_time = next->start_time;
2774
2775 req->biotail->bi_next = next->bio;
2776 req->biotail = next->biotail;
2777
2778 req->nr_sectors = req->hard_nr_sectors += next->hard_nr_sectors;
2779
2780 elv_merge_requests(q, req, next);
2781
2782 if (req->rq_disk) {
2783 disk_round_stats(req->rq_disk);
2784 req->rq_disk->in_flight--;
2785 }
2786
Jens Axboe22e2c502005-06-27 10:55:12 +02002787 req->ioprio = ioprio_best(req->ioprio, next->ioprio);
2788
Linus Torvalds1da177e2005-04-16 15:20:36 -07002789 __blk_put_request(q, next);
2790 return 1;
2791}
2792
2793static inline int attempt_back_merge(request_queue_t *q, struct request *rq)
2794{
2795 struct request *next = elv_latter_request(q, rq);
2796
2797 if (next)
2798 return attempt_merge(q, rq, next);
2799
2800 return 0;
2801}
2802
2803static inline int attempt_front_merge(request_queue_t *q, struct request *rq)
2804{
2805 struct request *prev = elv_former_request(q, rq);
2806
2807 if (prev)
2808 return attempt_merge(q, prev, rq);
2809
2810 return 0;
2811}
2812
Tejun Heo52d9e672006-01-06 09:49:58 +01002813static void init_request_from_bio(struct request *req, struct bio *bio)
2814{
2815 req->flags |= REQ_CMD;
2816
2817 /*
2818 * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST)
2819 */
2820 if (bio_rw_ahead(bio) || bio_failfast(bio))
2821 req->flags |= REQ_FAILFAST;
2822
2823 /*
2824 * REQ_BARRIER implies no merging, but lets make it explicit
2825 */
2826 if (unlikely(bio_barrier(bio)))
2827 req->flags |= (REQ_HARDBARRIER | REQ_NOMERGE);
2828
Jens Axboeb31dc662006-06-13 08:26:10 +02002829 if (bio_sync(bio))
2830 req->flags |= REQ_RW_SYNC;
2831
Tejun Heo52d9e672006-01-06 09:49:58 +01002832 req->errors = 0;
2833 req->hard_sector = req->sector = bio->bi_sector;
2834 req->hard_nr_sectors = req->nr_sectors = bio_sectors(bio);
2835 req->current_nr_sectors = req->hard_cur_sectors = bio_cur_sectors(bio);
2836 req->nr_phys_segments = bio_phys_segments(req->q, bio);
2837 req->nr_hw_segments = bio_hw_segments(req->q, bio);
2838 req->buffer = bio_data(bio); /* see ->buffer comment above */
2839 req->waiting = NULL;
2840 req->bio = req->biotail = bio;
2841 req->ioprio = bio_prio(bio);
2842 req->rq_disk = bio->bi_bdev->bd_disk;
2843 req->start_time = jiffies;
2844}
2845
Linus Torvalds1da177e2005-04-16 15:20:36 -07002846static int __make_request(request_queue_t *q, struct bio *bio)
2847{
Nick Piggin450991b2005-06-28 20:45:13 -07002848 struct request *req;
Jens Axboe4a534f92005-04-16 15:25:40 -07002849 int el_ret, rw, nr_sectors, cur_nr_sectors, barrier, err, sync;
Jens Axboe22e2c502005-06-27 10:55:12 +02002850 unsigned short prio;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002851 sector_t sector;
2852
2853 sector = bio->bi_sector;
2854 nr_sectors = bio_sectors(bio);
2855 cur_nr_sectors = bio_cur_sectors(bio);
Jens Axboe22e2c502005-06-27 10:55:12 +02002856 prio = bio_prio(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002857
2858 rw = bio_data_dir(bio);
Jens Axboe4a534f92005-04-16 15:25:40 -07002859 sync = bio_sync(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002860
2861 /*
2862 * low level driver can indicate that it wants pages above a
2863 * certain limit bounced to low memory (ie for highmem, or even
2864 * ISA dma in theory)
2865 */
2866 blk_queue_bounce(q, &bio);
2867
2868 spin_lock_prefetch(q->queue_lock);
2869
2870 barrier = bio_barrier(bio);
Tejun Heo797e7db2006-01-06 09:51:03 +01002871 if (unlikely(barrier) && (q->next_ordered == QUEUE_ORDERED_NONE)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002872 err = -EOPNOTSUPP;
2873 goto end_io;
2874 }
2875
Linus Torvalds1da177e2005-04-16 15:20:36 -07002876 spin_lock_irq(q->queue_lock);
2877
Nick Piggin450991b2005-06-28 20:45:13 -07002878 if (unlikely(barrier) || elv_queue_empty(q))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002879 goto get_rq;
2880
2881 el_ret = elv_merge(q, &req, bio);
2882 switch (el_ret) {
2883 case ELEVATOR_BACK_MERGE:
2884 BUG_ON(!rq_mergeable(req));
2885
2886 if (!q->back_merge_fn(q, req, bio))
2887 break;
2888
Jens Axboe2056a782006-03-23 20:00:26 +01002889 blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE);
2890
Linus Torvalds1da177e2005-04-16 15:20:36 -07002891 req->biotail->bi_next = bio;
2892 req->biotail = bio;
2893 req->nr_sectors = req->hard_nr_sectors += nr_sectors;
Jens Axboe22e2c502005-06-27 10:55:12 +02002894 req->ioprio = ioprio_best(req->ioprio, prio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002895 drive_stat_acct(req, nr_sectors, 0);
2896 if (!attempt_back_merge(q, req))
2897 elv_merged_request(q, req);
2898 goto out;
2899
2900 case ELEVATOR_FRONT_MERGE:
2901 BUG_ON(!rq_mergeable(req));
2902
2903 if (!q->front_merge_fn(q, req, bio))
2904 break;
2905
Jens Axboe2056a782006-03-23 20:00:26 +01002906 blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE);
2907
Linus Torvalds1da177e2005-04-16 15:20:36 -07002908 bio->bi_next = req->bio;
2909 req->bio = bio;
2910
2911 /*
2912 * may not be valid. if the low level driver said
2913 * it didn't need a bounce buffer then it better
2914 * not touch req->buffer either...
