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 | ||
1e428079 | 12 | static unsigned int __blk_recalc_rq_segments(struct request_queue *q, |
07388549 ML |
13 | struct bio *bio, |
14 | bool no_sg_merge) | |
d6d48196 | 15 | { |
7988613b | 16 | struct bio_vec bv, bvprv = { NULL }; |
07388549 | 17 | int cluster, high, highprv = 1; |
1e428079 | 18 | unsigned int seg_size, nr_phys_segs; |
59247eae | 19 | struct bio *fbio, *bbio; |
7988613b | 20 | struct bvec_iter iter; |
d6d48196 | 21 | |
1e428079 JA |
22 | if (!bio) |
23 | return 0; | |
d6d48196 | 24 | |
5cb8850c KO |
25 | /* |
26 | * This should probably be returning 0, but blk_add_request_payload() | |
27 | * (Christoph!!!!) | |
28 | */ | |
29 | if (bio->bi_rw & REQ_DISCARD) | |
30 | return 1; | |
31 | ||
32 | if (bio->bi_rw & REQ_WRITE_SAME) | |
33 | return 1; | |
34 | ||
1e428079 | 35 | fbio = bio; |
e692cb66 | 36 | cluster = blk_queue_cluster(q); |
5df97b91 | 37 | seg_size = 0; |
2c8919de | 38 | nr_phys_segs = 0; |
05f1dd53 | 39 | high = 0; |
1e428079 | 40 | for_each_bio(bio) { |
7988613b | 41 | bio_for_each_segment(bv, bio, iter) { |
05f1dd53 JA |
42 | /* |
43 | * If SG merging is disabled, each bio vector is | |
44 | * a segment | |
45 | */ | |
46 | if (no_sg_merge) | |
47 | goto new_segment; | |
48 | ||
1e428079 JA |
49 | /* |
50 | * the trick here is making sure that a high page is | |
05f1dd53 JA |
51 | * never considered part of another segment, since |
52 | * that might change with the bounce page. | |
1e428079 | 53 | */ |
7988613b KO |
54 | high = page_to_pfn(bv.bv_page) > queue_bounce_pfn(q); |
55 | if (!high && !highprv && cluster) { | |
56 | if (seg_size + bv.bv_len | |
ae03bf63 | 57 | > queue_max_segment_size(q)) |
1e428079 | 58 | goto new_segment; |
7988613b | 59 | if (!BIOVEC_PHYS_MERGEABLE(&bvprv, &bv)) |
1e428079 | 60 | goto new_segment; |
7988613b | 61 | if (!BIOVEC_SEG_BOUNDARY(q, &bvprv, &bv)) |
1e428079 | 62 | goto new_segment; |
d6d48196 | 63 | |
7988613b | 64 | seg_size += bv.bv_len; |
1e428079 JA |
65 | bvprv = bv; |
66 | continue; | |
67 | } | |
d6d48196 | 68 | new_segment: |
1e428079 JA |
69 | if (nr_phys_segs == 1 && seg_size > |
70 | fbio->bi_seg_front_size) | |
71 | fbio->bi_seg_front_size = seg_size; | |
86771427 | 72 | |
1e428079 JA |
73 | nr_phys_segs++; |
74 | bvprv = bv; | |
7988613b | 75 | seg_size = bv.bv_len; |
1e428079 JA |
76 | highprv = high; |
77 | } | |
59247eae | 78 | bbio = bio; |
d6d48196 JA |
79 | } |
80 | ||
59247eae JA |
81 | if (nr_phys_segs == 1 && seg_size > fbio->bi_seg_front_size) |
82 | fbio->bi_seg_front_size = seg_size; | |
83 | if (seg_size > bbio->bi_seg_back_size) | |
84 | bbio->bi_seg_back_size = seg_size; | |
1e428079 JA |
85 | |
86 | return nr_phys_segs; | |
87 | } | |
88 | ||
89 | void blk_recalc_rq_segments(struct request *rq) | |
90 | { | |
07388549 ML |
91 | bool no_sg_merge = !!test_bit(QUEUE_FLAG_NO_SG_MERGE, |
92 | &rq->q->queue_flags); | |
93 | ||
94 | rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio, | |
95 | no_sg_merge); | |
d6d48196 JA |
96 | } |
97 | ||
98 | void blk_recount_segments(struct request_queue *q, struct bio *bio) | |
99 | { | |
7f60dcaa ML |
