shithub: riscv

ref: 3d5dca521797b5a91ebc4281fbaf58211bb4f40f
dir: /sys/man/4/ext4srv/

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.TH EXT4SRV 4
.SH NAME
ext4srv \- ext4 file system
.SH SYNOPSIS
.B ext4srv
[
.B -Crs
] [
.B -g
.I groupfile
] [
.B -R
.I uid
] [
.I service
]
.PP
.B ext4srv
.B -M
.I (2|3|4)
[
.B -L
.I label
] [
.B -b
.I blksize
] [
.B -N
.I numinodes
] [
.B -I
.I inodesize
]
.I device
.SH DESCRIPTION
.I Ext4srv
is a file server that interprets the Linux Second, Third and Fourth
Extended File Systems.
A single instance of
.I ext4srv
can provide access to multiple ext2, ext3 and ext4 partitions
simultaneously.
.PP
.I Ext4srv
posts a file descriptor named
.I service
(default
.BR ext4 )
in the
.B /srv
directory.
To access an ext4 file system on a device, use
.B mount
with the
.I spec
argument
(see
.IR bind (1))
the name of the file holding the raw ext4 file system, typically the disk or partition.
If
.I spec
is undefined in the
.BR mount ,
.I ext4srv
will use
.I file
as the default name for the device holding the file system.
.PP
Normally
.I ext4srv
creates a pipe to act as the communications channel between
itself and its clients.
The
.B -s
flag instructs
.I ext4srv
to use its standard input and output instead.
This flag also prevents the creation of an explicit service file in
.BR /srv .
.PP
The
.B -r
flag (recommended) makes the file system read-only.
The optional
.B -g
flags specify Unix-format group file that give the mapping between the
numeric user- and group-ID numbers in the ext4 file system and the
strings reported by Plan 9 status inquiries.
.PP
With
.B -R
option the filesystem can be mounted in "root" mode, allowing full access regardless
of permissions. The usual
.I uid
in this case is
.IR 0 .
.PP
Some file system state is cached in memory, and may
be flushed only when the file system is unmounted if
.B -C
flag is used, which enabled write-back cache.
Therefore if
.I ext4srv
is stopped or the machine is rebooted while an ext4 file system is
still mounted, the superblock on the device will have been marked `not
valid'
(unless the
.B -r
flag was used).
.SH MKFS
A different mode of
.I ext4srv
is enabled with
.B -M
option that accepts the file system version
.RI ( 2
for
.I ext2
and so on).
In this mode filesystem is initialized on the specified
.I device
and all existing data on it is destroyed.
.PP
Additional options may be specified, for example
.B -L
may be used to set the filesystem label.
.SH BUGS
Yes.
.PP
Permission checking is very basic and may not be complete.
Symlinks are not resolved.
There may be many bugs.
It is advisable to use
.I ext4srv
in read-only mode whenever possible.
.SH HISTORY
.I Ext4srv
first appeared in 9front (February, 2024).