linux-kernel - Re: [PATCH v2 01/11] mount_setattr.2: document glibc >= 2.36 syscall wrappers

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Message-ID: <aj6j7ue3eddbawshyelvsxli2nxs6fznzbfdsilvnjbgvxwc6k@ecgdixnxdmuk>
Date: Thu, 7 Aug 2025 12:39:19 +0200
From: Alejandro Colomar <alx@...nel.org>
To: Aleksa Sarai <cyphar@...har.com>
Cc: "Michael T. Kerrisk" <mtk.manpages@...il.com>, 
	Alexander Viro <viro@...iv.linux.org.uk>, Jan Kara <jack@...e.cz>, Askar Safin <safinaskar@...omail.com>, 
	"G. Branden Robinson" <g.branden.robinson@...il.com>, linux-man@...r.kernel.org, linux-api@...r.kernel.org, 
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, 
	David Howells <dhowells@...hat.com>, Christian Brauner <brauner@...nel.org>
Subject: Re: [PATCH v2 01/11] mount_setattr.2: document glibc >= 2.36 syscall
 wrappers

Hi Aleksa,

On Thu, Aug 07, 2025 at 03:44:35AM +1000, Aleksa Sarai wrote:
> Glibc 2.36 added syscall wrappers for the entire family of fd-based
> mount syscalls, including mount_setattr(2).  Thus it's no longer
> necessary to instruct users to do raw syscall(2) operations.
> 
> Signed-off-by: Aleksa Sarai <cyphar@...har.com>

Thanks!  I've applied and pushed the patch.


Have a lovely day!
Alex

> ---
>  man/man2/mount_setattr.2 | 45 +++++++--------------------------------------
>  1 file changed, 7 insertions(+), 38 deletions(-)
> 
> diff --git a/man/man2/mount_setattr.2 b/man/man2/mount_setattr.2
> index 60d9cf9de8aa..c96f0657f046 100644
> --- a/man/man2/mount_setattr.2
> +++ b/man/man2/mount_setattr.2
> @@ -10,21 +10,12 @@ .SH LIBRARY
>  .RI ( libc ,\~ \-lc )
>  .SH SYNOPSIS
>  .nf
> -.BR "#include <linux/fcntl.h>" " /* Definition of " AT_* " constants */"
> -.BR "#include <linux/mount.h>" " /* Definition of " MOUNT_ATTR_* " constants */"
> -.BR "#include <sys/syscall.h>" " /* Definition of " SYS_* " constants */"
> -.B #include <unistd.h>
> +.BR "#include <fcntl.h>" "       /* Definition of " AT_* " constants */"
> +.B #include <sys/mount.h>
>  .P
> -.BI "int syscall(SYS_mount_setattr, int " dirfd ", const char *" path ,
> -.BI "            unsigned int " flags ", struct mount_attr *" attr \
> -", size_t " size );
> +.BI "int mount_setattr(int " dirfd ", const char *" path ", unsigned int " flags ","
> +.BI "                  struct mount_attr *" attr ", size_t " size );"
>  .fi
> -.P
> -.IR Note :
> -glibc provides no wrapper for
> -.BR mount_setattr (),
> -necessitating the use of
> -.BR syscall (2).
>  .SH DESCRIPTION
>  The
>  .BR mount_setattr ()
> @@ -586,6 +577,7 @@ .SH HISTORY
>  .\" commit 7d6beb71da3cc033649d641e1e608713b8220290
>  .\" commit 2a1867219c7b27f928e2545782b86daaf9ad50bd
>  .\" commit 9caccd41541a6f7d6279928d9f971f6642c361af
> +glibc 2.36.
>  .SH NOTES
>  .SS ID-mapped mounts
>  Creating an ID-mapped mount makes it possible to
> @@ -914,37 +906,14 @@ .SH EXAMPLES
>  #include <err.h>
>  #include <fcntl.h>
>  #include <getopt.h>
> -#include <linux/mount.h>
> -#include <linux/types.h>
> +#include <sys/mount.h>
> +#include <sys/types.h>
>  #include <stdbool.h>
>  #include <stdio.h>
>  #include <stdlib.h>
>  #include <string.h>
> -#include <sys/syscall.h>
>  #include <unistd.h>
>  \&
> -static inline int
> -mount_setattr(int dirfd, const char *path, unsigned int flags,
> -              struct mount_attr *attr, size_t size)
> -{
> -    return syscall(SYS_mount_setattr, dirfd, path, flags,
> -                   attr, size);
> -}
> -\&
> -static inline int
> -open_tree(int dirfd, const char *filename, unsigned int flags)
> -{
> -    return syscall(SYS_open_tree, dirfd, filename, flags);
> -}
> -\&
> -static inline int
> -move_mount(int from_dirfd, const char *from_path,
> -           int to_dirfd, const char *to_path, unsigned int flags)
> -{
> -    return syscall(SYS_move_mount, from_dirfd, from_path,
> -                   to_dirfd, to_path, flags);
> -}
> -\&
>  static const struct option longopts[] = {
>      {"map\-mount",       required_argument,  NULL,  \[aq]a\[aq]},
>      {"recursive",       no_argument,        NULL,  \[aq]b\[aq]},
> 
> -- 
> 2.50.1
> 
> 

-- 
<https://www.alejandro-colomar.es/>

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