From c8289690365887ca1dd122645e479a89cf7cd969 Mon Sep 17 00:00:00 2001 From: Hartmut Goebel <h.goebel@crazy-compilers.com> Date: Wed, 25 Oct 2017 18:13:15 +0200 Subject: build: Use overlayfs instead of unionfs. Overlayfs is part of the kernel, while unionfs needs FUSE. This also reduces the size of the initrd by ca. 4.3% (487K). * gnu/build/linux-boot.scm (mount-root-file-system): Remove optional parameter "unionfs"; mount using overlayfs instead of unionfs; new directory layout requied by overlayfs; update documentation. [mark-as-not-killable]: Remove now unused function * gnu/system/linux-initrd.scm (file-system-packages): Remove now unused packages "unionfs-fuse/static" and thus unused related 'if'. (linux-modules): Replace "fuse" by "overlay". --- gnu/build/linux-boot.scm | 43 +++++++++++++------------------------------ gnu/system/linux-initrd.scm | 5 +---- 2 files changed, 14 insertions(+), 34 deletions(-) diff --git a/gnu/build/linux-boot.scm b/gnu/build/linux-boot.scm index 3712abe910..a1ff4dd1ea 100644 --- a/gnu/build/linux-boot.scm +++ b/gnu/build/linux-boot.scm @@ -241,20 +241,10 @@ (define (pidof program) (filter-map string->number (scandir "/proc"))))) (define* (mount-root-file-system root type - #:key volatile-root? (unionfs "unionfs")) + #:key volatile-root?) "Mount the root file system of type TYPE at device ROOT. If VOLATILE-ROOT? -is true, mount ROOT read-only and make it a union with a writable tmpfs using -UNIONFS." - (define (mark-as-not-killable pid) - ;; Tell the 'user-processes' shepherd service that PID must be kept alive - ;; when shutting down. - (mkdir-p "/root/etc/shepherd") - (let ((port (open-file "/root/etc/shepherd/do-not-kill" "a"))) - (chmod port #o600) - (write pid port) - (newline port) - (close-port port))) - +is true, mount ROOT read-only and make it a overlay with a writable tmpfs +using the kernel build-in overlayfs." (if volatile-root? (begin (mkdir-p "/real-root") @@ -262,24 +252,17 @@ (define (mark-as-not-killable pid) (mkdir-p "/rw-root") (mount "none" "/rw-root" "tmpfs") + ;; Create the upperdir and the workdir of the overlayfs + (mkdir-p "/rw-root/upper") + (mkdir-p "/rw-root/work") + ;; We want read-write /dev nodes. - (mkdir-p "/rw-root/dev") - (mount "none" "/rw-root/dev" "devtmpfs") - - ;; Make /root a union of the tmpfs and the actual root. Use - ;; 'max_files' to set a high RLIMIT_NOFILE for the unionfs process - ;; itself. Failing to do that, we quickly run out of file - ;; descriptors; see <http://bugs.gnu.org/17827>. - (unless (zero? (system* unionfs "-o" - "cow,allow_other,use_ino,suid,dev,max_files=65536" - "/rw-root=RW:/real-root=RO" - "/root")) - (error "unionfs failed")) - - ;; Make sure unionfs remains alive till the end. Because - ;; 'fuse_daemonize' doesn't tell the PID of the forked daemon, we - ;; have to resort to 'pidof' here. - (mark-as-not-killable (pidof unionfs))) + (mkdir-p "/rw-root/upper/dev") + (mount "none" "/rw-root/upper/dev" "devtmpfs") + + ;; Make /root an overlay of the tmpfs and the actual root. + (mount "none" "/root" "overlay" 0 + "lowerdir=/real-root,upperdir=/rw-root/upper,workdir=/rw-root/work")) (begin (check-file-system root type) (mount root "/root" type))) diff --git a/gnu/system/linux-initrd.scm b/gnu/system/linux-initrd.scm index 948c543a15..b592defa45 100644 --- a/gnu/system/linux-initrd.scm +++ b/gnu/system/linux-initrd.scm @@ -234,9 +234,6 @@ (define* (file-system-packages file-systems #:key (volatile-root? #f)) '()) ,@(if (find (file-system-type-predicate "btrfs") file-systems) (list btrfs-progs/static) - '()) - ,@(if volatile-root? - (list unionfs-fuse/static) '()))) (define* (base-initrd file-systems @@ -308,7 +305,7 @@ (define linux-modules '("isofs") '()) ,@(if volatile-root? - '("fuse") + '("overlay") '()) ,@extra-modules)) -- cgit v1.2.3