NFSv4: Remove BUG_ON() and ACCESS_ONCE() calls in the idmapper

The use of ACCESS_ONCE() is wrong, since the various routines that set/clear
idmap->idmap_key_cons should be strictly ordered w.r.t. each other, and
the idmap->idmap_mutex ensures that only one thread at a time may be in
an upcall situation.

Also replace the BUG_ON()s with WARN_ON_ONCE() where appropriate.

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

diff --git a/fs/nfs/idmap.c b/fs/nfs/idmap.c
index a850079467d85f149d997b9c96176c9a0829be0d..79f6424aa0819b7a56d0835d1d2418c9ea703b4d 100644 (file)
--- a/fs/nfs/idmap.c
+++ b/fs/nfs/idmap.c
@@ -465,8 +465,6 @@ nfs_idmap_new(struct nfs_client *clp)
        struct rpc_pipe *pipe;
        int error;
 
-       BUG_ON(clp->cl_idmap != NULL);
-
        idmap = kzalloc(sizeof(*idmap), GFP_KERNEL);
        if (idmap == NULL)
                return -ENOMEM;
@@ -510,7 +508,6 @@ static int __rpc_pipefs_event(struct nfs_client *clp, unsigned long event,
 
        switch (event) {
        case RPC_PIPEFS_MOUNT:
-               BUG_ON(clp->cl_rpcclient->cl_dentry == NULL);
                err = __nfs_idmap_register(clp->cl_rpcclient->cl_dentry,
                                                clp->cl_idmap,
                                                clp->cl_idmap->idmap_pipe);
@@ -689,7 +686,11 @@ static int nfs_idmap_legacy_upcall(struct key_construction *cons,
        if (ret < 0)
                goto out2;
 
-       BUG_ON(idmap->idmap_key_cons != NULL);
+       if (idmap->idmap_key_cons != NULL) {
+               WARN_ON_ONCE(1);
+               ret = -EAGAIN;
+               goto out2;
+       }
        idmap->idmap_key_cons = cons;
 
        ret = rpc_queue_upcall(idmap->idmap_pipe, msg);
@@ -746,7 +747,7 @@ idmap_pipe_downcall(struct file *filp, const char __user *src, size_t mlen)
         * 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 = ACCESS_ONCE(idmap->idmap_key_cons);
+       cons = idmap->idmap_key_cons;
        idmap->idmap_key_cons = NULL;
 
        if (mlen != sizeof(im)) {
@@ -790,7 +791,7 @@ idmap_pipe_destroy_msg(struct rpc_pipe_msg *msg)
        struct idmap *idmap = data->idmap;
        struct key_construction *cons;
        if (msg->errno) {
-               cons = ACCESS_ONCE(idmap->idmap_key_cons);
+               cons = idmap->idmap_key_cons;
                idmap->idmap_key_cons = NULL;
                complete_request_key(cons, msg->errno);
        }