Commit | Line | Data |
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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
d6d48196 JA |
2 | /* |
3 | * Functions related to segment and merge handling | |
4 | */ | |
5 | #include <linux/kernel.h> | |
6 | #include <linux/module.h> | |
7 | #include <linux/bio.h> | |
8 | #include <linux/blkdev.h> | |
fe45e630 | 9 | #include <linux/blk-integrity.h> |
d6d48196 | 10 | #include <linux/scatterlist.h> |
82d981d4 | 11 | #include <linux/part_stat.h> |
6b2b0459 | 12 | #include <linux/blk-cgroup.h> |
d6d48196 | 13 | |
cda22646 MK |
14 | #include <trace/events/block.h> |
15 | ||
d6d48196 | 16 | #include "blk.h" |
2aa7745b | 17 | #include "blk-mq-sched.h" |
8e756373 | 18 | #include "blk-rq-qos.h" |
a7b36ee6 | 19 | #include "blk-throttle.h" |
d6d48196 | 20 | |
ff18d77b CH |
21 | static inline void bio_get_first_bvec(struct bio *bio, struct bio_vec *bv) |
22 | { | |
23 | *bv = mp_bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter); | |
24 | } | |
25 | ||
26 | static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv) | |
27 | { | |
28 | struct bvec_iter iter = bio->bi_iter; | |
29 | int idx; | |
30 | ||
31 | bio_get_first_bvec(bio, bv); | |
32 | if (bv->bv_len == bio->bi_iter.bi_size) | |
33 | return; /* this bio only has a single bvec */ | |
34 | ||
35 | bio_advance_iter(bio, &iter, iter.bi_size); | |
36 | ||
37 | if (!iter.bi_bvec_done) | |
38 | idx = iter.bi_idx - 1; | |
39 | else /* in the middle of bvec */ | |
40 | idx = iter.bi_idx; | |
41 | ||
42 | *bv = bio->bi_io_vec[idx]; | |
43 | ||
44 | /* | |
45 | * iter.bi_bvec_done records actual length of the last bvec | |
46 | * if this bio ends in the middle of one io vector | |
47 | */ | |
48 | if (iter.bi_bvec_done) | |
49 | bv->bv_len = iter.bi_bvec_done; | |
50 | } | |
51 | ||
e9907009 CH |
52 | static inline bool bio_will_gap(struct request_queue *q, |
53 | struct request *prev_rq, struct bio *prev, struct bio *next) | |
54 | { | |
55 | struct bio_vec pb, nb; | |
56 | ||
57 | if (!bio_has_data(prev) || !queue_virt_boundary(q)) | |
58 | return false; | |
59 | ||
60 | /* | |
61 | * Don't merge if the 1st bio starts with non-zero offset, otherwise it | |
62 | * is quite difficult to respect the sg gap limit. We work hard to | |
63 | * merge a huge number of small single bios in case of mkfs. | |
64 | */ | |
65 | if (prev_rq) | |
66 | bio_get_first_bvec(prev_rq->bio, &pb); | |
67 | else | |
68 | bio_get_first_bvec(prev, &pb); | |
df376b2e | 69 | if (pb.bv_offset & queue_virt_boundary(q)) |
e9907009 CH |
70 | return true; |
71 | ||
72 | /* | |
73 | * We don't need to worry about the situation that the merged segment | |
74 | * ends in unaligned virt boundary: | |
75 | * | |
76 | * - if 'pb' ends aligned, the merged segment ends aligned | |
77 | * - if 'pb' ends unaligned, the next bio must include | |
78 | * one single bvec of 'nb', otherwise the 'nb' can't | |
79 | * merge with 'pb' | |
80 | */ | |
81 | bio_get_last_bvec(prev, &pb); | |
82 | bio_get_first_bvec(next, &nb); | |
200a9aff | 83 | if (biovec_phys_mergeable(q, &pb, &nb)) |
e9907009 CH |
84 | return false; |
85 | return __bvec_gap_to_prev(q, &pb, nb.bv_offset); | |
86 | } | |
87 | ||
88 | static inline bool req_gap_back_merge(struct request *req, struct bio *bio) | |
89 | { | |
90 | return bio_will_gap(req->q, req, req->biotail, bio); | |
91 | } | |
92 | ||
93 | static inline bool req_gap_front_merge(struct request *req, struct bio *bio) | |
94 | { | |
95 | return bio_will_gap(req->q, NULL, bio, req->bio); | |
96 | } | |
97 | ||
54efd50b KO |
98 | static struct bio *blk_bio_discard_split(struct request_queue *q, |
99 | struct bio *bio, | |
bdced438 ML |
100 | struct bio_set *bs, |
101 | unsigned *nsegs) | |
54efd50b KO |
102 | { |
103 | unsigned int max_discard_sectors, granularity; | |
104 | int alignment; | |
105 | sector_t tmp; | |
106 | unsigned split_sectors; | |
107 | ||
bdced438 ML |
108 | *nsegs = 1; |
109 | ||
54efd50b KO |
110 | /* Zero-sector (unknown) and one-sector granularities are the same. */ |
111 | granularity = max(q->limits.discard_granularity >> 9, 1U); | |
112 | ||
1adfc5e4 ML |
113 | max_discard_sectors = min(q->limits.max_discard_sectors, |
114 | bio_allowed_max_sectors(q)); | |
54efd50b KO |
115 | max_discard_sectors -= max_discard_sectors % granularity; |
116 | ||
117 | if (unlikely(!max_discard_sectors)) { | |
118 | /* XXX: warn */ | |
119 | return NULL; | |
120 | } | |
121 | ||
122 | if (bio_sectors(bio) <= max_discard_sectors) | |
123 | return NULL; | |
124 | ||
125 | split_sectors = max_discard_sectors; | |
126 | ||
127 | /* | |
128 | * If the next starting sector would be misaligned, stop the discard at | |
129 | * the previous aligned sector. | |
130 | */ | |
131 | alignment = (q->limits.discard_alignment >> 9) % granularity; | |
132 | ||
133 | tmp = bio->bi_iter.bi_sector + split_sectors - alignment; | |
134 | tmp = sector_div(tmp, granularity); | |
135 | ||
136 | if (split_sectors > tmp) | |
137 | split_sectors -= tmp; | |
138 | ||
139 | return bio_split(bio, split_sectors, GFP_NOIO, bs); | |
140 | } | |
141 | ||
885fa13f CH |
142 | static struct bio *blk_bio_write_zeroes_split(struct request_queue *q, |
143 | struct bio *bio, struct bio_set *bs, unsigned *nsegs) | |
144 | { | |
d665e12a | 145 | *nsegs = 0; |
885fa13f CH |
146 | |
147 | if (!q->limits.max_write_zeroes_sectors) | |
148 | return NULL; | |
149 | ||
150 | if (bio_sectors(bio) <= q->limits.max_write_zeroes_sectors) | |
151 | return NULL; | |
152 | ||
153 | return bio_split(bio, q->limits.max_write_zeroes_sectors, GFP_NOIO, bs); | |