100 | unsigned short seg_cnt; |
101 | ||
102 | /* estimate segment number by bi_vcnt for non-cloned bio */ | |
103 | if (bio_flagged(bio, BIO_CLONED)) | |
104 | seg_cnt = bio_segments(bio); | |
105 | else | |
106 | seg_cnt = bio->bi_vcnt; | |
764f612c | 107 | |
7f60dcaa ML |
108 | if (test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags) && |
109 | (seg_cnt < queue_max_segments(q))) | |
110 | bio->bi_phys_segments = seg_cnt; | |
05f1dd53 JA |
111 | else { |
112 | struct bio *nxt = bio->bi_next; | |
113 | ||
114 | bio->bi_next = NULL; | |
7f60dcaa | 115 | bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, false); |
05f1dd53 JA |
116 | bio->bi_next = nxt; |
117 | } | |
1e428079 | 118 | |
d6d48196 JA |
119 | bio->bi_flags |= (1 << BIO_SEG_VALID); |
120 | } | |
121 | EXPORT_SYMBOL(blk_recount_segments); | |
122 | ||
123 | static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio, | |
124 | struct bio *nxt) | |
125 | { | |
2b8221e1 | 126 | struct bio_vec end_bv = { NULL }, nxt_bv; |
f619d254 KO |
127 | struct bvec_iter iter; |
128 | ||
e692cb66 | 129 | if (!blk_queue_cluster(q)) |
d6d48196 JA |
130 | return 0; |
131 | ||
86771427 | 132 | if (bio->bi_seg_back_size + nxt->bi_seg_front_size > |
ae03bf63 | 133 | queue_max_segment_size(q)) |
d6d48196 JA |
134 | return 0; |
135 | ||
e17fc0a1 DW |
136 | if (!bio_has_data(bio)) |
137 | return 1; | |
138 | ||
f619d254 KO |
139 | bio_for_each_segment(end_bv, bio, iter) |
140 | if (end_bv.bv_len == iter.bi_size) | |
141 | break; | |
142 | ||
143 | nxt_bv = bio_iovec(nxt); | |
144 | ||
145 | if (!BIOVEC_PHYS_MERGEABLE(&end_bv, &nxt_bv)) | |
e17fc0a1 DW |
146 | return 0; |
147 | ||
d6d48196 | 148 | /* |
e17fc0a1 | 149 | * bio and nxt are contiguous in memory; check if the queue allows |
d6d48196 JA |
150 | * these two to be merged into one |
151 | */ | |
f619d254 | 152 | if (BIOVEC_SEG_BOUNDARY(q, &end_bv, &nxt_bv)) |
d6d48196 JA |
153 | return 1; |
154 | ||
155 | return 0; | |
156 | } | |
157 | ||
7988613b | 158 | static inline void |
963ab9e5 | 159 | __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, |
7988613b | 160 | struct scatterlist *sglist, struct bio_vec *bvprv, |
963ab9e5 AH |
161 | struct scatterlist **sg, int *nsegs, int *cluster) |
162 | { | |
163 | ||
164 | int nbytes = bvec->bv_len; | |
165 | ||
7988613b | 166 | if (*sg && *cluster) { |
963ab9e5 AH |
167 | if ((*sg)->length + nbytes > queue_max_segment_size(q)) |
168 | goto new_segment; | |
169 | ||
7988613b | 170 | if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) |
963ab9e5 | 171 | goto new_segment; |
7988613b | 172 | if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec)) |
963ab9e5 AH |
173 | goto new_segment; |
174 | ||
175 | (*sg)->length += nbytes; | |
176 | } else { | |
177 | new_segment: | |
178 | if (!*sg) | |
179 | *sg = sglist; | |
180 | else { | |
181 | /* | |
182 | * If the driver previously mapped a shorter | |
183 | * list, we could see a termination bit | |
184 | * prematurely unless it fully inits the sg | |
185 | * table on each mapping. We KNOW that there | |
186 | * must be more entries here or the driver | |
187 | * would be buggy, so force clear the | |
