Commit d6d48196961729b79509dcaeeb0f0fb4fbb47d29
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db1d08c646
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block: ll_rw_blk.c split, add blk-merge.c
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Showing 4 changed files with 495 additions and 481 deletions Side-by-side Diff
block/Makefile
| ... | ... | @@ -4,7 +4,7 @@ |
| 4 | 4 | |
| 5 | 5 | obj-$(CONFIG_BLOCK) := elevator.o blk-core.o blk-tag.o blk-sysfs.o \ |
| 6 | 6 | blk-barrier.o blk-settings.o blk-ioc.o blk-map.o \ |
| 7 | - blk-exec.o ioctl.o genhd.o scsi_ioctl.o | |
| 7 | + blk-exec.o blk-merge.o ioctl.o genhd.o scsi_ioctl.o | |
| 8 | 8 | |
| 9 | 9 | obj-$(CONFIG_BLK_DEV_BSG) += bsg.o |
| 10 | 10 | obj-$(CONFIG_IOSCHED_NOOP) += noop-iosched.o |
block/blk-core.c
| ... | ... | @@ -29,7 +29,6 @@ |
| 29 | 29 | #include <linux/cpu.h> |
| 30 | 30 | #include <linux/blktrace_api.h> |
| 31 | 31 | #include <linux/fault-inject.h> |
| 32 | -#include <linux/scatterlist.h> | |
| 33 | 32 | |
| 34 | 33 | #include "blk.h" |
| 35 | 34 | |
| 36 | 35 | |
| ... | ... | @@ -181,377 +180,7 @@ |
| 181 | 180 | |
| 182 | 181 | EXPORT_SYMBOL(blk_dump_rq_flags); |
| 183 | 182 | |
| 184 | -static void blk_recalc_rq_segments(struct request *rq) | |
| 185 | -{ | |
| 186 | - int nr_phys_segs; | |
| 187 | - int nr_hw_segs; | |
| 188 | - unsigned int phys_size; | |
| 189 | - unsigned int hw_size; | |
| 190 | - struct bio_vec *bv, *bvprv = NULL; | |
| 191 | - int seg_size; | |
| 192 | - int hw_seg_size; | |
| 193 | - int cluster; | |
| 194 | - struct req_iterator iter; | |
| 195 | - int high, highprv = 1; | |
| 196 | - struct request_queue *q = rq->q; | |
| 197 | - | |
| 198 | - if (!rq->bio) | |
| 199 | - return; | |
| 200 | - | |
| 201 | - cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER); | |
| 202 | - hw_seg_size = seg_size = 0; | |
| 203 | - phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0; | |
| 204 | - rq_for_each_segment(bv, rq, iter) { | |
| 205 | - /* | |
| 206 | - * the trick here is making sure that a high page is never | |
| 207 | - * considered part of another segment, since that might | |
| 208 | - * change with the bounce page. | |
| 209 | - */ | |
| 210 | - high = page_to_pfn(bv->bv_page) > q->bounce_pfn; | |
| 211 | - if (high || highprv) | |
| 212 | - goto new_hw_segment; | |
| 213 | - if (cluster) { | |
| 214 | - if (seg_size + bv->bv_len > q->max_segment_size) | |
| 215 | - goto new_segment; | |
| 216 | - if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv)) | |
| 217 | - goto new_segment; | |
| 218 | - if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv)) | |
| 219 | - goto new_segment; | |
| 220 | - if (BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len)) | |
| 221 | - goto new_hw_segment; | |
| 222 | - | |
| 223 | - seg_size += bv->bv_len; | |
| 224 | - hw_seg_size += bv->bv_len; | |
| 225 | - bvprv = bv; | |
| 226 | - continue; | |
| 227 | - } | |
| 228 | -new_segment: | |
| 229 | - if (BIOVEC_VIRT_MERGEABLE(bvprv, bv) && | |
| 230 | - !BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len)) | |
| 231 | - hw_seg_size += bv->bv_len; | |
| 232 | - else { | |
| 233 | -new_hw_segment: | |
| 234 | - if (nr_hw_segs == 1 && | |
| 235 | - hw_seg_size > rq->bio->bi_hw_front_size) | |
| 236 | - rq->bio->bi_hw_front_size = hw_seg_size; | |
| 237 | - hw_seg_size = BIOVEC_VIRT_START_SIZE(bv) + bv->bv_len; | |
| 238 | - nr_hw_segs++; | |
| 239 | - } | |
| 240 | - | |
| 241 | - nr_phys_segs++; | |
| 242 | - bvprv = bv; | |
| 243 | - seg_size = bv->bv_len; | |
| 244 | - highprv = high; | |
| 245 | - } | |
| 246 | - | |
| 247 | - if (nr_hw_segs == 1 && | |
| 248 | - hw_seg_size > rq->bio->bi_hw_front_size) | |
| 249 | - rq->bio->bi_hw_front_size = hw_seg_size; | |
| 250 | - if (hw_seg_size > rq->biotail->bi_hw_back_size) | |
| 251 | - rq->biotail->bi_hw_back_size = hw_seg_size; | |
| 252 | - rq->nr_phys_segments = nr_phys_segs; | |
| 253 | - rq->nr_hw_segments = nr_hw_segs; | |
| 254 | -} | |
| 255 | - | |
| 256 | -void blk_recount_segments(struct request_queue *q, struct bio *bio) | |
| 257 | -{ | |
| 258 | - struct request rq; | |
| 259 | - struct bio *nxt = bio->bi_next; | |
| 260 | - rq.q = q; | |
| 261 | - rq.bio = rq.biotail = bio; | |
| 262 | - bio->bi_next = NULL; | |
| 263 | - blk_recalc_rq_segments(&rq); | |
| 264 | - bio->bi_next = nxt; | |
| 265 | - bio->bi_phys_segments = rq.nr_phys_segments; | |
| 266 | - bio->bi_hw_segments = rq.nr_hw_segments; | |
| 267 | - bio->bi_flags |= (1 << BIO_SEG_VALID); | |
| 268 | -} | |
| 269 | -EXPORT_SYMBOL(blk_recount_segments); | |
| 270 | - | |
| 271 | -static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio, | |
| 272 | - struct bio *nxt) | |
| 273 | -{ | |
| 274 | - if (!(q->queue_flags & (1 << QUEUE_FLAG_CLUSTER))) | |
| 275 | - return 0; | |
| 276 | - | |
