]>
git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blob - block/blk-merge.c
2 * Functions related to segment and merge handling
4 #include <linux/kernel.h>
5 #include <linux/module.h>
7 #include <linux/blkdev.h>
8 #include <linux/scatterlist.h>
12 static unsigned int __blk_recalc_rq_segments(struct request_queue
*q
,
15 struct bio_vec
*bv
, *bvprv
= NULL
;
16 int cluster
, i
, high
, highprv
= 1;
17 unsigned int seg_size
, nr_phys_segs
;
18 struct bio
*fbio
, *bbio
;
24 cluster
= blk_queue_cluster(q
);
28 bio_for_each_segment(bv
, bio
, i
) {
30 * the trick here is making sure that a high page is
31 * never considered part of another segment, since that
32 * might change with the bounce page.
34 high
= page_to_pfn(bv
->bv_page
) > queue_bounce_pfn(q
);
38 if (seg_size
+ bv
->bv_len
39 > queue_max_segment_size(q
))
41 if (!BIOVEC_PHYS_MERGEABLE(bvprv
, bv
))
43 if (!BIOVEC_SEG_BOUNDARY(q
, bvprv
, bv
))
46 seg_size
+= bv
->bv_len
;
51 if (nr_phys_segs
== 1 && seg_size
>
52 fbio
->bi_seg_front_size
)
53 fbio
->bi_seg_front_size
= seg_size
;
57 seg_size
= bv
->bv_len
;
63 if (nr_phys_segs
== 1 && seg_size
> fbio
->bi_seg_front_size
)
64 fbio
->bi_seg_front_size
= seg_size
;
65 if (seg_size
> bbio
->bi_seg_back_size
)
66 bbio
->bi_seg_back_size
= seg_size
;
71 void blk_recalc_rq_segments(struct request
*rq
)
73 rq
->nr_phys_segments
= __blk_recalc_rq_segments(rq
->q
, rq
->bio
);
76 void blk_recount_segments(struct request_queue
*q
, struct bio
*bio
)
78 struct bio
*nxt
= bio
->bi_next
;
81 bio
->bi_phys_segments
= __blk_recalc_rq_segments(q
, bio
);
83 bio
->bi_flags
|= (1 << BIO_SEG_VALID
);
85 EXPORT_SYMBOL(blk_recount_segments
);
87 static int blk_phys_contig_segment(struct request_queue
*q
, struct bio
*bio
,
90 if (!blk_queue_cluster(q
))
93 if (bio
->bi_seg_back_size
+ nxt
->bi_seg_front_size
>
94 queue_max_segment_size(q
))
97 if (!bio_has_data(bio
))
100 if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio
), __BVEC_START(nxt
)))
104 * bio and nxt are contiguous in memory; check if the queue allows
105 * these two to be merged into one
107 if (BIO_SEG_BOUNDARY(q
, bio
, nxt
))
114 __blk_segment_map_sg(struct request_queue
*q
, struct bio_vec
*bvec
,
115 struct scatterlist
*sglist
, struct bio_vec
**bvprv
,
116 struct scatterlist
**sg
, int *nsegs
, int *cluster
)
119 int nbytes
= bvec
->bv_len
;
121 if (*bvprv
&& *cluster
) {
122 if ((*sg
)->length
+ nbytes
> queue_max_segment_size(q
))
125 if (!BIOVEC_PHYS_MERGEABLE(*bvprv
, bvec
))
127 if (!BIOVEC_SEG_BOUNDARY(q
, *bvprv
, bvec
))
130 (*sg
)->length
+= nbytes
;
137 * If the driver previously mapped a shorter
138 * list, we could see a termination bit
139 * prematurely unless it fully inits the sg
140 * table on each mapping. We KNOW that there
141 * must be more entries here or the driver
142 * would be buggy, so force clear the
143 * termination bit to avoid doing a full
144 * sg_init_table() in drivers for each command.
