| /* |
| * Functions related to segment and merge handling |
| */ |
| #include <linux/kernel.h> |
| #include <linux/module.h> |
| #include <linux/bio.h> |
| #include <linux/blkdev.h> |
| #include <linux/scatterlist.h> |
| #include <linux/security.h> |
| |
| #include "blk.h" |
| |
| static unsigned int __blk_recalc_rq_segments(struct request_queue *q, |
| struct bio *bio) |
| { |
| struct bio_vec *bv, *bvprv = NULL; |
| int cluster, i, high, highprv = 1; |
| unsigned int seg_size, nr_phys_segs; |
| struct bio *fbio, *bbio; |
| |
| if (!bio) |
| return 0; |
| |
| fbio = bio; |
| cluster = blk_queue_cluster(q); |
| seg_size = 0; |
| nr_phys_segs = 0; |
| for_each_bio(bio) { |
| bio_for_each_segment(bv, bio, i) { |
| /* |
| * the trick here is making sure that a high page is |
| * never considered part of another segment, since that |
| * might change with the bounce page. |
| */ |
| high = page_to_pfn(bv->bv_page) > queue_bounce_pfn(q); |
| if (high || highprv) |
| goto new_segment; |
| if (cluster) { |
| if (seg_size + bv->bv_len |
| > queue_max_segment_size(q)) |
| goto new_segment; |
| if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv)) |
| goto new_segment; |
| if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv)) |
| goto new_segment; |
| |
| seg_size += bv->bv_len; |
| bvprv = bv; |
| continue; |
| } |
| new_segment: |
| if (nr_phys_segs == 1 && seg_size > |
| fbio->bi_seg_front_size) |
| fbio->bi_seg_front_size = seg_size; |
| |
| nr_phys_segs++; |
| bvprv = bv; |
| seg_size = bv->bv_len; |
| highprv = high; |
| } |
| bbio = bio; |
| } |
| |
| if (nr_phys_segs == 1 && seg_size > fbio->bi_seg_front_size) |
| fbio->bi_seg_front_size = seg_size; |
| if (seg_size > bbio->bi_seg_back_size) |
| bbio->bi_seg_back_size = seg_size; |
| |
| return nr_phys_segs; |
| } |
| |
| void blk_recalc_rq_segments(struct request *rq) |
| { |
| rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio); |
| } |
| |
| void blk_recount_segments(struct request_queue *q, struct bio *bio) |
| { |
| struct bio *nxt = bio->bi_next; |
| |
| bio->bi_next = NULL; |
| bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio); |
| bio->bi_next = nxt; |
| bio->bi_flags |= (1 << BIO_SEG_VALID); |
| } |
| EXPORT_SYMBOL(blk_recount_segments); |
| |
| static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio, |
| struct bio *nxt) |
| { |
| if (!blk_queue_cluster(q)) |
| return 0; |
| |
| if (bio->bi_seg_back_size + nxt->bi_seg_front_size > |
| queue_max_segment_size(q)) |
| return 0; |
| |
| if (!bio_has_data(bio)) |
| return 1; |
| |
| if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt))) |
| return 0; |
| |
| /* |
| * bio and nxt are contiguous in memory; check if the queue allows |
| * these two to be merged into one |
| */ |
| if (BIO_SEG_BOUNDARY(q, bio, nxt)) |
| return 1; |
| |
| return 0; |
| } |
| |
| static void |
| __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, |
| struct scatterlist *sglist, struct bio_vec **bvprv, |
| struct scatterlist **sg, int *nsegs, int *cluster) |
| { |
| |
| int nbytes = bvec->bv_len; |
| |
| if (*bvprv && *cluster) { |
| if ((*sg)->length + nbytes > queue_max_segment_size(q)) |
| goto new_segment; |