| 277 | - if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt))) | |
| 278 | - return 0; | |
| 279 | - if (bio->bi_size + nxt->bi_size > q->max_segment_size) | |
| 280 | - return 0; | |
| 281 | - | |
| 282 | - /* | |
| 283 | - * bio and nxt are contigous in memory, check if the queue allows | |
| 284 | - * these two to be merged into one | |
| 285 | - */ | |
| 286 | - if (BIO_SEG_BOUNDARY(q, bio, nxt)) | |
| 287 | - return 1; | |
| 288 | - | |
| 289 | - return 0; | |
| 290 | -} | |
| 291 | - | |
| 292 | -static int blk_hw_contig_segment(struct request_queue *q, struct bio *bio, | |
| 293 | - struct bio *nxt) | |
| 294 | -{ | |
| 295 | - if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) | |
| 296 | - blk_recount_segments(q, bio); | |
| 297 | - if (unlikely(!bio_flagged(nxt, BIO_SEG_VALID))) | |
| 298 | - blk_recount_segments(q, nxt); | |
| 299 | - if (!BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)) || | |
| 300 | - BIOVEC_VIRT_OVERSIZE(bio->bi_hw_back_size + nxt->bi_hw_front_size)) | |
| 301 | - return 0; | |
| 302 | - if (bio->bi_hw_back_size + nxt->bi_hw_front_size > q->max_segment_size) | |
| 303 | - return 0; | |
| 304 | - | |
| 305 | - return 1; | |
| 306 | -} | |
| 307 | - | |
| 308 | 183 | /* |
| 309 | - * map a request to scatterlist, return number of sg entries setup. Caller | |
| 310 | - * must make sure sg can hold rq->nr_phys_segments entries | |
| 311 | - */ | |
| 312 | -int blk_rq_map_sg(struct request_queue *q, struct request *rq, | |
| 313 | - struct scatterlist *sglist) | |
| 314 | -{ | |
| 315 | - struct bio_vec *bvec, *bvprv; | |
| 316 | - struct req_iterator iter; | |
| 317 | - struct scatterlist *sg; | |
| 318 | - int nsegs, cluster; | |
| 319 | - | |
| 320 | - nsegs = 0; | |
| 321 | - cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER); | |
| 322 | - | |
| 323 | - /* | |
| 324 | - * for each bio in rq | |
| 325 | - */ | |
| 326 | - bvprv = NULL; | |
| 327 | - sg = NULL; | |
| 328 | - rq_for_each_segment(bvec, rq, iter) { | |
| 329 | - int nbytes = bvec->bv_len; | |
| 330 | - | |
| 331 | - if (bvprv && cluster) { | |
| 332 | - if (sg->length + nbytes > q->max_segment_size) | |
| 333 | - goto new_segment; | |
| 334 | - | |
| 335 | - if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) | |
| 336 | - goto new_segment; | |
| 337 | - if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec)) | |
| 338 | - goto new_segment; | |
| 339 | - | |
| 340 | - sg->length += nbytes; | |
| 341 | - } else { | |
| 342 | -new_segment: | |
| 343 | - if (!sg) | |
| 344 | - sg = sglist; | |
| 345 | - else { | |
| 346 | - /* | |
| 347 | - * If the driver previously mapped a shorter | |
| 348 | - * list, we could see a termination bit | |
| 349 | - * prematurely unless it fully inits the sg | |
| 350 | - * table on each mapping. We KNOW that there | |
| 351 | - * must be more entries here or the driver | |
| 352 | - * would be buggy, so force clear the | |
| 353 | - * termination bit to avoid doing a full | |
| 354 | - * sg_init_table() in drivers for each command. | |
| 355 | - */ | |
| 356 | - sg->page_link &= ~0x02; | |
| 357 | - sg = sg_next(sg); | |
| 358 | - } | |
| 359 | - | |
| 360 | - sg_set_page(sg, bvec->bv_page, nbytes, bvec->bv_offset); | |
| 361 | - nsegs++; | |
| 362 | - } | |
| 363 | - bvprv = bvec; | |
| 364 | - } /* segments in rq */ | |
| 365 | - | |
| 366 | - if (q->dma_drain_size) { | |
| 367 | - sg->page_link &= ~0x02; | |
| 368 | - sg = sg_next(sg); | |
| 369 | - sg_set_page(sg, virt_to_page(q->dma_drain_buffer), | |
| 370 | - q->dma_drain_size, | |
| 371 | - ((unsigned long)q->dma_drain_buffer) & | |
| 372 | - (PAGE_SIZE - 1)); | |
| 373 | - nsegs++; | |
| 374 | - } | |
| 375 | - | |
| 376 | - if (sg) | |
| 377 | - sg_mark_end(sg); | |
| 378 | - | |
| 379 | - return nsegs; | |
| 380 | -} | |
| 381 | - | |
| 382 | -EXPORT_SYMBOL(blk_rq_map_sg); | |
| 383 | - | |
| 384 | -static inline int ll_new_mergeable(struct request_queue *q, | |
| 385 | - struct request *req, | |
| 386 | - struct bio *bio) | |
| 387 | -{ | |
| 388 | - int nr_phys_segs = bio_phys_segments(q, bio); | |
| 389 | - | |
| 390 | - if (req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) { | |
| 391 | - req->cmd_flags |= REQ_NOMERGE; | |
| 392 | - if (req == q->last_merge) | |
| 393 | - q->last_merge = NULL; | |
| 394 | - return 0; | |
| 395 | - } | |
| 396 | - | |
| 397 | - /* | |
| 398 | - * A hw segment is just getting larger, bump just the phys | |
| 399 | - * counter. | |
| 400 | - */ | |
| 401 | - req->nr_phys_segments += nr_phys_segs; | |
| 402 | - return 1; | |
| 403 | -} | |
| 404 | - | |
| 405 | -static inline int ll_new_hw_segment(struct request_queue *q, | |
| 406 | - struct request *req, | |
| 407 | - struct bio *bio) | |
| 408 | -{ | |
| 409 | - int nr_hw_segs = bio_hw_segments(q, bio); | |
| 410 | - int nr_phys_segs = bio_phys_segments(q, bio); | |
| 411 | - | |