2915 */
2916 req->buffer = bio_data(bio);
2917 req->current_nr_sectors = cur_nr_sectors;
2918 req->hard_cur_sectors = cur_nr_sectors;
2919 req->sector = req->hard_sector = sector;
2920 req->nr_sectors = req->hard_nr_sectors += nr_sectors;
Jens Axboe22e2c502005-06-27 10:55:12 +02002921 req->ioprio = ioprio_best(req->ioprio, prio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002922 drive_stat_acct(req, nr_sectors, 0);
2923 if (!attempt_front_merge(q, req))
2924 elv_merged_request(q, req);
2925 goto out;
2926
Nick Piggin450991b2005-06-28 20:45:13 -07002927 /* ELV_NO_MERGE: elevator says don't/can't merge. */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002928 default:
Nick Piggin450991b2005-06-28 20:45:13 -07002929 ;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002930 }
2931
Linus Torvalds1da177e2005-04-16 15:20:36 -07002932get_rq:
Nick Piggin450991b2005-06-28 20:45:13 -07002933 /*
2934 * Grab a free request. This is might sleep but can not fail.
Nick Piggind6344532005-06-28 20:45:14 -07002935 * Returns with the queue unlocked.
Nick Piggin450991b2005-06-28 20:45:13 -07002936 */
Nick Piggin450991b2005-06-28 20:45:13 -07002937 req = get_request_wait(q, rw, bio);
Nick Piggind6344532005-06-28 20:45:14 -07002938
Nick Piggin450991b2005-06-28 20:45:13 -07002939 /*
2940 * After dropping the lock and possibly sleeping here, our request
2941 * may now be mergeable after it had proven unmergeable (above).
2942 * We don't worry about that case for efficiency. It won't happen
2943 * often, and the elevators are able to handle it.
2944 */
Tejun Heo52d9e672006-01-06 09:49:58 +01002945 init_request_from_bio(req, bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002946
Nick Piggin450991b2005-06-28 20:45:13 -07002947 spin_lock_irq(q->queue_lock);
2948 if (elv_queue_empty(q))
2949 blk_plug_device(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002950 add_request(q, req);
2951out:
Jens Axboe4a534f92005-04-16 15:25:40 -07002952 if (sync)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002953 __generic_unplug_device(q);
2954
2955 spin_unlock_irq(q->queue_lock);
2956 return 0;
2957
2958end_io:
2959 bio_endio(bio, nr_sectors << 9, err);
2960 return 0;
2961}
2962
2963/*
2964 * If bio->bi_dev is a partition, remap the location
2965 */
2966static inline void blk_partition_remap(struct bio *bio)
2967{
2968 struct block_device *bdev = bio->bi_bdev;
2969
2970 if (bdev != bdev->bd_contains) {
2971 struct hd_struct *p = bdev->bd_part;
Jens Axboea3623572005-11-01 09:26:16 +01002972 const int rw = bio_data_dir(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002973
Jens Axboea3623572005-11-01 09:26:16 +01002974 p->sectors[rw] += bio_sectors(bio);
2975 p->ios[rw]++;
2976
Linus Torvalds1da177e2005-04-16 15:20:36 -07002977 bio->bi_sector += p->start_sect;
2978 bio->bi_bdev = bdev->bd_contains;
2979 }
2980}
2981
Linus Torvalds1da177e2005-04-16 15:20:36 -07002982static void handle_bad_sector(struct bio *bio)
2983{
2984 char b[BDEVNAME_SIZE];
2985
2986 printk(KERN_INFO "attempt to access beyond end of device\n");
2987 printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n",
2988 bdevname(bio->bi_bdev, b),
2989 bio->bi_rw,
2990 (unsigned long long)bio->bi_sector + bio_sectors(bio),
2991 (long long)(bio->bi_bdev->bd_inode->i_size >> 9));
2992
2993 set_bit(BIO_EOF, &bio->bi_flags);
2994}
2995
2996/**
2997 * generic_make_request: hand a buffer to its device driver for I/O
2998 * @bio: The bio describing the location in memory and on the device.
2999 *
3000 * generic_make_request() is used to make I/O requests of block
3001 * devices. It is passed a &struct bio, which describes the I/O that needs
3002 * to be done.
3003 *
3004 * generic_make_request() does not return any status. The
3005 * success/failure status of the request, along with notification of
3006 * completion, is delivered asynchronously through the bio->bi_end_io
3007 * function described (one day) else where.
3008 *
3009 * The caller of generic_make_request must make sure that bi_io_vec
3010 * are set to describe the memory buffer, and that bi_dev and bi_sector are
3011 * set to describe the device address, and the
3012 * bi_end_io and optionally bi_private are set to describe how
3013 * completion notification should be signaled.
3014 *
3015 * generic_make_request and the drivers it calls may use bi_next if this
3016 * bio happens to be merged with someone else, and may change bi_dev and
3017 * bi_sector for remaps as it sees fit. So the values of these fields
3018 * should NOT be depended on after the call to generic_make_request.
3019 */
3020void generic_make_request(struct bio *bio)
3021{
3022 request_queue_t *q;
3023 sector_t maxsector;
3024 int ret, nr_sectors = bio_sectors(bio);
Jens Axboe2056a782006-03-23 20:00:26 +01003025 dev_t old_dev;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003026
3027 might_sleep();
3028 /* Test device or partition size, when known. */
3029 maxsector = bio->bi_bdev->bd_inode->i_size >> 9;
3030 if (maxsector) {
3031 sector_t sector = bio->bi_sector;
3032
3033 if (maxsector < nr_sectors || maxsector - nr_sectors < sector) {
3034 /*
3035 * This may well happen - the kernel calls bread()
3036 * without checking the size of the device, e.g., when
3037 * mounting a device.
3038 */
3039 handle_bad_sector(bio);
3040 goto end_io;
3041 }
3042 }
3043
3044 /*
3045 * Resolve the mapping until finished. (drivers are
3046 * still free to implement/resolve their own stacking
3047 * by explicitly returning 0)
3048 *
3049 * NOTE: we don't repeat the blk_size check for each new device.
