block: ll_rw_blk.c split, add blk-merge.c
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Jens Axboe
parent
db1d08c646
commit
d6d4819696
@ -4,7 +4,7 @@
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obj-$(CONFIG_BLOCK) := elevator.o blk-core.o blk-tag.o blk-sysfs.o \
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blk-barrier.o blk-settings.o blk-ioc.o blk-map.o \
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blk-exec.o ioctl.o genhd.o scsi_ioctl.o
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blk-exec.o blk-merge.o ioctl.o genhd.o scsi_ioctl.o
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obj-$(CONFIG_BLK_DEV_BSG) += bsg.o
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obj-$(CONFIG_IOSCHED_NOOP) += noop-iosched.o
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478
block/blk-core.c
478
block/blk-core.c
@ -29,7 +29,6 @@
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#include <linux/cpu.h>
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#include <linux/blktrace_api.h>
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#include <linux/fault-inject.h>
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#include <linux/scatterlist.h>
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#include "blk.h"
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@ -181,376 +180,6 @@ void blk_dump_rq_flags(struct request *rq, char *msg)
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EXPORT_SYMBOL(blk_dump_rq_flags);
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static void blk_recalc_rq_segments(struct request *rq)
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{
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int nr_phys_segs;
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int nr_hw_segs;
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unsigned int phys_size;
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unsigned int hw_size;
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struct bio_vec *bv, *bvprv = NULL;
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int seg_size;
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int hw_seg_size;
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int cluster;
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struct req_iterator iter;
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int high, highprv = 1;
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struct request_queue *q = rq->q;
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if (!rq->bio)
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return;
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cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
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hw_seg_size = seg_size = 0;
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phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0;
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rq_for_each_segment(bv, rq, iter) {
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/*
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* the trick here is making sure that a high page is never
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* considered part of another segment, since that might
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* change with the bounce page.
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*/
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high = page_to_pfn(bv->bv_page) > q->bounce_pfn;
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if (high || highprv)
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goto new_hw_segment;
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if (cluster) {
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if (seg_size + bv->bv_len > q->max_segment_size)
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goto new_segment;
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if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv))
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goto new_segment;
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if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv))
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goto new_segment;
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if (BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len))
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goto new_hw_segment;
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seg_size += bv->bv_len;
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hw_seg_size += bv->bv_len;
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bvprv = bv;
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continue;
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}
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new_segment:
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if (BIOVEC_VIRT_MERGEABLE(bvprv, bv) &&
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!BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len))
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hw_seg_size += bv->bv_len;
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else {
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new_hw_segment:
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if (nr_hw_segs == 1 &&
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hw_seg_size > rq->bio->bi_hw_front_size)
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rq->bio->bi_hw_front_size = hw_seg_size;
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hw_seg_size = BIOVEC_VIRT_START_SIZE(bv) + bv->bv_len;
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nr_hw_segs++;
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}
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nr_phys_segs++;
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bvprv = bv;
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seg_size = bv->bv_len;
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highprv = high;
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}
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if (nr_hw_segs == 1 &&
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hw_seg_size > rq->bio->bi_hw_front_size)
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rq->bio->bi_hw_front_size = hw_seg_size;
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if (hw_seg_size > rq->biotail->bi_hw_back_size)
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rq->biotail->bi_hw_back_size = hw_seg_size;
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rq->nr_phys_segments = nr_phys_segs;
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rq->nr_hw_segments = nr_hw_segs;
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}
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void blk_recount_segments(struct request_queue *q, struct bio *bio)
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{
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struct request rq;
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struct bio *nxt = bio->bi_next;
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rq.q = q;
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rq.bio = rq.biotail = bio;
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bio->bi_next = NULL;
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blk_recalc_rq_segments(&rq);
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bio->bi_next = nxt;
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bio->bi_phys_segments = rq.nr_phys_segments;
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bio->bi_hw_segments = rq.nr_hw_segments;
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bio->bi_flags |= (1 << BIO_SEG_VALID);
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}
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EXPORT_SYMBOL(blk_recount_segments);
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static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio,
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struct bio *nxt)
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{
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if (!(q->queue_flags & (1 << QUEUE_FLAG_CLUSTER)))
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return 0;
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if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)))
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return 0;
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if (bio->bi_size + nxt->bi_size > q->max_segment_size)
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return 0;
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/*
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* bio and nxt are contigous in memory, check if the queue allows
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* these two to be merged into one
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*/
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if (BIO_SEG_BOUNDARY(q, bio, nxt))
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return 1;
