blob: 38c293b987b77212bec48450dd1529d71a3f582f [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>
Andrew Mortonfaccbd4b2006-12-10 02:19:35 -080028#include <linux/task_io_accounting_ops.h>
Jens Axboeff856ba2006-01-09 16:02:34 +010029#include <linux/interrupt.h>
30#include <linux/cpu.h>
Jens Axboe2056a782006-03-23 20:00:26 +010031#include <linux/blktrace_api.h>
Akinobu Mitac17bb492006-12-08 02:39:46 -080032#include <linux/fault-inject.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070033
34/*
35 * for max sense size
36 */
37#include <scsi/scsi_cmnd.h>
38
David Howells65f27f32006-11-22 14:55:48 +000039static void blk_unplug_work(struct work_struct *work);
Linus Torvalds1da177e2005-04-16 15:20:36 -070040static void blk_unplug_timeout(unsigned long data);
Adrian Bunk93d17d32005-06-25 14:59:10 -070041static void drive_stat_acct(struct request *rq, int nr_sectors, int new_io);
Tejun Heo52d9e672006-01-06 09:49:58 +010042static void init_request_from_bio(struct request *req, struct bio *bio);
43static int __make_request(request_queue_t *q, struct bio *bio);
Jens Axboeb5deef92006-07-19 23:39:40 +020044static struct io_context *current_io_context(gfp_t gfp_flags, int node);
Linus Torvalds1da177e2005-04-16 15:20:36 -070045
46/*
47 * For the allocated request tables
48 */
Christoph Lametere18b8902006-12-06 20:33:20 -080049static struct kmem_cache *request_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -070050
51/*
52 * For queue allocation
53 */
Christoph Lametere18b8902006-12-06 20:33:20 -080054static struct kmem_cache *requestq_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -070055
56/*
57 * For io context allocations
58 */
Christoph Lametere18b8902006-12-06 20:33:20 -080059static struct kmem_cache *iocontext_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -070060
Linus Torvalds1da177e2005-04-16 15:20:36 -070061/*
62 * Controlling structure to kblockd
63 */
Jens Axboeff856ba2006-01-09 16:02:34 +010064static struct workqueue_struct *kblockd_workqueue;
Linus Torvalds1da177e2005-04-16 15:20:36 -070065
66unsigned long blk_max_low_pfn, blk_max_pfn;
67
68EXPORT_SYMBOL(blk_max_low_pfn);
69EXPORT_SYMBOL(blk_max_pfn);
70
Jens Axboeff856ba2006-01-09 16:02:34 +010071static DEFINE_PER_CPU(struct list_head, blk_cpu_done);
72
Linus Torvalds1da177e2005-04-16 15:20:36 -070073/* Amount of time in which a process may batch requests */
74#define BLK_BATCH_TIME (HZ/50UL)
75
76/* Number of requests a "batching" process may submit */
77#define BLK_BATCH_REQ 32
78
79/*
80 * Return the threshold (number of used requests) at which the queue is
81 * considered to be congested. It include a little hysteresis to keep the
82 * context switch rate down.
83 */
84static inline int queue_congestion_on_threshold(struct request_queue *q)
85{
86 return q->nr_congestion_on;
87}
88
89/*
90 * The threshold at which a queue is considered to be uncongested
91 */
92static inline int queue_congestion_off_threshold(struct request_queue *q)
93{
94 return q->nr_congestion_off;
95}
96
97static void blk_queue_congestion_threshold(struct request_queue *q)
98{
99 int nr;
100
101 nr = q->nr_requests - (q->nr_requests / 8) + 1;
102 if (nr > q->nr_requests)
103 nr = q->nr_requests;
104 q->nr_congestion_on = nr;
105
106 nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests / 16) - 1;
107 if (nr < 1)
108 nr = 1;
109 q->nr_congestion_off = nr;
110}
111
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112/**
113 * blk_get_backing_dev_info - get the address of a queue's backing_dev_info
114 * @bdev: device
115 *
116 * Locates the passed device's request queue and returns the address of its
117 * backing_dev_info
118 *
119 * Will return NULL if the request queue cannot be located.
120 */
121struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev)
122{
123 struct backing_dev_info *ret = NULL;
124 request_queue_t *q = bdev_get_queue(bdev);
125
126 if (q)
127 ret = &q->backing_dev_info;
128 return ret;
129}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130EXPORT_SYMBOL(blk_get_backing_dev_info);
131
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132/**
133 * blk_queue_prep_rq - set a prepare_request function for queue
134 * @q: queue
135 * @pfn: prepare_request function
136 *
137 * It's possible for a queue to register a prepare_request callback which
138 * is invoked before the request is handed to the request_fn. The goal of
139 * the function is to prepare a request for I/O, it can be used to build a
140 * cdb from the request data for instance.
141 *
142 */
143void blk_queue_prep_rq(request_queue_t *q, prep_rq_fn *pfn)
144{
145 q->prep_rq_fn = pfn;
146}
147
148EXPORT_SYMBOL(blk_queue_prep_rq);
149
150/**
151 * blk_queue_merge_bvec - set a merge_bvec function for queue
152 * @q: queue
153 * @mbfn: merge_bvec_fn
154 *
155 * Usually queues have static limitations on the max sectors or segments that
156 * we can put in a request. Stacking drivers may have some settings that
157 * are dynamic, and thus we have to query the queue whether it is ok to
158 * add a new bio_vec to a bio at a given offset or not. If the block device
159 * has such limitations, it needs to register a merge_bvec_fn to control
160 * the size of bio's sent to it. Note that a block device *must* allow a
161 * single page to be added to an empty bio. The block device driver may want
162 * to use the bio_split() function to deal with these bio's. By default
163 * no merge_bvec_fn is defined for a queue, and only the fixed limits are
164 * honored.
165 */
166void blk_queue_merge_bvec(request_queue_t *q, merge_bvec_fn *mbfn)
167{
168 q->merge_bvec_fn = mbfn;
169}
170
171EXPORT_SYMBOL(blk_queue_merge_bvec);
172
Jens Axboeff856ba2006-01-09 16:02:34 +0100173void blk_queue_softirq_done(request_queue_t *q, softirq_done_fn *fn)
174{
175 q->softirq_done_fn = fn;
176}
177
178EXPORT_SYMBOL(blk_queue_softirq_done);
179
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180/**
181 * blk_queue_make_request - define an alternate make_request function for a device
182 * @q: the request queue for the device to be affected
183 * @mfn: the alternate make_request function
184 *
185 * Description:
186 * The normal way for &struct bios to be passed to a device
187 * driver is for them to be collected into requests on a request
188 * queue, and then to allow the device driver to select requests
189 * off that queue when it is ready. This works well for many block
190 * devices. However some block devices (typically virtual devices
191 * such as md or lvm) do not benefit from the processing on the
192 * request queue, and are served best by having the requests passed
193 * directly to them. This can be achieved by providing a function
194 * to blk_queue_make_request().
195 *
196 * Caveat:
197 * The driver that does this *must* be able to deal appropriately
198 * with buffers in "highmemory". This can be accomplished by either calling
199 * __bio_kmap_atomic() to get a temporary kernel mapping, or by calling
200 * blk_queue_bounce() to create a buffer in normal memory.
201 **/
202void blk_queue_make_request(request_queue_t * q, make_request_fn * mfn)
203{
204 /*
205 * set defaults
206 */
207 q->nr_requests = BLKDEV_MAX_RQ;
Stuart McLaren309c0a12005-09-06 15:17:47 -0700208 blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS);
209 blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 q->make_request_fn = mfn;
211 q->backing_dev_info.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
212 q->backing_dev_info.state = 0;
213 q->backing_dev_info.capabilities = BDI_CAP_MAP_COPY;
Mike Christiedefd94b2005-12-05 02:37:06 -0600214 blk_queue_max_sectors(q, SAFE_MAX_SECTORS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215 blk_queue_hardsect_size(q, 512);
216 blk_queue_dma_alignment(q, 511);
217 blk_queue_congestion_threshold(q);
218 q->nr_batching = BLK_BATCH_REQ;
219
220 q->unplug_thresh = 4; /* hmm */
221 q->unplug_delay = (3 * HZ) / 1000; /* 3 milliseconds */
222 if (q->unplug_delay == 0)
223 q->unplug_delay = 1;
224
David Howells65f27f32006-11-22 14:55:48 +0000225 INIT_WORK(&q->unplug_work, blk_unplug_work);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700226
227 q->unplug_timer.function = blk_unplug_timeout;
228 q->unplug_timer.data = (unsigned long)q;
229
230 /*
231 * by default assume old behaviour and bounce for any highmem page
232 */
233 blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234}
235
236EXPORT_SYMBOL(blk_queue_make_request);
237
Jens Axboe1ea25ecb2006-07-18 22:24:11 +0200238static void rq_init(request_queue_t *q, struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239{
240 INIT_LIST_HEAD(&rq->queuelist);
Jens Axboeff856ba2006-01-09 16:02:34 +0100241 INIT_LIST_HEAD(&rq->donelist);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242
243 rq->errors = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244 rq->bio = rq->biotail = NULL;
Jens Axboe2e662b62006-07-13 11:55:04 +0200245 INIT_HLIST_NODE(&rq->hash);
246 RB_CLEAR_NODE(&rq->rb_node);
Jens Axboe22e2c502005-06-27 10:55:12 +0200247 rq->ioprio = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248 rq->buffer = NULL;
249 rq->ref_count = 1;
250 rq->q = q;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251 rq->special = NULL;
252 rq->data_len = 0;
253 rq->data = NULL;
Mike Christie df46b9a2005-06-20 14:04:44 +0200254 rq->nr_phys_segments = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255 rq->sense = NULL;
256 rq->end_io = NULL;
257 rq->end_io_data = NULL;
Jens Axboeff856ba2006-01-09 16:02:34 +0100258 rq->completion_data = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259}
260
261/**
262 * blk_queue_ordered - does this queue support ordered writes
Tejun Heo797e7db2006-01-06 09:51:03 +0100263 * @q: the request queue
264 * @ordered: one of QUEUE_ORDERED_*
Jens Axboefddfdea2006-01-31 15:24:34 +0100265 * @prepare_flush_fn: rq setup helper for cache flush ordered writes
Linus Torvalds1da177e2005-04-16 15:20:36 -0700266 *
267 * Description:
268 * For journalled file systems, doing ordered writes on a commit
269 * block instead of explicitly doing wait_on_buffer (which is bad
270 * for performance) can be a big win. Block drivers supporting this
271 * feature should call this function and indicate so.
272 *
273 **/
Tejun Heo797e7db2006-01-06 09:51:03 +0100274int blk_queue_ordered(request_queue_t *q, unsigned ordered,
275 prepare_flush_fn *prepare_flush_fn)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276{
Tejun Heo797e7db2006-01-06 09:51:03 +0100277 if (ordered & (QUEUE_ORDERED_PREFLUSH | QUEUE_ORDERED_POSTFLUSH) &&
278 prepare_flush_fn == NULL) {
279 printk(KERN_ERR "blk_queue_ordered: prepare_flush_fn required\n");
280 return -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281 }
Tejun Heo797e7db2006-01-06 09:51:03 +0100282
283 if (ordered != QUEUE_ORDERED_NONE &&
284 ordered != QUEUE_ORDERED_DRAIN &&
285 ordered != QUEUE_ORDERED_DRAIN_FLUSH &&
286 ordered != QUEUE_ORDERED_DRAIN_FUA &&
287 ordered != QUEUE_ORDERED_TAG &&
288 ordered != QUEUE_ORDERED_TAG_FLUSH &&
289 ordered != QUEUE_ORDERED_TAG_FUA) {
290 printk(KERN_ERR "blk_queue_ordered: bad value %d\n", ordered);
291 return -EINVAL;
292 }
293
Tetsuo Takata60481b12006-01-24 10:34:36 +0100294 q->ordered = ordered;
Tejun Heo797e7db2006-01-06 09:51:03 +0100295 q->next_ordered = ordered;
296 q->prepare_flush_fn = prepare_flush_fn;
297
298 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299}
300
301EXPORT_SYMBOL(blk_queue_ordered);
302
303/**
304 * blk_queue_issue_flush_fn - set function for issuing a flush
305 * @q: the request queue
306 * @iff: the function to be called issuing the flush
307 *
308 * Description:
309 * If a driver supports issuing a flush command, the support is notified
310 * to the block layer by defining it through this call.
311 *
312 **/
313void blk_queue_issue_flush_fn(request_queue_t *q, issue_flush_fn *iff)
314{
315 q->issue_flush_fn = iff;
316}
317
318EXPORT_SYMBOL(blk_queue_issue_flush_fn);
319
320/*
321 * Cache flushing for ordered writes handling
322 */
Tejun Heo797e7db2006-01-06 09:51:03 +0100323inline unsigned blk_ordered_cur_seq(request_queue_t *q)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324{
Tejun Heo797e7db2006-01-06 09:51:03 +0100325 if (!q->ordseq)
326 return 0;
327 return 1 << ffz(q->ordseq);
328}
329
330unsigned blk_ordered_req_seq(struct request *rq)
331{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332 request_queue_t *q = rq->q;
333
Tejun Heo797e7db2006-01-06 09:51:03 +0100334 BUG_ON(q->ordseq == 0);
Tejun Heo8922e162005-10-20 16:23:44 +0200335
Tejun Heo797e7db2006-01-06 09:51:03 +0100336 if (rq == &q->pre_flush_rq)
337 return QUEUE_ORDSEQ_PREFLUSH;
338 if (rq == &q->bar_rq)
339 return QUEUE_ORDSEQ_BAR;
340 if (rq == &q->post_flush_rq)
341 return QUEUE_ORDSEQ_POSTFLUSH;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342
Jens Axboe4aff5e22006-08-10 08:44:47 +0200343 if ((rq->cmd_flags & REQ_ORDERED_COLOR) ==
344 (q->orig_bar_rq->cmd_flags & REQ_ORDERED_COLOR))
Tejun Heo797e7db2006-01-06 09:51:03 +0100345 return QUEUE_ORDSEQ_DRAIN;
346 else
347 return QUEUE_ORDSEQ_DONE;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348}
349
Tejun Heo797e7db2006-01-06 09:51:03 +0100350void blk_ordered_complete_seq(request_queue_t *q, unsigned seq, int error)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351{
Tejun Heo797e7db2006-01-06 09:51:03 +0100352 struct request *rq;
353 int uptodate;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354
Tejun Heo797e7db2006-01-06 09:51:03 +0100355 if (error && !q->orderr)
356 q->orderr = error;
Tejun Heo8922e162005-10-20 16:23:44 +0200357
Tejun Heo797e7db2006-01-06 09:51:03 +0100358 BUG_ON(q->ordseq & seq);
359 q->ordseq |= seq;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700360
Tejun Heo797e7db2006-01-06 09:51:03 +0100361 if (blk_ordered_cur_seq(q) != QUEUE_ORDSEQ_DONE)
362 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363
364 /*
Tejun Heo797e7db2006-01-06 09:51:03 +0100365 * Okay, sequence complete.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366 */
Tejun Heo797e7db2006-01-06 09:51:03 +0100367 rq = q->orig_bar_rq;
368 uptodate = q->orderr ? q->orderr : 1;
369
370 q->ordseq = 0;
371
372 end_that_request_first(rq, uptodate, rq->hard_nr_sectors);
373 end_that_request_last(rq, uptodate);
374}
375
376static void pre_flush_end_io(struct request *rq, int error)
377{
378 elv_completed_request(rq->q, rq);
379 blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_PREFLUSH, error);
380}
381
382static void bar_end_io(struct request *rq, int error)
383{
384 elv_completed_request(rq->q, rq);
385 blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_BAR, error);
386}
387
388static void post_flush_end_io(struct request *rq, int error)
389{
390 elv_completed_request(rq->q, rq);
391 blk_ordered_complete_seq(rq->q, QUEUE_ORDSEQ_POSTFLUSH, error);
392}
393
394static void queue_flush(request_queue_t *q, unsigned which)
395{
396 struct request *rq;
397 rq_end_io_fn *end_io;
398
399 if (which == QUEUE_ORDERED_PREFLUSH) {
400 rq = &q->pre_flush_rq;
401 end_io = pre_flush_end_io;
402 } else {
403 rq = &q->post_flush_rq;
404 end_io = post_flush_end_io;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405 }
406
Jens Axboe4aff5e22006-08-10 08:44:47 +0200407 rq->cmd_flags = REQ_HARDBARRIER;
Tejun Heo797e7db2006-01-06 09:51:03 +0100408 rq_init(q, rq);
Tejun Heo797e7db2006-01-06 09:51:03 +0100409 rq->elevator_private = NULL;
Jens Axboec00895a2006-09-30 20:29:12 +0200410 rq->elevator_private2 = NULL;
Tejun Heo797e7db2006-01-06 09:51:03 +0100411 rq->rq_disk = q->bar_rq.rq_disk;
Tejun Heo797e7db2006-01-06 09:51:03 +0100412 rq->end_io = end_io;
413 q->prepare_flush_fn(q, rq);
414
Tejun Heo30e96562006-02-08 01:01:31 -0800415 elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
Tejun Heo797e7db2006-01-06 09:51:03 +0100416}
417
418static inline struct request *start_ordered(request_queue_t *q,
419 struct request *rq)
420{
421 q->bi_size = 0;
422 q->orderr = 0;
423 q->ordered = q->next_ordered;
424 q->ordseq |= QUEUE_ORDSEQ_STARTED;
425
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426 /*
Tejun Heo797e7db2006-01-06 09:51:03 +0100427 * Prep proxy barrier request.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428 */
Tejun Heo797e7db2006-01-06 09:51:03 +0100429 blkdev_dequeue_request(rq);
430 q->orig_bar_rq = rq;
431 rq = &q->bar_rq;
Jens Axboe4aff5e22006-08-10 08:44:47 +0200432 rq->cmd_flags = 0;
Tejun Heo797e7db2006-01-06 09:51:03 +0100433 rq_init(q, rq);
Jens Axboe4aff5e22006-08-10 08:44:47 +0200434 if (bio_data_dir(q->orig_bar_rq->bio) == WRITE)
435 rq->cmd_flags |= REQ_RW;
436 rq->cmd_flags |= q->ordered & QUEUE_ORDERED_FUA ? REQ_FUA : 0;
Tejun Heo797e7db2006-01-06 09:51:03 +0100437 rq->elevator_private = NULL;
Jens Axboec00895a2006-09-30 20:29:12 +0200438 rq->elevator_private2 = NULL;
Tejun Heo797e7db2006-01-06 09:51:03 +0100439 init_request_from_bio(rq, q->orig_bar_rq->bio);
440 rq->end_io = bar_end_io;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441
Tejun Heo797e7db2006-01-06 09:51:03 +0100442 /*
443 * Queue ordered sequence. As we stack them at the head, we
444 * need to queue in reverse order. Note that we rely on that
445 * no fs request uses ELEVATOR_INSERT_FRONT and thus no fs
446 * request gets inbetween ordered sequence.
447 */
448 if (q->ordered & QUEUE_ORDERED_POSTFLUSH)
449 queue_flush(q, QUEUE_ORDERED_POSTFLUSH);
450 else
451 q->ordseq |= QUEUE_ORDSEQ_POSTFLUSH;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452
Tejun Heo30e96562006-02-08 01:01:31 -0800453 elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
Tejun Heo797e7db2006-01-06 09:51:03 +0100454
455 if (q->ordered & QUEUE_ORDERED_PREFLUSH) {
456 queue_flush(q, QUEUE_ORDERED_PREFLUSH);
457 rq = &q->pre_flush_rq;
458 } else
459 q->ordseq |= QUEUE_ORDSEQ_PREFLUSH;
460
461 if ((q->ordered & QUEUE_ORDERED_TAG) || q->in_flight == 0)
462 q->ordseq |= QUEUE_ORDSEQ_DRAIN;
463 else
464 rq = NULL;
465
466 return rq;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467}
468
Tejun Heo797e7db2006-01-06 09:51:03 +0100469int blk_do_ordered(request_queue_t *q, struct request **rqp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700470{
Jens Axboe9a7a67a2006-02-04 23:27:38 -0800471 struct request *rq = *rqp;
Tejun Heo797e7db2006-01-06 09:51:03 +0100472 int is_barrier = blk_fs_request(rq) && blk_barrier_rq(rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700473
Tejun Heo797e7db2006-01-06 09:51:03 +0100474 if (!q->ordseq) {
475 if (!is_barrier)
476 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477
Tejun Heo797e7db2006-01-06 09:51:03 +0100478 if (q->next_ordered != QUEUE_ORDERED_NONE) {
479 *rqp = start_ordered(q, rq);
480 return 1;
481 } else {
482 /*
483 * This can happen when the queue switches to
484 * ORDERED_NONE while this request is on it.
