Module Name: src
Committed By: hannken
Date: Thu Mar 30 09:14:59 UTC 2017
Modified Files:
src/sys/kern: vfs_vnode.c
Log Message:
Change vrelel() to defer the test for a reclaimed vnode until
we hold both the interlock and the vnode lock.
Add a common operation to deallocate a vnode in state LOADING.
To generate a diff of this commit:
cvs rdiff -u -r1.78 -r1.79 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:1.78 src/sys/kern/vfs_vnode.c:1.79
--- src/sys/kern/vfs_vnode.c:1.78 Thu Mar 30 09:14:08 2017
+++ src/sys/kern/vfs_vnode.c Thu Mar 30 09:14:59 2017
@@ -1,4 +1,4 @@
-/* $NetBSD: vfs_vnode.c,v 1.78 2017/03/30 09:14:08 hannken Exp $ */
+/* $NetBSD: vfs_vnode.c,v 1.79 2017/03/30 09:14:59 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 1.78 2017/03/30 09:14:08 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,v 1.79 2017/03/30 09:14:59 hannken Exp $");
#include <sys/param.h>
#include <sys/kernel.h>
@@ -212,6 +212,7 @@ static pool_cache_t vcache_pool;
static void lru_requeue(vnode_t *, vnodelst_t *);
static vnodelst_t * lru_which(vnode_t *);
static vnode_impl_t * vcache_alloc(void);
+static void vcache_dealloc(vnode_impl_t *);
static void vcache_free(vnode_impl_t *);
static void vcache_init(void);
static void vcache_reinit(void);
@@ -662,6 +663,8 @@ vtryrele(vnode_t *vp)
static void
vrelel(vnode_t *vp, int flags)
{
+ const bool async = ((flags & VRELEL_ASYNC_RELE) != 0);
+ const bool force = ((flags & VRELEL_FORCE_RELE) != 0);
bool recycle, defer;
int error;
@@ -692,62 +695,48 @@ vrelel(vnode_t *vp, int flags)
#endif
/*
- * If not clean, deactivate the vnode, but preserve
- * our reference across the call to VOP_INACTIVE().
+ * First try to get the vnode locked for VOP_INACTIVE().
+ * Defer vnode release to vdrain_thread if caller requests
+ * it explicitly, is the pagedaemon or the lock failed.
*/
- if (VSTATE_GET(vp) != VS_RECLAIMED) {
- recycle = false;
-
+ if ((curlwp == uvm.pagedaemon_lwp) || async) {
+ defer = true;
+ } else {
+ mutex_exit(vp->v_interlock);
+ error = vn_lock(vp,
+ LK_EXCLUSIVE | LK_RETRY | (force ? 0 : LK_NOWAIT));
+ defer = (error != 0);
+ mutex_enter(vp->v_interlock);
+ }
+ KASSERT(mutex_owned(vp->v_interlock));
+ KASSERT(! (force && defer));
+ if (defer) {
/*
- * XXX This ugly block can be largely eliminated if
- * locking is pushed down into the file systems.
- *
- * Defer vnode release to vdrain_thread if caller
- * requests it explicitly or is the pagedaemon.
+ * Defer reclaim to the kthread; it's not safe to
+ * clean it here. We donate it our last reference.
*/
- if ((curlwp == uvm.pagedaemon_lwp) ||
- (flags & VRELEL_ASYNC_RELE) != 0) {
- defer = true;
- } else if ((flags & VRELEL_FORCE_RELE) != 0) {
- /*
- * We have to try harder.
- */
- mutex_exit(vp->v_interlock);
- error = vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
- KASSERTMSG((error == 0), "vn_lock failed: %d", error);
- mutex_enter(vp->v_interlock);
- defer = false;
- } else {
- /* If we can't acquire the lock, then defer. */
- mutex_exit(vp->v_interlock);
- error = vn_lock(vp,
- LK_EXCLUSIVE | LK_RETRY | LK_NOWAIT);
- defer = (error != 0);
- mutex_enter(vp->v_interlock);
- }
-
- KASSERT(mutex_owned(vp->v_interlock));
- KASSERT(! ((flags & VRELEL_FORCE_RELE) != 0 && defer));
+ lru_requeue(vp, &lru_vrele_list);
+ mutex_exit(vp->v_interlock);
+ return;
+ }
- if (defer) {
- /*
- * Defer reclaim to the kthread; it's not safe to
- * clean it here. We donate it our last reference.
- */
- lru_requeue(vp, &lru_vrele_list);
- mutex_exit(vp->v_interlock);
- return;
- }
+ /*
+ * If the node got another reference while we
+ * released the interlock, don't try to inactivate it yet.
+ */
+ if (__predict_false(vtryrele(vp))) {
+ VOP_UNLOCK(vp);
+ mutex_exit(vp->v_interlock);
+ return;
+ }
- /*
- * If the node got another reference while we
- * released the interlock, don't try to inactivate it yet.
- */
- if (__predict_false(vtryrele(vp))) {
- VOP_UNLOCK(vp);
- mutex_exit(vp->v_interlock);
- return;
- }
+ /*
+ * If not clean, deactivate the vnode, but preserve
+ * our reference across the call to VOP_INACTIVE().
