1
2
3
4#include <linux/kernel.h>
5#include <linux/module.h>
6#include <linux/bio.h>
7#include <linux/blkdev.h>
8#include <linux/scatterlist.h>
9
10#include "blk.h"
11
12static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
13 struct bio *bio)
14{
15 struct bio_vec *bv, *bvprv = NULL;
16 int cluster, i, high, highprv = 1;
17 unsigned int seg_size, nr_phys_segs;
18 struct bio *fbio, *bbio;
19
20 if (!bio)
21 return 0;
22
23 fbio = bio;
24 cluster = blk_queue_cluster(q);
25 seg_size = 0;
26 nr_phys_segs = 0;
27 for_each_bio(bio) {
28 bio_for_each_segment(bv, bio, i) {
29
30
31
32
33
34 high = page_to_pfn(bv->bv_page) > queue_bounce_pfn(q);
35 if (high || highprv)
36 goto new_segment;
37 if (cluster) {
38 if (seg_size + bv->bv_len
39 > queue_max_segment_size(q))
40 goto new_segment;
41 if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv))
42 goto new_segment;
43 if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv))
44 goto new_segment;
45
46 seg_size += bv->bv_len;
47 bvprv = bv;
48 continue;
49 }
50new_segment:
51 if (nr_phys_segs == 1 && seg_size >
52 fbio->bi_seg_front_size)
53 fbio->bi_seg_front_size = seg_size;
54
55 nr_phys_segs++;
56 bvprv = bv;
57 seg_size = bv->bv_len;
58 highprv = high;
59 }
60 bbio = bio;
61 }
62
63 if (nr_phys_segs == 1 && seg_size > fbio->bi_seg_front_size)
64 fbio->bi_seg_front_size = seg_size;
65 if (seg_size > bbio->bi_seg_back_size)
66 bbio->bi_seg_back_size = seg_size;
67
68 return nr_phys_segs;
69}
70
71void blk_recalc_rq_segments(struct request *rq)
72{
73 rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio);
74}
75
76void blk_recount_segments(struct request_queue *q, struct bio *bio)
77{
78 struct bio *nxt = bio->bi_next;
79
80 bio->bi_next = NULL;
81 bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio);
82 bio->bi_next = nxt;
83 bio->bi_flags |= (1 << BIO_SEG_VALID);
84}
85EXPORT_SYMBOL(blk_recount_segments);
86
87static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio,
88 struct bio *nxt)
89{
90 if (!blk_queue_cluster(q))
91 return 0;
92
93 if (bio->bi_seg_back_size + nxt->bi_seg_front_size >
94 queue_max_segment_size(q))
95 return 0;
96
97 if (!bio_has_data(bio))
98 return 1;
99
100 if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)))
101 return 0;
102
103
104
105
106
107 if (BIO_SEG_BOUNDARY(q, bio, nxt))
108 return 1;
109
110 return 0;
111}
112
113
114
115
116
117int blk_rq_map_sg(struct request_queue *q, struct request *rq,
118 struct scatterlist *sglist)
119{
120 struct bio_vec *bvec, *bvprv;
121 struct req_iterator iter;
122 struct scatterlist *sg;
123 int nsegs, cluster;
124
125 nsegs = 0;
126 cluster = blk_queue_cluster(q);
127
128
129
130
131 bvprv = NULL;
132 sg = NULL;
133 rq_for_each_segment(bvec, rq, iter) {
134 int nbytes = bvec->bv_len;
135
136 if (bvprv && cluster) {
137 if (sg->length + nbytes > queue_max_segment_size(q))
138 goto new_segment;
139
140 if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec))
141 goto new_segment;
142 if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec))
143 goto new_segment;
144
145 sg->length += nbytes;
146 } else {
147new_segment:
148 if (!sg)
149 sg = sglist;
150 else {
151
152
153
154
155
156
157
158
159
160
161 sg->page_link &= ~0x02;
162 sg = sg_next(sg);
163 }
164
165 sg_set_page(sg, bvec->bv_page, nbytes, bvec->bv_offset);
166 nsegs++;
167 }
168 bvprv = bvec;
169 }
170
171
172 if (unlikely(rq->cmd_flags & REQ_COPY_USER) &&
173 (blk_rq_bytes(rq) & q->dma_pad_mask)) {
174 unsigned int pad_len =
175 (q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1;
176
177 sg->length += pad_len;