485 */
486 blkdev_dequeue_request(rq);
487 end_that_request_first(rq, -EOPNOTSUPP,
488 rq->hard_nr_sectors);
489 end_that_request_last(rq, -EOPNOTSUPP);
490 *rqp = NULL;
491 return 0;
492 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494
Jens Axboe9a7a67a2006-02-04 23:27:38 -0800495 /*
496 * Ordered sequence in progress
497 */
498
499 /* Special requests are not subject to ordering rules. */
500 if (!blk_fs_request(rq) &&
501 rq != &q->pre_flush_rq && rq != &q->post_flush_rq)
502 return 1;
503
Tejun Heo797e7db2006-01-06 09:51:03 +0100504 if (q->ordered & QUEUE_ORDERED_TAG) {
Jens Axboe9a7a67a2006-02-04 23:27:38 -0800505 /* Ordered by tag. Blocking the next barrier is enough. */
Tejun Heo797e7db2006-01-06 09:51:03 +0100506 if (is_barrier && rq != &q->bar_rq)
507 *rqp = NULL;
Jens Axboe9a7a67a2006-02-04 23:27:38 -0800508 } else {
509 /* Ordered by draining. Wait for turn. */
510 WARN_ON(blk_ordered_req_seq(rq) < blk_ordered_cur_seq(q));
511 if (blk_ordered_req_seq(rq) > blk_ordered_cur_seq(q))
512 *rqp = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513 }
514
515 return 1;
516}
517
Tejun Heo797e7db2006-01-06 09:51:03 +0100518static int flush_dry_bio_endio(struct bio *bio, unsigned int bytes, int error)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519{
Tejun Heo797e7db2006-01-06 09:51:03 +0100520 request_queue_t *q = bio->bi_private;
521 struct bio_vec *bvec;
522 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700523
Tejun Heo797e7db2006-01-06 09:51:03 +0100524 /*
525 * This is dry run, restore bio_sector and size. We'll finish
526 * this request again with the original bi_end_io after an
527 * error occurs or post flush is complete.
528 */
529 q->bi_size += bytes;
530
531 if (bio->bi_size)
532 return 1;
533
534 /* Rewind bvec's */
535 bio->bi_idx = 0;
536 bio_for_each_segment(bvec, bio, i) {
537 bvec->bv_len += bvec->bv_offset;
538 bvec->bv_offset = 0;
539 }
540
541 /* Reset bio */
542 set_bit(BIO_UPTODATE, &bio->bi_flags);
543 bio->bi_size = q->bi_size;
544 bio->bi_sector -= (q->bi_size >> 9);
545 q->bi_size = 0;
546
547 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548}
Tejun Heo797e7db2006-01-06 09:51:03 +0100549
Jens Axboe1ea25ecb2006-07-18 22:24:11 +0200550static int ordered_bio_endio(struct request *rq, struct bio *bio,
551 unsigned int nbytes, int error)
Tejun Heo797e7db2006-01-06 09:51:03 +0100552{
553 request_queue_t *q = rq->q;
554 bio_end_io_t *endio;
555 void *private;
556
557 if (&q->bar_rq != rq)
558 return 0;
559
560 /*
561 * Okay, this is the barrier request in progress, dry finish it.
562 */
563 if (error && !q->orderr)
564 q->orderr = error;
565
566 endio = bio->bi_end_io;
567 private = bio->bi_private;
568 bio->bi_end_io = flush_dry_bio_endio;
569 bio->bi_private = q;
570
571 bio_endio(bio, nbytes, error);
572
573 bio->bi_end_io = endio;
574 bio->bi_private = private;
575
576 return 1;
577}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700578
579/**
580 * blk_queue_bounce_limit - set bounce buffer limit for queue
581 * @q: the request queue for the device
582 * @dma_addr: bus address limit
583 *
584 * Description:
585 * Different hardware can have different requirements as to what pages
586 * it can do I/O directly to. A low level driver can call
587 * blk_queue_bounce_limit to have lower memory pages allocated as bounce
Andi Kleen5ee1af92006-03-08 17:57:26 -0800588 * buffers for doing I/O to pages residing above @page.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589 **/
590void blk_queue_bounce_limit(request_queue_t *q, u64 dma_addr)
591{
592 unsigned long bounce_pfn = dma_addr >> PAGE_SHIFT;
Andi Kleen5ee1af92006-03-08 17:57:26 -0800593 int dma = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594
Andi Kleen5ee1af92006-03-08 17:57:26 -0800595 q->bounce_gfp = GFP_NOIO;
596#if BITS_PER_LONG == 64
597 /* Assume anything <= 4GB can be handled by IOMMU.
598 Actually some IOMMUs can handle everything, but I don't
599 know of a way to test this here. */
Andi Kleen82697302006-06-21 14:48:09 +0200600 if (bounce_pfn < (min_t(u64,0xffffffff,BLK_BOUNCE_HIGH) >> PAGE_SHIFT))
Andi Kleen5ee1af92006-03-08 17:57:26 -0800601 dma = 1;
602 q->bounce_pfn = max_low_pfn;
603#else
604 if (bounce_pfn < blk_max_low_pfn)
605 dma = 1;
606 q->bounce_pfn = bounce_pfn;
607#endif
608 if (dma) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700609 init_emergency_isa_pool();
610 q->bounce_gfp = GFP_NOIO | GFP_DMA;
Andi Kleen5ee1af92006-03-08 17:57:26 -0800611 q->bounce_pfn = bounce_pfn;
612 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700613}
614
615EXPORT_SYMBOL(blk_queue_bounce_limit);
616
617/**
618 * blk_queue_max_sectors - set max sectors for a request for this queue
619 * @q: the request queue for the device
620 * @max_sectors: max sectors in the usual 512b unit
621 *
622 * Description:
623 * Enables a low level driver to set an upper limit on the size of
624 * received requests.
625 **/
Jens Axboe2cb2e142006-01-17 09:04:32 +0100626void blk_queue_max_sectors(request_queue_t *q, unsigned int max_sectors)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700627{
628 if ((max_sectors << 9) < PAGE_CACHE_SIZE) {
629 max_sectors = 1 << (PAGE_CACHE_SHIFT - 9);
630 printk("%s: set to minimum %d\n", __FUNCTION__, max_sectors);
631 }
632
Mike Christiedefd94b2005-12-05 02:37:06 -0600633 if (BLK_DEF_MAX_SECTORS > max_sectors)
634 q->max_hw_sectors = q->max_sectors = max_sectors;
635 else {
636 q->max_sectors = BLK_DEF_MAX_SECTORS;
637 q->max_hw_sectors = max_sectors;
638 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639}
640
641EXPORT_SYMBOL(blk_queue_max_sectors);
642
643/**
644 * blk_queue_max_phys_segments - set max phys segments for a request for this queue
645 * @q: the request queue for the device
646 * @max_segments: max number of segments
647 *
648 * Description:
649 * Enables a low level driver to set an upper limit on the number of
650 * physical data segments in a request. This would be the largest sized
651 * scatter list the driver could handle.
652 **/
653void blk_queue_max_phys_segments(request_queue_t *q, unsigned short max_segments)
654{
655 if (!max_segments) {
656 max_segments = 1;
657 printk("%s: set to minimum %d\n", __FUNCTION__, max_segments);
658 }
659
660 q->max_phys_segments = max_segments;
661}
662
663EXPORT_SYMBOL(blk_queue_max_phys_segments);
664
665/**
666 * blk_queue_max_hw_segments - set max hw segments for a request for this queue
667 * @q: the request queue for the device
668 * @max_segments: max number of segments
669 *
670 * Description:
671 * Enables a low level driver to set an upper limit on the number of
672 * hw data segments in a request. This would be the largest number of
673 * address/length pairs the host adapter can actually give as once
674 * to the device.
675 **/
676void blk_queue_max_hw_segments(request_queue_t *q, unsigned short max_segments)
677{
678 if (!max_segments) {
679 max_segments = 1;
680 printk("%s: set to minimum %d\n", __FUNCTION__, max_segments);
681 }
682
683 q->max_hw_segments = max_segments;
684}
685
686EXPORT_SYMBOL(blk_queue_max_hw_segments);
687
688/**
689 * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg
690 * @q: the request queue for the device
691 * @max_size: max size of segment in bytes
692 *
693 * Description:
694 * Enables a low level driver to set an upper limit on the size of a
695 * coalesced segment
696 **/
697void blk_queue_max_segment_size(request_queue_t *q, unsigned int max_size)
698{
699 if (max_size < PAGE_CACHE_SIZE) {
700 max_size = PAGE_CACHE_SIZE;
701 printk("%s: set to minimum %d\n", __FUNCTION__, max_size);
702 }
703
704 q->max_segment_size = max_size;
705}
706
707EXPORT_SYMBOL(blk_queue_max_segment_size);
708
709/**
710 * blk_queue_hardsect_size - set hardware sector size for the queue
711 * @q: the request queue for the device
712 * @size: the hardware sector size, in bytes
713 *
714 * Description:
715 * This should typically be set to the lowest possible sector size
716 * that the hardware can operate on (possible without reverting to
717 * even internal read-modify-write operations). Usually the default
718 * of 512 covers most hardware.
719 **/
720void blk_queue_hardsect_size(request_queue_t *q, unsigned short size)
721{
722 q->hardsect_size = size;
723}
724
725EXPORT_SYMBOL(blk_queue_hardsect_size);
726
727/*
728 * Returns the minimum that is _not_ zero, unless both are zero.
729 */
730#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
731
732/**
733 * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
734 * @t: the stacking driver (top)
735 * @b: the underlying device (bottom)
736 **/
737void blk_queue_stack_limits(request_queue_t *t, request_queue_t *b)
738{
739 /* zero is "infinity" */
Mike Christiedefd94b2005-12-05 02:37:06 -0600740 t->max_sectors = min_not_zero(t->max_sectors,b->max_sectors);
741 t->max_hw_sectors = min_not_zero(t->max_hw_sectors,b->max_hw_sectors);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700742
743 t->max_phys_segments = min(t->max_phys_segments,b->max_phys_segments);
744 t->max_hw_segments = min(t->max_hw_segments,b->max_hw_segments);
745 t->max_segment_size = min(t->max_segment_size,b->max_segment_size);
746 t->hardsect_size = max(t->hardsect_size,b->hardsect_size);
NeilBrown89e5c8b2006-03-27 01:18:02 -0800747 if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags))
748 clear_bit(QUEUE_FLAG_CLUSTER, &t->queue_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700749}
750
751EXPORT_SYMBOL(blk_queue_stack_limits);
752
753/**
754 * blk_queue_segment_boundary - set boundary rules for segment merging
755 * @q: the request queue for the device
756 * @mask: the memory boundary mask
757 **/
758void blk_queue_segment_boundary(request_queue_t *q, unsigned long mask)
759{
760 if (mask < PAGE_CACHE_SIZE - 1) {
761 mask = PAGE_CACHE_SIZE - 1;
762 printk("%s: set to minimum %lx\n", __FUNCTION__, mask);
763 }
764
765 q->seg_boundary_mask = mask;
766}
767
768EXPORT_SYMBOL(blk_queue_segment_boundary);
769
770/**
771 * blk_queue_dma_alignment - set dma length and memory alignment
772 * @q: the request queue for the device
773 * @mask: alignment mask
774 *
775 * description:
776 * set required memory and length aligment for direct dma transactions.
777 * this is used when buiding direct io requests for the queue.
778 *
779 **/
780void blk_queue_dma_alignment(request_queue_t *q, int mask)
781{
782 q->dma_alignment = mask;
783}
784
785EXPORT_SYMBOL(blk_queue_dma_alignment);
786
787/**
788 * blk_queue_find_tag - find a request by its tag and queue
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789 * @q: The request queue for the device
790 * @tag: The tag of the request
791 *
792 * Notes:
793 * Should be used when a device returns a tag and you want to match
794 * it with a request.
795 *
796 * no locks need be held.
797 **/
798struct request *blk_queue_find_tag(request_queue_t *q, int tag)
799{
David C Somayajuluf583f492006-10-04 08:27:25 +0200800 return blk_map_queue_find_tag(q->queue_tags, tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700801}
802
803EXPORT_SYMBOL(blk_queue_find_tag);
804
805/**
James Bottomley492dfb42006-08-30 15:48:45 -0400806 * __blk_free_tags - release a given set of tag maintenance info
807 * @bqt: the tag map to free
808 *
809 * Tries to free the specified @bqt@. Returns true if it was
810 * actually freed and false if there are still references using it
811 */
812static int __blk_free_tags(struct blk_queue_tag *bqt)
813{
814 int retval;
815
816 retval = atomic_dec_and_test(&bqt->refcnt);
817 if (retval) {
818 BUG_ON(bqt->busy);
819 BUG_ON(!list_empty(&bqt->busy_list));
820
821 kfree(bqt->tag_index);
822 bqt->tag_index = NULL;
823
824 kfree(bqt->tag_map);
825 bqt->tag_map = NULL;
826
827 kfree(bqt);
828
829 }
830
831 return retval;
832}
833
834/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700835 * __blk_queue_free_tags - release tag maintenance info
836 * @q: the request queue for the device
837 *
838 * Notes:
839 * blk_cleanup_queue() will take care of calling this function, if tagging
840 * has been used. So there's no need to call this directly.
841 **/
842static void __blk_queue_free_tags(request_queue_t *q)
843{
844 struct blk_queue_tag *bqt = q->queue_tags;
845
846 if (!bqt)
847 return;
848
James Bottomley492dfb42006-08-30 15:48:45 -0400849 __blk_free_tags(bqt);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700850
851 q->queue_tags = NULL;
852 q->queue_flags &= ~(1 << QUEUE_FLAG_QUEUED);
853}
854
James Bottomley492dfb42006-08-30 15:48:45 -0400855
856/**
857 * blk_free_tags - release a given set of tag maintenance info
858 * @bqt: the tag map to free
859 *
860 * For externally managed @bqt@ frees the map. Callers of this
861 * function must guarantee to have released all the queues that
862 * might have been using this tag map.
863 */
864void blk_free_tags(struct blk_queue_tag *bqt)
865{
866 if (unlikely(!__blk_free_tags(bqt)))
867 BUG();
868}
869EXPORT_SYMBOL(blk_free_tags);
870
Linus Torvalds1da177e2005-04-16 15:20:36 -0700871/**
872 * blk_queue_free_tags - release tag maintenance info
873 * @q: the request queue for the device
874 *
875 * Notes:
876 * This is used to disabled tagged queuing to a device, yet leave
877 * queue in function.
878 **/
879void blk_queue_free_tags(request_queue_t *q)
880{
881 clear_bit(QUEUE_FLAG_QUEUED, &q->queue_flags);
882}
883
884EXPORT_SYMBOL(blk_queue_free_tags);
885
886static int
887init_tag_map(request_queue_t *q, struct blk_queue_tag *tags, int depth)
888{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700889 struct request **tag_index;
890 unsigned long *tag_map;
Tejun Heofa72b902005-06-23 00:08:49 -0700891 int nr_ulongs;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700892
James Bottomley492dfb42006-08-30 15:48:45 -0400893 if (q && depth > q->nr_requests * 2) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700894 depth = q->nr_requests * 2;
895 printk(KERN_ERR "%s: adjusted depth to %d\n",
896 __FUNCTION__, depth);
897 }
898
Jens Axboef68110f2006-03-08 13:31:44 +0100899 tag_index = kzalloc(depth * sizeof(struct request *), GFP_ATOMIC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700900 if (!tag_index)
901 goto fail;
902
Tejun Heof7d37d02005-06-23 00:08:50 -0700903 nr_ulongs = ALIGN(depth, BITS_PER_LONG) / BITS_PER_LONG;
Jens Axboef68110f2006-03-08 13:31:44 +0100904 tag_map = kzalloc(nr_ulongs * sizeof(unsigned long), GFP_ATOMIC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700905 if (!tag_map)
906 goto fail;
907
Tejun Heoba025082005-08-05 13:28:11 -0700908 tags->real_max_depth = depth;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700909 tags->max_depth = depth;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700910 tags->tag_index = tag_index;
911 tags->tag_map = tag_map;
912
Linus Torvalds1da177e2005-04-16 15:20:36 -0700913 return 0;
914fail:
915 kfree(tag_index);
916 return -ENOMEM;
917}
918
James Bottomley492dfb42006-08-30 15:48:45 -0400919static struct blk_queue_tag *__blk_queue_init_tags(struct request_queue *q,
920 int depth)
921{
922 struct blk_queue_tag *tags;
923
924 tags = kmalloc(sizeof(struct blk_queue_tag), GFP_ATOMIC);
925 if (!tags)
926 goto fail;
927
928 if (init_tag_map(q, tags, depth))
929 goto fail;
930
931 INIT_LIST_HEAD(&tags->busy_list);
932 tags->busy = 0;
933 atomic_set(&tags->refcnt, 1);
934 return tags;
935fail:
936 kfree(tags);
937 return NULL;
938}
939
940/**
941 * blk_init_tags - initialize the tag info for an external tag map
942 * @depth: the maximum queue depth supported
943 * @tags: the tag to use
944 **/
945struct blk_queue_tag *blk_init_tags(int depth)
946{
947 return __blk_queue_init_tags(NULL, depth);
948}
949EXPORT_SYMBOL(blk_init_tags);
950
Linus Torvalds1da177e2005-04-16 15:20:36 -0700951/**
952 * blk_queue_init_tags - initialize the queue tag info
953 * @q: the request queue for the device
954 * @depth: the maximum queue depth supported
955 * @tags: the tag to use
956 **/
957int blk_queue_init_tags(request_queue_t *q, int depth,
958 struct blk_queue_tag *tags)
959{
960 int rc;
961
962 BUG_ON(tags && q->queue_tags && tags != q->queue_tags);
963
964 if (!tags && !q->queue_tags) {
James Bottomley492dfb42006-08-30 15:48:45 -0400965 tags = __blk_queue_init_tags(q, depth);
966
Linus Torvalds1da177e2005-04-16 15:20:36 -0700967 if (!tags)
968 goto fail;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700969 } else if (q->queue_tags) {
970 if ((rc = blk_queue_resize_tags(q, depth)))
971 return rc;
972 set_bit(QUEUE_FLAG_QUEUED, &q->queue_flags);
973 return 0;
974 } else
975 atomic_inc(&tags->refcnt);
976
977 /*
978 * assign it, all done
979 */
980 q->queue_tags = tags;
981 q->queue_flags |= (1 << QUEUE_FLAG_QUEUED);
982 return 0;
983fail:
984 kfree(tags);
985 return -ENOMEM;
986}
987
988EXPORT_SYMBOL(blk_queue_init_tags);
989
990/**
991 * blk_queue_resize_tags - change the queueing depth
992 * @q: the request queue for the device
993 * @new_depth: the new max command queueing depth
994 *
995 * Notes:
996 * Must be called with the queue lock held.
997 **/
998int blk_queue_resize_tags(request_queue_t *q, int new_depth)
999{
1000 struct blk_queue_tag *bqt = q->queue_tags;
1001 struct request **tag_index;
1002 unsigned long *tag_map;
Tejun Heofa72b902005-06-23 00:08:49 -07001003 int max_depth, nr_ulongs;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001004
1005 if (!bqt)
1006 return -ENXIO;
1007
1008 /*
Tejun Heoba025082005-08-05 13:28:11 -07001009 * if we already have large enough real_max_depth. just
1010 * adjust max_depth. *NOTE* as requests with tag value
1011 * between new_depth and real_max_depth can be in-flight, tag
1012 * map can not be shrunk blindly here.
1013 */
1014 if (new_depth <= bqt->real_max_depth) {
1015 bqt->max_depth = new_depth;
1016 return 0;
1017 }
1018
1019 /*
James Bottomley492dfb42006-08-30 15:48:45 -04001020 * Currently cannot replace a shared tag map with a new
1021 * one, so error out if this is the case
1022 */
1023 if (atomic_read(&bqt->refcnt) != 1)
1024 return -EBUSY;
1025
1026 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001027 * save the old state info, so we can copy it back
1028 */
1029 tag_index = bqt->tag_index;
1030 tag_map = bqt->tag_map;
Tejun Heoba025082005-08-05 13:28:11 -07001031 max_depth = bqt->real_max_depth;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001032
1033 if (init_tag_map(q, bqt, new_depth))
1034 return -ENOMEM;
1035
1036 memcpy(bqt->tag_index, tag_index, max_depth * sizeof(struct request *));
Tejun Heof7d37d02005-06-23 00:08:50 -07001037 nr_ulongs = ALIGN(max_depth, BITS_PER_LONG) / BITS_PER_LONG;
Tejun Heofa72b902005-06-23 00:08:49 -07001038 memcpy(bqt->tag_map, tag_map, nr_ulongs * sizeof(unsigned long));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001039
1040 kfree(tag_index);
1041 kfree(tag_map);
1042 return 0;
1043}
1044
1045EXPORT_SYMBOL(blk_queue_resize_tags);
1046
1047/**
1048 * blk_queue_end_tag - end tag operations for a request
1049 * @q: the request queue for the device
1050 * @rq: the request that has completed
1051 *
1052 * Description:
1053 * Typically called when end_that_request_first() returns 0, meaning
1054 * all transfers have been done for a request. It's important to call
1055 * this function before end_that_request_last(), as that will put the
1056 * request back on the free list thus corrupting the internal tag list.
1057 *
1058 * Notes:
1059 * queue lock must be held.
1060 **/
1061void blk_queue_end_tag(request_queue_t *q, struct request *rq)
1062{
1063 struct blk_queue_tag *bqt = q->queue_tags;
1064 int tag = rq->tag;
1065
1066 BUG_ON(tag == -1);
1067
Tejun Heoba025082005-08-05 13:28:11 -07001068 if (unlikely(tag >= bqt->real_max_depth))
Tejun Heo040c9282005-06-23 00:08:51 -07001069 /*
1070 * This can happen after tag depth has been reduced.
1071 * FIXME: how about a warning or info message here?