| 412 | - if (req->nr_hw_segments + nr_hw_segs > q->max_hw_segments | |
| 413 | - || req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) { | |
| 414 | - req->cmd_flags |= REQ_NOMERGE; | |
| 415 | - if (req == q->last_merge) | |
| 416 | - q->last_merge = NULL; | |
| 417 | - return 0; | |
| 418 | - } | |
| 419 | - | |
| 420 | - /* | |
| 421 | - * This will form the start of a new hw segment. Bump both | |
| 422 | - * counters. | |
| 423 | - */ | |
| 424 | - req->nr_hw_segments += nr_hw_segs; | |
| 425 | - req->nr_phys_segments += nr_phys_segs; | |
| 426 | - return 1; | |
| 427 | -} | |
| 428 | - | |
| 429 | -int ll_back_merge_fn(struct request_queue *q, struct request *req, | |
| 430 | - struct bio *bio) | |
| 431 | -{ | |
| 432 | - unsigned short max_sectors; | |
| 433 | - int len; | |
| 434 | - | |
| 435 | - if (unlikely(blk_pc_request(req))) | |
| 436 | - max_sectors = q->max_hw_sectors; | |
| 437 | - else | |
| 438 | - max_sectors = q->max_sectors; | |
| 439 | - | |
| 440 | - if (req->nr_sectors + bio_sectors(bio) > max_sectors) { | |
| 441 | - req->cmd_flags |= REQ_NOMERGE; | |
| 442 | - if (req == q->last_merge) | |
| 443 | - q->last_merge = NULL; | |
| 444 | - return 0; | |
| 445 | - } | |
| 446 | - if (unlikely(!bio_flagged(req->biotail, BIO_SEG_VALID))) | |
| 447 | - blk_recount_segments(q, req->biotail); | |
| 448 | - if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) | |
| 449 | - blk_recount_segments(q, bio); | |
| 450 | - len = req->biotail->bi_hw_back_size + bio->bi_hw_front_size; | |
| 451 | - if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req->biotail), __BVEC_START(bio)) && | |
| 452 | - !BIOVEC_VIRT_OVERSIZE(len)) { | |
| 453 | - int mergeable = ll_new_mergeable(q, req, bio); | |
| 454 | - | |
| 455 | - if (mergeable) { | |
| 456 | - if (req->nr_hw_segments == 1) | |
| 457 | - req->bio->bi_hw_front_size = len; | |
| 458 | - if (bio->bi_hw_segments == 1) | |
| 459 | - bio->bi_hw_back_size = len; | |
| 460 | - } | |
| 461 | - return mergeable; | |
| 462 | - } | |
| 463 | - | |
| 464 | - return ll_new_hw_segment(q, req, bio); | |
| 465 | -} | |
| 466 | - | |
| 467 | -static int ll_front_merge_fn(struct request_queue *q, struct request *req, | |
| 468 | - struct bio *bio) | |
| 469 | -{ | |
| 470 | - unsigned short max_sectors; | |
| 471 | - int len; | |
| 472 | - | |
| 473 | - if (unlikely(blk_pc_request(req))) | |
| 474 | - max_sectors = q->max_hw_sectors; | |
| 475 | - else | |
| 476 | - max_sectors = q->max_sectors; | |
| 477 | - | |
| 478 | - | |
| 479 | - if (req->nr_sectors + bio_sectors(bio) > max_sectors) { | |
| 480 | - req->cmd_flags |= REQ_NOMERGE; | |
| 481 | - if (req == q->last_merge) | |
| 482 | - q->last_merge = NULL; | |
| 483 | - return 0; | |
| 484 | - } | |
| 485 | - len = bio->bi_hw_back_size + req->bio->bi_hw_front_size; | |
| 486 | - if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) | |
| 487 | - blk_recount_segments(q, bio); | |
| 488 | - if (unlikely(!bio_flagged(req->bio, BIO_SEG_VALID))) | |
| 489 | - blk_recount_segments(q, req->bio); | |
| 490 | - if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(req->bio)) && | |
| 491 | - !BIOVEC_VIRT_OVERSIZE(len)) { | |
| 492 | - int mergeable = ll_new_mergeable(q, req, bio); | |
| 493 | - | |
| 494 | - if (mergeable) { | |
| 495 | - if (bio->bi_hw_segments == 1) | |
| 496 | - bio->bi_hw_front_size = len; | |
| 497 | - if (req->nr_hw_segments == 1) | |
| 498 | - req->biotail->bi_hw_back_size = len; | |
| 499 | - } | |
| 500 | - return mergeable; | |
| 501 | - } | |
| 502 | - | |
| 503 | - return ll_new_hw_segment(q, req, bio); | |
| 504 | -} | |
| 505 | - | |
| 506 | -static int ll_merge_requests_fn(struct request_queue *q, struct request *req, | |
| 507 | - struct request *next) | |
| 508 | -{ | |
| 509 | - int total_phys_segments; | |
| 510 | - int total_hw_segments; | |
| 511 | - | |
| 512 | - /* | |
| 513 | - * First check if the either of the requests are re-queued | |
| 514 | - * requests. Can't merge them if they are. | |
| 515 | - */ | |
| 516 | - if (req->special || next->special) | |
| 517 | - return 0; | |
| 518 | - | |
| 519 | - /* | |
| 520 | - * Will it become too large? | |
| 521 | - */ | |
| 522 | - if ((req->nr_sectors + next->nr_sectors) > q->max_sectors) | |
| 523 | - return 0; | |
| 524 | - | |
| 525 | - total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; | |
| 526 | - if (blk_phys_contig_segment(q, req->biotail, next->bio)) | |
| 527 | - total_phys_segments--; | |
| 528 | - | |
| 529 | - if (total_phys_segments > q->max_phys_segments) | |
| 530 | - return 0; | |
| 531 | - | |
| 532 | - total_hw_segments = req->nr_hw_segments + next->nr_hw_segments; | |
| 533 | - if (blk_hw_contig_segment(q, req->biotail, next->bio)) { | |
| 534 | - int len = req->biotail->bi_hw_back_size + next->bio->bi_hw_front_size; | |
| 535 | - /* | |
