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1 | /* | |
2 | * Functions related to segment and merge handling | |
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 <trace/events/block.h> | |
11 | ||
12 | #include "blk.h" | |
13 | ||
14 | static struct bio *blk_bio_discard_split(struct request_queue *q, | |
15 | struct bio *bio, | |
16 | struct bio_set *bs, | |
17 | unsigned *nsegs) | |
18 | { | |
19 | unsigned int max_discard_sectors, granularity; | |
20 | int alignment; | |
21 | sector_t tmp; | |
22 | unsigned split_sectors; | |
23 | ||
24 | *nsegs = 1; | |
25 | ||
26 | /* Zero-sector (unknown) and one-sector granularities are the same. */ | |
27 | granularity = max(q->limits.discard_granularity >> 9, 1U); | |
28 | ||
29 | max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9); | |
30 | max_discard_sectors -= max_discard_sectors % granularity; | |
31 | ||
32 | if (unlikely(!max_discard_sectors)) { | |
33 | /* XXX: warn */ | |
34 | return NULL; | |
35 | } | |
36 | ||
37 | if (bio_sectors(bio) <= max_discard_sectors) | |
38 | return NULL; | |
39 | ||
40 | split_sectors = max_discard_sectors; | |
41 | ||
42 | /* | |
43 | * If the next starting sector would be misaligned, stop the discard at | |
44 | * the previous aligned sector. | |
45 | */ | |
46 | alignment = (q->limits.discard_alignment >> 9) % granularity; | |
47 | ||
48 | tmp = bio->bi_iter.bi_sector + split_sectors - alignment; | |
49 | tmp = sector_div(tmp, granularity); | |
50 | ||
51 | if (split_sectors > tmp) | |
52 | split_sectors -= tmp; | |
53 | ||
54 | return bio_split(bio, split_sectors, GFP_NOIO, bs); | |
55 | } | |
56 | ||
57 | static struct bio *blk_bio_write_same_split(struct request_queue *q, | |
58 | struct bio *bio, | |
59 | struct bio_set *bs, | |
60 | unsigned *nsegs) | |
61 | { | |
62 | *nsegs = 1; | |
63 | ||
64 | if (!q->limits.max_write_same_sectors) | |
65 | return NULL; | |
66 | ||
67 | if (bio_sectors(bio) <= q->limits.max_write_same_sectors) | |
68 | return NULL; | |
69 | ||
70 | return bio_split(bio, q->limits.max_write_same_sectors, GFP_NOIO, bs); | |
71 | } | |
72 | ||
73 | static inline unsigned get_max_io_size(struct request_queue *q, | |
74 | struct bio *bio) | |
75 | { | |
76 | unsigned sectors = blk_max_size_offset(q, bio->bi_iter.bi_sector); | |
77 | unsigned mask = queue_logical_block_size(q) - 1; | |
78 | ||
79 | /* aligned to logical block size */ | |
80 | sectors &= ~(mask >> 9); | |
81 | ||
82 | return sectors; | |
83 | } | |
84 | ||
85 | static struct bio *blk_bio_segment_split(struct request_queue *q, | |
86 | struct bio *bio, | |
87 | struct bio_set *bs, | |
88 | unsigned *segs) | |
89 | { | |
90 | struct bio_vec bv, bvprv, *bvprvp = NULL; | |
91 | struct bvec_iter iter; | |
92 | unsigned seg_size = 0, nsegs = 0, sectors = 0; | |
93 | unsigned front_seg_size = bio->bi_seg_front_size; | |
94 | bool do_split = true; | |
95 | struct bio *new = NULL; | |
96 | const unsigned max_sectors = get_max_io_size(q, bio); | |
97 | ||
98 | bio_for_each_segment(bv, bio, iter) { | |
99 | /* | |
100 | * If the queue doesn't support SG gaps and adding this | |
101 | * offset would create a gap, disallow it. | |
