Didn't look at the code too hard, but this sounds good to me. I also realized that the userspace client isn't quite complete because it didn't send out FLAG_SYNC on a per-MDS-session basis, just for the last cap in its global dirty list. So thanks for that. :) https://tracker.ceph.com/issues/44916 On Thu, Apr 2, 2020 at 4:29 AM Jeff Layton <jlayton@xxxxxxxxxx> wrote: > > This is v2 of the patch I sent the other day to fix the problem of long > stalls when calling sync or syncfs. > > This set converts the mdsc->cap_dirty list to a per-session list, and > then has the only caller that looks at cap_dirty walk the list of > sessions and issue flushes for each session in turn. > > With this, we can use an empty s_cap_dirty list as an indicator that the > cap flush is the last one going to the session and can mark that one as > one we're waiting on so the MDS can expedite it. > > This also attempts to clarify some of the locking around s_cap_dirty, > and adds a FIXME comment to raise the question about locking around > s_cap_flushing. > > Jeff Layton (2): > ceph: convert mdsc->cap_dirty to a per-session list > ceph: request expedited service on session's last cap flush > > fs/ceph/caps.c | 72 +++++++++++++++++++++++++++++++++++++++----- > fs/ceph/mds_client.c | 2 +- > fs/ceph/mds_client.h | 5 +-- > fs/ceph/super.h | 21 +++++++++++-- > 4 files changed, 87 insertions(+), 13 deletions(-) > > -- > 2.25.1 >
