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authorJens Axboe <jens.axboe@oracle.com>2008-01-29 14:04:06 +0100
committerJens Axboe <jens.axboe@oracle.com>2008-01-29 21:55:12 +0100
commitd6d48196961729b79509dcaeeb0f0fb4fbb47d29 (patch)
treee80f5cdc7f0d682a46b816f5a489357f7d622d62
parentdb1d08c646e47f3c7835ecdabb51a906ec311f69 (diff)
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block: ll_rw_blk.c split, add blk-merge.c
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
-rw-r--r--block/Makefile2
-rw-r--r--block/blk-core.c478
-rw-r--r--block/blk-merge.c485
-rw-r--r--block/blk.h11
4 files changed, 495 insertions, 481 deletions
diff --git a/block/Makefile b/block/Makefile
index 2002046d0a9..5a43c7d7959 100644
--- a/block/Makefile
+++ b/block/Makefile
@@ -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
diff --git a/block/blk-core.c b/block/blk-core.c
index 99f4d641edf..8ff99440ee4 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -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
diff --git a/block/blk-merge.c b/block/blk-merge.c
new file mode 100644
index 00000000000..5023f0b0807
--- /dev/null
+++ b/block/blk-merge.c
@@ -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;
+}
diff --git a/block/blk.h b/block/blk.h
index 08339400719..ec898dd0c65 100644
--- a/block/blk.h
+++ b/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);
/*