drop vmerge accounting

Remove hw_segments field from struct bio and struct request. Without virtual
merge accounting they have no purpose.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

8 files changed, 6 insertions, 69 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 1261516dd42a..2616cdd049a8 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2026,7 +2026,6 @@ void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
 
         if (bio_has_data(bio)) {
                 rq->nr_phys_segments = bio_phys_segments(q, bio);
-                rq->nr_hw_segments = bio_hw_segments(q, bio);
                 rq->buffer = bio_data(bio);
         }
         rq->current_nr_sectors = bio_cur_sectors(bio);
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 2c2a2ee716ec..d81d91419ff5 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -41,12 +41,9 @@ void blk_recalc_rq_sectors(struct request *rq, int nsect)
 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;
@@ -56,8 +53,8 @@ void blk_recalc_rq_segments(struct request *rq)
                 return;
 
         cluster = test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
-        hw_seg_size = seg_size = 0;
-        phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0;
+        seg_size = 0;
+        phys_size = nr_phys_segs = 0;
         rq_for_each_segment(bv, rq, iter) {
                 /*
                  * the trick here is making sure that a high page is never
@@ -76,30 +73,17 @@ void blk_recalc_rq_segments(struct request *rq)
                                 goto new_segment;
 
                         seg_size += bv->bv_len;
-                        hw_seg_size += bv->bv_len;
                         bvprv = bv;
                         continue;
                 }
 new_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 = 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)
@@ -112,7 +96,6 @@ void blk_recount_segments(struct request_queue *q, struct bio *bio)
         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);
@@ -255,10 +238,9 @@ 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
+        if (req->nr_phys_segments + nr_phys_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)
@@ -270,7 +252,6 @@ static inline int ll_new_hw_segment(struct request_queue *q,
          * 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;
 }
@@ -328,7 +309,6 @@ 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
@@ -350,14 +330,11 @@ static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
         if (total_phys_segments > q->max_phys_segments)
                 return 0;
 
-        total_hw_segments = req->nr_hw_segments + next->nr_hw_segments;
-
-        if (total_hw_segments > q->max_hw_segments)
+        if (total_phys_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;
 }
 
diff --git a/block/elevator.c b/block/elevator.c
index 4f5127054e3f..269615e6dbf5 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -790,7 +790,6 @@ struct request *elv_next_request(struct request_queue *q)
                          * device can handle
                          */
                         rq->nr_phys_segments++;
-                        rq->nr_hw_segments++;
                 }
 
                 if (!q->prep_rq_fn)
@@ -813,7 +812,6 @@ struct request *elv_next_request(struct request_queue *q)
                                  * so that we don't add it again
                                  */
                                 --rq->nr_phys_segments;
-                                --rq->nr_hw_segments;
                         }
 
                         rq = NULL;
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 03a5ab705c20..28a3869dcfd2 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1302,9 +1302,6 @@ static void sync_request_write(mddev_t *mddev, r1bio_t *r1_bio)
                                         sbio->bi_size = r1_bio->sectors << 9;
                                         sbio->bi_idx = 0;
                                         sbio->bi_phys_segments = 0;
-                                        sbio->bi_hw_segments = 0;
-                                        sbio->bi_hw_front_size = 0;
-                                        sbio->bi_hw_back_size = 0;
                                         sbio->bi_flags &= ~(BIO_POOL_MASK - 1);
                                         sbio->bi_flags |= 1 << BIO_UPTODATE;
                                         sbio->bi_next = NULL;
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index e34cd0e62473..0f40688503e7 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1345,9 +1345,6 @@ static void sync_request_write(mddev_t *mddev, r10bio_t *r10_bio)
                 tbio->bi_size = r10_bio->sectors << 9;
                 tbio->bi_idx = 0;
                 tbio->bi_phys_segments = 0;
-                tbio->bi_hw_segments = 0;
-                tbio->bi_hw_front_size = 0;
-                tbio->bi_hw_back_size = 0;
                 tbio->bi_flags &= ~(BIO_POOL_MASK - 1);
                 tbio->bi_flags |= 1 << BIO_UPTODATE;
                 tbio->bi_next = NULL;
diff --git a/fs/bio.c b/fs/bio.c
index 4ac7c59d1c6d..bee4deca774a 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -208,14 +208,6 @@ inline int bio_phys_segments(struct request_queue *q, struct bio *bio)
         return bio->bi_phys_segments;
 }
 
