Few small fixes

[vojtechtrefny]

Fix for three bugs from freedesktop bugzilla.

[vpodzime]

Looks good to me otherwise.

[vpodzime]

Really only on GPT?

[vojtechtrefny]

I have no idea. This is what ZFSOnLinux FAQ says to do -- https://github.com/zfsonlinux/zfs/wiki/FAQ#udisks2-creating-devmapper-entries-for-zvol

[vpodzime]

OK

[Trucido]

original reporter of the udisks rule for zfs_member here (disclaimer: not officially affiliated with ZoL); let me elaborate if there is any confusion:

ZFS on MBR partitions/slices is extremely rare, this was to avoid unnecessary scanning.

Edit: Also, I think maybe the partition type codes in the rule are only in GPT anyhow, but it is always labeled zfs_member from what I can tell.

In WHOLE_DISK mode (just giving ZFS entire disks to do it's thing, the recommended method) ZoL creates two GPT partitions (mainly just to identify itself, not sure if this is the case on solaris).
If user chooses partitions/slices instead of giving entire disks to ZFS; all of the guides describe creating GPT - with the same part ID's (and BSD creates GPT slices by default with same part ID's IIRC)

so it's safe to say yes GPT, besides rare setups (worst case scenario for the rare MBR setups would be they see some zfs devices in udisks2 which is harmless; they can't be mounted ejected or anything). so let's reduce MBR scanning overhead for these extremely rare ZFS installations.

we're still missing one more ID for dedicated log disk or partition (ZIL/SLOG), but this is only an issue if a dedicated logs device was added to array (less common, rare for desktops).
I haven't had time to track down the ZIL/SLOG partition ID and verify it's always the same ID (etc. etc.).

The only exception to "almost-always-gpt" thing MIGHT be the above mentioned missing ID for logs disk/partition (because it could potentially be on a MBR disk shared with other partitions), but is still likely to be GPT.

To reduce confusion, dedicated log or 'logs' is also called ZIL or SLOG. think of it as an external dedicated journal device attached to a larger ZFS array - only utilized for small O_SYNC writes. desktop users are unlikely to have arrays which would benefit enough from it IMO which is why I said uncommon and rare for desktops

Also, if someone could tell me where the proper place is to report additions to this rule (after I find the above mentioned log partition ID) I'd appreciate it since I originally reported this on freedesktop.org's bugzilla

Please excuse any typos; briefly written after waking up without coffee.

[vpodzime]

ZFS on MBR partitions/slices is extremely rare, this was to avoid unnecessary scanning.

This is not about unnecessary scanning. The udev rule only compares a few properties that are already set anyway. So the real question is if the above combination is the only one it should match. And it looks like it isn't. What if somebody for example has an MBR-partitioned SSD and wants to use one of the partitions as a cache for ZFS?

[vpodzime]

I originally reported this on freedesktop.org's bugzilla

Please file issues here at GitHub.