On Thu, 2021-05-20 at 14:29 -0400, J. Bruce Fields wrote:
> On Thu, May 20, 2021 at 12:38:59PM -0400, trondmy@xxxxxxxxxx wrote:
> > From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> >
> > If we're unable to immediately recover all locks because the server
> > is
> > unable to immediately service our reclaim calls, then we want to
> > retry
> > after we've finished servicing all the other asynchronous
> > delegation
> > returns on our queue.
>
> So, there's a situation where the server can't service a reclaim
> until
> some other delegation is returned? I'm not seeing how that happens.
>
I can and I do... pNFS can be complicated...
> --b.
>
> >
> > Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> > ---
> > fs/nfs/delegation.c | 71 +++++++++++++++++++++++++++++++++++------
> > ----
> > fs/nfs/delegation.h | 1 +
> > fs/nfs/nfs4_fs.h | 1 +
> > 3 files changed, 58 insertions(+), 15 deletions(-)
> >
> > diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
> > index e6ec6f09ac6e..7c45ac3c3b0b 100644
> > --- a/fs/nfs/delegation.c
> > +++ b/fs/nfs/delegation.c
> > @@ -75,6 +75,13 @@ void nfs_mark_delegation_referenced(struct
> > nfs_delegation *delegation)
> > set_bit(NFS_DELEGATION_REFERENCED, &delegation->flags);
> > }
> >
> > +static void nfs_mark_return_delegation(struct nfs_server *server,
> > + struct nfs_delegation
> > *delegation)
> > +{
> > + set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
> > + set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client-
> > >cl_state);
> > +}
> > +
> > static bool
> > nfs4_is_valid_delegation(const struct nfs_delegation *delegation,
> > fmode_t flags)
> > @@ -293,6 +300,7 @@ nfs_start_delegation_return_locked(struct
> > nfs_inode *nfsi)
> > goto out;
> > spin_lock(&delegation->lock);
> > if (!test_and_set_bit(NFS_DELEGATION_RETURNING,
> > &delegation->flags)) {
> > + clear_bit(NFS_DELEGATION_RETURN_DELAYED,
> > &delegation->flags);
> > /* Refcount matched in nfs_end_delegation_return()
> > */
> > ret = nfs_get_delegation(delegation);
> > }
> > @@ -314,16 +322,17 @@ nfs_start_delegation_return(struct nfs_inode
> > *nfsi)
> > return delegation;
> > }
> >
> > -static void
> > -nfs_abort_delegation_return(struct nfs_delegation *delegation,
> > - struct nfs_client *clp)
> > +static void nfs_abort_delegation_return(struct nfs_delegation
> > *delegation,
> > + struct nfs_client *clp, int
> > err)
> > {
> >
> > spin_lock(&delegation->lock);
> > clear_bit(NFS_DELEGATION_RETURNING, &delegation->flags);
> > - set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
> > + if (err == -EAGAIN) {
> > + set_bit(NFS_DELEGATION_RETURN_DELAYED, &delegation-
> > >flags);
> > + set_bit(NFS4CLNT_DELEGRETURN_DELAYED, &clp-
> > >cl_state);
> > + }
> > spin_unlock(&delegation->lock);
> > - set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
> > }
> >
> > static struct nfs_delegation *
> > @@ -539,7 +548,7 @@ static int nfs_end_delegation_return(struct
> > inode *inode, struct nfs_delegation
> > } while (err == 0);
> >
> > if (err) {
> > - nfs_abort_delegation_return(delegation, clp);
> > + nfs_abort_delegation_return(delegation, clp, err);
> > goto out;
> > }
> >
> > @@ -568,6 +577,7 @@ static bool nfs_delegation_need_return(struct
> > nfs_delegation *delegation)
> > if (ret)
> > clear_bit(NFS_DELEGATION_RETURN_IF_CLOSED,
> > &delegation->flags);
> > if (test_bit(NFS_DELEGATION_RETURNING, &delegation->flags)
> > ||
> > + test_bit(NFS_DELEGATION_RETURN_DELAYED, &delegation-
