The goal of this assignment is to create a user-level networked file system
Download and install FUSE. Write a simple networked file system. During the mount, you should specify the remote server name. Use a different physical machine for client and server. Make sure the remote system is one to which you can ssh. Whenever you get a request for a file, copy the entire file (using scp or sftp or libssh, hence the need for ssh access) from the remote server and cache it in /tmp or /var/tmp, then service the requests locally. Copy modified files back when the file is closed. You may use rcp or another alternative to scp for the file transfer.
Compare your file system to NFS. Design an experiment that shows the performance advantage and disadvantage of this scheme relative to NFS. We believe that you can find some scenario where your FS is significantly faster than NFS, and some other scenario where NFS is significantly faster. Therefore, it's fine to use different setups for NFS and your FUSE fs. Your writeup should contain at least one graph, but probably more.
Explain what FUSE calls you implement, and what you do for each call
Make sure your implementation can run the following program properly. It is most useful if foo exists. You should write and read the same number of bytes.
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <assert.h>
int
main() {
int fd0 = open("foo", O_RDWR);
int fd1 = open("foo", O_RDONLY);
char buf[100];
buf[0] = 9;
buf[1] = 81;
buf[2] = 'A';
buf[3] = 'q';
buf[4] = '0';
int nb0 = write(fd0, buf, 100);
int nb1;
close(fd0);
nb1 = read(fd1, buf, 100);
assert(buf[0] == 9);
assert(buf[1] == 81);
assert(buf[2] == 'A');
assert(buf[3] == 'q');
assert(buf[4] == '0');
close(fd1);
printf("Wrote %d, then %d bytes\n", nb0, nb1);
return 0;
}
Please report how much time you spent on the lab.
A LaTeX template that includes placeholders for materials required in your writeup and re-iterates any questions we expect answers for can be found here, (a build of that template is here). Many thanks to Jo Bridgwater for creating the template, and for its homage to Monty Python.
Hints
If you use ssh/scp, you probably want to put your public key in your authorized_keys file or run ssh-agent so you aren't prompted for a password on every file system transaction.
You can use stat on the server to implement getattr, but you might want to consider a helper program to simplify parsing.
Here are some links that explain FUSE and even provide sample code.
http://www.cs.nmsu.edu/~pfeiffer/fuse-tutorial/
https://www.cs.hmc.edu/~geoff/classes/hmc.cs135.201001/homework/fuse/fuse_doc.html
If you don't have two machines under your control, we suggest you to use 2 CS machines:
script session_record
strace cat - > new_file
hi mom
^Dexit
lsof | grep /dev
ifconfig to figure out the name of the interface your machine is using to communicate externally (from now on this interface will be referred to as <eth0>).tcpdump to start recording packets on <eth0> and write them to a file (<packetfile>). sudo dhclient -r to release your machine's current DHCP lease. sudo dhclient <eth0>, and once this command completes stop recording packets. (You can repeat the process of releasing and reacquiring an address a few times if you would like.)tcpdump to inspect the packets you have recorded in <packetfile> (if you have trouble recording the packets from your system we have also provided this file: tcpdump.out) and answer the following questions: