Branch data Line data Source code
1 : : // SPDX-License-Identifier: GPL-2.0
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>
9 : : #include <linux/scatterlist.h>
10 : :
11 : : #include <trace/events/block.h>
12 : :
13 : : #include "blk.h"
14 : :
15 : 2614740 : static inline bool bio_will_gap(struct request_queue *q,
16 : : struct request *prev_rq, struct bio *prev, struct bio *next)
17 : : {
18 : : struct bio_vec pb, nb;
19 : :
20 [ + + - + ]: 5229480 : if (!bio_has_data(prev) || !queue_virt_boundary(q))
21 : : return false;
22 : :
23 : : /*
24 : : * Don't merge if the 1st bio starts with non-zero offset, otherwise it
25 : : * is quite difficult to respect the sg gap limit. We work hard to
26 : : * merge a huge number of small single bios in case of mkfs.
27 : : */
28 [ # # ]: 0 : if (prev_rq)
29 : 0 : bio_get_first_bvec(prev_rq->bio, &pb);
30 : : else
31 : 0 : bio_get_first_bvec(prev, &pb);
32 [ # # ]: 0 : if (pb.bv_offset & queue_virt_boundary(q))
33 : : return true;
34 : :
35 : : /*
36 : : * We don't need to worry about the situation that the merged segment
37 : : * ends in unaligned virt boundary:
38 : : *
39 : : * - if 'pb' ends aligned, the merged segment ends aligned
40 : : * - if 'pb' ends unaligned, the next bio must include
41 : : * one single bvec of 'nb', otherwise the 'nb' can't
42 : : * merge with 'pb'
43 : : */
44 : 0 : bio_get_last_bvec(prev, &pb);
45 : 0 : bio_get_first_bvec(next, &nb);
46 [ # # ]: 0 : if (biovec_phys_mergeable(q, &pb, &nb))
47 : : return false;
48 : 0 : return __bvec_gap_to_prev(q, &pb, nb.bv_offset);
49 : : }
50 : :
51 : : static inline bool req_gap_back_merge(struct request *req, struct bio *bio)
52 : : {
53 : 2559568 : return bio_will_gap(req->q, req, req->biotail, bio);
54 : : }
55 : :
56 : : static inline bool req_gap_front_merge(struct request *req, struct bio *bio)
57 : : {
58 : 55168 : return bio_will_gap(req->q, NULL, bio, req->bio);
59 : : }
60 : :
61 : 0 : static struct bio *blk_bio_discard_split(struct request_queue *q,
62 : : struct bio *bio,
63 : : struct bio_set *bs,
64 : : unsigned *nsegs)
65 : : {
66 : : unsigned int max_discard_sectors, granularity;
67 : : int alignment;
68 : : sector_t tmp;
69 : : unsigned split_sectors;
70 : :
71 : 0 : *nsegs = 1;
72 : :
73 : : /* Zero-sector (unknown) and one-sector granularities are the same. */
74 : 0 : granularity = max(q->limits.discard_granularity >> 9, 1U);
75 : :
76 : 0 : max_discard_sectors = min(q->limits.max_discard_sectors,
77 : : bio_allowed_max_sectors(q));
78 : 0 : max_discard_sectors -= max_discard_sectors % granularity;
79 : :
80 [ # # ]: 0 : if (unlikely(!max_discard_sectors)) {
81 : : /* XXX: warn */
82 : : return NULL;
83 : : }
84 : :
85 [ # # ]: 0 : if (bio_sectors(bio) <= max_discard_sectors)
86 : : return NULL;
87 : :
88 : : split_sectors = max_discard_sectors;
89 : :
90 : : /*
91 : : * If the next starting sector would be misaligned, stop the discard at
92 : : * the previous aligned sector.
93 : : */
94 : 0 : alignment = (q->limits.discard_alignment >> 9) % granularity;
95 : :
96 : 0 : tmp = bio->bi_iter.bi_sector + split_sectors - alignment;
97 [ # # # # : 0 : tmp = sector_div(tmp, granularity);
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98 : :
99 [ # # ]: 0 : if (split_sectors > tmp)
100 : 0 : split_sectors -= tmp;
101 : :
102 : 0 : return bio_split(bio, split_sectors, GFP_NOIO, bs);
103 : : }
104 : :
105 : 0 : static struct bio *blk_bio_write_zeroes_split(struct request_queue *q,
106 : : struct bio *bio, struct bio_set *bs, unsigned *nsegs)
107 : : {
108 : 0 : *nsegs = 0;
109 : :
110 [ # # ]: 0 : if (!q->limits.max_write_zeroes_sectors)
111 : : return NULL;
112 : :
113 [ # # ]: 0 : if (bio_sectors(bio) <= q->limits.max_write_zeroes_sectors)
114 : : return NULL;
115 : :
116 : 0 : return bio_split(bio, q->limits.max_write_zeroes_sectors, GFP_NOIO, bs);
117 : : }
118 : :
119 : 0 : static struct bio *blk_bio_write_same_split(struct request_queue *q,
120 : : struct bio *bio,
121 : : struct bio_set *bs,
122 : : unsigned *nsegs)
123 : : {
124 : 0 : *nsegs = 1;
125 : :
126 [ # # ]: 0 : if (!q->limits.max_write_same_sectors)
127 : : return NULL;
128 : :
129 [ # # ]: 0 : if (bio_sectors(bio) <= q->limits.max_write_same_sectors)
130 : : return NULL;
131 : :
132 : 0 : return bio_split(bio, q->limits.max_write_same_sectors, GFP_NOIO, bs);
133 : : }
134 : :
135 : : /*
136 : : * Return the maximum number of sectors from the start of a bio that may be
137 : : * submitted as a single request to a block device. If enough sectors remain,
138 : : * align the end to the physical block size. Otherwise align the end to the
139 : : * logical block size. This approach minimizes the number of non-aligned
140 : : * requests that are submitted to a block device if the start of a bio is not
141 : : * aligned to a physical block boundary.
