Initramfs scripts for ZoL.

* Supports booting of a ZFS snapshot.
  Do this by cloning the snapshot into a dataset. If this, the resulting
  dataset, already exists, destroy it. Then mount it on root.
  * If snapshot does not exist, use base dataset (the part before '@')
    as boot filesystem instead.
  * Clone with 'mountpoint=none' and 'canmount=noauto' - we mount manually
    and explicitly.
  * Allow rollback of snapshots instead of clone it and boot from the clone.
  * If no snapshot is specified on the 'root=' kernel command line, but there
    is an '@', then get a list of snapshots below that filesystem and ask the
    user which to use.
* Allows mounting a rootfs with mountpoint=legacy set
* Support all currently used kernel command line arguments
  All the different distributions have their own standard on what to specify
  on the kernel command line to boot of a ZFS filesystem.
  * Extra options:
    * zfsdebug=(on,yes,1)	Show extra debugging information
    * zfsforce=(on,yes,1)	Force import the pool
    * rollback=(on,yes,1)	Rollback (instead of clone) the snapshot
* Don't auto import pools when loading module - keep better control of the imports.
* Only try to import pool if it haven't already been imported
  * This will negate the need to force import a pool that have not been exported cleanly.
  * Support exclusion of pools to import by setting ZFS_POOL_EXCEPTIONS in /etc/default/zfs.
* Support additional configuration variable ZFS_INITRD_ADDITIONAL_DATASETS
  to mount additional filesystems not located under your root dataset.
* Include /etc/modprobe.d/{zfs,spl}.conf in the initrd if it/they exist.
* Include the udev rule to use by-vdev for pool imports.
* Include the /etc/default/zfs file to the initrd.
* Only try /dev/disk/by-* in the initrd if USE_DISK_BY_ID is set.
  * Use /dev/disk/by-vdev before anything.
  * Add /dev as a last ditch attempt.
  * Fallback to using the cache file if that exist if nothing else worked.
* Use /sbin/modprobe instead of built-in (BusyBox) modprobe.
  This gets rid of the message "modprobe: can't load module zcommon".
  Thanx to pcoultha for finding this.
* Ignore filesystems with mountpoint=none. Might not be correct though...
  Needs more testing.

Signed-off-by: Turbo Fredriksson <[email protected]>
Closes: openzfs#2116, openzfs#2114

Makefile.am

@@ -7,7 +7,7 @@ include $(top_srcdir)/config/tgz.am
 
 SUBDIRS = include rpm
 if CONFIG_USER
-SUBDIRS += dracut udev etc man scripts lib cmd contrib
+SUBDIRS += dracut udev etc man scripts lib cmd contrib initramfs
 endif
 if CONFIG_KERNEL
 SUBDIRS += module

configure.ac

@@ -128,6 +128,7 @@ AC_CONFIG_FILES([
 	include/sys/fs/Makefile
 	include/sys/fm/Makefile
 	include/sys/fm/fs/Makefile
+	initramfs/Makefile
 	scripts/Makefile
 	scripts/zpios-profile/Makefile
 	scripts/zpios-test/Makefile

initramfs/Makefile.am

@@ -0,0 +1,23 @@
+initrddir = $(datarootdir)/initramfs-tools
+
+initrd_SCRIPTS = conf-hooks.d/zfs hooks/zfs scripts/zfs
+
+EXTRA_DIST = \
+	$(top_srcdir)/initramfs/conf-hooks.d/zfs \
+	$(top_srcdir)/initramfs/hooks/zfs \
+	$(top_srcdir)/initramfs/scripts/zfs
+
+install-initrdSCRIPTS: $(EXTRA_DIST)
+	for d in conf-hooks.d hooks scripts; do \
+	  $(MKDIR_P) $(DESTDIR)$(initrddir)/$$d; \
+	  cp $(top_srcdir)/initramfs/$$d/zfs \
+	    $(DESTDIR)$(initrddir)/$$d/; \
+	done
+	if [ -f etc/init.d/zfs ]; then \
+	  $(MKDIR_P) $(DESTDIR)$(DEFAULT_INITCONF_DIR); \
+	  cp $(top_srcdir)/etc/init.d/zfs \
+	    $(DESTDIR)$(DEFAULT_INITCONF_DIR)/; \
+	fi
+
+distclean-local::
+	-$(RM) $(top_srcdir)/initramfs/scripts/zfs

