Commit | Line | Data |
---|---|---|
d6d48196 JA |
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 "blk.h" | |
11 | ||
54efd50b KO |
12 | static struct bio *blk_bio_discard_split(struct request_queue *q, |
13 | struct bio *bio, | |
14 | struct bio_set *bs) | |
15 | { | |
16 | unsigned int max_discard_sectors, granularity; | |
17 | int alignment; | |
18 | sector_t tmp; | |
19 | unsigned split_sectors; | |
20 | ||
21 | /* Zero-sector (unknown) and one-sector granularities are the same. */ | |
22 | granularity = max(q->limits.discard_granularity >> 9, 1U); | |
23 | ||
24 | max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9); | |
25 | max_discard_sectors -= max_discard_sectors % granularity; | |
26 | ||
27 | if (unlikely(!max_discard_sectors)) { | |
28 | /* XXX: warn */ | |
29 | return NULL; | |
30 | } | |
31 | ||
32 | if (bio_sectors(bio) <= max_discard_sectors) | |
33 | return NULL; | |
34 | ||
35 | split_sectors = max_discard_sectors; | |
36 | ||
37 | /* | |
38 | * If the next starting sector would be misaligned, stop the discard at | |
39 | * the previous aligned sector. | |
40 | */ | |
41 | alignment = (q->limits.discard_alignment >> 9) % granularity; | |
42 | ||
43 | tmp = bio->bi_iter.bi_sector + split_sectors - alignment; | |
44 | tmp = sector_div(tmp, granularity); | |
45 | ||
46 | if (split_sectors > tmp) | |
47 | split_sectors -= tmp; | |
48 | ||
49 | return bio_split(bio, split_sectors, GFP_NOIO, bs); | |
50 | } | |
51 | ||
52 | static struct bio *blk_bio_write_same_split(struct request_queue *q, | |
53 | struct bio *bio, | |
54 | struct bio_set *bs) | |
55 | { | |
56 | if (!q->limits.max_write_same_sectors) | |
57 | return NULL; | |
58 | ||
59 | if (bio_sectors(bio) <= q->limits.max_write_same_sectors) | |
60 | return NULL; | |
61 | ||
62 | return bio_split(bio, q->limits.max_write_same_sectors, GFP_NOIO, bs); | |
63 | } | |
64 | ||
65 | static struct bio *blk_bio_segment_split(struct request_queue *q, | |
66 | struct bio *bio, | |
67 | struct bio_set *bs) | |
68 | { | |
69 | struct bio *split; | |
70 | struct bio_vec bv, bvprv; | |
71 | struct bvec_iter iter; | |
8ae12666 | 72 | unsigned seg_size = 0, nsegs = 0, sectors = 0; |
54efd50b KO |
73 | int prev = 0; |
74 | ||
54efd50b | 75 | bio_for_each_segment(bv, bio, iter) { |
8ae12666 | 76 | sectors += bv.bv_len >> 9; |
54efd50b | 77 | |
8ae12666 | 78 | if (sectors > queue_max_sectors(q)) |
54efd50b KO |
79 | goto split; |
80 | ||
81 | /* | |
82 | * If the queue doesn't support SG gaps and adding this | |
83 | * offset would create a gap, disallow it. | |
84 | */ | |
03100aad | 85 | if (prev && bvec_gap_to_prev(q, &bvprv, bv.bv_offset)) |
54efd50b KO |
86 | goto split; |
87 | ||
88 | if (prev && blk_queue_cluster(q)) { | |
89 | if (seg_size + bv.bv_len > queue_max_segment_size(q)) | |
90 | goto new_segment; | |
91 | if (!BIOVEC_PHYS_MERGEABLE(&bvprv, &bv)) | |
92 | goto new_segment; | |
93 | if (!BIOVEC_SEG_BOUNDARY(q, &bvprv, &bv)) | |
94 | goto new_segment; | |
95 | ||
96 | seg_size += bv.bv_len; | |
97 | bvprv = bv; | |
98 | prev = 1; | |
99 | continue; | |
100 | } | |
101 | new_segment: | |
102 | if (nsegs == queue_max_segments(q)) | |
103 | goto split; | |
