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Google Summer of Code Generic file system mounting project
Generic file system mounting introduction
File systems have their own "proprietary" mount protocol. Those protocols are defined as opaque containers called struct <fs>_args which contain different things from one file system to another. These need to be treated differently, as each addition of a file system implies adding specific code on every program which wants to use it.
The aim of this project is to replace them by a generic protocol, which could be used for every file system. Doing so, it could be possible for instance to mount a device without having to specify the file system type. To do this, I am using a prop_dictionary instead of the struct <fs>_args.
Deliverables
Mandatory (must-have) components:
- mount_generic command
- patches for in-tree file systems
- patch to add a new vfs operation
- up-to-date manpages
Status
A proof of concept has been written.
It contains the conversion of some file systems so as to use a properties dictionary, the new vfs_probe function and some applications which use them.
It was tested with rump(3) which allows to do the tests without having to rebuild a kernel and to debug as easily as if it were a userland application.
I converted fs-utils applications to make them use rump syscalls instead of the ukfs library. Then I wrote a new mounting library which uses the properties library. This library will be used to write the mount_generic program.
The code of these applications, the patch of the file systems and the vfs layer are available here.
Remaining work
- Asking on tech-kern for comments
- Adding support for remaining file systems
- Completing the mount_generic command
How to test it
Building the patched rump :
# cd /usr/src/sys # patch < ~/genfsmount.patch # cd rump # make && make installBuilding fs-utils libraries and applications :
# cd fsu_rsprop/lib # make includes # cd .. # make && make install
Examples
Usage
$ fsu_ls -o ro -w ffs.xml ~/ffs.img
Trying ffs: probing success, mount succeed
CVS Makefile.rump TODO include net
Makefile README.dirs fs librump
$ cat ffs.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>fspec</key>
<string>/home/stacktic/ffs.img</string>
</dict>
</plist>
$ fsu_cat -f ffs.xml Makefile
Trying ffs: probing success, mount succeed
# $NetBSD: Makefile,v 1.4 2008/11/17 10:21:44 pooka Exp $
#
SUBDIR= include librump fs net
.include <bsd.subdir.mk>
$ fsu_ls -o ro ~/i386cd.iso
Trying ffs: probing failed (22)
Trying cd9660: probing success, mount succeed
bin dev lib mnt2 stand sysinstmsgs.es targetroot
boot etc libexec netbsd sysinst sysinstmsgs.fr tmp
boot.cfg i386 mnt sbin sysinstmsgs.de sysinstmsgs.pl usr
Using specific options
$ fsu_ls ~/msdos.img Trying ffs: probing failed (22) Trying cd9660: probing failed (22) Trying msdos: probing succeeded, mount succeeded CVS Makefile.rump TODO include net Makefile README.dirs fs librump $ fsu_ls -s shortname,uid=stacktic,gid=users ~/msdos.img -l Adding: shortname = true Adding: uid = 1000 Adding: gid = 100 Trying ffs: probing failed (22) Trying cd9660: probing failed (22) Trying msdos: probing succeeded, mount succeeded total 288 d--------- 1 stacktic users 16384 Jun 12 11:30 cvs d--------- 1 stacktic users 16384 Jun 12 11:30 fs d--------- 1 stacktic users 16384 Jun 12 11:30 include d--------- 1 stacktic users 16384 Jun 12 11:30 librump ---------- 1 stacktic users 118 Jun 12 11:30 makefile ---------- 1 stacktic users 2377 Jun 12 11:30 makefi~1.rum d--------- 1 stacktic users 16384 Jun 12 11:30 net ---------- 1 stacktic users 1525 Jun 12 11:30 readme~1.dir ---------- 1 stacktic users 530 Jun 12 11:30 todo
Links
- Project description on NetBSD SoC project list
- Project on GSoC page
- Project on NetBSD SoC sourceforge page