NFSv4: Clean up the legacy idmapper upcall

Replace the BUG_ON(idmap->idmap_key_cons != NULL) with a
WARN_ON_ONCE(). Then get rid of the ACCESS_ONCE(idmap->idmap_key_cons).

Then add helper functions for starting, finishing and aborting the
legacy upcall.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Bryan Schumaker <bjschuma@netapp.com>

1 files changed, 44 insertions, 21 deletions

diff --git a/fs/nfs/idmap.c b/fs/nfs/idmap.c
index 79f6424aa081..8222ad861456 100644
--- a/fs/nfs/idmap.c
+++ b/fs/nfs/idmap.c
@@ -330,7 +330,6 @@ static ssize_t nfs_idmap_get_key(const char *name, size_t namelen,
                 ret = nfs_idmap_request_key(&key_type_id_resolver_legacy,
                                             name, namelen, type, data,
                                             data_size, idmap);
-                idmap->idmap_key_cons = NULL;
                 mutex_unlock(&idmap->idmap_mutex);
         }
         return ret;
@@ -662,6 +661,34 @@ out:
         return ret;
 }
 
+static bool
+nfs_idmap_prepare_pipe_upcall(struct idmap *idmap,
+                struct key_construction *cons)
+{
+        if (idmap->idmap_key_cons != NULL) {
+                WARN_ON_ONCE(1);
+                return false;
+        }
+        idmap->idmap_key_cons = cons;
+        return true;
+}
+
+static void
+nfs_idmap_complete_pipe_upcall_locked(struct idmap *idmap, int ret)
+{
+        struct key_construction *cons = idmap->idmap_key_cons;
+
+        idmap->idmap_key_cons = NULL;
+        complete_request_key(cons, ret);
+}
+
+static void
+nfs_idmap_abort_pipe_upcall(struct idmap *idmap, int ret)
+{
+        if (idmap->idmap_key_cons != NULL)
+                nfs_idmap_complete_pipe_upcall_locked(idmap, ret);
+}
+
 static int nfs_idmap_legacy_upcall(struct key_construction *cons,
                                    const char *op,
                                    void *aux)
@@ -686,21 +713,17 @@ static int nfs_idmap_legacy_upcall(struct key_construction *cons,
         if (ret < 0)
                 goto out2;
 
-        if (idmap->idmap_key_cons != NULL) {
-                WARN_ON_ONCE(1);
-                ret = -EAGAIN;
+        ret = -EAGAIN;
+        if (!nfs_idmap_prepare_pipe_upcall(idmap, cons))
                 goto out2;
-        }
-        idmap->idmap_key_cons = cons;
 
         ret = rpc_queue_upcall(idmap->idmap_pipe, msg);
-        if (ret < 0)
-                goto out3;
+        if (ret < 0) {
+                nfs_idmap_abort_pipe_upcall(idmap, ret);
+                kfree(data);
+        }
 
         return ret;
-
-out3:
-        idmap->idmap_key_cons = NULL;
 out2:
         kfree(data);
 out1:
@@ -741,14 +764,15 @@ idmap_pipe_downcall(struct file *filp, const char __user *src, size_t mlen)
         struct key_construction *cons;
         struct idmap_msg im;
         size_t namelen_in;
-        int ret;
+        int ret = -ENOKEY;
 
         /* If instantiation is successful, anyone waiting for key construction
          * will have been woken up and someone else may now have used
          * idmap_key_cons - so after this point we may no longer touch it.
          */
         cons = idmap->idmap_key_cons;
-        idmap->idmap_key_cons = NULL;
+        if (cons == NULL)
+                goto out_noupcall;
 
         if (mlen != sizeof(im)) {
                 ret = -ENOSPC;
@@ -778,7 +802,8 @@ idmap_pipe_downcall(struct file *filp, const char __user *src, size_t mlen)
         }
 
 out:
-        complete_request_key(cons, ret);
+        nfs_idmap_complete_pipe_upcall_locked(idmap, ret);
+out_noupcall:
         return ret;
 }
 
@@ -789,12 +814,9 @@ idmap_pipe_destroy_msg(struct rpc_pipe_msg *msg)
                         struct idmap_legacy_upcalldata,
                         pipe_msg);
         struct idmap *idmap = data->idmap;
-        struct key_construction *cons;
-        if (msg->errno) {
-                cons = idmap->idmap_key_cons;
-                idmap->idmap_key_cons = NULL;
-                complete_request_key(cons, msg->errno);
-        }
+
+        if (msg->errno)
+                nfs_idmap_abort_pipe_upcall(idmap, msg->errno);
         /* Free memory allocated in nfs_idmap_legacy_upcall() */
         kfree(data);
 }
@@ -804,7 +826,8 @@ idmap_release_pipe(struct inode *inode)
 {
         struct rpc_inode *rpci = RPC_I(inode);
         struct idmap *idmap = (struct idmap *)rpci->private;
-        idmap->idmap_key_cons = NULL;
+
+        nfs_idmap_abort_pipe_upcall(idmap, -EPIPE);
 }
 
 int nfs_map_name_to_uid(const struct nfs_server *server, const char *name, size_t namelen, __u32 *uid)