Messages in this thread | | | Date | Thu, 13 Dec 2001 09:52:55 -0600 (CST) | From | <> | Subject | Re: passing params to boot readonly |
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On Thu, 13 Dec 2001, Hans Reiser wrote:
> Ryan Cumming wrote: > > >On December 12, 2001 21:50, Stewart Allen wrote: > > > >>I'm in a bit of a pickle and need to find a way to pass boot params to a > >>reiserfs rootfs to *prevent* it from replaying the journal on single-user > >>boot. This may seem like a strange request, but I've got a degraded RAID > >>array that I need to poke around in before deciding whether or not to send > >>a disk off to a rehab lab. If the replay occurs, it will potentially > >>destroy the fs since I'm using a degraded snapshot of the failed disk in > >>hopes of reclaiming *some* of my data. The system is running 2.2.x (can't > >>remember and can't find out w/out booting). > >> > >>Do I have a snowball's chance of pulling this off? > >> > > > >Well, kinda. The only thing that can deter ReiserFS from replaying the > >journal is convincing it that the physical media it's on is actually read > >only. Some quick less/grep work revealed that there is no option that makes > >the SCSI subsystem claim its devices are readonly (although it'd be extremely > >useful for situations such as this). > > > >It'd probably be pretty easy to make a boot disk using a hacked version of > >ReiserFS that refuses to replay the journal, by adding a "return 0;" near the > >top of journal_read(struct super_block *) in journal.c. However, you might > >feel more comfortable sending it off for data recovery than testing kernel > >hacks on it ;) > > > >-Ryan > >- > >To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > >the body of a message to majordomo@vger.kernel.org > >More majordomo info at http://vger.kernel.org/majordomo-info.html > >Please read the FAQ at http://www.tux.org/lkml/ > > > > > why not just edit the source code directly and recompile? > > Hans
There are a couple of potential problems with this approach:
1. I thought the on-disk structures for ReiserFS changed sometime between 2.2.something (the system in question) and now. Since I cannot pinpoint the kernel/patch version, I'm not sure this hack will work.
2. I have no other systems like this one to test the read-only hack on. Without a fairly high degree of confidence that I'm actually booting in a no-replay read-only state, I'm not going to take chances with this data.
stewart
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