The commit 976222e0

    xen/blkback: Move the check for misaligned I/O higher.

moved it a bit to high. The preq->vbdev was not set, so the
check for misaligned I/O would cause a NULL pointer derefence.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

The previous name ('fast_flush_area') had nothing to do with what it
does right now. Changing the names so that the code dealing with
mapping pages in and out of the guest is called xen_blkbk_[map|unmap].
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

We move it up higher to be in same loop that actually computes
the sector number.

This way, all of the code that deals with verifying that the
request is correct is all done before we do any of the
page mapping, I/O submission, etc.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

We take out the chunk of code dealing with mapping to the guest
of pages into the xen_blk_map_buf code. And we also move the
vbd_translate to be done much earlier.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Moving it so that the code that 'fast_flush_area' code is
close to the code that deals with it so that the reader
won't lose focus.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

We seperate the bio allocation (bio_alloc) from the bio submission so
that the error paths are much easier, and also so that the bio
submission can be done in one tight loop. It also makes the
plug/unplug calls much much easier.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

commit 7eaceacc ("block: remove per-queue plugging")
added two new interfaces to plug and unplug: blk_start_plug
and blk_finish_plug. Lets use those.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

+               sring_x86_64 = (struct blkif_x86_64_sring *)blkif->blk_ring_area->addr;

WARNING: line over 80 characters
+               BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, PAGE_SIZE);

as breaking them up really does not help that much.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

checkpatch.pl suggested that we don't use the typdef in common.h
and this triggered this avalanche of patches.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

The WRITE_BARRIER was missing the REQ_WRITE option. This
was causing the blktap to die.
Signed-off-by: NTom Goetz <tom.goetz@virtualcomputer.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

The patch titled:"xen/blkback: Use 'vzalloc' for page arrays and pre-allocate pages."
allocates the structures and its member variables using the 'vzalloc'.

Daniel Stodden pointed out that vzalloc is good when we use
big number of pages - while these are at the max two pages.

We can do this using kzalloc. Also the GFP_HIGHMEM does not
work properly with Xen, so take that out.

We will have to revisit this when a "get_empty_pages_and_pagevec"
type API shows up to leverage that.

BugLink: http://mid.gmane.org/1299898639.11681.227.camel@agari.van.xensource.com

CC: Daniel Stodden <daniel.stodden@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Instead of doing copy grants lets do mapping grants using
the M2P(and P2M) override mechanism.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Conflicts:

	drivers/xen/blkback/blkback.c

Previously we would allocate the array for page using 'kmalloc' which
we can as easily do with 'vzalloc'. The pre-allocation of pages
was done a bit differently in the past - it used to be that
the balloon driver would export "alloc_empty_pages_and_pagevec"
which would have in one function created an array, allocated
the pages, balloned the pages out (so the memory behind those
pages would be non-present), and provide us those pages.

This was OK as those pages were shared between other guest and
the only thing we needed was to "swizzel" the MFN of those pages
to point to the other guest MFN. We can still "swizzel" the MFNs
using the M2P (and P2M) override API calls, but for the sake of
simplicity we are dropping the balloon API calls. We can return
to those later on.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Following in the steps of patch:
"xen: Union the blkif_request request specific fields" this patch
changes the blkback. Per the original patch:

"Prepare for extending the block device ring to allow request
specific fields, by moving the request specific fields for
reads, writes and barrier requests to a union member."

Cc: Owen Smith <owen.smith@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Bundle the lot of discrete variables into a single structure.
This is based on what was done in the xen-netback driver:
xen: netback: Move global/static variables into struct xen_netbk.
(094944631cc5a9d6e623302c987f78117c0bf7ac)
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Cherry-pick and modified from 69d64727c42eecd47fdf82c15a54474d21a4012a
("blkback/blktap2: simplify address translations"):

"There are quite a number of places where e.g. page->va->page
translations happen.

Besides yielding smaller code (source and binary), a second goal is to
make it easier to determine where virtual addresses of pages allocated
through alloc_empty_pages_and_pagevec() are really used (in turn in
order to determine whether using highmem pages would be possible
there)."

The second goal is not the purpose of this patch - it is just to
make it easier to read the code.

linux-2.6-pvops:
 * Stripped drivers/xen/gntdev/*
 * Stripped drivers/xen/netback/*

[v2: Stripped blktap off]
Signed-off-by: NJan Beulich <jbeulich@novell.com>
Signed-off-by: NDaniel Stodden <daniel.stodden@citrix.com>
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

The API for opening a block device has changed since 2.6.32. The
correct function to open a device is blkdev_get_by_dev.

TODO: Double check xen-blkfront.c

A guest can cause the backend driver to leak a kernel thread. Such
leaked threads hold references to the device, whichmakes the device
impossible to tear down. If shut down, the guest remains a zombie
domain, the xenwatch process hangs, and most xm commands will stop
working.

This patch tries to do the following for blkback:
    - identify/extract idempotent teardown operations,
    - add/move the invocation of said teardown operation
      right before we're about to allocate new resources in the
      Connected states.

[ linux-2.6.18-xen.hg 59f097ef181b ]
Signed-off-by: NLaszlo Ersek <lersek@redhat.com>
Signed-off-by: NKeir Fraser <keir@xen.org>
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

Signed-off-by: NK. Y. Srinivasan <ksrinivasan@novell.com>
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

First cut at flushing blkback data when first connecting
blkback.  This should avoid the pygrub issues we are experiencing
in (RedHat bugzilla) 466681.

[ 2.6.18-xen.hg commit 63b4d7f56688 ]
Signed-off-by: NChris Lalancette <clalance@redhat.com>
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

Since backend_info is hidden away now.
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

Support dynamic resizing of virtual block devices. This patch supports
both file backed block devices as well as physical devices that can be
dynamically resized on the host side.
Signed-off-by: NK. Y. Srinivasan <ksrinivasan@novell.com>
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

Direct driver_data access is obsolete and will disappear.
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

blkbk is rather generic for a modular distro style kernel.
Signed-off-by: NIan Campbell <ian.campbell@citrix.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

We neglect to check the return value of xenbus_register_backend
and take actions when that fails. This patch fixes that and adds
code to deal with those type of failures.
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

Remove unused local prototype; group headers.
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

Impact: build fix

I'm not sure if blkback should be using these functions, but in the
meantime export them to allow blkback to be a module.
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

It's a user-mode header for users of /dev/evtchn
Signed-off-by: NJeremy Fitzhardinge <jeremy@goop.org>

Signed-off-by: NIan Campbell <ian.campbell@citrix.com>
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Conflicts:

	drivers/xen/Makefile

* 'for-linus' of git://oss.sgi.com/xfs/xfs:
  xfs: use proper interfaces for on-stack plugging
  xfs: fix xfs_debug warnings
  xfs: fix variable set but not used warnings
  xfs: convert log tail checking to a warning
  xfs: catch bad block numbers freeing extents.
  xfs: push the AIL from memory reclaim and periodic sync
  xfs: clean up code layout in xfs_trans_ail.c
  xfs: convert the xfsaild threads to a workqueue
  xfs: introduce background inode reclaim work
  xfs: convert ENOSPC inode flushing to use new syncd workqueue
  xfs: introduce a xfssyncd workqueue
  xfs: fix extent format buffer allocation size
  xfs: fix unreferenced var error in xfs_buf.c

Also, applied patch from Tony Luck that fixes ia64:
  xfs_destroy_workqueues() should not be tagged with__exit
in the branch before merging.