142 : : */
143 : 5583324 : static inline unsigned get_max_io_size(struct request_queue *q,
144 : : struct bio *bio)
145 : : {
146 : 5583324 : unsigned sectors = blk_max_size_offset(q, bio->bi_iter.bi_sector);
147 : : unsigned max_sectors = sectors;
148 : 5583324 : unsigned pbs = queue_physical_block_size(q) >> SECTOR_SHIFT;
149 : 5583324 : unsigned lbs = queue_logical_block_size(q) >> SECTOR_SHIFT;
150 : 5583324 : unsigned start_offset = bio->bi_iter.bi_sector & (pbs - 1);
151 : :
152 : 5583324 : max_sectors += start_offset;
153 : 5583324 : max_sectors &= ~(pbs - 1);
154 [ + - ]: 5583324 : if (max_sectors > start_offset)
155 : 5583324 : return max_sectors - start_offset;
156 : :
157 : 0 : return sectors & (lbs - 1);
158 : : }
159 : :
160 : : static inline unsigned get_max_segment_size(const struct request_queue *q,
161 : : struct page *start_page,
162 : : unsigned long offset)
163 : : {
164 : : unsigned long mask = queue_segment_boundary(q);
165 : :
166 : 1683324 : offset = mask & (page_to_phys(start_page) + offset);
167 : :
168 : : /*
169 : : * overflow may be triggered in case of zero page physical address
170 : : * on 32bit arch, use queue's max segment size when that happens.
171 : : */
172 [ + - + - : 3366648 : return min_not_zero(mask - offset + 1,
+ + + + ]
173 : : (unsigned long)queue_max_segment_size(q));
174 : : }
175 : :
176 : : /**
177 : : * bvec_split_segs - verify whether or not a bvec should be split in the middle
178 : : * @q: [in] request queue associated with the bio associated with @bv
179 : : * @bv: [in] bvec to examine
180 : : * @nsegs: [in,out] Number of segments in the bio being built. Incremented
181 : : * by the number of segments from @bv that may be appended to that
182 : : * bio without exceeding @max_segs
183 : : * @sectors: [in,out] Number of sectors in the bio being built. Incremented
184 : : * by the number of sectors from @bv that may be appended to that
185 : : * bio without exceeding @max_sectors
186 : : * @max_segs: [in] upper bound for *@nsegs
187 : : * @max_sectors: [in] upper bound for *@sectors
188 : : *
189 : : * When splitting a bio, it can happen that a bvec is encountered that is too
190 : : * big to fit in a single segment and hence that it has to be split in the
191 : : * middle. This function verifies whether or not that should happen. The value
192 : : * %true is returned if and only if appending the entire @bv to a bio with
193 : : * *@nsegs segments and *@sectors sectors would make that bio unacceptable for
194 : : * the block driver.
195 : : */
196 : 841784 : static bool bvec_split_segs(const struct request_queue *q,
197 : : const struct bio_vec *bv, unsigned *nsegs,
198 : : unsigned *sectors, unsigned max_segs,
199 : : unsigned max_sectors)
200 : : {
201 : 841784 : unsigned max_len = (min(max_sectors, UINT_MAX >> 9) - *sectors) << 9;
202 : 841784 : unsigned len = min(bv->bv_len, max_len);
203 : : unsigned total_len = 0;
204 : : unsigned seg_size = 0;
205 : :
206 [ + + + + ]: 2525336 : while (len && *nsegs < max_segs) {
207 : 841730 : seg_size = get_max_segment_size(q, bv->bv_page,
208 : 841730 : bv->bv_offset + total_len);
209 : 841730 : seg_size = min(seg_size, len);
210 : :
211 : 841730 : (*nsegs)++;
212 : 841730 : total_len += seg_size;
213 : 841730 : len -= seg_size;
214 : :
215 [ + - ]: 1683460 : if ((bv->bv_offset + total_len) & queue_virt_boundary(q))
216 : : break;
217 : : }
218 : :
219 : 841784 : *sectors += total_len >> 9;
220 : :
221 : : /* tell the caller to split the bvec if it is too big to fit */
222 [ + + + + ]: 841784 : return len > 0 || bv->bv_len > max_len;
223 : : }
224 : :
225 : : /**
226 : : * blk_bio_segment_split - split a bio in two bios
227 : : * @q: [in] request queue pointer
228 : : * @bio: [in] bio to be split
229 : : * @bs: [in] bio set to allocate the clone from
230 : : * @segs: [out] number of segments in the bio with the first half of the sectors
231 : : *
232 : : * Clone @bio, update the bi_iter of the clone to represent the first sectors
233 : : * of @bio and update @bio->bi_iter to represent the remaining sectors. The
234 : : * following is guaranteed for the cloned bio:
235 : : * - That it has at most get_max_io_size(@q, @bio) sectors.
