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