[PATCH] shmem: support xattr gnu.* namespace for the Hurd

[PATCH] shmem: support xattr gnu.* namespace for the Hurd

[Janneke Nieuwenhuizen]

The Hurd gained[0] support for moving the translator and author
fields out of the inode and into the "gnu.*" xattr namespace.

In anticipation of that, an xattr INDEX was reserved[1].  In 2020, the
Hurd has been brought into compliance[2] with that, and so has ext4[3].

This patch adds support for reading and writing such attributes from
a Linux tmpfs; you can now do something like

    mkdir -p hurd-root
    mount -t tmpfs -o size=2M tmpfs hurd-root
    mkdir -p hurd-root/servers/socket
    touch hurd-root/servers/socket/1
    setfattr --name=gnu.translator --value='"/hurd/pflocal\0"' \
        hurd-root/servers/socket/1
    getfattr --name=gnu.translator hurd-root/servers/socket/1
    # file: 1
    gnu.translator="/hurd/pflocal"

to setup a pipe translator, which is being used to create an initial
file-system image for the Hurd from GNU Guix[4].

[0] https://summerofcode.withgoogle.com/projects/#5869799859027968
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3980bd3b406addb327d858aebd19e229ea340b9a
[2] https://git.savannah.gnu.org/cgit/hurd/hurd.git/commit/?id=a04c7bf83172faa7cb080fbe3b6c04a8415ca645
[3] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=88ee9d571b6d8ed345f877e05f685814412e359b
[4] https://codeberg.org/guix/guix/pulls/8632
---
 mm/shmem.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/mm/shmem.c b/mm/shmem.c
index 3b5dc21b323c..5d60aa4dba92 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -15,6 +15,7 @@
  * Extended attribute support for tmpfs:
  * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
  * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
+ * Copyright (C) 2026 Janneke Nieuwenhuizen <janneke@gnu.org>
  *
  * tiny-shmem:
  * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
@@ -4371,10 +4372,17 @@ static const struct xattr_handler shmem_user_xattr_handler = {
 	.set = shmem_xattr_handler_set,
 };
 
+static const struct xattr_handler shmem_hurd_xattr_handler = {
+	.prefix = XATTR_HURD_PREFIX,
+	.get = shmem_xattr_handler_get,
+	.set = shmem_xattr_handler_set,
+};
+
 static const struct xattr_handler * const shmem_xattr_handlers[] = {
 	&shmem_security_xattr_handler,
 	&shmem_trusted_xattr_handler,
 	&shmem_user_xattr_handler,
+	&shmem_hurd_xattr_handler,
 	NULL
 };
 
-- 
2.54.0


-- 
Reasonable | Free Software for Correctness | GNU Dezyne -- https://dezyne.org
+Sourcery+ | Correctness for Free Software | https://reasonable-sourcery.coop

[PATCH] shmem: support xattr gnu.* namespace for the Hurd

[Janneke Nieuwenhuizen]

From d8291d06b67db045033664fb440f59001d7755a1 Mon Sep 17 00:00:00 2001
From: Janneke Nieuwenhuizen <janneke@gnu.org>
Date: Fri, 15 May 2026 10:12:30 +0200
Subject: [PATCH] shmem: support xattr gnu.* namespace for the Hurd

The Hurd gained[0] support for moving the translator and author
fields out of the inode and into the "gnu.*" xattr namespace.

In anticipation of that, an xattr INDEX was reserved[1].  The Hurd has
now been brought into compliance[2] with that, and so has ext4[3].

This patch adds support for reading and writing such attributes from
a Linux tmpfs; you can now do something like

    mkdir -p hurd-root
    mount -t tmpfs -o size=2M tmpfs hurd-root
    mkdir -p hurd-root/servers/socket
    touch hurd-root/servers/socket/1
    setfattr --name=gnu.translator --value='"/hurd/pflocal\0"' \
        hurd-root/servers/socket/1
    getfattr --name=gnu.translator hurd-root/servers/socket/1
    # file: 1
    gnu.translator="/hurd/pflocal"

to setup a pipe translator, which is being used to create an
initial file-system image for the Hurd from GNU Guix[4].