102 | */ | |
103 | if (bvprvp && bvec_gap_to_prev(q, bvprvp, bv.bv_offset)) | |
104 | goto split; | |
105 | ||
106 | if (sectors + (bv.bv_len >> 9) > max_sectors) { | |
107 | /* | |
108 | * Consider this a new segment if we're splitting in | |
109 | * the middle of this vector. | |
110 | */ | |
111 | if (nsegs < queue_max_segments(q) && | |
112 | sectors < max_sectors) { | |
113 | nsegs++; | |
114 | sectors = max_sectors; | |
115 | } | |
116 | if (sectors) | |
117 | goto split; | |
118 | /* Make this single bvec as the 1st segment */ | |
119 | } | |
120 | ||
121 | if (bvprvp && blk_queue_cluster(q)) { | |
122 | if (seg_size + bv.bv_len > queue_max_segment_size(q)) | |
123 | goto new_segment; | |
124 | if (!BIOVEC_PHYS_MERGEABLE(bvprvp, &bv)) | |
125 | goto new_segment; | |
126 | if (!BIOVEC_SEG_BOUNDARY(q, bvprvp, &bv)) | |
127 | goto new_segment; | |
128 | ||
129 | seg_size += bv.bv_len; | |
130 | bvprv = bv; | |
131 | bvprvp = &bvprv; | |
132 | sectors += bv.bv_len >> 9; | |
133 | ||
134 | if (nsegs == 1 && seg_size > front_seg_size) | |
135 | front_seg_size = seg_size; | |
136 | continue; | |
137 | } | |
138 | new_segment: | |
139 | if (nsegs == queue_max_segments(q)) | |
140 | goto split; | |
141 | ||
142 | nsegs++; | |
143 | bvprv = bv; | |
144 | bvprvp = &bvprv; | |
145 | seg_size = bv.bv_len; | |
146 | sectors += bv.bv_len >> 9; | |
147 | ||
148 | if (nsegs == 1 && seg_size > front_seg_size) | |
149 | front_seg_size = seg_size; | |
150 | } | |
151 | ||
152 | do_split = false; | |
153 | split: | |
154 | *segs = nsegs; | |
155 | ||
156 | if (do_split) { | |
157 | new = bio_split(bio, sectors, GFP_NOIO, bs); | |
158 | if (new) | |
159 | bio = new; | |
160 | } | |
161 | ||
162 | bio->bi_seg_front_size = front_seg_size; | |
163 | if (seg_size > bio->bi_seg_back_size) | |
164 | bio->bi_seg_back_size = seg_size; | |
165 | ||
166 | return do_split ? new : NULL; | |
167 | } | |
168 | ||
169 | void blk_queue_split(struct request_queue *q, struct bio **bio, | |
170 | struct bio_set *bs) | |
171 | { | |
172 | struct bio *split, *res; | |
173 | unsigned nsegs; | |
174 | ||
175 | if ((*bio)->bi_rw & REQ_DISCARD) | |
176 | split = blk_bio_discard_split(q, *bio, bs, &nsegs); | |
177 | else if ((*bio)->bi_rw & REQ_WRITE_SAME) | |
178 | split = blk_bio_write_same_split(q, *bio, bs, &nsegs); | |
179 | else | |
180 | split = blk_bio_segment_split(q, *bio, q->bio_split, &nsegs); | |
181 | ||
182 | /* physical segments can be figured out during splitting */ | |
183 | res = split ? split : *bio; | |
184 | res->bi_phys_segments = nsegs; | |
185 | bio_set_flag(res, BIO_SEG_VALID); | |
186 | ||
187 | if (split) { | |
188 | /* there isn't chance to merge the splitted bio */ | |
189 | split->bi_rw |= REQ_NOMERGE; | |
190 | ||
191 | bio_chain(split, *bio); | |
192 | trace_block_split(q, split, (*bio)->bi_iter.bi_sector); | |
193 | generic_make_request(*bio); | |
194 | *bio = split; | |
195 | } | |
196 | } | |
197 | EXPORT_SYMBOL(blk_queue_split); | |
198 | ||
199 | static unsigned int __blk_recalc_rq_segments(struct request_queue *q, | |
200 | struct bio *bio, | |
201 | bool no_sg_merge) | |
