From 6a7e2bbee5fa5f167959f05319550d2a49a6b8bb Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Fri, 7 Feb 2020 16:29:51 +0000 Subject: docs: add virtiofsd(1) man page Document the virtiofsd(1) program and its command-line options. This man page is a rST conversion of the original texi documentation that I wrote. Reviewed-by: Liam Merwick Signed-off-by: Stefan Hajnoczi Reviewed-by: Dr. David Alan Gilbert Signed-off-by: Dr. David Alan Gilbert --- docs/interop/conf.py | 5 +- docs/interop/index.rst | 1 + docs/interop/virtiofsd.rst | 120 +++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 125 insertions(+), 1 deletion(-) create mode 100644 docs/interop/virtiofsd.rst (limited to 'docs/interop') diff --git a/docs/interop/conf.py b/docs/interop/conf.py index b0f322207c..b3cda17042 100644 --- a/docs/interop/conf.py +++ b/docs/interop/conf.py @@ -27,5 +27,8 @@ man_pages = [ [], 1), ('virtfs-proxy-helper', 'virtfs-proxy-helper', u'QEMU 9p virtfs proxy filesystem helper', - ['M. Mohan Kumar'], 1) + ['M. Mohan Kumar'], 1), + ('virtiofsd', 'virtiofsd', u'QEMU virtio-fs shared file system daemon', + ['Stefan Hajnoczi ', + 'Masayoshi Mizuma '], 1), ] diff --git a/docs/interop/index.rst b/docs/interop/index.rst index 3b763b1eeb..e8455b4270 100644 --- a/docs/interop/index.rst +++ b/docs/interop/index.rst @@ -24,3 +24,4 @@ Contents: vhost-user vhost-user-gpu virtfs-proxy-helper + virtiofsd diff --git a/docs/interop/virtiofsd.rst b/docs/interop/virtiofsd.rst new file mode 100644 index 0000000000..378594c422 --- /dev/null +++ b/docs/interop/virtiofsd.rst @@ -0,0 +1,120 @@ +QEMU virtio-fs shared file system daemon +======================================== + +Synopsis +-------- + +**virtiofsd** [*OPTIONS*] + +Description +----------- + +Share a host directory tree with a guest through a virtio-fs device. This +program is a vhost-user backend that implements the virtio-fs device. Each +virtio-fs device instance requires its own virtiofsd process. + +This program is designed to work with QEMU's ``--device vhost-user-fs-pci`` +but should work with any virtual machine monitor (VMM) that supports +vhost-user. See the Examples section below. + +This program must be run as the root user. Upon startup the program will +switch into a new file system namespace with the shared directory tree as its +root. This prevents "file system escapes" due to symlinks and other file +system objects that might lead to files outside the shared directory. The +program also sandboxes itself using seccomp(2) to prevent ptrace(2) and other +vectors that could allow an attacker to compromise the system after gaining +control of the virtiofsd process. + +Options +------- + +.. program:: virtiofsd + +.. option:: -h, --help + + Print help. + +.. option:: -V, --version + + Print version. + +.. option:: -d + + Enable debug output. + +.. option:: --syslog + + Print log messages to syslog instead of stderr. + +.. option:: -o OPTION + + * debug - + Enable debug output. + + * flock|no_flock - + Enable/disable flock. The default is ``no_flock``. + + * log_level=LEVEL - + Print only log messages matching LEVEL or more severe. LEVEL is one of + ``err``, ``warn``, ``info``, or ``debug``. The default is ``info``. + + * norace - + Disable racy fallback. The default is false. + + * posix_lock|no_posix_lock - + Enable/disable remote POSIX locks. The default is ``posix_lock``. + + * readdirplus|no_readdirplus - + Enable/disable readdirplus. The default is ``readdirplus``. + + * source=PATH - + Share host directory tree located at PATH. This option is required. + + * timeout=TIMEOUT - + I/O timeout in seconds. The default depends on cache= option. + + * writeback|no_writeback - + Enable/disable writeback cache. The cache alows the FUSE client to buffer + and merge write requests. The default is ``no_writeback``. + + * xattr|no_xattr - + Enable/disable extended attributes (xattr) on files and directories. The + default is ``no_xattr``. + +.. option:: --socket-path=PATH + + Listen on vhost-user UNIX domain socket at PATH. + +.. option:: --fd=FDNUM + + Accept connections from vhost-user UNIX domain socket file descriptor FDNUM. + The file descriptor must already be listening for connections. + +.. option:: --thread-pool-size=NUM + + Restrict the number of worker threads per request queue to NUM. The default + is 64. + +.. option:: --cache=none|auto|always + + Select the desired trade-off between coherency and performance. ``none`` + forbids the FUSE client from caching to achieve best coherency at the cost of + performance. ``auto`` acts similar to NFS with a 1 second metadata cache + timeout. ``always`` sets a long cache lifetime at the expense of coherency. + +Examples +-------- + +Export ``/var/lib/fs/vm001/`` on vhost-user UNIX domain socket +``/var/run/vm001-vhost-fs.sock``: + +:: + + host# virtiofsd --socket-path=/var/run/vm001-vhost-fs.sock -o source=/var/lib/fs/vm001 + host# qemu-system-x86_64 \ + -chardev socket,id=char0,path=/var/run/vm001-vhost-fs.sock \ + -device vhost-user-fs-pci,chardev=char0,tag=myfs \ + -object memory-backend-memfd,id=mem,size=4G,share=on \ + -numa node,memdev=mem \ + ... + guest# mount -t virtiofs myfs /mnt -- cgit v1.2.3-55-g7522