[0] https://summerofcode.withgoogle.com/projects/#5869799859027968
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3980bd3b406addb327d858aebd19e229ea340b9a
[2] https://git.savannah.gnu.org/cgit/hurd/hurd.git/commit/?id=a04c7bf83172faa7cb080fbe3b6c04a8415ca645
[3] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=88ee9d571b6d8ed345f877e05f685814412e359b
[4] https://codeberg.org/guix/guix/pulls/8632
---
 mm/shmem.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/mm/shmem.c b/mm/shmem.c
index 3b5dc21b323c..5d60aa4dba92 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -15,6 +15,7 @@
  * Extended attribute support for tmpfs:
  * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
  * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
+ * Copyright (C) 2026 Janneke Nieuwenhuizen <janneke@gnu.org>
  *
  * tiny-shmem:
  * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
@@ -4371,10 +4372,17 @@ static const struct xattr_handler shmem_user_xattr_handler = {
 	.set = shmem_xattr_handler_set,
 };
 
+static const struct xattr_handler shmem_hurd_xattr_handler = {
+	.prefix = XATTR_HURD_PREFIX,
+	.get = shmem_xattr_handler_get,
+	.set = shmem_xattr_handler_set,
+};
+
 static const struct xattr_handler * const shmem_xattr_handlers[] = {
 	&shmem_security_xattr_handler,
 	&shmem_trusted_xattr_handler,
 	&shmem_user_xattr_handler,
+	&shmem_hurd_xattr_handler,
 	NULL
 };
 
-- 
2.54.0


-- 
Reasonable | Free Software for Correctness | GNU Dezyne -- https://dezyne.org
+Sourcery+ | Correctness for Free Software | https://reasonable-sourcery.coop

Re: [PATCH] shmem: support xattr gnu.* namespace for the Hurd

[Baolin Wang]

CC fs maillist

On 5/16/26 3:58 AM, Janneke Nieuwenhuizen wrote:
>  From d8291d06b67db045033664fb440f59001d7755a1 Mon Sep 17 00:00:00 2001
> From: Janneke Nieuwenhuizen <janneke@gnu.org>
> Date: Fri, 15 May 2026 10:12:30 +0200
> Subject: [PATCH] shmem: support xattr gnu.* namespace for the Hurd
> 
> The Hurd gained[0] support for moving the translator and author
> fields out of the inode and into the "gnu.*" xattr namespace.
> 
> In anticipation of that, an xattr INDEX was reserved[1].  The Hurd has
> now been brought into compliance[2] with that, and so has ext4[3].
> 
> This patch adds support for reading and writing such attributes from
> a Linux tmpfs; you can now do something like
> 
>      mkdir -p hurd-root
>      mount -t tmpfs -o size=2M tmpfs hurd-root
>      mkdir -p hurd-root/servers/socket
>      touch hurd-root/servers/socket/1
>      setfattr --name=gnu.translator --value='"/hurd/pflocal\0"' \
>          hurd-root/servers/socket/1
>      getfattr --name=gnu.translator hurd-root/servers/socket/1
>      # file: 1
>      gnu.translator="/hurd/pflocal"
> 
> to setup a pipe translator, which is being used to create an
> initial file-system image for the Hurd from GNU Guix[4].

Please add your Singed-off-by tag.

> [0] https://summerofcode.withgoogle.com/projects/#5869799859027968
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3980bd3b406addb327d858aebd19e229ea340b9a
> [2] https://git.savannah.gnu.org/cgit/hurd/hurd.git/commit/?id=a04c7bf83172faa7cb080fbe3b6c04a8415ca645
> [3] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=88ee9d571b6d8ed345f877e05f685814412e359b
> [4] https://codeberg.org/guix/guix/pulls/8632
> ---
>   mm/shmem.c | 8 ++++++++
>   1 file changed, 8 insertions(+)
> 
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 3b5dc21b323c..5d60aa4dba92 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -15,6 +15,7 @@
>    * Extended attribute support for tmpfs:
>    * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
>    * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
> + * Copyright (C) 2026 Janneke Nieuwenhuizen <janneke@gnu.org>
>    *
>    * tiny-shmem:
>    * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
> @@ -4371,10 +4372,17 @@ static const struct xattr_handler shmem_user_xattr_handler = {
>   	.set = shmem_xattr_handler_set,
>   };
>   
> +static const struct xattr_handler shmem_hurd_xattr_handler = {
> +	.prefix = XATTR_HURD_PREFIX,
> +	.get = shmem_xattr_handler_get,
> +	.set = shmem_xattr_handler_set,
> +};
> +
>   static const struct xattr_handler * const shmem_xattr_handlers[] = {
>   	&shmem_security_xattr_handler,
>   	&shmem_trusted_xattr_handler,
>   	&shmem_user_xattr_handler,
> +	&shmem_hurd_xattr_handler,
>   	NULL
>   };
>   

Re: [PATCH] shmem: support xattr gnu.* namespace for the Hurd

[Janneke Nieuwenhuizen]

[-- Attachment #1: Type: text/plain, Size: 544 bytes --]

Baolin Wang writes:

Hi Baolin,

> On 5/16/26 3:58 AM, Janneke Nieuwenhuizen wrote:
>>  From d8291d06b67db045033664fb440f59001d7755a1 Mon Sep 17 00:00:00 2001
>> From: Janneke Nieuwenhuizen <janneke@gnu.org>
>> Date: Fri, 15 May 2026 10:12:30 +0200
>> Subject: [PATCH] shmem: support xattr gnu.* namespace for the Hurd
[..]
>> to setup a pipe translator, which is being used to create an
>> initial file-system image for the Hurd from GNU Guix[4].
>
> Please add your Singed-off-by tag.

