1d6d48196SJens Axboe /* 2d6d48196SJens Axboe * Functions related to segment and merge handling 3d6d48196SJens Axboe */ 4d6d48196SJens Axboe #include <linux/kernel.h> 5d6d48196SJens Axboe #include <linux/module.h> 6d6d48196SJens Axboe #include <linux/bio.h> 7d6d48196SJens Axboe #include <linux/blkdev.h> 8d6d48196SJens Axboe #include <linux/scatterlist.h> 9d6d48196SJens Axboe 10d6d48196SJens Axboe #include "blk.h" 11d6d48196SJens Axboe 12d6d48196SJens Axboe void blk_recalc_rq_sectors(struct request *rq, int nsect) 13d6d48196SJens Axboe { 14e17fc0a1SDavid Woodhouse if (blk_fs_request(rq) || blk_discard_rq(rq)) { 15d6d48196SJens Axboe rq->hard_sector += nsect; 16d6d48196SJens Axboe rq->hard_nr_sectors -= nsect; 17d6d48196SJens Axboe 18d6d48196SJens Axboe /* 19d6d48196SJens Axboe * Move the I/O submission pointers ahead if required. 20d6d48196SJens Axboe */ 21d6d48196SJens Axboe if ((rq->nr_sectors >= rq->hard_nr_sectors) && 22d6d48196SJens Axboe (rq->sector <= rq->hard_sector)) { 23d6d48196SJens Axboe rq->sector = rq->hard_sector; 24d6d48196SJens Axboe rq->nr_sectors = rq->hard_nr_sectors; 25d6d48196SJens Axboe rq->hard_cur_sectors = bio_cur_sectors(rq->bio); 26d6d48196SJens Axboe rq->current_nr_sectors = rq->hard_cur_sectors; 27d6d48196SJens Axboe rq->buffer = bio_data(rq->bio); 28d6d48196SJens Axboe } 29d6d48196SJens Axboe 30d6d48196SJens Axboe /* 31d6d48196SJens Axboe * if total number of sectors is less than the first segment 32d6d48196SJens Axboe * size, something has gone terribly wrong 33d6d48196SJens Axboe */ 34d6d48196SJens Axboe if (rq->nr_sectors < rq->current_nr_sectors) { 356728cb0eSJens Axboe printk(KERN_ERR "blk: request botched\n"); 36d6d48196SJens Axboe rq->nr_sectors = rq->current_nr_sectors; 37d6d48196SJens Axboe } 38d6d48196SJens Axboe } 39d6d48196SJens Axboe } 40d6d48196SJens Axboe 411e428079SJens Axboe static unsigned int __blk_recalc_rq_segments(struct request_queue *q, 421e428079SJens Axboe struct bio *bio, 431e428079SJens Axboe unsigned int *seg_size_ptr) 44d6d48196SJens Axboe { 45d6d48196SJens Axboe unsigned int phys_size; 46d6d48196SJens Axboe struct bio_vec *bv, *bvprv = NULL; 471e428079SJens Axboe int cluster, i, high, highprv = 1; 481e428079SJens Axboe unsigned int seg_size, nr_phys_segs; 491e428079SJens Axboe struct bio *fbio; 50d6d48196SJens Axboe 511e428079SJens Axboe if (!bio) 521e428079SJens Axboe return 0; 53d6d48196SJens Axboe 541e428079SJens Axboe fbio = bio; 5575ad23bcSNick Piggin cluster = test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags); 565df97b91SMikulas Patocka seg_size = 0; 575df97b91SMikulas Patocka phys_size = nr_phys_segs = 0; 581e428079SJens Axboe for_each_bio(bio) { 591e428079SJens Axboe bio_for_each_segment(bv, bio, i) { 60d6d48196SJens Axboe /* 611e428079SJens Axboe * the trick here is making sure that a high page is 621e428079SJens Axboe * never considered part of another segment, since that 631e428079SJens Axboe * might change with the bounce page. 64d6d48196SJens Axboe */ 65d6d48196SJens Axboe high = page_to_pfn(bv->bv_page) > q->bounce_pfn; 66d6d48196SJens Axboe if (high || highprv) 67b8b3e16cSMikulas Patocka goto new_segment; 68d6d48196SJens Axboe if (cluster) { 69d6d48196SJens Axboe if (seg_size + bv->bv_len > q->max_segment_size) 70d6d48196SJens Axboe goto new_segment; 