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return 0;
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}
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static int blk_hw_contig_segment(struct request_queue *q, struct bio *bio,
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struct bio *nxt)
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{
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if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
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blk_recount_segments(q, bio);
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if (unlikely(!bio_flagged(nxt, BIO_SEG_VALID)))
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blk_recount_segments(q, nxt);
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if (!BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)) ||
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BIOVEC_VIRT_OVERSIZE(bio->bi_hw_back_size + nxt->bi_hw_front_size))
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return 0;
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if (bio->bi_hw_back_size + nxt->bi_hw_front_size > q->max_segment_size)
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return 0;
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return 1;
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}
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/*
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* map a request to scatterlist, return number of sg entries setup. Caller
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* must make sure sg can hold rq->nr_phys_segments entries
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*/
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int blk_rq_map_sg(struct request_queue *q, struct request *rq,
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struct scatterlist *sglist)
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{
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struct bio_vec *bvec, *bvprv;
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struct req_iterator iter;
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struct scatterlist *sg;
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int nsegs, cluster;
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nsegs = 0;
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cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
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/*
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* for each bio in rq
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*/
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bvprv = NULL;
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sg = NULL;
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rq_for_each_segment(bvec, rq, iter) {
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int nbytes = bvec->bv_len;
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if (bvprv && cluster) {
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if (sg->length + nbytes > q->max_segment_size)
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goto new_segment;
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if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec))
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goto new_segment;
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if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec))
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goto new_segment;
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sg->length += nbytes;
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} else {
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new_segment:
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if (!sg)
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sg = sglist;
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else {
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/*
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* If the driver previously mapped a shorter
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* list, we could see a termination bit
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* prematurely unless it fully inits the sg
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* table on each mapping. We KNOW that there
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* must be more entries here or the driver
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* would be buggy, so force clear the
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* termination bit to avoid doing a full
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* sg_init_table() in drivers for each command.
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*/
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sg->page_link &= ~0x02;
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sg = sg_next(sg);
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}
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sg_set_page(sg, bvec->bv_page, nbytes, bvec->bv_offset);
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nsegs++;
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}
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bvprv = bvec;
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} /* segments in rq */
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if (q->dma_drain_size) {
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sg->page_link &= ~0x02;
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sg = sg_next(sg);
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sg_set_page(sg, virt_to_page(q->dma_drain_buffer),
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q->dma_drain_size,
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((unsigned long)q->dma_drain_buffer) &
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(PAGE_SIZE - 1));
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nsegs++;
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}
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if (sg)
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sg_mark_end(sg);
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return nsegs;
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}
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EXPORT_SYMBOL(blk_rq_map_sg);
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static inline int ll_new_mergeable(struct request_queue *q,
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struct request *req,
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struct bio *bio)
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{
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int nr_phys_segs = bio_phys_segments(q, bio);
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if (req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) {
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req->cmd_flags |= REQ_NOMERGE;
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if (req == q->last_merge)
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q->last_merge = NULL;
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return 0;
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}
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/*
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* A hw segment is just getting larger, bump just the phys
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* counter.
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*/
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req->nr_phys_segments += nr_phys_segs;
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return 1;
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}
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static inline int ll_new_hw_segment(struct request_queue *q,
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struct request *req,
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struct bio *bio)
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{
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int nr_hw_segs = bio_hw_segments(q, bio);
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int nr_phys_segs = bio_phys_segments(q, bio);
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if (req->nr_hw_segments + nr_hw_segs > q->max_hw_segments
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|| req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) {
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req->cmd_flags |= REQ_NOMERGE;
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if (req == q->last_merge)
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q->last_merge = NULL;
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return 0;
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}
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/*
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* This will form the start of a new hw segment. Bump both
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* counters.
