Re: [ANNOUNCE] util-linux-ng v2.17.1

[Karel Zak <kzak-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

On Fri, Feb 26, 2010 at 02:18:50PM +0000, Ricardo M. Correia wrote:
> On Sex, 2010-02-26 at 14:52 +0100, Karel Zak wrote:
> > Hi Andreas,
> >  The TYPE is used by mount(8) or fsck(8) if the fstype is not
> >  explicitly defined by user.
> > 
> >  I don't know if anything depends on the TYPE, but I don't see
> >  /sbin/mount.zfs, so it seems that zfs-fuse guys use something other.
> 
> Right, ZFS filesystems are mounted in zfs-fuse automatically when a ZFS
> pool is imported into the system or manually with the "zfs" command. The
> latter calls into the zfs-fuse daemon, which issues a fuse_mount() call.
> This mimics the behavior in the Solaris ZFS implementation.

 Hmm.. we have udevd, in an ideal world zfs-fuse would be integrated
 with udev. 

> I would expect the /sbin/mount.zfs command to only work when the
> mountpoint property of a ZFS filesystem is set to 'legacy', otherwise
> ZFS will usually mount the filesystem by itself in the proper place
> (which depends on the mountpoint property and the dataset hierarchy
> within the pool).
> 
> Most importantly, I don't think it would be easy to determine which
> filesystems are inside of a ZFS pool. This would require traversing the
> dataset hierarchy within a pool, which is very difficult to implement if
> you don't use the existing ZFS code, especially when you have
> RAID-Z/Z2/Z3 pools. We'd be better off using the 'zdb' command (which
> contains an entire implementation of ZFS's DMU code in userspace).

 Yes, the same "problem" we have with DM/MD/... the solution is to
 detect that there is any "volume_member" and then use specific tools
 (dmsetup, cryptsetup, mdadm, ...) to create a virtual mountable
 device. 

> Not sure if this helps or not for this discussion (more information is
> never bad, right?) :-)

 Right. BTW, I assume the same discussion for btrfs ;-)

    Karel

-- 
 Karel Zak  <kzak-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
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