104 | ||
105 | nsegs++; | |
106 | bvprv = bv; | |
107 | prev = 1; | |
108 | seg_size = bv.bv_len; | |
109 | } | |
110 | ||
111 | return NULL; | |
112 | split: | |
113 | split = bio_clone_bioset(bio, GFP_NOIO, bs); | |
114 | ||
115 | split->bi_iter.bi_size -= iter.bi_size; | |
116 | bio->bi_iter = iter; | |
117 | ||
118 | if (bio_integrity(bio)) { | |
119 | bio_integrity_advance(bio, split->bi_iter.bi_size); | |
120 | bio_integrity_trim(split, 0, bio_sectors(split)); | |
121 | } | |
122 | ||
123 | return split; | |
124 | } | |
125 | ||
126 | void blk_queue_split(struct request_queue *q, struct bio **bio, | |
127 | struct bio_set *bs) | |
128 | { | |
129 | struct bio *split; | |
130 | ||
131 | if ((*bio)->bi_rw & REQ_DISCARD) | |
132 | split = blk_bio_discard_split(q, *bio, bs); | |
133 | else if ((*bio)->bi_rw & REQ_WRITE_SAME) | |
134 | split = blk_bio_write_same_split(q, *bio, bs); | |
135 | else | |
136 | split = blk_bio_segment_split(q, *bio, q->bio_split); | |
137 | ||
138 | if (split) { | |
139 | bio_chain(split, *bio); | |
140 | generic_make_request(*bio); | |
141 | *bio = split; | |
142 | } | |
143 | } | |
144 | EXPORT_SYMBOL(blk_queue_split); | |
145 | ||
1e428079 | 146 | static unsigned int __blk_recalc_rq_segments(struct request_queue *q, |
07388549 ML |
147 | struct bio *bio, |
148 | bool no_sg_merge) | |
d6d48196 | 149 | { |
7988613b | 150 | struct bio_vec bv, bvprv = { NULL }; |
54efd50b | 151 | int cluster, prev = 0; |
1e428079 | 152 | unsigned int seg_size, nr_phys_segs; |
59247eae | 153 | struct bio *fbio, *bbio; |
7988613b | 154 | struct bvec_iter iter; |
d6d48196 | 155 | |
1e428079 JA |
156 | if (!bio) |
157 | return 0; | |
d6d48196 | 158 | |
5cb8850c KO |
159 | /* |
160 | * This should probably be returning 0, but blk_add_request_payload() | |
161 | * (Christoph!!!!) | |
162 | */ | |
163 | if (bio->bi_rw & REQ_DISCARD) | |
164 | return 1; | |
165 | ||
166 | if (bio->bi_rw & REQ_WRITE_SAME) | |
167 | return 1; | |
168 | ||
1e428079 | 169 | fbio = bio; |
e692cb66 | 170 | cluster = blk_queue_cluster(q); |
5df97b91 | 171 | seg_size = 0; |
2c8919de | 172 | nr_phys_segs = 0; |
1e428079 | 173 | for_each_bio(bio) { |
7988613b | 174 | bio_for_each_segment(bv, bio, iter) { |
05f1dd53 JA |
175 | /* |
176 | * If SG merging is disabled, each bio vector is | |
177 | * a segment | |
178 | */ | |
179 | if (no_sg_merge) | |
180 | goto new_segment; | |
181 | ||
54efd50b | 182 | if (prev && cluster) { |
7988613b | 183 | if (seg_size + bv.bv_len |
ae03bf63 | 184 | > queue_max_segment_size(q)) |
1e428079 | 185 | goto new_segment; |
7988613b | 186 | if (!BIOVEC_PHYS_MERGEABLE(&bvprv, &bv)) |
1e428079 | 187 | goto new_segment; |
7988613b | 188 | if (!BIOVEC_SEG_BOUNDARY(q, &bvprv, &bv)) |
1e428079 | 189 | goto new_segment; |
d6d48196 | 190 | |
7988613b | 191 | seg_size += bv.bv_len; |
1e428079 JA |
192 | bvprv = bv; |
193 | continue; | |
194 | } | |
d6d48196 | 195 | new_segment: |
1e428079 JA |
196 | if (nr_phys_segs == 1 && seg_size > |
197 | fbio->bi_seg_front_size) | |
198 | fbio->bi_seg_front_size = seg_size; | |
86771427 | 199 | |
1e428079 JA |
200 | nr_phys_segs++; |
201 | bvprv = bv; | |
54efd50b | 202 | prev = 1; |
