if (readonly_request == __mnt_is_readonly(mnt))
return 0;
- if (mnt->mnt_flags & MNT_LOCK_READONLY)
- return -EPERM;
-
if (readonly_request)
error = mnt_make_readonly(real_mount(mnt));
else
if (path->dentry != path->mnt->mnt_root)
return -EINVAL;
+ /* Don't allow changing of locked mnt flags.
+ *
+ * No locks need to be held here while testing the various
+ * MNT_LOCK flags because those flags can never be cleared
+ * once they are set.
+ */
+ if ((mnt->mnt.mnt_flags & MNT_LOCK_READONLY) &&
+ !(mnt_flags & MNT_READONLY)) {
+ return -EPERM;
+ }
err = security_sb_remount(sb, data);
if (err)
return err;