| 536 | - * propagate the combined length to the end of the requests | |
| 537 | - */ | |
| 538 | - if (req->nr_hw_segments == 1) | |
| 539 | - req->bio->bi_hw_front_size = len; | |
| 540 | - if (next->nr_hw_segments == 1) | |
| 541 | - next->biotail->bi_hw_back_size = len; | |
| 542 | - total_hw_segments--; | |
| 543 | - } | |
| 544 | - | |
| 545 | - if (total_hw_segments > q->max_hw_segments) | |
| 546 | - return 0; | |
| 547 | - | |
| 548 | - /* Merge is OK... */ | |
| 549 | - req->nr_phys_segments = total_phys_segments; | |
| 550 | - req->nr_hw_segments = total_hw_segments; | |
| 551 | - return 1; | |
| 552 | -} | |
| 553 | - | |
| 554 | -/* | |
| 555 | 184 | * "plug" the device if there are no outstanding requests: this will |
| 556 | 185 | * force the transfer to start only after we have put all the requests |
| 557 | 186 | * on the list. |
| ... | ... | @@ -1409,84 +1038,6 @@ |
| 1409 | 1038 | |
| 1410 | 1039 | EXPORT_SYMBOL(blk_put_request); |
| 1411 | 1040 | |
| 1412 | -/* | |
| 1413 | - * Has to be called with the request spinlock acquired | |
| 1414 | - */ | |
| 1415 | -static int attempt_merge(struct request_queue *q, struct request *req, | |
| 1416 | - struct request *next) | |
| 1417 | -{ | |
| 1418 | - if (!rq_mergeable(req) || !rq_mergeable(next)) | |
| 1419 | - return 0; | |
| 1420 | - | |
| 1421 | - /* | |
| 1422 | - * not contiguous | |
| 1423 | - */ | |
| 1424 | - if (req->sector + req->nr_sectors != next->sector) | |
| 1425 | - return 0; | |
| 1426 | - | |
| 1427 | - if (rq_data_dir(req) != rq_data_dir(next) | |
| 1428 | - || req->rq_disk != next->rq_disk | |
| 1429 | - || next->special) | |
| 1430 | - return 0; | |
| 1431 | - | |
| 1432 | - /* | |
| 1433 | - * If we are allowed to merge, then append bio list | |
| 1434 | - * from next to rq and release next. merge_requests_fn | |
| 1435 | - * will have updated segment counts, update sector | |
| 1436 | - * counts here. | |
| 1437 | - */ | |
| 1438 | - if (!ll_merge_requests_fn(q, req, next)) | |
| 1439 | - return 0; | |
| 1440 | - | |
| 1441 | - /* | |
| 1442 | - * At this point we have either done a back merge | |
| 1443 | - * or front merge. We need the smaller start_time of | |
| 1444 | - * the merged requests to be the current request | |
| 1445 | - * for accounting purposes. | |
| 1446 | - */ | |
| 1447 | - if (time_after(req->start_time, next->start_time)) | |
| 1448 | - req->start_time = next->start_time; | |
| 1449 | - | |
| 1450 | - req->biotail->bi_next = next->bio; | |
| 1451 | - req->biotail = next->biotail; | |
| 1452 | - | |
| 1453 | - req->nr_sectors = req->hard_nr_sectors += next->hard_nr_sectors; | |
| 1454 | - | |
| 1455 | - elv_merge_requests(q, req, next); | |
| 1456 | - | |
| 1457 | - if (req->rq_disk) { | |
| 1458 | - disk_round_stats(req->rq_disk); | |
| 1459 | - req->rq_disk->in_flight--; | |
| 1460 | - } | |
| 1461 | - | |
| 1462 | - req->ioprio = ioprio_best(req->ioprio, next->ioprio); | |
| 1463 | - | |
| 1464 | - __blk_put_request(q, next); | |
| 1465 | - return 1; | |
| 1466 | -} | |
| 1467 | - | |
| 1468 | -static inline int attempt_back_merge(struct request_queue *q, | |
| 1469 | - struct request *rq) | |
| 1470 | -{ | |
| 1471 | - struct request *next = elv_latter_request(q, rq); | |
| 1472 | - | |
| 1473 | - if (next) | |
| 1474 | - return attempt_merge(q, rq, next); | |
| 1475 | - | |
| 1476 | - return 0; | |
| 1477 | -} | |
| 1478 | - | |
| 1479 | -static inline int attempt_front_merge(struct request_queue *q, | |
| 1480 | - struct request *rq) | |
| 1481 | -{ | |
| 1482 | - struct request *prev = elv_former_request(q, rq); | |
| 1483 | - | |
| 1484 | - if (prev) | |
| 1485 | - return attempt_merge(q, prev, rq); | |
| 1486 | - | |
| 1487 | - return 0; | |
| 1488 | -} | |
| 1489 | - | |
| 1490 | 1041 | void init_request_from_bio(struct request *req, struct bio *bio) |
| 1491 | 1042 | { |
| 1492 | 1043 | req->cmd_type = REQ_TYPE_FS; |
| ... | ... | @@ -1937,35 +1488,6 @@ |
| 1937 | 1488 | } |
| 1938 | 1489 | |
| 1939 | 1490 | EXPORT_SYMBOL(submit_bio); |
| 1940 | - | |
| 1941 | -static void blk_recalc_rq_sectors(struct request *rq, int nsect) | |
| 1942 | -{ | |
| 1943 | - if (blk_fs_request(rq)) { | |
| 1944 | - rq->hard_sector += nsect; | |
| 1945 | - rq->hard_nr_sectors -= nsect; | |
| 1946 | - | |
| 1947 | - /* | |
| 1948 | - * Move the I/O submission pointers ahead if required. | |
| 1949 | - */ | |
| 1950 | - if ((rq->nr_sectors >= rq->hard_nr_sectors) && | |
| 1951 | - (rq->sector <= rq->hard_sector)) { | |
| 1952 | - rq->sector = rq->hard_sector; | |
| 1953 | - rq->nr_sectors = rq->hard_nr_sectors; | |
| 1954 | - rq->hard_cur_sectors = bio_cur_sectors(rq->bio); | |
| 1955 | - rq->current_nr_sectors = rq->hard_cur_sectors; | |
| 1956 | - rq->buffer = bio_data(rq->bio); | |
| 1957 | - } | |
| 1958 | - | |
| 1959 | - /* | |
| 1960 | - * if total number of sectors is less than the first segment | |