7988613b | 203 | seg_size = bv.bv_len; |
1e428079 | 204 | } |
59247eae | 205 | bbio = bio; |
d6d48196 JA |
206 | } |
207 | ||
59247eae JA |
208 | if (nr_phys_segs == 1 && seg_size > fbio->bi_seg_front_size) |
209 | fbio->bi_seg_front_size = seg_size; | |
210 | if (seg_size > bbio->bi_seg_back_size) | |
211 | bbio->bi_seg_back_size = seg_size; | |
1e428079 JA |
212 | |
213 | return nr_phys_segs; | |
214 | } | |
215 | ||
216 | void blk_recalc_rq_segments(struct request *rq) | |
217 | { | |
07388549 ML |
218 | bool no_sg_merge = !!test_bit(QUEUE_FLAG_NO_SG_MERGE, |
219 | &rq->q->queue_flags); | |
220 | ||
221 | rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio, | |
222 | no_sg_merge); | |
d6d48196 JA |
223 | } |
224 | ||
225 | void blk_recount_segments(struct request_queue *q, struct bio *bio) | |
226 | { | |
7f60dcaa ML |
227 | unsigned short seg_cnt; |
228 | ||
229 | /* estimate segment number by bi_vcnt for non-cloned bio */ | |
230 | if (bio_flagged(bio, BIO_CLONED)) | |
231 | seg_cnt = bio_segments(bio); | |
232 | else | |
233 | seg_cnt = bio->bi_vcnt; | |
764f612c | 234 | |
7f60dcaa ML |
235 | if (test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags) && |
236 | (seg_cnt < queue_max_segments(q))) | |
237 | bio->bi_phys_segments = seg_cnt; | |
05f1dd53 JA |
238 | else { |
239 | struct bio *nxt = bio->bi_next; | |
240 | ||
241 | bio->bi_next = NULL; | |
7f60dcaa | 242 | bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, false); |
05f1dd53 JA |
243 | bio->bi_next = nxt; |
244 | } | |
1e428079 | 245 | |
b7c44ed9 | 246 | bio_set_flag(bio, BIO_SEG_VALID); |
d6d48196 JA |
247 | } |
248 | EXPORT_SYMBOL(blk_recount_segments); | |
249 | ||
250 | static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio, | |
251 | struct bio *nxt) | |
252 | { | |
2b8221e1 | 253 | struct bio_vec end_bv = { NULL }, nxt_bv; |
f619d254 KO |
254 | struct bvec_iter iter; |
255 | ||
e692cb66 | 256 | if (!blk_queue_cluster(q)) |
d6d48196 JA |
257 | return 0; |
258 | ||
86771427 | 259 | if (bio->bi_seg_back_size + nxt->bi_seg_front_size > |
ae03bf63 | 260 | queue_max_segment_size(q)) |
d6d48196 JA |
261 | return 0; |
262 | ||
e17fc0a1 DW |
263 | if (!bio_has_data(bio)) |
264 | return 1; | |
265 | ||
f619d254 KO |
266 | bio_for_each_segment(end_bv, bio, iter) |
267 | if (end_bv.bv_len == iter.bi_size) | |
268 | break; | |
269 | ||
270 | nxt_bv = bio_iovec(nxt); | |
271 | ||
272 | if (!BIOVEC_PHYS_MERGEABLE(&end_bv, &nxt_bv)) | |
e17fc0a1 DW |
273 | return 0; |
274 | ||
d6d48196 | 275 | /* |
e17fc0a1 | 276 | * bio and nxt are contiguous in memory; check if the queue allows |
d6d48196 JA |
277 | * these two to be merged into one |
278 | */ | |
f619d254 | 279 | if (BIOVEC_SEG_BOUNDARY(q, &end_bv, &nxt_bv)) |
d6d48196 JA |
280 | return 1; |
281 | ||
282 | return 0; | |
283 | } | |
284 | ||
7988613b | 285 | static inline void |
963ab9e5 | 286 | __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, |
7988613b | 287 | struct scatterlist *sglist, struct bio_vec *bvprv, |
963ab9e5 AH |
288 | struct scatterlist **sg, int *nsegs, int *cluster) |
289 | { | |
290 | ||
291 | int nbytes = bvec->bv_len; | |
292 | ||
