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

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

 Hi Andreas,

On Thu, Feb 25, 2010 at 06:13:50PM -0700, Andreas Dilger wrote:
> On 2010-02-22, at 03:30, Karel Zak wrote:
>> The stable util-linux-ng 2.17.1 release is available at
>>
>>   ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/v2.17/
>>
>> Feedback and bug reports, as always, are welcomed.
>
> Hi Karel,
> attached is an updated version of the ZFS device detection.  It includes 
> support for extracting the pool name (LABEL) along with the pool_guid 
> (UUID).

 Thanks! I'll review & commit it later.

> One question I had was regarding naming of the TYPE.  Currently we are  
> using "zfs" for this, but the current code is only really detecting the 
> volume information and has noting to do with mountable filesystems.

 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.

> Extracting filesystem names/mountpoints/guids is basically impossible at 
> this stage w/o actually having ZFS active (in a similar manner that 
> extracting ext2/3/4 filesystem information from an unconfigured LVM PV is 
> impossible).
>

 See for example vmfs.c where we have "VMFS" (mountable FS) and also
 "VMFS_volume_member" (storage). The both TYPEs are completely
 independent and you can selectively probe for FS or for the special
 volume rather than probe always for both. I think this concept is
 better that add a new identifier (e.g. CONTAINER). 
 
 Note, we have USAGE identifier to specify kind of the type, for
 example raid, filesystem, crypto, etc. This is necessary for
 udevd and some desktop tools. (try: blkid -p -o udev <device>).

> Should we rename the TYPE to be "zfs_vdev" (ZFS equivalent to "lvm2pv") 
> instead of the current "zfs"?  It is probably more desirable to keep 

 Yes, TYPE="zfs" (mountable FS) and TYPE="zfs_volume_member" makes
 sense. (The "_volume_member" is horribly long, but we use it for
 compatibility with udev world.)

> "zfs" for future filesystem mountpoint identification.  For now I've left 
> it as "zfs" but wouldn't mind changing it now while there are not any 
> real users of this.

> Have you considered adding CONTAINER or similar identification to the  
> blkid.tab file, so that it is possible to determine that the filesystem 
> with LABEL="home" is on CONTAINER="39u4yr-f5WW-dtD7-jDfr- 
> usGd-pYWf-qy6xKE", which in turn is the UUID of an lvm2pv on /dev/sda2?

 I'd like to avoid this if possible.

    Karel

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