188 | * termination bit to avoid doing a full | |
189 | * sg_init_table() in drivers for each command. | |
190 | */ | |
c8164d89 | 191 | sg_unmark_end(*sg); |
963ab9e5 AH |
192 | *sg = sg_next(*sg); |
193 | } | |
194 | ||
195 | sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); | |
196 | (*nsegs)++; | |
197 | } | |
7988613b | 198 | *bvprv = *bvec; |
963ab9e5 AH |
199 | } |
200 | ||
5cb8850c KO |
201 | static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, |
202 | struct scatterlist *sglist, | |
203 | struct scatterlist **sg) | |
d6d48196 | 204 | { |
2b8221e1 | 205 | struct bio_vec bvec, bvprv = { NULL }; |
5cb8850c | 206 | struct bvec_iter iter; |
d6d48196 JA |
207 | int nsegs, cluster; |
208 | ||
209 | nsegs = 0; | |
e692cb66 | 210 | cluster = blk_queue_cluster(q); |
d6d48196 | 211 | |
5cb8850c KO |
212 | if (bio->bi_rw & REQ_DISCARD) { |
213 | /* | |
214 | * This is a hack - drivers should be neither modifying the | |
215 | * biovec, nor relying on bi_vcnt - but because of | |
216 | * blk_add_request_payload(), a discard bio may or may not have | |
217 | * a payload we need to set up here (thank you Christoph) and | |
218 | * bi_vcnt is really the only way of telling if we need to. | |
219 | */ | |
220 | ||
221 | if (bio->bi_vcnt) | |
222 | goto single_segment; | |
223 | ||
224 | return 0; | |
225 | } | |
226 | ||
227 | if (bio->bi_rw & REQ_WRITE_SAME) { | |
228 | single_segment: | |
229 | *sg = sglist; | |
230 | bvec = bio_iovec(bio); | |
231 | sg_set_page(*sg, bvec.bv_page, bvec.bv_len, bvec.bv_offset); | |
232 | return 1; | |
233 | } | |
234 | ||
235 | for_each_bio(bio) | |
236 | bio_for_each_segment(bvec, bio, iter) | |
237 | __blk_segment_map_sg(q, &bvec, sglist, &bvprv, sg, | |
238 | &nsegs, &cluster); | |
d6d48196 | 239 | |
5cb8850c KO |
240 | return nsegs; |
241 | } | |
242 | ||
243 | /* | |
244 | * map a request to scatterlist, return number of sg entries setup. Caller | |
245 | * must make sure sg can hold rq->nr_phys_segments entries | |
246 | */ | |
247 | int blk_rq_map_sg(struct request_queue *q, struct request *rq, | |
248 | struct scatterlist *sglist) | |
249 | { | |
250 | struct scatterlist *sg = NULL; | |
251 | int nsegs = 0; | |
252 | ||
253 | if (rq->bio) | |
254 | nsegs = __blk_bios_map_sg(q, rq->bio, sglist, &sg); | |
f18573ab FT |
255 | |
256 | if (unlikely(rq->cmd_flags & REQ_COPY_USER) && | |
2e46e8b2 TH |
257 | (blk_rq_bytes(rq) & q->dma_pad_mask)) { |
258 | unsigned int pad_len = | |
259 | (q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1; | |
f18573ab FT |
260 | |
261 | sg->length += pad_len; | |
262 | rq->extra_len += pad_len; | |
263 | } | |
264 | ||
2fb98e84 | 265 | if (q->dma_drain_size && q->dma_drain_needed(rq)) { |
7b6d91da | 266 | if (rq->cmd_flags & REQ_WRITE) |
db0a2e00 TH |
267 | memset(q->dma_drain_buffer, 0, q->dma_drain_size); |
268 | ||
d6d48196 JA |
269 | sg->page_link &= ~0x02; |
270 | sg = sg_next(sg); | |
271 | sg_set_page(sg, virt_to_page(q->dma_drain_buffer), | |
272 | q->dma_drain_size, | |
273 | ((unsigned long)q->dma_drain_buffer) & | |
274 | (PAGE_SIZE - 1)); | |
275 | nsegs++; | |
7a85f889 | 276 | rq->extra_len += q->dma_drain_size; |