71d6d48196SJens Axboe if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv)) 72d6d48196SJens Axboe goto new_segment; 73d6d48196SJens Axboe if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv)) 74d6d48196SJens Axboe goto new_segment; 75d6d48196SJens Axboe 76d6d48196SJens Axboe seg_size += bv->bv_len; 77d6d48196SJens Axboe bvprv = bv; 78d6d48196SJens Axboe continue; 79d6d48196SJens Axboe } 80d6d48196SJens Axboe new_segment: 811e428079SJens Axboe if (nr_phys_segs == 1 && seg_size > 821e428079SJens Axboe fbio->bi_seg_front_size) 831e428079SJens Axboe fbio->bi_seg_front_size = seg_size; 8486771427SFUJITA Tomonori 85d6d48196SJens Axboe nr_phys_segs++; 86d6d48196SJens Axboe bvprv = bv; 87d6d48196SJens Axboe seg_size = bv->bv_len; 88d6d48196SJens Axboe highprv = high; 89d6d48196SJens Axboe } 901e428079SJens Axboe } 91d6d48196SJens Axboe 921e428079SJens Axboe if (seg_size_ptr) 931e428079SJens Axboe *seg_size_ptr = seg_size; 941e428079SJens Axboe 951e428079SJens Axboe return nr_phys_segs; 961e428079SJens Axboe } 971e428079SJens Axboe 981e428079SJens Axboe void blk_recalc_rq_segments(struct request *rq) 991e428079SJens Axboe { 1001e428079SJens Axboe unsigned int seg_size = 0, phys_segs; 1011e428079SJens Axboe 1021e428079SJens Axboe phys_segs = __blk_recalc_rq_segments(rq->q, rq->bio, &seg_size); 1031e428079SJens Axboe 1041e428079SJens Axboe if (phys_segs == 1 && seg_size > rq->bio->bi_seg_front_size) 10586771427SFUJITA Tomonori rq->bio->bi_seg_front_size = seg_size; 10686771427SFUJITA Tomonori if (seg_size > rq->biotail->bi_seg_back_size) 10786771427SFUJITA Tomonori rq->biotail->bi_seg_back_size = seg_size; 10886771427SFUJITA Tomonori 1091e428079SJens Axboe rq->nr_phys_segments = phys_segs; 110d6d48196SJens Axboe } 111d6d48196SJens Axboe 112d6d48196SJens Axboe void blk_recount_segments(struct request_queue *q, struct bio *bio) 113d6d48196SJens Axboe { 114d6d48196SJens Axboe struct bio *nxt = bio->bi_next; 1151e428079SJens Axboe 116d6d48196SJens Axboe bio->bi_next = NULL; 1171e428079SJens Axboe bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, NULL); 118d6d48196SJens Axboe bio->bi_next = nxt; 119d6d48196SJens Axboe bio->bi_flags |= (1 << BIO_SEG_VALID); 120d6d48196SJens Axboe } 121d6d48196SJens Axboe EXPORT_SYMBOL(blk_recount_segments); 122d6d48196SJens Axboe 123d6d48196SJens Axboe static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio, 124d6d48196SJens Axboe struct bio *nxt) 125d6d48196SJens Axboe { 12675ad23bcSNick Piggin if (!test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags)) 127d6d48196SJens Axboe return 0; 128d6d48196SJens Axboe 12986771427SFUJITA Tomonori if (bio->bi_seg_back_size + nxt->bi_seg_front_size > 13086771427SFUJITA Tomonori q->max_segment_size) 131d6d48196SJens Axboe return 0; 132d6d48196SJens Axboe 133e17fc0a1SDavid Woodhouse if (!bio_has_data(bio)) 134e17fc0a1SDavid Woodhouse return 1; 135e17fc0a1SDavid Woodhouse 136e17fc0a1SDavid Woodhouse if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt))) 137e17fc0a1SDavid Woodhouse return 0; 138e17fc0a1SDavid Woodhouse 139d6d48196SJens Axboe /* 140e17fc0a1SDavid Woodhouse * bio and nxt are contiguous in memory; check if the queue allows 141d6d48196SJens Axboe * these two to be merged into one 142d6d48196SJens Axboe */ 143d6d48196SJens Axboe if (BIO_SEG_BOUNDARY(q, bio, nxt)) 