libceph, rbd: new bio handling code (aka don't clone bios)
The reason we clone bios is to be able to give each object request
(and consequently each ceph_osd_data/ceph_msg_data item) its own
pointer to a (list of) bio(s). The messenger then initializes its
cursor with cloned bio's ->bi_iter, so it knows where to start reading
from/writing to. That's all the cloned bios are used for: to determine
each object request's starting position in the provided data buffer.
Introduce ceph_bio_iter to do exactly that -- store position within bio
list (i.e. pointer to bio) + position within that bio (i.e. bvec_iter).
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
5 files changed