7988613b | 293 | if (*sg && *cluster) { |
963ab9e5 AH |
294 | if ((*sg)->length + nbytes > queue_max_segment_size(q)) |
295 | goto new_segment; | |
296 | ||
7988613b | 297 | if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) |
963ab9e5 | 298 | goto new_segment; |
7988613b | 299 | if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec)) |
963ab9e5 AH |
300 | goto new_segment; |
301 | ||
302 | (*sg)->length += nbytes; | |
303 | } else { | |
304 | new_segment: | |
305 | if (!*sg) | |
306 | *sg = sglist; | |
307 | else { | |
308 | /* | |
309 | * If the driver previously mapped a shorter | |
310 | * list, we could see a termination bit | |
311 | * prematurely unless it fully inits the sg | |
312 | * table on each mapping. We KNOW that there | |
313 | * must be more entries here or the driver | |
314 | * would be buggy, so force clear the | |
315 | * termination bit to avoid doing a full | |
316 | * sg_init_table() in drivers for each command. | |
317 | */ | |
c8164d89 | 318 | sg_unmark_end(*sg); |
963ab9e5 AH |
319 | *sg = sg_next(*sg); |
320 | } | |
321 | ||
322 | sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); | |
323 | (*nsegs)++; | |
324 | } | |
7988613b | 325 | *bvprv = *bvec; |
963ab9e5 AH |
326 | } |
327 | ||
5cb8850c KO |
328 | static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, |
329 | struct scatterlist *sglist, | |
330 | struct scatterlist **sg) | |
d6d48196 | 331 | { |
2b8221e1 | 332 | struct bio_vec bvec, bvprv = { NULL }; |
5cb8850c | 333 | struct bvec_iter iter; |
d6d48196 JA |
334 | int nsegs, cluster; |
335 | ||
336 | nsegs = 0; | |
e692cb66 | 337 | cluster = blk_queue_cluster(q); |
d6d48196 | 338 | |
5cb8850c KO |
339 | if (bio->bi_rw & REQ_DISCARD) { |
340 | /* | |
341 | * This is a hack - drivers should be neither modifying the | |
342 | * biovec, nor relying on bi_vcnt - but because of | |
343 | * blk_add_request_payload(), a discard bio may or may not have | |
344 | * a payload we need to set up here (thank you Christoph) and | |
345 | * bi_vcnt is really the only way of telling if we need to. | |
346 | */ | |
347 | ||
348 | if (bio->bi_vcnt) | |
349 | goto single_segment; | |
350 | ||
351 | return 0; | |
352 | } | |
353 | ||
354 | if (bio->bi_rw & REQ_WRITE_SAME) { | |
355 | single_segment: | |
356 | *sg = sglist; | |
357 | bvec = bio_iovec(bio); | |
358 | sg_set_page(*sg, bvec.bv_page, bvec.bv_len, bvec.bv_offset); | |
359 | return 1; | |
360 | } | |
361 | ||
362 | for_each_bio(bio) | |
363 | bio_for_each_segment(bvec, bio, iter) | |
364 | __blk_segment_map_sg(q, &bvec, sglist, &bvprv, sg, | |
365 | &nsegs, &cluster); | |
d6d48196 | 366 | |
5cb8850c KO |
367 | return nsegs; |
368 | } | |
369 | ||
370 | /* | |
371 | * map a request to scatterlist, return number of sg entries setup. Caller | |
372 | * must make sure sg can hold rq->nr_phys_segments entries | |
373 | */ | |
374 | int blk_rq_map_sg(struct request_queue *q, struct request *rq, | |
375 | struct scatterlist *sglist) | |
376 | { | |
377 | struct scatterlist *sg = NULL; | |
378 | int nsegs = 0; | |
379 | ||
380 | if (rq->bio) | |
381 | nsegs = __blk_bios_map_sg(q, rq->bio, sglist, &sg); | |
f18573ab FT |
382 | |
