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authorHartmut Goebel <h.goebel@crazy-compilers.com>2017-10-25 18:13:15 +0200
committerHartmut Goebel <h.goebel@crazy-compilers.com>2017-11-08 18:23:05 +0100
commitc8289690365887ca1dd122645e479a89cf7cd969 (patch)
treea02e832d8f823061a916db682f4b0359e3d1f23b /gnu/build
parent34260a10d70c4eae87fc48419b7134fbbb4bbd30 (diff)
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".
Diffstat (limited to 'gnu/build')
-rw-r--r--gnu/build/linux-boot.scm43
1 files changed, 13 insertions, 30 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 @@ the last argument of `mknod'."
(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 @@ UNIONFS."
(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)))