docs: add qemu-storage-daemon(1) man page

Document the qemu-storage-daemon tool. Most of the command-line options
are identical to their QEMU counterparts. Perhaps Sphinx hxtool
integration could be extended to extract documentation for individual
command-line options so they can be shared. For now the
qemu-storage-daemon simply refers to the qemu(1) man page where the
command-line options are identical.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20201209103802.350848-3-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

docs/tools/conf.py

@@ -20,6 +20,8 @@
 man_pages = [
     ('qemu-img', 'qemu-img', u'QEMU disk image utility',
      ['Fabrice Bellard'], 1),
+    ('qemu-storage-daemon', 'qemu-storage-daemon', u'QEMU storage daemon',
+     [], 1),
     ('qemu-nbd', 'qemu-nbd', u'QEMU Disk Network Block Device Server',
      ['Anthony Liguori <anthony@codemonkey.ws>'], 8),
     ('qemu-pr-helper', 'qemu-pr-helper', 'QEMU persistent reservation helper',

docs/tools/index.rst

@@ -11,6 +11,7 @@ Contents:
    :maxdepth: 2
 
    qemu-img
+   qemu-storage-daemon
    qemu-nbd
    qemu-pr-helper
    qemu-trace-stap

docs/tools/qemu-storage-daemon.rst

@@ -0,0 +1,148 @@
+QEMU Storage Daemon
+===================
+
+Synopsis
+--------
+
+**qemu-storage-daemon** [options]
+
+Description
+-----------
+
+qemu-storage-daemon provides disk image functionality from QEMU, qemu-img, and
+qemu-nbd in a long-running process controlled via QMP commands without running
+a virtual machine. It can export disk images, run block job operations, and
+perform other disk-related operations. The daemon is controlled via a QMP
+monitor and initial configuration from the command-line.
+
+The daemon offers the following subset of QEMU features:
+
+* Block nodes
+* Block jobs
+* Block exports
+* Throttle groups
+* Character devices
+* Crypto and secrets
+* QMP
+* IOThreads
+
+Commands can be sent over a QEMU Monitor Protocol (QMP) connection. See the
+:manpage:`qemu-storage-daemon-qmp-ref(7)` manual page for a description of the
+commands.
+
+The daemon runs until it is stopped using the ``quit`` QMP command or
+SIGINT/SIGHUP/SIGTERM.
+
+**Warning:** Never modify images in use by a running virtual machine or any
+other process; this may destroy the image. Also, be aware that querying an
+image that is being modified by another process may encounter inconsistent
+state.
+
+Options
+-------
+
+.. program:: qemu-storage-daemon
+
+Standard options:
+
+.. option:: -h, --help
+
+  Display help and exit
+
+.. option:: -V, --version
+
+  Display version information and exit
+
+.. option:: -T, --trace [[enable=]PATTERN][,events=FILE][,file=FILE]
+
+  .. include:: ../qemu-option-trace.rst.inc
+
+.. option:: --blockdev BLOCKDEVDEF
+
+  is a block node definition. See the :manpage:`qemu(1)` manual page for a
+  description of block node properties and the :manpage:`qemu-block-drivers(7)`
+  manual page for a description of driver-specific parameters.
+
+.. option:: --chardev CHARDEVDEF
+
+  is a character device definition. See the :manpage:`qemu(1)` manual page for
+  a description of character device properties. A common character device
+  definition configures a UNIX domain socket::
+
+  --chardev socket,id=char1,path=/tmp/qmp.sock,server,nowait
+
+.. option:: --export [type=]nbd,id=<id>,node-name=<node-name>[,name=<export-name>][,writable=on|off][,bitmap=<name>]
+  --export [type=]vhost-user-blk,id=<id>,node-name=<node-name>,addr.type=unix,addr.path=<socket-path>[,writable=on|off][,logical-block-size=<block-size>][,num-queues=<num-queues>]
+  --export [type=]vhost-user-blk,id=<id>,node-name=<node-name>,addr.type=fd,addr.str=<fd>[,writable=on|off][,logical-block-size=<block-size>][,num-queues=<num-queues>]
+
+  is a block export definition. ``node-name`` is the block node that should be
+  exported. ``writable`` determines whether or not the export allows write
+  requests for modifying data (the default is off).
+
+  The ``nbd`` export type requires ``--nbd-server`` (see below). ``name`` is
+  the NBD export name. ``bitmap`` is the name of a dirty bitmap reachable from
+  the block node, so the NBD client can use NBD_OPT_SET_META_CONTEXT with the
+  metadata context name "qemu:dirty-bitmap:BITMAP" to inspect the bitmap.
+
+  The ``vhost-user-blk`` export type takes a vhost-user socket address on which
+  it accept incoming connections. Both
+  ``addr.type=unix,addr.path=<socket-path>`` for UNIX domain sockets and
+  ``addr.type=fd,addr.str=<fd>`` for file descriptor passing are supported.
+  ``logical-block-size`` sets the logical block size in bytes (the default is
+  512). ``num-queues`` sets the number of virtqueues (the default is 1).
+
+.. option:: --monitor MONITORDEF
+
+  is a QMP monitor definition. See the :manpage:`qemu(1)` manual page for
+  a description of QMP monitor properties. A common QMP monitor definition
+  configures a monitor on character device ``char1``::
+
+  --monitor chardev=char1
+
+.. option:: --nbd-server addr.type=inet,addr.host=<host>,addr.port=<port>[,tls-creds=<id>][,tls-authz=<id>][,max-connections=<n>]
+  --nbd-server addr.type=unix,addr.path=<path>[,tls-creds=<id>][,tls-authz=<id>][,max-connections=<n>]
+
+  is a server for NBD exports. Both TCP and UNIX domain sockets are supported.
+  TLS encryption can be configured using ``--object`` tls-creds-* and authz-*
+  secrets (see below).
+
+  To configure an NBD server on UNIX domain socket path ``/tmp/nbd.sock``::
+
+  --nbd-server addr.type=unix,addr.path=/tmp/nbd.sock
+
+.. option:: --object help
+  --object <type>,help
+  --object <type>[,<property>=<value>...]
+
+  is a QEMU user creatable object definition. List object types with ``help``.
+  List object properties with ``<type>,help``. See the :manpage:`qemu(1)`
+  manual page for a description of the object properties.
+
+Examples
+--------
+Launch the daemon with QMP monitor socket ``qmp.sock`` so clients can execute
+QMP commands::
+
+  $ qemu-storage-daemon \
+      --chardev socket,path=qmp.sock,server,nowait,id=char1 \
+      --monitor chardev=char1
+
+Export raw image file ``disk.img`` over NBD UNIX domain socket ``nbd.sock``::
+
+  $ qemu-storage-daemon \
+      --blockdev driver=file,node-name=disk,filename=disk.img \
+      --nbd-server addr.type=unix,addr.path=nbd.sock \
+      --export type=nbd,id=export,node-name=disk,writable=on
+
+Export a qcow2 image file ``disk.qcow2`` as a vhosts-user-blk device over UNIX
+domain socket ``vhost-user-blk.sock``::
+
+  $ qemu-storage-daemon \
+      --blockdev driver=file,node-name=file,filename=disk.qcow2 \
+      --blockdev driver=qcow2,node-name=qcow2,file=file \
+      --export type=vhost-user-blk,id=export,addr.type=unix,addr.path=vhost-user-blk.sock,node-name=qcow2
+
+See also
+--------
+
+:manpage:`qemu(1)`, :manpage:`qemu-block-drivers(7)`, :manpage:`qemu-storage-daemon-qmp-ref(7)`