nfsd: Convert delegation counter to an atomic_long_t type

We want to convert to an atomic type so that we don't need to lock
across the call to alloc_init_deleg(). Then convert to a long type so
that we match the size of 'max_delegations'.

None of this is a problem today, but it will be once we remove
client_mutex protection.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 9c912c0..b421b51 100644 (file)
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -342,7 +342,7 @@ find_any_file(struct nfs4_file *f)
        return ret;
 }
 
-static int num_delegations;
+static atomic_long_t num_delegations;
 unsigned long max_delegations;
 
 /*
@@ -582,22 +582,23 @@ static struct nfs4_delegation *
 alloc_init_deleg(struct nfs4_client *clp, struct nfs4_ol_stateid *stp, struct svc_fh *current_fh)
 {
        struct nfs4_delegation *dp;
+       long n;
 
        dprintk("NFSD alloc_init_deleg\n");
-       if (num_delegations > max_delegations)
-               return NULL;
+       n = atomic_long_inc_return(&num_delegations);
+       if (n < 0 || n > max_delegations)
+               goto out_dec;
        if (delegation_blocked(&current_fh->fh_handle))
-               return NULL;
+               goto out_dec;
        dp = delegstateid(nfs4_alloc_stid(clp, deleg_slab));
        if (dp == NULL)
-               return dp;
+               goto out_dec;
        /*
         * delegation seqid's are never incremented.  The 4.1 special
         * meaning of seqid 0 isn't meaningful, really, but let's avoid
         * 0 anyway just for consistency and use 1:
         */
        dp->dl_stid.sc_stateid.si_generation = 1;
-       num_delegations++;
        INIT_LIST_HEAD(&dp->dl_perfile);
        INIT_LIST_HEAD(&dp->dl_perclnt);
        INIT_LIST_HEAD(&dp->dl_recall_lru);
@@ -605,6 +606,9 @@ alloc_init_deleg(struct nfs4_client *clp, struct nfs4_ol_stateid *stp, struct sv
        fh_copy_shallow(&dp->dl_fh, &current_fh->fh_handle);
        INIT_WORK(&dp->dl_recall.cb_work, nfsd4_run_cb_recall);
        return dp;
+out_dec:
+       atomic_long_dec(&num_delegations);
+       return NULL;
 }
 
 static void remove_stid(struct nfs4_stid *s)
@@ -627,7 +631,7 @@ nfs4_put_delegation(struct nfs4_delegation *dp)
                        put_nfs4_file(dp->dl_file);
                remove_stid(&dp->dl_stid);
                nfs4_free_stid(deleg_slab, &dp->dl_stid);
-               num_delegations--;
+               atomic_long_dec(&num_delegations);
        }
 }