| |
| if (!BIOVEC_PHYS_MERGEABLE(*bvprv, bvec)) |
| goto new_segment; |
| if (!BIOVEC_SEG_BOUNDARY(q, *bvprv, bvec)) |
| goto new_segment; |
| |
| (*sg)->length += nbytes; |
| } else { |
| new_segment: |
| if (!*sg) |
| *sg = sglist; |
| else { |
| /* |
| * If the driver previously mapped a shorter |
| * list, we could see a termination bit |
| * prematurely unless it fully inits the sg |
| * table on each mapping. We KNOW that there |
| * must be more entries here or the driver |
| * would be buggy, so force clear the |
| * termination bit to avoid doing a full |
| * sg_init_table() in drivers for each command. |
| */ |
| sg_unmark_end(*sg); |
| *sg = sg_next(*sg); |
| } |
| |
| sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); |
| (*nsegs)++; |
| } |
| *bvprv = bvec; |
| } |
| |
| /* |
| * map a request to scatterlist, return number of sg entries setup. Caller |
| * must make sure sg can hold rq->nr_phys_segments entries |
| */ |
| int blk_rq_map_sg(struct request_queue *q, struct request *rq, |
| struct scatterlist *sglist) |
| { |
| struct bio_vec *bvec, *bvprv; |
| struct req_iterator iter; |
| struct scatterlist *sg; |
| int nsegs, cluster; |
| |
| nsegs = 0; |
| cluster = blk_queue_cluster(q); |
| |
| /* |
| * for each bio in rq |
| */ |
| bvprv = NULL; |
| sg = NULL; |
| rq_for_each_segment(bvec, rq, iter) { |
| __blk_segment_map_sg(q, bvec, sglist, &bvprv, &sg, |
| &nsegs, &cluster); |
| } /* segments in rq */ |
| |
| |
| if (unlikely(rq->cmd_flags & REQ_COPY_USER) && |
| (blk_rq_bytes(rq) & q->dma_pad_mask)) { |
| unsigned int pad_len = |
| (q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1; |
| |
| sg->length += pad_len; |
| rq->extra_len += pad_len; |
| } |
| |
| if (q->dma_drain_size && q->dma_drain_needed(rq)) { |
| if (rq->cmd_flags & REQ_WRITE) |
| memset(q->dma_drain_buffer, 0, q->dma_drain_size); |
| |
| sg->page_link &= ~0x02; |
| sg = sg_next(sg); |
| sg_set_page(sg, virt_to_page(q->dma_drain_buffer), |
| q->dma_drain_size, |
| ((unsigned long)q->dma_drain_buffer) & |
| (PAGE_SIZE - 1)); |
| nsegs++; |
| rq->extra_len += q->dma_drain_size; |
| } |
| |
| if (sg) |
| sg_mark_end(sg); |
| |
| return nsegs; |
| } |
| EXPORT_SYMBOL(blk_rq_map_sg); |
| |
| |
| /* |
| * map a request to scatterlist without combining PHY CONT |
| * blocks, return number of sg entries setup. Caller |
| * must make sure sg can hold rq->nr_phys_segments entries |
| */ |
| int blk_rq_map_sg_no_cluster(struct request_queue *q, struct request *rq, |
| struct scatterlist *sglist) |
| { |
| struct bio_vec *bvec, *bvprv; |
| struct req_iterator iter; |
| struct scatterlist *sg; |
| int nsegs, cluster = 0; |
| |
| nsegs = 0; |
| |
| /* |
| * for each bio in rq |
| */ |
| bvprv = NULL; |
| sg = NULL; |
| rq_for_each_segment(bvec, rq, iter) { |
| __blk_segment_map_sg(q, bvec, sglist, &bvprv, &sg, |
| &nsegs, &cluster); |
| } /* segments in rq */ |
| |
| |
| if (unlikely(rq->cmd_flags & REQ_COPY_USER) && |
| (blk_rq_bytes(rq) & q->dma_pad_mask)) { |
| unsigned int pad_len = |
| (q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1; |
| |
| sg->length += pad_len; |
| rq->extra_len += pad_len; |
| } |
| |
