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Commit d6d48196 authored by Jens Axboe's avatar Jens Axboe
Browse files

block: ll_rw_blk.c split, add blk-merge.c 



Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent db1d08c6

block/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -4,7 +4,7 @@ 


obj-$(CONFIG_BLOCK) := elevator.o blk-core.o blk-tag.o blk-sysfs.o \

			blk-barrier.o blk-settings.o blk-ioc.o blk-map.o \

			blk-exec.o ioctl.o genhd.o scsi_ioctl.o

			blk-exec.o blk-merge.o ioctl.o genhd.o scsi_ioctl.o



obj-$(CONFIG_BLK_DEV_BSG)	+= bsg.o

obj-$(CONFIG_IOSCHED_NOOP)	+= noop-iosched.o

block/blk-core.c

+0 −478
Original line number Diff line number Diff line
@@ -29,7 +29,6 @@ 
#include <linux/cpu.h>

#include <linux/blktrace_api.h>

#include <linux/fault-inject.h>

#include <linux/scatterlist.h>



#include "blk.h"
@@ -181,376 +180,6 @@ void blk_dump_rq_flags(struct request *rq, char *msg) 


EXPORT_SYMBOL(blk_dump_rq_flags);



static 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);

}



static 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;

}



/*

 * "plug" the device if there are no outstanding requests: this will

 * force the transfer to start only after we have put all the requests
@@ -1409,84 +1038,6 @@ void blk_put_request(struct request *req) 


EXPORT_SYMBOL(blk_put_request);



/*

 * 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;

}



static inline 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;

}



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

block/blk-merge.c

0 → 100644
+485 −0

File added.

Preview size limit exceeded, changes collapsed.

block/blk.h

+9 −2
Original line number Diff line number Diff line
@@ -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);



/*