1 files changed, 30 insertions, 24 deletions

diff --git a/block/bio.c b/block/bio.c
index 3d4a072375ef..471d7382c7d1 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -748,6 +748,7 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page
                                 }
                         }
 
+                        bio->bi_iter.bi_size += len;
                         goto done;
                 }
 
@@ -764,29 +765,32 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page
                 return 0;
 
         /*
-         * we might lose a segment or two here, but rather that than
-         * make this too complex.
+         * setup the new entry, we might clear it again later if we
+         * cannot add the page
+         */
+        bvec = &bio->bi_io_vec[bio->bi_vcnt];
+        bvec->bv_page = page;
+        bvec->bv_len = len;
+        bvec->bv_offset = offset;
+        bio->bi_vcnt++;
+        bio->bi_phys_segments++;
+        bio->bi_iter.bi_size += len;
+
+        /*
+         * Perform a recount if the number of segments is greater
+         * than queue_max_segments(q).
          */
 
-        while (bio->bi_phys_segments >= queue_max_segments(q)) {
+        while (bio->bi_phys_segments > queue_max_segments(q)) {
 
                 if (retried_segments)
-                        return 0;
+                        goto failed;
 
                 retried_segments = 1;
                 blk_recount_segments(q, bio);
         }
 
         /*
-         * setup the new entry, we might clear it again later if we
-         * cannot add the page
-         */
-        bvec = &bio->bi_io_vec[bio->bi_vcnt];
-        bvec->bv_page = page;
-        bvec->bv_len = len;
-        bvec->bv_offset = offset;
-
-        /*
          * if queue has other restrictions (eg varying max sector size
          * depending on offset), it can specify a merge_bvec_fn in the
          * queue to get further control
@@ -795,7 +799,7 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page
                 struct bvec_merge_data bvm = {
                         .bi_bdev = bio->bi_bdev,
                         .bi_sector = bio->bi_iter.bi_sector,
-                        .bi_size = bio->bi_iter.bi_size,
+                        .bi_size = bio->bi_iter.bi_size - len,
                         .bi_rw = bio->bi_rw,
                 };
 
@@ -803,23 +807,25 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page
                  * merge_bvec_fn() returns number of bytes it can accept
                  * at this offset
                  */
-                if (q->merge_bvec_fn(q, &bvm, bvec) < bvec->bv_len) {
-                        bvec->bv_page = NULL;
-                        bvec->bv_len = 0;
-                        bvec->bv_offset = 0;
-                        return 0;
-                }
+                if (q->merge_bvec_fn(q, &bvm, bvec) < bvec->bv_len)
+                        goto failed;
         }
 
         /* If we may be able to merge these biovecs, force a recount */
-        if (bio->bi_vcnt && (BIOVEC_PHYS_MERGEABLE(bvec-1, bvec)))
+        if (bio->bi_vcnt > 1 && (BIOVEC_PHYS_MERGEABLE(bvec-1, bvec)))
                 bio->bi_flags &= ~(1 << BIO_SEG_VALID);
 
-        bio->bi_vcnt++;
-        bio->bi_phys_segments++;
  done:
-        bio->bi_iter.bi_size += len;
         return len;
+
+ failed:
+        bvec->bv_page = NULL;
+        bvec->bv_len = 0;
+        bvec->bv_offset = 0;
+        bio->bi_vcnt--;
+        bio->bi_iter.bi_size -= len;
+        blk_recount_segments(q, bio);
+        return 0;
 }
 
 /**