1072 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001073 return;
1074
1075 if (unlikely(!__test_and_clear_bit(tag, bqt->tag_map))) {
Tejun Heo040c9282005-06-23 00:08:51 -07001076 printk(KERN_ERR "%s: attempt to clear non-busy tag (%d)\n",
1077 __FUNCTION__, tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001078 return;
1079 }
1080
1081 list_del_init(&rq->queuelist);
Jens Axboe4aff5e22006-08-10 08:44:47 +02001082 rq->cmd_flags &= ~REQ_QUEUED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001083 rq->tag = -1;
1084
1085 if (unlikely(bqt->tag_index[tag] == NULL))
Tejun Heo040c9282005-06-23 00:08:51 -07001086 printk(KERN_ERR "%s: tag %d is missing\n",
1087 __FUNCTION__, tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001088
1089 bqt->tag_index[tag] = NULL;
1090 bqt->busy--;
1091}
1092
1093EXPORT_SYMBOL(blk_queue_end_tag);
1094
1095/**
1096 * blk_queue_start_tag - find a free tag and assign it
1097 * @q: the request queue for the device
1098 * @rq: the block request that needs tagging
1099 *
1100 * Description:
1101 * This can either be used as a stand-alone helper, or possibly be
1102 * assigned as the queue &prep_rq_fn (in which case &struct request
1103 * automagically gets a tag assigned). Note that this function
1104 * assumes that any type of request can be queued! if this is not
1105 * true for your device, you must check the request type before
1106 * calling this function. The request will also be removed from
1107 * the request queue, so it's the drivers responsibility to readd
1108 * it if it should need to be restarted for some reason.
1109 *
1110 * Notes:
1111 * queue lock must be held.
1112 **/
1113int blk_queue_start_tag(request_queue_t *q, struct request *rq)
1114{
1115 struct blk_queue_tag *bqt = q->queue_tags;
Tejun Heo2bf0fda2005-06-23 00:08:48 -07001116 int tag;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001117
Jens Axboe4aff5e22006-08-10 08:44:47 +02001118 if (unlikely((rq->cmd_flags & REQ_QUEUED))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001119 printk(KERN_ERR
Tejun Heo040c9282005-06-23 00:08:51 -07001120 "%s: request %p for device [%s] already tagged %d",
1121 __FUNCTION__, rq,
1122 rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001123 BUG();
1124 }
1125
Jens Axboe059af492006-09-21 20:37:22 +02001126 /*
1127 * Protect against shared tag maps, as we may not have exclusive
1128 * access to the tag map.
1129 */
1130 do {
1131 tag = find_first_zero_bit(bqt->tag_map, bqt->max_depth);
1132 if (tag >= bqt->max_depth)
1133 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001134
Jens Axboe059af492006-09-21 20:37:22 +02001135 } while (test_and_set_bit(tag, bqt->tag_map));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001136
Jens Axboe4aff5e22006-08-10 08:44:47 +02001137 rq->cmd_flags |= REQ_QUEUED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001138 rq->tag = tag;
1139 bqt->tag_index[tag] = rq;
1140 blkdev_dequeue_request(rq);
1141 list_add(&rq->queuelist, &bqt->busy_list);
1142 bqt->busy++;
1143 return 0;
1144}
1145
1146EXPORT_SYMBOL(blk_queue_start_tag);
1147
1148/**
1149 * blk_queue_invalidate_tags - invalidate all pending tags
1150 * @q: the request queue for the device
1151 *
1152 * Description:
1153 * Hardware conditions may dictate a need to stop all pending requests.
1154 * In this case, we will safely clear the block side of the tag queue and
1155 * readd all requests to the request queue in the right order.
1156 *
1157 * Notes:
1158 * queue lock must be held.
1159 **/
1160void blk_queue_invalidate_tags(request_queue_t *q)
1161{
1162 struct blk_queue_tag *bqt = q->queue_tags;
1163 struct list_head *tmp, *n;
1164 struct request *rq;
1165
1166 list_for_each_safe(tmp, n, &bqt->busy_list) {
1167 rq = list_entry_rq(tmp);
1168
1169 if (rq->tag == -1) {
Tejun Heo040c9282005-06-23 00:08:51 -07001170 printk(KERN_ERR
1171 "%s: bad tag found on list\n", __FUNCTION__);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001172 list_del_init(&rq->queuelist);
Jens Axboe4aff5e22006-08-10 08:44:47 +02001173 rq->cmd_flags &= ~REQ_QUEUED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001174 } else
1175 blk_queue_end_tag(q, rq);
1176
Jens Axboe4aff5e22006-08-10 08:44:47 +02001177 rq->cmd_flags &= ~REQ_STARTED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001178 __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0);
1179 }
1180}
1181
1182EXPORT_SYMBOL(blk_queue_invalidate_tags);
1183
Linus Torvalds1da177e2005-04-16 15:20:36 -07001184void blk_dump_rq_flags(struct request *rq, char *msg)
1185{
1186 int bit;
1187
Jens Axboe4aff5e22006-08-10 08:44:47 +02001188 printk("%s: dev %s: type=%x, flags=%x\n", msg,
1189 rq->rq_disk ? rq->rq_disk->disk_name : "?", rq->cmd_type,
1190 rq->cmd_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001191
1192 printk("\nsector %llu, nr/cnr %lu/%u\n", (unsigned long long)rq->sector,
1193 rq->nr_sectors,
1194 rq->current_nr_sectors);
1195 printk("bio %p, biotail %p, buffer %p, data %p, len %u\n", rq->bio, rq->biotail, rq->buffer, rq->data, rq->data_len);
1196
Jens Axboe4aff5e22006-08-10 08:44:47 +02001197 if (blk_pc_request(rq)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001198 printk("cdb: ");
1199 for (bit = 0; bit < sizeof(rq->cmd); bit++)
1200 printk("%02x ", rq->cmd[bit]);
1201 printk("\n");
1202 }
1203}
1204
1205EXPORT_SYMBOL(blk_dump_rq_flags);
1206
1207void blk_recount_segments(request_queue_t *q, struct bio *bio)
1208{
1209 struct bio_vec *bv, *bvprv = NULL;
1210 int i, nr_phys_segs, nr_hw_segs, seg_size, hw_seg_size, cluster;
1211 int high, highprv = 1;
1212
1213 if (unlikely(!bio->bi_io_vec))
1214 return;
1215
1216 cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
1217 hw_seg_size = seg_size = nr_phys_segs = nr_hw_segs = 0;
1218 bio_for_each_segment(bv, bio, i) {
1219 /*
1220 * the trick here is making sure that a high page is never
1221 * considered part of another segment, since that might
1222 * change with the bounce page.
1223 */
1224 high = page_to_pfn(bv->bv_page) >= q->bounce_pfn;
1225 if (high || highprv)
1226 goto new_hw_segment;
1227 if (cluster) {
1228 if (seg_size + bv->bv_len > q->max_segment_size)
1229 goto new_segment;
1230 if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv))
1231 goto new_segment;
1232 if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv))
1233 goto new_segment;
1234 if (BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len))
1235 goto new_hw_segment;
1236
1237 seg_size += bv->bv_len;
1238 hw_seg_size += bv->bv_len;
1239 bvprv = bv;
1240 continue;
1241 }
1242new_segment:
1243 if (BIOVEC_VIRT_MERGEABLE(bvprv, bv) &&
1244 !BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len)) {
1245 hw_seg_size += bv->bv_len;
1246 } else {
1247new_hw_segment:
1248 if (hw_seg_size > bio->bi_hw_front_size)
1249 bio->bi_hw_front_size = hw_seg_size;
1250 hw_seg_size = BIOVEC_VIRT_START_SIZE(bv) + bv->bv_len;
1251 nr_hw_segs++;
1252 }
1253
1254 nr_phys_segs++;
1255 bvprv = bv;
1256 seg_size = bv->bv_len;
1257 highprv = high;
1258 }
1259 if (hw_seg_size > bio->bi_hw_back_size)
1260 bio->bi_hw_back_size = hw_seg_size;
1261 if (nr_hw_segs == 1 && hw_seg_size > bio->bi_hw_front_size)
1262 bio->bi_hw_front_size = hw_seg_size;
1263 bio->bi_phys_segments = nr_phys_segs;
1264 bio->bi_hw_segments = nr_hw_segs;
1265 bio->bi_flags |= (1 << BIO_SEG_VALID);
1266}
Neil Brown387bb172007-02-08 14:20:29 -08001267EXPORT_SYMBOL(blk_recount_segments);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001268
Adrian Bunk93d17d32005-06-25 14:59:10 -07001269static int blk_phys_contig_segment(request_queue_t *q, struct bio *bio,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001270 struct bio *nxt)
1271{
1272 if (!(q->queue_flags & (1 << QUEUE_FLAG_CLUSTER)))
1273 return 0;
1274
1275 if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)))
1276 return 0;
1277 if (bio->bi_size + nxt->bi_size > q->max_segment_size)
1278 return 0;
1279
1280 /*
1281 * bio and nxt are contigous in memory, check if the queue allows
1282 * these two to be merged into one
1283 */
1284 if (BIO_SEG_BOUNDARY(q, bio, nxt))
1285 return 1;
1286
1287 return 0;
1288}
1289
Adrian Bunk93d17d32005-06-25 14:59:10 -07001290static int blk_hw_contig_segment(request_queue_t *q, struct bio *bio,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001291 struct bio *nxt)
1292{
1293 if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
1294 blk_recount_segments(q, bio);
1295 if (unlikely(!bio_flagged(nxt, BIO_SEG_VALID)))
1296 blk_recount_segments(q, nxt);
1297 if (!BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)) ||
1298 BIOVEC_VIRT_OVERSIZE(bio->bi_hw_front_size + bio->bi_hw_back_size))
1299 return 0;
1300 if (bio->bi_size + nxt->bi_size > q->max_segment_size)
1301 return 0;
1302
1303 return 1;
1304}
1305
Linus Torvalds1da177e2005-04-16 15:20:36 -07001306/*
1307 * map a request to scatterlist, return number of sg entries setup. Caller
1308 * must make sure sg can hold rq->nr_phys_segments entries
1309 */
1310int blk_rq_map_sg(request_queue_t *q, struct request *rq, struct scatterlist *sg)
1311{
1312 struct bio_vec *bvec, *bvprv;
1313 struct bio *bio;
1314 int nsegs, i, cluster;
1315
1316 nsegs = 0;
1317 cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
1318
1319 /*
1320 * for each bio in rq
1321 */
1322 bvprv = NULL;
1323 rq_for_each_bio(bio, rq) {
1324 /*
1325 * for each segment in bio
1326 */
1327 bio_for_each_segment(bvec, bio, i) {
1328 int nbytes = bvec->bv_len;
1329
1330 if (bvprv && cluster) {
1331 if (sg[nsegs - 1].length + nbytes > q->max_segment_size)
1332 goto new_segment;
1333
1334 if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec))
1335 goto new_segment;
1336 if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec))
1337 goto new_segment;
1338
1339 sg[nsegs - 1].length += nbytes;
1340 } else {
1341new_segment:
1342 memset(&sg[nsegs],0,sizeof(struct scatterlist));
1343 sg[nsegs].page = bvec->bv_page;
1344 sg[nsegs].length = nbytes;
1345 sg[nsegs].offset = bvec->bv_offset;
1346
1347 nsegs++;
1348 }
1349 bvprv = bvec;
1350 } /* segments in bio */
1351 } /* bios in rq */
1352
1353 return nsegs;
1354}
1355
1356EXPORT_SYMBOL(blk_rq_map_sg);
1357
1358/*
1359 * the standard queue merge functions, can be overridden with device
1360 * specific ones if so desired
1361 */
1362
1363static inline int ll_new_mergeable(request_queue_t *q,
1364 struct request *req,
1365 struct bio *bio)
1366{
1367 int nr_phys_segs = bio_phys_segments(q, bio);
1368
1369 if (req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) {
Jens Axboe4aff5e22006-08-10 08:44:47 +02001370 req->cmd_flags |= REQ_NOMERGE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001371 if (req == q->last_merge)
1372 q->last_merge = NULL;
1373 return 0;
1374 }
1375
1376 /*
1377 * A hw segment is just getting larger, bump just the phys
1378 * counter.
1379 */
1380 req->nr_phys_segments += nr_phys_segs;
1381 return 1;
1382}
1383
1384static inline int ll_new_hw_segment(request_queue_t *q,
1385 struct request *req,
1386 struct bio *bio)
1387{
1388 int nr_hw_segs = bio_hw_segments(q, bio);
1389 int nr_phys_segs = bio_phys_segments(q, bio);
1390
1391 if (req->nr_hw_segments + nr_hw_segs > q->max_hw_segments
1392 || req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) {
Jens Axboe4aff5e22006-08-10 08:44:47 +02001393 req->cmd_flags |= REQ_NOMERGE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001394 if (req == q->last_merge)
1395 q->last_merge = NULL;
1396 return 0;
1397 }
1398
1399 /*
1400 * This will form the start of a new hw segment. Bump both
1401 * counters.
1402 */
1403 req->nr_hw_segments += nr_hw_segs;
1404 req->nr_phys_segments += nr_phys_segs;
1405 return 1;
1406}
1407
Jens Axboe1aa4f242006-12-19 08:33:11 +01001408int ll_back_merge_fn(request_queue_t *q, struct request *req, struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001409{
Mike Christiedefd94b2005-12-05 02:37:06 -06001410 unsigned short max_sectors;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001411 int len;
1412
Mike Christiedefd94b2005-12-05 02:37:06 -06001413 if (unlikely(blk_pc_request(req)))
1414 max_sectors = q->max_hw_sectors;
1415 else
1416 max_sectors = q->max_sectors;
1417
1418 if (req->nr_sectors + bio_sectors(bio) > max_sectors) {
Jens Axboe4aff5e22006-08-10 08:44:47 +02001419 req->cmd_flags |= REQ_NOMERGE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001420 if (req == q->last_merge)
1421 q->last_merge = NULL;
1422 return 0;
1423 }
1424 if (unlikely(!bio_flagged(req->biotail, BIO_SEG_VALID)))
1425 blk_recount_segments(q, req->biotail);
1426 if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
1427 blk_recount_segments(q, bio);
1428 len = req->biotail->bi_hw_back_size + bio->bi_hw_front_size;
1429 if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req->biotail), __BVEC_START(bio)) &&
1430 !BIOVEC_VIRT_OVERSIZE(len)) {
1431 int mergeable = ll_new_mergeable(q, req, bio);
1432
1433 if (mergeable) {
1434 if (req->nr_hw_segments == 1)
1435 req->bio->bi_hw_front_size = len;
1436 if (bio->bi_hw_segments == 1)
1437 bio->bi_hw_back_size = len;
1438 }
1439 return mergeable;
1440 }
1441
1442 return ll_new_hw_segment(q, req, bio);
1443}
Jens Axboe1aa4f242006-12-19 08:33:11 +01001444EXPORT_SYMBOL(ll_back_merge_fn);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001445
1446static int ll_front_merge_fn(request_queue_t *q, struct request *req,
1447 struct bio *bio)
1448{
Mike Christiedefd94b2005-12-05 02:37:06 -06001449 unsigned short max_sectors;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001450 int len;
1451
Mike Christiedefd94b2005-12-05 02:37:06 -06001452 if (unlikely(blk_pc_request(req)))
1453 max_sectors = q->max_hw_sectors;
1454 else
1455 max_sectors = q->max_sectors;
1456
1457
1458 if (req->nr_sectors + bio_sectors(bio) > max_sectors) {
Jens Axboe4aff5e22006-08-10 08:44:47 +02001459 req->cmd_flags |= REQ_NOMERGE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001460 if (req == q->last_merge)
1461 q->last_merge = NULL;
1462 return 0;
1463 }
1464 len = bio->bi_hw_back_size + req->bio->bi_hw_front_size;
1465 if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
1466 blk_recount_segments(q, bio);
1467 if (unlikely(!bio_flagged(req->bio, BIO_SEG_VALID)))
1468 blk_recount_segments(q, req->bio);
1469 if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(req->bio)) &&
1470 !BIOVEC_VIRT_OVERSIZE(len)) {
1471 int mergeable = ll_new_mergeable(q, req, bio);
1472
1473 if (mergeable) {
1474 if (bio->bi_hw_segments == 1)
1475 bio->bi_hw_front_size = len;
1476 if (req->nr_hw_segments == 1)
1477 req->biotail->bi_hw_back_size = len;
1478 }
1479 return mergeable;
1480 }
1481
1482 return ll_new_hw_segment(q, req, bio);
1483}
1484
1485static int ll_merge_requests_fn(request_queue_t *q, struct request *req,
1486 struct request *next)
1487{
Nikita Danilovdfa1a552005-06-25 14:59:20 -07001488 int total_phys_segments;
1489 int total_hw_segments;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001490
1491 /*
1492 * First check if the either of the requests are re-queued
1493 * requests. Can't merge them if they are.
1494 */
1495 if (req->special || next->special)
1496 return 0;
1497
1498 /*
Nikita Danilovdfa1a552005-06-25 14:59:20 -07001499 * Will it become too large?
Linus Torvalds1da177e2005-04-16 15:20:36 -07001500 */
1501 if ((req->nr_sectors + next->nr_sectors) > q->max_sectors)
1502 return 0;
1503
1504 total_phys_segments = req->nr_phys_segments + next->nr_phys_segments;
1505 if (blk_phys_contig_segment(q, req->biotail, next->bio))
1506 total_phys_segments--;
1507
1508 if (total_phys_segments > q->max_phys_segments)
1509 return 0;
1510
1511 total_hw_segments = req->nr_hw_segments + next->nr_hw_segments;
1512 if (blk_hw_contig_segment(q, req->biotail, next->bio)) {
1513 int len = req->biotail->bi_hw_back_size + next->bio->bi_hw_front_size;
1514 /*
1515 * propagate the combined length to the end of the requests
1516 */
1517 if (req->nr_hw_segments == 1)
1518 req->bio->bi_hw_front_size = len;
1519 if (next->nr_hw_segments == 1)
1520 next->biotail->bi_hw_back_size = len;
1521 total_hw_segments--;
1522 }
1523
1524 if (total_hw_segments > q->max_hw_segments)
1525 return 0;
1526
1527 /* Merge is OK... */
1528 req->nr_phys_segments = total_phys_segments;
1529 req->nr_hw_segments = total_hw_segments;
1530 return 1;
1531}
1532
1533/*
1534 * "plug" the device if there are no outstanding requests: this will
1535 * force the transfer to start only after we have put all the requests
1536 * on the list.
1537 *
1538 * This is called with interrupts off and no requests on the queue and
1539 * with the queue lock held.
1540 */
1541void blk_plug_device(request_queue_t *q)
1542{
1543 WARN_ON(!irqs_disabled());
1544
1545 /*
1546 * don't plug a stopped queue, it must be paired with blk_start_queue()
1547 * which will restart the queueing
1548 */
Coywolf Qi Hunt7daac492006-04-19 10:14:49 +02001549 if (blk_queue_stopped(q))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001550 return;
1551
Jens Axboe2056a782006-03-23 20:00:26 +01001552 if (!test_and_set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001553 mod_timer(&q->unplug_timer, jiffies + q->unplug_delay);
Jens Axboe2056a782006-03-23 20:00:26 +01001554 blk_add_trace_generic(q, NULL, 0, BLK_TA_PLUG);
1555 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001556}
1557
1558EXPORT_SYMBOL(blk_plug_device);
1559
1560/*
1561 * remove the queue from the plugged list, if present. called with
1562 * queue lock held and interrupts disabled.
1563 */
1564int blk_remove_plug(request_queue_t *q)
1565{
1566 WARN_ON(!irqs_disabled());
1567
1568 if (!test_and_clear_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags))
1569 return 0;
1570
1571 del_timer(&q->unplug_timer);
1572 return 1;
1573}
1574
1575EXPORT_SYMBOL(blk_remove_plug);
1576
1577/*
1578 * remove the plug and let it rip..
1579 */
1580void __generic_unplug_device(request_queue_t *q)
1581{
Coywolf Qi Hunt7daac492006-04-19 10:14:49 +02001582 if (unlikely(blk_queue_stopped(q)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001583 return;
1584
1585 if (!blk_remove_plug(q))
1586 return;
1587
Jens Axboe22e2c502005-06-27 10:55:12 +02001588 q->request_fn(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001589}
1590EXPORT_SYMBOL(__generic_unplug_device);
1591
1592/**
1593 * generic_unplug_device - fire a request queue
1594 * @q: The &request_queue_t in question
1595 *
1596 * Description:
1597 * Linux uses plugging to build bigger requests queues before letting
1598 * the device have at them. If a queue is plugged, the I/O scheduler
1599 * is still adding and merging requests on the queue. Once the queue
1600 * gets unplugged, the request_fn defined for the queue is invoked and
1601 * transfers started.
1602 **/
1603void generic_unplug_device(request_queue_t *q)
1604{
1605 spin_lock_irq(q->queue_lock);
1606 __generic_unplug_device(q);
1607 spin_unlock_irq(q->queue_lock);
1608}
1609EXPORT_SYMBOL(generic_unplug_device);
1610
1611static void blk_backing_dev_unplug(struct backing_dev_info *bdi,
1612 struct page *page)
1613{
1614 request_queue_t *q = bdi->unplug_io_data;
1615
1616 /*
1617 * devices don't necessarily have an ->unplug_fn defined
1618 */
Jens Axboe2056a782006-03-23 20:00:26 +01001619 if (q->unplug_fn) {
1620 blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL,
1621 q->rq.count[READ] + q->rq.count[WRITE]);
1622
Linus Torvalds1da177e2005-04-16 15:20:36 -07001623 q->unplug_fn(q);
Jens Axboe2056a782006-03-23 20:00:26 +01001624 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001625}
1626
David Howells65f27f32006-11-22 14:55:48 +00001627static void blk_unplug_work(struct work_struct *work)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001628{
David Howells65f27f32006-11-22 14:55:48 +00001629 request_queue_t *q = container_of(work, request_queue_t, unplug_work);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001630
Jens Axboe2056a782006-03-23 20:00:26 +01001631 blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL,
1632 q->rq.count[READ] + q->rq.count[WRITE]);
1633
Linus Torvalds1da177e2005-04-16 15:20:36 -07001634 q->unplug_fn(q);
1635}
1636
1637static void blk_unplug_timeout(unsigned long data)
1638{
1639 request_queue_t *q = (request_queue_t *)data;
1640
Jens Axboe2056a782006-03-23 20:00:26 +01001641 blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_TIMER, NULL,
1642 q->rq.count[READ] + q->rq.count[WRITE]);
1643
Linus Torvalds1da177e2005-04-16 15:20:36 -07001644 kblockd_schedule_work(&q->unplug_work);
1645}
1646
1647/**
1648 * blk_start_queue - restart a previously stopped queue
1649 * @q: The &request_queue_t in question
1650 *
1651 * Description:
1652 * blk_start_queue() will clear the stop flag on the queue, and call
1653 * the request_fn for the queue if it was in a stopped state when
1654 * entered. Also see blk_stop_queue(). Queue lock must be held.