| 1961 | - * size, something has gone terribly wrong | |
| 1962 | - */ | |
| 1963 | - if (rq->nr_sectors < rq->current_nr_sectors) { | |
| 1964 | - printk("blk: request botched\n"); | |
| 1965 | - rq->nr_sectors = rq->current_nr_sectors; | |
| 1966 | - } | |
| 1967 | - } | |
| 1968 | -} | |
| 1969 | 1491 | |
| 1970 | 1492 | /** |
| 1971 | 1493 | * __end_that_request_first - end I/O on a request |
block/blk-merge.c
| 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 | + | |
| 12 | +void blk_recalc_rq_sectors(struct request *rq, int nsect) | |
| 13 | +{ | |
| 14 | + if (blk_fs_request(rq)) { | |
| 15 | + rq->hard_sector += nsect; | |
| 16 | + rq->hard_nr_sectors -= nsect; | |
| 17 | + | |
| 18 | + /* | |
| 19 | + * Move the I/O submission pointers ahead if required. | |
| 20 | + */ | |
| 21 | + if ((rq->nr_sectors >= rq->hard_nr_sectors) && | |
| 22 | + (rq->sector <= rq->hard_sector)) { | |
| 23 | + rq->sector = rq->hard_sector; | |
| 24 | + rq->nr_sectors = rq->hard_nr_sectors; | |
| 25 | + rq->hard_cur_sectors = bio_cur_sectors(rq->bio); | |
| 26 | + rq->current_nr_sectors = rq->hard_cur_sectors; | |
| 27 | + rq->buffer = bio_data(rq->bio); | |
| 28 | + } | |
| 29 | + | |
| 30 | + /* | |
| 31 | + * if total number of sectors is less than the first segment | |
| 32 | + * size, something has gone terribly wrong | |
| 33 | + */ | |
| 34 | + if (rq->nr_sectors < rq->current_nr_sectors) { | |
| 35 | + printk("blk: request botched\n"); | |
| 36 | + rq->nr_sectors = rq->current_nr_sectors; | |
| 37 | + } | |
| 38 | + } | |
| 39 | +} | |
| 40 | + | |
| 41 | +void blk_recalc_rq_segments(struct request *rq) | |
| 42 | +{ | |
| 43 | + int nr_phys_segs; | |
| 44 | + int nr_hw_segs; | |
| 45 | + unsigned int phys_size; | |
| 46 | + unsigned int hw_size; | |
| 47 | + struct bio_vec *bv, *bvprv = NULL; | |
| 48 | + int seg_size; | |
| 49 | + int hw_seg_size; | |
| 50 | + int cluster; | |
| 51 | + struct req_iterator iter; | |
| 52 | + int high, highprv = 1; | |
| 53 | + struct request_queue *q = rq->q; | |
| 54 | + | |
| 55 | + if (!rq->bio) | |
| 56 | + return; | |
| 57 | + | |
| 58 | + cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER); | |
| 59 | + hw_seg_size = seg_size = 0; | |
| 60 | + phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0; | |
| 61 | + rq_for_each_segment(bv, rq, iter) { | |
| 62 | + /* | |
| 63 | + * the trick here is making sure that a high page is never | |
| 64 | + * considered part of another segment, since that might | |
| 65 | + * change with the bounce page. | |
| 66 | + */ | |
| 67 | + high = page_to_pfn(bv->bv_page) > q->bounce_pfn; | |
| 68 | + if (high || highprv) | |
| 69 | + goto new_hw_segment; | |
| 70 | + if (cluster) { | |
| 71 | + if (seg_size + bv->bv_len > q->max_segment_size) | |
| 72 | + goto new_segment; | |
| 73 | + if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv)) | |
| 74 | + goto new_segment; | |
| 75 | + if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv)) | |
| 76 | + goto new_segment; | |
| 77 | + if (BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len)) | |
| 78 | + goto new_hw_segment; | |
| 79 | + | |
| 80 | + seg_size += bv->bv_len; | |
| 81 | + hw_seg_size += bv->bv_len; | |
| 82 | + bvprv = bv; | |
| 83 | + continue; | |
| 84 | + } | |
| 85 | +new_segment: | |
| 86 | + if (BIOVEC_VIRT_MERGEABLE(bvprv, bv) && | |
| 87 | + !BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len)) | |
| 88 | + hw_seg_size += bv->bv_len; | |
| 89 | + else { | |
| 90 | +new_hw_segment: | |
| 91 | + if (nr_hw_segs == 1 && | |
| 92 | + hw_seg_size > rq->bio->bi_hw_front_size) | |
| 93 | + rq->bio->bi_hw_front_size = hw_seg_size; | |
| 94 | + hw_seg_size = BIOVEC_VIRT_START_SIZE(bv) + bv->bv_len; | |
| 95 | + nr_hw_segs++; | |
| 96 | + } | |
| 97 | + | |
| 98 | + nr_phys_segs++; | |
| 99 | + bvprv = bv; | |
| 100 | + seg_size = bv->bv_len; | |
| 101 | + highprv = high; | |
| 102 | + } | |
| 103 | + | |
| 104 | + if (nr_hw_segs == 1 && | |
| 105 | + hw_seg_size > rq->bio->bi_hw_front_size) | |
| 106 | + rq->bio->bi_hw_front_size = hw_seg_size; | |
| 107 | + if (hw_seg_size > rq->biotail->bi_hw_back_size) | |
| 108 | + rq->biotail->bi_hw_back_size = hw_seg_size; | |
| 109 | + rq->nr_phys_segments = nr_phys_segs; | |
| 110 | + rq->nr_hw_segments = nr_hw_segs; | |
| 111 | +} | |
| 112 | + | |
| 113 | +void blk_recount_segments(struct request_queue *q, struct bio *bio) | |
| 114 | +{ | |
| 115 | + struct request rq; | |
| 116 | + struct bio *nxt = bio->bi_next; | |
| 117 | + rq.q = q; | |
| 118 | + rq.bio = rq.biotail = bio; | |
| 119 | + bio->bi_next = NULL; | |
| 120 | + blk_recalc_rq_segments(&rq); | |
| 121 | + bio->bi_next = nxt; | |
| 122 | + bio->bi_phys_segments = rq.nr_phys_segments; | |
| 123 | + bio->bi_hw_segments = rq.nr_hw_segments; | |
| 124 | + bio->bi_flags |= (1 << BIO_SEG_VALID); | |
