NFS: Ensure the client submounts, when it crosses a server mountpoint.

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

1 files changed, 16 insertions, 0 deletions

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 1d3d8922a663..3ddda6f7ecc2 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -868,6 +868,17 @@ int nfs_is_exclusive_create(struct inode *dir, struct nameidata *nd)
         return (nd->intent.open.flags & O_EXCL) != 0;
 }
 
+static inline int nfs_reval_fsid(struct inode *dir,
+                struct nfs_fh *fh, struct nfs_fattr *fattr)
+{
+        struct nfs_server *server = NFS_SERVER(dir);
+
+        if (!nfs_fsid_equal(&server->fsid, &fattr->fsid))
+                /* Revalidate fsid on root dir */
+                return __nfs_revalidate_inode(server, dir->i_sb->s_root->d_inode);
+        return 0;
+}
+
 static struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *nd)
 {
         struct dentry *res;
@@ -900,6 +911,11 @@ static struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry, stru
                 res = ERR_PTR(error);
                 goto out_unlock;
         }
+        error = nfs_reval_fsid(dir, &fhandle, &fattr);
+        if (error < 0) {
+                res = ERR_PTR(error);
+                goto out_unlock;
+        }
         inode = nfs_fhget(dentry->d_sb, &fhandle, &fattr);
         res = (struct dentry *)inode;
         if (IS_ERR(res))