1655 **/
1656void blk_start_queue(request_queue_t *q)
1657{
Paolo 'Blaisorblade' Giarrussoa038e252006-06-05 12:09:01 +02001658 WARN_ON(!irqs_disabled());
1659
Linus Torvalds1da177e2005-04-16 15:20:36 -07001660 clear_bit(QUEUE_FLAG_STOPPED, &q->queue_flags);
1661
1662 /*
1663 * one level of recursion is ok and is much faster than kicking
1664 * the unplug handling
1665 */
1666 if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) {
1667 q->request_fn(q);
1668 clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags);
1669 } else {
1670 blk_plug_device(q);
1671 kblockd_schedule_work(&q->unplug_work);
1672 }
1673}
1674
1675EXPORT_SYMBOL(blk_start_queue);
1676
1677/**
1678 * blk_stop_queue - stop a queue
1679 * @q: The &request_queue_t in question
1680 *
1681 * Description:
1682 * The Linux block layer assumes that a block driver will consume all
1683 * entries on the request queue when the request_fn strategy is called.
1684 * Often this will not happen, because of hardware limitations (queue
1685 * depth settings). If a device driver gets a 'queue full' response,
1686 * or if it simply chooses not to queue more I/O at one point, it can
1687 * call this function to prevent the request_fn from being called until
1688 * the driver has signalled it's ready to go again. This happens by calling
1689 * blk_start_queue() to restart queue operations. Queue lock must be held.
1690 **/
1691void blk_stop_queue(request_queue_t *q)
1692{
1693 blk_remove_plug(q);
1694 set_bit(QUEUE_FLAG_STOPPED, &q->queue_flags);
1695}
1696EXPORT_SYMBOL(blk_stop_queue);
1697
1698/**
1699 * blk_sync_queue - cancel any pending callbacks on a queue
1700 * @q: the queue
1701 *
1702 * Description:
1703 * The block layer may perform asynchronous callback activity
1704 * on a queue, such as calling the unplug function after a timeout.
1705 * A block device may call blk_sync_queue to ensure that any
1706 * such activity is cancelled, thus allowing it to release resources
1707 * the the callbacks might use. The caller must already have made sure
1708 * that its ->make_request_fn will not re-add plugging prior to calling
1709 * this function.
1710 *
1711 */
1712void blk_sync_queue(struct request_queue *q)
1713{
1714 del_timer_sync(&q->unplug_timer);
1715 kblockd_flush();
1716}
1717EXPORT_SYMBOL(blk_sync_queue);
1718
1719/**
1720 * blk_run_queue - run a single device queue
1721 * @q: The queue to run
1722 */
1723void blk_run_queue(struct request_queue *q)
1724{
1725 unsigned long flags;
1726
1727 spin_lock_irqsave(q->queue_lock, flags);
1728 blk_remove_plug(q);
Jens Axboedac07ec2006-05-11 08:20:16 +02001729
1730 /*
1731 * Only recurse once to avoid overrunning the stack, let the unplug
1732 * handling reinvoke the handler shortly if we already got there.
1733 */
1734 if (!elv_queue_empty(q)) {
1735 if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) {
1736 q->request_fn(q);
1737 clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags);
1738 } else {
1739 blk_plug_device(q);
1740 kblockd_schedule_work(&q->unplug_work);
1741 }
1742 }
1743
Linus Torvalds1da177e2005-04-16 15:20:36 -07001744 spin_unlock_irqrestore(q->queue_lock, flags);
1745}
1746EXPORT_SYMBOL(blk_run_queue);
1747
1748/**
1749 * blk_cleanup_queue: - release a &request_queue_t when it is no longer needed
Martin Waitza5802902006-04-02 13:59:55 +02001750 * @kobj: the kobj belonging of the request queue to be released
Linus Torvalds1da177e2005-04-16 15:20:36 -07001751 *
1752 * Description:
1753 * blk_cleanup_queue is the pair to blk_init_queue() or
1754 * blk_queue_make_request(). It should be called when a request queue is
1755 * being released; typically when a block device is being de-registered.
1756 * Currently, its primary task it to free all the &struct request
1757 * structures that were allocated to the queue and the queue itself.
1758 *
1759 * Caveat:
1760 * Hopefully the low level driver will have finished any
1761 * outstanding requests first...
1762 **/
Al Viro483f4af2006-03-18 18:34:37 -05001763static void blk_release_queue(struct kobject *kobj)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001764{
Al Viro483f4af2006-03-18 18:34:37 -05001765 request_queue_t *q = container_of(kobj, struct request_queue, kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001766 struct request_list *rl = &q->rq;
1767
Linus Torvalds1da177e2005-04-16 15:20:36 -07001768 blk_sync_queue(q);
1769
1770 if (rl->rq_pool)
1771 mempool_destroy(rl->rq_pool);
1772
1773 if (q->queue_tags)
1774 __blk_queue_free_tags(q);
1775
Alexey Dobriyan6c5c9342006-09-29 01:59:40 -07001776 blk_trace_shutdown(q);
Jens Axboe2056a782006-03-23 20:00:26 +01001777
Linus Torvalds1da177e2005-04-16 15:20:36 -07001778 kmem_cache_free(requestq_cachep, q);
1779}
1780
Al Viro483f4af2006-03-18 18:34:37 -05001781void blk_put_queue(request_queue_t *q)
1782{
1783 kobject_put(&q->kobj);
1784}
1785EXPORT_SYMBOL(blk_put_queue);
1786
1787void blk_cleanup_queue(request_queue_t * q)
1788{
1789 mutex_lock(&q->sysfs_lock);
1790 set_bit(QUEUE_FLAG_DEAD, &q->queue_flags);
1791 mutex_unlock(&q->sysfs_lock);
1792
1793 if (q->elevator)
1794 elevator_exit(q->elevator);
1795
1796 blk_put_queue(q);
1797}
1798
Linus Torvalds1da177e2005-04-16 15:20:36 -07001799EXPORT_SYMBOL(blk_cleanup_queue);
1800
1801static int blk_init_free_list(request_queue_t *q)
1802{
1803 struct request_list *rl = &q->rq;
1804
1805 rl->count[READ] = rl->count[WRITE] = 0;
1806 rl->starved[READ] = rl->starved[WRITE] = 0;
Tejun Heocb98fc82005-10-28 08:29:39 +02001807 rl->elvpriv = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001808 init_waitqueue_head(&rl->wait[READ]);
1809 init_waitqueue_head(&rl->wait[WRITE]);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001810
Christoph Lameter19460892005-06-23 00:08:19 -07001811 rl->rq_pool = mempool_create_node(BLKDEV_MIN_RQ, mempool_alloc_slab,
1812 mempool_free_slab, request_cachep, q->node);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001813
1814 if (!rl->rq_pool)
1815 return -ENOMEM;
1816
1817 return 0;
1818}
1819
Al Viro8267e262005-10-21 03:20:53 -04001820request_queue_t *blk_alloc_queue(gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001821{
Christoph Lameter19460892005-06-23 00:08:19 -07001822 return blk_alloc_queue_node(gfp_mask, -1);
1823}
1824EXPORT_SYMBOL(blk_alloc_queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001825
Al Viro483f4af2006-03-18 18:34:37 -05001826static struct kobj_type queue_ktype;
1827
Al Viro8267e262005-10-21 03:20:53 -04001828request_queue_t *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
Christoph Lameter19460892005-06-23 00:08:19 -07001829{
1830 request_queue_t *q;
1831
1832 q = kmem_cache_alloc_node(requestq_cachep, gfp_mask, node_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001833 if (!q)
1834 return NULL;
1835
1836 memset(q, 0, sizeof(*q));
1837 init_timer(&q->unplug_timer);
Al Viro483f4af2006-03-18 18:34:37 -05001838
1839 snprintf(q->kobj.name, KOBJ_NAME_LEN, "%s", "queue");
1840 q->kobj.ktype = &queue_ktype;
1841 kobject_init(&q->kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001842
1843 q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug;
1844 q->backing_dev_info.unplug_io_data = q;
1845
Al Viro483f4af2006-03-18 18:34:37 -05001846 mutex_init(&q->sysfs_lock);
1847
Linus Torvalds1da177e2005-04-16 15:20:36 -07001848 return q;
1849}
Christoph Lameter19460892005-06-23 00:08:19 -07001850EXPORT_SYMBOL(blk_alloc_queue_node);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001851
1852/**
1853 * blk_init_queue - prepare a request queue for use with a block device
1854 * @rfn: The function to be called to process requests that have been
1855 * placed on the queue.
1856 * @lock: Request queue spin lock
1857 *
1858 * Description:
1859 * If a block device wishes to use the standard request handling procedures,
1860 * which sorts requests and coalesces adjacent requests, then it must
1861 * call blk_init_queue(). The function @rfn will be called when there
1862 * are requests on the queue that need to be processed. If the device
1863 * supports plugging, then @rfn may not be called immediately when requests
1864 * are available on the queue, but may be called at some time later instead.
1865 * Plugged queues are generally unplugged when a buffer belonging to one
1866 * of the requests on the queue is needed, or due to memory pressure.
1867 *
1868 * @rfn is not required, or even expected, to remove all requests off the
1869 * queue, but only as many as it can handle at a time. If it does leave
1870 * requests on the queue, it is responsible for arranging that the requests
1871 * get dealt with eventually.
1872 *
1873 * The queue spin lock must be held while manipulating the requests on the
Paolo 'Blaisorblade' Giarrussoa038e252006-06-05 12:09:01 +02001874 * request queue; this lock will be taken also from interrupt context, so irq
1875 * disabling is needed for it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001876 *
1877 * Function returns a pointer to the initialized request queue, or NULL if
1878 * it didn't succeed.
1879 *
1880 * Note:
1881 * blk_init_queue() must be paired with a blk_cleanup_queue() call
1882 * when the block device is deactivated (such as at module unload).
1883 **/
Christoph Lameter19460892005-06-23 00:08:19 -07001884
Linus Torvalds1da177e2005-04-16 15:20:36 -07001885request_queue_t *blk_init_queue(request_fn_proc *rfn, spinlock_t *lock)
1886{
Christoph Lameter19460892005-06-23 00:08:19 -07001887 return blk_init_queue_node(rfn, lock, -1);
1888}
1889EXPORT_SYMBOL(blk_init_queue);
1890
1891request_queue_t *
1892blk_init_queue_node(request_fn_proc *rfn, spinlock_t *lock, int node_id)
1893{
1894 request_queue_t *q = blk_alloc_queue_node(GFP_KERNEL, node_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001895
1896 if (!q)
1897 return NULL;
1898
Christoph Lameter19460892005-06-23 00:08:19 -07001899 q->node = node_id;
Al Viro8669aaf2006-03-18 13:50:00 -05001900 if (blk_init_free_list(q)) {
1901 kmem_cache_free(requestq_cachep, q);
1902 return NULL;
1903 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001904
152587d2005-04-12 16:22:06 -05001905 /*
1906 * if caller didn't supply a lock, they get per-queue locking with
1907 * our embedded lock
1908 */
1909 if (!lock) {
1910 spin_lock_init(&q->__queue_lock);
1911 lock = &q->__queue_lock;
1912 }
1913
Linus Torvalds1da177e2005-04-16 15:20:36 -07001914 q->request_fn = rfn;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001915 q->prep_rq_fn = NULL;
1916 q->unplug_fn = generic_unplug_device;
1917 q->queue_flags = (1 << QUEUE_FLAG_CLUSTER);
1918 q->queue_lock = lock;
1919
1920 blk_queue_segment_boundary(q, 0xffffffff);
1921
1922 blk_queue_make_request(q, __make_request);
1923 blk_queue_max_segment_size(q, MAX_SEGMENT_SIZE);
1924
1925 blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS);
1926 blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS);
1927
1928 /*
1929 * all done
1930 */
1931 if (!elevator_init(q, NULL)) {
1932 blk_queue_congestion_threshold(q);
1933 return q;
1934 }
1935
Al Viro8669aaf2006-03-18 13:50:00 -05001936 blk_put_queue(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001937 return NULL;
1938}
Christoph Lameter19460892005-06-23 00:08:19 -07001939EXPORT_SYMBOL(blk_init_queue_node);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001940
1941int blk_get_queue(request_queue_t *q)
1942{
Nick Pigginfde6ad22005-06-23 00:08:53 -07001943 if (likely(!test_bit(QUEUE_FLAG_DEAD, &q->queue_flags))) {
Al Viro483f4af2006-03-18 18:34:37 -05001944 kobject_get(&q->kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001945 return 0;
1946 }
1947
1948 return 1;
1949}
1950
1951EXPORT_SYMBOL(blk_get_queue);
1952
1953static inline void blk_free_request(request_queue_t *q, struct request *rq)
1954{
Jens Axboe4aff5e22006-08-10 08:44:47 +02001955 if (rq->cmd_flags & REQ_ELVPRIV)
Tejun Heocb98fc82005-10-28 08:29:39 +02001956 elv_put_request(q, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001957 mempool_free(rq, q->rq.rq_pool);
1958}
1959
Jens Axboe1ea25ecb2006-07-18 22:24:11 +02001960static struct request *
Jens Axboecb78b282006-07-28 09:32:57 +02001961blk_alloc_request(request_queue_t *q, int rw, int priv, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001962{
1963 struct request *rq = mempool_alloc(q->rq.rq_pool, gfp_mask);
1964
1965 if (!rq)
1966 return NULL;
1967
1968 /*
Jens Axboe4aff5e22006-08-10 08:44:47 +02001969 * first three bits are identical in rq->cmd_flags and bio->bi_rw,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001970 * see bio.h and blkdev.h
1971 */
Jens Axboe49171e52006-08-10 08:59:11 +02001972 rq->cmd_flags = rw | REQ_ALLOCED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001973
Tejun Heocb98fc82005-10-28 08:29:39 +02001974 if (priv) {
Jens Axboecb78b282006-07-28 09:32:57 +02001975 if (unlikely(elv_set_request(q, rq, gfp_mask))) {
Tejun Heocb98fc82005-10-28 08:29:39 +02001976 mempool_free(rq, q->rq.rq_pool);
1977 return NULL;
1978 }
Jens Axboe4aff5e22006-08-10 08:44:47 +02001979 rq->cmd_flags |= REQ_ELVPRIV;
Tejun Heocb98fc82005-10-28 08:29:39 +02001980 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001981
Tejun Heocb98fc82005-10-28 08:29:39 +02001982 return rq;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001983}
1984
1985/*
1986 * ioc_batching returns true if the ioc is a valid batching request and
1987 * should be given priority access to a request.
1988 */
1989static inline int ioc_batching(request_queue_t *q, struct io_context *ioc)
1990{
1991 if (!ioc)
1992 return 0;
1993
1994 /*
1995 * Make sure the process is able to allocate at least 1 request
1996 * even if the batch times out, otherwise we could theoretically
1997 * lose wakeups.
1998 */
1999 return ioc->nr_batch_requests == q->nr_batching ||
2000 (ioc->nr_batch_requests > 0
2001 && time_before(jiffies, ioc->last_waited + BLK_BATCH_TIME));
2002}
2003
2004/*
2005 * ioc_set_batching sets ioc to be a new "batcher" if it is not one. This
2006 * will cause the process to be a "batcher" on all queues in the system. This
2007 * is the behaviour we want though - once it gets a wakeup it should be given
2008 * a nice run.
2009 */
Adrian Bunk93d17d32005-06-25 14:59:10 -07002010static void ioc_set_batching(request_queue_t *q, struct io_context *ioc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002011{
2012 if (!ioc || ioc_batching(q, ioc))
2013 return;
2014
2015 ioc->nr_batch_requests = q->nr_batching;
2016 ioc->last_waited = jiffies;
2017}
2018
2019static void __freed_request(request_queue_t *q, int rw)
2020{
2021 struct request_list *rl = &q->rq;
2022
2023 if (rl->count[rw] < queue_congestion_off_threshold(q))
Thomas Maier79e2de42006-10-19 23:28:15 -07002024 blk_clear_queue_congested(q, rw);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002025
2026 if (rl->count[rw] + 1 <= q->nr_requests) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002027 if (waitqueue_active(&rl->wait[rw]))
2028 wake_up(&rl->wait[rw]);
2029
2030 blk_clear_queue_full(q, rw);
2031 }
2032}
2033
2034/*
2035 * A request has just been released. Account for it, update the full and
2036 * congestion status, wake up any waiters. Called under q->queue_lock.
2037 */
Tejun Heocb98fc82005-10-28 08:29:39 +02002038static void freed_request(request_queue_t *q, int rw, int priv)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002039{
2040 struct request_list *rl = &q->rq;
2041
2042 rl->count[rw]--;
Tejun Heocb98fc82005-10-28 08:29:39 +02002043 if (priv)
2044 rl->elvpriv--;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002045
2046 __freed_request(q, rw);
2047
2048 if (unlikely(rl->starved[rw ^ 1]))
2049 __freed_request(q, rw ^ 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002050}
2051
2052#define blkdev_free_rq(list) list_entry((list)->next, struct request, queuelist)
2053/*
Nick Piggind6344532005-06-28 20:45:14 -07002054 * Get a free request, queue_lock must be held.
2055 * Returns NULL on failure, with queue_lock held.
2056 * Returns !NULL on success, with queue_lock *not held*.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002057 */
Jens Axboe7749a8d2006-12-13 13:02:26 +01002058static struct request *get_request(request_queue_t *q, int rw_flags,
2059 struct bio *bio, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002060{
2061 struct request *rq = NULL;
2062 struct request_list *rl = &q->rq;
Jens Axboe88ee5ef2005-11-12 11:09:12 +01002063 struct io_context *ioc = NULL;
Jens Axboe7749a8d2006-12-13 13:02:26 +01002064 const int rw = rw_flags & 0x01;
Jens Axboe88ee5ef2005-11-12 11:09:12 +01002065 int may_queue, priv;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002066
Jens Axboe7749a8d2006-12-13 13:02:26 +01002067 may_queue = elv_may_queue(q, rw_flags);
Jens Axboe88ee5ef2005-11-12 11:09:12 +01002068 if (may_queue == ELV_MQUEUE_NO)
2069 goto rq_starved;
2070
2071 if (rl->count[rw]+1 >= queue_congestion_on_threshold(q)) {
2072 if (rl->count[rw]+1 >= q->nr_requests) {
Jens Axboeb5deef92006-07-19 23:39:40 +02002073 ioc = current_io_context(GFP_ATOMIC, q->node);
Jens Axboe88ee5ef2005-11-12 11:09:12 +01002074 /*
2075 * The queue will fill after this allocation, so set
2076 * it as full, and mark this process as "batching".
2077 * This process will be allowed to complete a batch of
2078 * requests, others will be blocked.
2079 */
2080 if (!blk_queue_full(q, rw)) {
2081 ioc_set_batching(q, ioc);
2082 blk_set_queue_full(q, rw);
2083 } else {
2084 if (may_queue != ELV_MQUEUE_MUST
2085 && !ioc_batching(q, ioc)) {
2086 /*
2087 * The queue is full and the allocating
2088 * process is not a "batcher", and not
2089 * exempted by the IO scheduler
2090 */
2091 goto out;
2092 }
2093 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002094 }
Thomas Maier79e2de42006-10-19 23:28:15 -07002095 blk_set_queue_congested(q, rw);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002096 }
2097
Jens Axboe082cf692005-06-28 16:35:11 +02002098 /*
2099 * Only allow batching queuers to allocate up to 50% over the defined
2100 * limit of requests, otherwise we could have thousands of requests
2101 * allocated with any setting of ->nr_requests
2102 */
Hugh Dickinsfd782a42005-06-29 15:15:40 +01002103 if (rl->count[rw] >= (3 * q->nr_requests / 2))
Jens Axboe082cf692005-06-28 16:35:11 +02002104 goto out;
Hugh Dickinsfd782a42005-06-29 15:15:40 +01002105
Linus Torvalds1da177e2005-04-16 15:20:36 -07002106 rl->count[rw]++;
2107 rl->starved[rw] = 0;
Tejun Heocb98fc82005-10-28 08:29:39 +02002108
Jens Axboe64521d12005-10-28 08:30:39 +02002109 priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
Tejun Heocb98fc82005-10-28 08:29:39 +02002110 if (priv)
2111 rl->elvpriv++;
2112
Linus Torvalds1da177e2005-04-16 15:20:36 -07002113 spin_unlock_irq(q->queue_lock);
2114
Jens Axboe7749a8d2006-12-13 13:02:26 +01002115 rq = blk_alloc_request(q, rw_flags, priv, gfp_mask);
Jens Axboe88ee5ef2005-11-12 11:09:12 +01002116 if (unlikely(!rq)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002117 /*
2118 * Allocation failed presumably due to memory. Undo anything
2119 * we might have messed up.
2120 *
2121 * Allocating task should really be put onto the front of the
2122 * wait queue, but this is pretty rare.
