On Tue, May 05, 2020 at 11:59:04AM +0200, Miklos Szeredi wrote:
> Whiteouts, unlike real device node should not require privileges to create.
>
> The general concern with device nodes is that opening them can have side
> effects. The kernel already avoids zero major (see
> Documentation/admin-guide/devices.txt). To be on the safe side the patch
> explicitly forbids registering a char device with 0/0 number (see
> cdev_add()).
>
> This guarantees that a non-O_PATH open on a whiteout will fail with ENODEV;
> i.e. it won't have any side effect.
Humm... one question:
> int vfs_whiteout(struct inode *dir, struct dentry *dentry)
> {
> - int error = may_create(dir, dentry);
> - if (error)
> - return error;
> -
> - if (!dir->i_op->mknod)
> - return -EPERM;
> -
> - return dir->i_op->mknod(dir, dentry,
> - S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
> + return vfs_mknod(dir, dentry, S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
> }
why do we still need to export it? I mean, it looks like
a static inline fodder.
