Something still doesn't look quite right: a sequence operation
increments cl_count from 1 to 2; then, say, an exchangeid in another
thread expires the client, dropping cl_count from 2 to 1; then the
laundromat runs, sees cl_count 1, and decides it can expire the
client. Meanwhile, the original compound is still running.
Am I missing something?
--b.
On Wed, May 12, 2010 at 12:13:54AM +0300, Benny Halevy wrote:
> Get a refcount on the client on SEQUENCE,
> Release the refcount and renew the client when all respective compounds completed.
> Do not expire the client by the laundromat while in use.
> If the client was expired via another path, free it when the compounds
> complete and the refcount reaches 0.
>
> Note that unhash_client_locked must call list_del_init on cl_lru as
> it may be called twice for the same client (once from nfs4_laundromat
> and then from expire_client)
>
> Signed-off-by: Benny Halevy <bhalevy@xxxxxxxxxxx>
> ---
> fs/nfsd/nfs4state.c | 27 ++++++++++++++++++++++++---
> fs/nfsd/nfs4xdr.c | 3 ++-
> fs/nfsd/state.h | 1 +
> 3 files changed, 27 insertions(+), 4 deletions(-)
>
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 378ee86..1a8fb39 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -701,6 +701,22 @@ free_client(struct nfs4_client *clp)
> kfree(clp);
> }
>
> +void
> +release_session_client(struct nfsd4_session *session)
> +{
> + struct nfs4_client *clp = session->se_client;
> +
> + spin_lock(&client_lock);
> + BUG_ON(clp->cl_refcount <= 0);
> + if (--clp->cl_refcount <= 0) {
> + free_client(clp);
> + session->se_client = NULL;
> + } else if (clp->cl_refcount == 1)
> + renew_client_locked(clp);
> + spin_unlock(&client_lock);
> + nfsd4_put_session(session);
> +}
> +
> /* must be called under the client_lock */
> static inline void
> unhash_client_locked(struct nfs4_client *clp)
> @@ -1477,8 +1493,7 @@ out:
> /* Hold a session reference until done processing the compound. */
> if (cstate->session) {
> nfsd4_get_session(cstate->session);
> - /* Renew the clientid on success and on replay */
> - renew_client_locked(session->se_client);
> + session->se_client->cl_refcount++;
> }
> spin_unlock(&client_lock);
> dprintk("%s: return %d\n", __func__, ntohl(status));
> @@ -2599,7 +2614,13 @@ nfs4_laundromat(void)
> clientid_val = t;
> break;
> }
> - list_move(&clp->cl_lru, &reaplist);
> + if (clp->cl_refcount > 1) {
> + dprintk("NFSD: client in use (clientid %08x)\n",
> + clp->cl_clientid.cl_id);
> + continue;
> + }
> + unhash_client_locked(clp);
> + list_add(&clp->cl_lru, &reaplist);
> }
> spin_unlock(&client_lock);
> list_for_each_safe(pos, next, &reaplist) {
> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> index 5c2de47..126d0ca 100644
> --- a/fs/nfsd/nfs4xdr.c
> +++ b/fs/nfsd/nfs4xdr.c
> @@ -3313,7 +3313,8 @@ nfs4svc_encode_compoundres(struct svc_rqst *rqstp, __be32 *p, struct nfsd4_compo
> dprintk("%s: SET SLOT STATE TO AVAILABLE\n", __func__);
> cs->slot->sl_inuse = false;
> }
> - nfsd4_put_session(cs->session);
> + /* Renew the clientid on success and on replay */
> + release_session_client(cs->session);
> }
> return 1;
> }
> diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
> index 37e1dff..f263174 100644
> --- a/fs/nfsd/state.h
> +++ b/fs/nfsd/state.h
> @@ -419,6 +419,7 @@ extern int nfs4_has_reclaimed_state(const char *name, bool use_exchange_id);
> extern void nfsd4_recdir_purge_old(void);
> extern int nfsd4_create_clid_dir(struct nfs4_client *clp);
> extern void nfsd4_remove_clid_dir(struct nfs4_client *clp);
> +extern void release_session_client(struct nfsd4_session *);
>
> static inline void
> nfs4_put_stateowner(struct nfs4_stateowner *so)
> --
> 1.6.5.1
>
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