144d6d48196SJens Axboe return 1; 145d6d48196SJens Axboe 146d6d48196SJens Axboe return 0; 147d6d48196SJens Axboe } 148d6d48196SJens Axboe 149d6d48196SJens Axboe /* 150d6d48196SJens Axboe * map a request to scatterlist, return number of sg entries setup. Caller 151d6d48196SJens Axboe * must make sure sg can hold rq->nr_phys_segments entries 152d6d48196SJens Axboe */ 153d6d48196SJens Axboe int blk_rq_map_sg(struct request_queue *q, struct request *rq, 154d6d48196SJens Axboe struct scatterlist *sglist) 155d6d48196SJens Axboe { 156d6d48196SJens Axboe struct bio_vec *bvec, *bvprv; 157d6d48196SJens Axboe struct req_iterator iter; 158d6d48196SJens Axboe struct scatterlist *sg; 159d6d48196SJens Axboe int nsegs, cluster; 160d6d48196SJens Axboe 161d6d48196SJens Axboe nsegs = 0; 16275ad23bcSNick Piggin cluster = test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags); 163d6d48196SJens Axboe 164d6d48196SJens Axboe /* 165d6d48196SJens Axboe * for each bio in rq 166d6d48196SJens Axboe */ 167d6d48196SJens Axboe bvprv = NULL; 168d6d48196SJens Axboe sg = NULL; 169d6d48196SJens Axboe rq_for_each_segment(bvec, rq, iter) { 170d6d48196SJens Axboe int nbytes = bvec->bv_len; 171d6d48196SJens Axboe 172d6d48196SJens Axboe if (bvprv && cluster) { 173d6d48196SJens Axboe if (sg->length + nbytes > q->max_segment_size) 174d6d48196SJens Axboe goto new_segment; 175d6d48196SJens Axboe 176d6d48196SJens Axboe if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) 177d6d48196SJens Axboe goto new_segment; 178d6d48196SJens Axboe if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec)) 179d6d48196SJens Axboe goto new_segment; 180d6d48196SJens Axboe 181d6d48196SJens Axboe sg->length += nbytes; 182d6d48196SJens Axboe } else { 183d6d48196SJens Axboe new_segment: 184d6d48196SJens Axboe if (!sg) 185d6d48196SJens Axboe sg = sglist; 186d6d48196SJens Axboe else { 187d6d48196SJens Axboe /* 188d6d48196SJens Axboe * If the driver previously mapped a shorter 189d6d48196SJens Axboe * list, we could see a termination bit 190d6d48196SJens Axboe * prematurely unless it fully inits the sg 191d6d48196SJens Axboe * table on each mapping. We KNOW that there 192d6d48196SJens Axboe * must be more entries here or the driver 193d6d48196SJens Axboe * would be buggy, so force clear the 194d6d48196SJens Axboe * termination bit to avoid doing a full 195d6d48196SJens Axboe * sg_init_table() in drivers for each command. 196d6d48196SJens Axboe */ 197d6d48196SJens Axboe sg->page_link &= ~0x02; 198d6d48196SJens Axboe sg = sg_next(sg); 199d6d48196SJens Axboe } 200d6d48196SJens Axboe 201d6d48196SJens Axboe sg_set_page(sg, bvec->bv_page, nbytes, bvec->bv_offset); 202d6d48196SJens Axboe nsegs++; 203d6d48196SJens Axboe } 204d6d48196SJens Axboe bvprv = bvec; 205d6d48196SJens Axboe } /* segments in rq */ 206d6d48196SJens Axboe 207f18573abSFUJITA Tomonori 208f18573abSFUJITA Tomonori if (unlikely(rq->cmd_flags & REQ_COPY_USER) && 209f18573abSFUJITA Tomonori (rq->data_len & q->dma_pad_mask)) { 210f18573abSFUJITA Tomonori unsigned int pad_len = (q->dma_pad_mask & ~rq->data_len) + 1; 211f18573abSFUJITA Tomonori 212f18573abSFUJITA Tomonori sg->length += pad_len; 213f18573abSFUJITA Tomonori rq->extra_len += pad_len; 214f18573abSFUJITA Tomonori } 215f18573abSFUJITA Tomonori 2162fb98e84STejun Heo if (q->dma_drain_size && q->dma_drain_needed(rq)) { 217db0a2e00STejun Heo if (rq->cmd_flags & REQ_RW) 218db0a2e00STejun Heo memset(q->dma_drain_buffer, 0, q->dma_drain_size); 219db0a2e00STejun Heo 220d6d48196SJens Axboe sg->page_link &= ~0x02; 221d6d48196SJens Axboe sg = sg_next(sg); 222d6d48196SJens Axboe sg_set_page(sg, virt_to_page(q->dma_drain_buffer), 223d6d48196SJens Axboe q->dma_drain_size, 224d6d48196SJens Axboe ((unsigned long)q->dma_drain_buffer) & 225d6d48196SJens Axboe (PAGE_SIZE - 1)); 226d6d48196SJens Axboe nsegs++; 2277a85f889SFUJITA Tomonori rq->extra_len += q->dma_drain_size; 228d6d48196SJens Axboe } 229d6d48196SJens Axboe 230d6d48196SJens Axboe if (sg) 231d6d48196SJens Axboe sg_mark_end(sg); 232d6d48196SJens Axboe 233d6d48196SJens Axboe return nsegs; 234d6d48196SJens Axboe } 235d6d48196SJens Axboe EXPORT_SYMBOL(blk_rq_map_sg); 236d6d48196SJens Axboe 237d6d48196SJens Axboe static inline int ll_new_hw_segment(struct request_queue *q, 238d6d48196SJens Axboe struct request *req, 239d6d48196SJens Axboe struct bio *bio) 240d6d48196SJens Axboe { 241d6d48196SJens Axboe int nr_phys_segs = bio_phys_segments(q, bio); 242d6d48196SJens Axboe 2435df97b91SMikulas Patocka if (req->nr_phys_segments + nr_phys_segs > q->max_hw_segments 244d6d48196SJens Axboe || req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) { 245d6d48196SJens Axboe req->cmd_flags |= REQ_NOMERGE; 246d6d48196SJens Axboe if (req == q->last_merge) 247d6d48196SJens Axboe q->last_merge = NULL; 248d6d48196SJens Axboe return 0; 249d6d48196SJens Axboe } 250d6d48196SJens Axboe 251d6d48196SJens Axboe /* 252d6d48196SJens Axboe * This will form the start of a new hw segment. Bump both 253d6d48196SJens Axboe * counters. 254d6d48196SJens Axboe */ 255d6d48196SJens Axboe req->nr_phys_segments += nr_phys_segs; 256d6d48196SJens Axboe return 1; 257d6d48196SJens Axboe } 258d6d48196SJens Axboe 259d6d48196SJens Axboe int ll_back_merge_fn(struct request_queue *q, struct request *req, 260d6d48196SJens Axboe struct bio *bio) 261d6d48196SJens Axboe { 262d6d48196SJens Axboe unsigned short max_sectors; 263d6d48196SJens Axboe 264d6d48196SJens Axboe if (unlikely(blk_pc_request(req))) 265d6d48196SJens Axboe max_sectors = q->max_hw_sectors; 266d6d48196SJens Axboe else 267d6d48196SJens Axboe max_sectors = q->max_sectors; 268d6d48196SJens Axboe 269d6d48196SJens Axboe if (req->nr_sectors + bio_sectors(bio) > max_sectors) { 270d6d48196SJens Axboe req->cmd_flags |= REQ_NOMERGE; 271d6d48196SJens Axboe if (req == q->last_merge) 272d6d48196SJens Axboe q->last_merge = NULL; 273d6d48196SJens Axboe return 0; 274d6d48196SJens Axboe } 2752cdf79caSJens Axboe if (!bio_flagged(req->biotail, BIO_SEG_VALID)) 276d6d48196SJens Axboe blk_recount_segments(q, req->biotail); 2772cdf79caSJens Axboe if (!bio_flagged(bio, BIO_SEG_VALID)) 278d6d48196SJens Axboe blk_recount_segments(q, bio); 279d6d48196SJens Axboe 280d6d48196SJens Axboe return ll_new_hw_segment(q, req, bio); 281d6d48196SJens Axboe } 282d6d48196SJens Axboe 283d6d48196SJens Axboe int ll_front_merge_fn(struct request_queue *q, struct request *req, 284d6d48196SJens Axboe struct bio *bio) 285d6d48196SJens Axboe { 286d6d48196SJens Axboe unsigned short max_sectors; 287d6d48196SJens Axboe 288d6d48196SJens Axboe if (unlikely(blk_pc_request(req))) 289d6d48196SJens Axboe