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[PULL 7/9] qsd: Document FUSE exports
From: |
Max Reitz |
Subject: |
[PULL 7/9] qsd: Document FUSE exports |
Date: |
Tue, 30 Mar 2021 14:39:55 +0200 |
Implementing FUSE exports required no changes to the storage daemon, so
we forgot to document them there. Considering that both NBD and
vhost-user-blk exports are documented in its man page (and NBD exports
in its --help text), we should probably do the same for FUSE.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210217115844.62661-1-mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
---
docs/tools/qemu-storage-daemon.rst | 19 +++++++++++++++++++
storage-daemon/qemu-storage-daemon.c | 4 ++++
2 files changed, 23 insertions(+)
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
--------
diff --git a/storage-daemon/qemu-storage-daemon.c
b/storage-daemon/qemu-storage-daemon.c
index 72900dc2ec..fc8b150629 100644
--- a/storage-daemon/qemu-storage-daemon.c
+++ b/storage-daemon/qemu-storage-daemon.c
@@ -98,6 +98,10 @@ static void help(void)
" export the specified block node over NBD\n"
" (requires --nbd-server)\n"
"\n"
+" --export [type=]fuse,id=<id>,node-name=<node-name>,mountpoint=<file>\n"
+" [,growable=on|off][,writable=on|off]\n"
+" export the specified block node over FUSE\n"
+"\n"
" --monitor [chardev=]name[,mode=control][,pretty[=on|off]]\n"
" configure a QMP monitor\n"
"\n"
--
2.29.2
- [PULL 0/9] Block patches for 6.0-rc1, Max Reitz, 2021/03/30
- [PULL 1/9] iotests: Fix typo in iotest 051, Max Reitz, 2021/03/30
- [PULL 2/9] iotests: fix 051.out expected output after error text touchups, Max Reitz, 2021/03/30
- [PULL 3/9] iotests/116: Fix reference output, Max Reitz, 2021/03/30
- [PULL 4/9] qcow2: use external virtual timers, Max Reitz, 2021/03/30
- [PULL 5/9] iotests/046: Filter request length, Max Reitz, 2021/03/30
- [PULL 8/9] qcow2: Force preallocation with data-file-raw, Max Reitz, 2021/03/30
- [PULL 9/9] iotests/244: Test preallocation for data-file-raw, Max Reitz, 2021/03/30
- [PULL 6/9] block/mirror: Fix mirror_top's permissions, Max Reitz, 2021/03/30
- [PULL 7/9] qsd: Document FUSE exports,
Max Reitz <=
- Re: [PULL 0/9] Block patches for 6.0-rc1, Peter Maydell, 2021/03/30