202 | { | |
203 | struct bio_vec bv, bvprv = { NULL }; | |
204 | int cluster, prev = 0; | |
205 | unsigned int seg_size, nr_phys_segs; | |
206 | struct bio *fbio, *bbio; | |
207 | struct bvec_iter iter; | |
208 | ||
209 | if (!bio) | |
210 | return 0; | |
211 | ||
212 | /* | |
213 | * This should probably be returning 0, but blk_add_request_payload() | |
214 | * (Christoph!!!!) | |
215 | */ | |
216 | if (bio->bi_rw & REQ_DISCARD) | |
217 | return 1; | |
218 | ||
219 | if (bio->bi_rw & REQ_WRITE_SAME) | |
220 | return 1; | |
221 | ||
222 | fbio = bio; | |
223 | cluster = blk_queue_cluster(q); | |
224 | seg_size = 0; | |
225 | nr_phys_segs = 0; | |
226 | for_each_bio(bio) { | |
227 | bio_for_each_segment(bv, bio, iter) { | |
228 | /* | |
229 | * If SG merging is disabled, each bio vector is | |
230 | * a segment | |
231 | */ | |
232 | if (no_sg_merge) | |
233 | goto new_segment; | |
234 | ||
235 | if (prev && cluster) { | |
236 | if (seg_size + bv.bv_len | |
237 | > queue_max_segment_size(q)) | |
238 | goto new_segment; | |
239 | if (!BIOVEC_PHYS_MERGEABLE(&bvprv, &bv)) | |
240 | goto new_segment; | |
241 | if (!BIOVEC_SEG_BOUNDARY(q, &bvprv, &bv)) | |
242 | goto new_segment; | |
243 | ||
244 | seg_size += bv.bv_len; | |
245 | bvprv = bv; | |
246 | continue; | |
247 | } | |
248 | new_segment: | |
249 | if (nr_phys_segs == 1 && seg_size > | |
250 | fbio->bi_seg_front_size) | |
251 | fbio->bi_seg_front_size = seg_size; | |
252 | ||
253 | nr_phys_segs++; | |
254 | bvprv = bv; | |
255 | prev = 1; | |
256 | seg_size = bv.bv_len; | |
257 | } | |
258 | bbio = bio; | |
259 | } | |
260 | ||
261 | if (nr_phys_segs == 1 && seg_size > fbio->bi_seg_front_size) | |
262 | fbio->bi_seg_front_size = seg_size; | |
263 | if (seg_size > bbio->bi_seg_back_size) | |
264 | bbio->bi_seg_back_size = seg_size; | |
265 | ||
266 | return nr_phys_segs; | |
267 | } | |
268 | ||
269 | void blk_recalc_rq_segments(struct request *rq) | |
270 | { | |
271 | bool no_sg_merge = !!test_bit(QUEUE_FLAG_NO_SG_MERGE, | |
272 | &rq->q->queue_flags); | |
273 | ||
274 | rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio, | |
275 | no_sg_merge); | |
276 | } | |
277 | ||
278 | void blk_recount_segments(struct request_queue *q, struct bio *bio) | |
279 | { | |
280 | unsigned short seg_cnt; | |
281 | ||
282 | /* estimate segment number by bi_vcnt for non-cloned bio */ | |
283 | if (bio_flagged(bio, BIO_CLONED)) | |
284 | seg_cnt = bio_segments(bio); | |
285 | else | |
286 | seg_cnt = bio->bi_vcnt; | |
287 | ||
288 | if (test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags) && | |
289 | (seg_cnt < queue_max_segments(q))) | |
290 | bio->bi_phys_segments = seg_cnt; | |
291 | else { | |
292 | struct bio *nxt = bio->bi_next; | |
293 | ||
294 | bio->bi_next = NULL; | |
295 | bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, false); | |
296 | bio->bi_next = nxt; | |
297 | } | |
298 | ||
299 | bio_set_flag(bio, BIO_SEG_VALID); | |
300 | } | |
301 | EXPORT_SYMBOL(blk_recount_segments); | |
302 | ||
303 | static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio, | |
304 | struct bio *nxt) | |
305 | { | |
