Merge branch 'linus' into core/rcu

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+                      Network Block Device (TCP version)
+                                       
+   What is it: With this compiled in the kernel (or as a module), Linux
+   can use a remote server as one of its block devices. So every time
+   the client computer wants to read, e.g., /dev/nb0, it sends a
+   request over TCP to the server, which will reply with the data read.
+   This can be used for stations with low disk space (or even diskless -
+   if you boot from floppy) to borrow disk space from another computer.
+   Unlike NFS, it is possible to put any filesystem on it, etc. It should
+   even be possible to use NBD as a root filesystem (I've never tried),
+   but it requires a user-level program to be in the initrd to start.
+   It also allows you to run block-device in user land (making server
+   and client physically the same computer, communicating using loopback).
+   
+   Current state: It currently works. Network block device is stable.
+   I originally thought that it was impossible to swap over TCP. It
+   turned out not to be true - swapping over TCP now works and seems
+   to be deadlock-free, but it requires heavy patches into Linux's
+   network layer.
+   
+   For more information, or to download the nbd-client and nbd-server
+   tools, go to http://nbd.sf.net/.
+
+   Howto: To setup nbd, you can simply do the following:
+
+   First, serve a device or file from a remote server:
+
+   nbd-server <port-number> <device-or-file-to-serve-to-client>
+
+   e.g.,
+	root@server1 # nbd-server 1234 /dev/sdb1
+
+	(serves sdb1 partition on TCP port 1234)
+
+   Then, on the local (client) system:
+
+   nbd-client <server-name-or-IP> <server-port-number> /dev/nb[0-n]
+
+   e.g.,
+	root@client1 # nbd-client server1 1234 /dev/nb0
+
+	(creates the nb0 device on client1)
+
+   The nbd kernel module need only be installed on the client
+   system, as the nbd-server is completely in userspace. In fact,
+   the nbd-server has been successfully ported to other operating
+   systems, including Windows.