On Thu, Jun 30, 2022 at 10:33 AM Yan, Zheng <ukernel@xxxxxxxxx> wrote: > > On Wed, Jun 29, 2022 at 8:08 PM Jeff Layton <jlayton@xxxxxxxxxx> wrote: > > > > Are you suggesting that the MDS ought to hold a cap message for an inode > > before its create request is processed? Note that the MDS won't even be > > aware that the inode even _exists_ at that point. As far as the MDS > > knows, it's just be a delegated inode number to the client. At what > > point does the MDS give up on holding such a cap request if the create > > request never comes in for some reason? > > > For an async request, MDS should not process it immediately. If there > is any wait when handling async request, it's mds bug. I suggest > tracking down any wait, and fix it. > I mean: For an async request, MDS should process it immediately. This is important for preserving request ordering. > > > I don't see the harm in making the client wait until it gets a create > > reply before sending a cap message. If we want to revert fbed7045f552 > > instead, we can do that, but it'll cause a regression until the MDS is > > fixed [1]. Regardless, we need to either take this patch or revert that > > one. > > > > I move that we take this patch for now to address the softlockups. Once > > the MDS is fixed we could revert this and fbed7045f552 without causing a > > regression. > > > > [1]: https://tracker.ceph.com/issues/54107 > > > > > > On Thu, 2022-06-09 at 10:15 +0800, Yan, Zheng wrote: > > > The recent series of patches that add "wait on async xxxx" at various > > > places do not seem correct. The correct fix should make mds avoid any > > > wait when handling async requests. > > > > > > > > > On Wed, Jun 8, 2022 at 12:56 PM Jeff Layton <jlayton@xxxxxxxxxx> wrote: > > > > > > > > Currently, we'll call ceph_check_caps, but if we're still waiting on the > > > > reply, we'll end up spinning around on the same inode in > > > > flush_dirty_session_caps. Wait for the async create reply before > > > > flushing caps. > > > > > > > > Fixes: fbed7045f552 (ceph: wait for async create reply before sending any cap messages) > > > > URL: https://tracker.ceph.com/issues/55823 > > > > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> > > > > --- > > > > fs/ceph/caps.c | 1 + > > > > 1 file changed, 1 insertion(+) > > > > > > > > I don't know if this will fix the tx queue stalls completely, but I > > > > haven't seen one with this patch in place. I think it makes sense on its > > > > own, either way. > > > > > > > > diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c > > > > index 0a48bf829671..5ecfff4b37c9 100644 > > > > --- a/fs/ceph/caps.c > > > > +++ b/fs/ceph/caps.c > > > > @@ -4389,6 +4389,7 @@ static void flush_dirty_session_caps(struct ceph_mds_session *s) > > > > ihold(inode); > > > > dout("flush_dirty_caps %llx.%llx\n", ceph_vinop(inode)); > > > > spin_unlock(&mdsc->cap_dirty_lock); > > > > + ceph_wait_on_async_create(inode); > > > > ceph_check_caps(ci, CHECK_CAPS_FLUSH, NULL); > > > > iput(inode); > > > > spin_lock(&mdsc->cap_dirty_lock); > > > > -- > > > > 2.36.1 > > > > > > > > -- > > Jeff Layton <jlayton@xxxxxxxxxx>