3050 * Stacking drivers are expected to know what they are doing.
3051 */
Jens Axboe2056a782006-03-23 20:00:26 +01003052 maxsector = -1;
3053 old_dev = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003054 do {
3055 char b[BDEVNAME_SIZE];
3056
3057 q = bdev_get_queue(bio->bi_bdev);
3058 if (!q) {
3059 printk(KERN_ERR
3060 "generic_make_request: Trying to access "
3061 "nonexistent block-device %s (%Lu)\n",
3062 bdevname(bio->bi_bdev, b),
3063 (long long) bio->bi_sector);
3064end_io:
3065 bio_endio(bio, bio->bi_size, -EIO);
3066 break;
3067 }
3068
3069 if (unlikely(bio_sectors(bio) > q->max_hw_sectors)) {
3070 printk("bio too big device %s (%u > %u)\n",
3071 bdevname(bio->bi_bdev, b),
3072 bio_sectors(bio),
3073 q->max_hw_sectors);
3074 goto end_io;
3075 }
3076
Nick Pigginfde6ad22005-06-23 00:08:53 -07003077 if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003078 goto end_io;
3079
Linus Torvalds1da177e2005-04-16 15:20:36 -07003080 /*
3081 * If this device has partitions, remap block n
3082 * of partition p to block n+start(p) of the disk.
3083 */
3084 blk_partition_remap(bio);
3085
Jens Axboe2056a782006-03-23 20:00:26 +01003086 if (maxsector != -1)
3087 blk_add_trace_remap(q, bio, old_dev, bio->bi_sector,
3088 maxsector);
3089
3090 blk_add_trace_bio(q, bio, BLK_TA_QUEUE);
3091
3092 maxsector = bio->bi_sector;
3093 old_dev = bio->bi_bdev->bd_dev;
3094
Linus Torvalds1da177e2005-04-16 15:20:36 -07003095 ret = q->make_request_fn(q, bio);
3096 } while (ret);
3097}
3098
3099EXPORT_SYMBOL(generic_make_request);
3100
3101/**
3102 * submit_bio: submit a bio to the block device layer for I/O
3103 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
3104 * @bio: The &struct bio which describes the I/O
3105 *
3106 * submit_bio() is very similar in purpose to generic_make_request(), and
3107 * uses that function to do most of the work. Both are fairly rough
3108 * interfaces, @bio must be presetup and ready for I/O.
3109 *
3110 */
3111void submit_bio(int rw, struct bio *bio)
3112{
3113 int count = bio_sectors(bio);
3114
3115 BIO_BUG_ON(!bio->bi_size);
3116 BIO_BUG_ON(!bio->bi_io_vec);
Jens Axboe22e2c502005-06-27 10:55:12 +02003117 bio->bi_rw |= rw;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003118 if (rw & WRITE)
Christoph Lameterf8891e52006-06-30 01:55:45 -07003119 count_vm_events(PGPGOUT, count);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003120 else
Christoph Lameterf8891e52006-06-30 01:55:45 -07003121 count_vm_events(PGPGIN, count);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003122
3123 if (unlikely(block_dump)) {
3124 char b[BDEVNAME_SIZE];
3125 printk(KERN_DEBUG "%s(%d): %s block %Lu on %s\n",
3126 current->comm, current->pid,
3127 (rw & WRITE) ? "WRITE" : "READ",
3128 (unsigned long long)bio->bi_sector,
3129 bdevname(bio->bi_bdev,b));
3130 }
3131
3132 generic_make_request(bio);
3133}
3134
3135EXPORT_SYMBOL(submit_bio);
3136
Adrian Bunk93d17d32005-06-25 14:59:10 -07003137static void blk_recalc_rq_segments(struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003138{
3139 struct bio *bio, *prevbio = NULL;
3140 int nr_phys_segs, nr_hw_segs;
3141 unsigned int phys_size, hw_size;
3142 request_queue_t *q = rq->q;
3143
3144 if (!rq->bio)
3145 return;
3146
3147 phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0;
3148 rq_for_each_bio(bio, rq) {
3149 /* Force bio hw/phys segs to be recalculated. */
3150 bio->bi_flags &= ~(1 << BIO_SEG_VALID);
3151
3152 nr_phys_segs += bio_phys_segments(q, bio);
3153 nr_hw_segs += bio_hw_segments(q, bio);
3154 if (prevbio) {
3155 int pseg = phys_size + prevbio->bi_size + bio->bi_size;
3156 int hseg = hw_size + prevbio->bi_size + bio->bi_size;
3157
3158 if (blk_phys_contig_segment(q, prevbio, bio) &&
3159 pseg <= q->max_segment_size) {
3160 nr_phys_segs--;
3161 phys_size += prevbio->bi_size + bio->bi_size;
3162 } else
3163 phys_size = 0;
3164
3165 if (blk_hw_contig_segment(q, prevbio, bio) &&
3166 hseg <= q->max_segment_size) {
3167 nr_hw_segs--;
3168 hw_size += prevbio->bi_size + bio->bi_size;
3169 } else
3170 hw_size = 0;
3171 }
3172 prevbio = bio;
3173 }
3174
3175 rq->nr_phys_segments = nr_phys_segs;
3176 rq->nr_hw_segments = nr_hw_segs;
3177}
3178
Adrian Bunk93d17d32005-06-25 14:59:10 -07003179static void blk_recalc_rq_sectors(struct request *rq, int nsect)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003180{
3181 if (blk_fs_request(rq)) {
3182 rq->hard_sector += nsect;
3183 rq->hard_nr_sectors -= nsect;
3184
3185 /*
3186 * Move the I/O submission pointers ahead if required.
