Re: [PATCH v2 1/4] man/man2/statmount.2: Document STATMOUNT_{UIDMAP,GIDMAP}

Alejandro Colomar <[email protected]> Mon, 23 Feb 2026 16:41:02 +0100
Newsgroups	dev.linux.lists.criu,org.kernel.vger.linux-man
Message-ID	<aZx02VGlW2GfBdce@devuan>
Hi Bhavik,

On 2026-02-23T19:40:23+0530, Bhavik Sachdev wrote:
> Document the STATMOUNT_{UIDMAP,GIDMAP} flags and the corresponding
> fields introduced by them. Most of this is based on the commit message
> provided here [1].
> 
> Link [1]:
> <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=37c4a9590e1efcae7749682239fc22a330d2d325>
> 
> Signed-off-by: Bhavik Sachdev <[email protected]>
> Message-ID: <6146fa1d59006387ad7996f28f5651787125d956.1771855135.git.b.sachdev1904@gmail.com>
> ---
> Hey Alex!
> 
> Hopefully this is what you wanted!

Yup, that was it.  :)

I've applied patches v2 1..3.  I've done some minor amends, and patch 4
doesn't apply.  Would you mind rebasing that one?


Have a lovely day!
Alex

> 
> Thanks,
> Bhavik
> 
>  man/man2/statmount.2 | 38 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 38 insertions(+)
> 
> diff --git a/man/man2/statmount.2 b/man/man2/statmount.2
> index f8d2302ef..f5a3721eb 100644
> --- a/man/man2/statmount.2
> +++ b/man/man2/statmount.2
> @@ -56,6 +56,10 @@ .SH SYNOPSIS
>  .B "    __u32  opt_array;"
>  .B "    __u32  opt_sec_num;"
>  .B "    __u32  opt_sec_array;"
> +.B "    __u32  mnt_uidmap_num;"
> +.B "    __u32  mnt_uidmap;"
> +.B "    __u32  mnt_gidmap_num;"
> +.B "    __u32  mnt_gidmap;"
>  .B "    char   str[];"
>  .B };
>  .EE
> @@ -120,6 +124,8 @@ .SS The mnt_id_req structure
>  STATMOUNT_SB_SOURCE	/* Want/got sb_source */
>  STATMOUNT_OPT_ARRAY	/* Want/got opt_{num,array} */
>  STATMOUNT_OPT_SEC_ARRAY	/* Want/got opt_sec_{num,array} */
> +STATMOUNT_MNT_UIDMAP	/* Want/got uidmap... */
> +STATMOUNT_MNT_GIDMAP	/* Want/got gidmap... */
>  .TE
>  .in
>  .P
> @@ -302,6 +308,38 @@ .SS The returned information
>  buffer that contains security options separated by null bytes.
>  They can be iterated over with the help of
>  .IR smbuf.opt_sec_num .
> +.TP
> +.IR smbuf.mnt_uidmap_num " (since Linux 6.15)"
> +The number of uid mappings applied on the mount.
> +If
> +.I smbuf.mask
> +has STATMOUNT_UIDMAP set and this field is 0,
> +the mount is not an idmapped mount.
> +.TP
> +.IR smbuf.mnt_uidmap " (since Linux 6.15)"
> +The offset to the location in the
> +.I smbuf.str
> +buffer that contains uid mappings as consecutive null-terminated strings.
> +They can be iterated over with the help of
> +.IR smbuf.mnt_uidmap_num .
> +The whole range of uid mappings must be resolvable in the user namespace
> +of the caller.
> +.TP
> +.IR smbuf.mnt_gidmap_num " (since Linux 6.15)"
> +The number of gid mappings applied on the mount.
> +If
> +.I smbuf.mask
> +has STATMOUNT_GIDMAP set and this field is 0,
> +the mount is not an idmapped mount.
> +.TP
> +.IR smbuf.mnt_gidmap " (since Linux 6.15)"
> +The offset to the location in the
> +.I smbuf.str
> +buffer that contains gid mappings as consecutive null-terminated strings.
> +They can be iterated over with the help of
> +.IR smbuf.mnt_gidmap_num .
> +The whole range of gid mappings must be resolvable in the user namespace
> +of the caller.
>  .SH RETURN VALUE
>  On success, zero is returned.
>  On error, \-1 is returned, and
> -- 
> 2.53.0
> 

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