only allow unprivileged passthrough for commands without effects v2

[Christoph Hellwig]

Hi all,

this series first fixes a few minor issues in the CES log support in the
host and target drivers and then uses the log to deny unprivileged
passthrough of commands that have effects, where the only practically
relevant effect is the modification of contents of the data stored in the
namespace.

Changes since v1:
 - make sure ctrl->effects an nshead->effects is always available
 - initializse known effects at init time
 - remove the use_workqueue field in nvmet_req
 - fix up a commit message

Diffstat:
 host/core.c        |   95 ++++++++++++++++++++++++++++-------------------------
 host/ioctl.c       |   20 ++++++-----
 host/nvme.h        |    3 +
 target/admin-cmd.c |   37 +++++++++++---------
 target/nvmet.h     |    1 
 target/passthru.c  |   61 ++++++++++++++++++++--------------
 6 files changed, 122 insertions(+), 95 deletions(-)