154 | } | |
155 | ||
9cc5169c BVA |
156 | /* |
157 | * Return the maximum number of sectors from the start of a bio that may be | |
158 | * submitted as a single request to a block device. If enough sectors remain, | |
159 | * align the end to the physical block size. Otherwise align the end to the | |
160 | * logical block size. This approach minimizes the number of non-aligned | |
161 | * requests that are submitted to a block device if the start of a bio is not | |
162 | * aligned to a physical block boundary. | |
163 | */ | |
d0e5fbb0 ML |
164 | static inline unsigned get_max_io_size(struct request_queue *q, |
165 | struct bio *bio) | |
166 | { | |
9cc5169c BVA |
167 | unsigned pbs = queue_physical_block_size(q) >> SECTOR_SHIFT; |
168 | unsigned lbs = queue_logical_block_size(q) >> SECTOR_SHIFT; | |
efef739d CH |
169 | unsigned max_sectors = queue_max_sectors(q), start, end; |
170 | ||
171 | if (q->limits.chunk_sectors) { | |
172 | max_sectors = min(max_sectors, | |
173 | blk_chunk_sectors_left(bio->bi_iter.bi_sector, | |
174 | q->limits.chunk_sectors)); | |
175 | } | |
84613bed | 176 | |
84613bed CH |
177 | start = bio->bi_iter.bi_sector & (pbs - 1); |
178 | end = (start + max_sectors) & ~(pbs - 1); | |
179 | if (end > start) | |
180 | return end - start; | |
181 | return max_sectors & ~(lbs - 1); | |
d0e5fbb0 ML |
182 | } |
183 | ||
429120f3 ML |
184 | static inline unsigned get_max_segment_size(const struct request_queue *q, |
185 | struct page *start_page, | |
186 | unsigned long offset) | |
dcebd755 ML |
187 | { |
188 | unsigned long mask = queue_segment_boundary(q); | |
189 | ||
429120f3 | 190 | offset = mask & (page_to_phys(start_page) + offset); |
4a2f704e ML |
191 | |
192 | /* | |
193 | * overflow may be triggered in case of zero page physical address | |
194 | * on 32bit arch, use queue's max segment size when that happens. | |
195 | */ | |
196 | return min_not_zero(mask - offset + 1, | |
197 | (unsigned long)queue_max_segment_size(q)); | |
dcebd755 ML |
198 | } |
199 | ||
708b25b3 BVA |
200 | /** |
201 | * bvec_split_segs - verify whether or not a bvec should be split in the middle | |
202 | * @q: [in] request queue associated with the bio associated with @bv | |
203 | * @bv: [in] bvec to examine | |
204 | * @nsegs: [in,out] Number of segments in the bio being built. Incremented | |
205 | * by the number of segments from @bv that may be appended to that | |
206 | * bio without exceeding @max_segs | |
67927d22 KB |
207 | * @bytes: [in,out] Number of bytes in the bio being built. Incremented |
208 | * by the number of bytes from @bv that may be appended to that | |
209 | * bio without exceeding @max_bytes | |
708b25b3 | 210 | * @max_segs: [in] upper bound for *@nsegs |
67927d22 | 211 | * @max_bytes: [in] upper bound for *@bytes |
708b25b3 BVA |
212 | * |
213 | * When splitting a bio, it can happen that a bvec is encountered that is too | |
214 | * big to fit in a single segment and hence that it has to be split in the | |
215 | * middle. This function verifies whether or not that should happen. The value | |
216 | * %true is returned if and only if appending the entire @bv to a bio with | |
217 | * *@nsegs segments and *@sectors sectors would make that bio unacceptable for | |
218 | * the block driver. | |
dcebd755 | 219 | */ |
af2c68fe BVA |
220 | static bool bvec_split_segs(const struct request_queue *q, |
221 | const struct bio_vec *bv, unsigned *nsegs, | |
67927d22 KB |
222 | unsigned *bytes, unsigned max_segs, |
223 | unsigned max_bytes) | |
dcebd755 | 224 | { |
67927d22 | 225 | unsigned max_len = min(max_bytes, UINT_MAX) - *bytes; |
708b25b3 | 226 | unsigned len = min(bv->bv_len, max_len); |
dcebd755 | 227 | unsigned total_len = 0; |
ff9811b3 | 228 | unsigned seg_size = 0; |
dcebd755 | 229 | |
ff9811b3 | 230 | while (len && *nsegs < max_segs) { |
429120f3 ML |
231 | seg_size = get_max_segment_size(q, bv->bv_page, |
232 | bv->bv_offset + total_len); | |
dcebd755 ML |
233 | seg_size = min(seg_size, len); |
234 | ||
ff9811b3 | 235 | (*nsegs)++; |
dcebd755 ML |
236 | total_len += seg_size; |
237 | len -= seg_size; | |
238 | ||
239 | if ((bv->bv_offset + total_len) & queue_virt_boundary(q)) | |
240 | break; | |
241 | } | |
242 | ||
67927d22 | 243 | *bytes += total_len; |
dcebd755 | 244 | |
708b25b3 BVA |
245 | /* tell the caller to split the bvec if it is too big to fit */ |
246 | return len > 0 || bv->bv_len > max_len; | |
dcebd755 ML |
247 | } |
248 | ||
dad77584 BVA |
249 | /** |
250 | * blk_bio_segment_split - split a bio in two bios | |
251 | * @q: [in] request queue pointer | |
252 | * @bio: [in] bio to be split | |
253 | * @bs: [in] bio set to allocate the clone from | |
254 | * @segs: [out] number of segments in the bio with the first half of the sectors | |
255 | * | |
256 | * Clone @bio, update the bi_iter of the clone to represent the first sectors | |
257 | * of @bio and update @bio->bi_iter to represent the remaining sectors. The | |
258 | * following is guaranteed for the cloned bio: | |
259 | * - That it has at most get_max_io_size(@q, @bio) sectors. | |
260 | * - That it has at most queue_max_segments(@q) segments. | |
261 | * | |
262 | * Except for discard requests the cloned bio will point at the bi_io_vec of | |
263 | * the original bio. It is the responsibility of the caller to ensure that the | |
264 | * original bio is not freed before the cloned bio. The caller is also | |
265 | * responsible for ensuring that @bs is only destroyed after processing of the | |
266 | * split bio has finished. | |
267 | */ | |
