Adds missing newline

* Adds missing newline:
  "\n" was missing.

Makefile

@@ -1,14 +1,71 @@
 PKGNAME ?= grub-btrfs
 PREFIX ?= /usr
 
+INITCPIO ?= false
+
 SHARE_DIR = $(DESTDIR)$(PREFIX)/share
 LIB_DIR = $(DESTDIR)$(PREFIX)/lib
 
-.PHONY: install
+.PHONY: install uninstall help
 
 install:
+	@if test "$(shell id -u)" != 0; then \
+		echo "You are not root, run this target as root please."; \
+		exit 1; \
+	fi
 	@install -Dm755 -t "$(DESTDIR)/etc/grub.d/" 41_snapshots-btrfs
 	@install -Dm644 -t "$(DESTDIR)/etc/default/grub-btrfs/" config
 	@install -Dm644 -t "$(LIB_DIR)/systemd/system/" grub-btrfs.service
 	@install -Dm644 -t "$(LIB_DIR)/systemd/system/" grub-btrfs.path
 	@install -Dm644 -t "$(SHARE_DIR)/licenses/$(PKGNAME)/" LICENSE
+	@# Arch Linux like distros only :
+	@if test "$(INITCPIO)" = true; then \
+		install -Dm644 "initramfs/Arch Linux/overlay_snap_ro-install" "$(LIB_DIR)/initcpio/install/grub-btrfs-overlayfs"; \
+		install -Dm644 "initramfs/Arch Linux/overlay_snap_ro-hook" "$(LIB_DIR)/initcpio/hooks/grub-btrfs-overlayfs"; \
+	 fi
+	@install -Dm644 -t "$(SHARE_DIR)/doc/$(PKGNAME)/" README.md
+	@install -Dm644 "initramfs/readme.md" "$(SHARE_DIR)/doc/$(PKGNAME)/initramfs-overlayfs.md"
+
+uninstall:
+	@if test "$(shell id -u)" != 0; then \
+		echo "You are not root, run this target as root please."; \
+		exit 1; \
+	fi
+	@grub_dirname="$$(grep -oP '^[[:space:]]*GRUB_BTRFS_GRUB_DIRNAME=\K.*' "$(DESTDIR)/etc/default/grub-btrfs/config" | sed "s|\s*#.*||;s|(\s*\(.\+\)\s*)|\1|;s|['\"]||g")"; \
+	 rm -f "$${grub_dirname:-/boot/grub}/grub-btrfs.cfg"
+	@rm -f "$(DESTDIR)/etc/default/grub-btrfs/config"
+	@rm -f "$(DESTDIR)/etc/grub.d/41_snapshots-btrfs"
+	@rm -f "$(LIB_DIR)/systemd/system/grub-btrfs.service"
+	@rm -f "$(LIB_DIR)/systemd/system/grub-btrfs.path"
+	@rm -f "$(LIB_DIR)/initcpio/install/grub-btrfs-overlayfs"
+	@rm -f "$(LIB_DIR)/initcpio/hooks/grub-btrfs-overlayfs"
+	@# Arch Linux UNlike distros only :
+	@if test "$(INITCPIO)" != true && test -d "$(LIB_DIR)/initcpio"; then \
+		rmdir --ignore-fail-on-non-empty "$(LIB_DIR)/initcpio/install" || :; \
+		rmdir --ignore-fail-on-non-empty "$(LIB_DIR)/initcpio/hooks" || :; \
+		rmdir --ignore-fail-on-non-empty "$(LIB_DIR)/initcpio" || :; \
+	 fi
+	@rm -f "$(SHARE_DIR)/doc/$(PKGNAME)/README.md"
+	@rm -f "$(SHARE_DIR)/doc/$(PKGNAME)/initramfs-overlayfs.md"
+	@rm -f "$(SHARE_DIR)/licenses/$(PKGNAME)/LICENSE"
+	@rmdir --ignore-fail-on-non-empty "$(SHARE_DIR)/doc/$(PKGNAME)/" || :
+	@rmdir --ignore-fail-on-non-empty "$(SHARE_DIR)/licenses/$(PKGNAME)/" || :
+	@rmdir --ignore-fail-on-non-empty "$(DESTDIR)/etc/default/grub-btrfs" || :
+
+help:
+	@echo
+	@echo "Usage: $(MAKE) [ <parameter>=<value> ... ] [ <action> ]"
+	@echo
+	@echo "  actions: install"
+	@echo "           uninstall"
+	@echo "           help"
+	@echo
+	@echo "  parameter | type | description                    | defaults"
+	@echo "  ----------+------+--------------------------------+----------------------------"
+	@echo "  DESTDIR   | path | install destination            | <unset>"
+	@echo "  PREFIX    | path | system tree prefix             | '/usr'"
+	@echo "  SHARE_DIR | path | shared data location           | '\$$(DESTDIR)\$$(PREFIX)/share'"
+	@echo "  LIB_DIR   | path | system libraries location      | '\$$(DESTDIR)\$$(PREFIX)/lib'"
+	@echo "  PKGNAME   | name | name of the ditributed package | 'grub-btrfs'"
+	@echo "  INITCPIO  | bool | include mkinitcpio hook        | false"
+	@echo