236 : : * - That it has at most queue_max_segments(@q) segments.
237 : : *
238 : : * Except for discard requests the cloned bio will point at the bi_io_vec of
239 : : * the original bio. It is the responsibility of the caller to ensure that the
240 : : * original bio is not freed before the cloned bio. The caller is also
241 : : * responsible for ensuring that @bs is only destroyed after processing of the
242 : : * split bio has finished.
243 : : */
244 : 5583280 : static struct bio *blk_bio_segment_split(struct request_queue *q,
245 : : struct bio *bio,
246 : : struct bio_set *bs,
247 : : unsigned *segs)
248 : : {
249 : : struct bio_vec bv, bvprv, *bvprvp = NULL;
250 : : struct bvec_iter iter;
251 : 5583280 : unsigned nsegs = 0, sectors = 0;
252 : 5583280 : const unsigned max_sectors = get_max_io_size(q, bio);
253 : 5583378 : const unsigned max_segs = queue_max_segments(q);
254 : :
255 [ + + ]: 13391612 : bio_for_each_bvec(bv, bio, iter) {
256 : : /*
257 : : * If the queue doesn't support SG gaps and adding this
258 : : * offset would create a gap, disallow it.
259 : : */
260 [ + + + + ]: 10033108 : if (bvprvp && bvec_gap_to_prev(q, bvprvp, bv.bv_offset))
261 : : goto split;
262 : :
263 [ + - + + ]: 15616232 : if (nsegs < max_segs &&
264 [ + + ]: 15616416 : sectors + (bv.bv_len >> 9) <= max_sectors &&
265 : 7808300 : bv.bv_offset + bv.bv_len <= PAGE_SIZE) {
266 : 6966472 : nsegs++;
267 : 6966472 : sectors += bv.bv_len >> 9;
268 [ + + ]: 841644 : } else if (bvec_split_segs(q, &bv, &nsegs, §ors, max_segs,
269 : : max_sectors)) {
270 : : goto split;
271 : : }
272 : :
273 : 7808234 : bvprv = bv;
274 : : bvprvp = &bvprv;
275 : : }
276 : :
277 : 5583386 : *segs = nsegs;
278 : 5583386 : return NULL;
279 : : split:
280 : 90 : *segs = nsegs;
281 : 90 : return bio_split(bio, sectors, GFP_NOIO, bs);
282 : : }
283 : :
284 : : /**
285 : : * __blk_queue_split - split a bio and submit the second half
286 : : * @q: [in] request queue pointer
287 : : * @bio: [in, out] bio to be split
288 : : * @nr_segs: [out] number of segments in the first bio
289 : : *
290 : : * Split a bio into two bios, chain the two bios, submit the second half and
291 : : * store a pointer to the first half in *@bio. If the second bio is still too
292 : : * big it will be split by a recursive call to this function. Since this
293 : : * function may allocate a new bio from @q->bio_split, it is the responsibility
294 : : * of the caller to ensure that @q is only released after processing of the
295 : : * split bio has finished.
296 : : */
297 : 5583116 : void __blk_queue_split(struct request_queue *q, struct bio **bio,
298 : : unsigned int *nr_segs)
299 : : {
300 : : struct bio *split;
301 : :
302 [ - - - + ]: 5583116 : switch (bio_op(*bio)) {
303 : : case REQ_OP_DISCARD:
304 : : case REQ_OP_SECURE_ERASE:
305 : 0 : split = blk_bio_discard_split(q, *bio, &q->bio_split, nr_segs);
306 : 0 : break;
307 : : case REQ_OP_WRITE_ZEROES:
308 : 0 : split = blk_bio_write_zeroes_split(q, *bio, &q->bio_split,
309 : : nr_segs);
310 : 0 : break;
311 : : case REQ_OP_WRITE_SAME:
312 : 0 : split = blk_bio_write_same_split(q, *bio, &q->bio_split,
313 : : nr_segs);
314 : 0 : break;
315 : : default:
316 : 5583116 : split = blk_bio_segment_split(q, *bio, &q->bio_split, nr_segs);
317 : 5583260 : break;
318 : : }
319 : :
320 [ + + ]: 5583260 : if (split) {
321 : : /* there isn't chance to merge the splitted bio */
322 : 10 : split->bi_opf |= REQ_NOMERGE;
323 : :
324 : : /*
325 : : * Since we're recursing into make_request here, ensure
326 : : * that we mark this bio as already having entered the queue.