54efd50b KO |
268 | static struct bio *blk_bio_segment_split(struct request_queue *q, |
269 | struct bio *bio, | |
bdced438 ML |
270 | struct bio_set *bs, |
271 | unsigned *segs) | |
54efd50b | 272 | { |
5014c311 | 273 | struct bio_vec bv, bvprv, *bvprvp = NULL; |
54efd50b | 274 | struct bvec_iter iter; |
67927d22 KB |
275 | unsigned nsegs = 0, bytes = 0; |
276 | const unsigned max_bytes = get_max_io_size(q, bio) << 9; | |
05b700ba | 277 | const unsigned max_segs = queue_max_segments(q); |
54efd50b | 278 | |
dcebd755 | 279 | bio_for_each_bvec(bv, bio, iter) { |
54efd50b KO |
280 | /* |
281 | * If the queue doesn't support SG gaps and adding this | |
282 | * offset would create a gap, disallow it. | |
283 | */ | |
5014c311 | 284 | if (bvprvp && bvec_gap_to_prev(q, bvprvp, bv.bv_offset)) |
54efd50b KO |
285 | goto split; |
286 | ||
708b25b3 | 287 | if (nsegs < max_segs && |
67927d22 | 288 | bytes + bv.bv_len <= max_bytes && |
708b25b3 BVA |
289 | bv.bv_offset + bv.bv_len <= PAGE_SIZE) { |
290 | nsegs++; | |
67927d22 KB |
291 | bytes += bv.bv_len; |
292 | } else if (bvec_split_segs(q, &bv, &nsegs, &bytes, max_segs, | |
293 | max_bytes)) { | |
cf8c0c6a | 294 | goto split; |
e36f6204 KB |
295 | } |
296 | ||
54efd50b | 297 | bvprv = bv; |
578270bf | 298 | bvprvp = &bvprv; |
54efd50b KO |
299 | } |
300 | ||
d627065d CH |
301 | *segs = nsegs; |
302 | return NULL; | |
54efd50b | 303 | split: |
bdced438 | 304 | *segs = nsegs; |
cc29e1bf | 305 | |
67927d22 KB |
306 | /* |
307 | * Individual bvecs might not be logical block aligned. Round down the | |
308 | * split size so that each bio is properly block size aligned, even if | |
309 | * we do not use the full hardware limits. | |
310 | */ | |
311 | bytes = ALIGN_DOWN(bytes, queue_logical_block_size(q)); | |
312 | ||
cc29e1bf JX |
313 | /* |
314 | * Bio splitting may cause subtle trouble such as hang when doing sync | |
315 | * iopoll in direct IO routine. Given performance gain of iopoll for | |
316 | * big IO can be trival, disable iopoll when split needed. | |
317 | */ | |
6ce913fe | 318 | bio_clear_polled(bio); |
67927d22 | 319 | return bio_split(bio, bytes >> SECTOR_SHIFT, GFP_NOIO, bs); |
54efd50b KO |
320 | } |
321 | ||
dad77584 BVA |
322 | /** |
323 | * __blk_queue_split - split a bio and submit the second half | |
abd45c15 | 324 | * @q: [in] request_queue new bio is being queued at |
dad77584 BVA |
325 | * @bio: [in, out] bio to be split |
326 | * @nr_segs: [out] number of segments in the first bio | |
327 | * | |
328 | * Split a bio into two bios, chain the two bios, submit the second half and | |
329 | * store a pointer to the first half in *@bio. If the second bio is still too | |
330 | * big it will be split by a recursive call to this function. Since this | |
309dca30 CH |
331 | * function may allocate a new bio from q->bio_split, it is the responsibility |
332 | * of the caller to ensure that q->bio_split is only released after processing | |
333 | * of the split bio has finished. | |
dad77584 | 334 | */ |
abd45c15 JA |
335 | void __blk_queue_split(struct request_queue *q, struct bio **bio, |
336 | unsigned int *nr_segs) | |
54efd50b | 337 | { |
fa532287 | 338 | struct bio *split = NULL; |
54efd50b | 339 | |
7afafc8a AH |
340 | switch (bio_op(*bio)) { |
341 | case REQ_OP_DISCARD: | |
342 | case REQ_OP_SECURE_ERASE: | |
14ccb66b | 343 | split = blk_bio_discard_split(q, *bio, &q->bio_split, nr_segs); |
7afafc8a | 344 | break; |
a6f0788e | 345 | case REQ_OP_WRITE_ZEROES: |
14ccb66b CH |
346 | split = blk_bio_write_zeroes_split(q, *bio, &q->bio_split, |
347 | nr_segs); | |
a6f0788e | 348 | break; |
7afafc8a | 349 | default: |
14ccb66b | 350 | split = blk_bio_segment_split(q, *bio, &q->bio_split, nr_segs); |
7afafc8a AH |
351 | break; |
352 | } | |
bdced438 | 353 | |
54efd50b | 354 | if (split) { |
6ac45aeb | 355 | /* there isn't chance to merge the splitted bio */ |
1eff9d32 | 356 | split->bi_opf |= REQ_NOMERGE; |
6ac45aeb | 357 | |
54efd50b | 358 | bio_chain(split, *bio); |
eb6f7f7c | 359 | trace_block_split(split, (*bio)->bi_iter.bi_sector); |
ed00aabd | 360 | submit_bio_noacct(*bio); |
54efd50b KO |
361 | *bio = split; |
362 | } | |
363 | } | |
14ccb66b | 364 | |
dad77584 BVA |
365 | /** |
366 | * blk_queue_split - split a bio and submit the second half | |
dad77584 BVA |
367 | * @bio: [in, out] bio to be split |
368 | * | |
369 | * Split a bio into two bios, chains the two bios, submit the second half and | |
370 | * store a pointer to the first half in *@bio. Since this function may allocate | |
309dca30 CH |
371 | * a new bio from q->bio_split, it is the responsibility of the caller to ensure |
372 | * that q->bio_split is only released after processing of the split bio has | |
373 | * finished. | |
dad77584 | 374 | */ |
f695ca38 | 375 | void blk_queue_split(struct bio **bio) |
14ccb66b | 376 | { |
859897c3 | 377 | struct request_queue *q = bdev_get_queue((*bio)->bi_bdev); |
14ccb66b CH |
378 | unsigned int nr_segs; |
379 | ||
abd45c15 JA |
380 | if (blk_may_split(q, *bio)) |
381 | __blk_queue_split(q, bio, &nr_segs); | |
14ccb66b | 382 | } |
54efd50b KO |
383 | EXPORT_SYMBOL(blk_queue_split); |
384 | ||
e9cd19c0 | 385 | unsigned int blk_recalc_rq_segments(struct request *rq) |
d6d48196 | 386 | { |
6869875f | 387 | unsigned int nr_phys_segs = 0; |
67927d22 | 388 | unsigned int bytes = 0; |
e9cd19c0 | 389 | struct req_iterator iter; |
6869875f | 390 | struct bio_vec bv; |
d6d48196 | 391 | |
e9cd19c0 | 392 | if (!rq->bio) |
1e428079 | 393 | return 0; |
d6d48196 | 394 | |
e9cd19c0 | 395 | switch (bio_op(rq->bio)) { |