306 | struct bio_vec end_bv = { NULL }, nxt_bv; | |
307 | ||
308 | if (!blk_queue_cluster(q)) | |
309 | return 0; | |
310 | ||
311 | if (bio->bi_seg_back_size + nxt->bi_seg_front_size > | |
312 | queue_max_segment_size(q)) | |
313 | return 0; | |
314 | ||
315 | if (!bio_has_data(bio)) | |
316 | return 1; | |
317 | ||
318 | bio_get_last_bvec(bio, &end_bv); | |
319 | bio_get_first_bvec(nxt, &nxt_bv); | |
320 | ||
321 | if (!BIOVEC_PHYS_MERGEABLE(&end_bv, &nxt_bv)) | |
322 | return 0; | |
323 | ||
324 | /* | |
325 | * bio and nxt are contiguous in memory; check if the queue allows | |
326 | * these two to be merged into one | |
327 | */ | |
328 | if (BIOVEC_SEG_BOUNDARY(q, &end_bv, &nxt_bv)) | |
329 | return 1; | |
330 | ||
331 | return 0; | |
332 | } | |
333 | ||
334 | static inline void | |
335 | __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, | |
336 | struct scatterlist *sglist, struct bio_vec *bvprv, | |
337 | struct scatterlist **sg, int *nsegs, int *cluster) | |
338 | { | |
339 | ||
340 | int nbytes = bvec->bv_len; | |
341 | ||
342 | if (*sg && *cluster) { | |
343 | if ((*sg)->length + nbytes > queue_max_segment_size(q)) | |
344 | goto new_segment; | |
345 | ||
346 | if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) | |
347 | goto new_segment; | |
348 | if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec)) | |
349 | goto new_segment; | |
350 | ||
351 | (*sg)->length += nbytes; | |
352 | } else { | |
353 | new_segment: | |
354 | if (!*sg) | |
355 | *sg = sglist; | |
356 | else { | |
357 | /* | |
358 | * If the driver previously mapped a shorter | |
359 | * list, we could see a termination bit | |
360 | * prematurely unless it fully inits the sg | |
361 | * table on each mapping. We KNOW that there | |
362 | * must be more entries here or the driver | |
363 | * would be buggy, so force clear the | |
364 | * termination bit to avoid doing a full | |
365 | * sg_init_table() in drivers for each command. | |
366 | */ | |
367 | sg_unmark_end(*sg); | |
368 | *sg = sg_next(*sg); | |
369 | } | |
370 | ||
371 | sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); | |
372 | (*nsegs)++; | |
373 | } | |
374 | *bvprv = *bvec; | |
375 | } | |
376 | ||
377 | static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, | |
378 | struct scatterlist *sglist, | |
379 | struct scatterlist **sg) | |
380 | { | |
381 | struct bio_vec bvec, bvprv = { NULL }; | |
382 | struct bvec_iter iter; | |
383 | int nsegs, cluster; | |
384 | ||
385 | nsegs = 0; | |
386 | cluster = blk_queue_cluster(q); | |
387 | ||
388 | if (bio->bi_rw & REQ_DISCARD) { | |
389 | /* | |
390 | * This is a hack - drivers should be neither modifying the | |
391 | * biovec, nor relying on bi_vcnt - but because of | |
392 | * blk_add_request_payload(), a discard bio may or may not have | |
393 | * a payload we need to set up here (thank you Christoph) and | |
394 | * bi_vcnt is really the only way of telling if we need to. | |
395 | */ | |
396 | ||
397 | if (bio->bi_vcnt) | |
398 | goto single_segment; | |
399 | ||
400 | return 0; | |
401 | } | |
402 | ||
403 | if (bio->bi_rw & REQ_WRITE_SAME) { | |
404 | single_segment: | |