| 125 | +} | |
| 126 | +EXPORT_SYMBOL(blk_recount_segments); | |
| 127 | + | |
| 128 | +static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio, | |
| 129 | + struct bio *nxt) | |
| 130 | +{ | |
| 131 | + if (!(q->queue_flags & (1 << QUEUE_FLAG_CLUSTER))) | |
| 132 | + return 0; | |
| 133 | + | |
| 134 | + if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt))) | |
| 135 | + return 0; | |
| 136 | + if (bio->bi_size + nxt->bi_size > q->max_segment_size) | |
| 137 | + return 0; | |
| 138 | + | |
| 139 | + /* | |
| 140 | + * bio and nxt are contigous in memory, check if the queue allows | |
| 141 | + * these two to be merged into one | |
| 142 | + */ | |
| 143 | + if (BIO_SEG_BOUNDARY(q, bio, nxt)) | |
| 144 | + return 1; | |
| 145 | + | |
| 146 | + return 0; | |
| 147 | +} | |
| 148 | + | |
| 149 | +static int blk_hw_contig_segment(struct request_queue *q, struct bio *bio, | |
| 150 | + struct bio *nxt) | |
| 151 | +{ | |
| 152 | + if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) | |
| 153 | + blk_recount_segments(q, bio); | |
| 154 | + if (unlikely(!bio_flagged(nxt, BIO_SEG_VALID))) | |
| 155 | + blk_recount_segments(q, nxt); | |
| 156 | + if (!BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)) || | |
| 157 | + BIOVEC_VIRT_OVERSIZE(bio->bi_hw_back_size + nxt->bi_hw_front_size)) | |
| 158 | + return 0; | |
| 159 | + if (bio->bi_hw_back_size + nxt->bi_hw_front_size > q->max_segment_size) | |
| 160 | + return 0; | |
| 161 | + | |
| 162 | + return 1; | |
| 163 | +} | |
| 164 | + | |
| 165 | +/* | |
| 166 | + * map a request to scatterlist, return number of sg entries setup. Caller | |
| 167 | + * must make sure sg can hold rq->nr_phys_segments entries | |
| 168 | + */ | |
| 169 | +int blk_rq_map_sg(struct request_queue *q, struct request *rq, | |
| 170 | + struct scatterlist *sglist) | |
| 171 | +{ | |
| 172 | + struct bio_vec *bvec, *bvprv; | |
| 173 | + struct req_iterator iter; | |
| 174 | + struct scatterlist *sg; | |
| 175 | + int nsegs, cluster; | |
| 176 | + | |
| 177 | + nsegs = 0; | |
| 178 | + cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER); | |
| 179 | + | |
| 180 | + /* | |
| 181 | + * for each bio in rq | |
| 182 | + */ | |
| 183 | + bvprv = NULL; | |
| 184 | + sg = NULL; | |
| 185 | + rq_for_each_segment(bvec, rq, iter) { | |
| 186 | + int nbytes = bvec->bv_len; | |
| 187 | + | |
| 188 | + if (bvprv && cluster) { | |
| 189 | + if (sg->length + nbytes > q->max_segment_size) | |
| 190 | + goto new_segment; | |
| 191 | + | |
| 192 | + if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) | |
| 193 | + goto new_segment; | |
| 194 | + if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec)) | |
| 195 | + goto new_segment; | |
| 196 | + | |
| 197 | + sg->length += nbytes; | |
| 198 | + } else { | |
| 199 | +new_segment: | |
| 200 | + if (!sg) | |
| 201 | + sg = sglist; | |
| 202 | + else { | |
| 203 | + /* | |
| 204 | + * If the driver previously mapped a shorter | |
| 205 | + * list, we could see a termination bit | |
| 206 | + * prematurely unless it fully inits the sg | |
| 207 | + * table on each mapping. We KNOW that there | |
| 208 | + * must be more entries here or the driver | |
| 209 | + * would be buggy, so force clear the | |
| 210 | + * termination bit to avoid doing a full | |
| 211 | + * sg_init_table() in drivers for each command. | |
| 212 | + */ | |
| 213 | + sg->page_link &= ~0x02; | |
| 214 | + sg = sg_next(sg); | |
| 215 | + } | |
| 216 | + | |
| 217 | + sg_set_page(sg, bvec->bv_page, nbytes, bvec->bv_offset); | |
| 218 | + nsegs++; | |
| 219 | + } | |
| 220 | + bvprv = bvec; | |
| 221 | + } /* segments in rq */ | |
| 222 | + | |
| 223 | + if (q->dma_drain_size) { | |
| 224 | + sg->page_link &= ~0x02; | |
| 225 | + sg = sg_next(sg); | |
| 226 | + sg_set_page(sg, virt_to_page(q->dma_drain_buffer), | |
| 227 | + q->dma_drain_size, | |
| 228 | + ((unsigned long)q->dma_drain_buffer) & | |
| 229 | + (PAGE_SIZE - 1)); | |
| 230 | + nsegs++; | |
| 231 | + } | |
| 232 | + | |
| 233 | + if (sg) | |
| 234 | + sg_mark_end(sg); | |
| 235 | + | |
| 236 | + return nsegs; | |
| 237 | +} | |
| 238 | + | |
| 239 | +EXPORT_SYMBOL(blk_rq_map_sg); | |
| 240 | + | |
| 241 | +static inline int ll_new_mergeable(struct request_queue *q, | |
| 242 | + struct request *req, | |
| 243 | + struct bio *bio) | |
| 244 | +{ | |
| 245 | + int nr_phys_segs = bio_phys_segments(q, bio); | |
| 246 | + | |
| 247 | + if (req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) { | |
| 248 | + req->cmd_flags |= REQ_NOMERGE; | |
| 249 | + if (req == q->last_merge) | |
| 250 | + q->last_merge = NULL; | |
| 251 | + return 0; | |
| 252 | + } | |
| 253 | + | |
| 254 | + /* | |
| 255 | + * A hw segment is just getting larger, bump just the phys | |
| 256 | + * counter. | |
| 257 | + */ | |
| 258 | + req->nr_phys_segments += nr_phys_segs; | |