a6f0788e CK |
396 | case REQ_OP_DISCARD: |
397 | case REQ_OP_SECURE_ERASE: | |
a958937f DJ |
398 | if (queue_max_discard_segments(rq->q) > 1) { |
399 | struct bio *bio = rq->bio; | |
400 | ||
401 | for_each_bio(bio) | |
402 | nr_phys_segs++; | |
403 | return nr_phys_segs; | |
404 | } | |
405 | return 1; | |
a6f0788e | 406 | case REQ_OP_WRITE_ZEROES: |
f9d03f96 | 407 | return 0; |
a6f0788e | 408 | } |
5cb8850c | 409 | |
e9cd19c0 | 410 | rq_for_each_bvec(bv, rq, iter) |
67927d22 | 411 | bvec_split_segs(rq->q, &bv, &nr_phys_segs, &bytes, |
708b25b3 | 412 | UINT_MAX, UINT_MAX); |
1e428079 JA |
413 | return nr_phys_segs; |
414 | } | |
415 | ||
48d7727c | 416 | static inline struct scatterlist *blk_next_sg(struct scatterlist **sg, |
862e5a5e ML |
417 | struct scatterlist *sglist) |
418 | { | |
419 | if (!*sg) | |
420 | return sglist; | |
421 | ||
422 | /* | |
423 | * If the driver previously mapped a shorter list, we could see a | |
424 | * termination bit prematurely unless it fully inits the sg table | |
425 | * on each mapping. We KNOW that there must be more entries here | |
426 | * or the driver would be buggy, so force clear the termination bit | |
427 | * to avoid doing a full sg_init_table() in drivers for each command. | |
428 | */ | |
429 | sg_unmark_end(*sg); | |
430 | return sg_next(*sg); | |
431 | } | |
432 | ||
433 | static unsigned blk_bvec_map_sg(struct request_queue *q, | |
434 | struct bio_vec *bvec, struct scatterlist *sglist, | |
435 | struct scatterlist **sg) | |
436 | { | |
437 | unsigned nbytes = bvec->bv_len; | |
8a96a0e4 | 438 | unsigned nsegs = 0, total = 0; |
862e5a5e ML |
439 | |
440 | while (nbytes > 0) { | |
8a96a0e4 | 441 | unsigned offset = bvec->bv_offset + total; |
429120f3 ML |
442 | unsigned len = min(get_max_segment_size(q, bvec->bv_page, |
443 | offset), nbytes); | |
f9f76879 CH |
444 | struct page *page = bvec->bv_page; |
445 | ||
446 | /* | |
447 | * Unfortunately a fair number of drivers barf on scatterlists | |
448 | * that have an offset larger than PAGE_SIZE, despite other | |
449 | * subsystems dealing with that invariant just fine. For now | |
450 | * stick to the legacy format where we never present those from | |
451 | * the block layer, but the code below should be removed once | |
452 | * these offenders (mostly MMC/SD drivers) are fixed. | |
453 | */ | |
454 | page += (offset >> PAGE_SHIFT); | |
455 | offset &= ~PAGE_MASK; | |
862e5a5e ML |
456 | |
457 | *sg = blk_next_sg(sg, sglist); | |
f9f76879 | 458 | sg_set_page(*sg, page, len, offset); |
862e5a5e | 459 | |
8a96a0e4 CH |
460 | total += len; |
461 | nbytes -= len; | |
862e5a5e ML |
462 | nsegs++; |
463 | } | |
464 | ||
465 | return nsegs; | |
466 | } | |
467 | ||
16e3e418 ML |
468 | static inline int __blk_bvec_map_sg(struct bio_vec bv, |
469 | struct scatterlist *sglist, struct scatterlist **sg) | |
470 | { | |
471 | *sg = blk_next_sg(sg, sglist); | |
472 | sg_set_page(*sg, bv.bv_page, bv.bv_len, bv.bv_offset); | |
473 | return 1; | |
474 | } | |
475 | ||
f6970f83 ML |
476 | /* only try to merge bvecs into one sg if they are from two bios */ |
477 | static inline bool | |
478 | __blk_segment_map_sg_merge(struct request_queue *q, struct bio_vec *bvec, | |
479 | struct bio_vec *bvprv, struct scatterlist **sg) | |
963ab9e5 AH |
480 | { |
481 | ||
482 | int nbytes = bvec->bv_len; | |
483 | ||
f6970f83 ML |
484 | if (!*sg) |
485 | return false; | |
963ab9e5 | 486 | |
f6970f83 ML |
487 | if ((*sg)->length + nbytes > queue_max_segment_size(q)) |
488 | return false; | |
489 | ||
490 | if (!biovec_phys_mergeable(q, bvprv, bvec)) | |
491 | return false; | |
492 | ||
493 | (*sg)->length += nbytes; | |
494 | ||
495 | return true; | |
963ab9e5 AH |
496 | } |
497 | ||
5cb8850c KO |
498 | static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, |
499 | struct scatterlist *sglist, | |
500 | struct scatterlist **sg) | |
d6d48196 | 501 | { |
3f649ab7 | 502 | struct bio_vec bvec, bvprv = { NULL }; |
5cb8850c | 503 | struct bvec_iter iter; |
38417468 | 504 | int nsegs = 0; |
f6970f83 | 505 | bool new_bio = false; |
5cb8850c | 506 | |
f6970f83 ML |
507 | for_each_bio(bio) { |
508 | bio_for_each_bvec(bvec, bio, iter) { | |
509 | /* | |
510 | * Only try to merge bvecs from two bios given we | |
511 | * have done bio internal merge when adding pages | |
512 | * to bio | |
513 | */ | |
514 | if (new_bio && | |
515 | __blk_segment_map_sg_merge(q, &bvec, &bvprv, sg)) | |
516 | goto next_bvec; | |
517 | ||
518 | if (bvec.bv_offset + bvec.bv_len <= PAGE_SIZE) | |
519 | nsegs += __blk_bvec_map_sg(bvec, sglist, sg); | |
520 | else | |
521 | nsegs += blk_bvec_map_sg(q, &bvec, sglist, sg); | |
522 | next_bvec: | |
523 | new_bio = false; | |
524 | } | |
b21e11c5 ML |
525 | if (likely(bio->bi_iter.bi_size)) { |
526 | bvprv = bvec; | |
527 | new_bio = true; | |
528 | } | |
f6970f83 | 529 | } |
d6d48196 | 530 | |
5cb8850c KO |
531 | return nsegs; |
532 | } | |
533 | ||
534 | /* | |
535 | * map a request to scatterlist, return number of sg entries setup. Caller | |
536 | * must make sure sg can hold rq->nr_phys_segments entries | |
537 | */ | |
89de1504 CH |
538 | int __blk_rq_map_sg(struct request_queue *q, struct request *rq, |
539 | struct scatterlist *sglist, struct scatterlist **last_sg) | |
5cb8850c | 540 | { |
5cb8850c KO |
541 | int nsegs = 0; |
542 | ||
f9d03f96 | 543 | if (rq->rq_flags & RQF_SPECIAL_PAYLOAD) |
89de1504 | 544 | nsegs = __blk_bvec_map_sg(rq->special_vec, sglist, last_sg); |
f9d03f96 | 545 | else if (rq->bio) |
89de1504 | 546 | nsegs = __blk_bios_map_sg(q, rq->bio, sglist, last_sg); |