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*/
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req->nr_hw_segments += nr_hw_segs;
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req->nr_phys_segments += nr_phys_segs;
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return 1;
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}
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int ll_back_merge_fn(struct request_queue *q, struct request *req,
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struct bio *bio)
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{
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unsigned short max_sectors;
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int len;
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if (unlikely(blk_pc_request(req)))
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max_sectors = q->max_hw_sectors;
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else
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max_sectors = q->max_sectors;
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if (req->nr_sectors + bio_sectors(bio) > max_sectors) {
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req->cmd_flags |= REQ_NOMERGE;
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if (req == q->last_merge)
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q->last_merge = NULL;
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return 0;
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}
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if (unlikely(!bio_flagged(req->biotail, BIO_SEG_VALID)))
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blk_recount_segments(q, req->biotail);
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if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
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blk_recount_segments(q, bio);
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len = req->biotail->bi_hw_back_size + bio->bi_hw_front_size;
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if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req->biotail), __BVEC_START(bio)) &&
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!BIOVEC_VIRT_OVERSIZE(len)) {
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int mergeable = ll_new_mergeable(q, req, bio);
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if (mergeable) {
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if (req->nr_hw_segments == 1)
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req->bio->bi_hw_front_size = len;
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if (bio->bi_hw_segments == 1)
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bio->bi_hw_back_size = len;
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}
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return mergeable;
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}
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return ll_new_hw_segment(q, req, bio);
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}
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static int ll_front_merge_fn(struct request_queue *q, struct request *req,
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struct bio *bio)
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{
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unsigned short max_sectors;
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int len;
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if (unlikely(blk_pc_request(req)))
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max_sectors = q->max_hw_sectors;
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else
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max_sectors = q->max_sectors;
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if (req->nr_sectors + bio_sectors(bio) > max_sectors) {
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req->cmd_flags |= REQ_NOMERGE;
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if (req == q->last_merge)
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q->last_merge = NULL;
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return 0;
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}
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len = bio->bi_hw_back_size + req->bio->bi_hw_front_size;
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if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
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blk_recount_segments(q, bio);
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if (unlikely(!bio_flagged(req->bio, BIO_SEG_VALID)))
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blk_recount_segments(q, req->bio);
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if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(req->bio)) &&
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!BIOVEC_VIRT_OVERSIZE(len)) {
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int mergeable = ll_new_mergeable(q, req, bio);
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if (mergeable) {
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if (bio->bi_hw_segments == 1)
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bio->bi_hw_front_size = len;
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if (req->nr_hw_segments == 1)
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req->biotail->bi_hw_back_size = len;
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}
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return mergeable;
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}
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return ll_new_hw_segment(q, req, bio);
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}
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static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
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struct request *next)
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{
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int total_phys_segments;
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int total_hw_segments;
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/*
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* First check if the either of the requests are re-queued
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* requests. Can't merge them if they are.
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*/
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if (req->special || next->special)
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return 0;
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/*
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* Will it become too large?
