GNU bug report logs - #63182
[PATCH 0/1] Add cachefilesd service

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Felix Lechner <felix.lechner <at> lease-up.com>
To: guix-patches <at> gnu.org
Cc: Felix Lechner <felix.lechner <at> lease-up.com>
Subject: [PATCH 0/1] Add cachefilesd service
Date: Sat, 29 Apr 2023 21:00:08 -0700

Hi,

This bug replaces Bug#41180, which is apparently too old to trigger a CI
pipeline. The patch also required changes because listing serializers "after"
the docstring has been deprecated.

The serializers are still after the docstring but now use some form of record
syntax starting with "(serializer (..))".

Bug#41180 will be closed in the near future with a reference to this bug.

Kind regards
Felix

Felix Lechner (1):
  gnu: services: Add cachefilesd service. (Closes: #41180)

 doc/guix.texi             |  90 +++++++++++++++++
 gnu/local.mk              |   1 +
 gnu/services/linux.scm    | 199 +++++++++++++++++++++++++++++++++++++-
 gnu/tests/cachefilesd.scm |  71 ++++++++++++++
 4 files changed, 360 insertions(+), 1 deletion(-)
 create mode 100644 gnu/tests/cachefilesd.scm


base-commit: 85c137adde84055d78b16d84e5ae4817995bce28
-- 
2.39.2

Message #8 received at 63182 <at> debbugs.gnu.org (full text, mbox):

From: Felix Lechner <felix.lechner <at> lease-up.com>
To: 63182 <at> debbugs.gnu.org
Cc: Bruno Victal <mirai <at> makinata.eu>, me <at> tobias.gr,
 Felix Lechner <felix.lechner <at> lease-up.com>, leo <at> famulari.name
Subject: [PATCH 1/1] gnu: services: Add cachefilesd service. (Closes: #63182)
Date: Sat, 29 Apr 2023 21:02:40 -0700

Thanks to Bruno Victal "mirai" for cooperating on this patch and for
generously sharing a wealth of insights about Guix services.

Thanks to Jean-Baptiste Note for an early version of this service!

We copied the kernel team as a courtesy.

Co-authored-by: Bruno Victal <mirai <at> makinata.eu>
---
 doc/guix.texi             |  90 +++++++++++++++++
 gnu/local.mk              |   1 +
 gnu/services/linux.scm    | 199 +++++++++++++++++++++++++++++++++++++-
 gnu/tests/cachefilesd.scm |  71 ++++++++++++++
 4 files changed, 360 insertions(+), 1 deletion(-)
 create mode 100644 gnu/tests/cachefilesd.scm

diff --git a/doc/guix.texi b/doc/guix.texi
index 46e7fd3908..e9bea38366 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -114,6 +114,7 @@ Copyright @copyright{} 2022 Ivan Vilata-i-Balaguer@*
 Copyright @copyright{} 2023 Giacomo Leidi@*
 Copyright @copyright{} 2022 Antero Mejr@*
 Copyright @copyright{} 2023 Karl Hallsby
+Copyright @copyright{} 2023 Felix Lechner@*
 
 Permission is granted to copy, distribute and/or modify this document
 under the terms of the GNU Free Documentation License, Version 1.3 or
@@ -37656,6 +37657,95 @@ parameters, can be done as follow:
 @end lisp
 @end defvar
 
+@cindex cachefilesd
+@cindex cachefiles
+@cindex fscache
+@subsubheading Cachefilesd Service
+
+The Cachefilesd service starts a daemon that caches network filesystem
+data locally.  It is especially useful for NFS and AFS shares, where it
+reduces latencies for repeated access when reading files.
+
+The daemon can be started as follows:
+
+@lisp
+(service cachefilesd-service-type
+  (cachefilesd-configuration
+    (cache-directory "/var/cache/fscache")))
+@end lisp
+
+@defvar cachefilesd-service-type
+The service type for starting @command{cachefilesd}. The value for this
+service type is a @code{cachefilesd-configuration}, whose only required
+field is @var{cache-directory}.
+
+@end defvar
+
+@c %start of fragment
+@deftp {Data Type} cachefilesd-configuration
+Available @code{cachefilesd-configuration} fields are:
+
+@table @asis
+@item @code{cachefilesd} (default: @code{cachefilesd}) (type: file-like)
+The cachefilesd package to use.
+
+@item @code{debug-output?} (default: @code{#f}) (type: boolean)
+Print debugging output to stderr.
+
+@item @code{use-syslog?} (default: @code{#t}) (type: boolean)
+Log to syslog facility instead of stdout.
+
+@item @code{scan?} (default: @code{#t}) (type: boolean)
+Scan for cachable objects.
+
+@item @code{cache-directory} (type: maybe-string)
+Location of the cache directory.
+
+@item @code{cache-name} (default: @code{"CacheFiles"}) (type: maybe-string)
+Name of cache (keep unique).
+
+@item @code{security-context} (type: maybe-string)
+SELinux security context.
+
+@item @code{pause-culling-for-block-percentage} (default: @code{7}) (type: maybe-non-negative-integer)
+Pause culling when available blocks exceed this percentage.
+
+@item @code{pause-culling-for-file-percentage} (default: @code{7}) (type: maybe-non-negative-integer)
+Pause culling when available files exceed this percentage.
+
+@item @code{resume-culling-for-block-percentage} (default: @code{5}) (type: maybe-non-negative-integer)
+Start culling when available blocks drop below this percentage.
+
+@item @code{resume-culling-for-file-percentage} (default: @code{5}) (type: maybe-non-negative-integer)
+Start culling when available files drop below this percentage.
+
+@item @code{pause-caching-for-block-percentage} (default: @code{1}) (type: maybe-non-negative-integer)
+Pause further allocations when available blocks drop below this
+percentage.
+
+@item @code{pause-caching-for-file-percentage} (default: @code{1}) (type: maybe-non-negative-integer)
+Pause further allocations when available files drop below this
+percentage.
+
+@item @code{log2-table-size} (default: @code{12}) (type: maybe-non-negative-integer)
+Size of tables holding cullable objects in logarithm of base 2.
+
+@item @code{cull?} (default: @code{#t}) (type: boolean)
+Create free space by culling (consumes system load).
+
+@item @code{trace-function-entry-in-kernel-module?} (default: @code{#f}) (type: boolean)
+Trace function entry in the kernel module (for debugging).
+
+@item @code{trace-function-exit-in-kernel-module?} (default: @code{#f}) (type: boolean)
+Trace function exit in the kernel module (for debugging).
+
+@item @code{trace-internal-checkpoints-in-kernel-module?} (default: @code{#f}) (type: boolean)
+Trace internal checkpoints in the kernel module (for debugging).
+
+@end table
+@end deftp
+@c %end of fragment
+
 @cindex rasdaemon
 @cindex Platform Reliability, Availability and Serviceability daemon
 @subsubheading Rasdaemon Service
diff --git a/gnu/local.mk b/gnu/local.mk
index 1a84e5b499..23ed7855d7 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -763,6 +763,7 @@ GNU_SYSTEM_MODULES =				\
   %D%/tests.scm					\
   %D%/tests/audio.scm				\
   %D%/tests/base.scm				\
+  %D%/tests/cachefilesd.scm			\
   %D%/tests/ci.scm				\
   %D%/tests/cups.scm				\
   %D%/tests/databases.scm			\
diff --git a/gnu/services/linux.scm b/gnu/services/linux.scm
index 4f28044112..32517c5c45 100644
--- a/gnu/services/linux.scm
+++ b/gnu/services/linux.scm
@@ -6,6 +6,7 @@
 ;;; Copyright © 2021 B. Wilson <elaexuotee <at> wilsonb.com>
 ;;; Copyright © 2022 Josselin Poiret <dev <at> jpoiret.xyz>
 ;;; Copyright © 2023 Bruno Victal <mirai <at> makinata.eu>
+;;; Copyright © 2023 Felix Lechner <felix.lechner <at> lease-up.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -66,6 +67,28 @@ (define-module (gnu services linux)
 
             kernel-module-loader-service-type
 
+            cachefilesd-configuration
+            cachefilesd-configuration?
+            cachefilesd-configuration-cachefilesd
+            cachefilesd-configuration-debug-output?
+            cachefilesd-configuration-use-syslog?
+            cachefilesd-configuration-scan?
+            cachefilesd-configuration-cache-directory
+            cachefilesd-configuration-cache-name
+            cachefilesd-configuration-security-context
+            cachefilesd-configuration-pause-culling-for-block-percentage
+            cachefilesd-configuration-pause-culling-for-file-percentage
+            cachefilesd-configuration-resume-culling-for-block-percentage
+            cachefilesd-configuration-resume-culling-for-file-percentage
+            cachefilesd-configuration-pause-caching-for-block-percentage
+            cachefilesd-configuration-pause-caching-for-file-percentage
+            cachefilesd-configuration-log2-table-size
+            cachefilesd-configuration-cull?
+            cachefilesd-configuration-trace-function-entry-in-kernel-module
+            cachefilesd-configuration-trace-function-exit-in-kernel-module
+            cachefilesd-configuration-trace-internal-checkpoints-in-kernel-module
+            cachefilesd-service-type
+
             rasdaemon-configuration
             rasdaemon-configuration?
             rasdaemon-configuration-record?
@@ -299,6 +322,180 @@ (define kernel-module-loader-service-type
    (extend append)
    (default-value '())))
 
+
+;;;
+;;; Cachefilesd, an FS-Cache daemon
+;;;
+
+(define (serialize-string variable-symbol value)
+  #~(format #f "~a ~a~%" #$(symbol->string variable-symbol) #$value))
+
+(define-maybe string)
+
+(define (non-negative-integer? val)
+  (and (exact-integer? val) (not (negative? val))))
+
+(define (serialize-non-negative-integer variable-symbol value)
+  #~(format #f "~a ~d~%" #$(symbol->string variable-symbol) #$value))
+
+(define-maybe non-negative-integer)
+
+(define (make-option-serializer option-symbol)
+  (lambda (variable-symbol text)
+    (if (maybe-value-set? text)
+        #~(format #f "~a ~a~%" #$(symbol->string option-symbol) #$text)
+        "")))
+
+(define (make-percentage-threshold-serializer threshold-symbol)
+  (lambda (variable-symbol percentage)
+    (if (maybe-value-set? percentage)
+        #~(format #f "~a ~a%~%" #$(symbol->string threshold-symbol) #$percentage)
+        "")))
+
+(define-configuration cachefilesd-configuration
+  (cachefilesd
+   (file-like cachefilesd)
+   "The cachefilesd package to use."
+   (serializer empty-serializer))
+
+  ;; command-line options
+  (debug-output?
+   (boolean #f)
+   "Print debugging output to stderr."
+   (serializer empty-serializer))
+
+  (use-syslog?
+   (boolean #t)
+   "Log to syslog facility instead of stdout."
+   (serializer empty-serializer))
+
+  ;; culling is part of the configuration file
+  ;; despite the name of the command-line option
+  (scan?
+   (boolean #t)
+   "Scan for cachable objects."
+   (serializer empty-serializer))
+
+  ;; sole required field in the configuration file
+  (cache-directory
+   maybe-string
+   "Location of the cache directory."
+   (serializer (make-option-serializer 'dir)))
+
+  (cache-name
+   (maybe-string "CacheFiles")
+   "Name of cache (keep unique)."
+   (serializer (make-option-serializer 'tag)))
+
+  (security-context
+   maybe-string
+   "SELinux security context."
+   (serializer (make-option-serializer 'secctx)))
+
+  ;; percentage thresholds in the configuration file
+  (pause-culling-for-block-percentage
+   (maybe-non-negative-integer 7)
+   "Pause culling when available blocks exceed this percentage."
+   (serializer (make-percentage-threshold-serializer 'brun)))
+
+  (pause-culling-for-file-percentage
+   (maybe-non-negative-integer 7)
+   "Pause culling when available files exceed this percentage."
+   (serializer (make-percentage-threshold-serializer 'frun)))
+
+  (resume-culling-for-block-percentage
+   (maybe-non-negative-integer 5)
+   "Start culling when available blocks drop below this percentage."
+   (serializer (make-percentage-threshold-serializer 'bcull)))
+
+  (resume-culling-for-file-percentage
+   (maybe-non-negative-integer 5)
+   "Start culling when available files drop below this percentage."
+   (serializer (make-percentage-threshold-serializer 'fcull)))
+
+  (pause-caching-for-block-percentage
+   (maybe-non-negative-integer 1)
+   "Pause further allocations when available blocks drop below this percentage."
+   (serializer (make-percentage-threshold-serializer 'bstop)))
+
+  (pause-caching-for-file-percentage
+   (maybe-non-negative-integer 1)
+   "Pause further allocations when available files drop below this percentage."
+   (serializer (make-percentage-threshold-serializer 'fstop)))
+
+  ;; run time optimizations in the configuration file
+  (log2-table-size
+   (maybe-non-negative-integer 12)
+   "Size of tables holding cullable objects in logarithm of base 2."
+   (serializer (make-option-serializer 'culltable)))
+
+  (cull?
+   (boolean #t)
+   "Create free space by culling (consumes system load)."
+   (serializer
+    (lambda (variable-symbol value)
+      (if value "" "nocull\n"))))
+
+  ;; kernel module debugging in the configuration file
+  (trace-function-entry-in-kernel-module?
+   (boolean #f)
+   "Trace function entry in the kernel module (for debugging)."
+   (serializer empty-serializer))
+
+  (trace-function-exit-in-kernel-module?
+   (boolean #f)
+   "Trace function exit in the kernel module (for debugging)."
+   (serializer empty-serializer))
+
+  (trace-internal-checkpoints-in-kernel-module?
+   (boolean #f)
+   "Trace internal checkpoints in the kernel module (for debugging)."
+   (serializer empty-serializer)))
+
+(define (serialize-cachefilesd-configuration configuration)
+  (mixed-text-file
+   "cachefilesd.conf"
+   (serialize-configuration configuration cachefilesd-configuration-fields)))
+
+(define (cachefilesd-shepherd-service config)
+  "Return a list of <shepherd-service> for cachefilesd for CONFIG."
+  (match-record
+      config <cachefilesd-configuration> (cachefilesd
+                                          debug-output?
+                                          use-syslog?
+                                          scan?
+                                          cache-directory)
+      (let ((configuration-file (serialize-cachefilesd-configuration config)))
+        (shepherd-service
+         (documentation "Run the cachefilesd daemon for FS-Cache.")
+         (provision '(cachefilesd))
+         (requirement (append '(file-systems)
+                              (if use-syslog? '(syslogd) '())))
+         (start #~(begin
+                    (and=> #$(maybe-value cache-directory) mkdir-p)
+                    (make-forkexec-constructor
+                     `(#$(file-append cachefilesd "/sbin/cachefilesd")
+                       ;; do not detach
+                       "-n"
+                       #$@(if debug-output? '("-d") '())
+                       #$@(if use-syslog? '() '("-s"))
+                       #$@(if scan? '() '("-N"))
+                       "-f" #$configuration-file))))
+         (stop #~(make-kill-destructor))))))
+
+(define cachefilesd-service-type
+  (service-type
+   (name 'cachefilesd)
+   (description
+    "Run the FS-Cache backend daemon @command{cachefilesd}.")
+   (extensions
+    (list
+     (service-extension kernel-module-loader-service-type
+                        (const '("cachefiles")))
+     (service-extension shepherd-root-service-type
+                        (compose list cachefilesd-shepherd-service))))
+   (default-value (cachefilesd-configuration))))
+
 
