From mboxrd@z Thu Jan  1 00:00:00 1970
From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: Re: [PATCH] gnu: Mark /gnu/store as needed for boot.
Date: Sat, 14 Jan 2017 22:30:43 +0100
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In-Reply-To: <1484164902-10160-1-git-send-email-jmd@gnu.org> (John
	Darrington's message of "Wed, 11 Jan 2017 21:01:42 +0100")
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To: John Darrington <jmd@gnu.org>
Cc: guix-devel@gnu.org

Hi!

John Darrington <jmd@gnu.org> skribis:

> * gnu/system/file-systems.scm (all-subpaths): New procedure.
> (file-system-needed-for-boot?): Use it to check for ancestors
> of %store-directory.

I guess the idea is to have =E2=80=98needed-for-boot?=E2=80=99 automaticall=
y set for
users who store /gnu or /gnu/store on a separate partition, right?

In =E2=80=98%separate-store-os=E2=80=99 in (gnu tests install), it is set e=
xplicitly:

    (file-systems (cons* (file-system
                           (device "root-fs")
                           (title 'label)
                           (mount-point "/")
                           (type "ext4"))
                         (file-system
                           (device "store-fs")
                           (title 'label)
                           (mount-point "/gnu")
                           (type "ext4")
                           (needed-for-boot? #t)) ;definitely!
                         %base-file-systems))

Making it automatic can help though.

>  (define-inlinable (file-system-needed-for-boot? fs)
> -  "Return true if FS has the 'needed-for-boot?' flag set, or if it's the=
 root
> -file system."
> +  "Return true if FS has the 'needed-for-boot?' flag set, or if it holds
> +the store directory."
>    (or (%file-system-needed-for-boot? fs)
> -      (string=3D? "/" (file-system-mount-point fs))))
> +      (member (file-system-mount-point fs) (all-subpaths (%store-directo=
ry)))))

The problem is that we need to exclude bind mounts, as done in
=E2=80=98store-file-system=E2=80=99 in (gnu system).

What about:

  (define (file-system-needed-for-boot? fs)
    (or (%file-system-needed-for-boot? fs)
        (and (string-prefix? (file-system-mount-point fs) (%store-directory=
))
             (not (memq 'bind-mount (file-system-flags fs))))))

?

Thanks,
Ludo=E2=80=99.