3187 */
3188 if ((rq->nr_sectors >= rq->hard_nr_sectors) &&
3189 (rq->sector <= rq->hard_sector)) {
3190 rq->sector = rq->hard_sector;
3191 rq->nr_sectors = rq->hard_nr_sectors;
3192 rq->hard_cur_sectors = bio_cur_sectors(rq->bio);
3193 rq->current_nr_sectors = rq->hard_cur_sectors;
3194 rq->buffer = bio_data(rq->bio);
3195 }
3196
3197 /*
3198 * if total number of sectors is less than the first segment
3199 * size, something has gone terribly wrong
3200 */
3201 if (rq->nr_sectors < rq->current_nr_sectors) {
3202 printk("blk: request botched\n");
3203 rq->nr_sectors = rq->current_nr_sectors;
3204 }
3205 }
3206}
3207
3208static int __end_that_request_first(struct request *req, int uptodate,
3209 int nr_bytes)
3210{
3211 int total_bytes, bio_nbytes, error, next_idx = 0;
3212 struct bio *bio;
3213
Jens Axboe2056a782006-03-23 20:00:26 +01003214 blk_add_trace_rq(req->q, req, BLK_TA_COMPLETE);
3215
Linus Torvalds1da177e2005-04-16 15:20:36 -07003216 /*
3217 * extend uptodate bool to allow < 0 value to be direct io error
3218 */
3219 error = 0;
3220 if (end_io_error(uptodate))
3221 error = !uptodate ? -EIO : uptodate;
3222
3223 /*
3224 * for a REQ_BLOCK_PC request, we want to carry any eventual
3225 * sense key with us all the way through
3226 */
3227 if (!blk_pc_request(req))
3228 req->errors = 0;
3229
3230 if (!uptodate) {
3231 if (blk_fs_request(req) && !(req->flags & REQ_QUIET))
3232 printk("end_request: I/O error, dev %s, sector %llu\n",
3233 req->rq_disk ? req->rq_disk->disk_name : "?",
3234 (unsigned long long)req->sector);
3235 }
3236
Jens Axboed72d9042005-11-01 08:35:42 +01003237 if (blk_fs_request(req) && req->rq_disk) {
Jens Axboea3623572005-11-01 09:26:16 +01003238 const int rw = rq_data_dir(req);
3239
Jens Axboe53e86062006-01-17 11:09:27 +01003240 disk_stat_add(req->rq_disk, sectors[rw], nr_bytes >> 9);
Jens Axboed72d9042005-11-01 08:35:42 +01003241 }
3242
Linus Torvalds1da177e2005-04-16 15:20:36 -07003243 total_bytes = bio_nbytes = 0;
3244 while ((bio = req->bio) != NULL) {
3245 int nbytes;
3246
3247 if (nr_bytes >= bio->bi_size) {
3248 req->bio = bio->bi_next;
3249 nbytes = bio->bi_size;
Tejun Heo797e7db2006-01-06 09:51:03 +01003250 if (!ordered_bio_endio(req, bio, nbytes, error))
3251 bio_endio(bio, nbytes, error);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003252 next_idx = 0;
3253 bio_nbytes = 0;
3254 } else {
3255 int idx = bio->bi_idx + next_idx;
3256
3257 if (unlikely(bio->bi_idx >= bio->bi_vcnt)) {
3258 blk_dump_rq_flags(req, "__end_that");
3259 printk("%s: bio idx %d >= vcnt %d\n",
3260 __FUNCTION__,
3261 bio->bi_idx, bio->bi_vcnt);
3262 break;
3263 }
3264
3265 nbytes = bio_iovec_idx(bio, idx)->bv_len;
3266 BIO_BUG_ON(nbytes > bio->bi_size);
3267
3268 /*
3269 * not a complete bvec done
3270 */
3271 if (unlikely(nbytes > nr_bytes)) {
3272 bio_nbytes += nr_bytes;
3273 total_bytes += nr_bytes;
3274 break;
3275 }
3276
3277 /*
3278 * advance to the next vector
3279 */
3280 next_idx++;
3281 bio_nbytes += nbytes;
3282 }
3283
3284 total_bytes += nbytes;
3285 nr_bytes -= nbytes;
3286
3287 if ((bio = req->bio)) {
3288 /*
3289 * end more in this run, or just return 'not-done'
3290 */
3291 if (unlikely(nr_bytes <= 0))
3292 break;
3293 }
3294 }
3295
3296 /*
3297 * completely done
3298 */
3299 if (!req->bio)
3300 return 0;
3301
3302 /*
3303 * if the request wasn't completed, update state
3304 */
3305 if (bio_nbytes) {
Tejun Heo797e7db2006-01-06 09:51:03 +01003306 if (!ordered_bio_endio(req, bio, bio_nbytes, error))
3307 bio_endio(bio, bio_nbytes, error);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003308 bio->bi_idx += next_idx;
3309 bio_iovec(bio)->bv_offset += nr_bytes;
3310 bio_iovec(bio)->bv_len -= nr_bytes;
3311 }
3312
3313 blk_recalc_rq_sectors(req, total_bytes >> 9);
3314 blk_recalc_rq_segments(req);
3315 return 1;
3316}
3317
3318/**
3319 * end_that_request_first - end I/O on a request
3320 * @req: the request being processed
3321 * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error
3322 * @nr_sectors: number of sectors to end I/O on
3323 *
3324 * Description:
3325 * Ends I/O on a number of sectors attached to @req, and sets it up
3326 * for the next range of segments (if any) in the cluster.
3327 *
3328 * Return:
3329 * 0 - we are done with this request, call end_that_request_last()
3330 * 1 - still buffers pending for this request
3331 **/
3332int end_that_request_first(struct request *req, int uptodate, int nr_sectors)
3333{
3334 return __end_that_request_first(req, uptodate, nr_sectors << 9);
3335}
3336
3337EXPORT_SYMBOL(end_that_request_first);
3338
3339/**
3340 * end_that_request_chunk - end I/O on a request
3341 * @req: the request being processed
3342 * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error
3343 * @nr_bytes: number of bytes to complete
3344 *
3345 * Description:
3346 * Ends I/O on a number of bytes attached to @req, and sets it up
3347 * for the next range of segments (if any). Like end_that_request_first(),
3348 * but deals with bytes instead of sectors.