d6d48196 JA |
277 | } |
278 | ||
279 | if (sg) | |
280 | sg_mark_end(sg); | |
281 | ||
282 | return nsegs; | |
283 | } | |
d6d48196 JA |
284 | EXPORT_SYMBOL(blk_rq_map_sg); |
285 | ||
85b9f66a AH |
286 | /** |
287 | * blk_bio_map_sg - map a bio to a scatterlist | |
288 | * @q: request_queue in question | |
289 | * @bio: bio being mapped | |
290 | * @sglist: scatterlist being mapped | |
291 | * | |
292 | * Note: | |
293 | * Caller must make sure sg can hold bio->bi_phys_segments entries | |
294 | * | |
295 | * Will return the number of sg entries setup | |
296 | */ | |
297 | int blk_bio_map_sg(struct request_queue *q, struct bio *bio, | |
298 | struct scatterlist *sglist) | |
299 | { | |
5cb8850c KO |
300 | struct scatterlist *sg = NULL; |
301 | int nsegs; | |
302 | struct bio *next = bio->bi_next; | |
303 | bio->bi_next = NULL; | |
85b9f66a | 304 | |
5cb8850c KO |
305 | nsegs = __blk_bios_map_sg(q, bio, sglist, &sg); |
306 | bio->bi_next = next; | |
85b9f66a AH |
307 | if (sg) |
308 | sg_mark_end(sg); | |
309 | ||
310 | BUG_ON(bio->bi_phys_segments && nsegs > bio->bi_phys_segments); | |
311 | return nsegs; | |
312 | } | |
313 | EXPORT_SYMBOL(blk_bio_map_sg); | |
314 | ||
d6d48196 JA |
315 | static inline int ll_new_hw_segment(struct request_queue *q, |
316 | struct request *req, | |
317 | struct bio *bio) | |
318 | { | |
d6d48196 JA |
319 | int nr_phys_segs = bio_phys_segments(q, bio); |
320 | ||
13f05c8d MP |
321 | if (req->nr_phys_segments + nr_phys_segs > queue_max_segments(q)) |
322 | goto no_merge; | |
323 | ||
4eaf99be | 324 | if (blk_integrity_merge_bio(q, req, bio) == false) |
13f05c8d | 325 | goto no_merge; |
d6d48196 JA |
326 | |
327 | /* | |
328 | * This will form the start of a new hw segment. Bump both | |
329 | * counters. | |
330 | */ | |
d6d48196 JA |
331 | req->nr_phys_segments += nr_phys_segs; |
332 | return 1; | |
13f05c8d MP |
333 | |
334 | no_merge: | |
335 | req->cmd_flags |= REQ_NOMERGE; | |
336 | if (req == q->last_merge) | |
337 | q->last_merge = NULL; | |
338 | return 0; | |
d6d48196 JA |
339 | } |
340 | ||
341 | int ll_back_merge_fn(struct request_queue *q, struct request *req, | |
342 | struct bio *bio) | |
343 | { | |
f31dc1cd MP |
344 | if (blk_rq_sectors(req) + bio_sectors(bio) > |
345 | blk_rq_get_max_sectors(req)) { | |
d6d48196 JA |
346 | req->cmd_flags |= REQ_NOMERGE; |
347 | if (req == q->last_merge) | |
348 | q->last_merge = NULL; | |
349 | return 0; | |
350 | } | |
2cdf79ca | 351 | if (!bio_flagged(req->biotail, BIO_SEG_VALID)) |
d6d48196 | 352 | blk_recount_segments(q, req->biotail); |
2cdf79ca | 353 | if (!bio_flagged(bio, BIO_SEG_VALID)) |
d6d48196 | 354 | blk_recount_segments(q, bio); |
d6d48196 JA |
355 | |
356 | return ll_new_hw_segment(q, req, bio); | |
357 | } | |
358 | ||
6728cb0e | 359 | int ll_front_merge_fn(struct request_queue *q, struct request *req, |
d6d48196 JA |
360 | struct bio *bio) |
361 | { | |
f31dc1cd MP |
362 | if (blk_rq_sectors(req) + bio_sectors(bio) > |
363 | blk_rq_get_max_sectors(req)) { | |
d6d48196 JA |
364 | req->cmd_flags |= REQ_NOMERGE; |
365 | if (req == q->last_merge) | |
366 | q->last_merge = NULL; | |
367 | return 0; | |