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*/
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if ((req->nr_sectors + next->nr_sectors) > q->max_sectors)
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return 0;
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total_phys_segments = req->nr_phys_segments + next->nr_phys_segments;
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if (blk_phys_contig_segment(q, req->biotail, next->bio))
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total_phys_segments--;
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if (total_phys_segments > q->max_phys_segments)
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return 0;
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total_hw_segments = req->nr_hw_segments + next->nr_hw_segments;
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if (blk_hw_contig_segment(q, req->biotail, next->bio)) {
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int len = req->biotail->bi_hw_back_size + next->bio->bi_hw_front_size;
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/*
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* propagate the combined length to the end of the requests
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*/
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if (req->nr_hw_segments == 1)
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req->bio->bi_hw_front_size = len;
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if (next->nr_hw_segments == 1)
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next->biotail->bi_hw_back_size = len;
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total_hw_segments--;
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}
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if (total_hw_segments > q->max_hw_segments)
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return 0;
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/* Merge is OK... */
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req->nr_phys_segments = total_phys_segments;
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req->nr_hw_segments = total_hw_segments;
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return 1;
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}
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/*
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* "plug" the device if there are no outstanding requests: this will
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* force the transfer to start only after we have put all the requests
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@ -1409,84 +1038,6 @@ void blk_put_request(struct request *req)
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EXPORT_SYMBOL(blk_put_request);
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/*
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* Has to be called with the request spinlock acquired
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*/
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static int attempt_merge(struct request_queue *q, struct request *req,
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struct request *next)
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{
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if (!rq_mergeable(req) || !rq_mergeable(next))
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return 0;
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/*
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* not contiguous
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*/
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if (req->sector + req->nr_sectors != next->sector)
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return 0;
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if (rq_data_dir(req) != rq_data_dir(next)
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|| req->rq_disk != next->rq_disk
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|| next->special)
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return 0;
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/*
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* If we are allowed to merge, then append bio list
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* from next to rq and release next. merge_requests_fn
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* will have updated segment counts, update sector
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* counts here.
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*/
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if (!ll_merge_requests_fn(q, req, next))
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return 0;
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/*
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* At this point we have either done a back merge
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* or front merge. We need the smaller start_time of
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* the merged requests to be the current request
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* for accounting purposes.
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*/
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if (time_after(req->start_time, next->start_time))
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req->start_time = next->start_time;
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req->biotail->bi_next = next->bio;
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req->biotail = next->biotail;
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req->nr_sectors = req->hard_nr_sectors += next->hard_nr_sectors;
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elv_merge_requests(q, req, next);
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if (req->rq_disk) {
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disk_round_stats(req->rq_disk);
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req->rq_disk->in_flight--;
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}
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req->ioprio = ioprio_best(req->ioprio, next->ioprio);
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__blk_put_request(q, next);
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return 1;
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}
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static inline int attempt_back_merge(struct request_queue *q,
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struct request *rq)
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{
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struct request *next = elv_latter_request(q, rq);
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if (next)
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return attempt_merge(q, rq, next);
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||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
static inline 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;
|
||||
}
|
||||
|
||||
void init_request_from_bio(struct request *req, struct bio *bio)
|
||||
{
|
||||
req->cmd_type = REQ_TYPE_FS;
|
||||
@ -1938,35 +1489,6 @@ void submit_bio(int rw, struct bio *bio)
|
||||
|
||||
EXPORT_SYMBOL(submit_bio);
|
||||
|
||||
static void blk_recalc_rq_sectors(struct request *rq, int nsect)
|
||||
{
|
||||
if (blk_fs_request(rq)) {
|
||||
rq->hard_sector += nsect;
|
||||
rq->hard_nr_sectors -= nsect;
|
||||
|
||||
/*
|
||||
* Move the I/O submission pointers ahead if required.
|
||||
*/
|
||||
if ((rq->nr_sectors >= rq->hard_nr_sectors) &&
|
||||
(rq->sector <= rq->hard_sector)) {
|
||||
rq->sector = rq->hard_sector;
|
||||
rq->nr_sectors = rq->hard_nr_sectors;
|
||||
rq->hard_cur_sectors = bio_cur_sectors(rq->bio);
|
||||
rq->current_nr_sectors = rq->hard_cur_sectors;
|
||||
rq->buffer = bio_data(rq->bio);
|
||||
}
|
||||
|
||||
/*
|
||||
* if total number of sectors is less than the first segment
|
||||
* size, something has gone terribly wrong
|
||||
*/
|
||||
if (rq->nr_sectors < rq->current_nr_sectors) {
|
||||
printk("blk: request botched\n");
|
||||
rq->nr_sectors = rq->current_nr_sectors;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* __end_that_request_first - end I/O on a request
|
||||
* @req: the request being processed
|
||||
|
||||
485
block/blk-merge.c
Normal file
485
block/blk-merge.c
Normal file
@ -0,0 +1,485 @@
|
||||
/*
|
||||
* 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 "blk.h"
|
||||
|
||||
void blk_recalc_rq_sectors(struct request *rq, int nsect)
|
||||
{
|
||||
if (blk_fs_request(rq)) {
|
||||
rq->hard_sector += nsect;
|
||||
rq->hard_nr_sectors -= nsect;
|
||||
|
||||
/*
|
||||
* Move the I/O submission pointers ahead if required.
