file-systems: Add a 'mount?' field.

Fixes <http://bugs.gnu.org/22176>.
Reported by Florian Paul Schmidt <mista.tapas@gmx.net>.

* gnu/system/file-systems.scm (<file-system>)[mount?]: New field.
(file-system->spec): Adjust accordingly.
* gnu/services/base.scm (file-system-dmd-service): Return the empty list
when FILE-SYSTEM has 'mount?' set to false.
(user-processes-service): Select the subset of FILE-SYSTEMS that matches
'file-system-mount?'.
* doc/guix.texi (File Systems): Document it.

1 files changed, 4 insertions, 1 deletions

diff --git a/gnu/system/file-systems.scm b/gnu/system/file-systems.scm
index 0a4b385fe33..47a3dbc1e8b 100644
--- a/gnu/system/file-systems.scm
+++ b/gnu/system/file-systems.scm
@@ -35,6 +35,7 @@
             file-system-needed-for-boot?
             file-system-flags
             file-system-options
+            file-system-mount?
             file-system-check?
             file-system-create-mount-point?
             file-system-dependencies
@@ -93,6 +94,8 @@
                     (default '()))
   (options          file-system-options           ; string or #f
                     (default #f))
+  (mount?           file-system-mount?            ; Boolean
+                    (default #t))
   (needed-for-boot? %file-system-needed-for-boot? ; Boolean
                     (default #f))
   (check?           file-system-check?            ; Boolean
@@ -112,7 +115,7 @@ file system."
   "Return a list corresponding to file-system FS that can be passed to the
 initrd code."
   (match fs
-    (($ <file-system> device title mount-point type flags options _ check?)
+    (($ <file-system> device title mount-point type flags options _ _ check?)
      (list device title mount-point type flags options check?))))
 
 (define %uuid-rx