[dm-devel] [PATCH 0/6] dm: restrict conflicting table loads and improve queue initialization

[Mike Snitzer]

This work has expanded in scope somewhat (based on Mikulas' suggestion
that I pursue more constrained table/device type switching to avoid
Kiyoshi's locking concerns).  A mapped_device now has a specific type
(md->type) that is managed in table_{load,clear} (see patch 3/6).

It should be noted that patch 4/6 is labeled "v8".  I still believe
v7's locking strategy is _not_ prone to problematic deadlock, as I
detailed/questioned here: http://lkml.org/lkml/2010/5/21/175
v7 is still available for viewing here:
https://patchwork.kernel.org/patch/101270/

But this new series eliminates v7's locking between table_load() and
do_resume() -- fixed md->type made this possible.  So these changes
may be more desirable overall (adds some clearer exclusion and state
transitions that I feel help DM without being too restrictive).

Please see the individual patch headers for more details.

A monolithic patch is also available here:
http://people.redhat.com/msnitzer/patches/dm-queue-init/monolithic.patch

I welcome all comments/review.  Hopefully others will find that what
I've done is worthwhile.

Mike Snitzer (6):
  block: Adjust elv_iosched_show to return "none" for bio-based DM
  dm ioctl: interlock resume and table clear
  dm: prevent table type changes after initial table load
  dm: only initialize full request_queue for request-based device
  dm ioctl: introduce dm_get_verified_mdptr
  dm ioctl: introduce find_device_noinit

 block/elevator.c      |    2 +-
 drivers/md/dm-ioctl.c |  148 +++++++++++++++++++++++++++------
 drivers/md/dm.c       |  216 +++++++++++++++++++++++++++++++++++++++++-------
 drivers/md/dm.h       |   12 +++
 4 files changed, 318 insertions(+), 60 deletions(-)