[PATCH] gnu: Mark /gnu/store as needed for boot.

[John Darrington <jmd@gnu.org>]

* gnu/system/file-systems.scm (all-subpaths): New procedure.
(file-system-needed-for-boot?): Use it to check for ancestors
of %store-directory.
---
 gnu/system/file-systems.scm | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/gnu/system/file-systems.scm b/gnu/system/file-systems.scm
index 4cc1221..d42f271 100644
--- a/gnu/system/file-systems.scm
+++ b/gnu/system/file-systems.scm
@@ -20,6 +20,7 @@
   #:use-module (ice-9 match)
   #:use-module (guix records)
   #:use-module (guix store)
+  #:use-module (guix build utils)
   #:use-module ((gnu build file-systems)
                 #:select (string->uuid uuid->string))
   #:re-export (string->uuid
@@ -95,11 +96,29 @@
   (dependencies     file-system-dependencies      ; list of <file-system>
                     (default '())))               ; or <mapped-device>
 
+
+(define (all-subpaths path)
+  "Given a directory PATH return a list of all paths which
+are ancestors of this path, including PATH itself"
+ (let loop ((path (string-split path #\/))
+	    (ac '()))
+   (if (null? path)
+       ac
+       (loop (cdr path)
+	     (cons
+	      (string-append
+	       (match ac
+		 (()  "/")
+		 ((x _ . _) (string-append x "/"))
+		 ((x . _) x))
+	       (car path))
+	      ac)))))
+
 (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=? "/" (file-system-mount-point fs))))
+      (member (file-system-mount-point fs) (all-subpaths (%store-directory)))))
 
 (define (file-system->spec fs)
   "Return a list corresponding to file-system FS that can be passed to the
-- 
2.1.4