Add `block.create_options` to block storage drivers

[huoxingdawang]

Is there an existing issue for this?

• There is no existing issue for this feature

What are you currently unable to do

When using Incus with a LINSTOR storage backend where LINSTOR itself uses ZFS as the underlying storage pool (e.g., with volblocksize=16K), it is often necessary to tune the filesystem creation parameters to align I/O with the underlying backend's block size.

For example, with a ZFS volblocksize of 16 KiB, one would want to create ext4 filesystems with:

mkfs.ext4 -b 4096 -E stripe-width=4,stride=4 <device>

This ensures that ext4's internal I/O patterns align with the ZFS block boundaries, avoiding read-modify-write amplification and improving performance.

LINSTOR natively supports filesystem configuration via:

linstor resource-group set-property default FileSystem/Type ext4
linstor resource-group set-property default FileSystem/MkfsParams "-b 4096 -E stripe-width=4,stride=4"

However, Incus does not delegate filesystem creation to LINSTOR. Instead, it invokes makeFSType() (utils.go) directly to format the block device after it is allocated. As a result, any FileSystem/MkfsParams configuration set on the LINSTOR resource group is completely ignored by Incus.

The makeFSType function currently only accepts a Label via its mkfsOptions struct and hard-codes ext4 extra options (-E nodiscard,lazy_itable_init=0,lazy_journal_init=0), providing no way to pass additional user-defined parameters.

What do you think would need to be added

Add a new block.mkfs_options configuration key to the LINSTOR driver, mirroring the pattern already used by block.filesystem and block.mount_options.

And I am glad to submit a PR implementing this change if possible.

[bensmrs]

As with #3011, that sounds like quite a specific option, and I’d rather only allow that as a raw key. WDYT @stgraber?

[stgraber]

@bensmrs Given we already have some pretty specific block.XYZ options shared by a number of storage drivers. having a block.create_options to match block.mount_options seems reasonable here I think.

[stgraber]

Re-titled to make this broader than Linstor.

[huoxingdawang]

Thanks for broadening the scope.

I agree that a generic block.create_options key is the right direction and is better than a LINSTOR-only key.

I am happy to work on a PR for this. My plan is:

1. Add block.create_options for block-backed storage drivers.
2. Extend filesystem creation plumbing so these options are passed to mkfs consistently.
3. Wire this into all relevant drivers currently formatting filesystems in Incus (btrfs, ceph, linstor, lvm, truenas, zfs).

If that scope looks good, I can start working on the PR.

[stgraber]

Yep, that sounds right