README.md

@@ -6,164 +6,100 @@
 This is a version 4.xx of grub-btrfs
 ##### BTC donation address: `1Lbvz244WA8xbpHek9W2Y12cakM6rDe5Rt`
 ##
-### Description
+### Description :
 Improves Grub by adding "btrfs snapshots" to the Grub menu.
 
-You can start your system on a "snapshot" from the Grub menu.
-
+You can boot your system on a "snapshot" from the Grub menu.  
 Supports manual snapshots, snapper, timeshift ...
 
 ##### Warning: booting on read-only snapshots can be tricky
 
-If you choose to do it, `/var/log` must be on a separate subvolume.
-
-Otherwise, make sure your snapshots are writeable.
-
+If you choose to do it, `/var/log` or even `/var` must be on a separate subvolume.  
+Otherwise, make sure your snapshots are writeable.  
 See [this ticket](https://github.com/Antynea/grub-btrfs/issues/92) for more info.
 
+This project includes its own solution.  
+Refer to the [documentation](https://github.com/Antynea/grub-btrfs/blob/master/initramfs/readme.md).
+
+##
 ### What does grub-btrfs v4.xx do :
 * Automatically List snapshots existing on root partition (btrfs).
 * Automatically Detect if "/boot" is in separate partition.
-* Automatically Detect kernel, initramfs and intel microcode in "/boot" directory on snapshots.
+* Automatically Detect kernel, initramfs and intel/amd microcode in "/boot" directory on snapshots.
 * Automatically Create corresponding "menuentry" in `grub.cfg`
 * Automatically detect snapper and use snapper's snapshot description if available.
 * Automatically generate `grub.cfg` if you use the provided systemd service.
+
 ##
 ### Installation :
 #### Arch Linux
-
+The package is available in the community repository [grub-btrfs](https://archlinux.org/packages/community/any/grub-btrfs/)
 ```
 pacman -S grub-btrfs
 ```
 
-### Manual
+#### Manual
 
 * Run `make install` or look into Makefile for instructions on where to put each file.
+* Dependencies:
+  * [btrfs-progs](https://archlinux.org/packages/core/x86_64/btrfs-progs/)
+  * [grub](https://archlinux.org/packages/core/x86_64/grub/)
 
-NOTE: Generate your Grub menu after installation for the changes to take effect.
-
-On Arch Linux use `grub-mkconfig -o /boot/grub/grub.cfg`.
-
+NOTE: Generate your Grub menu after installation for the changes to take effect.  
+On Arch Linux use `grub-mkconfig -o /boot/grub/grub.cfg`.  
+On Debian-like distribution `update-grub` is an alias to `grub-mkconfig ...`
 ##
-### Customization:
+### Customization :
 
