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[src/trunk]: src/sys Locking a layer vnode is racy as it may become reclaimed...
details: https://anonhg.NetBSD.org/src/rev/9339c2ce15a1
branches: trunk
changeset: 822653:9339c2ce15a1
user: hannken <hannken%NetBSD.org@localhost>
date: Thu Mar 30 09:16:52 2017 +0000
description:
Locking a layer vnode is racy as it may become reclaimed before
calling the operation on the lower vnode.
Replace vi_lock with a rw_obj and change layered file systems
to share the lock with the lower vnode.
Layered file systems now use genfs_lock()/_unlock/_islocked().
Welcome to 7.99.67
diffstat:
sys/kern/vfs_vnode.c | 23 +++++++++++++++---
sys/miscfs/genfs/genfs_vnops.c | 32 +++++++++++++-------------
sys/miscfs/genfs/layer_extern.h | 6 +++-
sys/miscfs/genfs/layer_vfsops.c | 7 ++++-
sys/miscfs/genfs/layer_vnops.c | 46 +------------------------------------
sys/miscfs/nullfs/null_vnops.c | 6 +++-
sys/miscfs/overlay/overlay_vnops.c | 8 ++++--
sys/miscfs/umapfs/umap_vnops.c | 6 +++-
sys/sys/param.h | 4 +-
sys/sys/vnode.h | 3 +-
sys/sys/vnode_impl.h | 4 +-
11 files changed, 65 insertions(+), 80 deletions(-)
diffs (truncated from 442 to 300 lines):
diff -r 46e3b058b1c4 -r 9339c2ce15a1 sys/kern/vfs_vnode.c
--- a/sys/kern/vfs_vnode.c Thu Mar 30 09:15:51 2017 +0000
+++ b/sys/kern/vfs_vnode.c Thu Mar 30 09:16:52 2017 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: vfs_vnode.c,v 1.80 2017/03/30 09:15:51 hannken Exp $ */
+/* $NetBSD: vfs_vnode.c,v 1.81 2017/03/30 09:16:52 hannken Exp $ */
/*-
* Copyright (c) 1997-2011 The NetBSD Foundation, Inc.
@@ -156,7 +156,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,v 1.80 2017/03/30 09:15:51 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,v 1.81 2017/03/30 09:16:52 hannken Exp $");
#include <sys/param.h>
#include <sys/kernel.h>
@@ -416,6 +416,21 @@
}
/*
+ * Set vnode to share another vnodes lock.
+ */
+void
+vshare_lock(vnode_t *vp, vnode_t *src_vp)
+{
+ vnode_impl_t *vip = VNODE_TO_VIMPL(vp);
+ vnode_impl_t *src_vip = VNODE_TO_VIMPL(src_vp);
+ krwlock_t *oldlock = vip->vi_lock;
+
+ rw_obj_hold(src_vip->vi_lock);
+ vip->vi_lock = src_vip->vi_lock;
+ rw_obj_free(oldlock);
+}
+
+/*
* Return the lru list this node should be on.
*/
static vnodelst_t *
@@ -1066,7 +1081,7 @@
vip = pool_cache_get(vcache_pool, PR_WAITOK);
memset(vip, 0, sizeof(*vip));
- rw_init(&vip->vi_lock);
+ vip->vi_lock = rw_obj_alloc();
/* SLIST_INIT(&vip->vi_hash); */
/* LIST_INIT(&vip->vi_nclist); */
/* LIST_INIT(&vip->vi_dnclist); */
@@ -1128,7 +1143,7 @@
if (vp->v_type == VBLK || vp->v_type == VCHR)
spec_node_destroy(vp);
- rw_destroy(&vip->vi_lock);
+ rw_obj_free(vip->vi_lock);
uvm_obj_destroy(&vp->v_uobj, true);
cv_destroy(&vp->v_cv);
pool_cache_put(vcache_pool, vip);
diff -r 46e3b058b1c4 -r 9339c2ce15a1 sys/miscfs/genfs/genfs_vnops.c
--- a/sys/miscfs/genfs/genfs_vnops.c Thu Mar 30 09:15:51 2017 +0000
+++ b/sys/miscfs/genfs/genfs_vnops.c Thu Mar 30 09:16:52 2017 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: genfs_vnops.c,v 1.193 2017/01/11 09:08:59 hannken Exp $ */
+/* $NetBSD: genfs_vnops.c,v 1.194 2017/03/30 09:16:52 hannken Exp $ */