327 : : * If not, and the queue is going away, we can get stuck
328 : : * forever on waiting for the queue reference to drop. But
329 : : * that will never happen, as we're already holding a
330 : : * reference to it.
331 : : */
332 : 10 : bio_set_flag(*bio, BIO_QUEUE_ENTERED);
333 : :
334 : 10 : bio_chain(split, *bio);
335 : 10 : trace_block_split(q, split, (*bio)->bi_iter.bi_sector);
336 : 10 : generic_make_request(*bio);
337 : 10 : *bio = split;
338 : : }
339 : 5583260 : }
340 : :
341 : : /**
342 : : * blk_queue_split - split a bio and submit the second half
343 : : * @q: [in] request queue pointer
344 : : * @bio: [in, out] bio to be split
345 : : *
346 : : * Split a bio into two bios, chains the two bios, submit the second half and
347 : : * store a pointer to the first half in *@bio. Since this function may allocate
348 : : * a new bio from @q->bio_split, it is the responsibility of the caller to
349 : : * ensure that @q is only released after processing of the split bio has
350 : : * finished.
351 : : */
352 : 0 : void blk_queue_split(struct request_queue *q, struct bio **bio)
353 : : {
354 : : unsigned int nr_segs;
355 : :
356 : 0 : __blk_queue_split(q, bio, &nr_segs);
357 : 0 : }
358 : : EXPORT_SYMBOL(blk_queue_split);
359 : :
360 : 0 : unsigned int blk_recalc_rq_segments(struct request *rq)
361 : : {
362 : 0 : unsigned int nr_phys_segs = 0;
363 : 0 : unsigned int nr_sectors = 0;
364 : : struct req_iterator iter;
365 : : struct bio_vec bv;
366 : :
367 [ # # ]: 0 : if (!rq->bio)
368 : : return 0;
369 : :
370 [ # # # ]: 0 : switch (bio_op(rq->bio)) {
371 : : case REQ_OP_DISCARD:
372 : : case REQ_OP_SECURE_ERASE:
373 : : case REQ_OP_WRITE_ZEROES:
374 : : return 0;
375 : : case REQ_OP_WRITE_SAME:
376 : 0 : return 1;
377 : : }
378 : :
379 [ # # # # : 0 : rq_for_each_bvec(bv, rq, iter)
# # ]
380 : 0 : bvec_split_segs(rq->q, &bv, &nr_phys_segs, &nr_sectors,
381 : : UINT_MAX, UINT_MAX);
382 : 0 : return nr_phys_segs;
383 : : }
384 : :
385 : : static inline struct scatterlist *blk_next_sg(struct scatterlist **sg,
386 : : struct scatterlist *sglist)
387 : : {
388 [ + + + + ]: 6304336 : if (!*sg)
389 : : return sglist;
390 : :
391 : : /*
392 : : * If the driver previously mapped a shorter list, we could see a
393 : : * termination bit prematurely unless it fully inits the sg table
394 : : * on each mapping. We KNOW that there must be more entries here
395 : : * or the driver would be buggy, so force clear the termination bit
396 : : * to avoid doing a full sg_init_table() in drivers for each command.
397 : : */
398 : : sg_unmark_end(*sg);
399 : 3334990 : return sg_next(*sg);
400 : : }
401 : :
402 : 841594 : static unsigned blk_bvec_map_sg(struct request_queue *q,
403 : : struct bio_vec *bvec, struct scatterlist *sglist,
404 : : struct scatterlist **sg)
405 : : {
406 : 841594 : unsigned nbytes = bvec->bv_len;
407 : : unsigned nsegs = 0, total = 0;
408 : :
409 [ + + ]: 2524782 : while (nbytes > 0) {
410 : 841594 : unsigned offset = bvec->bv_offset + total;
411 : 1683188 : unsigned len = min(get_max_segment_size(q, bvec->bv_page,
412 : : offset), nbytes);
413 : : struct page *page = bvec->bv_page;
414 : :
415 : : /*
416 : : * Unfortunately a fair number of drivers barf on scatterlists
417 : : * that have an offset larger than PAGE_SIZE, despite other
418 : : * subsystems dealing with that invariant just fine. For now
419 : : * stick to the legacy format where we never present those from
420 : : * the block layer, but the code below should be removed once
421 : : * these offenders (mostly MMC/SD drivers) are fixed.