-You have the possibility to modify many parameters in `/etc/default/grub-btrfs/config`.
-
-* GRUB_BTRFS_SUBMENUNAME="Arch Linux Snapshots"
-
-	Name appearing in the Grub menu. Use distribution information from /etc/os-release by default.
-
-* GRUB_BTRFS_PREFIXENTRY="Snapshot:"
-
-	Add a name ahead your snapshots entries in the Grub menu.
-	
-* GRUB_BTRFS_DISPLAY_PATH_SNAPSHOT="true"
-	
-	Show full path snapshot or only name in the Grub menu, weird reaction with snapper.
-	
-* GRUB_BTRFS_TITLE_FORMAT="p/d/n"
-
- 	Custom title, shows/hides p"prefix" d"date" n"name" in the Grub menu, separator "/", custom order available.
-
-* GRUB_BTRFS_LIMIT="50"
-
-	Limit the number of snapshots populated in the GRUB menu.
-
-* GRUB_BTRFS_SUBVOLUME_SORT="descending"
-
-	Sort the found subvolumes by newest first ("descending") or oldest first ("ascending"). 
-	
-	If "ascending" is chosen then 
-	
-	the $GRUB_BTRFS_LIMIT oldest subvolumes will populate the menu.
-
-* GRUB_BTRFS_SHOW_SNAPSHOTS_FOUND="true"
-	
-	Show snapshots found during run "grub-mkconfig".
-	
-* GRUB_BTRFS_SHOW_TOTAL_SNAPSHOTS_FOUND="true"
-	
-	Show Total number of snapshots found during run "grub-mkconfig".
-
-* GRUB_BTRFS_NKERNEL=("kernel-custom")
-
-	Use it only if you have a custom kernel name
-
-* GRUB_BTRFS_NINIT=("initramfs-custom.img" "initrd.img-custom")
-
-	Use it only if you have a custom initramfs name.
-
-* GRUB_BTRFS_INTEL_UCODE=("intel-ucode.img")
-
-	Use it only if you have custom intel-ucode.
-
-* GRUB_BTRFS_IGNORE_SPECIFIC_PATH=("var/lib/docker")
-
-	Ignore specific path during run "grub-mkconfig".
-	
-	For example: 
-	
-	If path is a directory `# Found Snapshot: 2016-03-31 10:24:41` **var/lib/docker/btrfs/subvolumes/...**
-	
-	use : `GRUB_BTRFS_IGNORE_SPECIFIC_PATH=("var/lib/docker")`
-	
-	If path is a subvolume : `# Found Snapshot: 2016-03-31 10:24:41` **@var/lib/docker/btrfs/subvolumes/...**
-	
-	use : `GRUB_BTRFS_IGNORE_SPECIFIC_PATH=("@var/lib/docker")`
-	
-	You can combine them
-	
-	use : `GRUB_BTRFS_IGNORE_SPECIFIC_PATH=("@var/lib/docker" "var/lib/docker")`
-
-
-* GRUB_BTRFS_SNAPPER_CONFIG="root"													
-
-	Snapper's config name to use.
-
-* GRUB_BTRFS_DISABLE="false"
-
-	Disable grub-btrfs.
-
-* GRUB_BTRFS_DIRNAME="grub"
-
-	Name of the grub folder in `/boot/`, might be grub2 on some distributions.
-
-* GRUB_BTRFS_OVERRIDE_BOOT_PARTITION_DETECTION="false"
-
-	Change to "true" if you have a boot partition in a different subvolume.
-
-* GRUB_BTRFS_MKCONFIG=grub-mkconfig
-
-	Name or path of the 'grub-mkconfig' executable; might be 'grub2-mkconfig' on some distributions.
-	
-- Password protection management for submenu (refer to the [Grub documentation](https://www.gnu.org/software/grub/manual/grub/grub.html#Authentication-and-authorisation))
-
-	- GRUB_BTRFS_PROTECTION_AUTHORIZED_USERS=""
-
-		Add authorized usernames separate by comma (foo,bar)
-	
-		When Grub's password protection is enabled, the superuser is authorized by default, it isn't necessary to add it
-		
-	- GRUB_BTRFS_DISABLE_PROTECTION_SUBMENU="false"
-
-		Disable authentication support for submenu of Grub-btrfs only (--unrestricted)
-	
-		doesn't work if `GRUB_BTRFS_PROTECTION_AUTHORIZED_USERS` isn't empty
+You have the possibility to modify many parameters in `/etc/default/grub-btrfs/config`.  
+See [config file](https://github.com/Antynea/grub-btrfs/blob/master/config) for more information.
 
