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Wojciech Małota-Wójcik e6ea31de9f
Rollback before zfs root is mounted 
On my machines I observe random failures caused by rollback happening 
after zfs root is mounted. I've observed two types of failures:

- zfs-rollback-bootfs.service fails saying that rollback must be
  done just before mounting the dataset
- boot process fails and rescue console is entered.

After making this modification and testing it for couple of days 
none of those problems have been observed anymore.

I don't know if `dracut-mount.service` is still needed in the 
`After` directive. Maybe someone else is able to address this?

Reviewed-by: Gregory Bartholomew <gregory.lee.bartholomew@gmail.com>
Signed-off-by: Wojciech Małota-Wójcik <59281144+outofforest@users.noreply.github.com>
Closes #15025
 		2023-07-20 09:55:22 -07:00
..
02zfsexpandknowledge Ubuntu 22.04 integration: ShellCheck 2022-11-18 11:24:48 -08:00
90zfs Rollback before zfs root is mounted 2023-07-20 09:55:22 -07:00
.gitignore autoconf: use include directives instead of recursing down contrib 2022-05-10 10:19:44 -07:00
Makefile.am contrib: dracut: fix race with root=zfs:dset when necessities required 2023-03-31 09:47:48 -07:00
README.md contrib: dracut: README.md 2022-06-30 10:43:27 -07:00

README.md

Basic setup

  1. Install zfs-dracut
  2. Set mountpoint=/ for your root dataset (for compatibility, legacy also works, but is not recommended for new installations): 
    zfs set mountpoint=/ pool/dataset
  3. Either (a) set bootfs= on the pool to the dataset: 
    zpool set bootfs=pool/dataset pool
  4. Or (b) append root=zfs:pool/dataset to your kernel cmdline.
  5. Re-generate your initrd and update it in your boot bundle

Encrypted datasets have keys loaded automatically or prompted for.

If the root dataset contains children with mountpoint=s of /etc, /bin, /lib*, or /usr, they're mounted too.

For complete documentation, see dracut.zfs(7).

cmdline

  1. root= Root dataset is…
    (empty) the first bootfs= after zpool import -aN
    zfs:AUTO, zfs:, zfs (as above, but overriding other autoselection methods)
    ZFS=pool/dataset pool/dataset
    zfs:pool/dataset (as above)

    All +es are replaced with spaces (i.e. to boot from root pool/data set, pass root=zfs:root+pool/data+set).

    The dataset can be at any depth, including being the pool's root dataset (i.e. root=zfs:pool).

    rootfstype=zfs is equivalent to root=zfs:AUTO, rootfstype=zfs root=pool/dataset is equivalent to root=zfs:pool/dataset.

  2. spl_hostid: passed to zgenhostid -f, useful to override the /etc/hostid file baked into the initrd.

  3. bootfs.snapshot, bootfs.snapshot=snapshot-name: enables zfs-snapshot-bootfs.service, which creates a snapshot $root_dataset@$(uname -r) (or, in the second form, $root_dataset@snapshot-name) after pool import but before the rootfs is mounted. Failure to create the snapshot is noted, but booting continues.

  4. bootfs.rollback, bootfs.rollback=snapshot-name: enables zfs-rollback-bootfs.service, which -Rf rolls back to $root_dataset@$(uname -r) (or, in the second form, $root_dataset@snapshot-name) after pool import but before the rootfs is mounted. Failure to roll back will fall down to the rescue shell. This has obvious potential for data loss: make sure your persistent data is not below the rootfs and you don't care about any intermediate snapshots.

  5. If both bootfs.snapshot and bootfs.rollback are set, bootfs.rollback is ordered after bootfs.snapshot.

  6. zfs_force, zfs.force, zfsforce: add -f to all zpool import invocations. May be useful. Use with caution.