1 files changed, 36 insertions, 0 deletions

diff --git a/fs/nfs/callback_proc.c b/fs/nfs/callback_proc.c
index f731bbe7ac6a..6b342e82ebb3 100644
--- a/fs/nfs/callback_proc.c
+++ b/fs/nfs/callback_proc.c
@@ -104,6 +104,42 @@ out:
 
 #if defined(CONFIG_NFS_V4_1)
 
+/*
+ * Returns a pointer to a held 'struct nfs_client' that matches the server's
+ * address, major version number, and session ID.  It is the caller's
+ * responsibility to release the returned reference.
+ *
+ * Returns NULL if there are no connections with sessions, or if no session
+ * matches the one of interest.
+ */
+ static struct nfs_client *find_client_with_session(
+        const struct sockaddr *addr, u32 nfsversion,
+        struct nfs4_sessionid *sessionid)
+{
+        struct nfs_client *clp;
+
+        clp = nfs_find_client(addr, 4);
+        if (clp == NULL)
+                return NULL;
+
+        do {
+                struct nfs_client *prev = clp;
+
+                if (clp->cl_session != NULL) {
+                        if (memcmp(clp->cl_session->sess_id.data,
+                                        sessionid->data,
+                                        NFS4_MAX_SESSIONID_LEN) == 0) {
+                                /* Returns a held reference to clp */
+                                return clp;
+                        }
+                }
+                clp = nfs_find_client_next(prev);
+                nfs_put_client(prev);
+        } while (clp != NULL);
+
+        return NULL;
+}
+
 /* FIXME: validate args->cbs_{sequence,slot}id */
 /* FIXME: referring calls should be processed */
 unsigned nfs4_callback_sequence(struct cb_sequenceargs *args,