368 | } | |
2cdf79ca | 369 | if (!bio_flagged(bio, BIO_SEG_VALID)) |
d6d48196 | 370 | blk_recount_segments(q, bio); |
2cdf79ca | 371 | if (!bio_flagged(req->bio, BIO_SEG_VALID)) |
d6d48196 | 372 | blk_recount_segments(q, req->bio); |
d6d48196 JA |
373 | |
374 | return ll_new_hw_segment(q, req, bio); | |
375 | } | |
376 | ||
e7e24500 JA |
377 | /* |
378 | * blk-mq uses req->special to carry normal driver per-request payload, it | |
379 | * does not indicate a prepared command that we cannot merge with. | |
380 | */ | |
381 | static bool req_no_special_merge(struct request *req) | |
382 | { | |
383 | struct request_queue *q = req->q; | |
384 | ||
385 | return !q->mq_ops && req->special; | |
386 | } | |
387 | ||
d6d48196 JA |
388 | static int ll_merge_requests_fn(struct request_queue *q, struct request *req, |
389 | struct request *next) | |
390 | { | |
391 | int total_phys_segments; | |
86771427 FT |
392 | unsigned int seg_size = |
393 | req->biotail->bi_seg_back_size + next->bio->bi_seg_front_size; | |
d6d48196 JA |
394 | |
395 | /* | |
396 | * First check if the either of the requests are re-queued | |
397 | * requests. Can't merge them if they are. | |
398 | */ | |
e7e24500 | 399 | if (req_no_special_merge(req) || req_no_special_merge(next)) |
d6d48196 JA |
400 | return 0; |
401 | ||
402 | /* | |
403 | * Will it become too large? | |
404 | */ | |
f31dc1cd MP |
405 | if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > |
406 | blk_rq_get_max_sectors(req)) | |
d6d48196 JA |
407 | return 0; |
408 | ||
409 | total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; | |
86771427 FT |
410 | if (blk_phys_contig_segment(q, req->biotail, next->bio)) { |
411 | if (req->nr_phys_segments == 1) | |
412 | req->bio->bi_seg_front_size = seg_size; | |
413 | if (next->nr_phys_segments == 1) | |
414 | next->biotail->bi_seg_back_size = seg_size; | |
d6d48196 | 415 | total_phys_segments--; |
86771427 | 416 | } |
d6d48196 | 417 | |
8a78362c | 418 | if (total_phys_segments > queue_max_segments(q)) |
d6d48196 JA |
419 | return 0; |
420 | ||
4eaf99be | 421 | if (blk_integrity_merge_rq(q, req, next) == false) |
13f05c8d MP |
422 | return 0; |
423 | ||
d6d48196 JA |
424 | /* Merge is OK... */ |
425 | req->nr_phys_segments = total_phys_segments; | |
d6d48196 JA |
426 | return 1; |
427 | } | |
428 | ||
80a761fd TH |
429 | /** |
430 | * blk_rq_set_mixed_merge - mark a request as mixed merge | |
431 | * @rq: request to mark as mixed merge | |
432 | * | |
433 | * Description: | |
434 | * @rq is about to be mixed merged. Make sure the attributes | |
435 | * which can be mixed are set in each bio and mark @rq as mixed | |
436 | * merged. | |
437 | */ | |
438 | void blk_rq_set_mixed_merge(struct request *rq) | |
439 | { | |
440 | unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; | |
441 | struct bio *bio; | |
442 | ||
443 | if (rq->cmd_flags & REQ_MIXED_MERGE) | |
444 | return; | |
445 | ||
446 | /* | |
447 | * @rq will no longer represent mixable attributes for all the | |
448 | * contained bios. It will just track those of the first one. | |
449 | * Distributes the attributs to each bio. | |
450 | */ | |