max_sectors = q->max_hw_sectors; 290d6d48196SJens Axboe else 291d6d48196SJens Axboe max_sectors = q->max_sectors; 292d6d48196SJens Axboe 293d6d48196SJens Axboe 294d6d48196SJens Axboe if (req->nr_sectors + bio_sectors(bio) > max_sectors) { 295d6d48196SJens Axboe req->cmd_flags |= REQ_NOMERGE; 296d6d48196SJens Axboe if (req == q->last_merge) 297d6d48196SJens Axboe q->last_merge = NULL; 298d6d48196SJens Axboe return 0; 299d6d48196SJens Axboe } 3002cdf79caSJens Axboe if (!bio_flagged(bio, BIO_SEG_VALID)) 301d6d48196SJens Axboe blk_recount_segments(q, bio); 3022cdf79caSJens Axboe if (!bio_flagged(req->bio, BIO_SEG_VALID)) 303d6d48196SJens Axboe blk_recount_segments(q, req->bio); 304d6d48196SJens Axboe 305d6d48196SJens Axboe return ll_new_hw_segment(q, req, bio); 306d6d48196SJens Axboe } 307d6d48196SJens Axboe 308d6d48196SJens Axboe static int ll_merge_requests_fn(struct request_queue *q, struct request *req, 309d6d48196SJens Axboe struct request *next) 310d6d48196SJens Axboe { 311d6d48196SJens Axboe int total_phys_segments; 31286771427SFUJITA Tomonori unsigned int seg_size = 31386771427SFUJITA Tomonori req->biotail->bi_seg_back_size + next->bio->bi_seg_front_size; 314d6d48196SJens Axboe 315d6d48196SJens Axboe /* 316d6d48196SJens Axboe * First check if the either of the requests are re-queued 317d6d48196SJens Axboe * requests. Can't merge them if they are. 318d6d48196SJens Axboe */ 319d6d48196SJens Axboe if (req->special || next->special) 320d6d48196SJens Axboe return 0; 321d6d48196SJens Axboe 322d6d48196SJens Axboe /* 323d6d48196SJens Axboe * Will it become too large? 324d6d48196SJens Axboe */ 325d6d48196SJens Axboe if ((req->nr_sectors + next->nr_sectors) > q->max_sectors) 326d6d48196SJens Axboe return 0; 327d6d48196SJens Axboe 328d6d48196SJens Axboe total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; 32986771427SFUJITA Tomonori if (blk_phys_contig_segment(q, req->biotail, next->bio)) { 33086771427SFUJITA Tomonori if (req->nr_phys_segments == 1) 33186771427SFUJITA Tomonori req->bio->bi_seg_front_size = seg_size; 33286771427SFUJITA Tomonori if (next->nr_phys_segments == 1) 33386771427SFUJITA Tomonori next->biotail->bi_seg_back_size = seg_size; 334d6d48196SJens Axboe total_phys_segments--; 33586771427SFUJITA Tomonori } 336d6d48196SJens Axboe 337d6d48196SJens Axboe if (total_phys_segments > q->max_phys_segments) 338d6d48196SJens Axboe return 0; 339d6d48196SJens Axboe 3405df97b91SMikulas Patocka if (total_phys_segments > q->max_hw_segments) 341d6d48196SJens Axboe return 0; 342d6d48196SJens Axboe 343d6d48196SJens Axboe /* Merge is OK... */ 344d6d48196SJens Axboe req->nr_phys_segments = total_phys_segments; 345d6d48196SJens Axboe return 1; 346d6d48196SJens Axboe } 347d6d48196SJens Axboe 348d6d48196SJens Axboe /* 349d6d48196SJens Axboe * Has to be called with the request spinlock acquired 350d6d48196SJens Axboe */ 351d6d48196SJens Axboe static int attempt_merge(struct request_queue *q, struct request *req, 352d6d48196SJens Axboe struct request *next) 353d6d48196SJens Axboe { 354d6d48196SJens Axboe if (!rq_mergeable(req) || !rq_mergeable(next)) 355d6d48196SJens Axboe return 0; 356d6d48196SJens Axboe 357d6d48196SJens Axboe /* 358d6d48196SJens Axboe * not contiguous 359d6d48196SJens Axboe */ 360d6d48196SJens Axboe if (req->sector + req->nr_sectors != next->sector) 361d6d48196SJens Axboe return 0; 362d6d48196SJens Axboe 363d6d48196SJens Axboe if (rq_data_dir(req) != rq_data_dir(next) 364d6d48196SJens Axboe || req->rq_disk != next->rq_disk 365d6d48196SJens Axboe || next->special) 366d6d48196SJens Axboe return 0; 367d6d48196SJens Axboe 3687ba1ba12SMartin K. Petersen if (blk_integrity_rq(req) != blk_integrity_rq(next)) 3697ba1ba12SMartin K. Petersen return 0; 3707ba1ba12SMartin K. Petersen 371d6d48196SJens Axboe /* 372d6d48196SJens Axboe * If we are allowed to merge, then append bio list 373d6d48196SJens Axboe * from next to rq and release next. merge_requests_fn 374d6d48196SJens Axboe * will have updated segment counts, update sector 375d6d48196SJens Axboe * counts here. 376d6d48196SJens Axboe */ 377d6d48196SJens Axboe if (!ll_merge_requests_fn(q, req, next)) 378d6d48196SJens Axboe return 0; 379d6d48196SJens Axboe 380d6d48196SJens Axboe /* 381d6d48196SJens Axboe * At this point we have either done a back merge 382d6d48196SJens Axboe * or front merge. We need the smaller start_time of 383d6d48196SJens Axboe * the merged requests to be the current request 384d6d48196SJens Axboe * for accounting purposes. 385d6d48196SJens Axboe */ 386d6d48196SJens Axboe if (time_after(req->start_time, next->start_time)) 387d6d48196SJens Axboe req->start_time = next->start_time; 388d6d48196SJens Axboe 389d6d48196SJens Axboe req->biotail->bi_next = next->bio; 390d6d48196SJens Axboe req->biotail = next->biotail; 391d6d48196SJens Axboe 392d6d48196SJens Axboe req->nr_sectors = req->hard_nr_sectors += next->hard_nr_sectors; 393d6d48196SJens Axboe 394d6d48196SJens Axboe elv_merge_requests(q, req, next); 395d6d48196SJens Axboe 396d6d48196SJens Axboe if (req->rq_disk) { 397e71bf0d0STejun Heo struct hd_struct *part; 398c9959059STejun Heo int cpu; 399e71bf0d0STejun Heo 400074a7acaSTejun Heo cpu = part_stat_lock(); 401e71bf0d0STejun Heo part = disk_map_sector_rcu(req->rq_disk, req->sector); 402c9959059STejun Heo 403c9959059STejun Heo part_round_stats(cpu, part); 404074a7acaSTejun Heo part_dec_in_flight(part); 405e71bf0d0STejun Heo 406074a7acaSTejun Heo part_stat_unlock(); 407d6d48196SJens Axboe } 408d6d48196SJens Axboe 409d6d48196SJens Axboe req->ioprio = ioprio_best(req->ioprio, next->ioprio); 410ab780f1eSJens Axboe if (blk_rq_cpu_valid(next)) 411ab780f1eSJens Axboe req->cpu = next->cpu; 412d6d48196SJens Axboe 413d6d48196SJens Axboe __blk_put_request(q, next); 414d6d48196SJens Axboe return 1; 415d6d48196SJens Axboe } 416d6d48196SJens Axboe 417d6d48196SJens Axboe int attempt_back_merge(struct request_queue *q, struct request *rq) 418d6d48196SJens Axboe { 419d6d48196SJens Axboe struct request *next = elv_latter_request(q, rq); 420d6d48196SJens Axboe 421d6d48196SJens Axboe if (next) 422d6d48196SJens Axboe return attempt_merge(q, rq, next); 423d6d48196SJens Axboe 424d6d48196SJens Axboe return 0; 425d6d48196SJens Axboe } 426d6d48196SJens Axboe 427d6d48196SJens Axboe int attempt_front_merge(struct request_queue *q, struct request *rq) 428d6d48196SJens Axboe { 429d6d48196SJens Axboe struct request *prev = elv_former_request(q, rq); 430d6d48196SJens Axboe 431d6d48196SJens Axboe if (prev) 432d6d48196SJens Axboe return attempt_merge(q, prev, rq); 433d6d48196SJens Axboe 434d6d48196SJens Axboe return 0; 435d6d48196SJens Axboe } 436