[PATCH 2/2] system: Add btrfs file system support.

[David Craven <david@craven.ch>]

* gnu/system/linux-initrd.scm (linux-modules, helper-packages): Add
  btrfs modules when a btrfs file-system is used.
* gnu/build/file-systems.scm (check-file-system-irrecoverable-error,
  check-file-system-ext): New variables.
  (check-file-system): Support non ext file systems gracefully.
---
 gnu/build/file-systems.scm  | 30 ++++++++++++++++++++----------
 gnu/system/linux-initrd.scm | 10 +++++++---
 2 files changed, 27 insertions(+), 13 deletions(-)

diff --git a/gnu/build/file-systems.scm b/gnu/build/file-systems.scm
index 431b287..9f57ee5 100644
--- a/gnu/build/file-systems.scm
+++ b/gnu/build/file-systems.scm
@@ -410,12 +410,15 @@ the following:
     (else
      (error "unknown device title" title))))
 
-(define (check-file-system device type)
-  "Run a file system check of TYPE on DEVICE."
-  (define fsck
-    (string-append "fsck." type))
-
-  (let ((status (system* fsck "-v" "-p" "-C" "0" device)))
+(define (check-file-system-irrecoverable-error prog code device)
+  (format (current-error-port)
+          "'~a' exited with code ~a on ~a; spawning Bourne-like REPL~%"
+          prog code device)
+  (start-repl %bournish-language))
+
+(define (check-file-system-ext device type)
+  (let* ((fsck (string-append "fsck." type))
+         (status (system* fsck "-v" "-p" "-C" "0" device)))
     (match (status:exit-val status)
       (0
        #t)
@@ -428,10 +431,17 @@ the following:
        (sleep 3)
        (reboot))
       (code
-       (format (current-error-port) "'~a' exited with code ~a on ~a; \
-spawning Bourne-like REPL~%"
-               fsck code device)
-       (start-repl %bournish-language)))))
+       (check-file-system-irrecoverable-error fsck code device)))))
+
+(define (check-file-system device type)
+  "Run a file system check of TYPE on DEVICE."
+    (cond
+     ((string-prefix? "ext" type)
+      (check-file-system-ext device type))
+     ((string-prefix? "btrfs" type)
+      (zero? (system* "btrfs" "device" "scan")))
+     (#t (format (current-error-port)
+                 "Don't know how to check '~a' file systems; skipping~%" type))))
 
 (define (mount-flags->bit-mask flags)
   "Return the number suitable for the 'flags' argument of 'mount' that
diff --git a/gnu/system/linux-initrd.scm b/gnu/system/linux-initrd.scm
index 174239a..de8b785 100644
--- a/gnu/system/linux-initrd.scm
+++ b/gnu/system/linux-initrd.scm
@@ -193,6 +193,9 @@ loaded at boot time in the order in which they appear."
       ,@(if (find (file-system-type-predicate "9p") file-systems)
             virtio-9p-modules
             '())
+      ,@(if (find (file-system-type-predicate "btrfs") file-systems)
+            '("btrfs")
+            '())
       ,@(if volatile-root?
             '("fuse")
             '())
@@ -200,11 +203,12 @@ loaded at boot time in the order in which they appear."
 
   (define helper-packages
     ;; Packages to be copied on the initrd.
-    `(,@(if (find (lambda (fs)
-                    (string-prefix? "ext" (file-system-type fs)))
-                  file-systems)
+    `(,@(if (find (file-system-type-predicate "ext4") file-systems)
             (list e2fsck/static)
             '())
+      ,@(if (find (file-system-type-predicate "btrfs") file-systems)
+            (list btrfs-progs/static)
+            '())
       ,@(if volatile-root?
             (list unionfs-fuse/static)
             '())))
-- 
2.9.0