178 rq->extra_len += pad_len;
179 }
180
181 if (q->dma_drain_size && q->dma_drain_needed(rq)) {
182 if (rq->cmd_flags & REQ_WRITE)
183 memset(q->dma_drain_buffer, 0, q->dma_drain_size);
184
185 sg->page_link &= ~0x02;
186 sg = sg_next(sg);
187 sg_set_page(sg, virt_to_page(q->dma_drain_buffer),
188 q->dma_drain_size,
189 ((unsigned long)q->dma_drain_buffer) &
190 (PAGE_SIZE - 1));
191 nsegs++;
192 rq->extra_len += q->dma_drain_size;
193 }
194
195 if (sg)
196 sg_mark_end(sg);
197
198 return nsegs;
199}
200EXPORT_SYMBOL(blk_rq_map_sg);
201
202static inline int ll_new_hw_segment(struct request_queue *q,
203 struct request *req,
204 struct bio *bio)
205{
206 int nr_phys_segs = bio_phys_segments(q, bio);
207
208 if (req->nr_phys_segments + nr_phys_segs > queue_max_segments(q))
209 goto no_merge;
210
211 if (bio_integrity(bio) && blk_integrity_merge_bio(q, req, bio))
212 goto no_merge;
213
214
215
216
217
218 req->nr_phys_segments += nr_phys_segs;
219 return 1;
220
221no_merge:
222 req->cmd_flags |= REQ_NOMERGE;
223 if (req == q->last_merge)
224 q->last_merge = NULL;
225 return 0;
226}
227
228int ll_back_merge_fn(struct request_queue *q, struct request *req,
229 struct bio *bio)
230{
231 unsigned short max_sectors;
232
233 if (unlikely(req->cmd_type == REQ_TYPE_BLOCK_PC))
234 max_sectors = queue_max_hw_sectors(q);
235 else
236 max_sectors = queue_max_sectors(q);
237
238 if (blk_rq_sectors(req) + bio_sectors(bio) > max_sectors) {
239 req->cmd_flags |= REQ_NOMERGE;
240 if (req == q->last_merge)
241 q->last_merge = NULL;
242 return 0;
243 }
244 if (!bio_flagged(req->biotail, BIO_SEG_VALID))
245 blk_recount_segments(q, req->biotail);
246 if (!bio_flagged(bio, BIO_SEG_VALID))
247 blk_recount_segments(q, bio);
248
249 return ll_new_hw_segment(q, req, bio);
250}
251
252int ll_front_merge_fn(struct request_queue *q, struct request *req,
253 struct bio *bio)
254{
255 unsigned short max_sectors;
256
257 if (unlikely(req->cmd_type == REQ_TYPE_BLOCK_PC))
258 max_sectors = queue_max_hw_sectors(q);
259 else
260 max_sectors = queue_max_sectors(q);
261
262
263 if (blk_rq_sectors(req) + bio_sectors(bio) > max_sectors) {
264 req->cmd_flags |= REQ_NOMERGE;
265 if (req == q->last_merge)
266 q->last_merge = NULL;
267 return 0;
268 }
269 if (!bio_flagged(bio, BIO_SEG_VALID))
270 blk_recount_segments(q, bio);
271 if (!bio_flagged(req->bio, BIO_SEG_VALID))
272 blk_recount_segments(q, req->bio);
273
274 return ll_new_hw_segment(q, req, bio);
275}
276
277static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
278 struct request *next)
279{
280 int total_phys_segments;
281 unsigned int seg_size =
282 req->biotail->bi_seg_back_size + next->bio->bi_seg_front_size;
283
284
285
286
287
288 if (req->special || next->special)
289 return 0;
290
291
292
293
294 if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > queue_max_sectors(q))
295 return 0;
296
297 total_phys_segments = req->nr_phys_segments + next->nr_phys_segments;
298 if (blk_phys_contig_segment(q, req->biotail, next->bio)) {
299 if (req->nr_phys_segments == 1)
300 req->bio->bi_seg_front_size = seg_size;
301 if (next->nr_phys_segments == 1)
302 next->biotail->bi_seg_back_size = seg_size;
303 total_phys_segments--;
304 }
305
306 if (total_phys_segments > queue_max_segments(q))
307 return 0;
308
309 if (blk_integrity_rq(req) && blk_integrity_merge_rq(q, req, next))
310 return 0;
311
312
313 req->nr_phys_segments = total_phys_segments;
314 return 1;
315}
316
317
318
319
320
321
322
323
324
325
326void blk_rq_set_mixed_merge(struct request *rq)
327{
328 unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK;