|
||||
*/
|
||||
if ((rq->nr_sectors >= rq->hard_nr_sectors) &&
|
||||
(rq->sector <= rq->hard_sector)) {
|
||||
rq->sector = rq->hard_sector;
|
||||
rq->nr_sectors = rq->hard_nr_sectors;
|
||||
rq->hard_cur_sectors = bio_cur_sectors(rq->bio);
|
||||
rq->current_nr_sectors = rq->hard_cur_sectors;
|
||||
rq->buffer = bio_data(rq->bio);
|
||||
}
|
||||
|
||||
/*
|
||||
* if total number of sectors is less than the first segment
|
||||
* size, something has gone terribly wrong
|
||||
*/
|
||||
if (rq->nr_sectors < rq->current_nr_sectors) {
|
||||
printk("blk: request botched\n");
|
||||
rq->nr_sectors = rq->current_nr_sectors;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
void blk_recalc_rq_segments(struct request *rq)
|
||||
{
|
||||
int nr_phys_segs;
|
||||
int nr_hw_segs;
|
||||
unsigned int phys_size;
|
||||
unsigned int hw_size;
|
||||
struct bio_vec *bv, *bvprv = NULL;
|
||||
int seg_size;
|
||||
int hw_seg_size;
|
||||
int cluster;
|
||||
struct req_iterator iter;
|
||||
int high, highprv = 1;
|
||||
struct request_queue *q = rq->q;
|
||||
|
||||
if (!rq->bio)
|
||||
return;
|
||||
|
||||
cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
|
||||
hw_seg_size = seg_size = 0;
|
||||
phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0;
|
||||
rq_for_each_segment(bv, rq, iter) {
|
||||
/*
|
||||
* 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) > q->bounce_pfn;
|
||||
if (high || highprv)
|
||||
goto new_hw_segment;
|
||||
if (cluster) {
|
||||
if (seg_size + bv->bv_len > q->max_segment_size)
|
||||
goto new_segment;
|
||||
if (!BIOVEC_PHYS_MERGEABLE(bvprv, bv))
|
||||
goto new_segment;
|
||||
if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bv))
|
||||
goto new_segment;
|
||||
if (BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len))
|
||||
goto new_hw_segment;
|
||||
|
||||
seg_size += bv->bv_len;
|
||||
hw_seg_size += bv->bv_len;
|
||||
bvprv = bv;
|
||||
continue;
|
||||
}
|
||||
new_segment:
|
||||
if (BIOVEC_VIRT_MERGEABLE(bvprv, bv) &&
|
||||
!BIOVEC_VIRT_OVERSIZE(hw_seg_size + bv->bv_len))
|
||||
hw_seg_size += bv->bv_len;
|
||||
else {
|
||||
new_hw_segment:
|
||||
if (nr_hw_segs == 1 &&
|
||||
hw_seg_size > rq->bio->bi_hw_front_size)
|
||||
rq->bio->bi_hw_front_size = hw_seg_size;
|
||||
hw_seg_size = BIOVEC_VIRT_START_SIZE(bv) + bv->bv_len;
|
||||
nr_hw_segs++;
|
||||
}
|
||||
|
||||
nr_phys_segs++;
|
||||
bvprv = bv;
|
||||
seg_size = bv->bv_len;
|
||||
highprv = high;
|
||||
}
|
||||
|
||||
if (nr_hw_segs == 1 &&
|
||||
hw_seg_size > rq->bio->bi_hw_front_size)
|
||||
rq->bio->bi_hw_front_size = hw_seg_size;
|
||||
if (hw_seg_size > rq->biotail->bi_hw_back_size)
|
||||
rq->biotail->bi_hw_back_size = hw_seg_size;
