zfsvfs_setup() is called in both zfs_mount and zfs_resume_fs paths.
dmu_objset_set_user(zfsvfs->z_os, zfsvfs) is called early in zfsvfs_setup()
before the setup is actually completed,
thus an under-constructed zfsvfs becomes visible.
Additionally, there is nothing to serialize the two call paths. As a result two
threads can step on each other's toes.
assertion failed: zilog->zl_clean_taskq == NULL, file:
../../common/fs/zfs/zil.c, line: 1772

> $c
vpanic()
0xfffffffffbdf6928()
zil_open+0x45(ffffff1bbc5dd000, fffffffff7993880)
zfsvfs_setup+0x84(ffffffb378d77000, 0)
zfs_resume_fs+0x132(ffffffb378d77000, ffffffb37ddcf000)
zfs_ioc_rollback+0x96(ffffffb37ddcf000, ffffff01dcdc4cd0, ffffff01aa091000)
zfsdev_ioctl+0x215(10a00000000, 5a19, 80465f8, 100003, ffffff01ab318368,
ffffff0004b59e58)
cdev_ioctl+0x39(10a00000000, 5a19, 80465f8, 100003, ffffff01ab318368,
ffffff0004b59e58)
spec_ioctl+0x60(ffffff0197737700, 5a19, 80465f8, 100003,
ffffff01ab318368, ffffff0004b59e58)
fop_ioctl+0x55(ffffff0197737700, 5a19, 80465f8, 100003,
ffffff01ab318368, ffffff0004b59e58)
ioctl+0x9b(7, 5a19, 80465f8)
sys_syscall32+0x1f7()

> ffffff1bbc5dd000::print objset_t os_zil
os_zil = 0xffffff1c053cf7c0
> 0xffffff1c053cf7c0::print zilog_t zl_clean_taskq