block: fix missing bio back/front segment size setting in blk_recount_segments()

Commit 1e42807918d17e8c93bf14fbb74be84b141334c1 introduced a bug where we
don't get front/back segment sizes in the bio in blk_recount_segments().
Fix this by tracking the back bio as well as the front bio in
__blk_recalc_rq_segments(), this also cleans up the interface by getting
rid of the segment size pointer passing.

Tested-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 9 insertions, 16 deletions

diff --git a/block/blk-merge.c b/block/blk-merge.c
index a104593e70c..5a244f05360 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -39,14 +39,13 @@ void blk_recalc_rq_sectors(struct request *rq, int nsect)
 }
 
 static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
-                                             struct bio *bio,
-                                             unsigned int *seg_size_ptr)
+                                             struct bio *bio)
 {
         unsigned int phys_size;
         struct bio_vec *bv, *bvprv = NULL;
         int cluster, i, high, highprv = 1;
         unsigned int seg_size, nr_phys_segs;
-        struct bio *fbio;
+        struct bio *fbio, *bbio;
 
         if (!bio)
                 return 0;
@@ -87,26 +86,20 @@ new_segment:
                         seg_size = bv->bv_len;
                         highprv = high;
                 }
+                bbio = bio;
         }
 
-        if (seg_size_ptr)
-                *seg_size_ptr = seg_size;
+        if (nr_phys_segs == 1 && seg_size > fbio->bi_seg_front_size)
+                fbio->bi_seg_front_size = seg_size;
+        if (seg_size > bbio->bi_seg_back_size)
+                bbio->bi_seg_back_size = seg_size;
 
         return nr_phys_segs;
 }
 
 void blk_recalc_rq_segments(struct request *rq)
 {
-        unsigned int seg_size = 0, phys_segs;
-
-        phys_segs = __blk_recalc_rq_segments(rq->q, rq->bio, &seg_size);
-
-        if (phys_segs == 1 && seg_size > rq->bio->bi_seg_front_size)
-                rq->bio->bi_seg_front_size = seg_size;
-        if (seg_size > rq->biotail->bi_seg_back_size)
-                rq->biotail->bi_seg_back_size = seg_size;
-
-        rq->nr_phys_segments = phys_segs;
+        rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio);
 }
 
 void blk_recount_segments(struct request_queue *q, struct bio *bio)
@@ -114,7 +107,7 @@ void blk_recount_segments(struct request_queue *q, struct bio *bio)
         struct bio *nxt = bio->bi_next;
 
         bio->bi_next = NULL;
-        bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio, NULL);
+        bio->bi_phys_segments = __blk_recalc_rq_segments(q, bio);
         bio->bi_next = nxt;
         bio->bi_flags |= (1 << BIO_SEG_VALID);
 }