383 | if (unlikely(rq->cmd_flags & REQ_COPY_USER) && | |
2e46e8b2 TH |
384 | (blk_rq_bytes(rq) & q->dma_pad_mask)) { |
385 | unsigned int pad_len = | |
386 | (q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1; | |
f18573ab FT |
387 | |
388 | sg->length += pad_len; | |
389 | rq->extra_len += pad_len; | |
390 | } | |
391 | ||
2fb98e84 | 392 | if (q->dma_drain_size && q->dma_drain_needed(rq)) { |
7b6d91da | 393 | if (rq->cmd_flags & REQ_WRITE) |
db0a2e00 TH |
394 | memset(q->dma_drain_buffer, 0, q->dma_drain_size); |
395 | ||
da81ed16 | 396 | sg_unmark_end(sg); |
d6d48196 JA |
397 | sg = sg_next(sg); |
398 | sg_set_page(sg, virt_to_page(q->dma_drain_buffer), | |
399 | q->dma_drain_size, | |
400 | ((unsigned long)q->dma_drain_buffer) & | |
401 | (PAGE_SIZE - 1)); | |
402 | nsegs++; | |
7a85f889 | 403 | rq->extra_len += q->dma_drain_size; |
d6d48196 JA |
404 | } |
405 | ||
406 | if (sg) | |
407 | sg_mark_end(sg); | |
408 | ||
409 | return nsegs; | |
410 | } | |
d6d48196 JA |
411 | EXPORT_SYMBOL(blk_rq_map_sg); |
412 | ||
d6d48196 JA |
413 | static inline int ll_new_hw_segment(struct request_queue *q, |
414 | struct request *req, | |
415 | struct bio *bio) | |
416 | { | |
d6d48196 JA |
417 | int nr_phys_segs = bio_phys_segments(q, bio); |
418 | ||
13f05c8d MP |
419 | if (req->nr_phys_segments + nr_phys_segs > queue_max_segments(q)) |
420 | goto no_merge; | |
421 | ||
4eaf99be | 422 | if (blk_integrity_merge_bio(q, req, bio) == false) |
13f05c8d | 423 | goto no_merge; |
d6d48196 JA |
424 | |
425 | /* | |
426 | * This will form the start of a new hw segment. Bump both | |
427 | * counters. | |
428 | */ | |
d6d48196 JA |
429 | req->nr_phys_segments += nr_phys_segs; |
430 | return 1; | |
13f05c8d MP |
431 | |
432 | no_merge: | |
433 | req->cmd_flags |= REQ_NOMERGE; | |
434 | if (req == q->last_merge) | |
435 | q->last_merge = NULL; | |
436 | return 0; | |
d6d48196 JA |
437 | } |
438 | ||
439 | int ll_back_merge_fn(struct request_queue *q, struct request *req, | |
440 | struct bio *bio) | |
441 | { | |
f31dc1cd MP |
442 | if (blk_rq_sectors(req) + bio_sectors(bio) > |
443 | blk_rq_get_max_sectors(req)) { | |
d6d48196 JA |
444 | req->cmd_flags |= REQ_NOMERGE; |
445 | if (req == q->last_merge) | |
446 | q->last_merge = NULL; | |
447 | return 0; | |
448 | } | |
2cdf79ca | 449 | if (!bio_flagged(req->biotail, BIO_SEG_VALID)) |
d6d48196 | 450 | blk_recount_segments(q, req->biotail); |
2cdf79ca | 451 | if (!bio_flagged(bio, BIO_SEG_VALID)) |
d6d48196 | 452 | blk_recount_segments(q, bio); |
d6d48196 JA |
453 | |
454 | return ll_new_hw_segment(q, req, bio); | |
455 | } | |
456 | ||
6728cb0e | 457 | int ll_front_merge_fn(struct request_queue *q, struct request *req, |
d6d48196 JA |
458 | struct bio *bio) |
459 | { | |
f31dc1cd MP |
460 | if (blk_rq_sectors(req) + bio_sectors(bio) > |
461 | blk_rq_get_max_sectors(req)) { | |
d6d48196 JA |
462 | req->cmd_flags |= REQ_NOMERGE; |
463 | if (req == q->last_merge) | |
464 | q->last_merge = NULL; | |
465 | return 0; | |
466 | } | |
2cdf79ca | 467 | if (!bio_flagged(bio, BIO_SEG_VALID)) |
d6d48196 | 468 | blk_recount_segments(q, bio); |
2cdf79ca | 469 | if (!bio_flagged(req->bio, BIO_SEG_VALID)) |