3349 *
3350 * Return:
3351 * 0 - we are done with this request, call end_that_request_last()
3352 * 1 - still buffers pending for this request
3353 **/
3354int end_that_request_chunk(struct request *req, int uptodate, int nr_bytes)
3355{
3356 return __end_that_request_first(req, uptodate, nr_bytes);
3357}
3358
3359EXPORT_SYMBOL(end_that_request_chunk);
3360
3361/*
Jens Axboeff856ba2006-01-09 16:02:34 +01003362 * splice the completion data to a local structure and hand off to
3363 * process_completion_queue() to complete the requests
3364 */
3365static void blk_done_softirq(struct softirq_action *h)
3366{
Oleg Nesterov626ab0e2006-06-23 02:05:55 -07003367 struct list_head *cpu_list, local_list;
Jens Axboeff856ba2006-01-09 16:02:34 +01003368
3369 local_irq_disable();
3370 cpu_list = &__get_cpu_var(blk_cpu_done);
Oleg Nesterov626ab0e2006-06-23 02:05:55 -07003371 list_replace_init(cpu_list, &local_list);
Jens Axboeff856ba2006-01-09 16:02:34 +01003372 local_irq_enable();
3373
3374 while (!list_empty(&local_list)) {
3375 struct request *rq = list_entry(local_list.next, struct request, donelist);
3376
3377 list_del_init(&rq->donelist);
3378 rq->q->softirq_done_fn(rq);
3379 }
3380}
3381
3382#ifdef CONFIG_HOTPLUG_CPU
3383
3384static int blk_cpu_notify(struct notifier_block *self, unsigned long action,
3385 void *hcpu)
3386{
3387 /*
3388 * If a CPU goes away, splice its entries to the current CPU
3389 * and trigger a run of the softirq
3390 */
3391 if (action == CPU_DEAD) {
3392 int cpu = (unsigned long) hcpu;
3393
3394 local_irq_disable();
3395 list_splice_init(&per_cpu(blk_cpu_done, cpu),
3396 &__get_cpu_var(blk_cpu_done));
3397 raise_softirq_irqoff(BLOCK_SOFTIRQ);
3398 local_irq_enable();
3399 }
3400
3401 return NOTIFY_OK;
3402}
3403
3404
Chandra Seetharaman054cc8a2006-06-27 02:54:07 -07003405static struct notifier_block __devinitdata blk_cpu_notifier = {
Jens Axboeff856ba2006-01-09 16:02:34 +01003406 .notifier_call = blk_cpu_notify,
3407};
3408
3409#endif /* CONFIG_HOTPLUG_CPU */
3410
3411/**
3412 * blk_complete_request - end I/O on a request
3413 * @req: the request being processed
3414 *
3415 * Description:
3416 * Ends all I/O on a request. It does not handle partial completions,
Andreas Mohrd6e05ed2006-06-26 18:35:02 +02003417 * unless the driver actually implements this in its completion callback
Jens Axboeff856ba2006-01-09 16:02:34 +01003418 * through requeueing. Theh actual completion happens out-of-order,
3419 * through a softirq handler. The user must have registered a completion
3420 * callback through blk_queue_softirq_done().
3421 **/
3422
3423void blk_complete_request(struct request *req)
3424{
3425 struct list_head *cpu_list;
3426 unsigned long flags;
3427
3428 BUG_ON(!req->q->softirq_done_fn);
3429
3430 local_irq_save(flags);
3431
3432 cpu_list = &__get_cpu_var(blk_cpu_done);
3433 list_add_tail(&req->donelist, cpu_list);
3434 raise_softirq_irqoff(BLOCK_SOFTIRQ);
3435
3436 local_irq_restore(flags);
3437}
3438
3439EXPORT_SYMBOL(blk_complete_request);
3440
3441/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07003442 * queue lock must be held
3443 */
Tejun Heo8ffdc652006-01-06 09:49:03 +01003444void end_that_request_last(struct request *req, int uptodate)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003445{
3446 struct gendisk *disk = req->rq_disk;
Tejun Heo8ffdc652006-01-06 09:49:03 +01003447 int error;
3448
3449 /*
3450 * extend uptodate bool to allow < 0 value to be direct io error
3451 */
3452 error = 0;
3453 if (end_io_error(uptodate))
3454 error = !uptodate ? -EIO : uptodate;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003455
3456 if (unlikely(laptop_mode) && blk_fs_request(req))
3457 laptop_io_completion();
3458
Jens Axboefd0ff8a2006-05-23 11:23:49 +02003459 /*
3460 * Account IO completion. bar_rq isn't accounted as a normal
3461 * IO on queueing nor completion. Accounting the containing
3462 * request is enough.
