SUNRPC: Fix a lock recursion in the auth_gss downcall

 When we look up a new cred in the auth_gss downcall so that we can stuff
 the credcache, we do not want that lookup to queue up an upcall in order
 to initialise it. To do an upcall here not only redundant, but since we
 are already holding the inode->i_mutex, it will trigger a lock recursion.

 This patch allows rpcauth cache searches to indicate that they can cope
 with uninitialised credentials.

 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 10 insertions, 7 deletions

diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c
index 9ac1b8c26c01..1ca89c36da7a 100644
--- a/net/sunrpc/auth.c
+++ b/net/sunrpc/auth.c
@@ -184,7 +184,7 @@ rpcauth_gc_credcache(struct rpc_auth *auth, struct hlist_head *free)
  */
 struct rpc_cred *
 rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred,
-                int taskflags)
+                int flags)
 {
         struct rpc_cred_cache *cache = auth->au_credcache;
         HLIST_HEAD(free);
@@ -193,7 +193,7 @@ rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred,
                         *cred = NULL;
         int             nr = 0;
 
-        if (!(taskflags & RPC_TASK_ROOTCREDS))
+        if (!(flags & RPCAUTH_LOOKUP_ROOTCREDS))
                 nr = acred->uid & RPC_CREDCACHE_MASK;
 retry:
         spin_lock(&rpc_credcache_lock);
@@ -202,7 +202,7 @@ retry:
         hlist_for_each_safe(pos, next, &cache->hashtable[nr]) {
                 struct rpc_cred *entry;
                 entry = hlist_entry(pos, struct rpc_cred, cr_hash);
-                if (entry->cr_ops->crmatch(acred, entry, taskflags)) {
+                if (entry->cr_ops->crmatch(acred, entry, flags)) {
                         hlist_del(&entry->cr_hash);
                         cred = entry;
                         break;
@@ -224,7 +224,7 @@ retry:
         rpcauth_destroy_credlist(&free);
 
         if (!cred) {
-                new = auth->au_ops->crcreate(auth, acred, taskflags);
+                new = auth->au_ops->crcreate(auth, acred, flags);
                 if (!IS_ERR(new)) {
 #ifdef RPC_DEBUG
                         new->cr_magic = RPCAUTH_CRED_MAGIC;
@@ -238,7 +238,7 @@ retry:
 }
 
 struct rpc_cred *
-rpcauth_lookupcred(struct rpc_auth *auth, int taskflags)
+rpcauth_lookupcred(struct rpc_auth *auth, int flags)
 {
         struct auth_cred acred = {
                 .uid = current->fsuid,
@@ -250,7 +250,7 @@ rpcauth_lookupcred(struct rpc_auth *auth, int taskflags)
         dprintk("RPC:     looking up %s cred\n",
                 auth->au_ops->au_name);
         get_group_info(acred.group_info);
-        ret = auth->au_ops->lookup_cred(auth, &acred, taskflags);
+        ret = auth->au_ops->lookup_cred(auth, &acred, flags);
         put_group_info(acred.group_info);
         return ret;
 }
@@ -265,11 +265,14 @@ rpcauth_bindcred(struct rpc_task *task)
                 .group_info = current->group_info,
         };
         struct rpc_cred *ret;
+        int flags = 0;
 
         dprintk("RPC: %4d looking up %s cred\n",
                 task->tk_pid, task->tk_auth->au_ops->au_name);
         get_group_info(acred.group_info);
-        ret = auth->au_ops->lookup_cred(auth, &acred, task->tk_flags);
+        if (task->tk_flags & RPC_TASK_ROOTCREDS)
+                flags |= RPCAUTH_LOOKUP_ROOTCREDS;
+        ret = auth->au_ops->lookup_cred(auth, &acred, flags);
         if (!IS_ERR(ret))
                 task->tk_msg.rpc_cred = ret;
         else