2123 */
2124 spin_lock_irq(q->queue_lock);
Tejun Heocb98fc82005-10-28 08:29:39 +02002125 freed_request(q, rw, priv);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002126
2127 /*
2128 * in the very unlikely event that allocation failed and no
2129 * requests for this direction was pending, mark us starved
2130 * so that freeing of a request in the other direction will
2131 * notice us. another possible fix would be to split the
2132 * rq mempool into READ and WRITE
2133 */
2134rq_starved:
2135 if (unlikely(rl->count[rw] == 0))
2136 rl->starved[rw] = 1;
2137
Linus Torvalds1da177e2005-04-16 15:20:36 -07002138 goto out;
2139 }
2140
Jens Axboe88ee5ef2005-11-12 11:09:12 +01002141 /*
2142 * ioc may be NULL here, and ioc_batching will be false. That's
2143 * OK, if the queue is under the request limit then requests need
2144 * not count toward the nr_batch_requests limit. There will always
2145 * be some limit enforced by BLK_BATCH_TIME.
2146 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002147 if (ioc_batching(q, ioc))
2148 ioc->nr_batch_requests--;
2149
2150 rq_init(q, rq);
Jens Axboe2056a782006-03-23 20:00:26 +01002151
2152 blk_add_trace_generic(q, bio, rw, BLK_TA_GETRQ);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002153out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002154 return rq;
2155}
2156
2157/*
2158 * No available requests for this queue, unplug the device and wait for some
2159 * requests to become available.
Nick Piggind6344532005-06-28 20:45:14 -07002160 *
2161 * Called with q->queue_lock held, and returns with it unlocked.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002162 */
Jens Axboe7749a8d2006-12-13 13:02:26 +01002163static struct request *get_request_wait(request_queue_t *q, int rw_flags,
Jens Axboe22e2c502005-06-27 10:55:12 +02002164 struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002165{
Jens Axboe7749a8d2006-12-13 13:02:26 +01002166 const int rw = rw_flags & 0x01;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002167 struct request *rq;
2168
Jens Axboe7749a8d2006-12-13 13:02:26 +01002169 rq = get_request(q, rw_flags, bio, GFP_NOIO);
Nick Piggin450991b2005-06-28 20:45:13 -07002170 while (!rq) {
2171 DEFINE_WAIT(wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002172 struct request_list *rl = &q->rq;
2173
2174 prepare_to_wait_exclusive(&rl->wait[rw], &wait,
2175 TASK_UNINTERRUPTIBLE);
2176
Jens Axboe7749a8d2006-12-13 13:02:26 +01002177 rq = get_request(q, rw_flags, bio, GFP_NOIO);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002178
2179 if (!rq) {
2180 struct io_context *ioc;
2181
Jens Axboe2056a782006-03-23 20:00:26 +01002182 blk_add_trace_generic(q, bio, rw, BLK_TA_SLEEPRQ);
2183
Nick Piggind6344532005-06-28 20:45:14 -07002184 __generic_unplug_device(q);
2185 spin_unlock_irq(q->queue_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002186 io_schedule();
2187
2188 /*
2189 * After sleeping, we become a "batching" process and
2190 * will be able to allocate at least one request, and
2191 * up to a big batch of them for a small period time.
2192 * See ioc_batching, ioc_set_batching
2193 */
Jens Axboeb5deef92006-07-19 23:39:40 +02002194 ioc = current_io_context(GFP_NOIO, q->node);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002195 ioc_set_batching(q, ioc);
Nick Piggind6344532005-06-28 20:45:14 -07002196
2197 spin_lock_irq(q->queue_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002198 }
2199 finish_wait(&rl->wait[rw], &wait);
Nick Piggin450991b2005-06-28 20:45:13 -07002200 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002201
2202 return rq;
2203}
2204
Al Viro8267e262005-10-21 03:20:53 -04002205struct request *blk_get_request(request_queue_t *q, int rw, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002206{
2207 struct request *rq;
2208
2209 BUG_ON(rw != READ && rw != WRITE);
2210
Nick Piggind6344532005-06-28 20:45:14 -07002211 spin_lock_irq(q->queue_lock);
2212 if (gfp_mask & __GFP_WAIT) {
Jens Axboe22e2c502005-06-27 10:55:12 +02002213 rq = get_request_wait(q, rw, NULL);
Nick Piggind6344532005-06-28 20:45:14 -07002214 } else {
Jens Axboe22e2c502005-06-27 10:55:12 +02002215 rq = get_request(q, rw, NULL, gfp_mask);
Nick Piggind6344532005-06-28 20:45:14 -07002216 if (!rq)
2217 spin_unlock_irq(q->queue_lock);
2218 }
2219 /* q->queue_lock is unlocked at this point */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002220
2221 return rq;
2222}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002223EXPORT_SYMBOL(blk_get_request);
2224
2225/**
Jens Axboedc72ef42006-07-20 14:54:05 +02002226 * blk_start_queueing - initiate dispatch of requests to device
2227 * @q: request queue to kick into gear
2228 *
2229 * This is basically a helper to remove the need to know whether a queue
2230 * is plugged or not if someone just wants to initiate dispatch of requests
2231 * for this queue.
2232 *
2233 * The queue lock must be held with interrupts disabled.
2234 */
2235void blk_start_queueing(request_queue_t *q)
2236{
2237 if (!blk_queue_plugged(q))
2238 q->request_fn(q);
2239 else
2240 __generic_unplug_device(q);
2241}
2242EXPORT_SYMBOL(blk_start_queueing);
2243
2244/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07002245 * blk_requeue_request - put a request back on queue
2246 * @q: request queue where request should be inserted
2247 * @rq: request to be inserted
2248 *
2249 * Description:
2250 * Drivers often keep queueing requests until the hardware cannot accept
2251 * more, when that condition happens we need to put the request back
2252 * on the queue. Must be called with queue lock held.
2253 */
2254void blk_requeue_request(request_queue_t *q, struct request *rq)
2255{
Jens Axboe2056a782006-03-23 20:00:26 +01002256 blk_add_trace_rq(q, rq, BLK_TA_REQUEUE);
2257
Linus Torvalds1da177e2005-04-16 15:20:36 -07002258 if (blk_rq_tagged(rq))
2259 blk_queue_end_tag(q, rq);
2260
2261 elv_requeue_request(q, rq);
2262}
2263
2264EXPORT_SYMBOL(blk_requeue_request);
2265
2266/**
2267 * blk_insert_request - insert a special request in to a request queue
2268 * @q: request queue where request should be inserted
2269 * @rq: request to be inserted
2270 * @at_head: insert request at head or tail of queue
2271 * @data: private data
Linus Torvalds1da177e2005-04-16 15:20:36 -07002272 *
2273 * Description:
2274 * Many block devices need to execute commands asynchronously, so they don't
2275 * block the whole kernel from preemption during request execution. This is
2276 * accomplished normally by inserting aritficial requests tagged as
2277 * REQ_SPECIAL in to the corresponding request queue, and letting them be
2278 * scheduled for actual execution by the request queue.
2279 *
2280 * We have the option of inserting the head or the tail of the queue.
2281 * Typically we use the tail for new ioctls and so forth. We use the head
2282 * of the queue for things like a QUEUE_FULL message from a device, or a
2283 * host that is unable to accept a particular command.
2284 */
2285void blk_insert_request(request_queue_t *q, struct request *rq,
Tejun Heo 867d1192005-04-24 02:06:05 -05002286 int at_head, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002287{
Tejun Heo 867d1192005-04-24 02:06:05 -05002288 int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002289 unsigned long flags;
2290
2291 /*
2292 * tell I/O scheduler that this isn't a regular read/write (ie it
2293 * must not attempt merges on this) and that it acts as a soft
2294 * barrier
2295 */
Jens Axboe4aff5e22006-08-10 08:44:47 +02002296 rq->cmd_type = REQ_TYPE_SPECIAL;
2297 rq->cmd_flags |= REQ_SOFTBARRIER;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002298
2299 rq->special = data;
2300
2301 spin_lock_irqsave(q->queue_lock, flags);
2302
2303 /*
2304 * If command is tagged, release the tag
2305 */
Tejun Heo 867d1192005-04-24 02:06:05 -05002306 if (blk_rq_tagged(rq))
2307 blk_queue_end_tag(q, rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002308
Tejun Heo 867d1192005-04-24 02:06:05 -05002309 drive_stat_acct(rq, rq->nr_sectors, 1);
2310 __elv_add_request(q, rq, where, 0);
Jens Axboedc72ef42006-07-20 14:54:05 +02002311 blk_start_queueing(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002312 spin_unlock_irqrestore(q->queue_lock, flags);
2313}
2314
2315EXPORT_SYMBOL(blk_insert_request);
2316
Mike Christie0e75f902006-12-01 10:40:55 +01002317static int __blk_rq_unmap_user(struct bio *bio)
2318{
2319 int ret = 0;
2320
2321 if (bio) {
2322 if (bio_flagged(bio, BIO_USER_MAPPED))
2323 bio_unmap_user(bio);
2324 else
2325 ret = bio_uncopy_user(bio);
2326 }
2327
2328 return ret;
2329}
2330
2331static int __blk_rq_map_user(request_queue_t *q, struct request *rq,
2332 void __user *ubuf, unsigned int len)
2333{
2334 unsigned long uaddr;
2335 struct bio *bio, *orig_bio;
2336 int reading, ret;
2337
2338 reading = rq_data_dir(rq) == READ;
2339
2340 /*
2341 * if alignment requirement is satisfied, map in user pages for
2342 * direct dma. else, set up kernel bounce buffers
2343 */
2344 uaddr = (unsigned long) ubuf;
2345 if (!(uaddr & queue_dma_alignment(q)) && !(len & queue_dma_alignment(q)))
2346 bio = bio_map_user(q, NULL, uaddr, len, reading);
2347 else
2348 bio = bio_copy_user(q, uaddr, len, reading);
2349
Jens Axboe29852592006-12-19 08:27:31 +01002350 if (IS_ERR(bio))
Mike Christie0e75f902006-12-01 10:40:55 +01002351 return PTR_ERR(bio);
Mike Christie0e75f902006-12-01 10:40:55 +01002352
2353 orig_bio = bio;
2354 blk_queue_bounce(q, &bio);
Jens Axboe29852592006-12-19 08:27:31 +01002355
Mike Christie0e75f902006-12-01 10:40:55 +01002356 /*
2357 * We link the bounce buffer in and could have to traverse it
2358 * later so we have to get a ref to prevent it from being freed
2359 */
2360 bio_get(bio);
2361
Mike Christie0e75f902006-12-01 10:40:55 +01002362 if (!rq->bio)
2363 blk_rq_bio_prep(q, rq, bio);
Jens Axboe1aa4f242006-12-19 08:33:11 +01002364 else if (!ll_back_merge_fn(q, rq, bio)) {
Mike Christie0e75f902006-12-01 10:40:55 +01002365 ret = -EINVAL;
Mike Christie0e75f902006-12-01 10:40:55 +01002366 goto unmap_bio;
2367 } else {
2368 rq->biotail->bi_next = bio;
2369 rq->biotail = bio;
2370
Mike Christie0e75f902006-12-01 10:40:55 +01002371 rq->data_len += bio->bi_size;
2372 }
Mike Christie0e75f902006-12-01 10:40:55 +01002373
2374 return bio->bi_size;
2375
2376unmap_bio:
2377 /* if it was boucned we must call the end io function */
2378 bio_endio(bio, bio->bi_size, 0);
2379 __blk_rq_unmap_user(orig_bio);
2380 bio_put(bio);
2381 return ret;
2382}
2383
Linus Torvalds1da177e2005-04-16 15:20:36 -07002384/**
2385 * blk_rq_map_user - map user data to a request, for REQ_BLOCK_PC usage
2386 * @q: request queue where request should be inserted
Christoph Hellwig 73747ae2005-06-20 14:21:01 +02002387 * @rq: request structure to fill
Linus Torvalds1da177e2005-04-16 15:20:36 -07002388 * @ubuf: the user buffer
2389 * @len: length of user data
2390 *
2391 * Description:
2392 * Data will be mapped directly for zero copy io, if possible. Otherwise
2393 * a kernel bounce buffer is used.
2394 *
2395 * A matching blk_rq_unmap_user() must be issued at the end of io, while
2396 * still in process context.
2397 *
2398 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
2399 * before being submitted to the device, as pages mapped may be out of
2400 * reach. It's the callers responsibility to make sure this happens. The
2401 * original bio must be passed back in to blk_rq_unmap_user() for proper
2402 * unmapping.
2403 */
Jens Axboedd1cab92005-06-20 14:06:01 +02002404int blk_rq_map_user(request_queue_t *q, struct request *rq, void __user *ubuf,
Mike Christie0e75f902006-12-01 10:40:55 +01002405 unsigned long len)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002406{
Mike Christie0e75f902006-12-01 10:40:55 +01002407 unsigned long bytes_read = 0;
Jens Axboe8e5cfc42006-12-19 11:12:46 +01002408 struct bio *bio = NULL;
Mike Christie0e75f902006-12-01 10:40:55 +01002409 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002410
Mike Christiedefd94b2005-12-05 02:37:06 -06002411 if (len > (q->max_hw_sectors << 9))
Jens Axboedd1cab92005-06-20 14:06:01 +02002412 return -EINVAL;
2413 if (!len || !ubuf)
2414 return -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002415
Mike Christie0e75f902006-12-01 10:40:55 +01002416 while (bytes_read != len) {
2417 unsigned long map_len, end, start;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002418
Mike Christie0e75f902006-12-01 10:40:55 +01002419 map_len = min_t(unsigned long, len - bytes_read, BIO_MAX_SIZE);
2420 end = ((unsigned long)ubuf + map_len + PAGE_SIZE - 1)
2421 >> PAGE_SHIFT;
2422 start = (unsigned long)ubuf >> PAGE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002423
Mike Christie0e75f902006-12-01 10:40:55 +01002424 /*
2425 * A bad offset could cause us to require BIO_MAX_PAGES + 1
2426 * pages. If this happens we just lower the requested
2427 * mapping len by a page so that we can fit
2428 */
2429 if (end - start > BIO_MAX_PAGES)
2430 map_len -= PAGE_SIZE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002431
Mike Christie0e75f902006-12-01 10:40:55 +01002432 ret = __blk_rq_map_user(q, rq, ubuf, map_len);
2433 if (ret < 0)
2434 goto unmap_rq;
Jens Axboe8e5cfc42006-12-19 11:12:46 +01002435 if (!bio)
2436 bio = rq->bio;
Mike Christie0e75f902006-12-01 10:40:55 +01002437 bytes_read += ret;
2438 ubuf += ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002439 }
2440
Mike Christie0e75f902006-12-01 10:40:55 +01002441 rq->buffer = rq->data = NULL;
2442 return 0;
2443unmap_rq:
Jens Axboe8e5cfc42006-12-19 11:12:46 +01002444 blk_rq_unmap_user(bio);
Mike Christie0e75f902006-12-01 10:40:55 +01002445 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002446}
2447
2448EXPORT_SYMBOL(blk_rq_map_user);
2449
2450/**
James Bottomley f1970ba2005-06-20 14:06:52 +02002451 * blk_rq_map_user_iov - map user data to a request, for REQ_BLOCK_PC usage
2452 * @q: request queue where request should be inserted
2453 * @rq: request to map data to
2454 * @iov: pointer to the iovec
2455 * @iov_count: number of elements in the iovec
Randy Dunlapaf9997e2006-12-22 01:06:52 -08002456 * @len: I/O byte count
James Bottomley f1970ba2005-06-20 14:06:52 +02002457 *
2458 * Description:
2459 * Data will be mapped directly for zero copy io, if possible. Otherwise
2460 * a kernel bounce buffer is used.
2461 *
2462 * A matching blk_rq_unmap_user() must be issued at the end of io, while
2463 * still in process context.
2464 *
2465 * Note: The mapped bio may need to be bounced through blk_queue_bounce()
2466 * before being submitted to the device, as pages mapped may be out of
2467 * reach. It's the callers responsibility to make sure this happens. The
2468 * original bio must be passed back in to blk_rq_unmap_user() for proper
2469 * unmapping.
2470 */
2471int blk_rq_map_user_iov(request_queue_t *q, struct request *rq,
Mike Christie0e75f902006-12-01 10:40:55 +01002472 struct sg_iovec *iov, int iov_count, unsigned int len)
James Bottomley f1970ba2005-06-20 14:06:52 +02002473{
2474 struct bio *bio;
2475
2476 if (!iov || iov_count <= 0)
2477 return -EINVAL;
2478
2479 /* we don't allow misaligned data like bio_map_user() does. If the
2480 * user is using sg, they're expected to know the alignment constraints
2481 * and respect them accordingly */
2482 bio = bio_map_user_iov(q, NULL, iov, iov_count, rq_data_dir(rq)== READ);
2483 if (IS_ERR(bio))
2484 return PTR_ERR(bio);
2485
Mike Christie0e75f902006-12-01 10:40:55 +01002486 if (bio->bi_size != len) {
2487 bio_endio(bio, bio->bi_size, 0);
2488 bio_unmap_user(bio);
2489 return -EINVAL;
2490 }
2491
2492 bio_get(bio);
James Bottomley f1970ba2005-06-20 14:06:52 +02002493 blk_rq_bio_prep(q, rq, bio);
2494 rq->buffer = rq->data = NULL;
James Bottomley f1970ba2005-06-20 14:06:52 +02002495 return 0;
2496}
2497
2498EXPORT_SYMBOL(blk_rq_map_user_iov);
2499
2500/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07002501 * blk_rq_unmap_user - unmap a request with user data
Jens Axboe8e5cfc42006-12-19 11:12:46 +01002502 * @bio: start of bio list
Linus Torvalds1da177e2005-04-16 15:20:36 -07002503 *
2504 * Description:
Jens Axboe8e5cfc42006-12-19 11:12:46 +01002505 * Unmap a rq previously mapped by blk_rq_map_user(). The caller must
2506 * supply the original rq->bio from the blk_rq_map_user() return, since
2507 * the io completion may have changed rq->bio.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002508 */
Jens Axboe8e5cfc42006-12-19 11:12:46 +01002509int blk_rq_unmap_user(struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002510{
Jens Axboe8e5cfc42006-12-19 11:12:46 +01002511 struct bio *mapped_bio;
Jens Axboe48785bb2006-12-19 11:07:59 +01002512 int ret = 0, ret2;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002513
Jens Axboe8e5cfc42006-12-19 11:12:46 +01002514 while (bio) {
2515 mapped_bio = bio;
2516 if (unlikely(bio_flagged(bio, BIO_BOUNCED)))
Mike Christie0e75f902006-12-01 10:40:55 +01002517 mapped_bio = bio->bi_private;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002518
Jens Axboe48785bb2006-12-19 11:07:59 +01002519 ret2 = __blk_rq_unmap_user(mapped_bio);
2520 if (ret2 && !ret)
2521 ret = ret2;
2522
Jens Axboe8e5cfc42006-12-19 11:12:46 +01002523 mapped_bio = bio;
2524 bio = bio->bi_next;
2525 bio_put(mapped_bio);
Mike Christie0e75f902006-12-01 10:40:55 +01002526 }
Jens Axboe48785bb2006-12-19 11:07:59 +01002527
2528 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002529}
2530
2531EXPORT_SYMBOL(blk_rq_unmap_user);
2532
2533/**
Mike Christie df46b9a2005-06-20 14:04:44 +02002534 * blk_rq_map_kern - map kernel data to a request, for REQ_BLOCK_PC usage
2535 * @q: request queue where request should be inserted
Christoph Hellwig 73747ae2005-06-20 14:21:01 +02002536 * @rq: request to fill
Mike Christie df46b9a2005-06-20 14:04:44 +02002537 * @kbuf: the kernel buffer
2538 * @len: length of user data
Christoph Hellwig 73747ae2005-06-20 14:21:01 +02002539 * @gfp_mask: memory allocation flags
Mike Christie df46b9a2005-06-20 14:04:44 +02002540 */
Jens Axboedd1cab92005-06-20 14:06:01 +02002541int blk_rq_map_kern(request_queue_t *q, struct request *rq, void *kbuf,
Al Viro8267e262005-10-21 03:20:53 -04002542 unsigned int len, gfp_t gfp_mask)
Mike Christie df46b9a2005-06-20 14:04:44 +02002543{
Mike Christie df46b9a2005-06-20 14:04:44 +02002544 struct bio *bio;
2545
Mike Christiedefd94b2005-12-05 02:37:06 -06002546 if (len > (q->max_hw_sectors << 9))
Jens Axboedd1cab92005-06-20 14:06:01 +02002547 return -EINVAL;
2548 if (!len || !kbuf)
2549 return -EINVAL;
Mike Christie df46b9a2005-06-20 14:04:44 +02002550
2551 bio = bio_map_kern(q, kbuf, len, gfp_mask);
Jens Axboedd1cab92005-06-20 14:06:01 +02002552 if (IS_ERR(bio))
2553 return PTR_ERR(bio);
Mike Christie df46b9a2005-06-20 14:04:44 +02002554
Jens Axboedd1cab92005-06-20 14:06:01 +02002555 if (rq_data_dir(rq) == WRITE)
2556 bio->bi_rw |= (1 << BIO_RW);
Mike Christie df46b9a2005-06-20 14:04:44 +02002557
Jens Axboedd1cab92005-06-20 14:06:01 +02002558 blk_rq_bio_prep(q, rq, bio);
Jens Axboedd1cab92005-06-20 14:06:01 +02002559 rq->buffer = rq->data = NULL;
Jens Axboedd1cab92005-06-20 14:06:01 +02002560 return 0;
Mike Christie df46b9a2005-06-20 14:04:44 +02002561}
2562
2563EXPORT_SYMBOL(blk_rq_map_kern);
2564
Christoph Hellwig 73747ae2005-06-20 14:21:01 +02002565/**
2566 * blk_execute_rq_nowait - insert a request into queue for execution
2567 * @q: queue to insert the request in
2568 * @bd_disk: matching gendisk
2569 * @rq: request to insert
2570 * @at_head: insert request at head or tail of queue
2571 * @done: I/O completion handler
2572 *
2573 * Description:
2574 * Insert a fully prepared request at the back of the io scheduler queue
2575 * for execution. Don't wait for completion.
