zfs suspend/resume

[Hongjiang Zhang]

Hi,

I want to implement a feature to freeze/thaw the ZFS filesystem through zfs_suspend/zfs_resume. This is used for FreeBSD in Hyper-V: Hyper-V supports VSS (Volume Shadow Copy), and it requires the VM running on Hyper-V to support filesystem Freeze/Thaw.

I found zfs_ioc_rollback has invoked zfs_suspend_fs and zfs_resume_fs. But either zfs_suspend_fs or zfs_resume_fs was exposed to userland. I don't understand why zfs_suspend_fs/zfs_resume_fs cannot be used through zfs_ioctl. Anyone know? Or is it reasonable to add zfs_ioc_suspend and zfs_ioc_resume?

Thanks
Hongjiang Zhang