NAME

       fuse-overlayfs - overlayfs FUSE implementation

SYNOPSIS

       mounting
           fuse-overlayfs [-f] [--debug] [-o OPTS] MOUNT_TARGET

       unmounting
           fusermount -u mountpoint

DESCRIPTION

       fuse-overlayfs  provides  an  overlayfs  FUSE  implementation so that it can be used since
       Linux 4.18 by unprivileged users in an user namespace.

OPTIONS

       --debug Enable debugging mode, can be very noisy.

       -o lowerdir=low1[:low2...]  A list of  directories  separated  by  :.   Their  content  is
       merged.

       -o  upperdir=upperdir A directory merged on top of all the lowerdirs where all the changes
       done to the file system will be written.

       -o workdir=workdir A directory used internally by fuse-overlays, must be on the same  file
       system as the upper dir.

       -o    uidmapping=UID:MAPPED-UID:LEN[,UID2:MAPPED-UID2:LEN2]    -o   gidmapping=GID:MAPPED-
       GID:LEN[,GID2:MAPPED-GID2:LEN2] Specifies  the  dynamic  UID/GID  mapping  used  by  fuse-
       overlayfs when reading/writing files to the system.

       The  fuse-overlayfs  dynamic  mapping  is  an alternative and cheaper way to chown'ing the
       files on the host to accommodate the user namespace settings.

       It is useful to share the same storage among different user namespaces and counter  effect
       the mapping done by the user namespace itself, and without requiring to chown the files.

       For example, given on the host two files like:

       $ stat -c %u:%g lower/a lower/b 0:0 1:1

       When we run in a user namespace with the following configuration: $ cat /proc/self/uid_map
                0       1000          1
                1     110000      65536

       We would see:

       $ stat -c %u:%g merged/a merged/b 65534:65534 65534:65534

       65534  is  the  overflow  id used when the UID/GID is not known inside the user namespace.
       This happens because both users 0:0 and 1:1 are not mapped.

       In  the  above  example,   if   we   mount   the   fuse-overlayfs   file   system   using:
       -ouidmapping=0:1000:1:1:110000:65536,gidmapping=0:1000:1:1:110000:65536,   which   is  the
       namespace configuration specified on a single line, we'd see from the same user namespace:

       $ stat -c %u:%g merged/a merged/b 0:0 1:1

       Those are the same IDs visible from outside the user namespace.

       -o squash_to_root Every file and directory is owned by the root user (0:0).

       -o squash_to_uid=uid -o squash_to_gid=gid  Every  file  and  directory  is  owned  by  the
       specified uid or gid.

       It has higher precedence over squash_to_root.

       -o static_nlink Set st_nlink to the static value 1 for all directories.

       This  can be useful for higher latency file systems such as NFS, where counting the number
       of hard links for a directory with many files can be a slow operation.  With  this  option
       enabled, the number of hard links reported when running stat for any directory is 1.

       -o noacl Disable ACL support in the FUSE file system.

SEE ALSO

       fuse(8), mount(8), user_namespaces(7)

AVAILABILITY

       The  fuse-overlayfs command is available from https://github.com/containers/fuse-overlayfs
       under GNU GENERAL PUBLIC LICENSE Version 3 or later.

                                          User Commands                         fuse-overlayfs(1)