Module Name: src
Committed By: hannken
Date: Sun Nov 3 08:33:00 UTC 2013
Modified Files:
src/sys/kern: vfs_vnode.c
Log Message:
cleanvnode():
- VC_XLOCK/VC_MASK are not used anymore, remove.
- If we get a reference while cleaning, there is no need to retry as
these reference and this vnode will disappear soon.
- Make sure we run inside a fstrans transaction to prevent deadlocks
against vget().
vrecycle():
- don't even try to recycle a vnode currently cleaning.
To generate a diff of this commit:
cvs rdiff -u -r1.23 -r1.24 src/sys/kern/vfs_vnode.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/kern/vfs_vnode.c
diff -u src/sys/kern/vfs_vnode.c:1.23 src/sys/kern/vfs_vnode.c:1.24
--- src/sys/kern/vfs_vnode.c:1.23 Tue Oct 29 09:53:51 2013
+++ src/sys/kern/vfs_vnode.c Sun Nov 3 08:33:00 2013
@@ -1,4 +1,4 @@
-/* $NetBSD: vfs_vnode.c,v 1.23 2013/10/29 09:53:51 hannken Exp $ */
+/* $NetBSD: vfs_vnode.c,v 1.24 2013/11/03 08:33:00 hannken Exp $ */
/*-
* Copyright (c) 1997-2011 The NetBSD Foundation, Inc.
@@ -106,18 +106,8 @@
* from zero, the interlock must be held. To change from a non-zero
* value to zero, again the interlock must be held.
*
- * There is a flag bit, VC_XLOCK, embedded in v_usecount. To raise
- * v_usecount, if the VC_XLOCK bit is set in it, the interlock must
- * be held. To modify the VC_XLOCK bit, the interlock must be held.
- * We always keep the usecount (v_usecount & VC_MASK) non-zero while
- * the VC_XLOCK bit is set.
- *
- * Unless the VC_XLOCK bit is set, changing the usecount from a non-zero
- * value to a non-zero value can safely be done using atomic operations,
- * without the interlock held.
- *
- * Even if the VC_XLOCK bit is set, decreasing the usecount to a non-zero
- * value can be done using atomic operations, without the interlock held.
+ * Changing the usecount from a non-zero value to a non-zero value can
+ * safely be done using atomic operations, without the interlock held.
*
* Note: if VI_CLEAN is set, vnode_t::v_interlock will be released while
* mntvnode_lock is still held.
@@ -126,7 +116,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,v 1.23 2013/10/29 09:53:51 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,v 1.24 2013/11/03 08:33:00 hannken Exp $");
#define _VFS_VNODE_PRIVATE
@@ -148,14 +138,11 @@ __KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,
#include <sys/systm.h>
#include <sys/vnode.h>
#include <sys/wapbl.h>
+#include <sys/fstrans.h>
#include <uvm/uvm.h>
#include <uvm/uvm_readahead.h>
-/* v_usecount; see the comment near the top of vfs_vnode.c */
-#define VC_XLOCK 0x80000000
-#define VC_MASK 0x7fffffff
-
#define DOCLOSE 0x0008 /* vclean: close active files */
/* Flags to vrelel. */
@@ -284,9 +271,10 @@ cleanvnode(void)
{
vnode_t *vp;
vnodelst_t *listhd;
+ struct mount *mp;
KASSERT(mutex_owned(&vnode_free_list_lock));
-retry:
+
listhd = &vnode_free_list;
try_nextlist:
TAILQ_FOREACH(vp, listhd, v_freelist) {
@@ -302,9 +290,16 @@ try_nextlist:
if (!mutex_tryenter(vp->v_interlock))
continue;
- if ((vp->v_iflag & VI_XLOCK) == 0)
- break;
- mutex_exit(vp->v_interlock);
+ if ((vp->v_iflag & VI_XLOCK) != 0) {
+ mutex_exit(vp->v_interlock);
+ continue;
+ }
+ mp = vp->v_mount;
+ if (fstrans_start_nowait(mp, FSTRANS_SHARED) != 0) {
+ mutex_exit(vp->v_interlock);
+ continue;
+ }
+ break;
}
if (vp == NULL) {
@@ -326,37 +321,12 @@ try_nextlist:
/*
* The vnode is still associated with a file system, so we must
* clean it out before freeing it. We need to add a reference
- * before doing this. If the vnode gains another reference while
- * being cleaned out then we lose - retry.
+ * before doing this.
*/
- atomic_add_int(&vp->v_usecount, 1 + VC_XLOCK);
+ vp->v_usecount = 1;
vclean(vp, DOCLOSE);
- KASSERT(vp->v_usecount >= 1 + VC_XLOCK);
- atomic_add_int(&vp->v_usecount, -VC_XLOCK);
- if (vp->v_usecount > 1) {
- /*
- * Don't return to freelist - the holder of the last
- * reference will destroy it.
- */
- vrelel(vp, 0); /* releases vp->v_interlock */
- mutex_enter(&vnode_free_list_lock);
- goto retry;
- }
-
- KASSERT((vp->v_iflag & VI_CLEAN) == VI_CLEAN);
- mutex_exit(vp->v_interlock);
- if (vp->v_type == VBLK || vp->v_type == VCHR) {
- spec_node_destroy(vp);
- }
- vp->v_type = VNON;
-
- KASSERT(vp->v_data == NULL);
- KASSERT(vp->v_uobj.uo_npages == 0);
- KASSERT(TAILQ_EMPTY(&vp->v_uobj.memq));
- KASSERT(vp->v_numoutput == 0);
- KASSERT((vp->v_iflag & VI_ONWORKLST) == 0);
-
- vrele(vp);
+ vrelel(vp, 0);
+ fstrans_done(mp);
return 0;
}
@@ -604,7 +574,7 @@ vtryrele(vnode_t *vp)
if (use == 1) {
return false;
}
- KASSERT((use & VC_MASK) > 1);
+ KASSERT(use > 1);
next = atomic_cas_uint(&vp->v_usecount, use, use - 1);
if (__predict_true(next == use)) {
return true;
@@ -990,7 +960,7 @@ vclean(vnode_t *vp, int flags)
atomic_add_int(&uvmexp.filepages, vp->v_uobj.uo_npages);
}
vp->v_iflag &= ~(VI_TEXT|VI_EXECMAP);
- active = (vp->v_usecount & VC_MASK) > 1;
+ active = (vp->v_usecount > 1);
/* XXXAD should not lock vnode under layer */
mutex_exit(vp->v_interlock);
@@ -1085,7 +1055,7 @@ vrecycle(vnode_t *vp, kmutex_t *inter_lk
KASSERT((vp->v_iflag & VI_MARKER) == 0);
mutex_enter(vp->v_interlock);
- if (vp->v_usecount != 0) {
+ if (vp->v_usecount != 0 || (vp->v_iflag & (VI_CLEAN|VI_XLOCK)) != 0) {
mutex_exit(vp->v_interlock);
return 0;
}