 ##
 ### Automatically update grub
-If you would like Grub to automatically update when a snapshot is made or deleted:
-* Mount your subvolume which contains snapshots to `/.snapshots`
-* Use `systemctl start/enable grub-btrfs.path`
-* `grub-btrfs.path` automatically (re)generates `grub.cfg` when a modification appears in `/.snapshots`
+1- If you would like grub-btrfs menu to automatically update when a snapshot is created or deleted:
+* Use `systemctl enable grub-btrfs.path`.
+  * `grub-btrfs.path` automatically (re)generates `grub-btrfs.cfg` when a modification appears in `/.snapshots` mount point (by default).
+  * If the `/.snapshots` mount point is already mounted, then use `systemctl start grub-btrfs.path` to start monitoring.  
+    Otherwise, the unit will automatically start monitoring when the mount point will be available.
+* If your snapshots location aren't mounted in `/.snapshots`, you must modify `grub-btrfs.path` unit using  
+`systemctl edit --full grub-btrfs.path` and run `systemctl reenable grub-btrfs.path` for changes take effect.  
+To find out the name of the `.mount` unit  
+use `systemctl list-units -t mount`.  
+	* For example: Timeshift mounts its snapshot folder in `/run/timeshift/backup/timeshift-btrfs/snapshots`.
+
+		Use `systemctl edit --full grub-btrfs.path`.
+		Then replace the whole block by:
+		```
+		[Unit]
+		Description=Monitors for new snapshots
+		DefaultDependencies=no
+		Requires=run-timeshift-backup.mount
+		After=run-timeshift-backup.mount
+		BindsTo=run-timeshift-backup.mount
+
+		[Path]
+		PathModified=/run/timeshift/backup/timeshift-btrfs/snapshots
+
+		[Install]
+		WantedBy=run-timeshift-backup.mount
+		```
+		Then save and finally run `systemctl reenable grub-btrfs.path` for changes take effect.  
+		Optional:  
+		If the `/run/timeshift/backup/timeshift-btrfs/snapshots` mount point is already mounted,  
+		then use `systemctl start grub-btrfs.path` to start monitoring.  
+		Otherwise, the unit will automatically start monitoring when the mount point will be available.  
+	* You can view your change to `systemctl cat grub-btrfs.path`.
+	* To revert change use `systemctl revert grub-btrfs.path`.
+
+2- If you would like grub-btrfs menu to automatically update on system restart/shutdown:  
+[Look at this comment](https://github.com/Antynea/grub-btrfs/issues/138#issuecomment-766918328)  
+Currently not implemented  
+##### Warning :
+by default, `grub-mkconfig` command is used.  
+Might be `grub2-mkconfig` on some systems (Fedora ...).   
+Edit `GRUB_BTRFS_MKCONFIG` variable in `/etc/default/grub-btrfs/config` file to reflect this.
 ##
 ### Special thanks for assistance and contributions
 * [maximbaz](https://github.com/maximbaz)
-* [crossroads1112](https://github.com/crossroads1112)
-* [penetal](https://github.com/penetal)
-* [wesbarnett](https://github.com/wesbarnett)
-* [Psykar](https://github.com/Psykar)
-* [anyc](https://github.com/anyc)
-* [daftaupe](https://github.com/daftaupe)
-* [N-Parsons](https://github.com/N-Parsons)
+* [All contributors](https://github.com/Antynea/grub-btrfs/graphs/contributors)
 ##