422 : : */
423 : 841594 : page += (offset >> PAGE_SHIFT);
424 : 841594 : offset &= ~PAGE_MASK;
425 : :
426 : 841594 : *sg = blk_next_sg(sg, sglist);
427 : : sg_set_page(*sg, page, len, offset);
428 : :
429 : 841594 : total += len;
430 : 841594 : nbytes -= len;
431 : 841594 : nsegs++;
432 : : }
433 : :
434 : 841594 : return nsegs;
435 : : }
436 : :
437 : 5462742 : static inline int __blk_bvec_map_sg(struct bio_vec bv,
438 : : struct scatterlist *sglist, struct scatterlist **sg)
439 : : {
440 : 5462742 : *sg = blk_next_sg(sg, sglist);
441 : 5462742 : sg_set_page(*sg, bv.bv_page, bv.bv_len, bv.bv_offset);
442 : 5462742 : return 1;
443 : : }
444 : :
445 : : /* only try to merge bvecs into one sg if they are from two bios */
446 : : static inline bool
447 : 2613894 : __blk_segment_map_sg_merge(struct request_queue *q, struct bio_vec *bvec,
448 : : struct bio_vec *bvprv, struct scatterlist **sg)
449 : : {
450 : :
451 : 2613894 : int nbytes = bvec->bv_len;
452 : :
453 [ + - ]: 2613894 : if (!*sg)
454 : : return false;
455 : :
456 [ + - ]: 5227788 : if ((*sg)->length + nbytes > queue_max_segment_size(q))
457 : : return false;
458 : :
459 [ + + ]: 2613894 : if (!biovec_phys_mergeable(q, bvprv, bvec))
460 : : return false;
461 : :
462 : 1503790 : (*sg)->length += nbytes;
463 : :
464 : 1503790 : return true;
465 : : }
466 : :
467 : 2969344 : static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio,
468 : : struct scatterlist *sglist,
469 : : struct scatterlist **sg)
470 : : {
471 : 2969344 : struct bio_vec uninitialized_var(bvec), bvprv = { NULL };
472 : : struct bvec_iter iter;
473 : : int nsegs = 0;
474 : : bool new_bio = false;
475 : :
476 [ + + ]: 8552582 : for_each_bio(bio) {
477 [ + + ]: 13391362 : bio_for_each_bvec(bvec, bio, iter) {
478 : : /*
479 : : * Only try to merge bvecs from two bios given we
480 : : * have done bio internal merge when adding pages
481 : : * to bio
482 : : */
483 [ + + + + ]: 10422018 : if (new_bio &&
484 : 2613894 : __blk_segment_map_sg_merge(q, &bvec, &bvprv, sg))
485 : : goto next_bvec;
486 : :
487 [ + + ]: 6304334 : if (bvec.bv_offset + bvec.bv_len <= PAGE_SIZE)
488 : 5462740 : nsegs += __blk_bvec_map_sg(bvec, sglist, sg);
489 : : else
490 : 841594 : nsegs += blk_bvec_map_sg(q, &bvec, sglist, sg);
491 : : next_bvec:
492 : : new_bio = false;
493 : : }
494 [ + - ]: 5583238 : if (likely(bio->bi_iter.bi_size)) {
495 : 5583238 : bvprv = bvec;
496 : : new_bio = true;
497 : : }
498 : : }
499 : :
500 : 2969344 : return nsegs;
501 : : }
502 : :
503 : : /*
504 : : * map a request to scatterlist, return number of sg entries setup. Caller
505 : : * must make sure sg can hold rq->nr_phys_segments entries
506 : : */
507 : 2969344 : int blk_rq_map_sg(struct request_queue *q, struct request *rq,
508 : : struct scatterlist *sglist)
509 : : {
510 : 2969344 : struct scatterlist *sg = NULL;
511 : : int nsegs = 0;
512 : :
513 [ - + ]: 2969344 : if (rq->rq_flags & RQF_SPECIAL_PAYLOAD)
514 : 0 : nsegs = __blk_bvec_map_sg(rq->special_vec, sglist, &sg);
515 [ + - - + ]: 2969344 : else if (rq->bio && bio_op(rq->bio) == REQ_OP_WRITE_SAME)
516 : 0 : nsegs = __blk_bvec_map_sg(bio_iovec(rq->bio), sglist, &sg);
517 [ + - ]: 2969344 : else if (rq->bio)
518 : 2969344 : nsegs = __blk_bios_map_sg(q, rq->bio, sglist, &sg);
519 : :
520 [ - + # # ]: 2969344 : if (unlikely(rq->rq_flags & RQF_COPY_USER) &&
521 : 0 : (blk_rq_bytes(rq) & q->dma_pad_mask)) {
522 : 0 : unsigned int pad_len =
523 : 0 : (q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1;
524 : :
525 : 0 : sg->length += pad_len;
526 : 0 : rq->extra_len += pad_len;
527 : : }
528 : :
529 [ - + # # ]: 2969344 : if (q->dma_drain_size && q->dma_drain_needed(rq)) {
530 [ # # ]: 0 : if (op_is_write(req_op(rq)))
531 : 0 : memset(q->dma_drain_buffer, 0, q->dma_drain_size);
532 : :
533 : 0 : sg_unmark_end(sg);
534 : 0 : sg = sg_next(sg);
535 : 0 : sg_set_page(sg, virt_to_page(q->dma_drain_buffer),
536 : : q->dma_drain_size,
537 : : ((unsigned long)q->dma_drain_buffer) &
538 : : (PAGE_SIZE - 1));
539 : 0 : nsegs++;
540 : 0 : rq->extra_len += q->dma_drain_size;
541 : : }
542 : :
543 [ + - ]: 2969344 : if (sg)
544 : : sg_mark_end(sg);
545 : :
546 : : /*
547 : : * Something must have been wrong if the figured number of
548 : : * segment is bigger than number of req's physical segments
549 : : */
550 [ - + ]: 2969344 : WARN_ON(nsegs > blk_rq_nr_phys_segments(rq));
551 : :
552 : 2969344 : return nsegs;
553 : : }
554 : : EXPORT_SYMBOL(blk_rq_map_sg);
555 : :
556 : : static inline int ll_new_hw_segment(struct request *req, struct bio *bio,
557 : : unsigned int nr_phys_segs)
558 : : {
559 [ + - + + ]: 5128336 : if (req->nr_phys_segments + nr_phys_segs > queue_max_segments(req->q))
560 : : goto no_merge;
561 : :
562 : : if (blk_integrity_merge_bio(req->q, req, bio) == false)
563 : : goto no_merge;
564 : :
565 : : /*
566 : : * This will form the start of a new hw segment. Bump both
567 : : * counters.
