Merge branch 'for-2.6.36' of git://git.kernel.dk/linux-2.6-block

* 'for-2.6.36' of git://git.kernel.dk/linux-2.6-block: (149 commits)
  block: make sure that REQ_* types are seen even with CONFIG_BLOCK=n
  xen-blkfront: fix missing out label
  blkdev: fix blkdev_issue_zeroout return value
  block: update request stacking methods to support discards
  block: fix missing export of blk_types.h
  writeback: fix bad _bh spinlock nesting
  drbd: revert "delay probes", feature is being re-implemented differently
  drbd: Initialize all members of sync_conf to their defaults [Bugz 315]
  drbd: Disable delay probes for the upcomming release
  writeback: cleanup bdi_register
  writeback: add new tracepoints
  writeback: remove unnecessary init_timer call
  writeback: optimize periodic bdi thread wakeups
  writeback: prevent unnecessary bdi threads wakeups
  writeback: move bdi threads exiting logic to the forker thread
  writeback: restructure bdi forker loop a little
  writeback: move last_active to bdi
  writeback: do not remove bdi from bdi_list
  writeback: simplify bdi code a little
  writeback: do not lose wake-ups in bdi threads
  ...

Fixed up pretty trivial conflicts in drivers/block/virtio_blk.c and
drivers/scsi/scsi_error.c as per Jens.

arch/ia64/include/asm/scatterlist.h

@@ -2,15 +2,6 @@
 #define _ASM_IA64_SCATTERLIST_H
 
 #include <asm-generic/scatterlist.h>
-/*
- * It used to be that ISA_DMA_THRESHOLD had something to do with the
- * DMA-limits of ISA-devices.  Nowadays, its only remaining use (apart
- * from the aha1542.c driver, which isn't 64-bit clean anyhow) is to
- * tell the block-layer (via BLK_BOUNCE_ISA) what the max. physical
- * address of a page is that is allocated with GFP_DMA.  On IA-64,
- * that's 4GB - 1.
- */
-#define ISA_DMA_THRESHOLD	0xffffffff
 #define ARCH_HAS_SG_CHAIN
 
 #endif /* _ASM_IA64_SCATTERLIST_H */