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45c311501c
Add ia_vfs{g,u}id members of type vfs{g,u}id_t to struct iattr. We use
an anonymous union (similar to what we do in struct file) around
ia_{g,u}id and ia_vfs{g,u}id.
At the end of this series ia_{g,u}id and ia_vfs{g,u}id will always
contain the same value independent of whether struct iattr is
initialized from an idmapped mount. This is a change from how this is
done today.
Wrapping this in a anonymous unions has a few advantages. It allows us
to avoid needlessly increasing struct iattr. Since the types for
ia_{g,u}id and ia_vfs{g,u}id are structures with overlapping/identical
members they are covered by 6.5.2.3/6 of the C standard and it is safe
to initialize and access them.
Filesystems that raise FS_ALLOW_IDMAP and thus support idmapped mounts
will have to use ia_vfs{g,u}id and the associated helpers. And will be
ported at the end of this series. They will immediately benefit from the
type safe new helpers.
Filesystems that do not support FS_ALLOW_IDMAP can continue to use
ia_{g,u}id for now. The aim is to convert every filesystem to always use
ia_vfs{g,u}id and thus ultimately remove the ia_{g,u}id members.
Link: https://lore.kernel.org/r/20220621141454.2914719-4-brauner@kernel.org
Cc: Seth Forshee <sforshee@digitalocean.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
CC: linux-fsdevel@vger.kernel.org
Reviewed-by: Seth Forshee <sforshee@digitalocean.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
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.