146 (*sg
)->page_link
&= ~0x02;
150 sg_set_page(*sg
, bvec
->bv_page
, nbytes
, bvec
->bv_offset
);
157 * map a request to scatterlist, return number of sg entries setup. Caller
158 * must make sure sg can hold rq->nr_phys_segments entries
160 int blk_rq_map_sg(struct request_queue
*q
, struct request
*rq
,
161 struct scatterlist
*sglist
)
163 struct bio_vec
*bvec
, *bvprv
;
164 struct req_iterator iter
;
165 struct scatterlist
*sg
;
169 cluster
= blk_queue_cluster(q
);
176 rq_for_each_segment(bvec
, rq
, iter
) {
177 __blk_segment_map_sg(q
, bvec
, sglist
, &bvprv
, &sg
,
179 } /* segments in rq */
182 if (unlikely(rq
->cmd_flags
& REQ_COPY_USER
) &&
183 (blk_rq_bytes(rq
) & q
->dma_pad_mask
)) {
184 unsigned int pad_len
=
185 (q
->dma_pad_mask
& ~blk_rq_bytes(rq
)) + 1;
187 sg
->length
+= pad_len
;
188 rq
->extra_len
+= pad_len
;
191 if (q
->dma_drain_size
&& q
->dma_drain_needed(rq
)) {
192 if (rq
->cmd_flags
& REQ_WRITE
)
193 memset(q
->dma_drain_buffer
, 0, q
->dma_drain_size
);
195 sg
->page_link
&= ~0x02;
197 sg_set_page(sg
, virt_to_page(q
->dma_drain_buffer
),
199 ((unsigned long)q
->dma_drain_buffer
) &
202 rq
->extra_len
+= q
->dma_drain_size
;
210 EXPORT_SYMBOL(blk_rq_map_sg
);
213 * blk_bio_map_sg - map a bio to a scatterlist
214 * @q: request_queue in question
215 * @bio: bio being mapped
216 * @sglist: scatterlist being mapped
219 * Caller must make sure sg can hold bio->bi_phys_segments entries
221 * Will return the number of sg entries setup
223 int blk_bio_map_sg(struct request_queue
*q
, struct bio
*bio
,
224 struct scatterlist
*sglist
)
226 struct bio_vec
*bvec
, *bvprv
;
227 struct scatterlist
*sg
;
232 cluster
= blk_queue_cluster(q
);
236 bio_for_each_segment(bvec
, bio
, i
) {
237 __blk_segment_map_sg(q
, bvec
, sglist
, &bvprv
, &sg
,
239 } /* segments in bio */
244 BUG_ON(bio
->bi_phys_segments
&& nsegs
> bio
->bi_phys_segments
);
247 EXPORT_SYMBOL(blk_bio_map_sg
);
249 static inline int ll_new_hw_segment(struct request_queue
*q
,
253 int nr_phys_segs
= bio_phys_segments(q
, bio
);
255 if (req
->nr_phys_segments
+ nr_phys_segs
> queue_max_segments(q
))
258 if (bio_integrity(bio
) && blk_integrity_merge_bio(q
, req
, bio
))
262 * This will form the start of a new hw segment. Bump both
265 req
->nr_phys_segments
+= nr_phys_segs
;
269 req
->cmd_flags
|= REQ_NOMERGE
;
270 if (req
== q
->last_merge
)
271 q
->last_merge
= NULL
;
275 int ll_back_merge_fn(struct request_queue
*q
, struct request
*req
,
278 if (blk_rq_sectors(req