568 : : */
569 : 2564028 : req->nr_phys_segments += nr_phys_segs;
570 : : return 1;
571 : :
572 : : no_merge:
573 : : req_set_nomerge(req->q, req);
574 : : return 0;
575 : : }
576 : :
577 : 2509356 : int ll_back_merge_fn(struct request *req, struct bio *bio, unsigned int nr_segs)
578 : : {
579 [ + - ]: 2509358 : if (req_gap_back_merge(req, bio))
580 : : return 0;
581 : : if (blk_integrity_rq(req) &&
582 : : integrity_req_gap_back_merge(req, bio))
583 : : return 0;
584 [ + + ]: 5018716 : if (blk_rq_sectors(req) + bio_sectors(bio) >
585 : 2509358 : blk_rq_get_max_sectors(req, blk_rq_pos(req))) {
586 : 358 : req_set_nomerge(req->q, req);
587 : : return 0;
588 : : }
589 : :
590 : 2509000 : return ll_new_hw_segment(req, bio, nr_segs);
591 : : }
592 : :
593 : 55168 : int ll_front_merge_fn(struct request *req, struct bio *bio, unsigned int nr_segs)
594 : : {
595 [ + - ]: 55168 : if (req_gap_front_merge(req, bio))
596 : : return 0;
597 : : if (blk_integrity_rq(req) &&
598 : : integrity_req_gap_front_merge(req, bio))
599 : : return 0;
600 [ - + ]: 110336 : if (blk_rq_sectors(req) + bio_sectors(bio) >
601 : 55168 : blk_rq_get_max_sectors(req, bio->bi_iter.bi_sector)) {
602 : 0 : req_set_nomerge(req->q, req);
603 : : return 0;
604 : : }
605 : :
606 : 55168 : return ll_new_hw_segment(req, bio, nr_segs);
607 : : }
608 : :
609 : 0 : static bool req_attempt_discard_merge(struct request_queue *q, struct request *req,
610 : : struct request *next)
611 : : {
612 : : unsigned short segments = blk_rq_nr_discard_segments(req);
613 : :
614 [ # # ]: 0 : if (segments >= queue_max_discard_segments(q))
615 : : goto no_merge;
616 [ # # ]: 0 : if (blk_rq_sectors(req) + bio_sectors(next->bio) >
617 : 0 : blk_rq_get_max_sectors(req, blk_rq_pos(req)))
618 : : goto no_merge;
619 : :
620 : 0 : req->nr_phys_segments = segments + blk_rq_nr_discard_segments(next);
621 : 0 : return true;
622 : : no_merge:
623 : : req_set_nomerge(q, req);
624 : : return false;
625 : : }
626 : :
627 : 50212 : static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
628 : : struct request *next)
629 : : {
630 : : int total_phys_segments;
631 : :
632 [ + - ]: 100424 : if (req_gap_back_merge(req, next->bio))
633 : : return 0;
634 : :
635 : : /*
636 : : * Will it become too large?
637 : : */
638 [ + + ]: 100424 : if ((blk_rq_sectors(req) + blk_rq_sectors(next)) >
639 : 50212 : blk_rq_get_max_sectors(req, blk_rq_pos(req)))
640 : : return 0;
641 : :
642 : 49982 : total_phys_segments = req->nr_phys_segments + next->nr_phys_segments;
643 [ + - ]: 49982 : if (total_phys_segments > queue_max_segments(q))
644 : : return 0;
645 : :
646 : : if (blk_integrity_merge_rq(q, req, next) == false)
647 : : return 0;
648 : :
649 : : /* Merge is OK... */
650 : 49982 : req->nr_phys_segments = total_phys_segments;
651 : 49982 : return 1;
652 : : }
653 : :
654 : : /**
655 : : * blk_rq_set_mixed_merge - mark a request as mixed merge
656 : : * @rq: request to mark as mixed merge
657 : : *
658 : : * Description:
659 : : * @rq is about to be mixed merged. Make sure the attributes
660 : : * which can be mixed are set in each bio and mark @rq as mixed
661 : : * merged.
