zfs recv -x and -o fail when property is invalid (missing)

[prometheanfire]

System information

Type	Version/Name
Distribution Name	gentoo
Distribution Version	updated
Linux Kernel	4.9
Architecture	x86_86
ZFS Version	probably around 0.7.0rc2
SPL Version	same time period

Describe the problem you're observing

# zfs send -Lecp storage-pool/remote-backups/vm01-vms/usr@local-backup-201707091859 | zfs recv -duvF -o mountpoint=none backup04-zp00/backups
receiving full stream of storage-pool/remote-backups/vm01-vms/usr@local-backup-201707091859 into backup04-zp00/backups/remote-backups/vm01-vms/usr@local-backup-201707091859
cannot receive new filesystem stream: property 'mountpoint' does not apply to datasets of this type

I'd like to be able to use a simple script to sync backup to an external drive (offsite) and just exclude mountpoint in either the send or recv if the property exists or not

Describe how to reproduce the problem

use recv -x mountpoint on a volume

[loli10K]

use recv -x mountpoint on a volume

I've seen the word "volume" misused sometimes to describe filesystems (or datasets), i'm asking just to be sure: is this a ZVOL you're trying to receive?

[prometheanfire]

Yes, a zvol, the actual script, simply masks the mountpoint attribute on ALL recvs, including zvols.

[loli10K]

This is to be expected, "mountpoint" is not a valid ZVOL property:

root@linux:~# zfs get type testpool/zvol 
NAME           PROPERTY  VALUE   SOURCE
testpool/zvol  type      volume  -
root@linux:~# zfs set mountpoint=none testpool/zvol 
cannot set property for 'testpool/zvol': 'mountpoint' does not apply to datasets of this type

To send/recv volumes you probably want "volmode" instead, which recently landed in 0.7.0-rc5 (cf8738d):

The volmode property may be set to control the visibility of ZVOL
block devices.

This allow switching ZVOL between three modes:
   full - existing fully functional behaviour (default)
   dev  - hide partitions on ZVOL block devices
   none - not exposing volumes outside ZFS

Additionally the new zvol_volmode module parameter can be used to
control the default behaviour.

This functionality can be used, for instance, on "backup" pools to
avoid cluttering /dev with unneeded zd* devices.

[prometheanfire]

ya, I'm aware that mountpoint is an invalid property for zvols, didn't know about the new zvol_volmode thing, which is nice as well (and I'll start using it whenever I update).

What I was looking for is for zfs recv to ignore the unsetting of properties that don't exist, instead of erroring as it does now.

[loli10K]

What I was looking for is for zfs recv to ignore the unsetting of properties that don't exist, instead of erroring as it does now.

Use zfs send -R: it doesn't really make much sense to ignore invalid -x|-o options specifically set from the command line for a single dataset.

[prometheanfire]

I was using zfs send -p (because -R doesn't work if you've removed a couple of datasets snapshots, it assumes all child datasets have that snapshot). I was basically looking to send everything, but ignore one or two properties.

[loli10K]

I was basically looking to send everything, but ignore one or two properties.

With zfs send -R we're going to ignore invalid properties because we could have different dataset types (filesystems and volumes) in the same send stream, but for a single dataset you're expected to know the destination type: why can't you omit the invalid properties from the command line? Just "ignoring" an option you specifically asked to be applied doesn't look good.

[prometheanfire]

can you send a replication stream of a single dataset? I can't do it for the whole pool because the whole pool isn't snapshotted, some datasets have had their snapshots removed (cache, replaceable data, etc) and a send -R on a pool like that doesn't work. see #5196 for more info on that.

edit:

I can confirm that a replication stream does work for a single dataset, so I'll use --replicate instead of --props.

tested with both the following with success.

zfs send -LecR storage-pool/remote-backups/vm01-vms/usr@local-backup-201707091859 | zfs recv -duvF -o mountpoint=none backup04-zp00/backups-test

and

zfs send -LecR storage-pool/remote-backups/vm01-vms/usr@local-backup-201707091859 | zfs recv -duvF -x mountpoint backup04-zp00/backups-test

where storage-pool/remote-backups/vm01-vms/usr is a volume

the problem then becomes --replicate sends all child snapshots (older snapshots of the same dataset) when I only want the one, I will move on to doing incrementals but the initial sync is a bit ineffecient.

[loli10K]

send -R on a pool like that doesn't work. see #5196 for more info on that.

I know, if you remember we tried to fix that but didn't succeed. You can still cherry-pick my old PR in your local overlay if you need it.

I can confirm that a replication stream does work for a single dataset, so I'll use --replicate instead of --props.

You could also avoid using -x|-o mountpoint when receiving a ZVOL. Anyway, glad it worked out for you in the end.