2576 */
James Bottomley f1970ba2005-06-20 14:06:52 +02002577void blk_execute_rq_nowait(request_queue_t *q, struct gendisk *bd_disk,
2578 struct request *rq, int at_head,
Tejun Heo8ffdc652006-01-06 09:49:03 +01002579 rq_end_io_fn *done)
James Bottomley f1970ba2005-06-20 14:06:52 +02002580{
2581 int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
2582
2583 rq->rq_disk = bd_disk;
Jens Axboe4aff5e22006-08-10 08:44:47 +02002584 rq->cmd_flags |= REQ_NOMERGE;
James Bottomley f1970ba2005-06-20 14:06:52 +02002585 rq->end_io = done;
Andrew Morton4c5d0bb2006-03-22 08:08:01 +01002586 WARN_ON(irqs_disabled());
2587 spin_lock_irq(q->queue_lock);
2588 __elv_add_request(q, rq, where, 1);
2589 __generic_unplug_device(q);
2590 spin_unlock_irq(q->queue_lock);
James Bottomley f1970ba2005-06-20 14:06:52 +02002591}
Mike Christie6e39b69e2005-11-11 05:30:24 -06002592EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
2593
Linus Torvalds1da177e2005-04-16 15:20:36 -07002594/**
2595 * blk_execute_rq - insert a request into queue for execution
2596 * @q: queue to insert the request in
2597 * @bd_disk: matching gendisk
2598 * @rq: request to insert
James Bottomley 994ca9a2005-06-20 14:11:09 +02002599 * @at_head: insert request at head or tail of queue
Linus Torvalds1da177e2005-04-16 15:20:36 -07002600 *
2601 * Description:
2602 * Insert a fully prepared request at the back of the io scheduler queue
Christoph Hellwig 73747ae2005-06-20 14:21:01 +02002603 * for execution and wait for completion.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002604 */
2605int blk_execute_rq(request_queue_t *q, struct gendisk *bd_disk,
James Bottomley 994ca9a2005-06-20 14:11:09 +02002606 struct request *rq, int at_head)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002607{
Ingo Molnar60be6b92006-07-03 00:25:26 -07002608 DECLARE_COMPLETION_ONSTACK(wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002609 char sense[SCSI_SENSE_BUFFERSIZE];
2610 int err = 0;
2611
Linus Torvalds1da177e2005-04-16 15:20:36 -07002612 /*
2613 * we need an extra reference to the request, so we can look at
2614 * it after io completion
2615 */
2616 rq->ref_count++;
2617
2618 if (!rq->sense) {
2619 memset(sense, 0, sizeof(sense));
2620 rq->sense = sense;
2621 rq->sense_len = 0;
2622 }
2623
Jens Axboec00895a2006-09-30 20:29:12 +02002624 rq->end_io_data = &wait;
James Bottomley 994ca9a2005-06-20 14:11:09 +02002625 blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002626 wait_for_completion(&wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002627
2628 if (rq->errors)
2629 err = -EIO;
2630
2631 return err;
2632}
2633
2634EXPORT_SYMBOL(blk_execute_rq);
2635
2636/**
2637 * blkdev_issue_flush - queue a flush
2638 * @bdev: blockdev to issue flush for
2639 * @error_sector: error sector
2640 *
2641 * Description:
2642 * Issue a flush for the block device in question. Caller can supply
2643 * room for storing the error offset in case of a flush error, if they
2644 * wish to. Caller must run wait_for_completion() on its own.
2645 */
2646int blkdev_issue_flush(struct block_device *bdev, sector_t *error_sector)
2647{
2648 request_queue_t *q;
2649
2650 if (bdev->bd_disk == NULL)
2651 return -ENXIO;
2652
2653 q = bdev_get_queue(bdev);
2654 if (!q)
2655 return -ENXIO;
2656 if (!q->issue_flush_fn)
2657 return -EOPNOTSUPP;
2658
2659 return q->issue_flush_fn(q, bdev->bd_disk, error_sector);
2660}
2661
2662EXPORT_SYMBOL(blkdev_issue_flush);
2663
Adrian Bunk93d17d32005-06-25 14:59:10 -07002664static void drive_stat_acct(struct request *rq, int nr_sectors, int new_io)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002665{
2666 int rw = rq_data_dir(rq);
2667
2668 if (!blk_fs_request(rq) || !rq->rq_disk)
2669 return;
2670
Jens Axboed72d9042005-11-01 08:35:42 +01002671 if (!new_io) {
Jens Axboea3623572005-11-01 09:26:16 +01002672 __disk_stat_inc(rq->rq_disk, merges[rw]);
Jens Axboed72d9042005-11-01 08:35:42 +01002673 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002674 disk_round_stats(rq->rq_disk);
2675 rq->rq_disk->in_flight++;
2676 }
2677}
2678
2679/*
2680 * add-request adds a request to the linked list.
2681 * queue lock is held and interrupts disabled, as we muck with the
2682 * request queue list.
2683 */
2684static inline void add_request(request_queue_t * q, struct request * req)
2685{
2686 drive_stat_acct(req, req->nr_sectors, 1);
2687
Linus Torvalds1da177e2005-04-16 15:20:36 -07002688 /*
2689 * elevator indicated where it wants this request to be
2690 * inserted at elevator_merge time
2691 */
2692 __elv_add_request(q, req, ELEVATOR_INSERT_SORT, 0);
2693}
2694
2695/*
2696 * disk_round_stats() - Round off the performance stats on a struct
2697 * disk_stats.
2698 *
2699 * The average IO queue length and utilisation statistics are maintained
2700 * by observing the current state of the queue length and the amount of
2701 * time it has been in this state for.
2702 *
2703 * Normally, that accounting is done on IO completion, but that can result
2704 * in more than a second's worth of IO being accounted for within any one
2705 * second, leading to >100% utilisation. To deal with that, we call this
2706 * function to do a round-off before returning the results when reading
2707 * /proc/diskstats. This accounts immediately for all queue usage up to
2708 * the current jiffies and restarts the counters again.
2709 */
2710void disk_round_stats(struct gendisk *disk)
2711{
2712 unsigned long now = jiffies;
2713
Chen, Kenneth Wb2982642005-10-13 21:49:29 +02002714 if (now == disk->stamp)
2715 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002716
Chen, Kenneth W20e5c812005-10-13 21:48:42 +02002717 if (disk->in_flight) {
2718 __disk_stat_add(disk, time_in_queue,
2719 disk->in_flight * (now - disk->stamp));
2720 __disk_stat_add(disk, io_ticks, (now - disk->stamp));
2721 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002722 disk->stamp = now;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002723}
2724
Jun'ichi "Nick" Nomura3eaf8402006-02-01 03:04:53 -08002725EXPORT_SYMBOL_GPL(disk_round_stats);
2726
Linus Torvalds1da177e2005-04-16 15:20:36 -07002727/*
2728 * queue lock must be held
2729 */
Mike Christie6e39b69e2005-11-11 05:30:24 -06002730void __blk_put_request(request_queue_t *q, struct request *req)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002731{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002732 if (unlikely(!q))
2733 return;
2734 if (unlikely(--req->ref_count))
2735 return;
2736
Tejun Heo8922e162005-10-20 16:23:44 +02002737 elv_completed_request(q, req);
2738
Linus Torvalds1da177e2005-04-16 15:20:36 -07002739 /*
2740 * Request may not have originated from ll_rw_blk. if not,
2741 * it didn't come out of our reserved rq pools
2742 */
Jens Axboe49171e52006-08-10 08:59:11 +02002743 if (req->cmd_flags & REQ_ALLOCED) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002744 int rw = rq_data_dir(req);
Jens Axboe4aff5e22006-08-10 08:44:47 +02002745 int priv = req->cmd_flags & REQ_ELVPRIV;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002746
Linus Torvalds1da177e2005-04-16 15:20:36 -07002747 BUG_ON(!list_empty(&req->queuelist));
Jens Axboe98170642006-07-28 09:23:08 +02002748 BUG_ON(!hlist_unhashed(&req->hash));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002749
2750 blk_free_request(q, req);
Tejun Heocb98fc82005-10-28 08:29:39 +02002751 freed_request(q, rw, priv);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002752 }
2753}
2754
Mike Christie6e39b69e2005-11-11 05:30:24 -06002755EXPORT_SYMBOL_GPL(__blk_put_request);
2756
Linus Torvalds1da177e2005-04-16 15:20:36 -07002757void blk_put_request(struct request *req)
2758{
Tejun Heo8922e162005-10-20 16:23:44 +02002759 unsigned long flags;
2760 request_queue_t *q = req->q;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002761
Tejun Heo8922e162005-10-20 16:23:44 +02002762 /*
2763 * Gee, IDE calls in w/ NULL q. Fix IDE and remove the
2764 * following if (q) test.
2765 */
2766 if (q) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002767 spin_lock_irqsave(q->queue_lock, flags);
2768 __blk_put_request(q, req);
2769 spin_unlock_irqrestore(q->queue_lock, flags);
2770 }
2771}
2772
2773EXPORT_SYMBOL(blk_put_request);
2774
2775/**
2776 * blk_end_sync_rq - executes a completion event on a request
2777 * @rq: request to complete
Jens Axboefddfdea2006-01-31 15:24:34 +01002778 * @error: end io status of the request
Linus Torvalds1da177e2005-04-16 15:20:36 -07002779 */
Tejun Heo8ffdc652006-01-06 09:49:03 +01002780void blk_end_sync_rq(struct request *rq, int error)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002781{
Jens Axboec00895a2006-09-30 20:29:12 +02002782 struct completion *waiting = rq->end_io_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002783
Jens Axboec00895a2006-09-30 20:29:12 +02002784 rq->end_io_data = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002785 __blk_put_request(rq->q, rq);
2786
2787 /*
2788 * complete last, if this is a stack request the process (and thus
2789 * the rq pointer) could be invalid right after this complete()
2790 */
2791 complete(waiting);
2792}
2793EXPORT_SYMBOL(blk_end_sync_rq);
2794
Linus Torvalds1da177e2005-04-16 15:20:36 -07002795/*
2796 * Has to be called with the request spinlock acquired
2797 */
2798static int attempt_merge(request_queue_t *q, struct request *req,
2799 struct request *next)
2800{
2801 if (!rq_mergeable(req) || !rq_mergeable(next))
2802 return 0;
2803
2804 /*
Andreas Mohrd6e05ed2006-06-26 18:35:02 +02002805 * not contiguous
Linus Torvalds1da177e2005-04-16 15:20:36 -07002806 */
2807 if (req->sector + req->nr_sectors != next->sector)
2808 return 0;
2809
2810 if (rq_data_dir(req) != rq_data_dir(next)
2811 || req->rq_disk != next->rq_disk
Jens Axboec00895a2006-09-30 20:29:12 +02002812 || next->special)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002813 return 0;
2814
2815 /*
2816 * If we are allowed to merge, then append bio list
2817 * from next to rq and release next. merge_requests_fn
2818 * will have updated segment counts, update sector
2819 * counts here.
2820 */
Jens Axboe1aa4f242006-12-19 08:33:11 +01002821 if (!ll_merge_requests_fn(q, req, next))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002822 return 0;
2823
2824 /*
2825 * At this point we have either done a back merge
2826 * or front merge. We need the smaller start_time of
2827 * the merged requests to be the current request
2828 * for accounting purposes.
2829 */
2830 if (time_after(req->start_time, next->start_time))
2831 req->start_time = next->start_time;
2832
2833 req->biotail->bi_next = next->bio;
2834 req->biotail = next->biotail;
2835
2836 req->nr_sectors = req->hard_nr_sectors += next->hard_nr_sectors;
2837
2838 elv_merge_requests(q, req, next);
2839
2840 if (req->rq_disk) {
2841 disk_round_stats(req->rq_disk);
2842 req->rq_disk->in_flight--;
2843 }
2844
Jens Axboe22e2c502005-06-27 10:55:12 +02002845 req->ioprio = ioprio_best(req->ioprio, next->ioprio);
2846
Linus Torvalds1da177e2005-04-16 15:20:36 -07002847 __blk_put_request(q, next);
2848 return 1;
2849}
2850
2851static inline int attempt_back_merge(request_queue_t *q, struct request *rq)
2852{
2853 struct request *next = elv_latter_request(q, rq);
2854
2855 if (next)
2856 return attempt_merge(q, rq, next);
2857
2858 return 0;
2859}
2860
2861static inline int attempt_front_merge(request_queue_t *q, struct request *rq)
2862{
2863 struct request *prev = elv_former_request(q, rq);
2864
2865 if (prev)
2866 return attempt_merge(q, prev, rq);
2867
2868 return 0;
2869}
2870
Tejun Heo52d9e672006-01-06 09:49:58 +01002871static void init_request_from_bio(struct request *req, struct bio *bio)
2872{
Jens Axboe4aff5e22006-08-10 08:44:47 +02002873 req->cmd_type = REQ_TYPE_FS;
Tejun Heo52d9e672006-01-06 09:49:58 +01002874
2875 /*
2876 * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST)
2877 */
2878 if (bio_rw_ahead(bio) || bio_failfast(bio))
Jens Axboe4aff5e22006-08-10 08:44:47 +02002879 req->cmd_flags |= REQ_FAILFAST;
Tejun Heo52d9e672006-01-06 09:49:58 +01002880
2881 /*
2882 * REQ_BARRIER implies no merging, but lets make it explicit
2883 */
2884 if (unlikely(bio_barrier(bio)))
Jens Axboe4aff5e22006-08-10 08:44:47 +02002885 req->cmd_flags |= (REQ_HARDBARRIER | REQ_NOMERGE);
Tejun Heo52d9e672006-01-06 09:49:58 +01002886
Jens Axboeb31dc662006-06-13 08:26:10 +02002887 if (bio_sync(bio))
Jens Axboe4aff5e22006-08-10 08:44:47 +02002888 req->cmd_flags |= REQ_RW_SYNC;
Jens Axboe5404bc72006-08-10 09:01:02 +02002889 if (bio_rw_meta(bio))
2890 req->cmd_flags |= REQ_RW_META;
Jens Axboeb31dc662006-06-13 08:26:10 +02002891
Tejun Heo52d9e672006-01-06 09:49:58 +01002892 req->errors = 0;
2893 req->hard_sector = req->sector = bio->bi_sector;
2894 req->hard_nr_sectors = req->nr_sectors = bio_sectors(bio);
2895 req->current_nr_sectors = req->hard_cur_sectors = bio_cur_sectors(bio);
2896 req->nr_phys_segments = bio_phys_segments(req->q, bio);
2897 req->nr_hw_segments = bio_hw_segments(req->q, bio);
2898 req->buffer = bio_data(bio); /* see ->buffer comment above */
Tejun Heo52d9e672006-01-06 09:49:58 +01002899 req->bio = req->biotail = bio;
2900 req->ioprio = bio_prio(bio);
2901 req->rq_disk = bio->bi_bdev->bd_disk;
2902 req->start_time = jiffies;
2903}
2904
Linus Torvalds1da177e2005-04-16 15:20:36 -07002905static int __make_request(request_queue_t *q, struct bio *bio)
2906{
Nick Piggin450991b2005-06-28 20:45:13 -07002907 struct request *req;
Jens Axboe51da90f2006-07-18 04:14:45 +02002908 int el_ret, nr_sectors, barrier, err;
2909 const unsigned short prio = bio_prio(bio);
2910 const int sync = bio_sync(bio);
Jens Axboe7749a8d2006-12-13 13:02:26 +01002911 int rw_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002912
Linus Torvalds1da177e2005-04-16 15:20:36 -07002913 nr_sectors = bio_sectors(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002914
2915 /*
2916 * low level driver can indicate that it wants pages above a
2917 * certain limit bounced to low memory (ie for highmem, or even
2918 * ISA dma in theory)
2919 */
2920 blk_queue_bounce(q, &bio);
2921
Linus Torvalds1da177e2005-04-16 15:20:36 -07002922 barrier = bio_barrier(bio);
Tejun Heo797e7db2006-01-06 09:51:03 +01002923 if (unlikely(barrier) && (q->next_ordered == QUEUE_ORDERED_NONE)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002924 err = -EOPNOTSUPP;
2925 goto end_io;
2926 }
2927
Linus Torvalds1da177e2005-04-16 15:20:36 -07002928 spin_lock_irq(q->queue_lock);
2929
Nick Piggin450991b2005-06-28 20:45:13 -07002930 if (unlikely(barrier) || elv_queue_empty(q))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002931 goto get_rq;
2932
2933 el_ret = elv_merge(q, &req, bio);
2934 switch (el_ret) {
2935 case ELEVATOR_BACK_MERGE:
2936 BUG_ON(!rq_mergeable(req));
2937
Jens Axboe1aa4f242006-12-19 08:33:11 +01002938 if (!ll_back_merge_fn(q, req, bio))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002939 break;
2940
Jens Axboe2056a782006-03-23 20:00:26 +01002941 blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE);
2942
Linus Torvalds1da177e2005-04-16 15:20:36 -07002943 req->biotail->bi_next = bio;
2944 req->biotail = bio;
2945 req->nr_sectors = req->hard_nr_sectors += nr_sectors;
Jens Axboe22e2c502005-06-27 10:55:12 +02002946 req->ioprio = ioprio_best(req->ioprio, prio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002947 drive_stat_acct(req, nr_sectors, 0);
2948 if (!attempt_back_merge(q, req))
Jens Axboe2e662b62006-07-13 11:55:04 +02002949 elv_merged_request(q, req, el_ret);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002950 goto out;
2951
2952 case ELEVATOR_FRONT_MERGE:
2953 BUG_ON(!rq_mergeable(req));
2954
Jens Axboe1aa4f242006-12-19 08:33:11 +01002955 if (!ll_front_merge_fn(q, req, bio))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002956 break;
2957
Jens Axboe2056a782006-03-23 20:00:26 +01002958 blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE);
2959
Linus Torvalds1da177e2005-04-16 15:20:36 -07002960 bio->bi_next = req->bio;
2961 req->bio = bio;
2962
2963 /*
2964 * may not be valid. if the low level driver said
2965 * it didn't need a bounce buffer then it better
2966 * not touch req->buffer either...
2967 */
2968 req->buffer = bio_data(bio);
Jens Axboe51da90f2006-07-18 04:14:45 +02002969 req->current_nr_sectors = bio_cur_sectors(bio);
2970 req->hard_cur_sectors = req->current_nr_sectors;
2971 req->sector = req->hard_sector = bio->bi_sector;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002972 req->nr_sectors = req->hard_nr_sectors += nr_sectors;
Jens Axboe22e2c502005-06-27 10:55:12 +02002973 req->ioprio = ioprio_best(req->ioprio, prio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002974 drive_stat_acct(req, nr_sectors, 0);
2975 if (!attempt_front_merge(q, req))
Jens Axboe2e662b62006-07-13 11:55:04 +02002976 elv_merged_request(q, req, el_ret);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002977 goto out;
2978
Nick Piggin450991b2005-06-28 20:45:13 -07002979 /* ELV_NO_MERGE: elevator says don't/can't merge. */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002980 default:
Nick Piggin450991b2005-06-28 20:45:13 -07002981 ;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002982 }
2983
Linus Torvalds1da177e2005-04-16 15:20:36 -07002984get_rq:
Nick Piggin450991b2005-06-28 20:45:13 -07002985 /*
Jens Axboe7749a8d2006-12-13 13:02:26 +01002986 * This sync check and mask will be re-done in init_request_from_bio(),
2987 * but we need to set it earlier to expose the sync flag to the
2988 * rq allocator and io schedulers.
2989 */
2990 rw_flags = bio_data_dir(bio);
2991 if (sync)
2992 rw_flags |= REQ_RW_SYNC;
2993
2994 /*
Nick Piggin450991b2005-06-28 20:45:13 -07002995 * Grab a free request. This is might sleep but can not fail.
Nick Piggind6344532005-06-28 20:45:14 -07002996 * Returns with the queue unlocked.
Nick Piggin450991b2005-06-28 20:45:13 -07002997 */
Jens Axboe7749a8d2006-12-13 13:02:26 +01002998 req = get_request_wait(q, rw_flags, bio);
Nick Piggind6344532005-06-28 20:45:14 -07002999
Nick Piggin450991b2005-06-28 20:45:13 -07003000 /*
3001 * After dropping the lock and possibly sleeping here, our request
3002 * may now be mergeable after it had proven unmergeable (above).
3003 * We don't worry about that case for efficiency. It won't happen
3004 * often, and the elevators are able to handle it.