 ;;;
 ;;; Reliability, Availability, and Serviceability (RAS) daemon
@@ -344,7 +541,7 @@ (define rasdaemon-service-type
 
 
 ;;;
-;;; Kernel module loader.
+;;; Zram device
 ;;;
 
 (define-record-type* <zram-device-configuration>
diff --git a/gnu/tests/cachefilesd.scm b/gnu/tests/cachefilesd.scm
new file mode 100644
index 0000000000..7f5d513067
--- /dev/null
+++ b/gnu/tests/cachefilesd.scm
@@ -0,0 +1,71 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2017 Peter Mikkelsen <petermikkelsen10 <at> gmail.com>
+;;; Copyright © 2022 Bruno Victal <mirai <at> makinata.eu>
+;;; Copyright © 2023 Felix Lechner <felix.lechner <at> lease-up.com>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (gnu tests cachefilesd)
+  #:use-module (gnu tests)
+  #:use-module (gnu system)
+  #:use-module (gnu system vm)
+  #:use-module (gnu services)
+  #:use-module (gnu services linux)
+  #:use-module (guix gexp)
+  #:export (%test-cachefilesd))
+
+(define %cachefilesd-os
+  (simple-operating-system
+   (service cachefilesd-service-type
+            (cachefilesd-configuration
+             (cache-directory "/var/cache/fscache")))))
+
+(define (run-cachefilesd-test)
+  "Run tests in %cachefilesd-os, which has cachefilesd running."
+  (define os
+    (marionette-operating-system
+     %cachefilesd-os
+     #:imported-modules '((gnu services herd))))
+
+  (define vm
+    (virtual-machine os))
+
+  (define test
+    (with-imported-modules '((gnu build marionette))
+      #~(begin
+          (use-modules (srfi srfi-64)
+                       (gnu build marionette))
+          (define marionette
+            (make-marionette (list #$vm)))
+
+          (test-runner-current (system-test-runner #$output))
+          (test-begin "cachefilesd")
+
+          (test-assert "service is running"
+            (marionette-eval
+             '(begin
+                (use-modules (gnu services herd))
+                (start-service 'cachefilesd))
+             marionette))
+
+          (test-end))))
+  (gexp->derivation "cachefilesd-test" test))
+
+(define %test-cachefilesd
+  (system-test
+   (name "cachefilesd")
+   (description "Test that the cachefilesd runs when started.")
+   (value (run-cachefilesd-test))))
-- 
2.39.2

Message #11 received at 63182 <at> debbugs.gnu.org (full text, mbox):

From: Felix Lechner <felix.lechner <at> lease-up.com>
To: 63182 <at> debbugs.gnu.org
Subject: Also available in Juix channel
Date: Sat, 29 Apr 2023 21:15:00 -0700

Hi,

Pending acceptance of this patch, interested users can test the new
service in the Juix channel. [1]

Kind regards
Felix

[1] https://codeberg.org/lechner/juix

Message #14 received at 63182 <at> debbugs.gnu.org (full text, mbox):

From: Felix Lechner <felix.lechner <at> lease-up.com>
To: 63182 <at> debbugs.gnu.org
Subject: rebased
Date: Fri, 12 May 2023 11:49:22 -0700

This patch series was rebased to to changes on the 'master' branch.

Message #17 received at 63182 <at> debbugs.gnu.org (full text, mbox):

From: Felix Lechner <felix.lechner <at> lease-up.com>
To: 63182 <at> debbugs.gnu.org
Cc: Bruno Victal <mirai <at> makinata.eu>,
 Felix Lechner <felix.lechner <at> lease-up.com>
Subject: [PATCH v2] gnu: services: Add cachefilesd service. (Closes: #63182)
Date: Fri, 12 May 2023 11:50:22 -0700

Thanks to Bruno Victal "mirai" for cooperating on this patch and for
generously sharing a wealth of insights about Guix services.

Thanks to Jean-Baptiste Note for an early version of this service!

