bpf: Implement show_options

Implement the show_options superblock op for bpf as part of a bid to get
rid of s_options and generic_show_options() to make it easier to implement
a context-based mount where the mount options can be passed individually
over a file descriptor.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Alexei Starovoitov <ast@kernel.org>
cc: Daniel Borkmann <daniel@iogearbox.net>
cc: netdev@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 13 insertions, 3 deletions

diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c
index 9bbd33497d3d..e833ed914358 100644
--- a/kernel/bpf/inode.c
+++ b/kernel/bpf/inode.c
@@ -377,10 +377,22 @@ static void bpf_evict_inode(struct inode *inode)
                 bpf_any_put(inode->i_private, type);
 }
 
+/*
+ * Display the mount options in /proc/mounts.
+ */
+static int bpf_show_options(struct seq_file *m, struct dentry *root)
+{
+        umode_t mode = d_inode(root)->i_mode & S_IALLUGO & ~S_ISVTX;
+
+        if (mode != S_IRWXUGO)
+                seq_printf(m, ",mode=%o", mode);
+        return 0;
+}
+
 static const struct super_operations bpf_super_ops = {
         .statfs         = simple_statfs,
         .drop_inode     = generic_delete_inode,
-        .show_options   = generic_show_options,
+        .show_options   = bpf_show_options,
         .evict_inode    = bpf_evict_inode,
 };
 
@@ -434,8 +446,6 @@ static int bpf_fill_super(struct super_block *sb, void *data, int silent)
         struct inode *inode;
         int ret;
 
-        save_mount_options(sb, data);
-
         ret = bpf_parse_options(data, &opts);
         if (ret)
                 return ret;