) + bio_sectors(bio
) >
279 blk_rq_get_max_sectors(req
)) {
280 req
->cmd_flags
|= REQ_NOMERGE
;
281 if (req
== q
->last_merge
)
282 q
->last_merge
= NULL
;
285 if (!bio_flagged(req
->biotail
, BIO_SEG_VALID
))
286 blk_recount_segments(q
, req
->biotail
);
287 if (!bio_flagged(bio
, BIO_SEG_VALID
))
288 blk_recount_segments(q
, bio
);
290 return ll_new_hw_segment(q
, req
, bio
);
293 int ll_front_merge_fn(struct request_queue
*q
, struct request
*req
,
296 if (blk_rq_sectors(req
) + bio_sectors(bio
) >
297 blk_rq_get_max_sectors(req
)) {
298 req
->cmd_flags
|= REQ_NOMERGE
;
299 if (req
== q
->last_merge
)
300 q
->last_merge
= NULL
;
303 if (!bio_flagged(bio
, BIO_SEG_VALID
))
304 blk_recount_segments(q
, bio
);
305 if (!bio_flagged(req
->bio
, BIO_SEG_VALID
))
306 blk_recount_segments(q
, req
->bio
);
308 return ll_new_hw_segment(q
, req
, bio
);
311 static int ll_merge_requests_fn(struct request_queue
*q
, struct request
*req
,
312 struct request
*next
)
314 int total_phys_segments
;
315 unsigned int seg_size
=
316 req
->biotail
->bi_seg_back_size
+ next
->bio
->bi_seg_front_size
;
319 * First check if the either of the requests are re-queued
320 * requests. Can't merge them if they are.
322 if (req
->special
|| next
->special
)
326 * Will it become too large?
328 if ((blk_rq_sectors(req
) + blk_rq_sectors(next
)) >
329 blk_rq_get_max_sectors(req
))
332 total_phys_segments
= req
->nr_phys_segments
+ next
->nr_phys_segments
;
333 if (blk_phys_contig_segment(q
, req
->biotail
, next
->bio
)) {
334 if (req
->nr_phys_segments
== 1)
335 req
->bio
->bi_seg_front_size
= seg_size
;
336 if (next
->nr_phys_segments
== 1)
337 next
->biotail
->bi_seg_back_size
= seg_size
;
338 total_phys_segments
--;
341 if (total_phys_segments
> queue_max_segments(q
))
344 if (blk_integrity_rq(req
) && blk_integrity_merge_rq(q
, req
, next
))
348 req
->nr_phys_segments
= total_phys_segments
;
353 * blk_rq_set_mixed_merge - mark a request as mixed merge
354 * @rq: request to mark as mixed merge
357 * @rq is about to be mixed merged. Make sure the attributes
358 * which can be mixed are set in each bio and mark @rq as mixed
361 void blk_rq_set_mixed_merge(struct request
*rq
)
363 unsigned int ff
= rq
->cmd_flags
& REQ_FAILFAST_MASK
;
366 if (rq
->cmd_flags
& REQ_MIXED_MERGE
)
370 * @rq will no longer represent mixable attributes for all the
371 * contained bios. It will just track those of the first one.
372 * Distributes the attributs to each bio.
