freebsd-dev/sys/kern/vfs_hash.c
2005-03-15 08:07:07 +00:00

151 lines
4.0 KiB
C

/*-
* Copyright (c) 2005 Poul-Henning Kamp
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/vnode.h>
static MALLOC_DEFINE(M_VFS_HASH, "VFS hash", "VFS hash table");
static LIST_HEAD(vfs_hashhead, vnode) *vfs_hash_tbl;
static u_long vfs_hash_mask;
static struct mtx vfs_hash_mtx;
static void
vfs_hashinit(void *dummy __unused)
{
vfs_hash_tbl = hashinit(desiredvnodes, M_VFS_HASH, &vfs_hash_mask);
mtx_init(&vfs_hash_mtx, "vfs hash", NULL, MTX_DEF);
}
/* Must be SI_ORDER_SECOND so desiredvnodes is available */
SYSINIT(vfs_hash, SI_SUB_VFS, SI_ORDER_SECOND, vfs_hashinit, NULL)
int
vfs_hash_get(struct mount *mp, u_int hash, int flags, struct thread *td, struct vnode **vpp)
{
struct vnode *vp;
int error;
while (1) {
mtx_lock(&vfs_hash_mtx);
LIST_FOREACH(vp,
&vfs_hash_tbl[hash & vfs_hash_mask], v_hashlist) {
if (vp->v_hash != hash)
continue;
if (vp->v_mount != mp)
continue;
VI_LOCK(vp);
mtx_unlock(&vfs_hash_mtx);
error = vget(vp, flags | LK_INTERLOCK, td);
if (error == ENOENT)
break;
if (error)
return (error);
*vpp = vp;
return (0);
}
if (vp == NULL) {
mtx_unlock(&vfs_hash_mtx);
*vpp = NULL;
return (0);
}
}
}
void
vfs_hash_remove(struct vnode *vp)
{
mtx_lock(&vfs_hash_mtx);
VI_LOCK(vp);
VNASSERT(vp->v_iflag & VI_HASHED, vp, ("vfs_hash_remove: not hashed"));
LIST_REMOVE(vp, v_hashlist);
vp->v_iflag &= ~VI_HASHED;
VI_UNLOCK(vp);
mtx_unlock(&vfs_hash_mtx);
}
int
vfs_hash_insert(struct vnode *vp, u_int hash, int flags, struct thread *td, struct vnode **vpp)
{
struct vnode *vp2;
int error;
lockmgr(vp->v_vnlock, LK_EXCLUSIVE, NULL, td);
*vpp = NULL;
while (1) {
mtx_lock(&vfs_hash_mtx);
LIST_FOREACH(vp2,
&vfs_hash_tbl[hash & vfs_hash_mask], v_hashlist) {
if (vp2->v_hash != hash)
continue;
if (vp2->v_mount != vp->v_mount)
continue;
VI_LOCK(vp2);
mtx_unlock(&vfs_hash_mtx);
error = vget(vp2, flags | LK_INTERLOCK, td);
if (error == ENOENT)
break;
if (error)
return (error);
*vpp = vp2;
return (0);
}
if (vp2 == NULL)
break;
}
VI_LOCK(vp);
VNASSERT(!(vp->v_iflag & VI_HASHED), vp,
("vfs_hash_insert: already hashed"));
vp->v_hash = hash;
LIST_INSERT_HEAD(&vfs_hash_tbl[hash & vfs_hash_mask], vp, v_hashlist);
vp->v_iflag |= VI_HASHED;
VI_UNLOCK(vp);
mtx_unlock(&vfs_hash_mtx);
return (0);
}
void
vfs_hash_rehash(struct vnode *vp, u_int hash)
{
mtx_lock(&vfs_hash_mtx);
VNASSERT(vp->v_iflag & VI_HASHED, vp, ("vfs_hash_rehash: not hashed"));
LIST_REMOVE(vp, v_hashlist);
LIST_INSERT_HEAD(&vfs_hash_tbl[hash & vfs_hash_mask], vp, v_hashlist);
vp->v_hash = hash;
mtx_unlock(&vfs_hash_mtx);
}