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.
--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