config

@@ -1,87 +1,131 @@
 #!/usr/bin/env bash
 
-# Name appearing in the Grub menu
-# Default: Use distribution information from /etc/os-release
+# Disable grub-btrfs.
+# Default: "false"
+#GRUB_BTRFS_DISABLE="true"
+
+# Name appearing in the Grub menu.
+# Default: "Use distribution information from /etc/os-release."
 #GRUB_BTRFS_SUBMENUNAME="Arch Linux snapshots"
 
-# Add a name ahead your snapshots entries in the Grub menu
+# Add a name ahead your snapshots entries in the Grub menu.
 # Default: "Snapshot:"
 #GRUB_BTRFS_PREFIXENTRY="Snapshot:"
 
-# Show full path snapshot or only name in the Grub menu
+# Show full path snapshot or only name in the Grub menu, weird reaction with snapper.
 # Default: "true"
-#GRUB_BTRFS_DISPLAY_PATH_SNAPSHOT="true"
+#GRUB_BTRFS_DISPLAY_PATH_SNAPSHOT="false"
 
-# Custom title
-# shows/hides p"prefix" d"date" n"name" in the Grub menu, separator "/", custom order available
+# Custom title.
+# shows/hides p"prefix" d"date" n"name" in the Grub menu, separator "/", custom order available.
 # Default: "p/d/n"
 #GRUB_BTRFS_TITLE_FORMAT="p/d/n"
 
-# Limit the number of snapshots populated in the GRUB menu
+# Limit the number of snapshots populated in the GRUB menu.
 # Default: "50"
 #GRUB_BTRFS_LIMIT="50"
 
-# Sort the found subvolumes by newest first ("descending") or oldest first ("ascending") and show $GRUB_BTRFS_LIMIT first entries.
-# Default: "descending"
-#GRUB_BTRFS_SUBVOLUME_SORT="descending"
+# Sort the found subvolumes by "ogeneration" or "generation" or "path" or "rootid".
+# # See Sorting section to https://btrfs.wiki.kernel.org/index.php/Manpage/btrfs-subvolume#SUBCOMMAND
+# "-rootid" means list snapshot by new ones first.
+# Default: "-rootid"
+#GRUB_BTRFS_SUBVOLUME_SORT="+ogen,-gen,path,rootid"
 
 # Show snapshots found during run "grub-mkconfig"
 # Default: "true"
-#GRUB_BTRFS_SHOW_SNAPSHOTS_FOUND="true"
+#GRUB_BTRFS_SHOW_SNAPSHOTS_FOUND="false"
 
 # Show Total of snapshots found during run "grub-mkconfig"
 # Default: "true"
 #GRUB_BTRFS_SHOW_TOTAL_SNAPSHOTS_FOUND="true"
 
-# Use only if you have custom kernel name
-# Default:
-#GRUB_BTRFS_NKERNEL=("vmlinuz-linux")
+# By default, "grub-btrfs" automatically detects most existing kernels.
+# If you have one or more custom kernels, you can add them here.
+# Default: ("")
+#GRUB_BTRFS_NKERNEL=("kernel-custom" "vmlinux-custom")
 
-# Use only if you have custom initramfs name
-# Default:
-#GRUB_BTRFS_NINIT=("initramfs-linux.img" "initramfs-linux-fallback.img")
+# By default, "grub-btrfs" automatically detects most existing initramfs.
+# If you have one or more custom initramfs, you can add them here.
+# Default: ("")
+#GRUB_BTRFS_NINIT=("initramfs-custom.img" "initrd-custom.img" "otherinit-custom.gz")
 