|
||||
rq->nr_phys_segments = nr_phys_segs;
|
||||
rq->nr_hw_segments = nr_hw_segs;
|
||||
}
|
||||
|
||||
void blk_recount_segments(struct request_queue *q, struct bio *bio)
|
||||
{
|
||||
struct request rq;
|
||||
struct bio *nxt = bio->bi_next;
|
||||
rq.q = q;
|
||||
rq.bio = rq.biotail = bio;
|
||||
bio->bi_next = NULL;
|
||||
blk_recalc_rq_segments(&rq);
|
||||
bio->bi_next = nxt;
|
||||
bio->bi_phys_segments = rq.nr_phys_segments;
|
||||
bio->bi_hw_segments = rq.nr_hw_segments;
|
||||
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 (!(q->queue_flags & (1 << QUEUE_FLAG_CLUSTER)))
|
||||
return 0;
|
||||
|
||||
if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)))
|
||||
return 0;
|
||||
if (bio->bi_size + nxt->bi_size > q->max_segment_size)
|
||||
return 0;
|
||||
|
||||
/*
|
||||
* bio and nxt are contigous 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 int blk_hw_contig_segment(struct request_queue *q, struct bio *bio,
|
||||
struct bio *nxt)
|
||||
{
|
||||
if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
|
||||
blk_recount_segments(q, bio);
|
||||
if (unlikely(!bio_flagged(nxt, BIO_SEG_VALID)))
|
||||
blk_recount_segments(q, nxt);
|
||||
if (!BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)) ||
|
||||
BIOVEC_VIRT_OVERSIZE(bio->bi_hw_back_size + nxt->bi_hw_front_size))
|
||||
return 0;
|
||||
if (bio->bi_hw_back_size + nxt->bi_hw_front_size > q->max_segment_size)
|
||||
return 0;
|
||||
|
||||
return 1;
|
||||
}
|
||||
|
||||
/*
|
||||
* 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 = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
|
||||
|
||||
/*
|
||||
* for each bio in rq
|
||||
*/
|
||||
bvprv = NULL;
|
||||
sg = NULL;
|
||||
rq_for_each_segment(bvec, rq, iter) {
|
||||
int nbytes = bvec->bv_len;
|
||||
|
||||
if (bvprv && cluster) {
|
||||
if (sg->length + nbytes > q->max_segment_size)
|
||||
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->page_link &= ~0x02;
|
||||
sg = sg_next(sg);
|
||||
}
|
||||
|
||||
sg_set_page(sg, bvec->bv_page, nbytes, bvec->bv_offset);
|
||||
nsegs++;
|
||||
}
|
||||
bvprv = bvec;
|
||||
} /* segments in rq */
|
||||
|
||||
if (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++;
|
||||
}
|
||||
|
||||
if (sg)
|
||||
sg_mark_end(sg);
|
||||
|
||||
return nsegs;
|
||||
}
|
||||
|
||||
EXPORT_SYMBOL(blk_rq_map_sg);
|
||||
|
||||
static inline int ll_new_mergeable(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 > q->max_phys_segments) {
|
||||
req->cmd_flags |= REQ_NOMERGE;
|
||||
if (req == q->last_merge)
|
||||
q->last_merge = NULL;
|
||||
return 0;
|
||||
}
|
||||
|
||||
/*
|
||||
* A hw segment is just getting larger, bump just the phys
|
||||
* counter.