451 | for (bio = rq->bio; bio; bio = bio->bi_next) { | |
452 | WARN_ON_ONCE((bio->bi_rw & REQ_FAILFAST_MASK) && | |
453 | (bio->bi_rw & REQ_FAILFAST_MASK) != ff); | |
454 | bio->bi_rw |= ff; | |
455 | } | |
456 | rq->cmd_flags |= REQ_MIXED_MERGE; | |
457 | } | |
458 | ||
26308eab JM |
459 | static void blk_account_io_merge(struct request *req) |
460 | { | |
461 | if (blk_do_io_stat(req)) { | |
462 | struct hd_struct *part; | |
463 | int cpu; | |
464 | ||
465 | cpu = part_stat_lock(); | |
09e099d4 | 466 | part = req->part; |
26308eab JM |
467 | |
468 | part_round_stats(cpu, part); | |
316d315b | 469 | part_dec_in_flight(part, rq_data_dir(req)); |
26308eab | 470 | |
6c23a968 | 471 | hd_struct_put(part); |
26308eab JM |
472 | part_stat_unlock(); |
473 | } | |
474 | } | |
475 | ||
d6d48196 JA |
476 | /* |
477 | * Has to be called with the request spinlock acquired | |
478 | */ | |
479 | static int attempt_merge(struct request_queue *q, struct request *req, | |
480 | struct request *next) | |
481 | { | |
482 | if (!rq_mergeable(req) || !rq_mergeable(next)) | |
483 | return 0; | |
484 | ||
f31dc1cd MP |
485 | if (!blk_check_merge_flags(req->cmd_flags, next->cmd_flags)) |
486 | return 0; | |
487 | ||
d6d48196 JA |
488 | /* |
489 | * not contiguous | |
490 | */ | |
83096ebf | 491 | if (blk_rq_pos(req) + blk_rq_sectors(req) != blk_rq_pos(next)) |
d6d48196 JA |
492 | return 0; |
493 | ||
494 | if (rq_data_dir(req) != rq_data_dir(next) | |
495 | || req->rq_disk != next->rq_disk | |
e7e24500 | 496 | || req_no_special_merge(next)) |
d6d48196 JA |
497 | return 0; |
498 | ||
4363ac7c MP |
499 | if (req->cmd_flags & REQ_WRITE_SAME && |
500 | !blk_write_same_mergeable(req->bio, next->bio)) | |
501 | return 0; | |
502 | ||
d6d48196 JA |
503 | /* |
504 | * If we are allowed to merge, then append bio list | |
505 | * from next to rq and release next. merge_requests_fn | |
506 | * will have updated segment counts, update sector | |
507 | * counts here. | |
508 | */ | |
509 | if (!ll_merge_requests_fn(q, req, next)) | |
510 | return 0; | |
511 | ||
80a761fd TH |
512 | /* |
513 | * If failfast settings disagree or any of the two is already | |
514 | * a mixed merge, mark both as mixed before proceeding. This | |
515 | * makes sure that all involved bios have mixable attributes | |
516 | * set properly. | |
517 | */ | |
518 | if ((req->cmd_flags | next->cmd_flags) & REQ_MIXED_MERGE || | |
519 | (req->cmd_flags & REQ_FAILFAST_MASK) != | |
520 | (next->cmd_flags & REQ_FAILFAST_MASK)) { | |
521 | blk_rq_set_mixed_merge(req); | |
522 | blk_rq_set_mixed_merge(next); | |
523 | } | |
524 | ||
d6d48196 JA |
525 | /* |
526 | * At this point we have either done a back merge | |
527 | * or front merge. We need the smaller start_time of | |
528 | * the merged requests to be the current request | |
529 | * for accounting purposes. | |
530 | */ | |
531 | if (time_after(req->start_time, next->start_time)) | |
532 | req->start_time = next->start_time; | |
533 | ||
534 | req->biotail->bi_next = next->bio; | |
535 | req->biotail = next->biotail; | |
536 | ||
a2dec7b3 | 537 | req->__data_len += blk_rq_bytes(next); |
d6d48196 JA |
538 | |
