switch mount_capable() to fs_context

	now both callers of mount_capable() have access to fs_context;
the only difference is that for sget_fc() we have the possibility
of fc->global being true, while for legacy_get_tree() it's guaranteed
to be impossible.  Unify to more generic variant...

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

1 files changed, 7 insertions, 4 deletions

diff --git a/fs/super.c b/fs/super.c
index bdb03255c7ea..d1e2f46bad7e 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -476,12 +476,15 @@ void generic_shutdown_super(struct super_block *sb)
 
 EXPORT_SYMBOL(generic_shutdown_super);
 
-bool mount_capable(struct file_system_type *type, struct user_namespace *userns)
+bool mount_capable(struct fs_context *fc)
 {
-        if (!(type->fs_flags & FS_USERNS_MOUNT))
+        struct user_namespace *user_ns = fc->global ? &init_user_ns
+                                                    : fc->user_ns;
+
+        if (!(fc->fs_type->fs_flags & FS_USERNS_MOUNT))
                 return capable(CAP_SYS_ADMIN);
         else
-                return ns_capable(userns, CAP_SYS_ADMIN);
+                return ns_capable(user_ns, CAP_SYS_ADMIN);
 }
 
 /**
@@ -513,7 +516,7 @@ struct super_block *sget_fc(struct fs_context *fc,
 
         if (!(fc->sb_flags & SB_KERNMOUNT) &&
             fc->purpose != FS_CONTEXT_FOR_SUBMOUNT) {
-                if (!mount_capable(fc->fs_type, user_ns))
+                if (!mount_capable(fc))
                         return ERR_PTR(-EPERM);
         }