/*-
* Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -57,7 +57,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: genfs_vnops.c,v 1.193 2017/01/11 09:08:59 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: genfs_vnops.c,v 1.194 2017/03/30 09:16:52 hannken Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@@ -295,7 +295,7 @@
op = (ISSET(flags, LK_EXCLUSIVE) ? RW_WRITER : RW_READER);
if (ISSET(flags, LK_NOWAIT)) {
- if (! rw_tryenter(&vip->vi_lock, op))
+ if (! rw_tryenter(vip->vi_lock, op))
return EBUSY;
if (mutex_tryenter(vp->v_interlock)) {
error = vdead_check(vp, VDEAD_NOWAIT);
@@ -305,25 +305,25 @@
} else
error = EBUSY;
if (error)
- rw_exit(&vip->vi_lock);
+ rw_exit(vip->vi_lock);
return error;
}
- rw_enter(&vip->vi_lock, op);
+ rw_enter(vip->vi_lock, op);
mutex_enter(vp->v_interlock);
error = vdead_check(vp, VDEAD_NOWAIT);
if (error == EBUSY) {
- rw_exit(&vip->vi_lock);
+ rw_exit(vip->vi_lock);
error = vdead_check(vp, 0);
KASSERT(error == ENOENT);
mutex_exit(vp->v_interlock);
- rw_enter(&vip->vi_lock, op);
+ rw_enter(vip->vi_lock, op);
mutex_enter(vp->v_interlock);
}
KASSERT(error == ENOENT);
mutex_exit(vp->v_interlock);
if (! ISSET(flags, LK_RETRY)) {
- rw_exit(&vip->vi_lock);
+ rw_exit(vip->vi_lock);
return ENOENT;
}
return 0;
@@ -341,7 +341,7 @@
vnode_t *vp = ap->a_vp;
vnode_impl_t *vip = VNODE_TO_VIMPL(vp);
- rw_exit(&vip->vi_lock);
+ rw_exit(vip->vi_lock);
return 0;
}
@@ -367,7 +367,7 @@
if (ISSET(flags, LK_NOWAIT)) {
if (fstrans_start_nowait(mp, FSTRANS_SHARED))
return EBUSY;
- if (! rw_tryenter(&vip->vi_lock, op)) {
+ if (! rw_tryenter(vip->vi_lock, op)) {
fstrans_done(mp);
return EBUSY;
}
@@ -377,18 +377,18 @@
} else
error = EBUSY;
if (error) {
- rw_exit(&vip->vi_lock);
+ rw_exit(vip->vi_lock);
fstrans_done(mp);
}
return error;
}
fstrans_start(mp, FSTRANS_SHARED);
- rw_enter(&vip->vi_lock, op);
+ rw_enter(vip->vi_lock, op);
mutex_enter(vp->v_interlock);
error = vdead_check(vp, VDEAD_NOWAIT);
if (error) {
- rw_exit(&vip->vi_lock);
+ rw_exit(vip->vi_lock);
fstrans_done(mp);
error = vdead_check(vp, 0);
KASSERT(error == ENOENT);
@@ -410,7 +410,7 @@
vnode_impl_t *vip = VNODE_TO_VIMPL(vp);
struct mount *mp = vp->v_mount;
- rw_exit(&vip->vi_lock);
+ rw_exit(vip->vi_lock);
fstrans_done(mp);
return 0;
@@ -428,10 +428,10 @@
vnode_t *vp = ap->a_vp;
vnode_impl_t *vip = VNODE_TO_VIMPL(vp);
- if (rw_write_held(&vip->vi_lock))
+ if (rw_write_held(vip->vi_lock))
return LK_EXCLUSIVE;
- if (rw_read_held(&vip->vi_lock))
+ if (rw_read_held(vip->vi_lock))
return LK_SHARED;
return 0;
diff -r 46e3b058b1c4 -r 9339c2ce15a1 sys/miscfs/genfs/layer_extern.h
--- a/sys/miscfs/genfs/layer_extern.h Thu Mar 30 09:15:51 2017 +0000
+++ b/sys/miscfs/genfs/layer_extern.h Thu Mar 30 09:16:52 2017 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: layer_extern.h,v 1.38 2017/02/17 08:31:25 hannken Exp $ */
+/* $NetBSD: layer_extern.h,v 1.39 2017/03/30 09:16:52 hannken Exp $ */
/*
* Copyright (c) 1999 National Aeronautics & Space Administration
@@ -99,7 +99,6 @@
int layer_getattr(void *);
int layer_inactive(void *);
int layer_reclaim(void *);
-int layer_lock(void *);
int layer_print(void *);
