linux-kernel - Re: [PATCH v2] docs: Remove outdated highuid.rst documentation

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Message-ID: <87h63re0nv.fsf@trenco.lwn.net>
Date: Mon, 17 Mar 2025 16:45:56 -0600
From: Jonathan Corbet <corbet@....net>
To: kth <kangtaeho2456@...il.com>
Cc: willy@...radead.org, linux-doc@...r.kernel.org,
 linux-kernel@...r.kernel.org, kth <kangtaeho2456@...il.com>
Subject: Re: [PATCH v2] docs: Remove outdated highuid.rst documentation

kth <kangtaeho2456@...il.com> writes:

> The highuid.rst document describes a transition that is outdated and no
> longer relevant. Additionally, it references filesystems (ncpfs and smbfs),
> which have been removed or replaced.
>
> Suggested-by: Matthew Wilcox <willy@...radead.org>
> Signed-off-by: Kang Taeho <kangtaeho2456@...il.com>
> ---
>  Documentation/admin-guide/highuid.rst | 80 ---------------------------
>  Documentation/admin-guide/index.rst   |  1 -
>  2 files changed, 81 deletions(-)
>  delete mode 100644 Documentation/admin-guide/highuid.rst

OK, I have applied this, but it was some work.  For future reference:

- When you do a v2 (or whatever), always include a description of what
  changed since the previous version under the "---" line.

- Before sending another patch, email it to yourself and be sure that
  you can apply what you receive.  This patch was whitespace damaged,
  but that is not all ...

>
> diff --git a/Documentation/admin-guide/highuid.rst b/Documentation/admin-guide/highuid.rst
> deleted file mode 100644
> index 9239067563a1..000000000000
> --- a/Documentation/admin-guide/highuid.rst
> +++ /dev/null
> @@ -1,80 +0,0 @@
> -===================================================
> -Notes on the change from 16-bit UIDs to 32-bit UIDs
> -===================================================
> -
> -:Author: Chris Wing <wingc@...ch.edu>
> -:Last updated: January 11, 2000
> -
> -- kernel code MUST take into account __kernel_uid_t and __kernel_uid32_t
> -  when communicating between user and kernel space in an ioctl or data
> -  structure.
> -
> -- kernel code should use uid_t and gid_t in kernel-private structures and
> -  code.
> -
> -What's left to be done for 32-bit UIDs on all Linux architectures:
> -
> -- Disk quotas have an interesting limitation that is not related to the
> -  maximum UID/GID. They are limited by the maximum file size on the
> -  underlying filesystem, because quota records are written at offsets
> -  corresponding to the UID in question.
> -  Further investigation is needed to see if the quota system can cope
> -  properly with huge UIDs. If it can deal with 64-bit file offsets on all 
> -  architectures, this should not be a problem.
> -
> -- Decide whether or not to keep backwards compatibility with the system
> -  accounting file, or if we should break it as the comments suggest
> -  (currently, the old 16-bit UID and GID are still written to disk, and
> -  part of the former pad space is used to store separate 32-bit UID and
> -  GID)
> -
> -- Need to validate that OS emulation calls the 16-bit UID
> -  compatibility syscalls, if the OS being emulated used 16-bit UIDs, or
> -  uses the 32-bit UID system calls properly otherwise.
> -
> -  This affects at least:
> -
> -	- iBCS on Intel
> -
> -	- sparc32 emulation on sparc64
> -	  (need to support whatever new 32-bit UID system calls are added to
> -	  sparc32)
> -
> -- Validate that all filesystems behave properly.
> -
> -  At present, 32-bit UIDs _should_ work for:
> -
> -	- ext2
> -	- ufs
> -	- isofs
> -	- nfs
> -	- coda
> -	- udf
> -
> -  Ioctl() fixups have been made for:
> -
> -	- ncpfs
> -	- smbfs
> -
> -  Filesystems with simple fixups to prevent 16-bit UID wraparound:
> -
> -	- minix
> -	- sysv
> -	- qnx4
> -
> -  Other filesystems have not been checked yet.
> -
> -- The ncpfs and smbfs filesystems cannot presently use 32-bit UIDs in

This line here     ^^^^^   contains your previous attempted fix; that,
too, caused the patch to fail to apply.  I had to hand edit it to get
past that.

Thanks,

jon