blk-cgroup: config options re-arrangement

This patch fixes few usability and configurability issues.

o All the cgroup based controller options are configurable from
  "Genral Setup/Control Group Support/" menu. blkio is the only exception.
  Hence make this option visible in above menu and make it configurable from
  there to bring it inline with rest of the cgroup based controllers.

o Get rid of CONFIG_DEBUG_CFQ_IOSCHED.

  This option currently does two things.

  - Enable printing of cgroup paths in blktrace
  - Enables CONFIG_DEBUG_BLK_CGROUP, which in turn displays additional stat
    files in cgroup.

  If we are using group scheduling, blktrace data is of not really much use
  if cgroup information is not present. To get this data, currently one has to
  also enable CONFIG_DEBUG_CFQ_IOSCHED, which in turn brings the overhead of
  all the additional debug stat files which is not desired.

  Hence, this patch moves printing of cgroup paths under
  CONFIG_CFQ_GROUP_IOSCHED.

  This allows us to get rid of CONFIG_DEBUG_CFQ_IOSCHED completely. Now all
  the debug stat files are controlled only by CONFIG_DEBUG_BLK_CGROUP which
  can be enabled through config menu.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Divyesh Shah <dpshah@google.com>
Reviewed-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 5 insertions, 11 deletions

diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched
index fc71cf071fb2..3199b76f795d 100644
--- a/block/Kconfig.iosched
+++ b/block/Kconfig.iosched
@@ -23,7 +23,8 @@ config IOSCHED_DEADLINE
 
 config IOSCHED_CFQ
         tristate "CFQ I/O scheduler"
-        select BLK_CGROUP if CFQ_GROUP_IOSCHED
+        # If BLK_CGROUP is a module, CFQ has to be built as module.
+        depends on (BLK_CGROUP=m && m) || !BLK_CGROUP || BLK_CGROUP=y
         default y
         ---help---
           The CFQ I/O scheduler tries to distribute bandwidth equally
@@ -33,22 +34,15 @@ config IOSCHED_CFQ
 
           This is the default I/O scheduler.
 
+          Note: If BLK_CGROUP=m, then CFQ can be built only as module.
+
 config CFQ_GROUP_IOSCHED
         bool "CFQ Group Scheduling support"
-        depends on IOSCHED_CFQ && CGROUPS
+        depends on IOSCHED_CFQ && BLK_CGROUP
         default n
         ---help---
           Enable group IO scheduling in CFQ.
 
-config DEBUG_CFQ_IOSCHED
-        bool "Debug CFQ Scheduling"
-        depends on CFQ_GROUP_IOSCHED
-        select DEBUG_BLK_CGROUP
-        default n
-        ---help---
-          Enable CFQ IO scheduling debugging in CFQ. Currently it makes
-          blktrace output more verbose.
-
 choice
         prompt "Default I/O scheduler"
         default DEFAULT_CFQ