Date: Fri, 29 Mar 2002 14:34:51 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Danny Schales <dan@coes.LaTech.edu> Cc: Rolandas Naujikas <rolnas@takas.lt>, Bruce Campbell <bruce@engmail.uwaterloo.ca>, Doug White <dwhite@resnet.uoregon.edu>, Wilko Bulte <wkb@freebie.xs4all.nl>, "Paul Horechuk" <phorechuk@docucom.ca>, stable@FreeBSD.ORG Subject: Re: nfs_fsync: not dirty error in 4.5-RELEASE (possible solution) Message-ID: <200203292234.g2TMYpq67679@apollo.backplane.com>
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Ok, I am putting this back on the main list.
After looking at a kernel core that Danny graciously provided, I believe
I have located the problem.
The core shows NFS panicing on a struct buf showing up on the vnode's
v_dirtyblkhd list that is not marked B_DELWRI.
After examining the core I found that the buffer was marked B_INVAL,
and I found a case in brelse() where B_DELWRI is cleared on a buffer
marked B_DELWRI|B_INVAL without moving it out of the vnode's v_dirtyblkhd
list. Specifically, line 1214 if kern/vfs_bio.c:
/*
* If B_INVAL, clear B_DELWRI. We've already placed the buffer
* on the correct queue.
*/
if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI)) {
bp->b_flags &= ~B_DELWRI;
--numdirtybuffers;
numdirtywakeup(lodirtybuffers);
}
I believe that the correct fix is to change this code to:
/*
* If B_INVAL, clear B_DELWRI. We've already placed the buffer
* on the correct queue.
*/
if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI))
bundirty(bp);
I would appreciate it if everyone who is able to easily reproduce this
panic would test this fix and post your results back to the list. If
this solves the problem I will commit it to -current and -stable.
-Matt
Matthew Dillon
<dillon@backplane.com>
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