* 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#2116Closes#2114
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