539 | elv_merge_requests(q, req, next); | |
540 | ||
42dad764 JM |
541 | /* |
542 | * 'next' is going away, so update stats accordingly | |
543 | */ | |
544 | blk_account_io_merge(next); | |
d6d48196 JA |
545 | |
546 | req->ioprio = ioprio_best(req->ioprio, next->ioprio); | |
ab780f1e JA |
547 | if (blk_rq_cpu_valid(next)) |
548 | req->cpu = next->cpu; | |
d6d48196 | 549 | |
1cd96c24 BH |
550 | /* owner-ship of bio passed from next to req */ |
551 | next->bio = NULL; | |
d6d48196 JA |
552 | __blk_put_request(q, next); |
553 | return 1; | |
554 | } | |
555 | ||
556 | int attempt_back_merge(struct request_queue *q, struct request *rq) | |
557 | { | |
558 | struct request *next = elv_latter_request(q, rq); | |
559 | ||
560 | if (next) | |
561 | return attempt_merge(q, rq, next); | |
562 | ||
563 | return 0; | |
564 | } | |
565 | ||
566 | int attempt_front_merge(struct request_queue *q, struct request *rq) | |
567 | { | |
568 | struct request *prev = elv_former_request(q, rq); | |
569 | ||
570 | if (prev) | |
571 | return attempt_merge(q, prev, rq); | |
572 | ||
573 | return 0; | |
574 | } | |
5e84ea3a JA |
575 | |
576 | int blk_attempt_req_merge(struct request_queue *q, struct request *rq, | |
577 | struct request *next) | |
578 | { | |
579 | return attempt_merge(q, rq, next); | |
580 | } | |
050c8ea8 TH |
581 | |
582 | bool blk_rq_merge_ok(struct request *rq, struct bio *bio) | |
583 | { | |
66cb45aa JA |
584 | struct request_queue *q = rq->q; |
585 | ||
e2a60da7 | 586 | if (!rq_mergeable(rq) || !bio_mergeable(bio)) |
050c8ea8 TH |
587 | return false; |
588 | ||
f31dc1cd MP |
589 | if (!blk_check_merge_flags(rq->cmd_flags, bio->bi_rw)) |
590 | return false; | |
591 | ||
050c8ea8 TH |
592 | /* different data direction or already started, don't merge */ |
593 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
594 | return false; | |
595 | ||
596 | /* must be same device and not a special request */ | |
e7e24500 | 597 | if (rq->rq_disk != bio->bi_bdev->bd_disk || req_no_special_merge(rq)) |
050c8ea8 TH |
598 | return false; |
599 | ||
600 | /* only merge integrity protected bio into ditto rq */ | |
4eaf99be | 601 | if (blk_integrity_merge_bio(rq->q, rq, bio) == false) |
050c8ea8 TH |
602 | return false; |
603 | ||
4363ac7c MP |
604 | /* must be using the same buffer */ |
605 | if (rq->cmd_flags & REQ_WRITE_SAME && | |
606 | !blk_write_same_mergeable(rq->bio, bio)) | |
607 | return false; | |
608 | ||
66cb45aa JA |
609 | if (q->queue_flags & (1 << QUEUE_FLAG_SG_GAPS)) { |
610 | struct bio_vec *bprev; | |
611 | ||
612 | bprev = &rq->biotail->bi_io_vec[bio->bi_vcnt - 1]; | |
613 | if (bvec_gap_to_prev(bprev, bio->bi_io_vec[0].bv_offset)) | |
614 | return false; | |
615 | } | |
616 | ||
050c8ea8 TH |
617 | return true; |
618 | } | |
619 | ||
620 | int blk_try_merge(struct request *rq, struct bio *bio) | |
621 | { | |
4f024f37 | 622 | if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector) |
050c8ea8 | 623 | return ELEVATOR_BACK_MERGE; |
4f024f37 | 624 | else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector) |
050c8ea8 TH |
625 | return ELEVATOR_FRONT_MERGE; |
626 | return ELEVATOR_NO_MERGE; | |
627 | } |