-# Use only if you have custom intel-ucode
-# Default:
-#GRUB_BTRFS_INTEL_UCODE=("intel-ucode.img")
+# By default, "grub-btrfs" automatically detects most existing microcodes.
+# If you have one or more custom microcodes, you can add them here.
+# Default: ("")
+#GRUB_BTRFS_CUSTOM_MICROCODE=("custom-ucode.img" "custom-uc.img "custom_ucode.cpio")
+
+# Comma seperated mount options to be used when booting a snapshot.
+# They can be defined here as well as in the "/" line inside the respective snapshots'
+# "/etc/fstab" files.  Mount options found in both places are combined, and this variable
+# takes priority over `fstab` entries.
+# NB: Do NOT include "subvol=..." or "subvolid=..." here.
+# Default: ""
+#GRUB_BTRFS_ROOTFLAGS="space_cache,commit=10,norecovery"
 
 # Ignore specific path during run "grub-mkconfig".
-# If path is a directory, # Found Snapshot: 2016-03-31 10:24:41 var/lib/docker/btrfs/subvolumes/...
-# use : GRUB_BTRFS_IGNORE_SPECIFIC_PATH=("var/lib/docker");
-# If path is a subvolume, # Found Snapshot: 2016-03-31 10:24:41 @var/lib/docker/btrfs/subvolumes/...
-# use : GRUB_BTRFS_IGNORE_SPECIFIC_PATH=("@var/lib/docker");
-# You can combine them
-# use : GRUB_BTRFS_IGNORE_SPECIFIC_PATH=("@var/lib/docker" "var/lib/docker")
-# Default: 
-GRUB_BTRFS_IGNORE_SPECIFIC_PATH=("@" "var/lib/docker" "@var/lib/docker")
+# Only exact paths are ignored.
+# e.g : if `specific path` = @, only `@` snapshot will be ignored.
+# Default: ("@")
+GRUB_BTRFS_IGNORE_SPECIFIC_PATH=("@")
 
+# Ignore prefix path during run "grub-mkconfig".
+# Any path starting with the specified string will be ignored.
+# e.g : if `prefix path` = @, all snapshots beginning with "@/..." will be ignored.
+# Default: ("var/lib/docker" "@var/lib/docker" "@/var/lib/docker")
+GRUB_BTRFS_IGNORE_PREFIX_PATH=("var/lib/docker" "@var/lib/docker" "@/var/lib/docker")
+
+# Ignore specific type of snapper's snapshot during run "grub-mkconfig".
+# Type = single, pre, post.
+# Default: ("")
+GRUB_BTRFS_IGNORE_SNAPPER_TYPE=("")
+
+# Ignore specific description of snapper's snapshot during run "grub-mkconfig".
+# Default: ("")
+GRUB_BTRFS_IGNORE_SNAPPER_DESCRIPTION=("")
+
+# By default "grub-btrfs" automatically detects your boot partition,
+# either located at the system root or on a separate partition,
+# but cannot detect if it is in a subvolume.
+# Change to "true" if you have a boot partition in a different subvolume.
+# Default: "false"
+#GRUB_BTRFS_OVERRIDE_BOOT_PARTITION_DETECTION="true"
+
+# Location of the folder containing the "grub.cfg" file.
+# Use by grub-btrfs to save the file "grub-btrfs.cfg".
+# Might be grub2 on some systems.
+# For example, on Fedora with EFI : "/boot/efi/EFI/fedora"
+# Default: "/boot/grub"
+#GRUB_BTRFS_GRUB_DIRNAME="/boot/grub2"
+
+# Location of kernels/initramfs/microcode.
+# Use by "grub-btrfs" to detect the boot partition and the location of kernels/initrafms/microcodes.
+# Default: "/boot"
+#GRUB_BTRFS_BOOT_DIRNAME="/boot"
+
+# Name/path of grub-mkconfig command, use by "grub-btrfs.service"
+# Might be 'grub2-mkconfig' on some systems (Fedora ...)
+# Default paths are /sbin:/bin:/usr/sbin:/usr/bin,
+# if your path is missing, report it on the upstream project.
+# For example, on Fedora : "/sbin/grub2-mkconfig"
+# You can use only name or full path.
+# Default: grub-mkconfig
+#GRUB_BTRFS_MKCONFIG=/usr/bin/grub2-mkconfig
+
+# Snapper
 # Snapper's config name to use
 # Default: "root"
 #GRUB_BTRFS_SNAPPER_CONFIG="root"
 
