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Update 2.6.x-xfs to 2.6.23-rc4.

Also update fs/xfs with external mainline changes.
There were 12 such missing commits that I detected:

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commit ad690ef9e690f6c31f7d310b09ef1314bcec9033
Author: Al Viro <viro@ftp.linux.org.uk>
    xfs ioctl __user annotations

commit 20c2df83d25c6a95affe6157a4c9cac4cf5ffaac
Author: Paul Mundt <lethal@linux-sh.org>
    mm: Remove slab destructors from kmem_cache_create().

commit d0217ac04ca6591841e5665f518e38064f4e65bd
Author: Nick Piggin <npiggin@suse.de>
    mm: fault feedback #1

commit 54cb8821de07f2ffcd28c380ce9b93d5784b40d7
Author: Nick Piggin <npiggin@suse.de>
    mm: merge populate and nopage into fault (fixes nonlinear)

commit d00806b183152af6d24f46f0c33f14162ca1262a
Author: Nick Piggin <npiggin@suse.de>
    mm: fix fault vs invalidate race for linear mappings

commit a569425512253992cc64ebf8b6d00a62f986db3e
Author: Christoph Hellwig <hch@infradead.org>
    knfsd: exportfs: add exportfs.h header

commit 831441862956fffa17b9801db37e6ea1650b0f69
Author: Rafael J. Wysocki <rjw@sisk.pl>
    Freezer: make kernel threads nonfreezable by default

commit 8e1f936b73150f5095448a0fee6d4f30a1f9001d
Author: Rusty Russell <rusty@rustcorp.com.au>
    mm: clean up and kernelify shrinker registration

commit 5ffc4ef45b3b0a57872f631b4e4ceb8ace0d7496
Author: Jens Axboe <jens.axboe@oracle.com>
    sendfile: remove .sendfile from filesystems that use generic_file_sendfile()

commit 8bb7844286fb8c9fce6f65d8288aeb09d03a5e0d
Author: Rafael J. Wysocki <rjw@sisk.pl>
    Add suspend-related notifications for CPU hotplug

commit 59c51591a0ac7568824f541f57de967e88adaa07
Author: Michael Opdenacker <michael@free-electrons.com>
    Fix occurrences of "the the "

commit 0ceb331433e8aad9c5f441a965d7c681f8b9046f
Author: Dmitriy Monakhov <dmonakhov@openvz.org>
    mm: move common segment checks to separate helper function
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Merge of 2.6.x-xfs-melb:linux:29656b by kenmcd.

Network Devices, the Kernel, and You!


Introduction
============
The following is a random collection of documentation regarding
network devices.

struct net_device allocation rules
==================================
Network device structures need to persist even after module is unloaded and
must be allocated with kmalloc.  If device has registered successfully,
it will be freed on last use by free_netdev.  This is required to handle the
pathologic case cleanly (example: rmmod mydriver </sys/class/net/myeth/mtu )

There are routines in net_init.c to handle the common cases of
alloc_etherdev, alloc_netdev.  These reserve extra space for driver
private data which gets freed when the network device is freed. If
separately allocated data is attached to the network device
(dev->priv) then it is up to the module exit handler to free that.

MTU
===
Each network device has a Maximum Transfer Unit. The MTU does not
include any link layer protocol overhead. Upper layer protocols must
not pass a socket buffer (skb) to a device to transmit with more data
than the mtu. The MTU does not include link layer header overhead, so
for example on Ethernet if the standard MTU is 1500 bytes used, the
actual skb will contain up to 1514 bytes because of the Ethernet
header. Devices should allow for the 4 byte VLAN header as well.

Segmentation Offload (GSO, TSO) is an exception to this rule.  The
upper layer protocol may pass a large socket buffer to the device
transmit routine, and the device will break that up into separate
packets based on the current MTU.

MTU is symmetrical and applies both to receive and transmit. A device
must be able to receive at least the maximum size packet allowed by
the MTU. A network device may use the MTU as mechanism to size receive
buffers, but the device should allow packets with VLAN header. With
standard Ethernet mtu of 1500 bytes, the device should allow up to
1518 byte packets (1500 + 14 header + 4 tag).  The device may either:
drop, truncate, or pass up oversize packets, but dropping oversize
packets is preferred.


struct net_device synchronization rules
=======================================
dev->open:
	Synchronization: rtnl_lock() semaphore.
	Context: process

dev->stop:
	Synchronization: rtnl_lock() semaphore.
	Context: process
	Note1: netif_running() is guaranteed false
	Note2: dev->poll() is guaranteed to be stopped

dev->do_ioctl:
	Synchronization: rtnl_lock() semaphore.
	Context: process

dev->get_stats:
	Synchronization: dev_base_lock rwlock.
	Context: nominally process, but don't sleep inside an rwlock

dev->hard_start_xmit:
	Synchronization: netif_tx_lock spinlock.

	When the driver sets NETIF_F_LLTX in dev->features this will be
	called without holding netif_tx_lock. In this case the driver
	has to lock by itself when needed. It is recommended to use a try lock
	for this and return NETDEV_TX_LOCKED when the spin lock fails.
	The locking there should also properly protect against 
	set_multicast_list.

	Context: Process with BHs disabled or BH (timer),
	         will be called with interrupts disabled by netconsole.

	Return codes: 
	o NETDEV_TX_OK everything ok. 
	o NETDEV_TX_BUSY Cannot transmit packet, try later 
	  Usually a bug, means queue start/stop flow control is broken in
	  the driver. Note: the driver must NOT put the skb in its DMA ring.
	o NETDEV_TX_LOCKED Locking failed, please retry quickly.
	  Only valid when NETIF_F_LLTX is set.

dev->tx_timeout:
	Synchronization: netif_tx_lock spinlock.
	Context: BHs disabled
	Notes: netif_queue_stopped() is guaranteed true

dev->set_multicast_list:
	Synchronization: netif_tx_lock spinlock.
	Context: BHs disabled

dev->poll:
	Synchronization: __LINK_STATE_RX_SCHED bit in dev->state.  See
		dev_close code and comments in net/core/dev.c for more info.
	Context: softirq
	         will be called with interrupts disabled by netconsole.