zfs/dracut
Brian Behlendorf 2cf7f52bc4 Linux compat 2.6.39: mount_nodev()
The .get_sb callback has been replaced by a .mount callback
in the file_system_type structure.  When using the new
interface the caller must now use the mount_nodev() helper.

Unfortunately, the new interface no longer passes the vfsmount
down to the zfs layers.  This poses a problem for the existing
implementation because we currently save this pointer in the
super block for latter use.  It provides our only entry point
in to the namespace layer for manipulating certain mount options.

This needed to be done originally to allow commands like
'zfs set atime=off tank' to work properly.  It also allowed me
to keep more of the original Solaris code unmodified.  Under
Solaris there is a 1-to-1 mapping between a mount point and a
file system so this is a fairly natural thing to do.  However,
under Linux they many be multiple entries in the namespace
which reference the same filesystem.  Thus keeping a back
reference from the filesystem to the namespace is complicated.

Rather than introduce some ugly hack to get the vfsmount and
continue as before.  I'm leveraging this API change to update
the ZFS code to do things in a more natural way for Linux.
This has the upside that is resolves the compatibility issue
for the long term and fixes several other minor bugs which
have been reported.

This commit updates the code to remove this vfsmount back
reference entirely.  All modifications to filesystem mount
options are now passed in to the kernel via a '-o remount'.
This is the expected Linux mechanism and allows the namespace
to properly handle any options which apply to it before passing
them on to the file system itself.

Aside from fixing the compatibility issue, removing the
vfsmount has had the benefit of simplifying the code.  This
change which fairly involved has turned out nicely.

Closes #246
Closes #217
Closes #187
Closes #248
Closes #231
2011-07-01 13:36:39 -07:00
..
90zfs Linux compat 2.6.39: mount_nodev() 2011-07-01 13:36:39 -07:00
Makefile.am Add dracut support 2011-03-17 16:52:04 -07:00
Makefile.in Linux compat 2.6.39: mount_nodev() 2011-07-01 13:36:39 -07:00
README.dracut.markdown Add dracut support 2011-03-17 16:52:04 -07:00

README.dracut.markdown

How to setup a zfs root filesystem using dracut

  1. Install the zfs-dracut package. This package adds a zfs dracut module to the /usr/share/dracut/modules.d/ directory which allows dracut to create an initramfs which is zfs aware.

  2. Set the bootfs property for the bootable dataset in the pool. Then set the dataset mountpoint property to '/'.

    $ zpool set bootfs=pool/dataset $ zfs set mountpoint=/ pool/dataset

Alternately, legacy mountpoints can be used by setting the 'root=' option on the kernel line of your grub.conf/menu.lst configuration file. Then set the dataset mountpoint property to 'legacy'.

$ grub.conf/menu.lst: kernel ... root=ZFS=pool/dataset
$ zfs set mountpoint=legacy pool/dataset
  1. To set zfs module options put them in /etc/modprobe.d/zfs.conf file. The complete list of zfs module options is available by running the modinfo zfs command. Commonly set options include: zfs_arc_min, zfs_arc_max, zfs_prefetch_disable, and zfs_vdev_max_pending.

  2. Finally, create your new initramfs by running dracut.

    $ dracut --force /path/to/initramfs kernel_version