initramfs/conf-hooks.d/zfs

@@ -0,0 +1,2 @@
+# Force the inclusion of Busybox in the initramfs.
+BUSYBOX=y

initramfs/hooks/zfs

@@ -0,0 +1,112 @@
+#!/bin/sh
+#
+# Add ZoL filesystem capabilities to an initrd, usually for a native ZFS root.
+#
+
+# This hook installs udev rules for ZoL.
+PREREQ="zdev"
+
+# These prerequisites are provided by the zfsutils package. The zdb utility is
+# not strictly required, but it can be useful at the initramfs recovery prompt.
+COPY_EXEC_LIST="/sbin/zdb /sbin/zpool /sbin/zfs /sbin/mount.zfs"
+
+# These prerequisites are provided by the base system.
+COPY_EXEC_LIST="$COPY_EXEC_LIST /bin/hostname /sbin/blkid"
+
+# Explicitly specify all kernel modules because automatic dependency resolution
+# is unreliable on many systems.
+BASE_MODULES="zlib_deflate spl zavl zcommon znvpair zunicode zfs"
+CRPT_MODULES="sun-ccm sun-gcm sun-ctr"
+MANUAL_ADD_MODULES_LIST="$BASE_MODULES"
+
+# Generic result code.
+RC=0
+
+case $1 in
+prereqs)
+	echo "$PREREQ"
+	exit 0
+	;;
+esac
+
+for ii in $COPY_EXEC_LIST
+do
+	if [ ! -x "$ii" ]
+	then
+		echo "Error: $ii is not executable."
+		RC=2
+	fi
+done
+
+if [ "$RC" -ne 0 ]
+then
+	exit "$RC"
+fi
+
+. /usr/share/initramfs-tools/hook-functions
+
+mkdir -p "$DESTDIR/etc/"
+
+# ZDB uses pthreads for some functions, but the library dependency is not
+# automatically detected. The `find` utility and extended `cp` options are
+# used here because libgcc_s.so could be in a subdirectory of /lib for
+# multi-arch installations.
+cp --target-directory="$DESTDIR" --parents $(find /lib -type f -name libgcc_s.so.1)
+
+for ii in $COPY_EXEC_LIST
+do
+	copy_exec "$ii"
+done
+
+for ii in $MANUAL_ADD_MODULES_LIST
+do
+	manual_add_modules "$ii"
+done
+
+if [ -f "/etc/hostname" ]
+then
+	cp -p "/etc/hostname" "$DESTDIR/etc/"
+else
+	hostname >"$DESTDIR/etc/hostname"
+fi
+
+for ii in zfs zfs.conf spl spl.conf
+do  
+	if [ -f "/etc/modprobe.d/$ii" ]; then
+		if [ ! -d "$DESTDIR/etc/modprobe.d" ]; then
+			mkdir -p $DESTDIR/etc/modprobe.d
+		fi
+		cp -p "/etc/modprobe.d/$ii" $DESTDIR/etc/modprobe.d/
+	fi
+done
+
+# The spl-dkms package ensures that the /etc/hostid file exists.
+# NB: Commentary in the spl-dkms.postinst script.
+[ -f "/etc/hostid" ] && cp -p "/etc/hostid" "$DESTDIR/etc/hostid"
+
+# Install the zpool.cache file.
+[ -d /boot/zfs ] && cp -r /boot/zfs "$DESTDIR/boot"
+[ ! -d "$DESTDIR/boot/zfs" ] && mkdir -p "$DESTDIR/boot/zfs"
+[ -f /etc/zfs/zpool.cache ] && cp /etc/zfs/zpool.cache $DESTDIR/boot/zfs/
+
+# With pull request #1476 (not yet merged) comes a verbose warning
+# if /usr/bin/net doesn't exist or isn't executable. Just create
+# a dummy...
+[ ! -d "$DESTDIR/usr/bin" ] && mkdir -p "$DESTDIR/usr/bin"
+if [ ! -x "$DESTDIR/usr/bin/net" ]; then
+    touch "$DESTDIR/usr/bin/net"
+    chmod +x "$DESTDIR/usr/bin/net"
+fi
+
+# Copy the udev vdev rule
+if [ -f /etc/zfs/vdev_id.conf ]; then
+    [ ! -d "$DESTDIR/etc/zfs" ] && mkdir -p $DESTDIR/etc/zfs
+    cp /lib/udev/rules.d/69-vdev.rules $DESTDIR/lib/udev/rules.d
+    cp /etc/zfs/vdev_id.conf $DESTDIR/etc/zfs/vdev_id.conf
+fi
+
+# Copy the defaults file
+[ ! -d "$DESTDIR/etc/default" ] && mkdir -p "$DESTDIR/etc/default"
+cp /etc/default/zfs $DESTDIR/etc/default/
+
+exit 0

initramfs/scripts/.gitignore

@@ -0,0 +1 @@
+zfs