[PATCHSET] blkcg: kill policy node and blkg->dev, take#2

[Tejun Heo]

Hello, guys.

This is the second take of blkcg-kill-policy-node-and-blkg_dev
patchset.  Changes from the last take[L] are,

* 0001-blkcg-make-CONFIG_BLK_CGROUP-bool.patch added to allow caling
  into blkcg from block core to clear blkg's on elevator switch.

* For patches 0005-0008 added.  These ensure that blkcg policies are
  quiescent and no blkg exists during elevator switch.  0005-0006 are
  lifted from the pending second patchset and will be used for policy
  registration too.

* 0013-blkcg-use-the-usual-get-blkg-path-for-root-blkio_gro.patch
  fixed for !CONFIG_CFQ_GROUP_IOSCHED.

* 0009-blkcg-move-rcu_read_lock-outside-of-blkio_group-get-.patch is
  the 0001 RCU fix patch.  It turns out the RCU lock isn't protecting
  blkg at all but blkcg.  Patch description updated accordingly.

The next patchset will update blkcg such that there's one blkg per
cgroup - request_queue association.  Initially, all blkg's will
contain data for all policies registered on the system but policy
registration will be made per-request_queue.

The original patchset description follows.

blk-cgroup, blk-throttle and cfq-iosched are pretty tightly tangled
and untangling requires seemingly unrelated changes and addition of
some transitional stuff.  Some are in this patchset but they'll be
more prominent in the second patchset.  With that said, this patchset
concentrates on removing blkio_policy_node and blkio_group->dev.

blkio_policy_node carries configuration per cgroup-request_queue
association separately from the matching blkio_group.  The goal seems
to be allowing configuration of missing devices and retaining
configuration across hot unplug/plug cycles.  Such behavior is very
different from existing conventions, misleading and unnecessary.  This
patchset moves configuration to blkio_group and removes
blkio_policy_node.

blkg->dev removal is much simpler.  blkg->dev is used to print out
device number when printing out per-device configurations or
statistics.  The device name can be easily determined by following the
associated request_queue from blkg instead.

This patchset contains the following 17 patches.

0001-blkcg-make-CONFIG_BLK_CGROUP-bool.patch
0002-cfq-don-t-register-propio-policy-if-CONFIG_CFQ_GROUP.patch
0003-elevator-clear-auxiliary-data-earlier-during-elevato.patch
0004-elevator-make-elevator_init_fn-return-0-errno.patch
0005-block-implement-blk_queue_bypass_start-end.patch
0006-block-extend-queue-bypassing-to-cover-blkcg-policies.patch
0007-blkcg-make-blkio_list_lock-irq-safe.patch
0008-blkcg-shoot-down-blkio_groups-on-elevator-switch.patch
0009-blkcg-move-rcu_read_lock-outside-of-blkio_group-get-.patch
0010-blkcg-update-blkg-get-functions-take-blkio_cgroup-as.patch
0011-blkcg-use-q-and-plid-instead-of-opaque-void-for-blki.patch
0012-blkcg-add-blkio_policy-array-and-allow-one-policy-pe.patch
0013-blkcg-use-the-usual-get-blkg-path-for-root-blkio_gro.patch
0014-blkcg-factor-out-blkio_group-creation.patch
0015-blkcg-don-t-allow-or-retain-configuration-of-missing.patch
0016-blkcg-kill-blkio_policy_node.patch
0017-blkcg-kill-the-mind-bending-blkg-dev.patch

0001-0004: misc preps including elevator switch update

0005-0008: ensure blkcg policies are quiescent across elvswitch

0009-0014: move common part of blkg management into blkcg core

0015-0016: kill blkio_policy_node

0017     : kill blkg->dev

This patchset is on top of v3.3-rc1 and also available in the
following git branch.

  git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc.git blkcg-kill-pn

 block/Kconfig.iosched    |    5 
 block/blk-cgroup.c       |  684 +++++++++++++++--------------------------------
 block/blk-cgroup.h       |  106 ++-----
 block/blk-core.c         |   53 +++
 block/blk-throttle.c     |  266 +++++-------------
 block/blk.h              |    6 
 block/cfq-iosched.c      |  286 +++++++------------
 block/cfq.h              |    7 
 block/deadline-iosched.c |    8 
 block/elevator.c         |  115 +++----
 block/noop-iosched.c     |    8 
 include/linux/blkdev.h   |    5 
 include/linux/elevator.h |    2 
 init/Kconfig             |    2 
 14 files changed, 568 insertions(+), 985 deletions(-)

Thanks.

--
tejun

[L] http://thread.gmane.org/gmane.linux.kernel/1241094
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