From: "Ludovic Courtès" <ludo@gnu.org>
To: 44169@debbugs.gnu.org
Cc: "Ludovic Courtès" <ludo@gnu.org>
Subject: [bug#44169] [PATCH v2 2/3] services: swap: Allow for UUIDs and file system labels.
Date: Wed, 28 Oct 2020 14:54:56 +0100 [thread overview]
Message-ID: <20201028135457.23335-2-ludo@gnu.org> (raw)
In-Reply-To: <20201028135457.23335-1-ludo@gnu.org>
* gnu/services/base.scm (swap-service-type)[device-lookup, device-name]:
New variables.
Add 'modules' field to 'shepherd-service'. In 'start' and 'stop', use
'device-lookup' to resolve UUIDs and labels.
* doc/guix.texi (operating-system Reference): Adjust accordingly.
---
doc/guix.texi | 34 +++++++++++++++++++++++----
gnu/services/base.scm | 54 +++++++++++++++++++++++++++++++++----------
2 files changed, 71 insertions(+), 17 deletions(-)
diff --git a/doc/guix.texi b/doc/guix.texi
index efb4ea1c47..feb5760129 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -13043,14 +13043,38 @@ A list of mapped devices. @xref{Mapped Devices}.
@item @code{file-systems}
A list of file systems. @xref{File Systems}.
-@item @code{swap-devices} (default: @code{'()})
@cindex swap devices
-A list of strings identifying devices or files to be used for ``swap
+@cindex swap space
+@item @code{swap-devices} (default: @code{'()})
+A list of UUIDs, file system labels, or strings identifying devices or
+files to be used for ``swap
space'' (@pxref{Memory Concepts,,, libc, The GNU C Library Reference
-Manual}). For example, @code{'("/dev/sda3")} or @code{'("/swapfile")}.
+Manual}). Here are some examples:
+
+@table @code
+@item (list (uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb"))
+Use the swap partition with the given UUID. You can learn the UUID of a
+Linux swap partition by running @command{swaplabel @var{device}}, where
+@var{device} is the @file{/dev} file name of that partition.
+
+@item (list (file-system-label "swap"))
+Use the partition with label @code{swap}. Again, the
+@command{swaplabel} command allows you to view and change the label of a
+Linux swap partition.
+
+@item (list "/swapfile")
+Use the file @file{/swapfile} as swap space.
+
+@item (list "/dev/sda3" "/dev/sdb2")
+Use the @file{/dev/sda3} and @file{/dev/sdb2} partitions as swap space.
+We recommend referring to swap devices by UUIDs or labels as shown above
+instead.
+@end table
+
It is possible to specify a swap file in a file system on a mapped
-device, provided that the necessary device mapping and file system are
-also specified. @xref{Mapped Devices} and @ref{File Systems}.
+device (under @file{/dev/mapper}), provided that the necessary device
+mapping and file system are also specified. @xref{Mapped Devices} and
+@ref{File Systems}.
@item @code{users} (default: @code{%base-user-accounts})
@itemx @code{groups} (default: @code{%base-groups})
diff --git a/gnu/services/base.scm b/gnu/services/base.scm
index 37b0a13ea7..07d9089b0a 100644
--- a/gnu/services/base.scm
+++ b/gnu/services/base.scm
@@ -2104,22 +2104,52 @@ instance."
'swap
(lambda (device)
(define requirement
- (if (string-prefix? "/dev/mapper/" device)
+ (if (and (string? device)
+ (string-prefix? "/dev/mapper/" device))
(list (symbol-append 'device-mapping-
(string->symbol (basename device))))
'()))
- (shepherd-service
- (provision (list (symbol-append 'swap- (string->symbol device))))
- (requirement `(udev ,@requirement))
- (documentation "Enable the given swap device.")
- (start #~(lambda ()
- (restart-on-EINTR (swapon #$device))
- #t))
- (stop #~(lambda _
- (restart-on-EINTR (swapoff #$device))
- #f))
- (respawn? #f)))))
+ (define (device-lookup device)
+ ;; The generic 'find-partition' procedures could return a partition
+ ;; that's not swap space, but that's unlikely.
+ (cond ((uuid? device)
+ #~(find-partition-by-uuid #$(uuid-bytevector device)))
+ ((file-system-label? device)
+ #~(find-partition-by-label
+ #$(file-system-label->string device)))
+ (else
+ device)))
+
+ (define service-name
+ (symbol-append 'swap-
+ (string->symbol
+ (cond ((uuid? device)
+ (string-take (uuid->string device) 6))
+ ((file-system-label? device)
+ (file-system-label->string device))
+ (else
+ device)))))
+
+ (with-imported-modules (source-module-closure '((gnu build file-systems)))
+ (shepherd-service
+ (provision (list service-name))
+ (requirement `(udev ,@requirement))
+ (documentation "Enable the given swap device.")
+ (modules `((gnu build file-systems)
+ ,@%default-modules))
+ (start #~(lambda ()
+ (let ((device #$(device-lookup device)))
+ (and device
+ (begin
+ (restart-on-EINTR (swapon device))
+ #t)))))
+ (stop #~(lambda _
+ (let ((device #$(device-lookup device)))
+ (when device
+ (restart-on-EINTR (swapoff device)))
+ #f)))
+ (respawn? #f))))))
(define (swap-service device)
"Return a service that uses @var{device} as a swap device."
--
2.28.0
next prev parent reply other threads:[~2020-10-28 13:56 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-23 9:58 [bug#44169] [PATCH 0/3] Referring to swap with UUIDs and labels Ludovic Courtès
2020-10-23 10:07 ` [bug#44169] [PATCH 1/3] file-systems: Allow swap space lookup by UUID/label Ludovic Courtès
2020-10-23 10:07 ` [bug#44169] [PATCH 2/3] services: swap: Allow for UUIDs and file system labels Ludovic Courtès
2020-10-23 10:07 ` [bug#44169] [PATCH 3/3] installer: Use UUIDs in the 'swap-devices' field Ludovic Courtès
2020-10-23 11:50 ` Mathieu Othacehe
2020-10-26 10:18 ` Ludovic Courtès
2020-10-26 12:06 ` Mathieu Othacehe
2020-10-28 13:58 ` Ludovic Courtès
2020-10-30 0:17 ` bug#44169: " Ludovic Courtès
2020-11-01 18:18 ` [bug#44169] " Mathieu Othacehe
2020-10-23 11:43 ` [bug#44169] [PATCH 1/3] file-systems: Allow swap space lookup by UUID/label Mathieu Othacehe
2020-10-23 16:31 ` Ludovic Courtès
2020-10-23 17:02 ` Mathieu Othacehe
2020-10-24 15:07 ` Ludovic Courtès
2020-10-26 11:56 ` Mathieu Othacehe
2020-10-28 13:54 ` [bug#44169] [PATCH v2 " Ludovic Courtès
2020-10-28 13:54 ` Ludovic Courtès [this message]
2020-10-28 13:54 ` [bug#44169] [PATCH v2 3/3] installer: Use UUIDs in the 'swap-devices' field Ludovic Courtès
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