| 259 | + return 1; | |
| 260 | +} | |
| 261 | + | |
| 262 | +static inline int ll_new_hw_segment(struct request_queue *q, | |
| 263 | + struct request *req, | |
| 264 | + struct bio *bio) | |
| 265 | +{ | |
| 266 | + int nr_hw_segs = bio_hw_segments(q, bio); | |
| 267 | + int nr_phys_segs = bio_phys_segments(q, bio); | |
| 268 | + | |
| 269 | + if (req->nr_hw_segments + nr_hw_segs > q->max_hw_segments | |
| 270 | + || req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) { | |
| 271 | + req->cmd_flags |= REQ_NOMERGE; | |
| 272 | + if (req == q->last_merge) | |
| 273 | + q->last_merge = NULL; | |
| 274 | + return 0; | |
| 275 | + } | |
| 276 | + | |
| 277 | + /* | |
| 278 | + * This will form the start of a new hw segment. Bump both | |
| 279 | + * counters. | |
| 280 | + */ | |
| 281 | + req->nr_hw_segments += nr_hw_segs; | |
| 282 | + req->nr_phys_segments += nr_phys_segs; | |
| 283 | + return 1; | |
| 284 | +} | |
| 285 | + | |
| 286 | +int ll_back_merge_fn(struct request_queue *q, struct request *req, | |
| 287 | + struct bio *bio) | |
| 288 | +{ | |
| 289 | + unsigned short max_sectors; | |
| 290 | + int len; | |
| 291 | + | |
| 292 | + if (unlikely(blk_pc_request(req))) | |
| 293 | + max_sectors = q->max_hw_sectors; | |
| 294 | + else | |
| 295 | + max_sectors = q->max_sectors; | |
| 296 | + | |
| 297 | + if (req->nr_sectors + bio_sectors(bio) > max_sectors) { | |
| 298 | + req->cmd_flags |= REQ_NOMERGE; | |
| 299 | + if (req == q->last_merge) | |
| 300 | + q->last_merge = NULL; | |
| 301 | + return 0; | |
| 302 | + } | |
| 303 | + if (unlikely(!bio_flagged(req->biotail, BIO_SEG_VALID))) | |
| 304 | + blk_recount_segments(q, req->biotail); | |
| 305 | + if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) | |
| 306 | + blk_recount_segments(q, bio); | |
| 307 | + len = req->biotail->bi_hw_back_size + bio->bi_hw_front_size; | |
| 308 | + if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req->biotail), __BVEC_START(bio)) && | |
| 309 | + !BIOVEC_VIRT_OVERSIZE(len)) { | |
| 310 | + int mergeable = ll_new_mergeable(q, req, bio); | |
| 311 | + | |
| 312 | + if (mergeable) { | |
| 313 | + if (req->nr_hw_segments == 1) | |
| 314 | + req->bio->bi_hw_front_size = len; | |
| 315 | + if (bio->bi_hw_segments == 1) | |
| 316 | + bio->bi_hw_back_size = len; | |
| 317 | + } | |
| 318 | + return mergeable; | |
| 319 | + } | |
| 320 | + | |
| 321 | + return ll_new_hw_segment(q, req, bio); | |
| 322 | +} | |
| 323 | + | |
| 324 | +int ll_front_merge_fn(struct request_queue *q, struct request *req, | |
| 325 | + struct bio *bio) | |
| 326 | +{ | |
| 327 | + unsigned short max_sectors; | |
| 328 | + int len; | |
| 329 | + | |
| 330 | + if (unlikely(blk_pc_request(req))) | |
| 331 | + max_sectors = q->max_hw_sectors; | |
| 332 | + else | |
| 333 | + max_sectors = q->max_sectors; | |
| 334 | + | |
| 335 | + | |
| 336 | + if (req->nr_sectors + bio_sectors(bio) > max_sectors) { | |
| 337 | + req->cmd_flags |= REQ_NOMERGE; | |
| 338 | + if (req == q->last_merge) | |
| 339 | + q->last_merge = NULL; | |
| 340 | + return 0; | |
| 341 | + } | |
| 342 | + len = bio->bi_hw_back_size + req->bio->bi_hw_front_size; | |
| 343 | + if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) | |
| 344 | + blk_recount_segments(q, bio); | |
| 345 | + if (unlikely(!bio_flagged(req->bio, BIO_SEG_VALID))) | |
| 346 | + blk_recount_segments(q, req->bio); | |
| 347 | + if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(req->bio)) && | |
| 348 | + !BIOVEC_VIRT_OVERSIZE(len)) { | |
| 349 | + int mergeable = ll_new_mergeable(q, req, bio); | |
| 350 | + | |
| 351 | + if (mergeable) { | |
| 352 | + if (bio->bi_hw_segments == 1) | |
| 353 | + bio->bi_hw_front_size = len; | |
| 354 | + if (req->nr_hw_segments == 1) | |
| 355 | + req->biotail->bi_hw_back_size = len; | |
| 356 | + } | |
| 357 | + return mergeable; | |
| 358 | + } | |
| 359 | + | |
| 360 | + return ll_new_hw_segment(q, req, bio); | |
| 361 | +} | |
| 362 | + | |
| 363 | +static int ll_merge_requests_fn(struct request_queue *q, struct request *req, | |
| 364 | + struct request *next) | |
| 365 | +{ | |
| 366 | + int total_phys_segments; | |
| 367 | + int total_hw_segments; | |
| 368 | + | |
| 369 | + /* | |
| 370 | + * First check if the either of the requests are re-queued | |
| 371 | + * requests. Can't merge them if they are. | |
| 372 | + */ | |
| 373 | + if (req->special || next->special) | |
| 374 | + return 0; | |
| 375 | + | |
| 376 | + /* | |
| 377 | + * Will it become too large? | |
| 378 | + */ | |
| 379 | + if ((req->nr_sectors + next->nr_sectors) > q->max_sectors) | |
| 380 | + return 0; | |
| 381 | + | |
| 382 | + total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; | |
| 383 | + if (blk_phys_contig_segment(q, req->biotail, next->bio)) | |
| 384 | + total_phys_segments--; | |
| 385 | + | |
| 386 | + if (total_phys_segments > q->max_phys_segments) | |
