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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 <liam.merwick@oracle.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>pull/88/head
Stefan Hajnoczi
7 years ago
committed by
Dr. David Alan Gilbert
Dr. David Alan Gilbert
5 changed files with 134 additions and 2 deletions
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QEMU virtio-fs shared file system daemon |
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======================================== |
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Synopsis |
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-------- |
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**virtiofsd** [*OPTIONS*] |
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Description |
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----------- |
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Share a host directory tree with a guest through a virtio-fs device. This |
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program is a vhost-user backend that implements the virtio-fs device. Each |
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virtio-fs device instance requires its own virtiofsd process. |
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This program is designed to work with QEMU's ``--device vhost-user-fs-pci`` |
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but should work with any virtual machine monitor (VMM) that supports |
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vhost-user. See the Examples section below. |
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This program must be run as the root user. Upon startup the program will |
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switch into a new file system namespace with the shared directory tree as its |
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root. This prevents "file system escapes" due to symlinks and other file |
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system objects that might lead to files outside the shared directory. The |
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program also sandboxes itself using seccomp(2) to prevent ptrace(2) and other |
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vectors that could allow an attacker to compromise the system after gaining |
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control of the virtiofsd process. |
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Options |
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------- |
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.. program:: virtiofsd |
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.. option:: -h, --help |
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Print help. |
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.. option:: -V, --version |
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Print version. |
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.. option:: -d |
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Enable debug output. |
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.. option:: --syslog |
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Print log messages to syslog instead of stderr. |
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.. option:: -o OPTION |
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* debug - |
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Enable debug output. |
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* flock|no_flock - |
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Enable/disable flock. The default is ``no_flock``. |
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* log_level=LEVEL - |
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Print only log messages matching LEVEL or more severe. LEVEL is one of |
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``err``, ``warn``, ``info``, or ``debug``. The default is ``info``. |
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* norace - |
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Disable racy fallback. The default is false. |
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* posix_lock|no_posix_lock - |
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Enable/disable remote POSIX locks. The default is ``posix_lock``. |
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* readdirplus|no_readdirplus - |
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Enable/disable readdirplus. The default is ``readdirplus``. |
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* source=PATH - |
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Share host directory tree located at PATH. This option is required. |
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* timeout=TIMEOUT - |
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I/O timeout in seconds. The default depends on cache= option. |
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* writeback|no_writeback - |
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Enable/disable writeback cache. The cache alows the FUSE client to buffer |
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and merge write requests. The default is ``no_writeback``. |
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* xattr|no_xattr - |
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Enable/disable extended attributes (xattr) on files and directories. The |
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default is ``no_xattr``. |
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.. option:: --socket-path=PATH |
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Listen on vhost-user UNIX domain socket at PATH. |
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.. option:: --fd=FDNUM |
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Accept connections from vhost-user UNIX domain socket file descriptor FDNUM. |
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The file descriptor must already be listening for connections. |
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.. option:: --thread-pool-size=NUM |
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Restrict the number of worker threads per request queue to NUM. The default |
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is 64. |
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.. option:: --cache=none|auto|always |
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Select the desired trade-off between coherency and performance. ``none`` |
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forbids the FUSE client from caching to achieve best coherency at the cost of |
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performance. ``auto`` acts similar to NFS with a 1 second metadata cache |
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timeout. ``always`` sets a long cache lifetime at the expense of coherency. |
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Examples |
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-------- |
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Export ``/var/lib/fs/vm001/`` on vhost-user UNIX domain socket |
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``/var/run/vm001-vhost-fs.sock``: |
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:: |
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host# virtiofsd --socket-path=/var/run/vm001-vhost-fs.sock -o source=/var/lib/fs/vm001 |
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host# qemu-system-x86_64 \ |
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-chardev socket,id=char0,path=/var/run/vm001-vhost-fs.sock \ |
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-device vhost-user-fs-pci,chardev=char0,tag=myfs \ |
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-object memory-backend-memfd,id=mem,size=4G,share=on \ |
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-numa node,memdev=mem \ |
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... |
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guest# mount -t virtiofs myfs /mnt |
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