+ */
+ if (VSTATE_GET(vp) == VS_RECLAIMED) {
+ VOP_UNLOCK(vp);
+ } else {
VSTATE_CHANGE(vp, VS_ACTIVE, VS_BLOCKED);
mutex_exit(vp->v_interlock);
@@ -759,6 +748,7 @@ vrelel(vnode_t *vp, int flags)
*
* Note that VOP_INACTIVE() will drop the vnode lock.
*/
+ recycle = false;
VOP_INACTIVE(vp, &recycle);
if (recycle) {
/* vcache_reclaim() below will drop the lock. */
@@ -1097,6 +1087,26 @@ vcache_alloc(void)
}
/*
+ * Deallocate a vcache node in state VS_LOADING.
+ *
+ * vcache_lock held on entry and released on return.
+ */
+static void
+vcache_dealloc(vnode_impl_t *vip)
+{
+ vnode_t *vp;
+
+ KASSERT(mutex_owned(&vcache_lock));
+
+ vp = VIMPL_TO_VNODE(vip);
+ mutex_enter(vp->v_interlock);
+ vp->v_op = dead_vnodeop_p;
+ VSTATE_CHANGE(vp, VS_LOADING, VS_RECLAIMED);
+ mutex_exit(&vcache_lock);
+ vrelel(vp, 0);
+}
+
+/*
* Free an unused, unreferenced vcache node.
* v_interlock locked on entry.
*/
@@ -1260,10 +1270,7 @@ again:
/* If another thread beat us inserting this node, retry. */
if (vip != new_vip) {
- mutex_enter(vp->v_interlock);
- VSTATE_CHANGE(vp, VS_LOADING, VS_RECLAIMED);
- mutex_exit(&vcache_lock);
- vrelel(vp, 0);
+ vcache_dealloc(new_vip);
vfs_unbusy(mp, false, NULL);
goto again;
}
@@ -1275,10 +1282,7 @@ again:
mutex_enter(&vcache_lock);
SLIST_REMOVE(&vcache_hashtab[hash & vcache_hashmask],
new_vip, vnode_impl, vi_hash);
- mutex_enter(vp->v_interlock);
- VSTATE_CHANGE(vp, VS_LOADING, VS_RECLAIMED);
- mutex_exit(&vcache_lock);
- vrelel(vp, 0);
+ vcache_dealloc(new_vip);
vfs_unbusy(mp, false, NULL);
KASSERT(*vpp == NULL);
return error;
@@ -1329,10 +1333,7 @@ vcache_new(struct mount *mp, struct vnod
&vip->vi_key.vk_key_len, &vip->vi_key.vk_key);
if (error) {
mutex_enter(&vcache_lock);
- mutex_enter(vp->v_interlock);
- VSTATE_CHANGE(vp, VS_LOADING, VS_RECLAIMED);
- mutex_exit(&vcache_lock);
- vrelel(vp, 0);
+ vcache_dealloc(vip);
vfs_unbusy(mp, false, NULL);
KASSERT(*vpp == NULL);
return error;
@@ -1381,7 +1382,6 @@ vcache_rekey_enter(struct mount *mp, str
uint32_t old_hash, new_hash;
struct vcache_key old_vcache_key, new_vcache_key;
vnode_impl_t *vip, *new_vip;
- struct vnode *new_vp;
old_vcache_key.vk_mount = mp;
old_vcache_key.vk_key = old_key;
@@ -1395,16 +1395,12 @@ vcache_rekey_enter(struct mount *mp, str
new_vip = vcache_alloc();
new_vip->vi_key = new_vcache_key;
- new_vp = VIMPL_TO_VNODE(new_vip);
/* Insert locked new node used as placeholder. */
mutex_enter(&vcache_lock);
vip = vcache_hash_lookup(&new_vcache_key, new_hash);
if (vip != NULL) {
- mutex_enter(new_vp->v_interlock);
- VSTATE_CHANGE(new_vp, VS_LOADING, VS_RECLAIMED);
- mutex_exit(&vcache_lock);
- vrelel(new_vp, 0);
+ vcache_dealloc(new_vip);
return EEXIST;
}
SLIST_INSERT_HEAD(&vcache_hashtab[new_hash & vcache_hashmask],
@@ -1456,6 +1452,7 @@ vcache_rekey_exit(struct mount *mp, stru
new_vp = VIMPL_TO_VNODE(new_vip);
mutex_enter(new_vp->v_interlock);
VSTATE_ASSERT(VIMPL_TO_VNODE(new_vip), VS_LOADING);
+ mutex_exit(new_vp->v_interlock);
/* Rekey old node and put it onto its new hashlist. */
vip->vi_key = new_vcache_key;
@@ -1469,9 +1466,7 @@ vcache_rekey_exit(struct mount *mp, stru
/* Remove new node used as placeholder. */
SLIST_REMOVE(&vcache_hashtab[new_hash & vcache_hashmask],
new_vip, vnode_impl, vi_hash);
- VSTATE_CHANGE(new_vp, VS_LOADING, VS_RECLAIMED);
- mutex_exit(&vcache_lock);
- vrelel(new_vp, 0);
+ vcache_dealloc(new_vip);
}
/*