-# Disable Grub-btrfs
-# Default: "false"
-#GRUB_BTRFS_DISABLE="false"
-
-# Change to "true" if you have a boot partition in a different subvolume
-# Default: "false"
-#GRUB_BTRFS_OVERRIDE_BOOT_PARTITION_DETECTION="false"
-
-# Might be grub2 on some systems ex. /boot/grub2/...
-# Default: "grub"
-#GRUB_BTRFS_DIRNAME="grub"
-
-# Might be 'grub2-mkconfig' on some systems
-# Default: /usr/bin/grub-mkconfig
-#GRUB_BTRFS_MKCONFIG=/usr/bin/grub2-mkconfig
-
-## Password protection management for submenu,snapshots
+# Password protection management for submenu,snapshots
+# Refer to the Grub documentation https://www.gnu.org/software/grub/manual/grub/grub.html#Authentication-and-authorisation
+# and this comment https://github.com/Antynea/grub-btrfs/issues/95#issuecomment-682295660
+#
 # Add authorized usernames separate by comma (foo,bar)
 # When Grub's password protection is enabled, the superuser is authorized by default, it isn't necessary to add it
-# Default:
-# GRUB_BTRFS_PROTECTION_AUTHORIZED_USERS=""
+# Default: ""
+#GRUB_BTRFS_PROTECTION_AUTHORIZED_USERS="foo,bar"
 #
 # Disable authentication support for submenu of Grub-btrfs only (--unrestricted)
 # doesn't work if GRUB_BTRFS_PROTECTION_AUTHORIZED_USERS isn't empty
-# Default: false
-# GRUB_BTRFS_DISABLE_PROTECTION_SUBMENU="false"
+# Default: "false"
+#GRUB_BTRFS_DISABLE_PROTECTION_SUBMENU="true"

grub-btrfs.path

@@ -1,8 +1,12 @@
 [Unit]
 Description=Monitors for new snapshots
+DefaultDependencies=no
+Requires=\x2esnapshots.mount
+After=\x2esnapshots.mount
+BindsTo=\x2esnapshots.mount
 
 [Path]
 PathModified=/.snapshots
 
 [Install]
-WantedBy=multi-user.target
+WantedBy=\x2esnapshots.mount

grub-btrfs.service

@@ -8,4 +8,4 @@ Environment="PATH=/sbin:/bin:/usr/sbin:/usr/bin"
 # Load environment variables from the configuration
 EnvironmentFile=/etc/default/grub-btrfs/config
 # Regenerate just '/boot/grub/grub-btrfs.cfg' if it exists and is not empty, else regenerate the whole grub menu
-ExecStart=/bin/bash -c 'if [ -s "/boot/${GRUB_BTRFS_DIRNAME:-grub}/grub-btrfs.cfg" ]; then /etc/grub.d/41_snapshots-btrfs; else ${GRUB_BTRFS_MKCONFIG:-/usr/bin/grub-mkconfig} -o /boot/${GRUB_BTRFS_DIRNAME:-grub}/grub.cfg; fi'
+ExecStart=bash -c 'if [ -s "${GRUB_BTRFS_GRUB_DIRNAME:-/boot/grub}/grub-btrfs.cfg" ]; then /etc/grub.d/41_snapshots-btrfs; else ${GRUB_BTRFS_MKCONFIG:-grub-mkconfig} -o ${GRUB_BTRFS_GRUB_DIRNAME:-/boot/grub}/grub.cfg; fi' 

