Merge remote-tracking branch 'stefanha/block' into staging

# By MORITA Kazutaka (5) and others
# Via Stefan Hajnoczi
* stefanha/block:
  block: for HMP commit() operations on 'all', skip non-COW drives
  sheepdog: add support for connecting to unix domain socket
  sheepdog: use inet_connect to simplify connect code
  sheepdog: accept URIs
  move socket_set_nodelay to osdep.c
  slirp/tcp_subr.c: fix coding style in tcp_connect
  dataplane: remove EventPoll in favor of AioContext
  virtio-blk: fix unplug + virsh reboot
  ide/macio: Fix macio DMA initialisation.

qemu-options.hx

@@ -2108,23 +2108,13 @@ QEMU supports using either local sheepdog devices or remote networked
 devices.
 
 Syntax for specifying a sheepdog device
-@table @list
-``sheepdog:<vdiname>''
-
-``sheepdog:<vdiname>:<snapid>''
-
-``sheepdog:<vdiname>:<tag>''
-
-``sheepdog:<host>:<port>:<vdiname>''
-
-``sheepdog:<host>:<port>:<vdiname>:<snapid>''
-
-``sheepdog:<host>:<port>:<vdiname>:<tag>''
-@end table
+@example
+sheepdog[+tcp|+unix]://[host:port]/vdiname[?socket=path][#snapid|#tag]
+@end example
 
 Example
 @example
-qemu-system-i386 --drive file=sheepdog:192.0.2.1:30000:MyVirtualMachine
+qemu-system-i386 --drive file=sheepdog://192.0.2.1:30000/MyVirtualMachine
 @end example
 
 See also @url{http://http://www.osrg.net/sheepdog/}.