NFSv4: Make the NFS state model work with the nosharedcache mount option

Consider the case where the user has mounted the remote filesystem
server:/foo on the two local directories /bar and /baz using the
nosharedcache mount option. The files /bar/file and /baz/file are
represented by different inodes in the local namespace, but refer to the
same file /foo/file on the server.
Consider the case where a process opens both /bar/file and /baz/file, then
closes /bar/file: because the nfs4_state is not shared between /bar/file
and /baz/file, the kernel will see that the nfs4_state for /bar/file is no
longer referenced, so it will send off a CLOSE rpc call. Unless the
open_owners differ, then that CLOSE call will invalidate the open state on
/baz/file too.

Conclusion: we cannot share open state owners between two different
non-shared mount instances of the same filesystem.

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

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index dd1aa2b598ce..6c028e734fe6 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -83,6 +83,7 @@ struct nfs_unique_id {
 struct nfs4_state_owner {
         struct nfs_unique_id so_owner_id;
         struct nfs_client    *so_client;
+        struct nfs_server    *so_server;
         struct rb_node       so_client_node;
 
         struct rpc_cred      *so_cred;   /* Associated cred */