e6c9a71451
Add simple helpers to make it easy to map kuids into and from idmapped
mounts. We provide simple wrappers that filesystems can use to e.g.
initialize inodes similar to i_{uid,gid}_read() and i_{uid,gid}_write().
Accessing an inode through an idmapped mount maps the i_uid and i_gid of
the inode to the mount's user namespace. If the fsids are used to
initialize inodes they are unmapped according to the mount's user
namespace. Passing the initial user namespace to these helpers makes
them a nop and so any non-idmapped paths will not be impacted.
Link: https://lore.kernel.org/r/20210121131959.646623-3-christian.brauner@ubuntu.com
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.