3463 */
3464 if (disk && blk_fs_request(req) && req != &req->q->bar_rq) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003465 unsigned long duration = jiffies - req->start_time;
Jens Axboea3623572005-11-01 09:26:16 +01003466 const int rw = rq_data_dir(req);
3467
3468 __disk_stat_inc(disk, ios[rw]);
3469 __disk_stat_add(disk, ticks[rw], duration);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003470 disk_round_stats(disk);
3471 disk->in_flight--;
3472 }
3473 if (req->end_io)
Tejun Heo8ffdc652006-01-06 09:49:03 +01003474 req->end_io(req, error);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003475 else
3476 __blk_put_request(req->q, req);
3477}
3478
3479EXPORT_SYMBOL(end_that_request_last);
3480
3481void end_request(struct request *req, int uptodate)
3482{
3483 if (!end_that_request_first(req, uptodate, req->hard_cur_sectors)) {
3484 add_disk_randomness(req->rq_disk);
3485 blkdev_dequeue_request(req);
Tejun Heo8ffdc652006-01-06 09:49:03 +01003486 end_that_request_last(req, uptodate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003487 }
3488}
3489
3490EXPORT_SYMBOL(end_request);
3491
3492void blk_rq_bio_prep(request_queue_t *q, struct request *rq, struct bio *bio)
3493{
Jens Axboe1959d212006-07-06 10:18:05 +02003494 /* first two bits are identical in rq->flags and bio->bi_rw */
3495 rq->flags |= (bio->bi_rw & 3);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003496
3497 rq->nr_phys_segments = bio_phys_segments(q, bio);
3498 rq->nr_hw_segments = bio_hw_segments(q, bio);
3499 rq->current_nr_sectors = bio_cur_sectors(bio);
3500 rq->hard_cur_sectors = rq->current_nr_sectors;
3501 rq->hard_nr_sectors = rq->nr_sectors = bio_sectors(bio);
3502 rq->buffer = bio_data(bio);
3503
3504 rq->bio = rq->biotail = bio;
3505}
3506
3507EXPORT_SYMBOL(blk_rq_bio_prep);
3508
3509int kblockd_schedule_work(struct work_struct *work)
3510{
3511 return queue_work(kblockd_workqueue, work);
3512}
3513
3514EXPORT_SYMBOL(kblockd_schedule_work);
3515
3516void kblockd_flush(void)
3517{
3518 flush_workqueue(kblockd_workqueue);
3519}
3520EXPORT_SYMBOL(kblockd_flush);
3521
3522int __init blk_dev_init(void)
3523{
Jens Axboeff856ba2006-01-09 16:02:34 +01003524 int i;
3525
Linus Torvalds1da177e2005-04-16 15:20:36 -07003526 kblockd_workqueue = create_workqueue("kblockd");
3527 if (!kblockd_workqueue)
3528 panic("Failed to create kblockd\n");
3529
3530 request_cachep = kmem_cache_create("blkdev_requests",
3531 sizeof(struct request), 0, SLAB_PANIC, NULL, NULL);
3532
3533 requestq_cachep = kmem_cache_create("blkdev_queue",
3534 sizeof(request_queue_t), 0, SLAB_PANIC, NULL, NULL);
3535
3536 iocontext_cachep = kmem_cache_create("blkdev_ioc",
3537 sizeof(struct io_context), 0, SLAB_PANIC, NULL, NULL);
3538
KAMEZAWA Hiroyuki0a945022006-03-28 01:56:37 -08003539 for_each_possible_cpu(i)
Jens Axboeff856ba2006-01-09 16:02:34 +01003540 INIT_LIST_HEAD(&per_cpu(blk_cpu_done, i));
3541
3542 open_softirq(BLOCK_SOFTIRQ, blk_done_softirq, NULL);
Chandra Seetharaman5a67e4c2006-06-27 02:54:11 -07003543 register_hotcpu_notifier(&blk_cpu_notifier);
Jens Axboeff856ba2006-01-09 16:02:34 +01003544
Linus Torvalds1da177e2005-04-16 15:20:36 -07003545 blk_max_low_pfn = max_low_pfn;
3546 blk_max_pfn = max_pfn;
3547
3548 return 0;
3549}
3550
3551/*
3552 * IO Context helper functions
3553 */
3554void put_io_context(struct io_context *ioc)
3555{
3556 if (ioc == NULL)
3557 return;
3558
3559 BUG_ON(atomic_read(&ioc->refcount) == 0);
3560
3561 if (atomic_dec_and_test(&ioc->refcount)) {
Jens Axboee2d74ac2006-03-28 08:59:01 +02003562 struct cfq_io_context *cic;
3563
Al Viro334e94d2006-03-18 15:05:53 -05003564 rcu_read_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003565 if (ioc->aic && ioc->aic->dtor)
3566 ioc->aic->dtor(ioc->aic);
Jens Axboee2d74ac2006-03-28 08:59:01 +02003567 if (ioc->cic_root.rb_node != NULL) {
Jens Axboe7143dd42006-03-28 09:00:28 +02003568 struct rb_node *n = rb_first(&ioc->cic_root);
3569
3570 cic = rb_entry(n, struct cfq_io_context, rb_node);
Jens Axboee2d74ac2006-03-28 08:59:01 +02003571 cic->dtor(ioc);
3572 }
Al Viro334e94d2006-03-18 15:05:53 -05003573 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003574
3575 kmem_cache_free(iocontext_cachep, ioc);
3576 }
3577}
3578EXPORT_SYMBOL(put_io_context);
3579
3580/* Called by the exitting task */
3581void exit_io_context(void)
3582{
3583 unsigned long flags;
3584 struct io_context *ioc;
Jens Axboee2d74ac2006-03-28 08:59:01 +02003585 struct cfq_io_context *cic;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003586
3587 local_irq_save(flags);
Jens Axboe22e2c502005-06-27 10:55:12 +02003588 task_lock(current);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003589 ioc = current->io_context;
3590 current->io_context = NULL;
Jens Axboe22e2c502005-06-27 10:55:12 +02003591 ioc->task = NULL;
3592 task_unlock(current);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003593 local_irq_restore(flags);
3594
3595 if (ioc->aic && ioc->aic->exit)
3596 ioc->aic->exit(ioc->aic);
Jens Axboee2d74ac2006-03-28 08:59:01 +02003597 if (ioc->cic_root.rb_node != NULL) {
3598 cic = rb_entry(rb_first(&ioc->cic_root), struct cfq_io_context, rb_node);
3599 cic->exit(ioc);
3600 }
3601
Linus Torvalds1da177e2005-04-16 15:20:36 -07003602 put_io_context(ioc);
3603}
3604
3605/*
3606 * If the current task has no IO context then create one and initialise it.
