fix NFS4 handling of mountpoint stat

RFC says we need to follow the chain of mounts if there's more
than one stacked on that point.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index a8587e90fd5a837bfce993d9cebaeb9f1697f825..bbf72d8f9fc0a36bf10ef7a2c509e9f3239ea06e 100644 (file)
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2121,9 +2121,15 @@ out_acl:
                 * and this is the root of a cross-mounted filesystem.
                 */
                if (ignore_crossmnt == 0 &&
-                   exp->ex_path.mnt->mnt_root->d_inode == dentry->d_inode) {
-                       err = vfs_getattr(exp->ex_path.mnt->mnt_parent,
-                               exp->ex_path.mnt->mnt_mountpoint, &stat);
+                   dentry == exp->ex_path.mnt->mnt_root) {
+                       struct path path = exp->ex_path;
+                       path_get(&path);
+                       while (follow_up(&path)) {
+                               if (path.dentry != path.mnt->mnt_root)
+                                       break;
+                       }
+                       err = vfs_getattr(path.mnt, path.dentry, &stat);
+                       path_put(&path);
                        if (err)
                                goto out_nfserr;
                }