f18573ab | 547 | |
89de1504 CH |
548 | if (*last_sg) |
549 | sg_mark_end(*last_sg); | |
d6d48196 | 550 | |
12e57f59 ML |
551 | /* |
552 | * Something must have been wrong if the figured number of | |
553 | * segment is bigger than number of req's physical segments | |
554 | */ | |
f9d03f96 | 555 | WARN_ON(nsegs > blk_rq_nr_phys_segments(rq)); |
12e57f59 | 556 | |
d6d48196 JA |
557 | return nsegs; |
558 | } | |
89de1504 | 559 | EXPORT_SYMBOL(__blk_rq_map_sg); |
d6d48196 | 560 | |
943b40c8 ML |
561 | static inline unsigned int blk_rq_get_max_segments(struct request *rq) |
562 | { | |
563 | if (req_op(rq) == REQ_OP_DISCARD) | |
564 | return queue_max_discard_segments(rq->q); | |
565 | return queue_max_segments(rq->q); | |
566 | } | |
567 | ||
badf7f64 CH |
568 | static inline unsigned int blk_rq_get_max_sectors(struct request *rq, |
569 | sector_t offset) | |
570 | { | |
571 | struct request_queue *q = rq->q; | |
c8875190 | 572 | unsigned int max_sectors; |
badf7f64 CH |
573 | |
574 | if (blk_rq_is_passthrough(rq)) | |
575 | return q->limits.max_hw_sectors; | |
576 | ||
c8875190 | 577 | max_sectors = blk_queue_get_max_sectors(q, req_op(rq)); |
badf7f64 CH |
578 | if (!q->limits.chunk_sectors || |
579 | req_op(rq) == REQ_OP_DISCARD || | |
580 | req_op(rq) == REQ_OP_SECURE_ERASE) | |
c8875190 CH |
581 | return max_sectors; |
582 | return min(max_sectors, | |
583 | blk_chunk_sectors_left(offset, q->limits.chunk_sectors)); | |
badf7f64 CH |
584 | } |
585 | ||
14ccb66b CH |
586 | static inline int ll_new_hw_segment(struct request *req, struct bio *bio, |
587 | unsigned int nr_phys_segs) | |
d6d48196 | 588 | { |
6b2b0459 TH |
589 | if (!blk_cgroup_mergeable(req, bio)) |
590 | goto no_merge; | |
591 | ||
2705dfb2 | 592 | if (blk_integrity_merge_bio(req->q, req, bio) == false) |
13f05c8d MP |
593 | goto no_merge; |
594 | ||
2705dfb2 ML |
595 | /* discard request merge won't add new segment */ |
596 | if (req_op(req) == REQ_OP_DISCARD) | |
597 | return 1; | |
598 | ||
599 | if (req->nr_phys_segments + nr_phys_segs > blk_rq_get_max_segments(req)) | |
13f05c8d | 600 | goto no_merge; |
d6d48196 JA |
601 | |
602 | /* | |
603 | * This will form the start of a new hw segment. Bump both | |
604 | * counters. | |
605 | */ | |
d6d48196 JA |
606 | req->nr_phys_segments += nr_phys_segs; |
607 | return 1; | |
13f05c8d MP |
608 | |
609 | no_merge: | |
14ccb66b | 610 | req_set_nomerge(req->q, req); |
13f05c8d | 611 | return 0; |
d6d48196 JA |
612 | } |
613 | ||
14ccb66b | 614 | int ll_back_merge_fn(struct request *req, struct bio *bio, unsigned int nr_segs) |
d6d48196 | 615 | { |
5e7c4274 JA |
616 | if (req_gap_back_merge(req, bio)) |
617 | return 0; | |
7f39add3 SG |
618 | if (blk_integrity_rq(req) && |
619 | integrity_req_gap_back_merge(req, bio)) | |
620 | return 0; | |
a892c8d5 ST |
621 | if (!bio_crypt_ctx_back_mergeable(req, bio)) |
622 | return 0; | |
f31dc1cd | 623 | if (blk_rq_sectors(req) + bio_sectors(bio) > |
17007f39 | 624 | blk_rq_get_max_sectors(req, blk_rq_pos(req))) { |
14ccb66b | 625 | req_set_nomerge(req->q, req); |
d6d48196 JA |
626 | return 0; |
627 | } | |
d6d48196 | 628 | |
14ccb66b | 629 | return ll_new_hw_segment(req, bio, nr_segs); |
d6d48196 JA |
630 | } |
631 | ||
eda5cc99 CH |
632 | static int ll_front_merge_fn(struct request *req, struct bio *bio, |
633 | unsigned int nr_segs) | |
d6d48196 | 634 | { |
5e7c4274 JA |
635 | if (req_gap_front_merge(req, bio)) |
636 | return 0; | |
7f39add3 SG |
637 | if (blk_integrity_rq(req) && |
638 | integrity_req_gap_front_merge(req, bio)) | |
639 | return 0; | |
a892c8d5 ST |
640 | if (!bio_crypt_ctx_front_mergeable(req, bio)) |
641 | return 0; | |
f31dc1cd | 642 | if (blk_rq_sectors(req) + bio_sectors(bio) > |
17007f39 | 643 | blk_rq_get_max_sectors(req, bio->bi_iter.bi_sector)) { |
14ccb66b | 644 | req_set_nomerge(req->q, req); |
d6d48196 JA |
645 | return 0; |
646 | } | |
d6d48196 | 647 | |
14ccb66b | 648 | return ll_new_hw_segment(req, bio, nr_segs); |
d6d48196 JA |
649 | } |
650 | ||
445251d0 JA |
651 | static bool req_attempt_discard_merge(struct request_queue *q, struct request *req, |
652 | struct request *next) | |
653 | { | |
654 | unsigned short segments = blk_rq_nr_discard_segments(req); | |
655 | ||
656 | if (segments >= queue_max_discard_segments(q)) | |
657 | goto no_merge; | |
658 | if (blk_rq_sectors(req) + bio_sectors(next->bio) > | |
659 | blk_rq_get_max_sectors(req, blk_rq_pos(req))) | |
660 | goto no_merge; | |
661 | ||
662 | req->nr_phys_segments = segments + blk_rq_nr_discard_segments(next); | |
663 | return true; | |
664 | no_merge: | |
665 | req_set_nomerge(q, req); | |
666 | return false; | |
667 | } | |
668 | ||
d6d48196 JA |
669 | static int ll_merge_requests_fn(struct request_queue *q, struct request *req, |
670 | struct request *next) | |
671 | { | |
672 | int total_phys_segments; | |
d6d48196 | 673 | |
5e7c4274 | 674 | if (req_gap_back_merge(req, next->bio)) |
854fbb9c KB |
675 | return 0; |
676 | ||
d6d48196 JA |
677 | /* |
678 | * Will it become too large? | |
679 | */ | |
f31dc1cd | 680 | if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > |
17007f39 | 681 | blk_rq_get_max_sectors(req, blk_rq_pos(req))) |
d6d48196 JA |
682 | return 0; |
683 | ||
684 | total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; | |
943b40c8 | 685 | if (total_phys_segments > blk_rq_get_max_segments(req)) |
d6d48196 JA |
686 | return 0; |
687 | ||
6b2b0459 TH |
688 | if (!blk_cgroup_mergeable(req, next->bio)) |
689 | return 0; | |
690 | ||
4eaf99be | 691 | if (blk_integrity_merge_rq(q, req, next) == false) |