Co-authored-by: Bruno Victal <mirai <at> makinata.eu>
---
 doc/guix.texi             |  90 +++++++++++++++++
 gnu/local.mk              |   1 +
 gnu/services/linux.scm    | 199 +++++++++++++++++++++++++++++++++++++-
 gnu/tests/cachefilesd.scm |  71 ++++++++++++++
 4 files changed, 360 insertions(+), 1 deletion(-)
 create mode 100644 gnu/tests/cachefilesd.scm

diff --git a/doc/guix.texi b/doc/guix.texi
index 09763d86ab..270b3f5958 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -115,6 +115,7 @@ Copyright @copyright{} 2023 Giacomo Leidi@*
 Copyright @copyright{} 2022 Antero Mejr@*
 Copyright @copyright{} 2023 Karl Hallsby
 Copyright @copyright{} 2023 Nathaniel Nicandro
+Copyright @copyright{} 2023 Felix Lechner@*
 
 Permission is granted to copy, distribute and/or modify this document
 under the terms of the GNU Free Documentation License, Version 1.3 or
@@ -37990,6 +37991,95 @@ parameters, can be done as follow:
 @end lisp
 @end defvar
 
+@cindex cachefilesd
+@cindex cachefiles
+@cindex fscache
+@subsubheading Cachefilesd Service
+
+The Cachefilesd service starts a daemon that caches network filesystem
+data locally.  It is especially useful for NFS and AFS shares, where it
+reduces latencies for repeated access when reading files.
+
+The daemon can be started as follows:
+
+@lisp
+(service cachefilesd-service-type
+  (cachefilesd-configuration
+    (cache-directory "/var/cache/fscache")))
+@end lisp
+
+@defvar cachefilesd-service-type
+The service type for starting @command{cachefilesd}. The value for this
+service type is a @code{cachefilesd-configuration}, whose only required
+field is @var{cache-directory}.
+
+@end defvar
+
+@c %start of fragment
+@deftp {Data Type} cachefilesd-configuration
+Available @code{cachefilesd-configuration} fields are:
+
+@table @asis
+@item @code{cachefilesd} (default: @code{cachefilesd}) (type: file-like)
+The cachefilesd package to use.
+
+@item @code{debug-output?} (default: @code{#f}) (type: boolean)
+Print debugging output to stderr.
+
+@item @code{use-syslog?} (default: @code{#t}) (type: boolean)
+Log to syslog facility instead of stdout.
+
+@item @code{scan?} (default: @code{#t}) (type: boolean)
+Scan for cachable objects.
+
+@item @code{cache-directory} (type: maybe-string)
+Location of the cache directory.
+
+@item @code{cache-name} (default: @code{"CacheFiles"}) (type: maybe-string)
+Name of cache (keep unique).
+
+@item @code{security-context} (type: maybe-string)
+SELinux security context.
+
+@item @code{pause-culling-for-block-percentage} (default: @code{7}) (type: maybe-non-negative-integer)
+Pause culling when available blocks exceed this percentage.
+
+@item @code{pause-culling-for-file-percentage} (default: @code{7}) (type: maybe-non-negative-integer)
+Pause culling when available files exceed this percentage.
+
+@item @code{resume-culling-for-block-percentage} (default: @code{5}) (type: maybe-non-negative-integer)
+Start culling when available blocks drop below this percentage.
+
+@item @code{resume-culling-for-file-percentage} (default: @code{5}) (type: maybe-non-negative-integer)
+Start culling when available files drop below this percentage.
+
+@item @code{pause-caching-for-block-percentage} (default: @code{1}) (type: maybe-non-negative-integer)
+Pause further allocations when available blocks drop below this
+percentage.
+
+@item @code{pause-caching-for-file-percentage} (default: @code{1}) (type: maybe-non-negative-integer)
+Pause further allocations when available files drop below this
+percentage.
+
+@item @code{log2-table-size} (default: @code{12}) (type: maybe-non-negative-integer)
+Size of tables holding cullable objects in logarithm of base 2.
+
+@item @code{cull?} (default: @code{#t}) (type: boolean)
+Create free space by culling (consumes system load).
+
+@item @code{trace-function-entry-in-kernel-module?} (default: @code{#f}) (type: boolean)
+Trace function entry in the kernel module (for debugging).
+
+@item @code{trace-function-exit-in-kernel-module?} (default: @code{#f}) (type: boolean)
+Trace function exit in the kernel module (for debugging).
+
+@item @code{trace-internal-checkpoints-in-kernel-module?} (default: @code{#f}) (type: boolean)
+Trace internal checkpoints in the kernel module (for debugging).
+
+@end table
+@end deftp
+@c %end of fragment
+
 @cindex rasdaemon
 @cindex Platform Reliability, Availability and Serviceability daemon
 @subsubheading Rasdaemon Service
diff --git a/gnu/local.mk b/gnu/local.mk
index d31b40f3bf..a9e6f54088 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -765,6 +765,7 @@ GNU_SYSTEM_MODULES =				\
   %D%/tests.scm					\
   %D%/tests/audio.scm				\
   %D%/tests/base.scm				\
+  %D%/tests/cachefilesd.scm			\
   %D%/tests/ci.scm				\
   %D%/tests/cups.scm				\
   %D%/tests/databases.scm			\
diff --git a/gnu/services/linux.scm b/gnu/services/linux.scm
index d105c42850..e42ef1ae97 100644
--- a/gnu/services/linux.scm
+++ b/gnu/services/linux.scm
@@ -6,6 +6,7 @@
 ;;; Copyright © 2021 B. Wilson <elaexuotee <at> wilsonb.com>
 ;;; Copyright © 2022 Josselin Poiret <dev <at> jpoiret.xyz>
 ;;; Copyright © 2023 Bruno Victal <mirai <at> makinata.eu>
+;;; Copyright © 2023 Felix Lechner <felix.lechner <at> lease-up.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -67,6 +68,28 @@ (define-module (gnu services linux)
 
             kernel-module-loader-service-type
 
+            cachefilesd-configuration
+            cachefilesd-configuration?
+            cachefilesd-configuration-cachefilesd
+            cachefilesd-configuration-debug-output?
+            cachefilesd-configuration-use-syslog?
+            cachefilesd-configuration-scan?
+            cachefilesd-configuration-cache-directory
+            cachefilesd-configuration-cache-name
+            cachefilesd-configuration-security-context
+            cachefilesd-configuration-pause-culling-for-block-percentage
+            cachefilesd-configuration-pause-culling-for-file-percentage
+            cachefilesd-configuration-resume-culling-for-block-percentage
+            cachefilesd-configuration-resume-culling-for-file-percentage
+            cachefilesd-configuration-pause-caching-for-block-percentage
+            cachefilesd-configuration-pause-caching-for-file-percentage
+            cachefilesd-configuration-log2-table-size
+            cachefilesd-configuration-cull?
+            cachefilesd-configuration-trace-function-entry-in-kernel-module
+            cachefilesd-configuration-trace-function-exit-in-kernel-module
+            cachefilesd-configuration-trace-internal-checkpoints-in-kernel-module
+            cachefilesd-service-type
+
             rasdaemon-configuration
             rasdaemon-configuration?
             rasdaemon-configuration-record?
@@ -306,6 +329,180 @@ (define kernel-module-loader-service-type
    (extend append)
    (default-value '())))
 