int layer_bmap(void *);
int layer_fsync(void *);
@@ -114,5 +113,8 @@
int layer_rmdir(void *);
int layer_getpages(void *);
int layer_putpages(void *);
+#define layer_lock genfs_lock
+#define layer_unlock genfs_unlock
+#define layer_islocked genfs_islocked
#endif /* _MISCFS_GENFS_LAYER_EXTERN_H_ */
diff -r 46e3b058b1c4 -r 9339c2ce15a1 sys/miscfs/genfs/layer_vfsops.c
--- a/sys/miscfs/genfs/layer_vfsops.c Thu Mar 30 09:15:51 2017 +0000
+++ b/sys/miscfs/genfs/layer_vfsops.c Thu Mar 30 09:16:52 2017 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: layer_vfsops.c,v 1.47 2017/02/17 08:31:25 hannken Exp $ */
+/* $NetBSD: layer_vfsops.c,v 1.48 2017/03/30 09:16:52 hannken Exp $ */
/*
* Copyright (c) 1999 National Aeronautics & Space Administration
@@ -74,7 +74,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: layer_vfsops.c,v 1.47 2017/02/17 08:31:25 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: layer_vfsops.c,v 1.48 2017/03/30 09:16:52 hannken Exp $");
#include <sys/param.h>
#include <sys/sysctl.h>
@@ -223,6 +223,9 @@
mutex_obj_hold(lowervp->v_interlock);
uvm_obj_setlock(&vp->v_uobj, lowervp->v_interlock);
+ /* Share the lock with the lower node. */
+ vshare_lock(vp, lowervp);
+
vp->v_tag = lmp->layerm_tag;
vp->v_type = lowervp->v_type;
vp->v_op = lmp->layerm_vnodeop_p;
diff -r 46e3b058b1c4 -r 9339c2ce15a1 sys/miscfs/genfs/layer_vnops.c
--- a/sys/miscfs/genfs/layer_vnops.c Thu Mar 30 09:15:51 2017 +0000
+++ b/sys/miscfs/genfs/layer_vnops.c Thu Mar 30 09:16:52 2017 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: layer_vnops.c,v 1.60 2017/01/27 10:47:13 hannken Exp $ */
+/* $NetBSD: layer_vnops.c,v 1.61 2017/03/30 09:16:52 hannken Exp $ */
/*
* Copyright (c) 1999 National Aeronautics & Space Administration
@@ -170,7 +170,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: layer_vnops.c,v 1.60 2017/01/27 10:47:13 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: layer_vnops.c,v 1.61 2017/03/30 09:16:52 hannken Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@@ -743,48 +743,6 @@
return 0;
}
-int
-layer_lock(void *v)
-{
- struct vop_lock_args /* {
- struct vnode *a_vp;
- int a_flags;
- } */ *ap = v;
- struct vnode *vp = ap->a_vp;
- struct vnode *lowervp = LAYERVPTOLOWERVP(vp);
- int flags = ap->a_flags;
- int error;
-
- if (ISSET(flags, LK_NOWAIT)) {
- error = VOP_LOCK(lowervp, flags);
- if (error)
- return error;
- if (mutex_tryenter(vp->v_interlock)) {
- error = vdead_check(vp, VDEAD_NOWAIT);
- mutex_exit(vp->v_interlock);
- } else
- error = EBUSY;
- if (error)
- VOP_UNLOCK(lowervp);
- return error;
- }
-
- error = VOP_LOCK(lowervp, flags);
- if (error)
- return error;
-
- mutex_enter(vp->v_interlock);
- error = vdead_check(vp, VDEAD_NOWAIT);
- if (error) {
- VOP_UNLOCK(lowervp);
- error = vdead_check(vp, 0);
- KASSERT(error == ENOENT);
- }
- mutex_exit(vp->v_interlock);
-
- return error;
-}
-
/*
* We just feed the returned vnode up to the caller - there's no need
* to build a layer node on top of the node on which we're going to do
diff -r 46e3b058b1c4 -r 9339c2ce15a1 sys/miscfs/nullfs/null_vnops.c
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