13f05c8d MP |
692 | return 0; |
693 | ||
a892c8d5 ST |
694 | if (!bio_crypt_ctx_merge_rq(req, next)) |
695 | return 0; | |
696 | ||
d6d48196 JA |
697 | /* Merge is OK... */ |
698 | req->nr_phys_segments = total_phys_segments; | |
d6d48196 JA |
699 | return 1; |
700 | } | |
701 | ||
80a761fd TH |
702 | /** |
703 | * blk_rq_set_mixed_merge - mark a request as mixed merge | |
704 | * @rq: request to mark as mixed merge | |
705 | * | |
706 | * Description: | |
707 | * @rq is about to be mixed merged. Make sure the attributes | |
708 | * which can be mixed are set in each bio and mark @rq as mixed | |
709 | * merged. | |
710 | */ | |
711 | void blk_rq_set_mixed_merge(struct request *rq) | |
712 | { | |
713 | unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; | |
714 | struct bio *bio; | |
715 | ||
e8064021 | 716 | if (rq->rq_flags & RQF_MIXED_MERGE) |
80a761fd TH |
717 | return; |
718 | ||
719 | /* | |
720 | * @rq will no longer represent mixable attributes for all the | |
721 | * contained bios. It will just track those of the first one. | |
722 | * Distributes the attributs to each bio. | |
723 | */ | |
724 | for (bio = rq->bio; bio; bio = bio->bi_next) { | |
1eff9d32 JA |
725 | WARN_ON_ONCE((bio->bi_opf & REQ_FAILFAST_MASK) && |
726 | (bio->bi_opf & REQ_FAILFAST_MASK) != ff); | |
727 | bio->bi_opf |= ff; | |
80a761fd | 728 | } |
e8064021 | 729 | rq->rq_flags |= RQF_MIXED_MERGE; |
80a761fd TH |
730 | } |
731 | ||
b9c54f56 | 732 | static void blk_account_io_merge_request(struct request *req) |
26308eab JM |
733 | { |
734 | if (blk_do_io_stat(req)) { | |
112f158f | 735 | part_stat_lock(); |
b9c54f56 | 736 | part_stat_inc(req->part, merges[op_stat_group(req_op(req))]); |
26308eab JM |
737 | part_stat_unlock(); |
738 | } | |
739 | } | |
b9c54f56 | 740 | |
e96c0d83 EB |
741 | static enum elv_merge blk_try_req_merge(struct request *req, |
742 | struct request *next) | |
69840466 JW |
743 | { |
744 | if (blk_discard_mergable(req)) | |
745 | return ELEVATOR_DISCARD_MERGE; | |
746 | else if (blk_rq_pos(req) + blk_rq_sectors(req) == blk_rq_pos(next)) | |
747 | return ELEVATOR_BACK_MERGE; | |
748 | ||
749 | return ELEVATOR_NO_MERGE; | |
750 | } | |
26308eab | 751 | |
d6d48196 | 752 | /* |
b973cb7e JA |
753 | * For non-mq, this has to be called with the request spinlock acquired. |
754 | * For mq with scheduling, the appropriate queue wide lock should be held. | |
d6d48196 | 755 | */ |
b973cb7e JA |
756 | static struct request *attempt_merge(struct request_queue *q, |
757 | struct request *req, struct request *next) | |
d6d48196 JA |
758 | { |
759 | if (!rq_mergeable(req) || !rq_mergeable(next)) | |
b973cb7e | 760 | return NULL; |
d6d48196 | 761 | |
288dab8a | 762 | if (req_op(req) != req_op(next)) |
b973cb7e | 763 | return NULL; |
f31dc1cd | 764 | |
79bb1dbd | 765 | if (rq_data_dir(req) != rq_data_dir(next)) |
b973cb7e | 766 | return NULL; |
d6d48196 | 767 | |
668ffc03 DLM |
768 | if (req->ioprio != next->ioprio) |
769 | return NULL; | |
770 | ||
d6d48196 JA |
771 | /* |
772 | * If we are allowed to merge, then append bio list | |
773 | * from next to rq and release next. merge_requests_fn | |
774 | * will have updated segment counts, update sector | |
445251d0 JA |
775 | * counts here. Handle DISCARDs separately, as they |
776 | * have separate settings. | |
d6d48196 | 777 | */ |
69840466 JW |
778 | |
779 | switch (blk_try_req_merge(req, next)) { | |
780 | case ELEVATOR_DISCARD_MERGE: | |
445251d0 JA |
781 | if (!req_attempt_discard_merge(q, req, next)) |
782 | return NULL; | |
69840466 JW |
783 | break; |
784 | case ELEVATOR_BACK_MERGE: | |
785 | if (!ll_merge_requests_fn(q, req, next)) | |
786 | return NULL; | |
787 | break; | |
788 | default: | |
b973cb7e | 789 | return NULL; |
69840466 | 790 | } |
d6d48196 | 791 | |
80a761fd TH |
792 | /* |
793 | * If failfast settings disagree or any of the two is already | |
794 | * a mixed merge, mark both as mixed before proceeding. This | |
795 | * makes sure that all involved bios have mixable attributes | |
796 | * set properly. | |
797 | */ | |
e8064021 | 798 | if (((req->rq_flags | next->rq_flags) & RQF_MIXED_MERGE) || |
80a761fd TH |
799 | (req->cmd_flags & REQ_FAILFAST_MASK) != |
800 | (next->cmd_flags & REQ_FAILFAST_MASK)) { | |
801 | blk_rq_set_mixed_merge(req); | |
802 | blk_rq_set_mixed_merge(next); | |
803 | } | |
804 | ||
d6d48196 | 805 | /* |
522a7775 OS |
806 | * At this point we have either done a back merge or front merge. We |
807 | * need the smaller start_time_ns of the merged requests to be the | |
808 | * current request for accounting purposes. | |
d6d48196 | 809 | */ |
522a7775 OS |
810 | if (next->start_time_ns < req->start_time_ns) |
811 | req->start_time_ns = next->start_time_ns; | |
d6d48196 JA |
812 | |
813 | req->biotail->bi_next = next->bio; | |
814 | req->biotail = next->biotail; | |
815 | ||
a2dec7b3 | 816 | req->__data_len += blk_rq_bytes(next); |
d6d48196 | 817 | |
2a5cf35c | 818 | if (!blk_discard_mergable(req)) |
445251d0 | 819 | elv_merge_requests(q, req, next); |
d6d48196 | 820 | |
42dad764 JM |
821 | /* |
822 | * 'next' is going away, so update stats accordingly | |
823 | */ | |
b9c54f56 | 824 | blk_account_io_merge_request(next); |
d6d48196 | 825 | |
a54895fa | 826 | trace_block_rq_merge(next); |
f3bdc62f | 827 | |
e4d750c9 JA |
828 | /* |
829 | * ownership of bio passed from next to req, return 'next' for | |
830 | * the caller to free | |
831 | */ | |
1cd96c24 | 832 | next->bio = NULL; |
b973cb7e | 833 | return next; |
d6d48196 JA |
834 | } |
835 | ||
eda5cc99 CH |