374 for (bio
= rq
->bio
; bio
; bio
= bio
->bi_next
) {
375 WARN_ON_ONCE((bio
->bi_rw
& REQ_FAILFAST_MASK
) &&
376 (bio
->bi_rw
& REQ_FAILFAST_MASK
) != ff
);
379 rq
->cmd_flags
|= REQ_MIXED_MERGE
;
382 static void blk_account_io_merge(struct request
*req
)
384 if (blk_do_io_stat(req
)) {
385 struct hd_struct
*part
;
388 cpu
= part_stat_lock();
391 part_round_stats(cpu
, part
);
392 part_dec_in_flight(part
, rq_data_dir(req
));
400 * Has to be called with the request spinlock acquired
402 static int attempt_merge(struct request_queue
*q
, struct request
*req
,
403 struct request
*next
)
405 if (!rq_mergeable(req
) || !rq_mergeable(next
))
408 if (!blk_check_merge_flags(req
->cmd_flags
, next
->cmd_flags
))
414 if (blk_rq_pos(req
) + blk_rq_sectors(req
) != blk_rq_pos(next
))
417 if (rq_data_dir(req
) != rq_data_dir(next
)
418 || req
->rq_disk
!= next
->rq_disk
422 if (req
->cmd_flags
& REQ_WRITE_SAME
&&
423 !blk_write_same_mergeable(req
->bio
, next
->bio
))
427 * If we are allowed to merge, then append bio list
428 * from next to rq and release next. merge_requests_fn
429 * will have updated segment counts, update sector
432 if (!ll_merge_requests_fn(q
, req
, next
))
436 * If failfast settings disagree or any of the two is already
437 * a mixed merge, mark both as mixed before proceeding. This
438 * makes sure that all involved bios have mixable attributes
441 if ((req
->cmd_flags
| next
->cmd_flags
) & REQ_MIXED_MERGE
||
442 (req
->cmd_flags
& REQ_FAILFAST_MASK
) !=
443 (next
->cmd_flags
& REQ_FAILFAST_MASK
)) {
444 blk_rq_set_mixed_merge(req
);
445 blk_rq_set_mixed_merge(next
);
449 * At this point we have either done a back merge
450 * or front merge. We need the smaller start_time of
451 * the merged requests to be the current request
452 * for accounting purposes.
454 if (time_after(req
->start_time
, next
->start_time
))
455 req
->start_time
= next
->start_time
;
457 req
->biotail
->bi_next
= next
->bio
;
458 req
->biotail
= next
->biotail
;
460 req
->__data_len
+= blk_rq_bytes(next
);
462 elv_merge_requests(q
, req
, next
);
465 * 'next' is going away, so update stats accordingly
467 blk_account_io_merge(next
);
469 req
->ioprio
= ioprio_best(req
->ioprio
, next
->ioprio
);
470 if (blk_rq_cpu_valid(next
))
471 req
->cpu
= next
->cpu
;
473 /* owner-ship of bio passed from next to req */
475 __blk_put_request(q
, next
);
479 int attempt_back_merge(struct request_queue
*q
, struct request
*rq
)
481 struct request
*next
= elv_latter_request(q
, rq
);
484 return attempt_merge(q
, rq
, next
);
489 int attempt_front_merge(struct request_queue
*q
, struct request
*rq
)
491 struct request
*prev
= elv_former_request(q
, rq
);
494 return attempt_merge(q
, prev
, rq
);
499 int blk_attempt_req_merge(struct request_queue
*q
, struct request
*rq
,
500 struct request
*next
)
502 return attempt_merge(q
, rq
, next
);
505 bool blk_rq_merge_ok(struct request
*rq
, struct bio
*bio
)
507 if (!rq_mergeable(rq
) || !bio_mergeable(bio
))
510 if (!blk_check_merge_flags(rq
->cmd_flags
, bio
->bi_rw
))
513 /* different data direction or already started, don't merge */
514 if (bio_data_dir(bio
) != rq_data_dir(rq
))
517 /* must be same device and not a special request */
518 if (rq
->rq_disk
!= bio
->bi_bdev
->bd_disk
|| rq
->special
)
521 /* only merge integrity protected bio into ditto rq */
522 if (bio_integrity(bio
) != blk_integrity_rq(rq
))
525 /* must be using the same buffer */
526 if (rq
->cmd_flags
& REQ_WRITE_SAME
&&
527 !blk_write_same_mergeable(rq
->bio
, bio
))
533 int blk_try_merge(struct request
*rq
, struct bio
*bio
)
535 if (blk_rq_pos(rq
) + blk_rq_sectors(rq
) == bio
->bi_sector
)
536 return ELEVATOR_BACK_MERGE
;
537 else if (blk_rq_pos(rq
) - bio_sectors(bio
) == bio
->bi_sector
)
538 return ELEVATOR_FRONT_MERGE
;
539 return ELEVATOR_NO_MERGE
;