Date: Tue, 28 Mar 2000 09:20:55 -0500 (EST) From: Kenneth W Cochran <kwc@world.std.com> To: "Mark W. Krentel" <krentel@dreamscape.com> Cc: freebsd-fs@freebsd.org Subject: Re: ext2fs optional features Message-ID: <200003281420.JAA18752@world.std.com>
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>From krentel@dreamscape.com Mon Mar 27 15:13:54 2000 >Date: Mon, 27 Mar 2000 15:09:27 -0500 (EST) >Subject: Re: ext2fs optional features > >> Hmmm, which distribution/kernel version? > >For me, Red Hat 6.1 and kernel 2.2.12, but you'll get the same >answer with Slackware 7. The key attributes are: > > Filesystem revision #: 1 (dynamic) > Filesystem features: sparse_super > >You'll need a filesystem without sparse_super and probably >revision 0. > >> Is there a way, perhaps in Linux with its tunefs, to adjust or >> "turn off" those "optional features" (other things too?) in such >> a way that FreeBSD's ext2 support will work? > >As a workaround, you can boot a Linux live filesystem or rescue >disk and manually run mke2fs as: > > # mke2fs -r0 -s0 /dev/whatever > >Then reinstall Linux, telling it to NOT reformat the partitions. >Of course, this will erase any data on the partition, so you'll >have to either dump or tar the filesystem or else reinstall from >scratch. I don't think you can turn off these features without >remaking the partition. > >But I think the real answer to Kenneth's and my question is that >Freebsd doesn't support these optional features and isn't likely to >in the near future. Can anyone offer a more optimistic outlook? > >--Mark Krentel This is an edited diff-list from "tune2fs -l" on 2 Linux ext2 filesystems I have; the "old" one works r/w with FreeBSD's ext2 support (I believe it was made with Slackware 4.0), the "new" one (made with Slackware 7.0) only works readonly. OSes are FreeBSD 3.4-stable, as of 2000/03/28 & Slackware Linux 7.0 with kernel 2.2.14. I deleted what appeared to be non-relevant things (inode counts, etc...) tune2fs 1.15, 18-Jul-1999 for EXT2 FS 0.5b, 95/08/09 4c4 < Filesystem UUID: <none> --- > Filesystem UUID: 256642ba-cff5-11d3-949e-8f1d32744825 6,8c6,8 < Filesystem revision #: 0 (original) < Filesystem features: (none) < Filesystem state: clean --- > Filesystem revision #: 1 (dynamic) > Filesystem features: sparse_super > Filesystem state: not clean As Mark has mentioned, I'm guessing that the critical pieces are the Filesystem revision # & the Filesystem features. According to the Linux tune2fs manpage, the "features" (ie. sparse_super) can be toggled with tune2fs. (No, I have *not* tried it... Too afraid... :) No mention is made, though, of the revision #, so I'd bet that must be & is set at filesystem creation. :/ What I'm Looking For... A way to share data between dual-booting FreeBSD & Linux. So far, the best way I've found (YMMV :) is via FreeBSD's ext2 support. My experience with Linux's ufs support has been Very Very Bad. With Linux "migrating" toware its new "ext3" filesystem, it would seem to me that the most appropriate way for this kind of "sharing" would be to create a "buffer filesystem" as ext2 version 0 with no special features... And, of course, I would think this to make a good addition to FreeBSD FAQs & docs. :) -kc To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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