329 struct bio *bio;
330
331 if (rq->cmd_flags & REQ_MIXED_MERGE)
332 return;
333
334
335
336
337
338
339 for (bio = rq->bio; bio; bio = bio->bi_next) {
340 WARN_ON_ONCE((bio->bi_rw & REQ_FAILFAST_MASK) &&
341 (bio->bi_rw & REQ_FAILFAST_MASK) != ff);
342 bio->bi_rw |= ff;
343 }
344 rq->cmd_flags |= REQ_MIXED_MERGE;
345}
346
347static void blk_account_io_merge(struct request *req)
348{
349 if (blk_do_io_stat(req)) {
350 struct hd_struct *part;
351 int cpu;
352
353 cpu = part_stat_lock();
354 part = req->part;
355
356 part_round_stats(cpu, part);
357 part_dec_in_flight(part, rq_data_dir(req));
358
359 hd_struct_put(part);
360 part_stat_unlock();
361 }
362}
363
364
365
366
367static int attempt_merge(struct request_queue *q, struct request *req,
368 struct request *next)
369{
370 if (!rq_mergeable(req) || !rq_mergeable(next))
371 return 0;
372
373
374
375
376 if ((req->cmd_flags & REQ_DISCARD) != (next->cmd_flags & REQ_DISCARD))
377 return 0;
378
379
380
381
382 if ((req->cmd_flags & REQ_SECURE) != (next->cmd_flags & REQ_SECURE))
383 return 0;
384
385
386
387
388 if (blk_rq_pos(req) + blk_rq_sectors(req) != blk_rq_pos(next))
389 return 0;
390
391 if (rq_data_dir(req) != rq_data_dir(next)
392 || req->rq_disk != next->rq_disk
393 || next->special)
394 return 0;
395
396
397
398
399
400
401
402 if (!ll_merge_requests_fn(q, req, next))
403 return 0;
404
405
406
407
408
409
410
411 if ((req->cmd_flags | next->cmd_flags) & REQ_MIXED_MERGE ||
412 (req->cmd_flags & REQ_FAILFAST_MASK) !=
413 (next->cmd_flags & REQ_FAILFAST_MASK)) {
414 blk_rq_set_mixed_merge(req);
415 blk_rq_set_mixed_merge(next);
416 }
417
418
419
420
421
422
423
424 if (time_after(req->start_time, next->start_time))
425 req->start_time = next->start_time;
426
427 req->biotail->bi_next = next->bio;
428 req->biotail = next->biotail;
429
430 req->__data_len += blk_rq_bytes(next);
431
432 elv_merge_requests(q, req, next);
433
434
435
436
437 blk_account_io_merge(next);
438
439 req->ioprio = ioprio_best(req->ioprio, next->ioprio);
440 if (blk_rq_cpu_valid(next))
441 req->cpu = next->cpu;
442
443
444 next->bio = NULL;
445 __blk_put_request(q, next);
446 return 1;
447}
448
449int attempt_back_merge(struct request_queue *q, struct request *rq)
450{
451 struct request *next = elv_latter_request(q, rq);
452
453 if (next)
454 return attempt_merge(q, rq, next);
455
456 return 0;
457}
458
459int attempt_front_merge(struct request_queue *q, struct request *rq)
460{
461 struct request *prev = elv_former_request(q, rq);
462
463 if (prev)
464 return attempt_merge(q, prev, rq);
465
466 return 0;
467}
468
469int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
470 struct request *next)
471{
472 return attempt_merge(q, rq, next);
473}
474
475bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
476{
477 if (!rq_mergeable(rq))
478 return false;
479
480
481 if ((bio->bi_rw & REQ_DISCARD) != (rq->bio->bi_rw & REQ_DISCARD))
482 return false;
483
484
485 if ((bio->bi_rw & REQ_SECURE) != (rq->bio->bi_rw & REQ_SECURE))
486 return false;
487
488
489 if (bio_data_dir(bio) != rq_data_dir(rq))
490 return false;
491
492
493 if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special)
494 return false;
495
496
497 if (bio_integrity(bio) != blk_integrity_rq(rq))
498 return false;
499
500 return true;
501}
502
503int blk_try_merge(struct request *rq, struct bio *bio)
504{
505 if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_sector)
506 return ELEVATOR_BACK_MERGE;
507 else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_sector)
508 return ELEVATOR_FRONT_MERGE;
509 return ELEVATOR_NO_MERGE;
510}
511