| if (q->dma_drain_size && q->dma_drain_needed(rq)) { |
| if (rq->cmd_flags & REQ_WRITE) |
| memset(q->dma_drain_buffer, 0, q->dma_drain_size); |
| |
| sg->page_link &= ~0x02; |
| sg = sg_next(sg); |
| sg_set_page(sg, virt_to_page(q->dma_drain_buffer), |
| q->dma_drain_size, |
| ((unsigned long)q->dma_drain_buffer) & |
| (PAGE_SIZE - 1)); |
| nsegs++; |
| rq->extra_len += q->dma_drain_size; |
| } |
| |
| if (sg) |
| sg_mark_end(sg); |
| |
| return nsegs; |
| } |
| EXPORT_SYMBOL(blk_rq_map_sg_no_cluster); |
| /** |
| * blk_bio_map_sg - map a bio to a scatterlist |
| * @q: request_queue in question |
| * @bio: bio being mapped |
| * @sglist: scatterlist being mapped |
| * |
| * Note: |
| * Caller must make sure sg can hold bio->bi_phys_segments entries |
| * |
| * Will return the number of sg entries setup |
| */ |
| int blk_bio_map_sg(struct request_queue *q, struct bio *bio, |
| struct scatterlist *sglist) |
| { |
| struct bio_vec *bvec, *bvprv; |
| struct scatterlist *sg; |
| int nsegs, cluster; |
| unsigned long i; |
| |
| nsegs = 0; |
| cluster = blk_queue_cluster(q); |
| |
| bvprv = NULL; |
| sg = NULL; |
| bio_for_each_segment(bvec, bio, i) { |
| __blk_segment_map_sg(q, bvec, sglist, &bvprv, &sg, |
| &nsegs, &cluster); |
| } /* segments in bio */ |
| |
| if (sg) |
| sg_mark_end(sg); |
| |
| BUG_ON(bio->bi_phys_segments && nsegs > bio->bi_phys_segments); |
| return nsegs; |
| } |
| EXPORT_SYMBOL(blk_bio_map_sg); |
| |
| static inline int ll_new_hw_segment(struct request_queue *q, |
| struct request *req, |
| struct bio *bio) |
| { |
| int nr_phys_segs = bio_phys_segments(q, bio); |
| |
| if (req->nr_phys_segments + nr_phys_segs > queue_max_segments(q)) |
| goto no_merge; |
| |
| if (bio_integrity(bio) && blk_integrity_merge_bio(q, req, bio)) |
| goto no_merge; |
| |
| /* |
| * This will form the start of a new hw segment. Bump both |
| * counters. |
| */ |
| req->nr_phys_segments += nr_phys_segs; |
| return 1; |
| |
| no_merge: |
| req->cmd_flags |= REQ_NOMERGE; |
| if (req == q->last_merge) |
| q->last_merge = NULL; |
| return 0; |
| } |
| |
| int ll_back_merge_fn(struct request_queue *q, struct request *req, |
| struct bio *bio) |
| { |
| if (blk_rq_sectors(req) + bio_sectors(bio) > |
| blk_rq_get_max_sectors(req)) { |
| req->cmd_flags |= REQ_NOMERGE; |
| if (req == q->last_merge) |
| q->last_merge = NULL; |
| return 0; |
| } |
| if (!bio_flagged(req->biotail, BIO_SEG_VALID)) |
| blk_recount_segments(q, req->biotail); |
| if (!bio_flagged(bio, BIO_SEG_VALID)) |
| blk_recount_segments(q, bio); |
| |
| return ll_new_hw_segment(q, req, bio); |
| } |
| |
| int ll_front_merge_fn(struct request_queue *q, struct request *req, |
| struct bio *bio) |
| { |
| if (blk_rq_sectors(req) + bio_sectors(bio) > |
| blk_rq_get_max_sectors(req)) { |
| req->cmd_flags |= REQ_NOMERGE; |
| if (req == q->last_merge) |
| q->last_merge = NULL; |
| return 0; |
| } |
| if (!bio_flagged(bio, BIO_SEG_VALID)) |
| blk_recount_segments(q, bio); |
| if (!bio_flagged(req->bio, BIO_SEG_VALID)) |
| blk_recount_segments(q, req->bio); |
| |
| return ll_new_hw_segment(q, req, bio); |
| } |
| |
| static int ll_merge_requests_fn(struct request_queue *q, struct request *req, |
| struct request *next) |