405 | *sg = sglist; | |
406 | bvec = bio_iovec(bio); | |
407 | sg_set_page(*sg, bvec.bv_page, bvec.bv_len, bvec.bv_offset); | |
408 | return 1; | |
409 | } | |
410 | ||
411 | for_each_bio(bio) | |
412 | bio_for_each_segment(bvec, bio, iter) | |
413 | __blk_segment_map_sg(q, &bvec, sglist, &bvprv, sg, | |
414 | &nsegs, &cluster); | |
415 | ||
416 | return nsegs; | |
417 | } | |
418 | ||
419 | /* | |
420 | * map a request to scatterlist, return number of sg entries setup. Caller | |
421 | * must make sure sg can hold rq->nr_phys_segments entries | |
422 | */ | |
423 | int blk_rq_map_sg(struct request_queue *q, struct request *rq, | |
424 | struct scatterlist *sglist) | |
425 | { | |
426 | struct scatterlist *sg = NULL; | |
427 | int nsegs = 0; | |
428 | ||
429 | if (rq->bio) | |
430 | nsegs = __blk_bios_map_sg(q, rq->bio, sglist, &sg); | |
431 | ||
432 | if (unlikely(rq->cmd_flags & REQ_COPY_USER) && | |
433 | (blk_rq_bytes(rq) & q->dma_pad_mask)) { | |
434 | unsigned int pad_len = | |
435 | (q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1; | |
436 | ||
437 | sg->length += pad_len; | |
438 | rq->extra_len += pad_len; | |
439 | } | |
440 | ||
441 | if (q->dma_drain_size && q->dma_drain_needed(rq)) { | |
442 | if (rq->cmd_flags & REQ_WRITE) | |
443 | memset(q->dma_drain_buffer, 0, q->dma_drain_size); | |
444 | ||
445 | sg_unmark_end(sg); | |
446 | sg = sg_next(sg); | |
447 | sg_set_page(sg, virt_to_page(q->dma_drain_buffer), | |
448 | q->dma_drain_size, | |
449 | ((unsigned long)q->dma_drain_buffer) & | |
450 | (PAGE_SIZE - 1)); | |
451 | nsegs++; | |
452 | rq->extra_len += q->dma_drain_size; | |
453 | } | |
454 | ||
455 | if (sg) | |
456 | sg_mark_end(sg); | |
457 | ||
458 | /* | |
459 | * Something must have been wrong if the figured number of | |
460 | * segment is bigger than number of req's physical segments | |
461 | */ | |
462 | WARN_ON(nsegs > rq->nr_phys_segments); | |
463 | ||
464 | return nsegs; | |
465 | } | |
466 | EXPORT_SYMBOL(blk_rq_map_sg); | |
467 | ||
468 | static inline int ll_new_hw_segment(struct request_queue *q, | |
469 | struct request *req, | |
470 | struct bio *bio) | |
471 | { | |
472 | int nr_phys_segs = bio_phys_segments(q, bio); | |
473 | ||
474 | if (req->nr_phys_segments + nr_phys_segs > queue_max_segments(q)) | |
475 | goto no_merge; | |
476 | ||
477 | if (blk_integrity_merge_bio(q, req, bio) == false) | |
478 | goto no_merge; | |
479 | ||
480 | /* | |
481 | * This will form the start of a new hw segment. Bump both | |
482 | * counters. | |
483 | */ | |
484 | req->nr_phys_segments += nr_phys_segs; | |
485 | return 1; | |
486 | ||
487 | no_merge: | |
488 | req->cmd_flags |= REQ_NOMERGE; | |
489 | if (req == q->last_merge) | |
490 | q->last_merge = NULL; | |
491 | return 0; | |
492 | } | |
493 | ||
494 | int ll_back_merge_fn(struct request_queue *q, struct request *req, | |
495 | struct bio *bio) | |
496 | { | |
497 | if (req_gap_back_merge(req, bio)) | |
498 | return 0; | |
499 | if (blk_integrity_rq(req) && | |
500 | integrity_req_gap_back_merge(req, bio)) | |
501 | return 0; | |
502 | if (blk_rq_sectors(req) + bio_sectors(bio) > | |
