[dm-devel] [PATCH v4 0/2] dm: restrict conflicting table loads and improve queue initialization

[Mike Snitzer]

A mapped_device now has a specific immutable type (md->type) that is
set during the initial table_load (see: patch 1/2).

The DM device's request_queue will only have an elevator allocated and
exposed via sysfs if it is request-based (see: patch 2/2).

Please see the individual patch headers for more details.

This patchset is based on agk's DM "editing" tree:
http://www.kernel.org/pub/linux/kernel/people/agk/patches/2.6/editing/
(apply all patches listed in the series file up to NEXT_PATCHES_END)

This patchset also depends on the following linux-2.6-block.git
'for-linus' branch commits:
01effb0 block: allow initialization of previously allocated request_queue
e36f724 block: Adjust elv_iosched_show to return "none" for bio-based DM

I've made a full quilt series available here (builds on 2.6.34):
http://people.redhat.com/msnitzer/patches/dm-queue-init/latest/

I welcome all comments/review.

v4 change:
- dm_set_md_type takes a specific unsigned type rather than dm_table*

v3 changes:
- reduce table_load's md->type_lock protected critical section
- only call dm_setup_md_queue on first table load
  - simplified dm_setup_md_queue as a result
- use existing DM_TYPE_* definitions instead of duplicating them
- eliminate overly verbose comments as the code speaks for itself much
  more clearly

v2 changes:
- remove do_resume and table_clear interlock
- rebase to agk's latest "editing" tree
- drop the dm_get_verified_mdptr and find_device_noinit patches that
  were at the end of v1; can revisit that code duplication cleanup later

Mike Snitzer (2):
  dm: prevent table type changes after initial table load
  dm: only initialize full request_queue for request-based device

 drivers/md/dm-ioctl.c |   24 +++++++++
 drivers/md/dm.c       |  131 +++++++++++++++++++++++++++++++++++++------------
 drivers/md/dm.h       |    7 +++
 3 files changed, 130 insertions(+), 32 deletions(-)