Merge branch 'for-2.6.34' of git://git.kernel.dk/linux-2.6-block

* 'for-2.6.34' of git://git.kernel.dk/linux-2.6-block: (38 commits)
  block: don't access jiffies when initialising io_context
  cfq: remove 8 bytes of padding from cfq_rb_root on 64 bit builds
  block: fix for "Consolidate phys_segment and hw_segment limits"
  cfq-iosched: quantum check tweak
  blktrace: perform cleanup after setup error
  blkdev: fix merge_bvec_fn return value checks
  cfq-iosched: requests "in flight" vs "in driver" clarification
  cciss: Fix problem with scatter gather elements in the scsi half of the driver
  cciss: eliminate unnecessary pointer use in cciss scsi code
  cciss: do not use void pointer for scsi hba data
  cciss: factor out scatter gather chain block mapping code
  cciss: fix scatter gather chain block dma direction kludge
  cciss: simplify scatter gather code
  cciss: factor out scatter gather chain block allocation and freeing
  cciss: detect bad alignment of scsi commands at build time
  cciss: clarify command list padding calculation
  cfq-iosched: rethink seeky detection for SSDs
  cfq-iosched: rework seeky detection
  block: remove padding from io_context on 64bit builds
  block: Consolidate phys_segment and hw_segment limits
  ...

1 files changed, 14 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-block b/Documentation/ABI/testing/sysfs-block
index d2f90334bb93..4873c759d535 100644
--- a/Documentation/ABI/testing/sysfs-block
+++ b/Documentation/ABI/testing/sysfs-block
@@ -128,3 +128,17 @@ Description:
                 preferred request size for workloads where sustained
                 throughput is desired.  If no optimal I/O size is
                 reported this file contains 0.
+
+What:           /sys/block/<disk>/queue/nomerges
+Date:           January 2010
+Contact:
+Description:
+                Standard I/O elevator operations include attempts to
+                merge contiguous I/Os. For known random I/O loads these
+                attempts will always fail and result in extra cycles
+                being spent in the kernel. This allows one to turn off
+                this behavior on one of two ways: When set to 1, complex
+                merge checks are disabled, but the simple one-shot merges
+                with the previous I/O request are enabled. When set to 2,
+                all merge tries are disabled. The default value is 0 -
+                which enables all types of merge tries.