+
+;;;
+;;; Cachefilesd, an FS-Cache daemon
+;;;
+
+(define (serialize-string variable-symbol value)
+  #~(format #f "~a ~a~%" #$(symbol->string variable-symbol) #$value))
+
+(define-maybe string)
+
+(define (non-negative-integer? val)
+  (and (exact-integer? val) (not (negative? val))))
+
+(define (serialize-non-negative-integer variable-symbol value)
+  #~(format #f "~a ~d~%" #$(symbol->string variable-symbol) #$value))
+
+(define-maybe non-negative-integer)
+
+(define (make-option-serializer option-symbol)
+  (lambda (variable-symbol text)
+    (if (maybe-value-set? text)
+        #~(format #f "~a ~a~%" #$(symbol->string option-symbol) #$text)
+        "")))
+
+(define (make-percentage-threshold-serializer threshold-symbol)
+  (lambda (variable-symbol percentage)
+    (if (maybe-value-set? percentage)
+        #~(format #f "~a ~a%~%" #$(symbol->string threshold-symbol) #$percentage)
+        "")))
+
+(define-configuration cachefilesd-configuration
+  (cachefilesd
+   (file-like cachefilesd)
+   "The cachefilesd package to use."
+   (serializer empty-serializer))
+
+  ;; command-line options
+  (debug-output?
+   (boolean #f)
+   "Print debugging output to stderr."
+   (serializer empty-serializer))
+
+  (use-syslog?
+   (boolean #t)
+   "Log to syslog facility instead of stdout."
+   (serializer empty-serializer))
+
+  ;; culling is part of the configuration file
+  ;; despite the name of the command-line option
+  (scan?
+   (boolean #t)
+   "Scan for cachable objects."
+   (serializer empty-serializer))
+
+  ;; sole required field in the configuration file
+  (cache-directory
+   maybe-string
+   "Location of the cache directory."
+   (serializer (make-option-serializer 'dir)))
+
+  (cache-name
+   (maybe-string "CacheFiles")
+   "Name of cache (keep unique)."
+   (serializer (make-option-serializer 'tag)))
+
+  (security-context
+   maybe-string
+   "SELinux security context."
+   (serializer (make-option-serializer 'secctx)))
+
+  ;; percentage thresholds in the configuration file
+  (pause-culling-for-block-percentage
+   (maybe-non-negative-integer 7)
+   "Pause culling when available blocks exceed this percentage."
+   (serializer (make-percentage-threshold-serializer 'brun)))
+
+  (pause-culling-for-file-percentage
+   (maybe-non-negative-integer 7)
+   "Pause culling when available files exceed this percentage."
+   (serializer (make-percentage-threshold-serializer 'frun)))
+
+  (resume-culling-for-block-percentage
+   (maybe-non-negative-integer 5)
+   "Start culling when available blocks drop below this percentage."
+   (serializer (make-percentage-threshold-serializer 'bcull)))
+
+  (resume-culling-for-file-percentage
+   (maybe-non-negative-integer 5)
+   "Start culling when available files drop below this percentage."
+   (serializer (make-percentage-threshold-serializer 'fcull)))
+
+  (pause-caching-for-block-percentage
+   (maybe-non-negative-integer 1)
+   "Pause further allocations when available blocks drop below this percentage."
+   (serializer (make-percentage-threshold-serializer 'bstop)))
+
+  (pause-caching-for-file-percentage
+   (maybe-non-negative-integer 1)
+   "Pause further allocations when available files drop below this percentage."
+   (serializer (make-percentage-threshold-serializer 'fstop)))
+
+  ;; run time optimizations in the configuration file
+  (log2-table-size
+   (maybe-non-negative-integer 12)
+   "Size of tables holding cullable objects in logarithm of base 2."
+   (serializer (make-option-serializer 'culltable)))
+
+  (cull?
+   (boolean #t)
+   "Create free space by culling (consumes system load)."
+   (serializer
+    (lambda (variable-symbol value)
+      (if value "" "nocull\n"))))
+
+  ;; kernel module debugging in the configuration file
+  (trace-function-entry-in-kernel-module?
+   (boolean #f)
+   "Trace function entry in the kernel module (for debugging)."
+   (serializer empty-serializer))
+
+  (trace-function-exit-in-kernel-module?
+   (boolean #f)
+   "Trace function exit in the kernel module (for debugging)."
+   (serializer empty-serializer))
+
+  (trace-internal-checkpoints-in-kernel-module?
+   (boolean #f)
+   "Trace internal checkpoints in the kernel module (for debugging)."
+   (serializer empty-serializer)))
+
+(define (serialize-cachefilesd-configuration configuration)
+  (mixed-text-file
+   "cachefilesd.conf"
+   (serialize-configuration configuration cachefilesd-configuration-fields)))
+
+(define (cachefilesd-shepherd-service config)
+  "Return a list of <shepherd-service> for cachefilesd for CONFIG."
+  (match-record
+      config <cachefilesd-configuration> (cachefilesd
+                                          debug-output?
+                                          use-syslog?
+                                          scan?
+                                          cache-directory)
+      (let ((configuration-file (serialize-cachefilesd-configuration config)))
+        (shepherd-service
+         (documentation "Run the cachefilesd daemon for FS-Cache.")
+         (provision '(cachefilesd))
+         (requirement (append '(file-systems)
+                              (if use-syslog? '(syslogd) '())))
+         (start #~(begin
+                    (and=> #$(maybe-value cache-directory) mkdir-p)
+                    (make-forkexec-constructor
+                     `(#$(file-append cachefilesd "/sbin/cachefilesd")
+                       ;; do not detach
+                       "-n"
+                       #$@(if debug-output? '("-d") '())
+                       #$@(if use-syslog? '() '("-s"))
+                       #$@(if scan? '() '("-N"))
+                       "-f" #$configuration-file))))
+         (stop #~(make-kill-destructor))))))
+
+(define cachefilesd-service-type
+  (service-type
+   (name 'cachefilesd)
+   (description
+    "Run the FS-Cache backend daemon @command{cachefilesd}.")
+   (extensions
+    (list
+     (service-extension kernel-module-loader-service-type
+                        (const '("cachefiles")))
+     (service-extension shepherd-root-service-type
+                        (compose list cachefilesd-shepherd-service))))
+   (default-value (cachefilesd-configuration))))
+
 
 ;;;
 ;;; Reliability, Availability, and Serviceability (RAS) daemon
@@ -351,7 +548,7 @@ (define rasdaemon-service-type
 
