Re: [PATCH] erofs: use the opener's credential when verifing metadata accesses

[Christoph Hellwig]

On Tue, May 05, 2026 at 11:56:15PM +0800, Gao Xiang wrote:
> Similar to commit 905eeb2b7c33 ("erofs: impersonate the opener's
> credentials when accessing backing file"), rw_verify_area() needs
> the same too.

Two things here:

 - rw_verify_area is a helper for use inside the VFS and file system
   read/write method implementation.  Erofs as a user of the VFS should
   not use it at all.
 - using the opener credentials when accessing the backing file seems
   wrong.  The entity accessing it is the file system, so it should
   have system or mounter credentials, not that of someone causing
   metadata / fs data access.  And this applies to all access by
   a file system backed by a backing file.