| { |
| int total_phys_segments; |
| unsigned int seg_size = |
| req->biotail->bi_seg_back_size + next->bio->bi_seg_front_size; |
| |
| /* |
| * First check if the either of the requests are re-queued |
| * requests. Can't merge them if they are. |
| */ |
| if (req->special || next->special) |
| return 0; |
| |
| /* |
| * Will it become too large? |
| */ |
| if ((blk_rq_sectors(req) + blk_rq_sectors(next)) > |
| blk_rq_get_max_sectors(req)) |
| return 0; |
| |
| total_phys_segments = req->nr_phys_segments + next->nr_phys_segments; |
| if (blk_phys_contig_segment(q, req->biotail, next->bio)) { |
| if (req->nr_phys_segments == 1) |
| req->bio->bi_seg_front_size = seg_size; |
| if (next->nr_phys_segments == 1) |
| next->biotail->bi_seg_back_size = seg_size; |
| total_phys_segments--; |
| } |
| |
| if (total_phys_segments > queue_max_segments(q)) |
| return 0; |
| |
| if (blk_integrity_rq(req) && blk_integrity_merge_rq(q, req, next)) |
| return 0; |
| |
| /* Merge is OK... */ |
| req->nr_phys_segments = total_phys_segments; |
| return 1; |
| } |
| |
| /** |
| * blk_rq_set_mixed_merge - mark a request as mixed merge |
| * @rq: request to mark as mixed merge |
| * |
| * Description: |
| * @rq is about to be mixed merged. Make sure the attributes |
| * which can be mixed are set in each bio and mark @rq as mixed |
| * merged. |
| */ |
| void blk_rq_set_mixed_merge(struct request *rq) |
| { |
| unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK; |
| struct bio *bio; |
| |
| if (rq->cmd_flags & REQ_MIXED_MERGE) |
| return; |
| |
| /* |
| * @rq will no longer represent mixable attributes for all the |
| * contained bios. It will just track those of the first one. |
| * Distributes the attributs to each bio. |
| */ |
| for (bio = rq->bio; bio; bio = bio->bi_next) { |
| WARN_ON_ONCE((bio->bi_rw & REQ_FAILFAST_MASK) && |
| (bio->bi_rw & REQ_FAILFAST_MASK) != ff); |
| bio->bi_rw |= ff; |
| } |
| rq->cmd_flags |= REQ_MIXED_MERGE; |
| } |
| |
| static void blk_account_io_merge(struct request *req) |
| { |
| if (blk_do_io_stat(req)) { |
| struct hd_struct *part; |
| int cpu; |
| |
| cpu = part_stat_lock(); |
| part = req->part; |
| |
| part_round_stats(cpu, part); |
| part_dec_in_flight(part, rq_data_dir(req)); |
| |
| hd_struct_put(part); |
| part_stat_unlock(); |
| } |
| } |
| |
| /* |
| * Has to be called with the request spinlock acquired |
| */ |
| static int attempt_merge(struct request_queue *q, struct request *req, |
| struct request *next) |
| { |
| if (!rq_mergeable(req) || !rq_mergeable(next)) |
| return 0; |
| |
| if (!blk_check_merge_flags(req->cmd_flags, next->cmd_flags)) |
| return 0; |
| |
| /* |
| * not contiguous |
| */ |
| if (blk_rq_pos(req) + blk_rq_sectors(req) != blk_rq_pos(next)) |
| return 0; |
| |
| if (rq_data_dir(req) != rq_data_dir(next) |
| || req->rq_disk != next->rq_disk |
| || next->special) |
| return 0; |
| |
| if (req->cmd_flags & REQ_WRITE_SAME && |
| !blk_write_same_mergeable(req->bio, next->bio)) |
| return 0; |
| |
| /* |
| * If we are allowed to merge, then append bio list |
| * from next to rq and release next. merge_requests_fn |
| * will have updated segment counts, update sector |
