Merge branch 'for-4.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Pull cgroup updates from Tejun Heo:

 - cgroup v2 interface is now official.  It's no longer hidden behind a
   devel flag and can be mounted using the new cgroup2 fs type.

   Unfortunately, cpu v2 interface hasn't made it yet due to the
   discussion around in-process hierarchical resource distribution and
   only memory and io controllers can be used on the v2 interface at the
   moment.

 - The existing documentation which has always been a bit of mess is
   relocated under Documentation/cgroup-v1/. Documentation/cgroup-v2.txt
   is added as the authoritative documentation for the v2 interface.

 - Some features are added through for-4.5-ancestor-test branch to
   enable netfilter xt_cgroup match to use cgroup v2 paths.  The actual
   netfilter changes will be merged through the net tree which pulled in
   the said branch.

 - Various cleanups

* 'for-4.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: rename cgroup documentations
  cgroup: fix a typo.
  cgroup: Remove resource_counter.txt in Documentation/cgroup-legacy/00-INDEX.
  cgroup: demote subsystem init messages to KERN_DEBUG
  cgroup: Fix uninitialized variable warning
  cgroup: put controller Kconfig options in meaningful order
  cgroup: clean up the kernel configuration menu nomenclature
  cgroup_pids: fix a typo.
  Subject: cgroup: Fix incomplete dd command in blkio documentation
  cgroup: kill cgrp_ss_priv[CGROUP_CANFORK_COUNT] and friends
  cpuset: Replace all instances of time_t with time64_t
  cgroup: replace unified-hierarchy.txt with a proper cgroup v2 documentation
  cgroup: rename Documentation/cgroups/ to Documentation/cgroup-legacy/
  cgroup: replace __DEVEL__sane_behavior with cgroup2 fs type

Author: torvalds

Documentation/cgroups/00-INDEX renamed to Documentation/cgroup-v1/00-INDEX

@@ -24,7 +24,5 @@ net_prio.txt
 	- Network priority cgroups details and usages.
 pids.txt
 	- Process number cgroups details and usages.
-resource_counter.txt
-	- Resource Counter API.
 unified-hierarchy.txt
 	- Description the new/next cgroup interface.

Documentation/cgroups/blkio-controller.txt renamed to Documentation/cgroup-v1/blkio-controller.txt

@@ -84,8 +84,7 @@ Throttling/Upper Limit policy
 
 - Run dd to read a file and see if rate is throttled to 1MB/s or not.
 
-		# dd if=/mnt/common/zerofile of=/dev/null bs=4K count=1024
-		# iflag=direct
+        # dd iflag=direct if=/mnt/common/zerofile of=/dev/null bs=4K count=1024
         1024+0 records in
         1024+0 records out
         4194304 bytes (4.2 MB) copied, 4.0001 s, 1.0 MB/s
@@ -374,82 +373,3 @@ One can experience an overall throughput drop if you have created multiple
 groups and put applications in that group which are not driving enough
 IO to keep disk busy. In that case set group_idle=0, and CFQ will not idle
 on individual groups and throughput should improve.
-
-Writeback
-=========
-
-Page cache is dirtied through buffered writes and shared mmaps and
-written asynchronously to the backing filesystem by the writeback
-mechanism.  Writeback sits between the memory and IO domains and
-regulates the proportion of dirty memory by balancing dirtying and
-write IOs.
-
-On traditional cgroup hierarchies, relationships between different
-controllers cannot be established making it impossible for writeback
-to operate accounting for cgroup resource restrictions and all
-writeback IOs are attributed to the root cgroup.
-
-If both the blkio and memory controllers are used on the v2 hierarchy
-and the filesystem supports cgroup writeback, writeback operations
-correctly follow the resource restrictions imposed by both memory and
-blkio controllers.
-
-Writeback examines both system-wide and per-cgroup dirty memory status
-and enforces the more restrictive of the two.  Also, writeback control
-parameters which are absolute values - vm.dirty_bytes and
-vm.dirty_background_bytes - are distributed across cgroups according
-to their current writeback bandwidth.
-
-There's a peculiarity stemming from the discrepancy in ownership
-granularity between memory controller and writeback.  While memory
-controller tracks ownership per page, writeback operates on inode
-basis.  cgroup writeback bridges the gap by tracking ownership by
-inode but migrating ownership if too many foreign pages, pages which
-don't match the current inode ownership, have been encountered while
-writing back the inode.
-
-This is a conscious design choice as writeback operations are
-inherently tied to inodes making strictly following page ownership
-complicated and inefficient.  The only use case which suffers from
-this compromise is multiple cgroups concurrently dirtying disjoint
-regions of the same inode, which is an unlikely use case and decided
-to be unsupported.  Note that as memory controller assigns page
-ownership on the first use and doesn't update it until the page is
-released, even if cgroup writeback strictly follows page ownership,
-multiple cgroups dirtying overlapping areas wouldn't work as expected.
-In general, write-sharing an inode across multiple cgroups is not well
-supported.
-
-Filesystem support for cgroup writeback
----------------------------------------
-
-A filesystem can make writeback IOs cgroup-aware by updating
-address_space_operations->writepage[s]() to annotate bio's using the
-following two functions.
-
-* wbc_init_bio(@wbc, @bio)
-
-  Should be called for each bio carrying writeback data and associates
-  the bio with the inode's owner cgroup.  Can be called anytime
-  between bio allocation and submission.
-
-* wbc_account_io(@wbc, @page, @bytes)
-
-  Should be called for each data segment being written out.  While
-  this function doesn't care exactly when it's called during the
-  writeback session, it's the easiest and most natural to call it as
-  data segments are added to a bio.
-
-With writeback bio's annotated, cgroup support can be enabled per
-super_block by setting MS_CGROUPWB in ->s_flags.  This allows for
-selective disabling of cgroup writeback support which is helpful when
-certain filesystem features, e.g. journaled data mode, are
-incompatible.
-
-wbc_init_bio() binds the specified bio to its cgroup.  Depending on
-the configuration, the bio may be executed at a lower priority and if
-the writeback session is holding shared resources, e.g. a journal
-entry, may lead to priority inversion.  There is no one easy solution
-for the problem.  Filesystems can try to work around specific problem
-cases by skipping wbc_init_bio() or using bio_associate_blkcg()
-directly.