On Mon, 2020-06-08 at 09:56 +0200, Ilya Dryomov wrote:
> osd_req_flags is overly general and doesn't suit its only user
> (read_from_replica option) well:
>
> - applying osd_req_flags in account_request() affects all OSD
> requests, including linger (i.e. watch and notify). However,
> linger requests should always go to the primary even though
> some of them are reads (e.g. notify has side effects but it
> is a read because it doesn't result in mutation on the OSDs).
>
> - calls to class methods that are reads are allowed to go to
> the replica, but most such calls issued for "rbd map" and/or
> exclusive lock transitions are requested to be resent to the
> primary via EAGAIN, doubling the latency.
>
> Get rid of global osd_req_flags and set read_from_replica flag
> only on specific OSD requests instead.
>
> Fixes: 8ad44d5e0d1e ("libceph: read_from_replica option")
> Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
> ---
> drivers/block/rbd.c | 4 +++-
> include/linux/ceph/libceph.h | 4 ++--
> net/ceph/ceph_common.c | 14 ++++++--------
> net/ceph/osd_client.c | 3 +--
> 4 files changed, 12 insertions(+), 13 deletions(-)
Looks reasonable:
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