d6d48196 | 470 | blk_recount_segments(q, req->bio); |
d6d48196 JA |
471 | |
472 | return ll_new_hw_segment(q, req, bio); | |
473 | } | |
474 | ||
e7e24500 JA |
475 | /* |
476 | * blk-mq uses req->special to carry normal driver per-request payload, it | |
477 | * does not indicate a prepared command that we cannot merge with. | |
478 | */ | |
479 | static bool req_no_special_merge(struct request *req) | |
480 | { | |
481 | struct request_queue *q = req->q; | |
482 | ||
483 | return !q->mq_ops && req->special; | |
484 | } | |
485 | ||
03100aad | 486 | static int req_gap_to_prev(struct request *req, struct bio *next) |
854fbb9c KB |
487 | { |
488 | struct bio *prev = req->biotail; | |
489 | ||
03100aad | 490 | return bvec_gap_to_prev(req->q, &prev->bi_io_vec[prev->bi_vcnt - 1], |
2ca495ac | 491 | next->bi_io_vec[0].bv_offset); |
854fbb9c KB |
492 | } |
493 | ||
d6d48196 JA |
494 | static int ll_merge_requests_fn(struct request_queue *q, struct request *req, |
495 | struct request *next) | |
496 | { | |
497 | int total_phys_segments; | |
86771427 FT |
498 | unsigned int seg_size = |
499 | req->biotail->bi_seg_back_size + next->bio->bi_seg_front_size; | |
d6d48196 JA |
500 | |
501 | /* | |
502 | * First check if the either of the requests are re-queued | |
503 | * requests. Can't merge them if they are. | |
504 | */ | |
e7e24500 | 505 | if (req_no_special_merge(req) || req_no_special_merge(next)) |
d6d48196 JA |
506 | return 0; |
507 | ||
03100aad | 508 | if (req_gap_to_prev(req, next->bio)) |
854fbb9c KB |
509 | return 0; |
510 | ||
d6d48196 JA |
511 | /* |
512 | * Will it become too large? | |
513 | */ | |
f31dc1cd MP |
514 | if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > |
515 | blk_rq_get_max_sectors(req)) | |
d6d48196 JA |
516 | return 0; |
517 | ||
518 | total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; | |
86771427 FT |
519 | if (blk_phys_contig_segment(q, req->biotail, next->bio)) { |
520 | if (req->nr_phys_segments == 1) | |
521 | req->bio->bi_seg_front_size = seg_size; | |
522 | if (next->nr_phys_segments == 1) | |
523 | next->biotail->bi_seg_back_size = seg_size; | |
d6d48196 | 524 | total_phys_segments--; |
86771427 | 525 | } |
d6d48196 | 526 | |
8a78362c | 527 | if (total_phys_segments > queue_max_segments(q)) |
d6d48196 JA |
528 | return 0; |
529 | ||
4eaf99be | 530 | if (blk_integrity_merge_rq(q, req, next) == false) |
13f05c8d MP |
531 | return 0; |
532 | ||
d6d48196 JA |
533 | /* Merge is OK... */ |
534 | req->nr_phys_segments = total_phys_segments; | |
d6d48196 JA |
535 | return 1; |
536 | } | |
537 | ||
80a761fd TH |
538 | /** |
539 | * blk_rq_set_mixed_merge - mark a request as mixed merge | |
540 | * @rq: request to mark as mixed merge | |
541 | * | |
542 | * Description: | |
543 | * @rq is about to be mixed merged. Make sure the attributes | |
544 | * which can be mixed are set in each bio and mark @rq as mixed | |
545 | * merged. | |
546 | */ | |
547 | void blk_rq_set_mixed_merge(struct request *rq) | |
548 | { | |
549 | unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; | |
550 | struct bio *bio; | |
551 | ||
552 | if (rq->cmd_flags & REQ_MIXED_MERGE) | |
553 | return; | |
554 | ||
555 | /* | |