 
 ;;;
-;;; Kernel module loader.
+;;; Zram device
 ;;;
 
 (define-record-type* <zram-device-configuration>
diff --git a/gnu/tests/cachefilesd.scm b/gnu/tests/cachefilesd.scm
new file mode 100644
index 0000000000..7f5d513067
--- /dev/null
+++ b/gnu/tests/cachefilesd.scm
@@ -0,0 +1,71 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2017 Peter Mikkelsen <petermikkelsen10 <at> gmail.com>
+;;; Copyright © 2022 Bruno Victal <mirai <at> makinata.eu>
+;;; Copyright © 2023 Felix Lechner <felix.lechner <at> lease-up.com>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (gnu tests cachefilesd)
+  #:use-module (gnu tests)
+  #:use-module (gnu system)
+  #:use-module (gnu system vm)
+  #:use-module (gnu services)
+  #:use-module (gnu services linux)
+  #:use-module (guix gexp)
+  #:export (%test-cachefilesd))
+
+(define %cachefilesd-os
+  (simple-operating-system
+   (service cachefilesd-service-type
+            (cachefilesd-configuration
+             (cache-directory "/var/cache/fscache")))))
+
+(define (run-cachefilesd-test)
+  "Run tests in %cachefilesd-os, which has cachefilesd running."
+  (define os
+    (marionette-operating-system
+     %cachefilesd-os
+     #:imported-modules '((gnu services herd))))
+
+  (define vm
+    (virtual-machine os))
+
+  (define test
+    (with-imported-modules '((gnu build marionette))
+      #~(begin
+          (use-modules (srfi srfi-64)
+                       (gnu build marionette))
+          (define marionette
+            (make-marionette (list #$vm)))
+
+          (test-runner-current (system-test-runner #$output))
+          (test-begin "cachefilesd")
+
+          (test-assert "service is running"
+            (marionette-eval
+             '(begin
+                (use-modules (gnu services herd))
+                (start-service 'cachefilesd))
+             marionette))
+
+          (test-end))))
+  (gexp->derivation "cachefilesd-test" test))
+
+(define %test-cachefilesd
+  (system-test
+   (name "cachefilesd")
+   (description "Test that the cachefilesd runs when started.")
+   (value (run-cachefilesd-test))))
-- 
2.40.1

Message #20 received at 63182 <at> debbugs.gnu.org (full text, mbox):

From: Felix Lechner <felix.lechner <at> lease-up.com>
To: 63182 <at> debbugs.gnu.org
Cc: Bruno Victal <mirai <at> makinata.eu>,
 Felix Lechner <felix.lechner <at> lease-up.com>
Subject: [PATCH v2] gnu: services: Add cachefilesd service. (Closes: #63182)
Date: Sun, 28 May 2023 16:36:31 -0700

Thanks to Bruno Victal "mirai" for cooperating on this patch and for
generously sharing a wealth of insights about Guix services.

Thanks to Jean-Baptiste Note for an early version of this service!

Co-authored-by: Bruno Victal <mirai <at> makinata.eu>
---
Rebased for changes in guix.texi.

doc/guix.texi             |  90 +++++++++++++++++
 gnu/local.mk              |   1 +
 gnu/services/linux.scm    | 199 +++++++++++++++++++++++++++++++++++++-
 gnu/tests/cachefilesd.scm |  71 ++++++++++++++
 4 files changed, 360 insertions(+), 1 deletion(-)
 create mode 100644 gnu/tests/cachefilesd.scm

diff --git a/doc/guix.texi b/doc/guix.texi
index 31dc33fb97..304a61603d 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -115,6 +115,7 @@ Copyright @copyright{} 2023 Giacomo Leidi@*
 Copyright @copyright{} 2022 Antero Mejr@*
 Copyright @copyright{} 2023 Karl Hallsby@*
 Copyright @copyright{} 2023 Nathaniel Nicandro@*
+Copyright @copyright{} 2023 Felix Lechner@*
 
 Permission is granted to copy, distribute and/or modify this document
 under the terms of the GNU Free Documentation License, Version 1.3 or
@@ -38062,6 +38063,95 @@ parameters, can be done as follow:
 @end lisp
 @end defvar
 
+@cindex cachefilesd
+@cindex cachefiles
+@cindex fscache
+@subsubheading Cachefilesd Service
+
+The Cachefilesd service starts a daemon that caches network filesystem
+data locally.  It is especially useful for NFS and AFS shares, where it
+reduces latencies for repeated access when reading files.
+
+The daemon can be started as follows:
+
+@lisp
+(service cachefilesd-service-type
+  (cachefilesd-configuration
+    (cache-directory "/var/cache/fscache")))
+@end lisp
+
+@defvar cachefilesd-service-type
+The service type for starting @command{cachefilesd}. The value for this
+service type is a @code{cachefilesd-configuration}, whose only required
+field is @var{cache-directory}.
+
+@end defvar
+
+@c %start of fragment
+@deftp {Data Type} cachefilesd-configuration
+Available @code{cachefilesd-configuration} fields are:
+
+@table @asis
+@item @code{cachefilesd} (default: @code{cachefilesd}) (type: file-like)
+The cachefilesd package to use.
+
+@item @code{debug-output?} (default: @code{#f}) (type: boolean)
+Print debugging output to stderr.
+
+@item @code{use-syslog?} (default: @code{#t}) (type: boolean)
+Log to syslog facility instead of stdout.
+
+@item @code{scan?} (default: @code{#t}) (type: boolean)
+Scan for cachable objects.
+
+@item @code{cache-directory} (type: maybe-string)
+Location of the cache directory.
+
+@item @code{cache-name} (default: @code{"CacheFiles"}) (type: maybe-string)
+Name of cache (keep unique).
+
+@item @code{security-context} (type: maybe-string)
+SELinux security context.
+
+@item @code{pause-culling-for-block-percentage} (default: @code{7}) (type: maybe-non-negative-integer)
+Pause culling when available blocks exceed this percentage.
+
+@item @code{pause-culling-for-file-percentage} (default: @code{7}) (type: maybe-non-negative-integer)
+Pause culling when available files exceed this percentage.
+
+@item @code{resume-culling-for-block-percentage} (default: @code{5}) (type: maybe-non-negative-integer)
+Start culling when available blocks drop below this percentage.
+
+@item @code{resume-culling-for-file-percentage} (default: @code{5}) (type: maybe-non-negative-integer)
+Start culling when available files drop below this percentage.
+
+@item @code{pause-caching-for-block-percentage} (default: @code{1}) (type: maybe-non-negative-integer)
+Pause further allocations when available blocks drop below this
+percentage.
+
+@item @code{pause-caching-for-file-percentage} (default: @code{1}) (type: maybe-non-negative-integer)
+Pause further allocations when available files drop below this
+percentage.
+
+@item @code{log2-table-size} (default: @code{12}) (type: maybe-non-negative-integer)
+Size of tables holding cullable objects in logarithm of base 2.
+
+@item @code{cull?} (default: @code{#t}) (type: boolean)
+Create free space by culling (consumes system load).
+
+@item @code{trace-function-entry-in-kernel-module?} (default: @code{#f}) (type: boolean)
+Trace function entry in the kernel module (for debugging).
+
+@item @code{trace-function-exit-in-kernel-module?} (default: @code{#f}) (type: boolean)
+Trace function exit in the kernel module (for debugging).
+
+@item @code{trace-internal-checkpoints-in-kernel-module?} (default: @code{#f}) (type: boolean)
+Trace internal checkpoints in the kernel module (for debugging).
+
+@end table
+@end deftp
+@c %end of fragment
+
 @cindex rasdaemon
 @cindex Platform Reliability, Availability and Serviceability daemon
 @subsubheading Rasdaemon Service
diff --git a/gnu/local.mk b/gnu/local.mk
index 73370dcc78..8f419880f7 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -766,6 +766,7 @@ GNU_SYSTEM_MODULES =				\
   %D%/tests.scm					\
   %D%/tests/audio.scm				\
   %D%/tests/base.scm				\
+  %D%/tests/cachefilesd.scm			\
   %D%/tests/ci.scm				\
   %D%/tests/cups.scm				\
   %D%/tests/databases.scm			\
diff --git a/gnu/services/linux.scm b/gnu/services/linux.scm
index d105c42850..e42ef1ae97 100644
--- a/gnu/services/linux.scm
+++ b/gnu/services/linux.scm
@@ -6,6 +6,7 @@
 ;;; Copyright © 2021 B. Wilson <elaexuotee <at> wilsonb.com>
 ;;; Copyright © 2022 Josselin Poiret <dev <at> jpoiret.xyz>
 ;;; Copyright © 2023 Bruno Victal <mirai <at> makinata.eu>
+;;; Copyright © 2023 Felix Lechner <felix.lechner <at> lease-up.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -67,6 +68,28 @@ (define-module (gnu services linux)
 
