[PATCH] Add mount option for initramfs

[PATCH] Add mount option for initramfs

[Roger Leigh]

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Hi,

I've attached a trivial patch for an "initramfs" mount option.  The
purpose of this patch is that selected mounts in /etc/fstab can be
identified for mounting in the generated initramfs.  This will
permit e.g. mounting of a separate /etc and /usr and any other
admin-configured filesystems prior to init starting.

Uses: encrypted /etc and unencrypted / and /usr
      separate /usr mounted with rootfs
      - this means libraries and binaries on /usr are available
        from the initramfs onward, solving a whole host of
        problems with e.g. nss and pam modules having dependent
        libs in /usr, etc., which aren't available during boot.

Feel free to change the name to something more generic; this is
intended for use with Debian's initramfs-tools initramfs
generator, but may have potential for cross-distribution use.


Regards,
Roger

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[-- Attachment #2: 0001-mount-Allow-initramfs-dummy-mount-option.patch --]
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>From e588ddb89eb3d8b63291dd7cdad5c134fd221a2d Mon Sep 17 00:00:00 2001
From: Roger Leigh <rleigh@debian.org>
Date: Fri, 16 Dec 2011 23:07:35 +0000
Subject: [PATCH] mount: Allow initramfs dummy mount option

---
 mount/mount.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/mount/mount.c b/mount/mount.c
index 9b444c4..05e82fa 100644
--- a/mount/mount.c
+++ b/mount/mount.c
@@ -202,6 +202,7 @@ static const struct opt_map opt_map[] = {
   { "nostrictatime", 0, 1, MS_STRICTATIME }, /* kernel default atime */
 #endif
   { "nofail",	0, 0, MS_COMMENT},	/* Do not fail if ENOENT on dev */
+  { "initramfs", 0, 0, MS_COMMENT},     /* Mount filesystem in initramfs */
   { NULL,	0, 0, 0		}
 };
 
-- 
1.7.7.3

Re: [PATCH] Add man page entry for initramfs

[Roger Leigh]

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On Fri, Dec 16, 2011 at 11:15:38PM +0000, Roger Leigh wrote:
> Hi,
> 
> I've attached a trivial patch for an "initramfs" mount option.  The
> purpose of this patch is that selected mounts in /etc/fstab can be
> identified for mounting in the generated initramfs.  This will
> permit e.g. mounting of a separate /etc and /usr and any other
> admin-configured filesystems prior to init starting.

The following patch documents this in the mount(8) manpage.


Regards,
Roger

-- 
  .''`.  Roger Leigh
 : :' :  Debian GNU/Linux             http://people.debian.org/~rleigh/
 `. `'   Printing on GNU/Linux?       http://gutenprint.sourceforge.net/
   `-    GPG Public Key: 0x25BFB848   Please GPG sign your mail.

[-- Attachment #2: 0002-mount.8-Document-initramfs-mount-option.patch --]
[-- Type: text/x-diff, Size: 1194 bytes --]

>From 6ea3cf1bdc58d2c1e0124967268d1d1e82c838a4 Mon Sep 17 00:00:00 2001
From: Roger Leigh <rleigh@debian.org>
Date: Sat, 17 Dec 2011 10:11:49 +0000
Subject: [PATCH 2/2] mount.8: Document initramfs mount option

---
 mount/mount.8 |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/mount/mount.8 b/mount/mount.8
index fc352b5..f7be9d3 100644
--- a/mount/mount.8
+++ b/mount/mount.8
@@ -917,6 +917,16 @@ This option implies the options
 (unless overridden by subsequent options, as in the option line
 .BR group,dev,suid ).
 .TP
+.B initramfs
+The filesystem will be mounted by initial initramfs, before the root
+filesystem becomes available.  This permits separation of files
+required for boot onto separate filesystems, such as those in /etc and
+/usr.  This additionally permits selected encryption of files in /etc,
+for example, while leaving the remainder of the files in / and /usr
+unencrypted for performance.  Note that filesystems marked using this
+option may require the running of a tool to update the initramfs
+following any changes.
+.TP
 .B iversion
 Every time the inode is modified, the i_version field will be incremented.
 .TP
-- 
1.7.7.3

Re: [PATCH] Add mount option for initramfs

[Roger Leigh]

On Tue, Dec 20, 2011 at 02:14:40PM +0100, Karel Zak wrote:
> On Fri, Dec 16, 2011 at 11:15:38PM +0000, Roger Leigh wrote:
> >    { "nofail",	0, 0, MS_COMMENT},	/* Do not fail if ENOENT on dev */
> > +  { "initramfs", 0, 0, MS_COMMENT},     /* Mount filesystem in initramfs */
> 
>  I don't think this is the right way. We have to be very conservative
>  with new mount options, especially with options specific for any
>  use case.
> 
>  You can use comment=initramfs and in new mount(8) will be also
>  supported x-* options, then you can use x-initrd or so.

OK, no worries.  I didn't realise you could use the comment syntax
in this way, so either that or x-initramfs/x-initrd will do nicely.


Thanks,
Roger

-- 
  .''`.  Roger Leigh
 : :' :  Debian GNU/Linux             http://people.debian.org/~rleigh/
 `. `'   Printing on GNU/Linux?       http://gutenprint.sourceforge.net/
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Re: [PATCH] Add mount option for initramfs

[Karel Zak]

On Fri, Dec 16, 2011 at 11:15:38PM +0000, Roger Leigh wrote:
>    { "nofail",	0, 0, MS_COMMENT},	/* Do not fail if ENOENT on dev */
> +  { "initramfs", 0, 0, MS_COMMENT},     /* Mount filesystem in initramfs */

 I don't think this is the right way. We have to be very conservative
 with new mount options, especially with options specific for any
 use case.

 You can use comment=initramfs and in new mount(8) will be also
 supported x-* options, then you can use x-initrd or so.

    Karel


-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com