Done; find a new version attached.

Greetings,
Janneke


[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: 0001-shmem-support-xattr-gnu.-namespace-for-the-Hurd.patch --]
[-- Type: text/x-patch, Size: 2630 bytes --]

From 4ff8927bb044dab11fca9b258e7b9c0b221ac912 Mon Sep 17 00:00:00 2001
From: Janneke Nieuwenhuizen <janneke@gnu.org>
Date: Fri, 15 May 2026 10:12:30 +0200
Subject: [PATCH] shmem: support xattr gnu.* namespace for the Hurd

The Hurd gained[0] support for moving the translator and author
fields out of the inode and into the "gnu.*" xattr namespace.

In anticipation of that, an xattr INDEX was reserved[1].  The Hurd has
now been brought into compliance[2] with that, and so has ext4[3].

This patch adds support for reading and writing such attributes from
a Linux tmpfs; you can now do something like

    mkdir -p hurd-root
    mount -t tmpfs -o size=2M tmpfs hurd-root
    mkdir -p hurd-root/servers/socket
    touch hurd-root/servers/socket/1
    setfattr --name=gnu.translator --value='"/hurd/pflocal\0"' \
        hurd-root/servers/socket/1
    getfattr --name=gnu.translator hurd-root/servers/socket/1
    # file: 1
    gnu.translator="/hurd/pflocal"

to setup a pipe translator, which is being used to create an
initial file-system image for the Hurd from GNU Guix[4].

[0] https://summerofcode.withgoogle.com/projects/#5869799859027968
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3980bd3b406addb327d858aebd19e229ea340b9a
[2] https://git.savannah.gnu.org/cgit/hurd/hurd.git/commit/?id=a04c7bf83172faa7cb080fbe3b6c04a8415ca645
[3] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=88ee9d571b6d8ed345f877e05f685814412e359b
[4] https://codeberg.org/guix/guix/pulls/8632

Signed-off-by: Janneke Nieuwenhuizen <janneke@gnu.org>
---
 mm/shmem.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/mm/shmem.c b/mm/shmem.c
index 3b5dc21b323c..5d60aa4dba92 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -15,6 +15,7 @@
  * Extended attribute support for tmpfs:
  * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
  * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
+ * Copyright (C) 2026 Janneke Nieuwenhuizen <janneke@gnu.org>
  *
  * tiny-shmem:
  * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
@@ -4371,10 +4372,17 @@ static const struct xattr_handler shmem_user_xattr_handler = {
 	.set = shmem_xattr_handler_set,
 };
 
+static const struct xattr_handler shmem_hurd_xattr_handler = {
+	.prefix = XATTR_HURD_PREFIX,
+	.get = shmem_xattr_handler_get,
+	.set = shmem_xattr_handler_set,
+};
+
 static const struct xattr_handler * const shmem_xattr_handlers[] = {
 	&shmem_security_xattr_handler,
 	&shmem_trusted_xattr_handler,
 	&shmem_user_xattr_handler,
+	&shmem_hurd_xattr_handler,
 	NULL
 };
 
-- 
2.54.0


[-- Attachment #3: Type: text/plain, Size: 161 bytes --]


-- 
Reasonable | Free Software for Correctness | GNU Dezyne -- https://dezyne.org
+Sourcery+ | Correctness for Free Software | https://reasonable-sourcery.coop

Re: [PATCH] shmem: support xattr gnu.* namespace for the Hurd

[Christoph Hellwig]

On Fri, May 15, 2026 at 09:58:05PM +0200, Janneke Nieuwenhuizen wrote:
> >From d8291d06b67db045033664fb440f59001d7755a1 Mon Sep 17 00:00:00 2001
> From: Janneke Nieuwenhuizen <janneke@gnu.org>
> Date: Fri, 15 May 2026 10:12:30 +0200
> Subject: [PATCH] shmem: support xattr gnu.* namespace for the Hurd
> 
> The Hurd gained[0] support for moving the translator and author
> fields out of the inode and into the "gnu.*" xattr namespace.
> 
> In anticipation of that, an xattr INDEX was reserved[1].  The Hurd has
> now been brought into compliance[2] with that, and so has ext4[3].
> 
> This patch adds support for reading and writing such attributes from
> a Linux tmpfs; you can now do something like

No, making bootstrapping a hobbyist OS is not a good reason to bloat
the Linux kernel.  Please patch your bootstrapping code to just use
a user xattr instead.