| 387 | + return 0; | |
| 388 | + | |
| 389 | + total_hw_segments = req->nr_hw_segments + next->nr_hw_segments; | |
| 390 | + if (blk_hw_contig_segment(q, req->biotail, next->bio)) { | |
| 391 | + int len = req->biotail->bi_hw_back_size + next->bio->bi_hw_front_size; | |
| 392 | + /* | |
| 393 | + * propagate the combined length to the end of the requests | |
| 394 | + */ | |
| 395 | + if (req->nr_hw_segments == 1) | |
| 396 | + req->bio->bi_hw_front_size = len; | |
| 397 | + if (next->nr_hw_segments == 1) | |
| 398 | + next->biotail->bi_hw_back_size = len; | |
| 399 | + total_hw_segments--; | |
| 400 | + } | |
| 401 | + | |
| 402 | + if (total_hw_segments > q->max_hw_segments) | |
| 403 | + return 0; | |
| 404 | + | |
| 405 | + /* Merge is OK... */ | |
| 406 | + req->nr_phys_segments = total_phys_segments; | |
| 407 | + req->nr_hw_segments = total_hw_segments; | |
| 408 | + return 1; | |
| 409 | +} | |
| 410 | + | |
| 411 | +/* | |
| 412 | + * Has to be called with the request spinlock acquired | |
| 413 | + */ | |
| 414 | +static int attempt_merge(struct request_queue *q, struct request *req, | |
| 415 | + struct request *next) | |
| 416 | +{ | |
| 417 | + if (!rq_mergeable(req) || !rq_mergeable(next)) | |
| 418 | + return 0; | |
| 419 | + | |
| 420 | + /* | |
| 421 | + * not contiguous | |
| 422 | + */ | |
| 423 | + if (req->sector + req->nr_sectors != next->sector) | |
| 424 | + return 0; | |
| 425 | + | |
| 426 | + if (rq_data_dir(req) != rq_data_dir(next) | |
| 427 | + || req->rq_disk != next->rq_disk | |
| 428 | + || next->special) | |
| 429 | + return 0; | |
| 430 | + | |
| 431 | + /* | |
| 432 | + * If we are allowed to merge, then append bio list | |
| 433 | + * from next to rq and release next. merge_requests_fn | |
| 434 | + * will have updated segment counts, update sector | |
| 435 | + * counts here. | |
| 436 | + */ | |
| 437 | + if (!ll_merge_requests_fn(q, req, next)) | |
| 438 | + return 0; | |
| 439 | + | |
| 440 | + /* | |
| 441 | + * At this point we have either done a back merge | |
| 442 | + * or front merge. We need the smaller start_time of | |
| 443 | + * the merged requests to be the current request | |
| 444 | + * for accounting purposes. | |
| 445 | + */ | |
| 446 | + if (time_after(req->start_time, next->start_time)) | |
| 447 | + req->start_time = next->start_time; | |
| 448 | + | |
| 449 | + req->biotail->bi_next = next->bio; | |
| 450 | + req->biotail = next->biotail; | |
| 451 | + | |
| 452 | + req->nr_sectors = req->hard_nr_sectors += next->hard_nr_sectors; | |
| 453 | + | |
| 454 | + elv_merge_requests(q, req, next); | |
| 455 | + | |
| 456 | + if (req->rq_disk) { | |
| 457 | + disk_round_stats(req->rq_disk); | |
| 458 | + req->rq_disk->in_flight--; | |
| 459 | + } | |
| 460 | + | |
| 461 | + req->ioprio = ioprio_best(req->ioprio, next->ioprio); | |
| 462 | + | |
| 463 | + __blk_put_request(q, next); | |
| 464 | + return 1; | |
| 465 | +} | |
| 466 | + | |
| 467 | +int attempt_back_merge(struct request_queue *q, struct request *rq) | |
| 468 | +{ | |
| 469 | + struct request *next = elv_latter_request(q, rq); | |
| 470 | + | |
| 471 | + if (next) | |
| 472 | + return attempt_merge(q, rq, next); | |
| 473 | + | |
| 474 | + return 0; | |
| 475 | +} | |
| 476 | + | |
| 477 | +int attempt_front_merge(struct request_queue *q, struct request *rq) | |
| 478 | +{ | |
| 479 | + struct request *prev = elv_former_request(q, rq); | |
| 480 | + | |
| 481 | + if (prev) | |
| 482 | + return attempt_merge(q, prev, rq); | |
| 483 | + | |
| 484 | + return 0; | |
| 485 | +} |
block/blk.h
| ... | ... | @@ -14,14 +14,21 @@ |
| 14 | 14 | void init_request_from_bio(struct request *req, struct bio *bio); |
| 15 | 15 | void blk_rq_bio_prep(struct request_queue *q, struct request *rq, |
| 16 | 16 | struct bio *bio); |
| 17 | -int ll_back_merge_fn(struct request_queue *q, struct request *req, | |
| 18 | - struct bio *bio); | |
| 19 | 17 | void __blk_queue_free_tags(struct request_queue *q); |
| 20 | 18 | |
| 21 | 19 | void blk_unplug_work(struct work_struct *work); |
| 22 | 20 | void blk_unplug_timeout(unsigned long data); |
| 23 | 21 | |
| 24 | 22 | struct io_context *current_io_context(gfp_t gfp_flags, int node); |
| 23 | + | |
| 24 | +int ll_back_merge_fn(struct request_queue *q, struct request *req, | |
| 25 | + struct bio *bio); | |
| 26 | +int ll_front_merge_fn(struct request_queue *q, struct request *req, | |
| 27 | + struct bio *bio); | |
| 28 | +int attempt_back_merge(struct request_queue *q, struct request *rq); | |
| 29 | +int attempt_front_merge(struct request_queue *q, struct request *rq); | |
| 30 | +void blk_recalc_rq_segments(struct request *rq); | |
| 31 | +void blk_recalc_rq_sectors(struct request *rq, int nsect); | |
| 25 | 32 | |
| 26 | 33 | void blk_queue_congestion_threshold(struct request_queue *q); |
| 27 | 34 |