836 | static struct request *attempt_back_merge(struct request_queue *q, |
837 | struct request *rq) | |
d6d48196 JA |
838 | { |
839 | struct request *next = elv_latter_request(q, rq); | |
840 | ||
841 | if (next) | |
842 | return attempt_merge(q, rq, next); | |
843 | ||
b973cb7e | 844 | return NULL; |
d6d48196 JA |
845 | } |
846 | ||
eda5cc99 CH |
847 | static struct request *attempt_front_merge(struct request_queue *q, |
848 | struct request *rq) | |
d6d48196 JA |
849 | { |
850 | struct request *prev = elv_former_request(q, rq); | |
851 | ||
852 | if (prev) | |
853 | return attempt_merge(q, prev, rq); | |
854 | ||
b973cb7e | 855 | return NULL; |
d6d48196 | 856 | } |
5e84ea3a | 857 | |
fd2ef39c JK |
858 | /* |
859 | * Try to merge 'next' into 'rq'. Return true if the merge happened, false | |
860 | * otherwise. The caller is responsible for freeing 'next' if the merge | |
861 | * happened. | |
862 | */ | |
863 | bool blk_attempt_req_merge(struct request_queue *q, struct request *rq, | |
864 | struct request *next) | |
5e84ea3a | 865 | { |
fd2ef39c | 866 | return attempt_merge(q, rq, next); |
5e84ea3a | 867 | } |
050c8ea8 TH |
868 | |
869 | bool blk_rq_merge_ok(struct request *rq, struct bio *bio) | |
870 | { | |
e2a60da7 | 871 | if (!rq_mergeable(rq) || !bio_mergeable(bio)) |
050c8ea8 TH |
872 | return false; |
873 | ||
288dab8a | 874 | if (req_op(rq) != bio_op(bio)) |
f31dc1cd MP |
875 | return false; |
876 | ||
050c8ea8 TH |
877 | /* different data direction or already started, don't merge */ |
878 | if (bio_data_dir(bio) != rq_data_dir(rq)) | |
879 | return false; | |
880 | ||
6b2b0459 TH |
881 | /* don't merge across cgroup boundaries */ |
882 | if (!blk_cgroup_mergeable(rq, bio)) | |
883 | return false; | |
884 | ||
050c8ea8 | 885 | /* only merge integrity protected bio into ditto rq */ |
4eaf99be | 886 | if (blk_integrity_merge_bio(rq->q, rq, bio) == false) |
050c8ea8 TH |
887 | return false; |
888 | ||
a892c8d5 ST |
889 | /* Only merge if the crypt contexts are compatible */ |
890 | if (!bio_crypt_rq_ctx_compatible(rq, bio)) | |
891 | return false; | |
892 | ||
668ffc03 DLM |
893 | if (rq->ioprio != bio_prio(bio)) |
894 | return false; | |
895 | ||
050c8ea8 TH |
896 | return true; |
897 | } | |
898 | ||
34fe7c05 | 899 | enum elv_merge blk_try_merge(struct request *rq, struct bio *bio) |
050c8ea8 | 900 | { |
69840466 | 901 | if (blk_discard_mergable(rq)) |
1e739730 CH |
902 | return ELEVATOR_DISCARD_MERGE; |
903 | else if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector) | |
050c8ea8 | 904 | return ELEVATOR_BACK_MERGE; |
4f024f37 | 905 | else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector) |
050c8ea8 TH |
906 | return ELEVATOR_FRONT_MERGE; |
907 | return ELEVATOR_NO_MERGE; | |
908 | } | |
8e756373 BW |
909 | |
910 | static void blk_account_io_merge_bio(struct request *req) | |
911 | { | |
912 | if (!blk_do_io_stat(req)) | |
913 | return; | |
914 | ||
915 | part_stat_lock(); | |
916 | part_stat_inc(req->part, merges[op_stat_group(req_op(req))]); | |
917 | part_stat_unlock(); | |
918 | } | |
919 | ||
eda5cc99 CH |
920 | enum bio_merge_status { |
921 | BIO_MERGE_OK, | |
922 | BIO_MERGE_NONE, | |
923 | BIO_MERGE_FAILED, | |
924 | }; | |
925 | ||
926 | static enum bio_merge_status bio_attempt_back_merge(struct request *req, | |
927 | struct bio *bio, unsigned int nr_segs) | |
8e756373 BW |
928 | { |
929 | const int ff = bio->bi_opf & REQ_FAILFAST_MASK; | |
930 | ||
931 | if (!ll_back_merge_fn(req, bio, nr_segs)) | |
7d7ca7c5 | 932 | return BIO_MERGE_FAILED; |
8e756373 | 933 | |
e8a676d6 | 934 | trace_block_bio_backmerge(bio); |
8e756373 BW |
935 | rq_qos_merge(req->q, req, bio); |
936 | ||
937 | if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) | |
938 | blk_rq_set_mixed_merge(req); | |
939 | ||
940 | req->biotail->bi_next = bio; | |
941 | req->biotail = bio; | |
942 | req->__data_len += bio->bi_iter.bi_size; | |
943 | ||
944 | bio_crypt_free_ctx(bio); | |
945 | ||
946 | blk_account_io_merge_bio(req); | |
7d7ca7c5 | 947 | return BIO_MERGE_OK; |
8e756373 BW |
948 | } |
949 | ||
eda5cc99 CH |
950 | static enum bio_merge_status bio_attempt_front_merge(struct request *req, |
951 | struct bio *bio, unsigned int nr_segs) | |
8e756373 BW |
952 | { |
953 | const int ff = bio->bi_opf & REQ_FAILFAST_MASK; | |
954 | ||
955 | if (!ll_front_merge_fn(req, bio, nr_segs)) | |
7d7ca7c5 | 956 | return BIO_MERGE_FAILED; |
8e756373 | 957 | |
e8a676d6 | 958 | trace_block_bio_frontmerge(bio); |
8e756373 BW |
959 | rq_qos_merge(req->q, req, bio); |
960 | ||
961 | if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) | |
962 | blk_rq_set_mixed_merge(req); | |
963 | ||
964 | bio->bi_next = req->bio; | |
965 | req->bio = bio; | |
966 | ||
967 | req->__sector = bio->bi_iter.bi_sector; | |
968 | req->__data_len += bio->bi_iter.bi_size; | |
969 | ||
970 | bio_crypt_do_front_merge(req, bio); | |
971 | ||
972 | blk_account_io_merge_bio(req); | |
7d7ca7c5 | 973 | return BIO_MERGE_OK; |
8e756373 BW |
974 | } |
975 | ||
eda5cc99 CH |
976 | static enum bio_merge_status bio_attempt_discard_merge(struct request_queue *q, |
977 | struct request *req, struct bio *bio) | |
8e756373 BW |
978 | { |
979 | unsigned short segments = blk_rq_nr_discard_segments(req); | |
980 | ||
981 | if (segments >= queue_max_discard_segments(q)) | |
982 | goto no_merge; | |
983 | if (blk_rq_sectors(req) + bio_sectors(bio) > | |
984 | blk_rq_get_max_sectors(req, blk_rq_pos(req))) | |
985 | goto no_merge; | |
986 | ||
987 | rq_qos_merge(q, req, bio); | |
988 | ||
989 | req->biotail->bi_next = bio; | |
990 | req->biotail = bio; | |
