Date: Tue, 17 Mar 1998 02:27:41 -0500 (EST) From: "John S. Dyson" <dyson@FreeBSD.ORG> To: michaelh@cet.co.jp (Michael Hancock) Cc: karl@mcs.net, root@danberlin.resnet.rochester.edu, current@FreeBSD.ORG, dyson@FreeBSD.ORG Subject: Re: WARNING WILL ROBINSON! Risk of severe filesystem damage suspected Message-ID: <199803170727.CAA11562@dyson.iquest.net> In-Reply-To: <Pine.SV4.3.95.980317155553.9759A-100000@parkplace.cet.co.jp> from Michael Hancock at "Mar 17, 98 03:57:39 pm"
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The code as-is is correct. All of the evil was in vfs_subr.c:vtruncbuf.
The vtruncbuf change was needed for some VM/buffer cache coherency problems,
and unfortunately it didn't sync out metadata, when the rest of the upper
level FFS code expected it to. After a while, the filesystem would
irrecoverably loose it's mind. I lost 4 filesystems over this problem,
and spent hours trying to recover the system and fix the problem.
Michael Hancock said:
> John,
>
> Is this what you meant?
>
> Mike
>
> Index: vfs_bio.c
> ===================================================================
> RCS file: /usr/cvs/src/sys/kern/vfs_bio.c,v
> retrieving revision 1.156
> diff -u -r1.156 vfs_bio.c
> --- vfs_bio.c 1998/03/16 01:55:22 1.156
> +++ vfs_bio.c 1998/03/17 06:03:47
> @@ -676,7 +676,7 @@
> break;
> }
> if (bp->b_flags & (B_NOCACHE|B_ERROR)) {
> - int poffset = foff & PAGE_MASK;
> + int poffset = poff & PAGE_MASK;
> int presid = resid > (PAGE_SIZE - poffset) ?
> (PAGE_SIZE - poffset) : resid;
> vm_page_set_invalid(m, poffset, presid);
>
>
--
John | Never try to teach a pig to sing,
dyson@freebsd.org | it just makes you look stupid,
jdyson@nc.com | and it irritates the pig.
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