             kernel-module-loader-service-type
 
+            cachefilesd-configuration
+            cachefilesd-configuration?
+            cachefilesd-configuration-cachefilesd
+            cachefilesd-configuration-debug-output?
+            cachefilesd-configuration-use-syslog?
+            cachefilesd-configuration-scan?
+            cachefilesd-configuration-cache-directory
+            cachefilesd-configuration-cache-name
+            cachefilesd-configuration-security-context
+            cachefilesd-configuration-pause-culling-for-block-percentage
+            cachefilesd-configuration-pause-culling-for-file-percentage
+            cachefilesd-configuration-resume-culling-for-block-percentage
+            cachefilesd-configuration-resume-culling-for-file-percentage
+            cachefilesd-configuration-pause-caching-for-block-percentage
+            cachefilesd-configuration-pause-caching-for-file-percentage
+            cachefilesd-configuration-log2-table-size
+            cachefilesd-configuration-cull?
+            cachefilesd-configuration-trace-function-entry-in-kernel-module
+            cachefilesd-configuration-trace-function-exit-in-kernel-module
+            cachefilesd-configuration-trace-internal-checkpoints-in-kernel-module
+            cachefilesd-service-type
+
             rasdaemon-configuration
             rasdaemon-configuration?
             rasdaemon-configuration-record?
@@ -306,6 +329,180 @@ (define kernel-module-loader-service-type
    (extend append)
    (default-value '())))
 
