Date: Mon, 6 Jun 2005 05:31:45 +0200 From: Maxim Sobolev <sobomax@portaone.com> To: Suleiman Souhlal <ssouhlal@FreeBSD.ORG> Cc: current@FreeBSD.ORG, fs@FreeBSD.ORG Subject: Re: [PATCH] IFS: Inode FileSystem Message-ID: <20050606033145.GA80739@www.portaone.com> In-Reply-To: <82ACAD58-B179-44E2-852F-60F25C0BBBC1@FreeBSD.org> References: <82ACAD58-B179-44E2-852F-60F25C0BBBC1@FreeBSD.org>
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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@) 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@vt.edu
> The FreeBSD Project | ssouhlal@FreeBSD.org
>
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