FUSEFS(5)                 FreeBSD File Formats Manual                FUSEFS(5)

NAME
     fusefs - File system in USErspace

SYNOPSIS
     To link into the kernel:

           options FUSEFS

     To load as a loadable kernel module:

           kldload fusefs

DESCRIPTION
     The fusefs driver implements a file system that is serviced by a
     userspace program.

     There are many uses for fusefs.  Userspace daemons can access libraries
     or programming languages that cannot run in kernel-mode, for example.
     fusefs is also useful for developing and debugging file systems, because
     a crash of the daemon will not take down the entire operating system.
     Finally, the fusefs API is portable.  Many daemons can run on multiple
     operating systems with minimal modifications.

SYSCTL VARIABLES
     The following sysctl(8) variables are available:

     vfs.fusefs.kernelabi_major
             Major version of the FUSE kernel ABI supported by this driver.

     vfs.fusefs.kernelabi_minor
             Minor version of the FUSE kernel ABI supported by this driver.

     vfs.fusefs.data_cache_mode
             Controls how fusefs will cache file data for pre-7.23 file
             systems.  A value of 0 will disable caching entirely.  Every data
             access will be forwarded to the daemon.  A value of 1 will select
             write-through caching.  Reads will be cached in the VFS layer as
             usual.  Writes will be immediately forwarded to the daemon, and
             also added to the cache.  A value of 2 will select write-back
             caching.  Reads and writes will both be cached, and writes will
             occasionally be flushed to the daemon by the page daemon.  Write-
             back caching is usually unsafe, especially for FUSE file systems
             that require network access.

             FUSE file systems using protocol 7.23 or later specify their
             cache behavior on a per-mountpoint basis, ignoring this sysctl.

     vfs.fusefs.stats.filehandle_count
             Current number of open FUSE file handles.

     vfs.fusefs.stats.lookup_cache_hits
             Total number of lookup cache hits.

     vfs.fusefs.stats.lookup_cache_misses
             Total number of lookup cache misses.

     vfs.fusefs.stats.node_count
             Current number of allocated FUSE vnodes.

     vfs.fusefs.stats.ticket_count
             Current number of allocated FUSE tickets, which is roughly equal
             to the number of FUSE operations currently being processed by
             daemons.

SEE ALSO
     mount_fusefs(8)

HISTORY
     The fuse driver was written as the part of the FreeBSD implementation of
     the FUSE userspace file system framework (see
     https://github.com/libfuse/libfuse) and first appeared in the
     sysutils/fusefs-kmod port, supporting FreeBSD 6.0.  It was added to the
     base system in FreeBSD 10.0, and renamed to fusefs for FreeBSD 12.1.

AUTHORS
     The fuse driver was originally written by Csaba Henk as a Google Summer
     of Code project in 2005.  It was further developed by Ilya Putsikau
     during Google Summer of Code 2011, and that version was integrated into
     the base system by Attilio Rao <attilio@FreeBSD.org>.

     This manual page was written by Alan Somers <asomers@FreeBSD.org>.

FreeBSD 13.1-RELEASE-p6          July 31, 2019         FreeBSD 13.1-RELEASE-p6