KFS(4) KFS(4)
NAME
kfs - disk file system
SYNOPSIS
mount {disk/kfs [-r [ -b bsize ] ] [-c] [-A] [-P] [-R] [-W]
[ -n name ] file} dir
DESCRIPTION
Kfs implements a hierarchical Inferno file system within an
existing file, which is typically a disk or flash memory
partition. It gives access to it through the 9P protocol on
its standard input, and the contents can be mounted directly
on a given dir as shown above. The file system format is
the same as that used by the kfs command of Plan 9, except
that the modification user ID is implemented.
The -r option causes the file system to be reset to an ini-
tially empty state (`reamed'). Permission checking is
turned off, to allow any desired permissions and file owner-
ship to be set. (In other words, the -W and -P options are
also set by default.) The file system block size is set to
the bsize given by the -b option (default: 1024 bytes),
which must be a multiple of 512 and not greater than 16k
bytes. The block size is stored in the file and need not be
given again. The storage representation is always little-
endian.
Otherwise, the file system is checked if required, unless
the -c option is given.
The contents of the file system can be provided by using
commands such as mkdir(1), cp(1) and rm(1) in dir, or built
from a description using mkfs(8).
The mapping between user names and internal IDs within the
file system is established by the file adm/users (within the
file system itself) as described by users(6), which kfs
reads when it starts. If no such file exists, as for
instance when the file system is initially empty, kfs uses a
minimal set corresponding to the following users(6) file:
-1:adm:adm:
0:none:adm:
9999:noworld::
10000:sys::
10001:upas:upas:
10002:bootes:bootes:
10006:inferno::
Any users(6) file used with kfs should include entries for
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KFS(4) KFS(4)
at least adm, none, and noworld as above (although group
membership can vary).
Kfs can optionally serve a control file, for use by
kfscmd(8). If the -n option is given, kfs creates a channel
/chan/kfs.name.cmd and accepts commands on it from the user
that started kfs.
Other options are:
-A do not update access times; useful when running a file
system in flash over ftl(3), to avoid excessive wear
-P suppress permission checking
-R file system is read only
-W allow wstat (see sys-stat(2) or stat(5)) to make arbi-
trary changes to user and group fields
EXAMPLES
Create an empty file system in the file kfs.file. Because
the file system will be no larger than the existing file's
size, and the file is assumed not to be a device file, use
zeros(1) to prepare a file with 2048 blocks of 1024 bytes
each:
zeros 1024 2048 >kfs.file
mount -c {disk/kfs -r kfs.file} /n/local
The -c option to mount allows files to be created in
/n/local.
SOURCE
/appl/cmd/disk/kfs.b
SEE ALSO
dd(1), zeros(1), flash(3), ftl(3), logfs(3), sd(3),
users(6), kfscmd(8), mkfs(8)
BUGS
Because the file system format is the same as Plan 9's kfs,
this one also does not support file names longer than 27
bytes. It likewise cannot cope with files bigger than 2ⁱ-1
bytes.
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