662 : : */
663 : 2122106 : void blk_rq_set_mixed_merge(struct request *rq)
664 : : {
665 : 2122106 : unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK;
666 : : struct bio *bio;
667 : :
668 [ + + ]: 2122106 : if (rq->rq_flags & RQF_MIXED_MERGE)
669 : 2122106 : return;
670 : :
671 : : /*
672 : : * @rq will no longer represent mixable attributes for all the
673 : : * contained bios. It will just track those of the first one.
674 : : * Distributes the attributs to each bio.
675 : : */
676 [ + + ]: 402756 : for (bio = rq->bio; bio; bio = bio->bi_next) {
677 [ - + # # : 201380 : WARN_ON_ONCE((bio->bi_opf & REQ_FAILFAST_MASK) &&
- + # # ]
678 : : (bio->bi_opf & REQ_FAILFAST_MASK) != ff);
679 : 201380 : bio->bi_opf |= ff;
680 : : }
681 : 201376 : rq->rq_flags |= RQF_MIXED_MERGE;
682 : : }
683 : :
684 : 49982 : static void blk_account_io_merge(struct request *req)
685 : : {
686 [ + - ]: 49982 : if (blk_do_io_stat(req)) {
687 : : struct hd_struct *part;
688 : :
689 : 49982 : part_stat_lock();
690 : 49982 : part = req->part;
691 : :
692 : 99964 : part_dec_in_flight(req->q, part, rq_data_dir(req));
693 : :
694 : : hd_struct_put(part);
695 : 49982 : part_stat_unlock();
696 : : }
697 : 49982 : }
698 : : /*
699 : : * Two cases of handling DISCARD merge:
700 : : * If max_discard_segments > 1, the driver takes every bio
701 : : * as a range and send them to controller together. The ranges
702 : : * needn't to be contiguous.
703 : : * Otherwise, the bios/requests will be handled as same as
704 : : * others which should be contiguous.
705 : : */
706 : : static inline bool blk_discard_mergable(struct request *req)
707 : : {
708 [ - + # # : 3928522 : if (req_op(req) == REQ_OP_DISCARD &&
- + # # -
+ # # ]
709 : 0 : queue_max_discard_segments(req->q) > 1)
710 : : return true;
711 : : return false;
712 : : }
713 : :
714 : 224456 : static enum elv_merge blk_try_req_merge(struct request *req,
715 : : struct request *next)
716 : : {
717 [ + - ]: 224456 : if (blk_discard_mergable(req))
718 : : return ELEVATOR_DISCARD_MERGE;
719 [ + + ]: 448912 : else if (blk_rq_pos(req) + blk_rq_sectors(req) == blk_rq_pos(next))
720 : : return ELEVATOR_BACK_MERGE;
721 : :
722 : 174244 : return ELEVATOR_NO_MERGE;
723 : : }
724 : :
725 : : /*
726 : : * For non-mq, this has to be called with the request spinlock acquired.
727 : : * For mq with scheduling, the appropriate queue wide lock should be held.
728 : : */
729 : 235672 : static struct request *attempt_merge(struct request_queue *q,
730 : : struct request *req, struct request *next)
731 : : {
732 [ + - + - ]: 235672 : if (!rq_mergeable(req) || !rq_mergeable(next))
733 : : return NULL;
734 : :
735 [ + + ]: 235672 : if (req_op(req) != req_op(next))
736 : : return NULL;
737 : :
738 [ + - ]: 224456 : if (rq_data_dir(req) != rq_data_dir(next)
739 [ + - ]: 224456 : || req->rq_disk != next->rq_disk)
740 : : return NULL;
741 : :
742 [ - + # # ]: 224456 : if (req_op(req) == REQ_OP_WRITE_SAME &&
743 : 0 : !blk_write_same_mergeable(req->bio, next->bio))
744 : : return NULL;
745 : :
746 : : /*
747 : : * Don't allow merge of different write hints, or for a hint with
748 : : * non-hint IO.
749 : : */
750 [ + - ]: 224456 : if (req->write_hint != next->write_hint)
751 : : return NULL;
752 : :
753 [ + - ]: 224456 : if (req->ioprio != next->ioprio)
754 : : return NULL;
755 : :
756 : : /*
757 : : * If we are allowed to merge, then append bio list
758 : : * from next to rq and release next. merge_requests_fn
759 : : * will have updated segment counts, update sector
760 : : * counts here. Handle DISCARDs separately, as they
761 : : * have separate settings.
762 : : */
763 : :
764 [ - + + ]: 224456 : switch (blk_try_req_merge(req, next)) {
765 : : case ELEVATOR_DISCARD_MERGE:
766 [ # # ]: 0 : if (!req_attempt_discard_merge(q, req, next))
767 : : return NULL;
768 : : break;
769 : : case ELEVATOR_BACK_MERGE:
770 [ + + ]: 50212 : if (!ll_merge_requests_fn(q, req, next))
771 : : return NULL;
772 : : break;
773 : : default:
774 : : return NULL;
775 : : }
776 : :
777 : : /*
778 : : * If failfast settings disagree or any of the two is already
779 : : * a mixed merge, mark both as mixed before proceeding. This
780 : : * makes sure that all involved bios have mixable attributes
781 : : * set properly.
