diff options
Diffstat (limited to 'gnu/system/install.scm')
| -rw-r--r-- | gnu/system/install.scm | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/gnu/system/install.scm b/gnu/system/install.scm index d4a32609ba..d3539b3f84 100644 --- a/gnu/system/install.scm +++ b/gnu/system/install.scm @@ -20,6 +20,7 @@ #:use-module (gnu) #:use-module (guix gexp) #:use-module (guix monads) + #:use-module ((guix store) #:select (%store-prefix)) #:use-module (gnu packages linux) #:use-module (gnu packages package-management) #:use-module (gnu packages disk) @@ -42,6 +43,78 @@ manual." "-f" (string-append #$guix "/share/info/guix.info") "-n" "System Installation"))) +(define %backing-directory + ;; Sub-directory used as the backing store for copy-on-write. + "/tmp/guix-inst") + +(define (make-cow-store target) + "Return a gexp that makes the store copy-on-write, using TARGET as the +backing store. This is useful when TARGET is on a hard disk, whereas the +current store is on a RAM disk." + (define (unionfs read-only read-write mount-point) + ;; Make MOUNT-POINT the union of READ-ONLY and READ-WRITE. + + ;; Note: in the command below, READ-WRITE appears before READ-ONLY so that + ;; it is considered a "higher-level branch", as per unionfs-fuse(8), + ;; thereby allowing files existing on READ-ONLY to be copied over to + ;; READ-WRITE. + #~(fork+exec-command + (list (string-append #$unionfs-fuse "/bin/unionfs") + "-o" + "cow,allow_other,use_ino,max_files=65536,nonempty" + (string-append #$read-write "=RW:" #$read-only "=RO") + #$mount-point))) + + (define (set-store-permissions directory) + ;; Set the right perms on DIRECTORY to use it as the store. + #~(begin + (chown #$directory 0 30000) ;use the fixed 'guixbuild' GID + (chmod #$directory #o1775))) + + #~(begin + (unless (file-exists? "/.ro-store") + (mkdir "/.ro-store") + (mount #$(%store-prefix) "/.ro-store" "none" + (logior MS_BIND MS_RDONLY))) + + (let ((rw-dir (string-append target #$%backing-directory))) + (mkdir-p rw-dir) + (mkdir-p "/.rw-store") + #$(set-store-permissions #~rw-dir) + #$(set-store-permissions "/.rw-store") + + ;; Mount the union, then atomically make it the store. + (and #$(unionfs "/.ro-store" #~rw-dir "/.rw-store") + (begin + (sleep 1) ;XXX: wait for unionfs to be ready + (mount "/.rw-store" #$(%store-prefix) "" MS_MOVE) + (rmdir "/.rw-store")))))) + +(define (cow-store-service) + "Return a service that makes the store copy-on-write, such that writes go to +the user's target storage device rather than on the RAM disk." + ;; See <http://bugs.gnu.org/18061> for the initial report. + (with-monad %store-monad + (return (service + (requirement '(root-file-system user-processes)) + (provision '(cow-store)) + (documentation + "Make the store copy-on-write, with writes going to \ +the given target.") + (start #~(case-lambda + ((target) + #$(make-cow-store #~target) + target) + (else + ;; Do nothing, and mark the service as stopped. + #f))) + (stop #~(lambda (target) + ;; Delete the temporary directory, but leave everything + ;; mounted as there may still be processes using it + ;; since 'user-processes' doesn't depend on us. + (delete-file-recursively + (string-append target #$%backing-directory)))))))) + (define (installation-services) "Return the list services for the installation image." (let ((motd (text-file "motd" " @@ -88,6 +161,10 @@ You have been warned. Thanks for being so brave. ;; Start udev so that useful device nodes are available. (udev-service) + ;; Add the 'cow-store' service, which users have to start manually + ;; since it takes the installation directory as an argument. + (cow-store-service) + ;; Install Unicode support and a suitable font. (console-font-service "tty1") (console-font-service "tty2") |