3005 */
Tejun Heo52d9e672006-01-06 09:49:58 +01003006 init_request_from_bio(req, bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003007
Nick Piggin450991b2005-06-28 20:45:13 -07003008 spin_lock_irq(q->queue_lock);
3009 if (elv_queue_empty(q))
3010 blk_plug_device(q);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003011 add_request(q, req);
3012out:
Jens Axboe4a534f92005-04-16 15:25:40 -07003013 if (sync)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003014 __generic_unplug_device(q);
3015
3016 spin_unlock_irq(q->queue_lock);
3017 return 0;
3018
3019end_io:
3020 bio_endio(bio, nr_sectors << 9, err);
3021 return 0;
3022}
3023
3024/*
3025 * If bio->bi_dev is a partition, remap the location
3026 */
3027static inline void blk_partition_remap(struct bio *bio)
3028{
3029 struct block_device *bdev = bio->bi_bdev;
3030
3031 if (bdev != bdev->bd_contains) {
3032 struct hd_struct *p = bdev->bd_part;
Jens Axboea3623572005-11-01 09:26:16 +01003033 const int rw = bio_data_dir(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003034
Jens Axboea3623572005-11-01 09:26:16 +01003035 p->sectors[rw] += bio_sectors(bio);
3036 p->ios[rw]++;
3037
Linus Torvalds1da177e2005-04-16 15:20:36 -07003038 bio->bi_sector += p->start_sect;
3039 bio->bi_bdev = bdev->bd_contains;
3040 }
3041}
3042
Linus Torvalds1da177e2005-04-16 15:20:36 -07003043static void handle_bad_sector(struct bio *bio)
3044{
3045 char b[BDEVNAME_SIZE];
3046
3047 printk(KERN_INFO "attempt to access beyond end of device\n");
3048 printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n",
3049 bdevname(bio->bi_bdev, b),
3050 bio->bi_rw,
3051 (unsigned long long)bio->bi_sector + bio_sectors(bio),
3052 (long long)(bio->bi_bdev->bd_inode->i_size >> 9));
3053
3054 set_bit(BIO_EOF, &bio->bi_flags);
3055}
3056
Akinobu Mitac17bb492006-12-08 02:39:46 -08003057#ifdef CONFIG_FAIL_MAKE_REQUEST
3058
3059static DECLARE_FAULT_ATTR(fail_make_request);
3060
3061static int __init setup_fail_make_request(char *str)
3062{
3063 return setup_fault_attr(&fail_make_request, str);
3064}
3065__setup("fail_make_request=", setup_fail_make_request);
3066
3067static int should_fail_request(struct bio *bio)
3068{
3069 if ((bio->bi_bdev->bd_disk->flags & GENHD_FL_FAIL) ||
3070 (bio->bi_bdev->bd_part && bio->bi_bdev->bd_part->make_it_fail))
3071 return should_fail(&fail_make_request, bio->bi_size);
3072
3073 return 0;
3074}
3075
3076static int __init fail_make_request_debugfs(void)
3077{
3078 return init_fault_attr_dentries(&fail_make_request,
3079 "fail_make_request");
3080}
3081
3082late_initcall(fail_make_request_debugfs);
3083
3084#else /* CONFIG_FAIL_MAKE_REQUEST */
3085
3086static inline int should_fail_request(struct bio *bio)
3087{
3088 return 0;
3089}
3090
3091#endif /* CONFIG_FAIL_MAKE_REQUEST */
3092
Linus Torvalds1da177e2005-04-16 15:20:36 -07003093/**
3094 * generic_make_request: hand a buffer to its device driver for I/O
3095 * @bio: The bio describing the location in memory and on the device.
3096 *
3097 * generic_make_request() is used to make I/O requests of block
3098 * devices. It is passed a &struct bio, which describes the I/O that needs
3099 * to be done.
3100 *
3101 * generic_make_request() does not return any status. The
3102 * success/failure status of the request, along with notification of
3103 * completion, is delivered asynchronously through the bio->bi_end_io
3104 * function described (one day) else where.
3105 *
3106 * The caller of generic_make_request must make sure that bi_io_vec
3107 * are set to describe the memory buffer, and that bi_dev and bi_sector are
3108 * set to describe the device address, and the
3109 * bi_end_io and optionally bi_private are set to describe how
3110 * completion notification should be signaled.
3111 *
3112 * generic_make_request and the drivers it calls may use bi_next if this
3113 * bio happens to be merged with someone else, and may change bi_dev and
3114 * bi_sector for remaps as it sees fit. So the values of these fields
3115 * should NOT be depended on after the call to generic_make_request.
3116 */
3117void generic_make_request(struct bio *bio)
3118{
3119 request_queue_t *q;
3120 sector_t maxsector;
NeilBrown5ddfe962006-10-30 22:07:21 -08003121 sector_t old_sector;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003122 int ret, nr_sectors = bio_sectors(bio);
Jens Axboe2056a782006-03-23 20:00:26 +01003123 dev_t old_dev;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003124
3125 might_sleep();
3126 /* Test device or partition size, when known. */
3127 maxsector = bio->bi_bdev->bd_inode->i_size >> 9;
3128 if (maxsector) {
3129 sector_t sector = bio->bi_sector;
3130
3131 if (maxsector < nr_sectors || maxsector - nr_sectors < sector) {
3132 /*
3133 * This may well happen - the kernel calls bread()
3134 * without checking the size of the device, e.g., when
3135 * mounting a device.
3136 */
3137 handle_bad_sector(bio);
3138 goto end_io;
3139 }
3140 }
3141
3142 /*
3143 * Resolve the mapping until finished. (drivers are
3144 * still free to implement/resolve their own stacking
3145 * by explicitly returning 0)
3146 *
3147 * NOTE: we don't repeat the blk_size check for each new device.
3148 * Stacking drivers are expected to know what they are doing.
3149 */
NeilBrown5ddfe962006-10-30 22:07:21 -08003150 old_sector = -1;
Jens Axboe2056a782006-03-23 20:00:26 +01003151 old_dev = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003152 do {
3153 char b[BDEVNAME_SIZE];
3154
3155 q = bdev_get_queue(bio->bi_bdev);
3156 if (!q) {
3157 printk(KERN_ERR
3158 "generic_make_request: Trying to access "
3159 "nonexistent block-device %s (%Lu)\n",
3160 bdevname(bio->bi_bdev, b),
3161 (long long) bio->bi_sector);
3162end_io:
3163 bio_endio(bio, bio->bi_size, -EIO);
3164 break;
3165 }
3166
3167 if (unlikely(bio_sectors(bio) > q->max_hw_sectors)) {
3168 printk("bio too big device %s (%u > %u)\n",
3169 bdevname(bio->bi_bdev, b),
3170 bio_sectors(bio),
3171 q->max_hw_sectors);
3172 goto end_io;
3173 }
3174
Nick Pigginfde6ad22005-06-23 00:08:53 -07003175 if (unlikely(test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003176 goto end_io;
3177
Akinobu Mitac17bb492006-12-08 02:39:46 -08003178 if (should_fail_request(bio))
3179 goto end_io;
3180
Linus Torvalds1da177e2005-04-16 15:20:36 -07003181 /*
3182 * If this device has partitions, remap block n
3183 * of partition p to block n+start(p) of the disk.
3184 */
3185 blk_partition_remap(bio);
3186
NeilBrown5ddfe962006-10-30 22:07:21 -08003187 if (old_sector != -1)
Jens Axboe2056a782006-03-23 20:00:26 +01003188 blk_add_trace_remap(q, bio, old_dev, bio->bi_sector,
NeilBrown5ddfe962006-10-30 22:07:21 -08003189 old_sector);
Jens Axboe2056a782006-03-23 20:00:26 +01003190
3191 blk_add_trace_bio(q, bio, BLK_TA_QUEUE);
3192
NeilBrown5ddfe962006-10-30 22:07:21 -08003193 old_sector = bio->bi_sector;
Jens Axboe2056a782006-03-23 20:00:26 +01003194 old_dev = bio->bi_bdev->bd_dev;
3195
NeilBrown5ddfe962006-10-30 22:07:21 -08003196 maxsector = bio->bi_bdev->bd_inode->i_size >> 9;
3197 if (maxsector) {
3198 sector_t sector = bio->bi_sector;
3199
Andrew Mortondf66b852006-11-02 22:06:56 -08003200 if (maxsector < nr_sectors ||
3201 maxsector - nr_sectors < sector) {
NeilBrown5ddfe962006-10-30 22:07:21 -08003202 /*
Andrew Mortondf66b852006-11-02 22:06:56 -08003203 * This may well happen - partitions are not
3204 * checked to make sure they are within the size
3205 * of the whole device.
NeilBrown5ddfe962006-10-30 22:07:21 -08003206 */
3207 handle_bad_sector(bio);
3208 goto end_io;
3209 }
3210 }
3211
Linus Torvalds1da177e2005-04-16 15:20:36 -07003212 ret = q->make_request_fn(q, bio);
3213 } while (ret);
3214}
3215
3216EXPORT_SYMBOL(generic_make_request);
3217
3218/**
3219 * submit_bio: submit a bio to the block device layer for I/O
3220 * @rw: whether to %READ or %WRITE, or maybe to %READA (read ahead)
3221 * @bio: The &struct bio which describes the I/O
3222 *
3223 * submit_bio() is very similar in purpose to generic_make_request(), and
3224 * uses that function to do most of the work. Both are fairly rough
3225 * interfaces, @bio must be presetup and ready for I/O.
3226 *
3227 */
3228void submit_bio(int rw, struct bio *bio)
3229{
3230 int count = bio_sectors(bio);
3231
3232 BIO_BUG_ON(!bio->bi_size);
3233 BIO_BUG_ON(!bio->bi_io_vec);
Jens Axboe22e2c502005-06-27 10:55:12 +02003234 bio->bi_rw |= rw;
Andrew Mortonfaccbd4b2006-12-10 02:19:35 -08003235 if (rw & WRITE) {
Christoph Lameterf8891e52006-06-30 01:55:45 -07003236 count_vm_events(PGPGOUT, count);
Andrew Mortonfaccbd4b2006-12-10 02:19:35 -08003237 } else {
3238 task_io_account_read(bio->bi_size);
Christoph Lameterf8891e52006-06-30 01:55:45 -07003239 count_vm_events(PGPGIN, count);
Andrew Mortonfaccbd4b2006-12-10 02:19:35 -08003240 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07003241
3242 if (unlikely(block_dump)) {
3243 char b[BDEVNAME_SIZE];
3244 printk(KERN_DEBUG "%s(%d): %s block %Lu on %s\n",
3245 current->comm, current->pid,
3246 (rw & WRITE) ? "WRITE" : "READ",
3247 (unsigned long long)bio->bi_sector,
3248 bdevname(bio->bi_bdev,b));
3249 }
3250
3251 generic_make_request(bio);
3252}
3253
3254EXPORT_SYMBOL(submit_bio);
3255
Adrian Bunk93d17d32005-06-25 14:59:10 -07003256static void blk_recalc_rq_segments(struct request *rq)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003257{
3258 struct bio *bio, *prevbio = NULL;
3259 int nr_phys_segs, nr_hw_segs;
3260 unsigned int phys_size, hw_size;
3261 request_queue_t *q = rq->q;
3262
3263 if (!rq->bio)
3264 return;
3265
3266 phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0;
3267 rq_for_each_bio(bio, rq) {
3268 /* Force bio hw/phys segs to be recalculated. */
3269 bio->bi_flags &= ~(1 << BIO_SEG_VALID);
3270
3271 nr_phys_segs += bio_phys_segments(q, bio);
3272 nr_hw_segs += bio_hw_segments(q, bio);
3273 if (prevbio) {
3274 int pseg = phys_size + prevbio->bi_size + bio->bi_size;
3275 int hseg = hw_size + prevbio->bi_size + bio->bi_size;
3276
3277 if (blk_phys_contig_segment(q, prevbio, bio) &&
3278 pseg <= q->max_segment_size) {
3279 nr_phys_segs--;
3280 phys_size += prevbio->bi_size + bio->bi_size;
3281 } else
3282 phys_size = 0;
3283
3284 if (blk_hw_contig_segment(q, prevbio, bio) &&
3285 hseg <= q->max_segment_size) {
3286 nr_hw_segs--;
3287 hw_size += prevbio->bi_size + bio->bi_size;
3288 } else
3289 hw_size = 0;
3290 }
3291 prevbio = bio;
3292 }
3293
3294 rq->nr_phys_segments = nr_phys_segs;
3295 rq->nr_hw_segments = nr_hw_segs;
3296}
3297
Adrian Bunk93d17d32005-06-25 14:59:10 -07003298static void blk_recalc_rq_sectors(struct request *rq, int nsect)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003299{
3300 if (blk_fs_request(rq)) {
3301 rq->hard_sector += nsect;
3302 rq->hard_nr_sectors -= nsect;
3303
3304 /*
3305 * Move the I/O submission pointers ahead if required.
3306 */
3307 if ((rq->nr_sectors >= rq->hard_nr_sectors) &&
3308 (rq->sector <= rq->hard_sector)) {
3309 rq->sector = rq->hard_sector;
3310 rq->nr_sectors = rq->hard_nr_sectors;
3311 rq->hard_cur_sectors = bio_cur_sectors(rq->bio);
3312 rq->current_nr_sectors = rq->hard_cur_sectors;
3313 rq->buffer = bio_data(rq->bio);
3314 }
3315
3316 /*
3317 * if total number of sectors is less than the first segment
3318 * size, something has gone terribly wrong
3319 */
3320 if (rq->nr_sectors < rq->current_nr_sectors) {
3321 printk("blk: request botched\n");
3322 rq->nr_sectors = rq->current_nr_sectors;
3323 }
3324 }
3325}
3326
3327static int __end_that_request_first(struct request *req, int uptodate,
3328 int nr_bytes)
3329{
3330 int total_bytes, bio_nbytes, error, next_idx = 0;
3331 struct bio *bio;
3332
Jens Axboe2056a782006-03-23 20:00:26 +01003333 blk_add_trace_rq(req->q, req, BLK_TA_COMPLETE);
3334
Linus Torvalds1da177e2005-04-16 15:20:36 -07003335 /*
3336 * extend uptodate bool to allow < 0 value to be direct io error
3337 */
3338 error = 0;
3339 if (end_io_error(uptodate))
3340 error = !uptodate ? -EIO : uptodate;
3341
3342 /*
3343 * for a REQ_BLOCK_PC request, we want to carry any eventual
3344 * sense key with us all the way through
3345 */
3346 if (!blk_pc_request(req))
3347 req->errors = 0;
3348
3349 if (!uptodate) {
Jens Axboe4aff5e22006-08-10 08:44:47 +02003350 if (blk_fs_request(req) && !(req->cmd_flags & REQ_QUIET))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003351 printk("end_request: I/O error, dev %s, sector %llu\n",
3352 req->rq_disk ? req->rq_disk->disk_name : "?",
3353 (unsigned long long)req->sector);
3354 }
3355
Jens Axboed72d9042005-11-01 08:35:42 +01003356 if (blk_fs_request(req) && req->rq_disk) {
Jens Axboea3623572005-11-01 09:26:16 +01003357 const int rw = rq_data_dir(req);
3358
Jens Axboe53e86062006-01-17 11:09:27 +01003359 disk_stat_add(req->rq_disk, sectors[rw], nr_bytes >> 9);
Jens Axboed72d9042005-11-01 08:35:42 +01003360 }
3361
Linus Torvalds1da177e2005-04-16 15:20:36 -07003362 total_bytes = bio_nbytes = 0;
3363 while ((bio = req->bio) != NULL) {
3364 int nbytes;
3365
3366 if (nr_bytes >= bio->bi_size) {
3367 req->bio = bio->bi_next;
3368 nbytes = bio->bi_size;
Tejun Heo797e7db2006-01-06 09:51:03 +01003369 if (!ordered_bio_endio(req, bio, nbytes, error))
3370 bio_endio(bio, nbytes, error);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003371 next_idx = 0;
3372 bio_nbytes = 0;
3373 } else {
3374 int idx = bio->bi_idx + next_idx;
3375
3376 if (unlikely(bio->bi_idx >= bio->bi_vcnt)) {
3377 blk_dump_rq_flags(req, "__end_that");
3378 printk("%s: bio idx %d >= vcnt %d\n",
3379 __FUNCTION__,
3380 bio->bi_idx, bio->bi_vcnt);
3381 break;
3382 }
3383
3384 nbytes = bio_iovec_idx(bio, idx)->bv_len;
3385 BIO_BUG_ON(nbytes > bio->bi_size);
3386
3387 /*
3388 * not a complete bvec done
3389 */
3390 if (unlikely(nbytes > nr_bytes)) {
3391 bio_nbytes += nr_bytes;
3392 total_bytes += nr_bytes;
3393 break;
3394 }
3395
3396 /*
3397 * advance to the next vector
3398 */
3399 next_idx++;
3400 bio_nbytes += nbytes;
3401 }
3402
3403 total_bytes += nbytes;
3404 nr_bytes -= nbytes;
3405
3406 if ((bio = req->bio)) {
3407 /*
3408 * end more in this run, or just return 'not-done'
3409 */
3410 if (unlikely(nr_bytes <= 0))
3411 break;
3412 }
3413 }
3414
3415 /*
3416 * completely done
3417 */
3418 if (!req->bio)
3419 return 0;
3420
3421 /*
3422 * if the request wasn't completed, update state
3423 */
3424 if (bio_nbytes) {
Tejun Heo797e7db2006-01-06 09:51:03 +01003425 if (!ordered_bio_endio(req, bio, bio_nbytes, error))
3426 bio_endio(bio, bio_nbytes, error);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003427 bio->bi_idx += next_idx;
3428 bio_iovec(bio)->bv_offset += nr_bytes;
3429 bio_iovec(bio)->bv_len -= nr_bytes;
3430 }
3431
3432 blk_recalc_rq_sectors(req, total_bytes >> 9);
3433 blk_recalc_rq_segments(req);
3434 return 1;
3435}
3436
3437/**
3438 * end_that_request_first - end I/O on a request
3439 * @req: the request being processed
3440 * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error
3441 * @nr_sectors: number of sectors to end I/O on
3442 *
3443 * Description:
3444 * Ends I/O on a number of sectors attached to @req, and sets it up
3445 * for the next range of segments (if any) in the cluster.
3446 *
3447 * Return:
3448 * 0 - we are done with this request, call end_that_request_last()
3449 * 1 - still buffers pending for this request
3450 **/
3451int end_that_request_first(struct request *req, int uptodate, int nr_sectors)
3452{
3453 return __end_that_request_first(req, uptodate, nr_sectors << 9);
3454}
3455
3456EXPORT_SYMBOL(end_that_request_first);
3457
3458/**
3459 * end_that_request_chunk - end I/O on a request
3460 * @req: the request being processed
3461 * @uptodate: 1 for success, 0 for I/O error, < 0 for specific error
3462 * @nr_bytes: number of bytes to complete
3463 *
3464 * Description:
3465 * Ends I/O on a number of bytes attached to @req, and sets it up
3466 * for the next range of segments (if any). Like end_that_request_first(),
3467 * but deals with bytes instead of sectors.
3468 *
3469 * Return:
3470 * 0 - we are done with this request, call end_that_request_last()
3471 * 1 - still buffers pending for this request
3472 **/
3473int end_that_request_chunk(struct request *req, int uptodate, int nr_bytes)
3474{
3475 return __end_that_request_first(req, uptodate, nr_bytes);
3476}
3477
3478EXPORT_SYMBOL(end_that_request_chunk);
3479
3480/*
Jens Axboeff856ba2006-01-09 16:02:34 +01003481 * splice the completion data to a local structure and hand off to
3482 * process_completion_queue() to complete the requests
3483 */
3484static void blk_done_softirq(struct softirq_action *h)
3485{
Oleg Nesterov626ab0e2006-06-23 02:05:55 -07003486 struct list_head *cpu_list, local_list;
Jens Axboeff856ba2006-01-09 16:02:34 +01003487
3488 local_irq_disable();
3489 cpu_list = &__get_cpu_var(blk_cpu_done);
Oleg Nesterov626ab0e2006-06-23 02:05:55 -07003490 list_replace_init(cpu_list, &local_list);
Jens Axboeff856ba2006-01-09 16:02:34 +01003491 local_irq_enable();
3492
3493 while (!list_empty(&local_list)) {
3494 struct request *rq = list_entry(local_list.next, struct request, donelist);
3495
3496 list_del_init(&rq->donelist);
3497 rq->q->softirq_done_fn(rq);
3498 }
3499}
3500
Jens Axboeff856ba2006-01-09 16:02:34 +01003501static int blk_cpu_notify(struct notifier_block *self, unsigned long action,
3502 void *hcpu)
3503{
3504 /*
3505 * If a CPU goes away, splice its entries to the current CPU
3506 * and trigger a run of the softirq
3507 */
3508 if (action == CPU_DEAD) {
3509 int cpu = (unsigned long) hcpu;
3510
3511 local_irq_disable();
3512 list_splice_init(&per_cpu(blk_cpu_done, cpu),
3513 &__get_cpu_var(blk_cpu_done));
3514 raise_softirq_irqoff(BLOCK_SOFTIRQ);
3515 local_irq_enable();
3516 }
3517
3518 return NOTIFY_OK;
3519}
3520
3521
Chandra Seetharaman054cc8a2006-06-27 02:54:07 -07003522static struct notifier_block __devinitdata blk_cpu_notifier = {
Jens Axboeff856ba2006-01-09 16:02:34 +01003523 .notifier_call = blk_cpu_notify,
3524};
3525
Jens Axboeff856ba2006-01-09 16:02:34 +01003526/**
3527 * blk_complete_request - end I/O on a request
3528 * @req: the request being processed
3529 *
3530 * Description:
3531 * Ends all I/O on a request. It does not handle partial completions,
Andreas Mohrd6e05ed2006-06-26 18:35:02 +02003532 * unless the driver actually implements this in its completion callback
Jens Axboeff856ba2006-01-09 16:02:34 +01003533 * through requeueing. Theh actual completion happens out-of-order,
3534 * through a softirq handler. The user must have registered a completion
3535 * callback through blk_queue_softirq_done().
