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.
  * 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.
  * Clone with 'mountpoint=none' and 'canmount=noauto' - we mount manually
    and explicitly.
    * For sub-filesystems, that doesn't have a mountpoint property set, we use
      the 'org.zol:mountpoint' to keep track of it's mountpoint.
  * Allow rollback of snapshots instead of clone it and boot from the clone.
* Allow mounting a root- and subfs with mountpoint=legacy set
* Allow mounting a filesystem which is using nativ encryption.
* 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
* 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.

Signed-off-by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2116
Closes #2114

rpm/generic/zfs.spec.in

@@ -189,6 +189,19 @@ Requires:       dracut
 This package contains a dracut module used to construct an initramfs
 image which is ZFS aware.
 
+%if 0%{?_initramfs}
+%package initramfs
+Summary:        Initramfs module
+Group:          System Environment/Kernel
+Requires:       %{name}%{?_isa} = %{version}-%{release}
+Requires:       %{name} = %{version}-%{release}
+Requires:       initramfs-tools
+
+%description initramfs
+This package contains a initramfs module used to construct an initramfs
+image which is ZFS aware.
+%endif
+
 %prep
 %if %{with debug}
     %define debug --enable-debug
@@ -303,6 +316,16 @@ exit 0
 %doc dracut/README.dracut.markdown
 %{_dracutdir}/modules.d/*
 
+%if 0%{?_initramfs}
+%files initramfs
+%doc contrib/initramfs/README.initramfs.markdown
+/usr/share/initramfs-tools/*
+%else
+# Since we're not building the initramfs package,
+# ignore those files.
+%exclude /usr/share/initramfs-tools
+%endif
+
 %changelog
 * Wed Apr  8 2015 Brian Behlendorf <behlendorf1@llnl.gov> - 0.6.4-1
 - Released 0.6.4-1