Nick Pigginfb3cc432005-06-28 20:45:15 -07003607 * Otherwise, return its existing IO context.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003608 *
Nick Pigginfb3cc432005-06-28 20:45:15 -07003609 * This returned IO context doesn't have a specifically elevated refcount,
3610 * but since the current task itself holds a reference, the context can be
3611 * used in general code, so long as it stays within `current` context.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003612 */
Al Viro8267e262005-10-21 03:20:53 -04003613struct io_context *current_io_context(gfp_t gfp_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003614{
3615 struct task_struct *tsk = current;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003616 struct io_context *ret;
3617
Linus Torvalds1da177e2005-04-16 15:20:36 -07003618 ret = tsk->io_context;
Nick Pigginfb3cc432005-06-28 20:45:15 -07003619 if (likely(ret))
3620 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003621
3622 ret = kmem_cache_alloc(iocontext_cachep, gfp_flags);
3623 if (ret) {
3624 atomic_set(&ret->refcount, 1);
Jens Axboe22e2c502005-06-27 10:55:12 +02003625 ret->task = current;
3626 ret->set_ioprio = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003627 ret->last_waited = jiffies; /* doesn't matter... */
3628 ret->nr_batch_requests = 0; /* because this is 0 */
3629 ret->aic = NULL;
Jens Axboee2d74ac2006-03-28 08:59:01 +02003630 ret->cic_root.rb_node = NULL;
Nick Pigginfb3cc432005-06-28 20:45:15 -07003631 tsk->io_context = ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003632 }
3633
3634 return ret;
3635}
Nick Pigginfb3cc432005-06-28 20:45:15 -07003636EXPORT_SYMBOL(current_io_context);
3637
3638/*
3639 * If the current task has no IO context then create one and initialise it.
3640 * If it does have a context, take a ref on it.
3641 *
3642 * This is always called in the context of the task which submitted the I/O.
3643 */
Al Viro8267e262005-10-21 03:20:53 -04003644struct io_context *get_io_context(gfp_t gfp_flags)
Nick Pigginfb3cc432005-06-28 20:45:15 -07003645{
3646 struct io_context *ret;
3647 ret = current_io_context(gfp_flags);
3648 if (likely(ret))
3649 atomic_inc(&ret->refcount);
3650 return ret;
3651}
Linus Torvalds1da177e2005-04-16 15:20:36 -07003652EXPORT_SYMBOL(get_io_context);
3653
3654void copy_io_context(struct io_context **pdst, struct io_context **psrc)
3655{
3656 struct io_context *src = *psrc;
3657 struct io_context *dst = *pdst;
3658
3659 if (src) {
3660 BUG_ON(atomic_read(&src->refcount) == 0);
3661 atomic_inc(&src->refcount);
3662 put_io_context(dst);
3663 *pdst = src;
3664 }
3665}
3666EXPORT_SYMBOL(copy_io_context);
3667
3668void swap_io_context(struct io_context **ioc1, struct io_context **ioc2)
3669{
3670 struct io_context *temp;
3671 temp = *ioc1;
3672 *ioc1 = *ioc2;
3673 *ioc2 = temp;
3674}
3675EXPORT_SYMBOL(swap_io_context);
3676
3677/*
3678 * sysfs parts below
3679 */
3680struct queue_sysfs_entry {
3681 struct attribute attr;
3682 ssize_t (*show)(struct request_queue *, char *);
3683 ssize_t (*store)(struct request_queue *, const char *, size_t);
3684};
3685
3686static ssize_t
3687queue_var_show(unsigned int var, char *page)
3688{
3689 return sprintf(page, "%d\n", var);
3690}
3691
3692static ssize_t
3693queue_var_store(unsigned long *var, const char *page, size_t count)
3694{
3695 char *p = (char *) page;
3696
3697 *var = simple_strtoul(p, &p, 10);
3698 return count;
3699}
3700
3701static ssize_t queue_requests_show(struct request_queue *q, char *page)
3702{
3703 return queue_var_show(q->nr_requests, (page));
3704}
3705
3706static ssize_t
3707queue_requests_store(struct request_queue *q, const char *page, size_t count)
3708{
3709 struct request_list *rl = &q->rq;
Al Viroc981ff92006-03-18 13:51:29 -05003710 unsigned long nr;
3711 int ret = queue_var_store(&nr, page, count);
3712 if (nr < BLKDEV_MIN_RQ)
3713 nr = BLKDEV_MIN_RQ;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003714
Al Viroc981ff92006-03-18 13:51:29 -05003715 spin_lock_irq(q->queue_lock);
3716 q->nr_requests = nr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003717 blk_queue_congestion_threshold(q);
3718
3719 if (rl->count[READ] >= queue_congestion_on_threshold(q))
3720 set_queue_congested(q, READ);
3721 else if (rl->count[READ] < queue_congestion_off_threshold(q))
3722 clear_queue_congested(q, READ);
3723
3724 if (rl->count[WRITE] >= queue_congestion_on_threshold(q))
3725 set_queue_congested(q, WRITE);
3726 else if (rl->count[WRITE] < queue_congestion_off_threshold(q))
3727 clear_queue_congested(q, WRITE);
3728
3729 if (rl->count[READ] >= q->nr_requests) {
3730 blk_set_queue_full(q, READ);
3731 } else if (rl->count[READ]+1 <= q->nr_requests) {
3732 blk_clear_queue_full(q, READ);
3733 wake_up(&rl->wait[READ]);
3734 }
3735
3736 if (rl->count[WRITE] >= q->nr_requests) {
3737 blk_set_queue_full(q, WRITE);
3738 } else if (rl->count[WRITE]+1 <= q->nr_requests) {
3739 blk_clear_queue_full(q, WRITE);
3740 wake_up(&rl->wait[WRITE]);
3741 }
Al Viroc981ff92006-03-18 13:51:29 -05003742 spin_unlock_irq(q->queue_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003743 return ret;
3744}
3745
3746static ssize_t queue_ra_show(struct request_queue *q, char *page)
3747{
3748 int ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10);
3749
3750 return queue_var_show(ra_kb, (page));
3751}
3752
3753static ssize_t
3754queue_ra_store(struct request_queue *q, const char *page, size_t count)
3755{
3756 unsigned long ra_kb;
3757 ssize_t ret = queue_var_store(&ra_kb, page, count);
3758
3759 spin_lock_irq(q->queue_lock);
3760 if (ra_kb > (q->max_sectors >> 1))
3761 ra_kb = (q->max_sectors >> 1);
3762
3763 q->backing_dev_info.ra_pages = ra_kb >> (PAGE_CACHE_SHIFT - 10);
3764 spin_unlock_irq(q->queue_lock);
3765
3766 return ret;
3767}
3768
3769static ssize_t queue_max_sectors_show(struct request_queue *q, char *page)