+
+;;;
+;;; Cachefilesd, an FS-Cache daemon
+;;;
+
+(define (serialize-string variable-symbol value)
+  #~(format #f "~a ~a~%" #$(symbol->string variable-symbol) #$value))
+
+(define-maybe string)
+
+(define (non-negative-integer? val)
+  (and (exact-integer? val) (not (negative? val))))
+
+(define (serialize-non-negative-integer variable-symbol value)
+  #~(format #f "~a ~d~%" #$(symbol->string variable-symbol) #$value))
+
+(define-maybe non-negative-integer)
+
+(define (make-option-serializer option-symbol)
+  (lambda (variable-symbol text)
+    (if (maybe-value-set? text)
+        #~(format #f "~a ~a~%" #$(symbol->string option-symbol) #$text)
+        "")))
+
+(define (make-percentage-threshold-serializer threshold-symbol)
+  (lambda (variable-symbol percentage)
+    (if (maybe-value-set? percentage)
+        #~(format #f "~a ~a%~%" #$(symbol->string threshold-symbol) #$percentage)
+        "")))
+
+(define-configuration cachefilesd-configuration
+  (cachefilesd
+   (file-like cachefilesd)
+   "The cachefilesd package to use."
+   (serializer empty-serializer))
+
+  ;; command-line options
+  (debug-output?
+   (boolean #f)
+   "Print debugging output to stderr."
+   (serializer empty-serializer))
+
+  (use-syslog?
+   (boolean #t)
+   "Log to syslog facility instead of stdout."
+   (serializer empty-serializer))
+
+  ;; culling is part of the configuration file
+  ;; despite the name of the command-line option
+  (scan?
+   (boolean #t)
+   "Scan for cachable objects."
+   (serializer empty-serializer))
+
+  ;; sole required field in the configuration file
+  (cache-directory
+   maybe-string
+   "Location of the cache directory."
+   (serializer (make-option-serializer 'dir)))
+
+  (cache-name
+   (maybe-string "CacheFiles")
+   "Name of cache (keep unique)."
+   (serializer (make-option-serializer 'tag)))
+
+  (security-context
+   maybe-string
+   "SELinux security context."
+   (serializer (make-option-serializer 'secctx)))
+
+  ;; percentage thresholds in the configuration file
+  (pause-culling-for-block-percentage
+   (maybe-non-negative-integer 7)
+   "Pause culling when available blocks exceed this percentage."
+   (serializer (make-percentage-threshold-serializer 'brun)))
+
+  (pause-culling-for-file-percentage
+   (maybe-non-negative-integer 7)
+   "Pause culling when available files exceed this percentage."
+   (serializer (make-percentage-threshold-serializer 'frun)))
+
+  (resume-culling-for-block-percentage
+   (maybe-non-negative-integer 5)
+   "Start culling when available blocks drop below this percentage."
+   (serializer (make-percentage-threshold-serializer 'bcull)))
+
+  (resume-culling-for-file-percentage
+   (maybe-non-negative-integer 5)
+   "Start culling when available files drop below this percentage."
+   (serializer (make-percentage-threshold-serializer 'fcull)))
+
+  (pause-caching-for-block-percentage
+   (maybe-non-negative-integer 1)
+   "Pause further allocations when available blocks drop below this percentage."
+   (serializer (make-percentage-threshold-serializer 'bstop)))
+
+  (pause-caching-for-file-percentage
+   (maybe-non-negative-integer 1)
+   "Pause further allocations when available files drop below this percentage."
+   (serializer (make-percentage-threshold-serializer 'fstop)))
+
+  ;; run time optimizations in the configuration file
+  (log2-table-size
+   (maybe-non-negative-integer 12)
+   "Size of tables holding cullable objects in logarithm of base 2."
+   (serializer (make-option-serializer 'culltable)))
+
+  (cull?
+   (boolean #t)
+   "Create free space by culling (consumes system load)."
+   (serializer
+    (lambda (variable-symbol value)
+      (if value "" "nocull\n"))))
+
+  ;; kernel module debugging in the configuration file
+  (trace-function-entry-in-kernel-module?
+   (boolean #f)
+   "Trace function entry in the kernel module (for debugging)."
+   (serializer empty-serializer))
+
+  (trace-function-exit-in-kernel-module?
+   (boolean #f)
+   "Trace function exit in the kernel module (for debugging)."
+   (serializer empty-serializer))
+
+  (trace-internal-checkpoints-in-kernel-module?
+   (boolean #f)
+   "Trace internal checkpoints in the kernel module (for debugging)."
+   (serializer empty-serializer)))
+
+(define (serialize-cachefilesd-configuration configuration)
+  (mixed-text-file
+   "cachefilesd.conf"
+   (serialize-configuration configuration cachefilesd-configuration-fields)))
+
+(define (cachefilesd-shepherd-service config)
+  "Return a list of <shepherd-service> for cachefilesd for CONFIG."
+  (match-record
+      config <cachefilesd-configuration> (cachefilesd
+                                          debug-output?
+                                          use-syslog?
+                                          scan?
+                                          cache-directory)
+      (let ((configuration-file (serialize-cachefilesd-configuration config)))
+        (shepherd-service
+         (documentation "Run the cachefilesd daemon for FS-Cache.")
+         (provision '(cachefilesd))
+         (requirement (append '(file-systems)
+                              (if use-syslog? '(syslogd) '())))
+         (start #~(begin
+                    (and=> #$(maybe-value cache-directory) mkdir-p)
+                    (make-forkexec-constructor
+                     `(#$(file-append cachefilesd "/sbin/cachefilesd")
+                       ;; do not detach
+                       "-n"
+                       #$@(if debug-output? '("-d") '())
+                       #$@(if use-syslog? '() '("-s"))
+                       #$@(if scan? '() '("-N"))
+                       "-f" #$configuration-file))))
+         (stop #~(make-kill-destructor))))))
+
+(define cachefilesd-service-type
+  (service-type
+   (name 'cachefilesd)
+   (description
+    "Run the FS-Cache backend daemon @command{cachefilesd}.")
+   (extensions
+    (list
+     (service-extension kernel-module-loader-service-type
+                        (const '("cachefiles")))
+     (service-extension shepherd-root-service-type
+                        (compose list cachefilesd-shepherd-service))))
+   (default-value (cachefilesd-configuration))))
+
 
 ;;;
 ;;; Reliability, Availability, and Serviceability (RAS) daemon
@@ -351,7 +548,7 @@ (define rasdaemon-service-type
 
 
 ;;;
-;;; Kernel module loader.
+;;; Zram device
 ;;;
 
 (define-record-type* <zram-device-configuration>
diff --git a/gnu/tests/cachefilesd.scm b/gnu/tests/cachefilesd.scm
new file mode 100644
index 0000000000..7f5d513067
--- /dev/null
+++ b/gnu/tests/cachefilesd.scm
@@ -0,0 +1,71 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2017 Peter Mikkelsen <petermikkelsen10 <at> gmail.com>
+;;; Copyright © 2022 Bruno Victal <mirai <at> makinata.eu>
+;;; Copyright © 2023 Felix Lechner <felix.lechner <at> lease-up.com>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (gnu tests cachefilesd)
+  #:use-module (gnu tests)
+  #:use-module (gnu system)
+  #:use-module (gnu system vm)
+  #:use-module (gnu services)
+  #:use-module (gnu services linux)
+  #:use-module (guix gexp)
+  #:export (%test-cachefilesd))
+
+(define %cachefilesd-os
+  (simple-operating-system
+   (service cachefilesd-service-type
+            (cachefilesd-configuration
+             (cache-directory "/var/cache/fscache")))))
+
+(define (run-cachefilesd-test)
+  "Run tests in %cachefilesd-os, which has cachefilesd running."
+  (define os
+    (marionette-operating-system
+     %cachefilesd-os
+     #:imported-modules '((gnu services herd))))
+
+  (define vm
+    (virtual-machine os))
+
+  (define test
+    (with-imported-modules '((gnu build marionette))
+      #~(begin
+          (use-modules (srfi srfi-64)
+                       (gnu build marionette))
+          (define marionette
+            (make-marionette (list #$vm)))
+
+          (test-runner-current (system-test-runner #$output))
+          (test-begin "cachefilesd")
+
+          (test-assert "service is running"
+            (marionette-eval
+             '(begin
+                (use-modules (gnu services herd))
+                (start-service 'cachefilesd))
+             marionette))
+
+          (test-end))))
+  (gexp->derivation "cachefilesd-test" test))
+
+(define %test-cachefilesd
+  (system-test
+   (name "cachefilesd")
+   (description "Test that the cachefilesd runs when started.")
+   (value (run-cachefilesd-test))))

base-commit: d64d6ea2cf5a1be801be355031fb2cfa5901a92a
-- 
2.40.1

Message #25 received at 63182-done <at> debbugs.gnu.org (full text, mbox):

From: Ludovic Courtès <ludo <at> gnu.org>
To: Felix Lechner <felix.lechner <at> lease-up.com>
Cc: 63182-done <at> debbugs.gnu.org, Bruno Victal <mirai <at> makinata.eu>
Subject: Re: bug#63182: [PATCH 0/1] Add cachefilesd service
Date: Tue, 15 Aug 2023 22:40:01 +0200

Hi,

Felix Lechner <felix.lechner <at> lease-up.com> skribis:

> Thanks to Bruno Victal "mirai" for cooperating on this patch and for
> generously sharing a wealth of insights about Guix services.
>
> Thanks to Jean-Baptiste Note for an early version of this service!
>
> Co-authored-by: Bruno Victal <mirai <at> makinata.eu>

Applied with small edits to ‘guix.texi’ and a commit log that follows
our conventions.

Thanks to the two of you!

Ludo’.

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