|
||||
*/
|
||||
req->nr_phys_segments += nr_phys_segs;
|
||||
return 1;
|
||||
}
|
||||
|
||||
static inline int ll_new_hw_segment(struct request_queue *q,
|
||||
struct request *req,
|
||||
struct bio *bio)
|
||||
{
|
||||
int nr_hw_segs = bio_hw_segments(q, bio);
|
||||
int nr_phys_segs = bio_phys_segments(q, bio);
|
||||
|
||||
if (req->nr_hw_segments + nr_hw_segs > q->max_hw_segments
|
||||
|| req->nr_phys_segments + nr_phys_segs > q->max_phys_segments) {
|
||||
req->cmd_flags |= REQ_NOMERGE;
|
||||
if (req == q->last_merge)
|
||||
q->last_merge = NULL;
|
||||
return 0;
|
||||
}
|
||||
|
||||
/*
|
||||
* This will form the start of a new hw segment. Bump both
|
||||
* counters.
|
||||
*/
|
||||
req->nr_hw_segments += nr_hw_segs;
|
||||
req->nr_phys_segments += nr_phys_segs;
|
||||
return 1;
|
||||
}
|
||||
|
||||
int ll_back_merge_fn(struct request_queue *q, struct request *req,
|
||||
struct bio *bio)
|
||||
{
|
||||
unsigned short max_sectors;
|
||||
int len;
|
||||
|
||||
if (unlikely(blk_pc_request(req)))
|
||||
max_sectors = q->max_hw_sectors;
|
||||
else
|
||||
max_sectors = q->max_sectors;
|
||||
|
||||
if (req->nr_sectors + bio_sectors(bio) > max_sectors) {
|
||||
req->cmd_flags |= REQ_NOMERGE;
|
||||
if (req == q->last_merge)
|
||||
q->last_merge = NULL;
|
||||
return 0;
|
||||
}
|
||||
if (unlikely(!bio_flagged(req->biotail, BIO_SEG_VALID)))
|
||||
blk_recount_segments(q, req->biotail);
|
||||
if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
|
||||
blk_recount_segments(q, bio);
|
||||
len = req->biotail->bi_hw_back_size + bio->bi_hw_front_size;
|
||||
if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req->biotail), __BVEC_START(bio)) &&
|
||||
!BIOVEC_VIRT_OVERSIZE(len)) {
|
||||
int mergeable = ll_new_mergeable(q, req, bio);
|
||||
|
||||
if (mergeable) {
|
||||
if (req->nr_hw_segments == 1)
|
||||
req->bio->bi_hw_front_size = len;
|
||||
if (bio->bi_hw_segments == 1)
|
||||
bio->bi_hw_back_size = len;
|
||||
}
|
||||
return mergeable;
|
||||
}
|
||||
|
||||
return ll_new_hw_segment(q, req, bio);
|
||||
}
|
||||
|
||||
int ll_front_merge_fn(struct request_queue *q, struct request *req,
|
||||
struct bio *bio)
|
||||
{
|
||||
unsigned short max_sectors;
|
||||
int len;
|
||||
|
||||
if (unlikely(blk_pc_request(req)))
|
||||
max_sectors = q->max_hw_sectors;
|
||||
else
|
||||
max_sectors = q->max_sectors;
|
||||
|
||||
|
||||
if (req->nr_sectors + bio_sectors(bio) > max_sectors) {
|
||||
req->cmd_flags |= REQ_NOMERGE;
|
||||
if (req == q->last_merge)
|
||||
q->last_merge = NULL;
|
||||
return 0;
|
||||
}
|
||||
len = bio->bi_hw_back_size + req->bio->bi_hw_front_size;
|
||||
if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
|
||||
blk_recount_segments(q, bio);
|
||||
if (unlikely(!bio_flagged(req->bio, BIO_SEG_VALID)))
|
||||
blk_recount_segments(q, req->bio);
|
||||
if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(req->bio)) &&
|
||||
!BIOVEC_VIRT_OVERSIZE(len)) {
|
||||
int mergeable = ll_new_mergeable(q, req, bio);
|
||||
|
||||
if (mergeable) {
|
||||
if (bio->bi_hw_segments == 1)
|
||||
bio->bi_hw_front_size = len;
|
||||
if (req->nr_hw_segments == 1)
|
||||
req->biotail->bi_hw_back_size = len;
|
||||
}
|
||||
return mergeable;
|
||||
}
|
||||
|
||||
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;