503 | blk_rq_get_max_sectors(req)) { | |
504 | req->cmd_flags |= REQ_NOMERGE; | |
505 | if (req == q->last_merge) | |
506 | q->last_merge = NULL; | |
507 | return 0; | |
508 | } | |
509 | if (!bio_flagged(req->biotail, BIO_SEG_VALID)) | |
510 | blk_recount_segments(q, req->biotail); | |
511 | if (!bio_flagged(bio, BIO_SEG_VALID)) | |
512 | blk_recount_segments(q, bio); | |
513 | ||
514 | return ll_new_hw_segment(q, req, bio); | |
515 | } | |
516 | ||
517 | int ll_front_merge_fn(struct request_queue *q, struct request *req, | |
518 | struct bio *bio) | |
519 | { | |
520 | ||
521 | if (req_gap_front_merge(req, bio)) | |
522 | return 0; | |
523 | if (blk_integrity_rq(req) && | |
524 | integrity_req_gap_front_merge(req, bio)) | |
525 | return 0; | |
526 | if (blk_rq_sectors(req) + bio_sectors(bio) > | |
527 | blk_rq_get_max_sectors(req)) { | |
528 | req->cmd_flags |= REQ_NOMERGE; | |
529 | if (req == q->last_merge) | |
530 | q->last_merge = NULL; | |
531 | return 0; | |
532 | } | |
533 | if (!bio_flagged(bio, BIO_SEG_VALID)) | |
534 | blk_recount_segments(q, bio); | |
535 | if (!bio_flagged(req->bio, BIO_SEG_VALID)) | |
536 | blk_recount_segments(q, req->bio); | |
537 | ||
538 | return ll_new_hw_segment(q, req, bio); | |
539 | } | |
540 | ||
541 | /* | |
542 | * blk-mq uses req->special to carry normal driver per-request payload, it | |
543 | * does not indicate a prepared command that we cannot merge with. | |
544 | */ | |
545 | static bool req_no_special_merge(struct request *req) | |
546 | { | |
547 | struct request_queue *q = req->q; | |
548 | ||
549 | return !q->mq_ops && req->special; | |
550 | } | |
551 | ||
552 | static int ll_merge_requests_fn(struct request_queue *q, struct request *req, | |
553 | struct request *next) | |
554 | { | |
555 | int total_phys_segments; | |
556 | unsigned int seg_size = | |
557 | req->biotail->bi_seg_back_size + next->bio->bi_seg_front_size; | |
558 | ||
559 | /* | |
560 | * First check if the either of the requests are re-queued | |
561 | * requests. Can't merge them if they are. | |
562 | */ | |
563 | if (req_no_special_merge(req) || req_no_special_merge(next)) | |
564 | return 0; | |
565 | ||
566 | if (req_gap_back_merge(req, next->bio)) | |
567 | return 0; | |
568 | ||
569 | /* | |
570 | * Will it become too large? | |
571 | */ | |
572 | if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > | |
573 | blk_rq_get_max_sectors(req)) | |
574 | return 0; | |
575 | ||
576 | total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; | |
577 | if (blk_phys_contig_segment(q, req->biotail, next->bio)) { | |
578 | if (req->nr_phys_segments == 1) | |
579 | req->bio->bi_seg_front_size = seg_size; | |
580 | if (next->nr_phys_segments == 1) | |
581 | next->biotail->bi_seg_back_size = seg_size; | |
582 | total_phys_segments--; | |
583 | } | |
584 | ||
585 | if (total_phys_segments > queue_max_segments(q)) | |
586 | return 0; | |
587 | ||
588 | if (blk_integrity_merge_rq(q, req, next) == false) | |
589 | return 0; | |
590 | ||
591 | /* Merge is OK... */ | |
592 | req->nr_phys_segments = total_phys_segments; | |
593 | return 1; | |
594 | } | |
595 | ||
596 | /** | |