991 | req->__data_len += bio->bi_iter.bi_size; | |
992 | req->nr_phys_segments = segments + 1; | |
993 | ||
994 | blk_account_io_merge_bio(req); | |
7d7ca7c5 | 995 | return BIO_MERGE_OK; |
8e756373 BW |
996 | no_merge: |
997 | req_set_nomerge(q, req); | |
7d7ca7c5 BW |
998 | return BIO_MERGE_FAILED; |
999 | } | |
1000 | ||
1001 | static enum bio_merge_status blk_attempt_bio_merge(struct request_queue *q, | |
1002 | struct request *rq, | |
1003 | struct bio *bio, | |
1004 | unsigned int nr_segs, | |
1005 | bool sched_allow_merge) | |
1006 | { | |
1007 | if (!blk_rq_merge_ok(rq, bio)) | |
1008 | return BIO_MERGE_NONE; | |
1009 | ||
1010 | switch (blk_try_merge(rq, bio)) { | |
1011 | case ELEVATOR_BACK_MERGE: | |
265600b7 | 1012 | if (!sched_allow_merge || blk_mq_sched_allow_merge(q, rq, bio)) |
7d7ca7c5 BW |
1013 | return bio_attempt_back_merge(rq, bio, nr_segs); |
1014 | break; | |
1015 | case ELEVATOR_FRONT_MERGE: | |
265600b7 | 1016 | if (!sched_allow_merge || blk_mq_sched_allow_merge(q, rq, bio)) |
7d7ca7c5 BW |
1017 | return bio_attempt_front_merge(rq, bio, nr_segs); |
1018 | break; | |
1019 | case ELEVATOR_DISCARD_MERGE: | |
1020 | return bio_attempt_discard_merge(q, rq, bio); | |
1021 | default: | |
1022 | return BIO_MERGE_NONE; | |
1023 | } | |
1024 | ||
1025 | return BIO_MERGE_FAILED; | |
8e756373 BW |
1026 | } |
1027 | ||
1028 | /** | |
1029 | * blk_attempt_plug_merge - try to merge with %current's plugged list | |
1030 | * @q: request_queue new bio is being queued at | |
1031 | * @bio: new bio being queued | |
1032 | * @nr_segs: number of segments in @bio | |
87c037d1 | 1033 | * from the passed in @q already in the plug list |
8e756373 | 1034 | * |
d38a9c04 JA |
1035 | * Determine whether @bio being queued on @q can be merged with the previous |
1036 | * request on %current's plugged list. Returns %true if merge was successful, | |
8e756373 BW |
1037 | * otherwise %false. |
1038 | * | |
1039 | * Plugging coalesces IOs from the same issuer for the same purpose without | |
1040 | * going through @q->queue_lock. As such it's more of an issuing mechanism | |
1041 | * than scheduling, and the request, while may have elvpriv data, is not | |
1042 | * added on the elevator at this point. In addition, we don't have | |
1043 | * reliable access to the elevator outside queue lock. Only check basic | |
1044 | * merging parameters without querying the elevator. | |
1045 | * | |
1046 | * Caller must ensure !blk_queue_nomerges(q) beforehand. | |
1047 | */ | |
1048 | bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio, | |
0c5bcc92 | 1049 | unsigned int nr_segs) |
8e756373 BW |
1050 | { |
1051 | struct blk_plug *plug; | |
1052 | struct request *rq; | |
8e756373 | 1053 | |
6deacb3b | 1054 | plug = blk_mq_plug(bio); |
bc490f81 | 1055 | if (!plug || rq_list_empty(plug->mq_list)) |
8e756373 BW |
1056 | return false; |
1057 | ||
5b205071 JA |
1058 | rq_list_for_each(&plug->mq_list, rq) { |
1059 | if (rq->q == q) { | |
1060 | if (blk_attempt_bio_merge(q, rq, bio, nr_segs, false) == | |
1061 | BIO_MERGE_OK) | |
1062 | return true; | |
1063 | break; | |
1064 | } | |
1065 | ||
1066 | /* | |
1067 | * Only keep iterating plug list for merges if we have multiple | |
1068 | * queues | |
1069 | */ | |
1070 | if (!plug->multiple_queues) | |
1071 | break; | |
8e756373 | 1072 | } |
8e756373 BW |
1073 | return false; |
1074 | } | |
bdc6a287 BW |
1075 | |
1076 | /* | |
1077 | * Iterate list of requests and see if we can merge this bio with any | |
1078 | * of them. | |
1079 | */ | |
1080 | bool blk_bio_list_merge(struct request_queue *q, struct list_head *list, | |
1081 | struct bio *bio, unsigned int nr_segs) | |
1082 | { | |
1083 | struct request *rq; | |
1084 | int checked = 8; | |
1085 | ||
1086 | list_for_each_entry_reverse(rq, list, queuelist) { | |
bdc6a287 BW |
1087 | if (!checked--) |
1088 | break; | |
1089 | ||
7d7ca7c5 BW |
1090 | switch (blk_attempt_bio_merge(q, rq, bio, nr_segs, true)) { |
1091 | case BIO_MERGE_NONE: | |
bdc6a287 | 1092 | continue; |
7d7ca7c5 BW |
1093 | case BIO_MERGE_OK: |
1094 | return true; | |
1095 | case BIO_MERGE_FAILED: | |
1096 | return false; | |
bdc6a287 BW |
1097 | } |
1098 | ||
bdc6a287 BW |
1099 | } |
1100 | ||
1101 | return false; | |
1102 | } | |
1103 | EXPORT_SYMBOL_GPL(blk_bio_list_merge); | |
eda5cc99 CH |
1104 | |
1105 | bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio, | |
1106 | unsigned int nr_segs, struct request **merged_request) | |
1107 | { | |
1108 | struct request *rq; | |
1109 | ||
1110 | switch (elv_merge(q, &rq, bio)) { | |
1111 | case ELEVATOR_BACK_MERGE: | |
1112 | if (!blk_mq_sched_allow_merge(q, rq, bio)) | |
1113 | return false; | |
1114 | if (bio_attempt_back_merge(rq, bio, nr_segs) != BIO_MERGE_OK) | |
1115 | return false; | |
1116 | *merged_request = attempt_back_merge(q, rq); | |
1117 | if (!*merged_request) | |
1118 | elv_merged_request(q, rq, ELEVATOR_BACK_MERGE); | |
1119 | return true; | |
1120 | case ELEVATOR_FRONT_MERGE: | |
1121 | if (!blk_mq_sched_allow_merge(q, rq, bio)) | |
1122 | return false; | |
1123 | if (bio_attempt_front_merge(rq, bio, nr_segs) != BIO_MERGE_OK) | |
1124 | return false; | |
1125 | *merged_request = attempt_front_merge(q, rq); | |
1126 | if (!*merged_request) | |
1127 | elv_merged_request(q, rq, ELEVATOR_FRONT_MERGE); | |
1128 | return true; | |
1129 | case ELEVATOR_DISCARD_MERGE: | |
1130 | return bio_attempt_discard_merge(q, rq, bio) == BIO_MERGE_OK; | |
1131 | default: | |
1132 | return false; | |
1133 | } | |
1134 | } | |
1135 | EXPORT_SYMBOL_GPL(blk_mq_sched_try_merge); |