History log of /freebsd-head/sys/dev/hyperv/utilities/hv_snapshot.c
Revision Date Author Comments
fca200a88ae9fbd2d8f4102978dc82ebbeb55488 20-Dec-2016 sephe <sephe@FreeBSD.org> hyperv/ic: Rename cleaned up header file.

MFC after: 1 week
Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D8846
3d66160304e937a632e787e3b661110cd0115ab3 20-Dec-2016 sephe <sephe@FreeBSD.org> hyperv/ic: Cleanup common struct and functions.

MFC after: 1 week
Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D8845
cf8bc16b1e75f7216f63c11ea15fa20fe37be571 15-Nov-2016 sephe <sephe@FreeBSD.org> hyperv/vss: Add driver and tools for VSS

VSS stands for "Volume Shadow Copy Service". Unlike virtual machine
snapshot, it only takes snapshot for the virtual disks, so both
filesystem and applications have to aware of it, and cooperate the
whole VSS process.

This driver exposes two device files to the userland:


Normally userland programs should _not_ mess with this device file.
It is currently used by the hv_vss_daemon(8), which freezes and
thaws the filesystem. NOTE: currently only UFS is supported, if
the system mounts _any_ other filesystems, the hv_vss_daemon(8)
will veto the VSS process.

If hv_vss_daemon(8) was disabled, then this device file must be
opened, and proper ioctls must be issued to keep the VSS working.


Userland application can opened this device file to receive the
VSS freeze notification, hold the VSS for a while (mainly to flush
application data to filesystem), release the VSS process, and
receive the VSS thaw notification i.e. applications can run again.

The VSS will still work, even if this device file is not opened.
However, only filesystem consistency is promised, if this device
file is not opened or is not operated properly.

hv_vss_daemon(8) is started by devd(8) by default. It can be disabled
by editting /etc/devd/hyperv.conf.

Submitted by: Hongjiang Zhang <honzhan microsoft com>
Reviewed by: kib, mckusick
MFC after: 3 weeks
Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D8224