556 | * @rq will no longer represent mixable attributes for all the | |
557 | * contained bios. It will just track those of the first one. | |
558 | * Distributes the attributs to each bio. | |
559 | */ | |
560 | for (bio = rq->bio; bio; bio = bio->bi_next) { | |
561 | WARN_ON_ONCE((bio->bi_rw & REQ_FAILFAST_MASK) && | |
562 | (bio->bi_rw & REQ_FAILFAST_MASK) != ff); | |
563 | bio->bi_rw |= ff; | |
564 | } | |
565 | rq->cmd_flags |= REQ_MIXED_MERGE; | |
566 | } | |
567 | ||
26308eab JM |
568 | static void blk_account_io_merge(struct request *req) |
569 | { | |
570 | if (blk_do_io_stat(req)) { | |
571 | struct hd_struct *part; | |
572 | int cpu; | |
573 | ||
574 | cpu = part_stat_lock(); | |
09e099d4 | 575 | part = req->part; |
26308eab JM |
576 | |
577 | part_round_stats(cpu, part); | |
316d315b | 578 | part_dec_in_flight(part, rq_data_dir(req)); |
26308eab | 579 | |
6c23a968 | 580 | hd_struct_put(part); |
26308eab JM |
581 | part_stat_unlock(); |
582 | } | |
583 | } | |
584 | ||
d6d48196 JA |
585 | /* |
586 | * Has to be called with the request spinlock acquired | |
587 | */ | |
588 | static int attempt_merge(struct request_queue *q, struct request *req, | |
589 | struct request *next) | |
590 | { | |
591 | if (!rq_mergeable(req) || !rq_mergeable(next)) | |
592 | return 0; | |
593 | ||
f31dc1cd MP |
594 | if (!blk_check_merge_flags(req->cmd_flags, next->cmd_flags)) |
595 | return 0; | |
596 | ||
d6d48196 JA |
597 | /* |
598 | * not contiguous | |
599 | */ | |
83096ebf | 600 | if (blk_rq_pos(req) + blk_rq_sectors(req) != blk_rq_pos(next)) |
d6d48196 JA |
601 | return 0; |
602 | ||
603 | if (rq_data_dir(req) != rq_data_dir(next) | |
604 | || req->rq_disk != next->rq_disk | |
e7e24500 | 605 | || req_no_special_merge(next)) |
d6d48196 JA |
606 | return 0; |
607 | ||
4363ac7c MP |
608 | if (req->cmd_flags & REQ_WRITE_SAME && |
609 | !blk_write_same_mergeable(req->bio, next->bio)) | |
610 | return 0; | |
611 | ||
d6d48196 JA |
612 | /* |
613 | * If we are allowed to merge, then append bio list | |
614 | * from next to rq and release next. merge_requests_fn | |
615 | * will have updated segment counts, update sector | |
616 | * counts here. | |
617 | */ | |
618 | if (!ll_merge_requests_fn(q, req, next)) | |
619 | return 0; | |
620 | ||
80a761fd TH |
621 | /* |
622 | * If failfast settings disagree or any of the two is already | |
623 | * a mixed merge, mark both as mixed before proceeding. This | |
624 | * makes sure that all involved bios have mixable attributes | |
625 | * set properly. | |
626 | */ | |
627 | if ((req->cmd_flags | next->cmd_flags) & REQ_MIXED_MERGE || | |
628 | (req->cmd_flags & REQ_FAILFAST_MASK) != | |
629 | (next->cmd_flags & REQ_FAILFAST_MASK)) { | |
630 | blk_rq_set_mixed_merge(req); | |
631 | blk_rq_set_mixed_merge(next); | |
632 | } | |
633 | ||
d6d48196 JA |
634 | /* |
635 | * At this point we have either done a back merge | |
636 | * or front merge. We need the smaller start_time of | |
637 | * the merged requests to be the current request | |
638 | * for accounting purposes. | |
639 | */ | |
640 | if (time_after(req->start_time, next->start_time)) | |
641 | req->start_time = next->start_time; | |
