Module Name: src
Committed By: hannken
Date: Fri Nov 25 11:19:10 UTC 2011
Modified Files:
src/sys/fs/union: union_subr.c
Log Message:
When union_allocvp() finds a node being cleaned out and the caller holds
a lock, ignore the node and continue. To allow the cleaning to succeed
the current threadmust make progress.
For a brief time the cache may contain more than one vnode referring to
a lower node.
Don't unlock the hash mutex if getnewvnode fails -- we don't hold it.
To generate a diff of this commit:
cvs rdiff -u -r1.54 -r1.55 src/sys/fs/union/union_subr.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/fs/union/union_subr.c
diff -u src/sys/fs/union/union_subr.c:1.54 src/sys/fs/union/union_subr.c:1.55
--- src/sys/fs/union/union_subr.c:1.54 Wed Nov 23 19:39:11 2011
+++ src/sys/fs/union/union_subr.c Fri Nov 25 11:19:10 2011
@@ -1,4 +1,4 @@
-/* $NetBSD: union_subr.c,v 1.54 2011/11/23 19:39:11 hannken Exp $ */
+/* $NetBSD: union_subr.c,v 1.55 2011/11/25 11:19:10 hannken Exp $ */
/*
* Copyright (c) 1994
@@ -72,7 +72,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: union_subr.c,v 1.54 2011/11/23 19:39:11 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: union_subr.c,v 1.55 2011/11/25 11:19:10 hannken Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@@ -404,6 +404,18 @@ loop:
lflag = LK_EXCLUSIVE;
vp = UNIONTOV(un);
mutex_enter(vp->v_interlock);
+ /*
+ * If this node being cleaned out and our caller
+ * holds a lock, then ignore it and continue. To
+ * allow the cleaning to succeed the current thread
+ * must make progress. For a brief time the cache
+ * may contain more than one vnode referring to
+ * a lower node.
+ */
+ if ((vp->v_iflag & VI_XLOCK) != 0 && lflag == 0) {
+ mutex_exit(vp->v_interlock);
+ continue;
+ }
mutex_exit(&uhash_lock);
if (vget(vp, lflag))
goto loop;
@@ -484,7 +496,7 @@ found:
if (lowervp)
vrele(lowervp);
- goto out;
+ return error;
}
if (docache) {
@@ -493,6 +505,17 @@ found:
if (un1->un_lowervp == lowervp &&
un1->un_uppervp == uppervp &&
UNIONTOV(un1)->v_mount == mp) {
+ vp = UNIONTOV(un1);
+ mutex_enter(vp->v_interlock);
+ /*
+ * Ignore nodes being cleaned out.
+ * See the cache lookup above.
+ */
+ if ((vp->v_iflag & VI_XLOCK) != 0) {
+ mutex_exit(vp->v_interlock);
+ continue;
+ }
+ mutex_exit(vp->v_interlock);
/*
* Another thread beat us, push back freshly
* allocated vnode and retry.
@@ -569,7 +592,6 @@ found:
if (xlowervp)
vrele(xlowervp);
-out:
if (docache)
mutex_exit(&uhash_lock);
