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Use mutexes to protect the hash lists instead of tsleep/wakeup.

This commit is contained in:
hannken 2011-08-13 10:48:14 +00:00
parent 154895972c
commit 1147247693
1 changed files with 24 additions and 54 deletions
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78
sys/fs/union/union_subr.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: union_subr.c,v 1.48 2011/08/12 17:41:17 hannken Exp $ */
/* $NetBSD: union_subr.c,v 1.49 2011/08/13 10:48:14 hannken Exp $ */
/*
* Copyright (c) 1994
@ -72,7 +72,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: union_subr.c,v 1.48 2011/08/12 17:41:17 hannken Exp $");
__KERNEL_RCSID(0, "$NetBSD: union_subr.c,v 1.49 2011/08/13 10:48:14 hannken Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@ -103,10 +103,8 @@ __KERNEL_RCSID(0, "$NetBSD: union_subr.c,v 1.48 2011/08/12 17:41:17 hannken Exp
(((((unsigned long) (u)) + ((unsigned long) l)) >> 8) & (NHASH-1))
static LIST_HEAD(unhead, union_node) unhead[NHASH];
static int unvplock[NHASH];
static kmutex_t unheadlock[NHASH];
static int union_list_lock(int);
static void union_list_unlock(int);
void union_updatevp(struct union_node *, struct vnode *, struct vnode *);
static int union_relookup(struct union_mount *, struct vnode *,
struct vnode **, struct componentname *,
@ -121,9 +119,10 @@ union_init(void)
{
int i;
for (i = 0; i < NHASH; i++)
for (i = 0; i < NHASH; i++) {
LIST_INIT(&unhead[i]);
memset(unvplock, 0, sizeof(unvplock));
mutex_init(&unheadlock[i], MUTEX_DEFAULT, IPL_NONE);
}
}
/*
@ -132,38 +131,15 @@ union_init(void)
void
union_done(void)
{
int i;
for (i = 0; i < NHASH; i++)
mutex_destroy(&unheadlock[i]);
/* Make sure to unset the readdir hook. */
vn_union_readdir_hook = NULL;
}
static int
union_list_lock(int ix)
{
if (unvplock[ix] & UN_LOCKED) {
unvplock[ix] |= UN_WANTED;
(void) tsleep(&unvplock[ix], PINOD, "unionlk", 0);
return (1);
}
unvplock[ix] |= UN_LOCKED;
return (0);
}
static void
union_list_unlock(int ix)
{
unvplock[ix] &= ~UN_LOCKED;
if (unvplock[ix] & UN_WANTED) {
unvplock[ix] &= ~UN_WANTED;
wakeup(&unvplock[ix]);
}
}
void
union_updatevp(struct union_node *un, struct vnode *uppervp,
struct vnode *lowervp)
@ -186,11 +162,9 @@ union_updatevp(struct union_node *un, struct vnode *uppervp,
}
if (lhash != uhash)
while (union_list_lock(lhash))
continue;
mutex_enter(&unheadlock[lhash]);
while (union_list_lock(uhash))
continue;
mutex_enter(&unheadlock[uhash]);
if (ohash != nhash || !docache) {
if (un->un_flags & UN_CACHED) {
@ -200,7 +174,7 @@ union_updatevp(struct union_node *un, struct vnode *uppervp,
}
if (ohash != nhash)
union_list_unlock(ohash);
mutex_exit(&unheadlock[ohash]);
if (un->un_lowervp != lowervp) {
if (un->un_lowervp) {
@ -237,7 +211,7 @@ union_updatevp(struct union_node *un, struct vnode *uppervp,
un->un_flags |= UN_CACHED;
}
union_list_unlock(nhash);
mutex_exit(&unheadlock[nhash]);
}
void
@ -394,8 +368,7 @@ loop:
break;
}
while (union_list_lock(hash))
continue;
mutex_enter(&unheadlock[hash]);
for (un = unhead[hash].lh_first; un != 0;
un = un->un_cache.le_next) {
@ -407,14 +380,14 @@ loop:
vp = UNIONTOV(un);
mutex_enter(vp->v_interlock);
if (vget(vp, 0)) {
union_list_unlock(hash);
mutex_exit(&unheadlock[hash]);
goto loop;
}
break;
}
}
union_list_unlock(hash);
mutex_exit(&unheadlock[hash]);
if (un)
break;
@ -528,8 +501,7 @@ loop:
}
if (docache) {
while (union_list_lock(hash))
continue;
mutex_enter(&unheadlock[hash]);
LIST_FOREACH(un1, &unhead[hash], un_cache) {
if (un1->un_lowervp == lowervp &&
un1->un_uppervp == uppervp &&
@ -538,7 +510,7 @@ loop:
* Another thread beat us, push back freshly
* allocated vnode and retry.
*/
union_list_unlock(hash);
mutex_exit(&unheadlock[hash]);
ungetnewvnode(*vpp);
goto loop;
}
@ -603,7 +575,7 @@ loop:
out:
if (docache)
union_list_unlock(hash);
mutex_exit(&unheadlock[hash]);
return (error);
}
@ -616,13 +588,12 @@ union_freevp(struct vnode *vp)
hash = UNION_HASH(un->un_uppervp, un->un_lowervp);
while (union_list_lock(hash))
continue;
mutex_enter(&unheadlock[hash]);
if (un->un_flags & UN_CACHED) {
un->un_flags &= ~UN_CACHED;
LIST_REMOVE(un, un_cache);
}
union_list_unlock(hash);
mutex_exit(&unheadlock[hash]);
if (un->un_pvp != NULLVP)
vrele(un->un_pvp);
@ -1060,13 +1031,12 @@ union_removed_upper(struct union_node *un)
hash = UNION_HASH(un->un_uppervp, un->un_lowervp);
while (union_list_lock(hash))
continue;
mutex_enter(&unheadlock[hash]);
if (un->un_flags & UN_CACHED) {
un->un_flags &= ~UN_CACHED;
LIST_REMOVE(un, un_cache);
}
union_list_unlock(hash);
mutex_exit(&unheadlock[hash]);
if (un->un_flags & UN_ULOCK) {
un->un_flags &= ~UN_ULOCK;