[PATCH 15/22] rbd: Refactor bio cloning, don't clone biovecs

Kent Overstreet
2013-08-07T21:55:39Z

Now that we've got drivers converted to the new immutable bvec
primitives, bio splitting becomes much easier. In a few patches,
bio_clone() will be changed to share the old bio's bvec instead of
copying it, and bio_split() will do exactly what's being done 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
---
drivers/block/rbd.c | 64 ++---------------------------------------------------
1 file changed, 2 insertions(+), 62 deletions(-)

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index f99f347..efb082c 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -1167,73 +1167,13 @@ 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;
--
1.8.4.rc1