Re: [v3] ceph: add 'lazyio' mount option to kclient

Hi Xiubo,

One issue in caps.c:1014: ceph_adjust_caps_used_for_lazyio() maps
CACHE/BUFFER onto LAZYIO only while LAZYIO is in issued. The grant path
in handle_cap_grant() is fine — the writeback/invalidate wait fires
there. But after the revoke, ceph_check_caps() sees used as BUFFER/CACHE
with revoking as LAZYIO, (revoking & cap_used)==0, and ACKs immediately.
The MDS can then hand the cap to another client while dirty or stale
pages are still present.

Fix: extend the mapping to cover implemented, not just issued, so the
LAZYIO-revoking case holds until writeback and invalidation actually
complete. Also worth queuing writeback when revoking LAZYIO with
i_wrbuffer_ref set, matching the existing BUFFER path.

Minor: the commit message still says CEPH_FILE_MODE_LAZY is set in
ceph_init_file_info(); since v2 it's set in ceph_open()/ceph_atomic_open().

Could you respin?

--
Alex Markuze