From d9565f7d8797d6ab826776c9ac3befdf20f73e05 Mon Sep 17 00:00:00 2001 From: Hartmut Goebel Date: Fri, 27 Oct 2017 15:33:38 +0200 Subject: [PATCH] install: Use overlayfs instead of unionfs. I dediced to keep adding /tmp as tmpfs since I was not able to trigger bug while still using unionfs, so I could not verify whether this mount is still needed with overlayfs. Mapping /tmp to tmpfs does not harm, so we are on the save side. * gnu/system/install.scm (make-cow-store): Mount /gnu/store without additional read-only bind-mount, since in overlayfs the "lower" level is always read-only. Add work-dir required by overlayfs. No need to sleep anymore since now using the mount syscall. [unionfs]: Remove now unused function. (%installation-services): Update comment. (installation-os)[file-systems]: Update comment. --- gnu/system/install.scm | 47 +++++++++++++++--------------------------- 1 file changed, 17 insertions(+), 30 deletions(-) diff --git a/gnu/system/install.scm b/gnu/system/install.scm index eb362f91a8..f86410f522 100644 --- a/gnu/system/install.scm +++ b/gnu/system/install.scm @@ -71,19 +71,6 @@ manual." "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. @@ -97,23 +84,21 @@ current store is on a RAM disk." (mkdir-p tmpdir) (mount tmpdir "/tmp" "none" MS_BIND)) - (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))) + (let* ((rw-dir (string-append target #$%backing-directory)) + (work-dir (string-append rw-dir "/../.overlayfs-workdir"))) (mkdir-p rw-dir) + (mkdir-p work-dir) (mkdir-p "/.rw-store") #$(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" #$(%store-prefix) "" MS_MOVE) - (rmdir "/.rw-store")))))) + ;; Mount the overlay, then atomically make it the store. + (mount "none" "/.rw-store" "overlay" 0 + (string-append "lowerdir=" #$(%store-prefix) "," + "upperdir=" rw-dir "," + "workdir=" work-dir)) + (mount "/.rw-store" #$(%store-prefix) "" MS_MOVE) + (rmdir "/.rw-store")))) (define cow-store-service-type (shepherd-service-type @@ -278,7 +263,7 @@ You have been warned. Thanks for being so brave. (allow-empty-passwords? #f) (password-authentication? #t))) - ;; Since this is running on a USB stick with a unionfs as the root + ;; Since this is running on a USB stick with a overlayfs as the root ;; file system, use an appropriate cache configuration. (nscd-service (nscd-configuration (caches %nscd-minimal-caches))) @@ -317,10 +302,12 @@ Use Alt-F2 for documentation. (title 'label) (type "ext4")) - ;; Make /tmp a tmpfs instead of keeping the unionfs. This is - ;; because FUSE creates '.fuse_hiddenXYZ' files for each open file, - ;; and this confuses Guix's test suite, for instance. See - ;; . + ;; Make /tmp a tmpfs instead of keeping the overlayfs. This + ;; originally was used for unionfs because FUSE creates + ;; '.fuse_hiddenXYZ' files for each open file, and this confuses + ;; Guix's test suite, for instance (see + ;; ). We keep this for overlayfs to be + ;; on the save side. (file-system (mount-point "/tmp") (device "none")