> > >flags) ||
> > test_bit(NFS_DELEGATION_REVOKED, &delegation->flags))
> > ret = false;
> >
> > @@ -647,6 +657,38 @@ static int
> > nfs_server_return_marked_delegations(struct nfs_server *server,
> > return err;
> > }
> >
> > +static bool nfs_server_clear_delayed_delegations(struct nfs_server
> > *server)
> > +{
> > + struct nfs_delegation *d;
> > + bool ret = false;
> > +
> > + list_for_each_entry_rcu (d, &server->delegations,
> > super_list) {
> > + if (!test_bit(NFS_DELEGATION_RETURN_DELAYED, &d-
> > >flags))
> > + continue;
> > + nfs_mark_return_delegation(server, d);
> > + clear_bit(NFS_DELEGATION_RETURN_DELAYED, &d-
> > >flags);
> > + ret = true;
> > + }
> > + return ret;
> > +}
> > +
> > +static bool nfs_client_clear_delayed_delegations(struct nfs_client
> > *clp)
> > +{
> > + struct nfs_server *server;
> > + bool ret = false;
> > +
> > + if (!test_and_clear_bit(NFS4CLNT_DELEGRETURN_DELAYED, &clp-
> > >cl_state))
> > + goto out;
> > + rcu_read_lock();
> > + list_for_each_entry_rcu (server, &clp->cl_superblocks,
> > client_link) {
> > + if (nfs_server_clear_delayed_delegations(server))
> > + ret = true;
> > + }
> > + rcu_read_unlock();
> > +out:
> > + return ret;
> > +}
> > +
> > /**
> > * nfs_client_return_marked_delegations - return previously marked
> > delegations
> > * @clp: nfs_client to process
> > @@ -659,8 +701,14 @@ static int
> > nfs_server_return_marked_delegations(struct nfs_server *server,
> > */
> > int nfs_client_return_marked_delegations(struct nfs_client *clp)
> > {
> > - return nfs_client_for_each_server(clp,
> > - nfs_server_return_marked_delegations,
> > NULL);
> > + int err = nfs_client_for_each_server(
> > + clp, nfs_server_return_marked_delegations, NULL);
> > + if (err)
> > + return err;
> > + /* If a return was delayed, sleep to prevent hard looping
> > */
> > + if (nfs_client_clear_delayed_delegations(clp))
> > + ssleep(1);
> > + return 0;
> > }
> >
> > /**
> > @@ -775,13 +823,6 @@ static void
> > nfs_mark_return_if_closed_delegation(struct nfs_server *server,
> > set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client-
> > >cl_state);
> > }
> >
> > -static void nfs_mark_return_delegation(struct nfs_server *server,
> > - struct nfs_delegation *delegation)
> > -{
> > - set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
> > - set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client-
> > >cl_state);
> > -}
> > -
> > static bool nfs_server_mark_return_all_delegations(struct
> > nfs_server *server)
> > {
> > struct nfs_delegation *delegation;
> > diff --git a/fs/nfs/delegation.h b/fs/nfs/delegation.h
> > index c19b4fd20781..1c378992b7c0 100644
> > --- a/fs/nfs/delegation.h
> > +++ b/fs/nfs/delegation.h
> > @@ -36,6 +36,7 @@ enum {
> > NFS_DELEGATION_REVOKED,
> > NFS_DELEGATION_TEST_EXPIRED,
> > NFS_DELEGATION_INODE_FREEING,
> > + NFS_DELEGATION_RETURN_DELAYED,
> > };
> >
> > int nfs_inode_set_delegation(struct inode *inode, const struct
> > cred *cred,
> > diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
> > index 065cb04222a1..4c44322c2643 100644
> > --- a/fs/nfs/nfs4_fs.h
> > +++ b/fs/nfs/nfs4_fs.h
> > @@ -45,6 +45,7 @@ enum nfs4_client_state {
> > NFS4CLNT_RECALL_RUNNING,
> > NFS4CLNT_RECALL_ANY_LAYOUT_READ,
> > NFS4CLNT_RECALL_ANY_LAYOUT_RW,
> > + NFS4CLNT_DELEGRETURN_DELAYED,
> > };
> >
> > #define NFS4_RENEW_TIMEOUT 0x01
> > --
> > 2.31.1
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@xxxxxxxxxxxxxxx
