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-rw-r--r--docs/tools/qemu-storage-daemon.rst19
1 files changed, 19 insertions, 0 deletions
diff --git a/docs/tools/qemu-storage-daemon.rst b/docs/tools/qemu-storage-daemon.rst
index 086493ebb3..3ec4bdd914 100644
--- a/docs/tools/qemu-storage-daemon.rst
+++ b/docs/tools/qemu-storage-daemon.rst
@@ -74,6 +74,7 @@ Standard options:
.. 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>]
+ --export [type=]fuse,id=<id>,node-name=<node-name>,mountpoint=<file>[,growable=on|off][,writable=on|off]
is a block export definition. ``node-name`` is the block node that should be
exported. ``writable`` determines whether or not the export allows write
@@ -92,6 +93,16 @@ Standard options:
``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).
+ The ``fuse`` export type takes a mount point, which must be a regular file,
+ on which to export the given block node. That file will not be changed, it
+ will just appear to have the block node's content while the export is active
+ (very much like mounting a filesystem on a directory does not change what the
+ directory contains, it only shows a different content while the filesystem is
+ mounted). Consequently, applications that have opened the given file before
+ the export became active will continue to see its original content. If
+ ``growable`` is set, writes after the end of the exported file will grow the
+ block node to fit.
+
.. option:: --monitor MONITORDEF
is a QMP monitor definition. See the :manpage:`qemu(1)` manual page for
@@ -196,6 +207,14 @@ domain socket ``vhost-user-blk.sock``::
--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
+Export a qcow2 image file ``disk.qcow2`` via FUSE on itself, so the disk image
+file will then appear as a raw image::
+
+ $ qemu-storage-daemon \
+ --blockdev driver=file,node-name=file,filename=disk.qcow2 \
+ --blockdev driver=qcow2,node-name=qcow2,file=file \
+ --export type=fuse,id=export,node-name=qcow2,mountpoint=disk.qcow2,writable=on
+
See also
--------