rbd: Refactor bio cloning

Now that we've got drivers converted to the new immutable bvec
primitives, bio splitting becomes much easier - this is how the new
bio_split() will work. (Someone more familiar with the ceph code could
probably use bio_clone_fast() instead of bio_clone() here).

Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Yehuda Sadeh <yehuda@inktank.com>
Cc: Alex Elder <elder@inktank.com>
Cc: ceph-devel@vger.kernel.org

1 files changed, 2 insertions, 62 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 20e8ab35736b..3624368b910d 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -1173,73 +1173,13 @@ static struct bio *bio_clone_range(struct bio *bio_src,
                                         unsigned int len,
                                         gfp_t gfpmask)
 {
-        struct bio_vec bv;
-        struct bvec_iter iter;
-        struct bvec_iter end_iter;
-        unsigned int resid;
-        unsigned int voff;
-        unsigned short vcnt;
         struct bio *bio;
 
-        /* Handle the easy case for the caller */
-
-        if (!offset && len == bio_src->bi_iter.bi_size)
-                return bio_clone(bio_src, gfpmask);
-
-        if (WARN_ON_ONCE(!len))
-                return NULL;
-        if (WARN_ON_ONCE(len > bio_src->bi_iter.bi_size))
-                return NULL;
-        if (WARN_ON_ONCE(offset > bio_src->bi_iter.bi_size - len))
-                return NULL;
-
-        /* Find first affected segment... */
-
-        resid = offset;
-        bio_for_each_segment(bv, bio_src, iter) {
-                if (resid < bv.bv_len)
-                        break;
-                resid -= bv.bv_len;
-        }
-        voff = resid;
-
-        /* ...and the last affected segment */
-
-        resid += len;
-        __bio_for_each_segment(bv, bio_src, end_iter, iter) {
-                if (resid <= bv.bv_len)
-                        break;
-                resid -= bv.bv_len;
-        }
-        vcnt = end_iter.bi_idx = iter.bi_idx + 1;
-
-        /* Build the clone */
-
-        bio = bio_alloc(gfpmask, (unsigned int) vcnt);
+        bio = bio_clone(bio_src, gfpmask);
         if (!bio)
                 return NULL;    /* ENOMEM */
 
-        bio->bi_bdev = bio_src->bi_bdev;
-        bio->bi_iter.bi_sector = bio_src->bi_iter.bi_sector +
-                (offset >> SECTOR_SHIFT);
-        bio->bi_rw = bio_src->bi_rw;
-        bio->bi_flags |= 1 << BIO_CLONED;
-
-        /*
-         * Copy over our part of the bio_vec, then update the first
-         * and last (or only) entries.
-         */
-        memcpy(&bio->bi_io_vec[0], &bio_src->bi_io_vec[iter.bi_idx],
-                        vcnt * sizeof (struct bio_vec));
-        bio->bi_io_vec[0].bv_offset += voff;
-        if (vcnt > 1) {
-                bio->bi_io_vec[0].bv_len -= voff;
-                bio->bi_io_vec[vcnt - 1].bv_len = resid;
-        } else {
-                bio->bi_io_vec[0].bv_len = len;
-        }
-
-        bio->bi_vcnt = vcnt;
+        bio_advance(bio, offset);
         bio->bi_iter.bi_size = len;
 
         return bio;