NAME
translucency - overlays file-systems
SYNOPSIS
insmod translucency
echo "/layer/1 -> /layer/2" > /proc/sys/translucency/0
# alternatively, use mount.translucency
echo 65534 > /proc/sys/translucency/uid
echo 16 > /proc/sys/translucency/flags
DESCRIPTION
translucency will install modified syscall handlers that redirect file operations in such a way as to logically merge several directories (presumably on different file-systems, on different media) into one directory.
OPTIONS
Options can no longer be given at module loading time. Instead they have to be written into the appropriate /proc/sys/translucency/<option> file.
- [0-9]*
-
are overlay entries used as seen above: /layer/1 is lower layer - write access is redirected away. /layer/2 is upper layer - written files go here
- uid=<int>
-
limits overlaying to user with EUID <int>
- gid=<int>
-
limits overlaying to group with EGID <int>
- fs=<int>
-
limits overlaying of mounts to filesystems with this magic number <int> ; negative values mean all except the given one ; for values see grep SUPER_MAGIC /usr/include/linux/*.h
- flags=<int>
-
change the module's operation with a bitwise combination of the following:
- 1=no_translucency:
-
turns module off
- 2=no_copyonwrite:
-
kernel does not try to copy files if needed (i.e. for appending)
- 4=no_getdents:
-
turn off merging directories - only entries in lower layer are shown in directory listings
- 8=do_downcase:
-
downcase all filenames to avoid inconsistencies on case-insensitive filesystems
- 16=no_whiteout:
-
do not automatically create whiteout entries which allow for renaming and deletion of files on r/o filesystems
NOTES
This version requires /tmp to be writeable.
KNOWN BUGS
Bad symlink handling
Bad .. handling after chdir into a dir that only exists in overlay
rmdir and rm -r are often not able to remove a directory stating that is not empty (it contains white-out entries)
There are probably serious buffer overflow conditions left in this module. Suggestions for improving the security of this module are welcome!
BUGS
Report bugs through the bug-tracking system at http://sourceforge.net/projects/translucency/
AUTHOR
Bernhard M. Wiedemann <[email protected]>
David Bird <[email protected]>
SEE ALSO
The effect is somewhat similar to: inheriting (ifs), stacking (fist), translucent (tfs), loopback (lofs), overlaying (ovlfs), and BSDs union file system
VERSION
This manual page applies to translucency 0.6.0