A bug in specfs's fsync dating back to Kirk's original softupdates work
( which required a similar mark/scan fix to the FFS fsync ) appears to
have been exposed by recent pageout peformance commits I made.
I've committed a mark/scan fix to specfs's fsync, which appears
to solve the lockups Poul was getting doing a 'cvs update -PdA' under
-current. It should solve the problem for the other two people who
reported the same lockup.
I'm not sure why -stable isn't affected. The bug is in -stable as well.
I'll MFC it in two days unless I see complaints sooner. It's a simple
bug fix.
At some point I need to go through all the fsync implementations...
they need the same sort of placemarker fix that I threw into the
pageout daemon scan. The current code uses the 'goto loop' hack, which
is terribly inefficient when combined with a heavily loaded
softupdates-enabled system.
-Matt
Index: spec_vnops.c
===================================================================
RCS file: /home/ncvs/src/sys/miscfs/specfs/spec_vnops.c,v
retrieving revision 1.147
retrieving revision 1.148
diff -u -r1.147 -r1.148
--- spec_vnops.c 2000/12/26 19:41:37 1.147
+++ spec_vnops.c 2000/12/30 23:32:24 1.148
@@ -31,7 +31,7 @@
* SUCH DAMAGE.
*
* @(#)spec_vnops.c 8.14 (Berkeley) 5/21/95
- * $FreeBSD: src/sys/miscfs/specfs/spec_vnops.c,v 1.147 2000/12/26 19:41:37 dillon
Exp $
+ * $FreeBSD: src/sys/miscfs/specfs/spec_vnops.c,v 1.148 2000/12/30 23:32:24 dillon
+Exp $
*/
#include <sys/param.h>
@@ -352,12 +352,25 @@
return (0);
/*
+ * MARK/SCAN initialization to avoid infinite loops
+ */
+ s = splbio();
+ for (bp = TAILQ_FIRST(&vp->v_dirtyblkhd); bp;
+ bp = TAILQ_NEXT(bp, b_vnbufs)) {
+ bp->b_flags &= ~B_SCANNED;
+ }
+ splx(s);
+
+ /*
* Flush all dirty buffers associated with a block device.
*/
loop:
s = splbio();
for (bp = TAILQ_FIRST(&vp->v_dirtyblkhd); bp; bp = nbp) {
nbp = TAILQ_NEXT(bp, b_vnbufs);
+ if ((bp->b_flags & B_SCANNED) != 0)
+ continue;
+ bp->b_flags |= B_SCANNED;
if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT))
continue;
if ((bp->b_flags & B_DELWRI) == 0)
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