Re: [PATCH] IFS: Inode FileSystem

Are there any real users of this FS? If my memory serves,
Adrian's plan was to add IFS support into the squid. I
wonder if it had happened and whether or not it actually
provides any real performance benefit.

-Maxim

On Sun, Jun 05, 2005 at 02:03:10PM -0400, Suleiman Souhlal wrote:
> Hi,
> 
> IFS is basically FFS, minus the namespace. Files are referenced by  
> their inode number, thus making file lookup very fast. This is very  
> useful for things that keep the file names in their own database  
> anyway, such as web or news caches.
> 
> Files are created by opening the "newfile" file:
> 
>     fd = open("newfile", O_CREAT|O_RDWR, 0644);
>     fstat(fd, &st);
>     printf("new file is %d\n", (int)st.st_ino);
> 
> Once a file has been created it is possible to accessing by just  
> opening it the file named after the inode number. For example:
> 
>     fd = open("5", O_RDWR);
> 
> This filesystem was imported back in the year 2000, by Adrian Chadd  
> (adrian_at_) and removed in 2002, before the introduction of UFS2 in  
> order not to slow down the development of UFS2.
> 
> I have fixed it so that it is usable on -CURRENT. You can find the  
> kernel bits at http://people.freebsd.org/~ssouhlal/testing/ 
> ifs-20050605-2.diff and the userland bits at http:// 
> people.freebsd.org/~ssouhlal/testing/ifs-20050605-userland-2.diff .
> (You need to copy src/sbin/fsck_ffs to src/sbin/fsck_ifs and src/sbin/ 
> mount_ufs to src/sbin/mount_ifs, before applying the userland patch).
> 
> You can use the regular newfs(8) to create such a filesystem. You  
> might also want to specify the -n option, so that the .snap directory  
> is not created at newfs, since directories are useless, in IFS. If  
> you don't you'll end up with a useless inode, which is not really a  
> big deal.
> Once the filesystem is created, you can mount it with mount_ifs.
> 
> You can find additional comments in src/sys/ufs/ifs/README in the patch.
> 
> Is anyone interested in seeing this committed?
> 
> Bye,
> --
> Suleiman Souhlal     | ssouhlal_at_vt.edu
> The FreeBSD Project  | ssouhlal_at_FreeBSD.org
> 
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