597 | * blk_rq_set_mixed_merge - mark a request as mixed merge | |
598 | * @rq: request to mark as mixed merge | |
599 | * | |
600 | * Description: | |
601 | * @rq is about to be mixed merged. Make sure the attributes | |
602 | * which can be mixed are set in each bio and mark @rq as mixed | |
603 | * merged. | |
604 | */ | |
605 | void blk_rq_set_mixed_merge(struct request *rq) | |
606 | { | |
607 | unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; | |
608 | struct bio *bio; | |
609 | ||
610 | if (rq->cmd_flags & REQ_MIXED_MERGE) | |
611 | return; | |
612 | ||
613 | /* | |
614 | * @rq will no longer represent mixable attributes for all the | |
615 | * contained bios. It will just track those of the first one. | |
616 | * Distributes the attributs to each bio. | |
617 | */ | |
618 | for (bio = rq->bio; bio; bio = bio->bi_next) { | |
619 | WARN_ON_ONCE((bio->bi_rw & REQ_FAILFAST_MASK) && | |
620 | (bio->bi_rw & REQ_FAILFAST_MASK) != ff); | |
621 | bio->bi_rw |= ff; | |
622 | } | |
623 | rq->cmd_flags |= REQ_MIXED_MERGE; | |
624 | } | |
625 | ||
626 | static void blk_account_io_merge(struct request *req) | |
627 | { | |
628 | if (blk_do_io_stat(req)) { | |
629 | struct hd_struct *part; | |
630 | int cpu; | |
631 | ||
632 | cpu = part_stat_lock(); | |
633 | part = req->part; | |
634 | ||
635 | part_round_stats(cpu, part); | |
636 | part_dec_in_flight(part, rq_data_dir(req)); | |
637 | ||
638 | hd_struct_put(part); | |
639 | part_stat_unlock(); | |
640 | } | |
641 | } | |
642 | ||
643 | /* | |
644 | * Has to be called with the request spinlock acquired | |
645 | */ | |
646 | static int attempt_merge(struct request_queue *q, struct request *req, | |
647 | struct request *next) | |
648 | { | |
649 | if (!rq_mergeable(req) || !rq_mergeable(next)) | |
650 | return 0; | |
651 | ||
652 | if (!blk_check_merge_flags(req->cmd_flags, next->cmd_flags)) | |
653 | return 0; | |
654 | ||
655 | /* | |
656 | * not contiguous | |
657 | */ | |
658 | if (blk_rq_pos(req) + blk_rq_sectors(req) != blk_rq_pos(next)) | |
659 | return 0; | |
660 | ||
661 | if (rq_data_dir(req) != rq_data_dir(next) | |
662 | || req->rq_disk != next->rq_disk | |
663 | || req_no_special_merge(next)) | |
664 | return 0; | |
665 | ||
666 | if (req->cmd_flags & REQ_WRITE_SAME && | |
667 | !blk_write_same_mergeable(req->bio, next->bio)) | |
668 | return 0; | |
669 | ||
670 | /* | |
671 | * If we are allowed to merge, then append bio list | |
672 | * from next to rq and release next. merge_requests_fn | |
673 | * will have updated segment counts, update sector | |
674 | * counts here. | |
675 | */ | |
676 | if (!ll_merge_requests_fn(q, req, next)) | |
677 | return 0; | |
678 | ||
679 | /* | |
680 | * If failfast settings disagree or any of the two is already | |
681 | * a mixed merge, mark both as mixed before proceeding. This | |
682 | * makes sure that all involved bios have mixable attributes | |
683 | * set properly. | |
684 | */ | |
685 | if ((req->cmd_flags | next->cmd_flags) & REQ_MIXED_MERGE || | |
686 | (req->cmd_flags & REQ_FAILFAST_MASK) != | |
687 | (next->cmd_flags & REQ_FAILFAST_MASK)) { | |
688 | blk_rq_set_mixed_merge(req); | |
689 | blk_rq_set_mixed_merge(next); | |
690 | } | |
691 | ||
692 | /* | |
693 | * At this point we have either done a back merge | |
694 | * or front merge. We need the smaller start_time of | |
695 | * the merged requests to be the current request | |
696 | * for accounting purposes. | |
697 | */ | |
698 | if (time_after(req->start_time, next->start_time)) | |
699 | req->start_time = next->start_time; | |
700 | ||
701 | req->biotail->bi_next = next->bio; | |
702 | req->biotail = next->biotail; | |
703 | ||
704 | req->__data_len += blk_rq_bytes(next); | |
705 | ||
706 | elv_merge_requests(q, req, next); | |
707 | ||
708 | /* | |
709 | * 'next' is going away, so update stats accordingly | |
710 | */ | |
711 | blk_account_io_merge(next); | |
712 | ||
713 | req->ioprio = ioprio_best(req->ioprio, next->ioprio); | |
714 | if (blk_rq_cpu_valid(next)) | |
715 | req->cpu = next->cpu; | |
716 | ||
717 | /* owner-ship of bio passed from next to req */ | |
718 | next->bio = NULL; | |
719 | __blk_put_request(q, next); | |
720 | return 1; | |
721 | } | |
722 | ||
723 | int attempt_back_merge(struct request_queue *q, struct request *rq) | |
724 | { | |
725 | struct request *next = elv_latter_request(q, rq); | |
726 | ||
727 | if (next) | |
728 | return attempt_merge(q, rq, next); | |
729 | ||
730 | return 0; | |
731 | } | |
732 | ||
733 | int attempt_front_merge(struct request_queue *q, struct request *rq) | |
734 | { | |
735 | struct request *prev = elv_former_request(q, rq); | |
736 | ||
737 | if (prev) | |
738 | return attempt_merge(q, prev, rq); | |
739 | ||
740 | return 0; | |
741 | } | |
742 | ||
743 | int blk_attempt_req_merge(struct request_queue *q, struct request *rq, | |
744 | struct request *next) | |
745 | { | |
746 | return attempt_merge(q, rq, next); | |
747 | } | |
748 | ||
749 | bool blk_rq_merge_ok(struct request *rq, struct bio *bio) | |
750 | { | |
751 | if (!rq_mergeable(rq) || !bio_mergeable(bio)) | |
752 | return false; | |
753 | ||
754 | if (!blk_check_merge_flags(rq->cmd_flags, bio->bi_rw)) | |
755 | return false; | |
756 | ||
757 | /* different data direction or already started, don't merge */ | |
758 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
759 | return false; | |
760 | ||
761 | /* must be same device and not a special request */ | |
762 | if (rq->rq_disk != bio->bi_bdev->bd_disk || req_no_special_merge(rq)) | |
763 | return false; | |
764 | ||
765 | /* only merge integrity protected bio into ditto rq */ | |
766 | if (blk_integrity_merge_bio(rq->q, rq, bio) == false) | |
767 | return false; | |
768 | ||
769 | /* must be using the same buffer */ | |
770 | if (rq->cmd_flags & REQ_WRITE_SAME && | |
771 | !blk_write_same_mergeable(rq->bio, bio)) | |
772 | return false; | |
773 | ||
774 | return true; | |
775 | } | |
776 | ||
777 | int blk_try_merge(struct request *rq, struct bio *bio) | |
778 | { | |
779 | if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector) | |
780 | return ELEVATOR_BACK_MERGE; | |
781 | else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector) | |
782 | return ELEVATOR_FRONT_MERGE; | |
783 | return ELEVATOR_NO_MERGE; | |
784 | } |