782 : : */
783 [ + + - + ]: 58710 : if (((req->rq_flags | next->rq_flags) & RQF_MIXED_MERGE) ||
784 : 17456 : (req->cmd_flags & REQ_FAILFAST_MASK) !=
785 : 8728 : (next->cmd_flags & REQ_FAILFAST_MASK)) {
786 : 41254 : blk_rq_set_mixed_merge(req);
787 : 41254 : blk_rq_set_mixed_merge(next);
788 : : }
789 : :
790 : : /*
791 : : * At this point we have either done a back merge or front merge. We
792 : : * need the smaller start_time_ns of the merged requests to be the
793 : : * current request for accounting purposes.
794 : : */
795 [ + + ]: 49982 : if (next->start_time_ns < req->start_time_ns)
796 : 146 : req->start_time_ns = next->start_time_ns;
797 : :
798 : 49982 : req->biotail->bi_next = next->bio;
799 : 49982 : req->biotail = next->biotail;
800 : :
801 : 49982 : req->__data_len += blk_rq_bytes(next);
802 : :
803 [ + - ]: 49982 : if (!blk_discard_mergable(req))
804 : 49982 : elv_merge_requests(q, req, next);
805 : :
806 : : /*
807 : : * 'next' is going away, so update stats accordingly
808 : : */
809 : 49982 : blk_account_io_merge(next);
810 : :
811 : : /*
812 : : * ownership of bio passed from next to req, return 'next' for
813 : : * the caller to free
814 : : */
815 : 49982 : next->bio = NULL;
816 : 49982 : return next;
817 : : }
818 : :
819 : 647342 : struct request *attempt_back_merge(struct request_queue *q, struct request *rq)
820 : : {
821 : 647342 : struct request *next = elv_latter_request(q, rq);
822 : :
823 [ + + ]: 647342 : if (next)
824 : 23264 : return attempt_merge(q, rq, next);
825 : :
826 : : return NULL;
827 : : }
828 : :
829 : 582 : struct request *attempt_front_merge(struct request_queue *q, struct request *rq)
830 : : {
831 : 582 : struct request *prev = elv_former_request(q, rq);
832 : :
833 [ + + ]: 582 : if (prev)
834 : 106 : return attempt_merge(q, prev, rq);
835 : :
836 : : return NULL;
837 : : }
838 : :
839 : 212302 : int blk_attempt_req_merge(struct request_queue *q, struct request *rq,
840 : : struct request *next)
841 : : {
842 : : struct request *free;
843 : :
844 : 212302 : free = attempt_merge(q, rq, next);
845 [ + + ]: 212302 : if (free) {
846 : 49000 : blk_put_request(free);
847 : 49000 : return 1;
848 : : }
849 : :
850 : : return 0;
851 : : }
852 : :
853 : 3672916 : bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
854 : : {
855 [ + + + + ]: 7345828 : if (!rq_mergeable(rq) || !bio_mergeable(bio))
856 : : return false;
857 : :
858 [ + + ]: 3672870 : if (req_op(rq) != bio_op(bio))
859 : : return false;
860 : :
861 : : /* different data direction or already started, don't merge */
862 [ + + ]: 3658806 : if (bio_data_dir(bio) != rq_data_dir(rq))
863 : : return false;
864 : :
865 : : /* must be same device */
866 [ + - ]: 3658806 : if (rq->rq_disk != bio->bi_disk)
867 : : return false;
868 : :
869 : : /* only merge integrity protected bio into ditto rq */
870 : : if (blk_integrity_merge_bio(rq->q, rq, bio) == false)
871 : : return false;
872 : :
873 : : /* must be using the same buffer */
874 [ - + # # ]: 3658814 : if (req_op(rq) == REQ_OP_WRITE_SAME &&
875 : 0 : !blk_write_same_mergeable(rq->bio, bio))
876 : : return false;
877 : :
878 : : /*
879 : : * Don't allow merge of different write hints, or for a hint with
880 : : * non-hint IO.
881 : : */
882 [ + - ]: 3658808 : if (rq->write_hint != bio->bi_write_hint)
883 : : return false;
884 : :
885 [ + + ]: 3658808 : if (rq->ioprio != bio_prio(bio))
886 : : return false;
887 : :
888 : 3658812 : return true;
889 : : }
890 : :
891 : 3654084 : enum elv_merge blk_try_merge(struct request *rq, struct bio *bio)
892 : : {
893 [ + + ]: 3654084 : if (blk_discard_mergable(rq))
894 : : return ELEVATOR_DISCARD_MERGE;
895 [ + + ]: 3654076 : else if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_iter.bi_sector)
896 : : return ELEVATOR_BACK_MERGE;
897 [ + + ]: 1149316 : else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_iter.bi_sector)
898 : : return ELEVATOR_FRONT_MERGE;
899 : 1094292 : return ELEVATOR_NO_MERGE;
900 : : }
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