3536 **/
3537
3538void blk_complete_request(struct request *req)
3539{
3540 struct list_head *cpu_list;
3541 unsigned long flags;
3542
3543 BUG_ON(!req->q->softirq_done_fn);
3544
3545 local_irq_save(flags);
3546
3547 cpu_list = &__get_cpu_var(blk_cpu_done);
3548 list_add_tail(&req->donelist, cpu_list);
3549 raise_softirq_irqoff(BLOCK_SOFTIRQ);
3550
3551 local_irq_restore(flags);
3552}
3553
3554EXPORT_SYMBOL(blk_complete_request);
3555
3556/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07003557 * queue lock must be held
3558 */
Tejun Heo8ffdc652006-01-06 09:49:03 +01003559void end_that_request_last(struct request *req, int uptodate)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003560{
3561 struct gendisk *disk = req->rq_disk;
Tejun Heo8ffdc652006-01-06 09:49:03 +01003562 int error;
3563
3564 /*
3565 * extend uptodate bool to allow < 0 value to be direct io error
3566 */
3567 error = 0;
3568 if (end_io_error(uptodate))
3569 error = !uptodate ? -EIO : uptodate;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003570
3571 if (unlikely(laptop_mode) && blk_fs_request(req))
3572 laptop_io_completion();
3573
Jens Axboefd0ff8a2006-05-23 11:23:49 +02003574 /*
3575 * Account IO completion. bar_rq isn't accounted as a normal
3576 * IO on queueing nor completion. Accounting the containing
3577 * request is enough.
3578 */
3579 if (disk && blk_fs_request(req) && req != &req->q->bar_rq) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003580 unsigned long duration = jiffies - req->start_time;
Jens Axboea3623572005-11-01 09:26:16 +01003581 const int rw = rq_data_dir(req);
3582
3583 __disk_stat_inc(disk, ios[rw]);
3584 __disk_stat_add(disk, ticks[rw], duration);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003585 disk_round_stats(disk);
3586 disk->in_flight--;
3587 }
3588 if (req->end_io)
Tejun Heo8ffdc652006-01-06 09:49:03 +01003589 req->end_io(req, error);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003590 else
3591 __blk_put_request(req->q, req);
3592}
3593
3594EXPORT_SYMBOL(end_that_request_last);
3595
3596void end_request(struct request *req, int uptodate)
3597{
3598 if (!end_that_request_first(req, uptodate, req->hard_cur_sectors)) {
3599 add_disk_randomness(req->rq_disk);
3600 blkdev_dequeue_request(req);
Tejun Heo8ffdc652006-01-06 09:49:03 +01003601 end_that_request_last(req, uptodate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003602 }
3603}
3604
3605EXPORT_SYMBOL(end_request);
3606
3607void blk_rq_bio_prep(request_queue_t *q, struct request *rq, struct bio *bio)
3608{
Jens Axboe4aff5e22006-08-10 08:44:47 +02003609 /* first two bits are identical in rq->cmd_flags and bio->bi_rw */
3610 rq->cmd_flags |= (bio->bi_rw & 3);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003611
3612 rq->nr_phys_segments = bio_phys_segments(q, bio);
3613 rq->nr_hw_segments = bio_hw_segments(q, bio);
3614 rq->current_nr_sectors = bio_cur_sectors(bio);
3615 rq->hard_cur_sectors = rq->current_nr_sectors;
3616 rq->hard_nr_sectors = rq->nr_sectors = bio_sectors(bio);
3617 rq->buffer = bio_data(bio);
Mike Christie0e75f902006-12-01 10:40:55 +01003618 rq->data_len = bio->bi_size;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003619
3620 rq->bio = rq->biotail = bio;
3621}
3622
3623EXPORT_SYMBOL(blk_rq_bio_prep);
3624
3625int kblockd_schedule_work(struct work_struct *work)
3626{
3627 return queue_work(kblockd_workqueue, work);
3628}
3629
3630EXPORT_SYMBOL(kblockd_schedule_work);
3631
3632void kblockd_flush(void)
3633{
3634 flush_workqueue(kblockd_workqueue);
3635}
3636EXPORT_SYMBOL(kblockd_flush);
3637
3638int __init blk_dev_init(void)
3639{
Jens Axboeff856ba2006-01-09 16:02:34 +01003640 int i;
3641
Linus Torvalds1da177e2005-04-16 15:20:36 -07003642 kblockd_workqueue = create_workqueue("kblockd");
3643 if (!kblockd_workqueue)
3644 panic("Failed to create kblockd\n");
3645
3646 request_cachep = kmem_cache_create("blkdev_requests",
3647 sizeof(struct request), 0, SLAB_PANIC, NULL, NULL);
3648
3649 requestq_cachep = kmem_cache_create("blkdev_queue",
3650 sizeof(request_queue_t), 0, SLAB_PANIC, NULL, NULL);
3651
3652 iocontext_cachep = kmem_cache_create("blkdev_ioc",
3653 sizeof(struct io_context), 0, SLAB_PANIC, NULL, NULL);
3654
KAMEZAWA Hiroyuki0a945022006-03-28 01:56:37 -08003655 for_each_possible_cpu(i)
Jens Axboeff856ba2006-01-09 16:02:34 +01003656 INIT_LIST_HEAD(&per_cpu(blk_cpu_done, i));
3657
3658 open_softirq(BLOCK_SOFTIRQ, blk_done_softirq, NULL);
Chandra Seetharaman5a67e4c2006-06-27 02:54:11 -07003659 register_hotcpu_notifier(&blk_cpu_notifier);
Jens Axboeff856ba2006-01-09 16:02:34 +01003660
Linus Torvalds1da177e2005-04-16 15:20:36 -07003661 blk_max_low_pfn = max_low_pfn;
3662 blk_max_pfn = max_pfn;
3663
3664 return 0;
3665}
3666
3667/*
3668 * IO Context helper functions
3669 */
3670void put_io_context(struct io_context *ioc)
3671{
3672 if (ioc == NULL)
3673 return;
3674
3675 BUG_ON(atomic_read(&ioc->refcount) == 0);
3676
3677 if (atomic_dec_and_test(&ioc->refcount)) {
Jens Axboee2d74ac2006-03-28 08:59:01 +02003678 struct cfq_io_context *cic;
3679
Al Viro334e94d2006-03-18 15:05:53 -05003680 rcu_read_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003681 if (ioc->aic && ioc->aic->dtor)
3682 ioc->aic->dtor(ioc->aic);
Jens Axboee2d74ac2006-03-28 08:59:01 +02003683 if (ioc->cic_root.rb_node != NULL) {
Jens Axboe7143dd42006-03-28 09:00:28 +02003684 struct rb_node *n = rb_first(&ioc->cic_root);
3685
3686 cic = rb_entry(n, struct cfq_io_context, rb_node);
Jens Axboee2d74ac2006-03-28 08:59:01 +02003687 cic->dtor(ioc);
3688 }
Al Viro334e94d2006-03-18 15:05:53 -05003689 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003690
3691 kmem_cache_free(iocontext_cachep, ioc);
3692 }
3693}
3694EXPORT_SYMBOL(put_io_context);
3695
3696/* Called by the exitting task */
3697void exit_io_context(void)
3698{
Linus Torvalds1da177e2005-04-16 15:20:36 -07003699 struct io_context *ioc;
Jens Axboee2d74ac2006-03-28 08:59:01 +02003700 struct cfq_io_context *cic;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003701
Jens Axboe22e2c502005-06-27 10:55:12 +02003702 task_lock(current);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003703 ioc = current->io_context;
3704 current->io_context = NULL;
Jens Axboe22e2c502005-06-27 10:55:12 +02003705 task_unlock(current);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003706
Oleg Nesterov25034d72006-08-29 09:15:14 +02003707 ioc->task = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003708 if (ioc->aic && ioc->aic->exit)
3709 ioc->aic->exit(ioc->aic);
Jens Axboee2d74ac2006-03-28 08:59:01 +02003710 if (ioc->cic_root.rb_node != NULL) {
3711 cic = rb_entry(rb_first(&ioc->cic_root), struct cfq_io_context, rb_node);
3712 cic->exit(ioc);
3713 }
Oleg Nesterov25034d72006-08-29 09:15:14 +02003714
Linus Torvalds1da177e2005-04-16 15:20:36 -07003715 put_io_context(ioc);
3716}
3717
3718/*
3719 * If the current task has no IO context then create one and initialise it.
Nick Pigginfb3cc432005-06-28 20:45:15 -07003720 * Otherwise, return its existing IO context.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003721 *
Nick Pigginfb3cc432005-06-28 20:45:15 -07003722 * This returned IO context doesn't have a specifically elevated refcount,
3723 * but since the current task itself holds a reference, the context can be
3724 * used in general code, so long as it stays within `current` context.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003725 */
Jens Axboeb5deef92006-07-19 23:39:40 +02003726static struct io_context *current_io_context(gfp_t gfp_flags, int node)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003727{
3728 struct task_struct *tsk = current;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003729 struct io_context *ret;
3730
Linus Torvalds1da177e2005-04-16 15:20:36 -07003731 ret = tsk->io_context;
Nick Pigginfb3cc432005-06-28 20:45:15 -07003732 if (likely(ret))
3733 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003734
Jens Axboeb5deef92006-07-19 23:39:40 +02003735 ret = kmem_cache_alloc_node(iocontext_cachep, gfp_flags, node);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003736 if (ret) {
3737 atomic_set(&ret->refcount, 1);
Jens Axboe22e2c502005-06-27 10:55:12 +02003738 ret->task = current;
Jens Axboefc463792006-08-29 09:05:44 +02003739 ret->ioprio_changed = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003740 ret->last_waited = jiffies; /* doesn't matter... */
3741 ret->nr_batch_requests = 0; /* because this is 0 */
3742 ret->aic = NULL;
Jens Axboee2d74ac2006-03-28 08:59:01 +02003743 ret->cic_root.rb_node = NULL;
Oleg Nesterov9f83e452006-08-21 08:34:15 +02003744 /* make sure set_task_ioprio() sees the settings above */
3745 smp_wmb();
Nick Pigginfb3cc432005-06-28 20:45:15 -07003746 tsk->io_context = ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003747 }
3748
3749 return ret;
3750}
Nick Pigginfb3cc432005-06-28 20:45:15 -07003751EXPORT_SYMBOL(current_io_context);
3752
3753/*
3754 * If the current task has no IO context then create one and initialise it.
3755 * If it does have a context, take a ref on it.
3756 *
3757 * This is always called in the context of the task which submitted the I/O.
3758 */
Jens Axboeb5deef92006-07-19 23:39:40 +02003759struct io_context *get_io_context(gfp_t gfp_flags, int node)
Nick Pigginfb3cc432005-06-28 20:45:15 -07003760{
3761 struct io_context *ret;
Jens Axboeb5deef92006-07-19 23:39:40 +02003762 ret = current_io_context(gfp_flags, node);
Nick Pigginfb3cc432005-06-28 20:45:15 -07003763 if (likely(ret))
3764 atomic_inc(&ret->refcount);
3765 return ret;
3766}
Linus Torvalds1da177e2005-04-16 15:20:36 -07003767EXPORT_SYMBOL(get_io_context);
3768
3769void copy_io_context(struct io_context **pdst, struct io_context **psrc)
3770{
3771 struct io_context *src = *psrc;
3772 struct io_context *dst = *pdst;
3773
3774 if (src) {
3775 BUG_ON(atomic_read(&src->refcount) == 0);
3776 atomic_inc(&src->refcount);
3777 put_io_context(dst);
3778 *pdst = src;
3779 }
3780}
3781EXPORT_SYMBOL(copy_io_context);
3782
3783void swap_io_context(struct io_context **ioc1, struct io_context **ioc2)
3784{
3785 struct io_context *temp;
3786 temp = *ioc1;
3787 *ioc1 = *ioc2;
3788 *ioc2 = temp;
3789}
3790EXPORT_SYMBOL(swap_io_context);
3791
3792/*
3793 * sysfs parts below
3794 */
3795struct queue_sysfs_entry {
3796 struct attribute attr;
3797 ssize_t (*show)(struct request_queue *, char *);
3798 ssize_t (*store)(struct request_queue *, const char *, size_t);
3799};
3800
3801static ssize_t
3802queue_var_show(unsigned int var, char *page)
3803{
3804 return sprintf(page, "%d\n", var);
3805}
3806
3807static ssize_t
3808queue_var_store(unsigned long *var, const char *page, size_t count)
3809{
3810 char *p = (char *) page;
3811
3812 *var = simple_strtoul(p, &p, 10);
3813 return count;
3814}
3815
3816static ssize_t queue_requests_show(struct request_queue *q, char *page)
3817{
3818 return queue_var_show(q->nr_requests, (page));
3819}
3820
3821static ssize_t
3822queue_requests_store(struct request_queue *q, const char *page, size_t count)
3823{
3824 struct request_list *rl = &q->rq;
Al Viroc981ff92006-03-18 13:51:29 -05003825 unsigned long nr;
3826 int ret = queue_var_store(&nr, page, count);
3827 if (nr < BLKDEV_MIN_RQ)
3828 nr = BLKDEV_MIN_RQ;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003829
Al Viroc981ff92006-03-18 13:51:29 -05003830 spin_lock_irq(q->queue_lock);
3831 q->nr_requests = nr;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003832 blk_queue_congestion_threshold(q);
3833
3834 if (rl->count[READ] >= queue_congestion_on_threshold(q))
Thomas Maier79e2de42006-10-19 23:28:15 -07003835 blk_set_queue_congested(q, READ);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003836 else if (rl->count[READ] < queue_congestion_off_threshold(q))
Thomas Maier79e2de42006-10-19 23:28:15 -07003837 blk_clear_queue_congested(q, READ);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003838
3839 if (rl->count[WRITE] >= queue_congestion_on_threshold(q))
Thomas Maier79e2de42006-10-19 23:28:15 -07003840 blk_set_queue_congested(q, WRITE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003841 else if (rl->count[WRITE] < queue_congestion_off_threshold(q))
Thomas Maier79e2de42006-10-19 23:28:15 -07003842 blk_clear_queue_congested(q, WRITE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003843
3844 if (rl->count[READ] >= q->nr_requests) {
3845 blk_set_queue_full(q, READ);
3846 } else if (rl->count[READ]+1 <= q->nr_requests) {
3847 blk_clear_queue_full(q, READ);
3848 wake_up(&rl->wait[READ]);
3849 }
3850
3851 if (rl->count[WRITE] >= q->nr_requests) {
3852 blk_set_queue_full(q, WRITE);
3853 } else if (rl->count[WRITE]+1 <= q->nr_requests) {
3854 blk_clear_queue_full(q, WRITE);
3855 wake_up(&rl->wait[WRITE]);
3856 }
Al Viroc981ff92006-03-18 13:51:29 -05003857 spin_unlock_irq(q->queue_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003858 return ret;
3859}
3860
3861static ssize_t queue_ra_show(struct request_queue *q, char *page)
3862{
3863 int ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10);
3864
3865 return queue_var_show(ra_kb, (page));
3866}
3867
3868static ssize_t
3869queue_ra_store(struct request_queue *q, const char *page, size_t count)
3870{
3871 unsigned long ra_kb;
3872 ssize_t ret = queue_var_store(&ra_kb, page, count);
3873
3874 spin_lock_irq(q->queue_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003875 q->backing_dev_info.ra_pages = ra_kb >> (PAGE_CACHE_SHIFT - 10);
3876 spin_unlock_irq(q->queue_lock);
3877
3878 return ret;
3879}
3880
3881static ssize_t queue_max_sectors_show(struct request_queue *q, char *page)
3882{
3883 int max_sectors_kb = q->max_sectors >> 1;
3884
3885 return queue_var_show(max_sectors_kb, (page));
3886}
3887
3888static ssize_t
3889queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
3890{
3891 unsigned long max_sectors_kb,
3892 max_hw_sectors_kb = q->max_hw_sectors >> 1,
3893 page_kb = 1 << (PAGE_CACHE_SHIFT - 10);
3894 ssize_t ret = queue_var_store(&max_sectors_kb, page, count);
3895 int ra_kb;
3896
3897 if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
3898 return -EINVAL;
3899 /*
3900 * Take the queue lock to update the readahead and max_sectors
3901 * values synchronously:
3902 */
3903 spin_lock_irq(q->queue_lock);
3904 /*
3905 * Trim readahead window as well, if necessary:
3906 */
3907 ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10);
3908 if (ra_kb > max_sectors_kb)
3909 q->backing_dev_info.ra_pages =
3910 max_sectors_kb >> (PAGE_CACHE_SHIFT - 10);
3911
3912 q->max_sectors = max_sectors_kb << 1;
3913 spin_unlock_irq(q->queue_lock);
3914
3915 return ret;
3916}
3917
3918static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page)
3919{
3920 int max_hw_sectors_kb = q->max_hw_sectors >> 1;
3921
3922 return queue_var_show(max_hw_sectors_kb, (page));
3923}
3924
3925
3926static struct queue_sysfs_entry queue_requests_entry = {
3927 .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
3928 .show = queue_requests_show,
3929 .store = queue_requests_store,
3930};
3931
3932static struct queue_sysfs_entry queue_ra_entry = {
3933 .attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR },
3934 .show = queue_ra_show,
3935 .store = queue_ra_store,
3936};
3937
3938static struct queue_sysfs_entry queue_max_sectors_entry = {
3939 .attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR },
3940 .show = queue_max_sectors_show,
3941 .store = queue_max_sectors_store,
3942};
3943
3944static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
3945 .attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO },
3946 .show = queue_max_hw_sectors_show,
3947};
3948
3949static struct queue_sysfs_entry queue_iosched_entry = {
3950 .attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR },
3951 .show = elv_iosched_show,
3952 .store = elv_iosched_store,
3953};
3954
3955static struct attribute *default_attrs[] = {
3956 &queue_requests_entry.attr,
3957 &queue_ra_entry.attr,
3958 &queue_max_hw_sectors_entry.attr,
3959 &queue_max_sectors_entry.attr,
3960 &queue_iosched_entry.attr,
3961 NULL,
3962};
3963
3964#define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
3965
3966static ssize_t
3967queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
3968{
3969 struct queue_sysfs_entry *entry = to_queue(attr);
Al Viro483f4af2006-03-18 18:34:37 -05003970 request_queue_t *q = container_of(kobj, struct request_queue, kobj);
3971 ssize_t res;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003972
Linus Torvalds1da177e2005-04-16 15:20:36 -07003973 if (!entry->show)
Dmitry Torokhov6c1852a2005-04-29 01:26:06 -05003974 return -EIO;
Al Viro483f4af2006-03-18 18:34:37 -05003975 mutex_lock(&q->sysfs_lock);
3976 if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
3977 mutex_unlock(&q->sysfs_lock);
3978 return -ENOENT;
3979 }
3980 res = entry->show(q, page);
3981 mutex_unlock(&q->sysfs_lock);
3982 return res;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003983}
3984
3985static ssize_t
3986queue_attr_store(struct kobject *kobj, struct attribute *attr,
3987 const char *page, size_t length)
3988{
3989 struct queue_sysfs_entry *entry = to_queue(attr);
Al Viro483f4af2006-03-18 18:34:37 -05003990 request_queue_t *q = container_of(kobj, struct request_queue, kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003991
Al Viro483f4af2006-03-18 18:34:37 -05003992 ssize_t res;
3993
Linus Torvalds1da177e2005-04-16 15:20:36 -07003994 if (!entry->store)
Dmitry Torokhov6c1852a2005-04-29 01:26:06 -05003995 return -EIO;
Al Viro483f4af2006-03-18 18:34:37 -05003996 mutex_lock(&q->sysfs_lock);
3997 if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
3998 mutex_unlock(&q->sysfs_lock);
3999 return -ENOENT;
4000 }
4001 res = entry->store(q, page, length);
4002 mutex_unlock(&q->sysfs_lock);
4003 return res;
Linus Torvalds1da177e2005-04-16 15:20:36 -07004004}
4005
4006static struct sysfs_ops queue_sysfs_ops = {
4007 .show = queue_attr_show,
4008 .store = queue_attr_store,
4009};
4010
Adrian Bunk93d17d32005-06-25 14:59:10 -07004011static struct kobj_type queue_ktype = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07004012 .sysfs_ops = &queue_sysfs_ops,
4013 .default_attrs = default_attrs,
Al Viro483f4af2006-03-18 18:34:37 -05004014 .release = blk_release_queue,
Linus Torvalds1da177e2005-04-16 15:20:36 -07004015};
4016
4017int blk_register_queue(struct gendisk *disk)
4018{
4019 int ret;
4020
4021 request_queue_t *q = disk->queue;
4022
4023 if (!q || !q->request_fn)
4024 return -ENXIO;
4025
4026 q->kobj.parent = kobject_get(&disk->kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004027
Al Viro483f4af2006-03-18 18:34:37 -05004028 ret = kobject_add(&q->kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004029 if (ret < 0)
4030 return ret;
4031
Al Viro483f4af2006-03-18 18:34:37 -05004032 kobject_uevent(&q->kobj, KOBJ_ADD);
4033
Linus Torvalds1da177e2005-04-16 15:20:36 -07004034 ret = elv_register_queue(q);
4035 if (ret) {
Al Viro483f4af2006-03-18 18:34:37 -05004036 kobject_uevent(&q->kobj, KOBJ_REMOVE);
4037 kobject_del(&q->kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004038 return ret;
4039 }
4040
4041 return 0;
4042}
4043
4044void blk_unregister_queue(struct gendisk *disk)
4045{
4046 request_queue_t *q = disk->queue;
4047
4048 if (q && q->request_fn) {
4049 elv_unregister_queue(q);
4050
Al Viro483f4af2006-03-18 18:34:37 -05004051 kobject_uevent(&q->kobj, KOBJ_REMOVE);
4052 kobject_del(&q->kobj);
Linus Torvalds1da177e2005-04-16 15:20:36 -07004053 kobject_put(&disk->kobj);
4054 }
4055}