|
||||
int total_hw_segments;
|
||||
|
||||
/*
|
||||
* 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 ((req->nr_sectors + next->nr_sectors) > q->max_sectors)
|
||||
return 0;
|
||||
|
||||
total_phys_segments = req->nr_phys_segments + next->nr_phys_segments;
|
||||
if (blk_phys_contig_segment(q, req->biotail, next->bio))
|
||||
total_phys_segments--;
|
||||
|
||||
if (total_phys_segments > q->max_phys_segments)
|
||||
return 0;
|
||||
|
||||
total_hw_segments = req->nr_hw_segments + next->nr_hw_segments;
|
||||
if (blk_hw_contig_segment(q, req->biotail, next->bio)) {
|
||||
int len = req->biotail->bi_hw_back_size + next->bio->bi_hw_front_size;
|
||||
/*
|
||||
* propagate the combined length to the end of the requests
|
||||
*/
|
||||
if (req->nr_hw_segments == 1)
|
||||
req->bio->bi_hw_front_size = len;
|
||||
if (next->nr_hw_segments == 1)
|
||||
next->biotail->bi_hw_back_size = len;
|
||||
total_hw_segments--;
|
||||
}
|
||||
|
||||
if (total_hw_segments > q->max_hw_segments)
|
||||
return 0;
|
||||
|
||||
/* Merge is OK... */
|
||||
req->nr_phys_segments = total_phys_segments;
|
||||
req->nr_hw_segments = total_hw_segments;
|
||||
return 1;
|
||||
}
|
||||
|
||||
/*
|
||||
* 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;
|
||||
|
||||
/*
|
||||
* not contiguous
|
||||
*/
|
||||
if (req->sector + req->nr_sectors != next->sector)
|
||||
return 0;
|
||||
|
||||
if (rq_data_dir(req) != rq_data_dir(next)
|
||||
|| req->rq_disk != next->rq_disk
|
||||
|| next->special)
|
||||
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;
|
||||
|
||||
/*
|
||||
* 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->nr_sectors = req->hard_nr_sectors += next->hard_nr_sectors;
|
||||
|
||||
elv_merge_requests(q, req, next);
|
||||
|
||||
if (req->rq_disk) {
|
||||
disk_round_stats(req->rq_disk);
|
||||
req->rq_disk->in_flight--;
|
||||
}
|
||||
|
||||
req->ioprio = ioprio_best(req->ioprio, next->ioprio);
|
||||
|
||||
__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;
|
||||
}
|
||||
11
block/blk.h
11
block/blk.h
@ -14,8 +14,6 @@ void rq_init(struct request_queue *q, struct request *rq);
|
||||
void init_request_from_bio(struct request *req, struct bio *bio);
|
||||
void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
|
||||
struct bio *bio);
|
||||
int ll_back_merge_fn(struct request_queue *q, struct request *req,
|
||||
struct bio *bio);
|
||||
void __blk_queue_free_tags(struct request_queue *q);
|
||||
|
||||
void blk_unplug_work(struct work_struct *work);
|
||||
@ -23,6 +21,15 @@ void blk_unplug_timeout(unsigned long data);
|
||||
|
||||
struct io_context *current_io_context(gfp_t gfp_flags, int node);
|
||||
|
||||
int ll_back_merge_fn(struct request_queue *q, struct request *req,
|
||||
struct bio *bio);
|
||||
int ll_front_merge_fn(struct request_queue *q, struct request *req,
|
||||
struct bio *bio);
|
||||
int attempt_back_merge(struct request_queue *q, struct request *rq);
|
||||
int attempt_front_merge(struct request_queue *q, struct request *rq);
|
||||
void blk_recalc_rq_segments(struct request *rq);
|
||||
void blk_recalc_rq_sectors(struct request *rq, int nsect);
|
||||
|
||||
void blk_queue_congestion_threshold(struct request_queue *q);
|
||||
|
||||
/*
|
||||
|
||||
Loading…
Reference in New Issue
Block a user