3770{
3771 int max_sectors_kb = q->max_sectors >> 1;
3772
3773 return queue_var_show(max_sectors_kb, (page));
3774}
3775
3776static ssize_t
3777queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
3778{
3779 unsigned long max_sectors_kb,
3780 max_hw_sectors_kb = q->max_hw_sectors >> 1,
3781 page_kb = 1 << (PAGE_CACHE_SHIFT - 10);
3782 ssize_t ret = queue_var_store(&max_sectors_kb, page, count);
3783 int ra_kb;
3784
3785 if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
3786 return -EINVAL;
3787 /*
3788 * Take the queue lock to update the readahead and max_sectors
3789 * values synchronously:
3790 */
3791 spin_lock_irq(q->queue_lock);
3792 /*
3793 * Trim readahead window as well, if necessary:
3794 */
3795 ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10);
3796 if (ra_kb > max_sectors_kb)
3797 q->backing_dev_info.ra_pages =
3798 max_sectors_kb >> (PAGE_CACHE_SHIFT - 10);
3799
3800 q->max_sectors = max_sectors_kb << 1;
3801 spin_unlock_irq(q->queue_lock);
3802
3803 return ret;
3804}
3805
3806static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page)
3807{
3808 int max_hw_sectors_kb = q->max_hw_sectors >> 1;
3809
3810 return queue_var_show(max_hw_sectors_kb, (page));
3811}
3812
3813
3814static struct queue_sysfs_entry queue_requests_entry = {
3815 .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
3816 .show = queue_requests_show,
3817 .store = queue_requests_store,
3818};
3819
3820static struct queue_sysfs_entry queue_ra_entry = {
3821 .attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR },
3822 .show = queue_ra_show,
3823 .store = queue_ra_store,
3824};
3825
3826static struct queue_sysfs_entry queue_max_sectors_entry = {
3827 .attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR },
3828 .show = queue_max_sectors_show,
3829 .store = queue_max_sectors_store,
3830};
3831
3832static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
3833 .attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO },
3834 .show = queue_max_hw_sectors_show,
3835};
3836
3837static struct queue_sysfs_entry queue_iosched_entry = {
3838 .attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR },
3839 .show = elv_iosched_show,
3840 .store = elv_iosched_store,
3841};
3842
3843static struct attribute *default_attrs[] = {
3844 &queue_requests_entry.attr,
3845 &queue_ra_entry.attr,
3846 &queue_max_hw_sectors_entry.attr,
3847 &queue_max_sectors_entry.attr,
3848 &queue_iosched_entry.attr,
3849 NULL,
3850};
3851
3852#define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
3853
3854static ssize_t
3855queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
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);
3859 ssize_t res;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003860
Linus Torvalds1da177e2005-04-16 15:20:36 -07003861 if (!entry->show)
Dmitry Torokhov6c1852a2005-04-29 01:26:06 -05003862 return -EIO;
Al Viro483f4af2006-03-18 18:34:37 -05003863 mutex_lock(&q->sysfs_lock);
3864 if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
3865 mutex_unlock(&q->sysfs_lock);
3866 return -ENOENT;
3867 }
3868 res = entry->show(q, page);
3869 mutex_unlock(&q->sysfs_lock);
3870 return res;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003871}
3872
3873static ssize_t
3874queue_attr_store(struct kobject *kobj, struct attribute *attr,
3875 const char *page, size_t length)
3876{
3877 struct queue_sysfs_entry *entry = to_queue(attr);
Al Viro483f4af2006-03-18 18:34:37 -05003878 request_queue_t *q = container_of(kobj, struct request_queue, kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003879
Al Viro483f4af2006-03-18 18:34:37 -05003880 ssize_t res;
3881
Linus Torvalds1da177e2005-04-16 15:20:36 -07003882 if (!entry->store)
Dmitry Torokhov6c1852a2005-04-29 01:26:06 -05003883 return -EIO;
Al Viro483f4af2006-03-18 18:34:37 -05003884 mutex_lock(&q->sysfs_lock);
3885 if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
3886 mutex_unlock(&q->sysfs_lock);
3887 return -ENOENT;
3888 }
3889 res = entry->store(q, page, length);
3890 mutex_unlock(&q->sysfs_lock);
3891 return res;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003892}
3893
3894static struct sysfs_ops queue_sysfs_ops = {
3895 .show = queue_attr_show,
3896 .store = queue_attr_store,
3897};
3898
Adrian Bunk93d17d32005-06-25 14:59:10 -07003899static struct kobj_type queue_ktype = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003900 .sysfs_ops = &queue_sysfs_ops,
3901 .default_attrs = default_attrs,
Al Viro483f4af2006-03-18 18:34:37 -05003902 .release = blk_release_queue,
Linus Torvalds1da177e2005-04-16 15:20:36 -07003903};
3904
3905int blk_register_queue(struct gendisk *disk)
3906{
3907 int ret;
3908
3909 request_queue_t *q = disk->queue;
3910
3911 if (!q || !q->request_fn)
3912 return -ENXIO;
3913
3914 q->kobj.parent = kobject_get(&disk->kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003915
Al Viro483f4af2006-03-18 18:34:37 -05003916 ret = kobject_add(&q->kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003917 if (ret < 0)
3918 return ret;
3919
Al Viro483f4af2006-03-18 18:34:37 -05003920 kobject_uevent(&q->kobj, KOBJ_ADD);
3921
Linus Torvalds1da177e2005-04-16 15:20:36 -07003922 ret = elv_register_queue(q);
3923 if (ret) {
Al Viro483f4af2006-03-18 18:34:37 -05003924 kobject_uevent(&q->kobj, KOBJ_REMOVE);
3925 kobject_del(&q->kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003926 return ret;
3927 }
3928
3929 return 0;
3930}
3931
3932void blk_unregister_queue(struct gendisk *disk)
3933{
3934 request_queue_t *q = disk->queue;
3935
3936 if (q && q->request_fn) {
3937 elv_unregister_queue(q);
3938
Al Viro483f4af2006-03-18 18:34:37 -05003939 kobject_uevent(&q->kobj, KOBJ_REMOVE);
3940 kobject_del(&q->kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003941 kobject_put(&disk->kobj);
3942 }
3943}