Date: Tue, 29 Jun 1999 00:57:38 +0800 From: Peter Wemm <peter@netplex.com.au> To: Kirk McKusick <mckusick@flamingo.McKusick.COM> Cc: Julian Elischer <julian@whistle.com>, Matthew Dillon <dillon@apollo.backplane.com>, Alan Cox <alc@cs.rice.edu>, Mike Smith <mike@smith.net.au>, "John S. Dyson" <toor@dyson.iquest.net>, dg@root.com, dyson@iquest.net, current@freebsd.org, Greg Lehey <grog@lemis.com> Subject: Re: Found the startup panic - ccd ( patch included ) Message-ID: <19990628165738.E590283@overcee.netplex.com.au> In-Reply-To: Your message of "Mon, 28 Jun 1999 04:54:07 MST." <199906281154.EAA02335@flamingo.McKusick.COM>
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Kirk McKusick wrote:
[..]
I've been tinkering around for a while and think I have at least a
partial fix for the remaining problems.
Certain places use B_CALL and have biodone() from the b_iodone routine,
so we can't reliably use B_ASYNC as an indicator of needing to reassign
to LK_KERNPROC. We have to do it on a case-by-case basis.
It's easier to do cluster_head processing at the point it's gathered
rather than in BUF_KERNPROC().
vfs_cluster.c is confusing, but I think I've figured out how to get it
right. I'm not 100% sure about checking for B_CALL in both cases prior
to VOP_STRATEGY(), and maybe reqbp needs to be considered for the first
read in cluster_read().
Also, I think the inline BUF_*() routines/macros would be better as
routines in something like vfs_bio.c as the internals cause problems
with prototypes etc.
I think this patch fixes the remaining panics in pageouts and clustering.
Index: kern/vfs_bio.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/vfs_bio.c,v
retrieving revision 1.218
diff -u -r1.218 vfs_bio.c
--- vfs_bio.c 1999/06/28 15:32:10 1.218
+++ vfs_bio.c 1999/06/28 16:48:53
@@ -517,7 +517,8 @@
if (curproc != NULL)
curproc->p_stats->p_ru.ru_oublock++;
splx(s);
- BUF_KERNPROC(bp);
+ if (oldflags & B_ASYNC)
+ BUF_KERNPROC(bp);
VOP_STRATEGY(bp->b_vp, bp);
/*
Index: kern/vfs_cluster.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/vfs_cluster.c,v
retrieving revision 1.84
diff -u -r1.84 vfs_cluster.c
--- vfs_cluster.c 1999/06/26 02:46:08 1.84
+++ vfs_cluster.c 1999/06/28 16:48:53
@@ -252,7 +252,8 @@
if ((bp->b_flags & B_CLUSTER) == 0)
vfs_busy_pages(bp, 0);
bp->b_flags &= ~(B_ERROR|B_INVAL);
- BUF_KERNPROC(bp);
+ if (bp->b_flags & (B_ASYNC|B_CALL))
+ BUF_KERNPROC(bp);
error = VOP_STRATEGY(vp, bp);
curproc->p_stats->p_ru.ru_inblock++;
}
@@ -286,7 +287,8 @@
if ((rbp->b_flags & B_CLUSTER) == 0)
vfs_busy_pages(rbp, 0);
rbp->b_flags &= ~(B_ERROR|B_INVAL);
- BUF_KERNPROC(rbp);
+ if (rbp->b_flags & (B_ASYNC|B_CALL))
+ BUF_KERNPROC(rbp);
(void) VOP_STRATEGY(vp, rbp);
curproc->p_stats->p_ru.ru_inblock++;
}
@@ -414,6 +416,11 @@
break;
}
}
+ /*
+ * XXX fbp from caller may not be B_ASYNC, but we are going
+ * to biodone() it in cluster_callback() anyway
+ */
+ BUF_KERNPROC(tbp);
TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
tbp, b_cluster.cluster_entry);
for (j = 0; j < tbp->b_npages; j += 1) {
@@ -788,6 +795,7 @@
reassignbuf(tbp, tbp->b_vp); /* put on clean list */
++tbp->b_vp->v_numoutput;
splx(s);
+ BUF_KERNPROC(tbp);
TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
tbp, b_cluster.cluster_entry);
}
Index: sys/buf.h
===================================================================
RCS file: /home/ncvs/src/sys/sys/buf.h,v
retrieving revision 1.73
diff -u -r1.73 buf.h
--- buf.h 1999/06/27 11:40:03 1.73
+++ buf.h 1999/06/28 16:48:53
@@ -315,17 +315,8 @@
static __inline void
BUF_KERNPROC(struct buf *bp)
{
- struct buf *nbp;
- int s;
- s = splbio();
- if (bp->b_flags & B_ASYNC)
- bp->b_lock.lk_lockholder = LK_KERNPROC;
- for (nbp = TAILQ_FIRST(&bp->b_cluster.cluster_head);
- nbp; nbp = TAILQ_NEXT(&nbp->b_cluster, cluster_entry))
- if (nbp->b_flags & B_ASYNC)
- nbp->b_lock.lk_lockholder = LK_KERNPROC;
- splx(s);
+ bp->b_lock.lk_lockholder = LK_KERNPROC;
}
/*
* Find out the number of references to a lock.
Cheers,
-Peter
--
Peter Wemm - peter@FreeBSD.org; peter@yahoo-inc.com; peter@netplex.com.au
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