Module Name: src
Committed By: hannken
Date: Fri Jul 16 08:23:28 UTC 2010
Modified Files:
src/sys/fs/union: union_subr.c
Log Message:
Always take the hash list lock before removing a node from the hash chain.
Release the hash list lock before calling getnewvnode() and check the
hash list again like other file systems do.
Take v_interlock before calling vget().
To generate a diff of this commit:
cvs rdiff -u -r1.37 -r1.38 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:1.37 src/sys/fs/union/union_subr.c:1.38
--- src/sys/fs/union/union_subr.c:1.37 Thu Jun 24 13:03:11 2010
+++ src/sys/fs/union/union_subr.c Fri Jul 16 08:23:28 2010
@@ -1,4 +1,4 @@
-/* $NetBSD: union_subr.c,v 1.37 2010/06/24 13:03:11 hannken Exp $ */
+/* $NetBSD: union_subr.c,v 1.38 2010/07/16 08:23:28 hannken Exp $ */
/*
* Copyright (c) 1994
@@ -72,7 +72,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: union_subr.c,v 1.37 2010/06/24 13:03:11 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: union_subr.c,v 1.38 2010/07/16 08:23:28 hannken Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@@ -330,8 +330,8 @@
{
int error;
struct vattr va;
- struct union_node *un = NULL;
- struct vnode *xlowervp = NULLVP;
+ struct union_node *un = NULL, *un1;
+ struct vnode *vp, *xlowervp = NULLVP;
struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
voff_t uppersz, lowersz;
int hash = 0;
@@ -394,7 +394,9 @@
(un->un_uppervp == uppervp ||
un->un_uppervp == NULLVP) &&
(UNIONTOV(un)->v_mount == mp)) {
- if (vget(UNIONTOV(un), 0)) {
+ vp = UNIONTOV(un);
+ mutex_enter(&vp->v_interlock);
+ if (vget(vp, LK_INTERLOCK)) {
union_list_unlock(hash);
goto loop;
}
@@ -502,17 +504,7 @@
if (lowervp != NULLVP)
if (VOP_GETATTR(lowervp, &va, FSCRED) == 0)
lowersz = va.va_size;
-
- if (docache) {
- /*
- * otherwise lock the vp list while we call getnewvnode
- * since that can block.
- */
- hash = UNION_HASH(uppervp, lowervp);
-
- if (union_list_lock(hash))
- goto loop;
- }
+ hash = UNION_HASH(uppervp, lowervp);
error = getnewvnode(VT_UNION, mp, union_vnodeop_p, vpp);
if (error) {
@@ -528,6 +520,24 @@
goto out;
}
+ if (docache) {
+ while (union_list_lock(hash))
+ continue;
+ LIST_FOREACH(un1, &unhead[hash], un_cache) {
+ if (un1->un_lowervp == lowervp &&
+ un1->un_uppervp == uppervp &&
+ UNIONTOV(un1)->v_mount == mp) {
+ /*
+ * Another thread beat us, push back freshly
+ * allocated vnode and retry.
+ */
+ union_list_unlock(hash);
+ ungetnewvnode(*vpp);
+ goto loop;
+ }
+ }
+ }
+
(*vpp)->v_data = malloc(sizeof(struct union_node), M_TEMP, M_WAITOK);
(*vpp)->v_vflag |= vflag;
@@ -590,12 +600,18 @@
int
union_freevp(struct vnode *vp)
{
+ int hash;
struct union_node *un = VTOUNION(vp);
+ hash = UNION_HASH(un->un_uppervp, un->un_lowervp);
+
+ while (union_list_lock(hash))
+ continue;
if (un->un_flags & UN_CACHED) {
un->un_flags &= ~UN_CACHED;
LIST_REMOVE(un, un_cache);
}
+ union_list_unlock(hash);
if (un->un_pvp != NULLVP)
vrele(un->un_pvp);
@@ -998,6 +1014,8 @@
void
union_removed_upper(struct union_node *un)
{
+ int hash;
+
#if 1
/*
* We do not set the uppervp to NULLVP here, because lowervp
@@ -1013,10 +1031,15 @@
union_newupper(un, NULLVP);
#endif
+ hash = UNION_HASH(un->un_uppervp, un->un_lowervp);
+
+ while (union_list_lock(hash))
+ continue;
if (un->un_flags & UN_CACHED) {
un->un_flags &= ~UN_CACHED;
LIST_REMOVE(un, un_cache);
}
+ union_list_unlock(hash);
if (un->un_flags & UN_ULOCK) {
un->un_flags &= ~UN_ULOCK;
