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