642 | ||
643 | req->biotail->bi_next = next->bio; | |
644 | req->biotail = next->biotail; | |
645 | ||
a2dec7b3 | 646 | req->__data_len += blk_rq_bytes(next); |
d6d48196 JA |
647 | |
648 | elv_merge_requests(q, req, next); | |
649 | ||
42dad764 JM |
650 | /* |
651 | * 'next' is going away, so update stats accordingly | |
652 | */ | |
653 | blk_account_io_merge(next); | |
d6d48196 JA |
654 | |
655 | req->ioprio = ioprio_best(req->ioprio, next->ioprio); | |
ab780f1e JA |
656 | if (blk_rq_cpu_valid(next)) |
657 | req->cpu = next->cpu; | |
d6d48196 | 658 | |
1cd96c24 BH |
659 | /* owner-ship of bio passed from next to req */ |
660 | next->bio = NULL; | |
d6d48196 JA |
661 | __blk_put_request(q, next); |
662 | return 1; | |
663 | } | |
664 | ||
665 | int attempt_back_merge(struct request_queue *q, struct request *rq) | |
666 | { | |
667 | struct request *next = elv_latter_request(q, rq); | |
668 | ||
669 | if (next) | |
670 | return attempt_merge(q, rq, next); | |
671 | ||
672 | return 0; | |
673 | } | |
674 | ||
675 | int attempt_front_merge(struct request_queue *q, struct request *rq) | |
676 | { | |
677 | struct request *prev = elv_former_request(q, rq); | |
678 | ||
679 | if (prev) | |
680 | return attempt_merge(q, prev, rq); | |
681 | ||
682 | return 0; | |
683 | } | |
5e84ea3a JA |
684 | |
685 | int blk_attempt_req_merge(struct request_queue *q, struct request *rq, | |
686 | struct request *next) | |
687 | { | |
688 | return attempt_merge(q, rq, next); | |
689 | } | |
050c8ea8 TH |
690 | |
691 | bool blk_rq_merge_ok(struct request *rq, struct bio *bio) | |
692 | { | |
e2a60da7 | 693 | if (!rq_mergeable(rq) || !bio_mergeable(bio)) |
050c8ea8 TH |
694 | return false; |
695 | ||
f31dc1cd MP |
696 | if (!blk_check_merge_flags(rq->cmd_flags, bio->bi_rw)) |
697 | return false; | |
698 | ||
050c8ea8 TH |
699 | /* different data direction or already started, don't merge */ |
700 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
701 | return false; | |
702 | ||
703 | /* must be same device and not a special request */ | |
e7e24500 | 704 | if (rq->rq_disk != bio->bi_bdev->bd_disk || req_no_special_merge(rq)) |
050c8ea8 TH |
705 | return false; |
706 | ||
707 | /* only merge integrity protected bio into ditto rq */ | |
4eaf99be | 708 | if (blk_integrity_merge_bio(rq->q, rq, bio) == false) |
050c8ea8 TH |
709 | return false; |
710 | ||
4363ac7c MP |
711 | /* must be using the same buffer */ |
712 | if (rq->cmd_flags & REQ_WRITE_SAME && | |
713 | !blk_write_same_mergeable(rq->bio, bio)) | |
714 | return false; | |
715 | ||
beefa6ba | 716 | /* Only check gaps if the bio carries data */ |
03100aad KB |
717 | if (bio_has_data(bio) && req_gap_to_prev(rq, bio)) |
718 | return false; | |
66cb45aa | 719 | |
050c8ea8 TH |
720 | return true; |
721 | } | |
722 | ||
723 | int blk_try_merge(struct request *rq, struct bio *bio) | |
724 | { | |
4f024f37 | 725 | if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector) |
050c8ea8 | 726 | return ELEVATOR_BACK_MERGE; |
4f024f37 | 727 | else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector) |
050c8ea8 TH |
728 | return ELEVATOR_FRONT_MERGE; |
729 | return ELEVATOR_NO_MERGE; | |
730 | } |