initramfs/Arch Linux/overlay_snap_ro-hook

@@ -0,0 +1,15 @@
+#!/usr/bin/ash
+
+run_latehook() {
+	local root_mnt="/new_root"
+	local current_dev=$(resolve_device "$root"); # resolve devices for blkid
+	if [[ $(blkid "${current_dev}" -s TYPE -o value) = "btrfs" ]] && [[ $(btrfs property get ${root_mnt} ro) != "ro=false" ]]; then # run only on a read only snapshot
+		local lower_dir=$(mktemp -d -p /)
+		local ram_dir=$(mktemp -d -p /)
+		mount --move ${root_mnt} ${lower_dir} # move new_root to lower_dir
+		mount -t tmpfs cowspace ${ram_dir}  #meuh!!! space, you can't test !
+		mkdir -p ${ram_dir}/upper
+		mkdir -p ${ram_dir}/work
+		mount -t overlay -o lowerdir=${lower_dir},upperdir=${ram_dir}/upper,workdir=${ram_dir}/work rootfs ${root_mnt}
+	fi
+}

initramfs/Arch Linux/overlay_snap_ro-install

@@ -0,0 +1,18 @@
+#!/bin/bash
+
+build() {
+    add_module btrfs
+    add_module overlay
+    add_binary btrfs
+    add_binary btrfsck
+    add_binary blkid
+    add_runscript
+}
+
+help() {
+    cat <<HELPEOF
+This hook uses overlayfs to boot on a read only snapshot.
+HELPEOF
+}
+
+# vim: set ft=sh ts=4 sw=4 et:

initramfs/readme.md

@@ -0,0 +1,45 @@
+### Description :
+
+Booting on a snapshot in read-only mode can be tricky.  
+An elegant way is to boot this snapshot using overlayfs (included in the kernel ≥ 3.18).
+
+Using overlayfs, the booted snapshot will behave like a live-cd in non-persistent mode.  
+The snapshot will not be modified, the system will be able to boot correctly, because a writeable folder will be included in the ram.  
+(no more problems due to `/var` not open for writing)
+
+Any changes in this system thus started will be lost when the system is rebooted/shutdown.
+
+To do this, it is necessary to modify the initramfs.  
+This means that any snapshot that does not include this modified initramfs will not be able to benefit from it.  
+(except for separate boot partitions)
+#
+### Installation :
+#### Arch Linux
+1.
+`Pacman -S grub-btrfs`  
+Or if you use git  
+copy the `overlay_snap_ro-install` file to `/etc/initcpio/install/grub-btrfs-overlayfs`  
+copy the `overlay_snap_ro-hook` file to `/etc/initcpio/hooks/grub-btrfs-overlayfs`  
+You must rename the files. (I did it above)
+
+For example :  
+`overlay_snap_ro-install` to `grub-btrfs-overlayfs`  
+`overlay_snap_ro-hook` to `grub-btrfs-overlayfs`  
+Keep in mind that the files must have exactly the same name to ensure a match.
+
+2.
+Edit the file `/etc/mkinitcpio.conf`  
+Added hook `grub-btrfs-overlayfs` at the end of the line `HOOKS`.
+
+For example :  
+`HOOKS=(base udev autodetect modconf block filesystems keyboard fsck grub-btrfs-overlayfs)`  
+You notice that the name of the `hook` must match the name of the 2 installed files. (don't forget it)
+
+3.
+Re-generate your initramfs  
+`mkinitcpio -P` (option -P means, all preset present in `/etc/mkinitcpio.d`)
+
+#### Other distribution
+Refer to your distribution's documentation  
+or contribute to this project to add a paragraph.
+#