| * counts here. |
| */ |
| if (!ll_merge_requests_fn(q, req, next)) |
| return 0; |
| |
| /* |
| * If failfast settings disagree or any of the two is already |
| * a mixed merge, mark both as mixed before proceeding. This |
| * makes sure that all involved bios have mixable attributes |
| * set properly. |
| */ |
| if ((req->cmd_flags | next->cmd_flags) & REQ_MIXED_MERGE || |
| (req->cmd_flags & REQ_FAILFAST_MASK) != |
| (next->cmd_flags & REQ_FAILFAST_MASK)) { |
| blk_rq_set_mixed_merge(req); |
| blk_rq_set_mixed_merge(next); |
| } |
| |
| /* |
| * At this point we have either done a back merge |
| * or front merge. We need the smaller start_time of |
| * the merged requests to be the current request |
| * for accounting purposes. |
| */ |
| if (time_after(req->start_time, next->start_time)) |
| req->start_time = next->start_time; |
| |
| req->biotail->bi_next = next->bio; |
| req->biotail = next->biotail; |
| |
| req->__data_len += blk_rq_bytes(next); |
| |
| elv_merge_requests(q, req, next); |
| |
| /* |
| * 'next' is going away, so update stats accordingly |
| */ |
| blk_account_io_merge(next); |
| |
| req->ioprio = ioprio_best(req->ioprio, next->ioprio); |
| if (blk_rq_cpu_valid(next)) |
| req->cpu = next->cpu; |
| |
| /* owner-ship of bio passed from next to req */ |
| next->bio = NULL; |
| __blk_put_request(q, next); |
| return 1; |
| } |
| |
| int attempt_back_merge(struct request_queue *q, struct request *rq) |
| { |
| struct request *next = elv_latter_request(q, rq); |
| |
| if (next) |
| return attempt_merge(q, rq, next); |
| |
| return 0; |
| } |
| |
| int attempt_front_merge(struct request_queue *q, struct request *rq) |
| { |
| struct request *prev = elv_former_request(q, rq); |
| |
| if (prev) |
| return attempt_merge(q, prev, rq); |
| |
| return 0; |
| } |
| |
| int blk_attempt_req_merge(struct request_queue *q, struct request *rq, |
| struct request *next) |
| { |
| return attempt_merge(q, rq, next); |
| } |
| |
| bool blk_rq_merge_ok(struct request *rq, struct bio *bio) |
| { |
| if (!rq_mergeable(rq) || !bio_mergeable(bio)) |
| return false; |
| |
| if (!blk_check_merge_flags(rq->cmd_flags, bio->bi_rw)) |
| return false; |
| |
| /* different data direction or already started, don't merge */ |
| if (bio_data_dir(bio) != rq_data_dir(rq)) |
| return false; |
| |
| /* must be same device and not a special request */ |
| if (rq->rq_disk != bio->bi_bdev->bd_disk || rq->special) |
| return false; |
| |
| /* only merge integrity protected bio into ditto rq */ |
| if (bio_integrity(bio) != blk_integrity_rq(rq)) |
| return false; |
| |
| /* must be using the same buffer */ |
| if (rq->cmd_flags & REQ_WRITE_SAME && |
| !blk_write_same_mergeable(rq->bio, bio)) |
| return false; |
| |
| /* Don't merge bios of files with different encryption */ |
| if (!security_allow_merge_bio(rq->bio, bio)) |
| return false; |
| |
| return true; |
| } |
| |
| int blk_try_merge(struct request *rq, struct bio *bio) |
| { |
| if (blk_rq_pos(rq) + blk_rq_sectors(rq) == bio->bi_sector) |
| return ELEVATOR_BACK_MERGE; |
| else if (blk_rq_pos(rq) - bio_sectors(bio) == bio->bi_sector) |
| return ELEVATOR_FRONT_MERGE; |
| return ELEVATOR_NO_MERGE; |
| } |