-inline int bio_hw_segments(struct request_queue *q, struct bio *bio)
-{
-        if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
-                blk_recount_segments(q, bio);
-
-        return bio->bi_hw_segments;
-}
-
 /**
  *      __bio_clone     -       clone a bio
  *      @bio: destination bio
@@ -350,7 +342,7 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page
          */
 
         while (bio->bi_phys_segments >= q->max_phys_segments
-               || bio->bi_hw_segments >= q->max_hw_segments) {
+               || bio->bi_phys_segments >= q->max_hw_segments) {
 
                 if (retried_segments)
                         return 0;
@@ -399,7 +391,6 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page
 
         bio->bi_vcnt++;
         bio->bi_phys_segments++;
-        bio->bi_hw_segments++;
  done:
         bio->bi_size += len;
         return len;
@@ -1381,7 +1372,6 @@ EXPORT_SYMBOL(bio_init);
 EXPORT_SYMBOL(__bio_clone);
 EXPORT_SYMBOL(bio_clone);
 EXPORT_SYMBOL(bio_phys_segments);
-EXPORT_SYMBOL(bio_hw_segments);
 EXPORT_SYMBOL(bio_add_page);
 EXPORT_SYMBOL(bio_add_pc_page);
 EXPORT_SYMBOL(bio_get_nr_vecs);
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 894d16ce0020..dfc3556d311c 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -77,21 +77,8 @@ struct bio {
          */
         unsigned short          bi_phys_segments;
 
-        /* Number of segments after physical and DMA remapping
-         * hardware coalescing is performed.
-         */
-        unsigned short          bi_hw_segments;
-
         unsigned int            bi_size;        /* residual I/O count */
 
-        /*
-         * To keep track of the max hw size, we account for the
-         * sizes of the first and last virtually mergeable segments
-         * in this bio
-         */
-        unsigned int            bi_hw_front_size;
-        unsigned int            bi_hw_back_size;
-
         unsigned int            bi_max_vecs;    /* max bvl_vecs we can hold */
 
         struct bio_vec          *bi_io_vec;     /* the actual vec list */
@@ -113,7 +100,7 @@ struct bio {
 #define BIO_UPTODATE    0       /* ok after I/O completion */
 #define BIO_RW_BLOCK    1       /* RW_AHEAD set, and read/write would block */
 #define BIO_EOF         2       /* out-out-bounds error */
-#define BIO_SEG_VALID   3       /* nr_hw_seg valid */
+#define BIO_SEG_VALID   3       /* bi_phys_segments valid */
 #define BIO_CLONED      4       /* doesn't own data */
 #define BIO_BOUNCED     5       /* bio is a bounce bio */
 #define BIO_USER_MAPPED 6       /* contains user pages */
@@ -324,7 +311,6 @@ extern void bio_free(struct bio *, struct bio_set *);
 extern void bio_endio(struct bio *, int);
 struct request_queue;
 extern int bio_phys_segments(struct request_queue *, struct bio *);
-extern int bio_hw_segments(struct request_queue *, struct bio *);
 
 extern void __bio_clone(struct bio *, struct bio *);
 extern struct bio *bio_clone(struct bio *, gfp_t);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 490ce458b031..1adb03827bd3 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -189,13 +189,6 @@ struct request {
          */
         unsigned short nr_phys_segments;
 
-        /* Number of scatter-gather addr+len pairs after
-         * physical and DMA remapping hardware coalescing is performed.
-         * This is the number of scatter-gather entries the driver
-         * will actually have to deal with after DMA mapping is done.
-         */
-        unsigned short nr_hw_segments;
-
         unsigned short ioprio;
 
         void *special;