On Tue, Jan 19, 2016 at 05:00:25PM +0000, Alan Somers wrote: > Author: asomers > Date: Tue Jan 19 17:00:25 2016 > New Revision: 294329 > URL: https://svnweb.freebsd.org/changeset/base/294329 > > Log: > Disallow zvol-backed ZFS pools > > Using zvols as backing devices for ZFS pools is fraught with panics and > deadlocks. For example, attempting to online a missing device in the > presence of a zvol can cause a panic when vdev_geom tastes the zvol. Better > to completely disable vdev_geom from ever opening a zvol. The solution > relies on setting a thread-local variable during vdev_geom_open, and > returning EOPNOTSUPP during zvol_open if that thread-local variable is set. > > Remove the check for MUTEX_HELD(&zfsdev_state_lock) in zvol_open. Its intent > was to prevent a recursive mutex acquisition panic. However, the new check > for the thread-local variable also fixes that problem. > > Also, fix a panic in vdev_geom_taste_orphan. For an unknown reason, this > function was set to panic. But it can occur that a device disappears during > tasting, and it causes no problems to ignore this departure. > > Reviewed by: delphij > MFC after: 1 week > Relnotes: yes > Sponsored by: Spectra Logic Corp > Differential Revision: https://reviews.freebsd.org/D4986
I've just been bit by this pretty hard. I have a bhyve VM that's backed by a zvol. The VM is running root-on-zfs. I wrote some experimental code that's now preventing the VM from booting (kernel panic due to userland change). Since I can't import the pool, I have no way of fixing the problem. I'm probably just going to go revert this commit locally on my box so I can get some work done. Thanks, -- Shawn Webb HardenedBSD GPG Key ID: 0x6A84658F52456EEE GPG Key Fingerprint: 2ABA B6BD EF6A F486 BE89 3D9E 6A84 658F 5245 6EEE
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