vfs_hash.c revision 143680
1143561Sphk/*- 2143561Sphk * Copyright (c) 2005 Poul-Henning Kamp 3143561Sphk * All rights reserved. 4143561Sphk * 5143561Sphk * Redistribution and use in source and binary forms, with or without 6143561Sphk * modification, are permitted provided that the following conditions 7143561Sphk * are met: 8143561Sphk * 1. Redistributions of source code must retain the above copyright 9143561Sphk * notice, this list of conditions and the following disclaimer. 10143561Sphk * 2. Redistributions in binary form must reproduce the above copyright 11143561Sphk * notice, this list of conditions and the following disclaimer in the 12143561Sphk * documentation and/or other materials provided with the distribution. 13143561Sphk * 14143561Sphk * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15143561Sphk * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16143561Sphk * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17143561Sphk * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18143561Sphk * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19143561Sphk * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20143561Sphk * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21143561Sphk * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22143561Sphk * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23143561Sphk * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24143561Sphk * SUCH DAMAGE. 25143561Sphk * 26143561Sphk */ 27143561Sphk 28143561Sphk#include <sys/cdefs.h> 29143561Sphk__FBSDID("$FreeBSD: head/sys/kern/vfs_hash.c 143680 2005-03-16 07:35:06Z phk $"); 30143561Sphk 31143561Sphk#include <sys/param.h> 32143561Sphk#include <sys/systm.h> 33143561Sphk#include <sys/kernel.h> 34143561Sphk#include <sys/malloc.h> 35143680Sphk#include <sys/mount.h> 36143561Sphk#include <sys/vnode.h> 37143561Sphk 38143561Sphkstatic MALLOC_DEFINE(M_VFS_HASH, "VFS hash", "VFS hash table"); 39143561Sphk 40143680Sphkstatic LIST_HEAD(vfs_hash_head, vnode) *vfs_hash_tbl; 41143680Sphkstatic LIST_HEAD(,vnode) vfs_hash_side; 42143561Sphkstatic u_long vfs_hash_mask; 43143561Sphkstatic struct mtx vfs_hash_mtx; 44143561Sphk 45143561Sphkstatic void 46143561Sphkvfs_hashinit(void *dummy __unused) 47143561Sphk{ 48143561Sphk 49143561Sphk vfs_hash_tbl = hashinit(desiredvnodes, M_VFS_HASH, &vfs_hash_mask); 50143561Sphk mtx_init(&vfs_hash_mtx, "vfs hash", NULL, MTX_DEF); 51143680Sphk LIST_INIT(&vfs_hash_side); 52143561Sphk} 53143561Sphk 54143561Sphk/* Must be SI_ORDER_SECOND so desiredvnodes is available */ 55143561SphkSYSINIT(vfs_hash, SI_SUB_VFS, SI_ORDER_SECOND, vfs_hashinit, NULL) 56143561Sphk 57143680Sphkstatic struct vfs_hash_head * 58143680Sphkvfs_hash_index(struct mount *mp, u_int hash) 59143680Sphk{ 60143680Sphk 61143680Sphk return(&vfs_hash_tbl[(hash + mp->mnt_hashseed) & vfs_hash_mask]); 62143680Sphk} 63143680Sphk 64143561Sphkint 65143561Sphkvfs_hash_get(struct mount *mp, u_int hash, int flags, struct thread *td, struct vnode **vpp) 66143561Sphk{ 67143561Sphk struct vnode *vp; 68143561Sphk int error; 69143561Sphk 70143561Sphk while (1) { 71143561Sphk mtx_lock(&vfs_hash_mtx); 72143680Sphk LIST_FOREACH(vp, vfs_hash_index(mp, hash), v_hashlist) { 73143561Sphk if (vp->v_hash != hash) 74143561Sphk continue; 75143561Sphk if (vp->v_mount != mp) 76143561Sphk continue; 77143561Sphk VI_LOCK(vp); 78143561Sphk mtx_unlock(&vfs_hash_mtx); 79143561Sphk error = vget(vp, flags | LK_INTERLOCK, td); 80143561Sphk if (error == ENOENT) 81143561Sphk break; 82143561Sphk if (error) 83143561Sphk return (error); 84143561Sphk *vpp = vp; 85143561Sphk return (0); 86143561Sphk } 87143561Sphk if (vp == NULL) { 88143561Sphk mtx_unlock(&vfs_hash_mtx); 89143561Sphk *vpp = NULL; 90143561Sphk return (0); 91143561Sphk } 92143561Sphk } 93143561Sphk} 94143561Sphk 95143561Sphkvoid 96143561Sphkvfs_hash_remove(struct vnode *vp) 97143561Sphk{ 98143561Sphk 99143561Sphk mtx_lock(&vfs_hash_mtx); 100143561Sphk LIST_REMOVE(vp, v_hashlist); 101143561Sphk mtx_unlock(&vfs_hash_mtx); 102143561Sphk} 103143561Sphk 104143561Sphkint 105143561Sphkvfs_hash_insert(struct vnode *vp, u_int hash, int flags, struct thread *td, struct vnode **vpp) 106143561Sphk{ 107143561Sphk struct vnode *vp2; 108143561Sphk int error; 109143561Sphk 110143619Sphk lockmgr(vp->v_vnlock, LK_EXCLUSIVE, NULL, td); 111143619Sphk *vpp = NULL; 112143561Sphk while (1) { 113143561Sphk mtx_lock(&vfs_hash_mtx); 114143561Sphk LIST_FOREACH(vp2, 115143680Sphk vfs_hash_index(vp->v_mount, hash), v_hashlist) { 116143561Sphk if (vp2->v_hash != hash) 117143561Sphk continue; 118143561Sphk if (vp2->v_mount != vp->v_mount) 119143561Sphk continue; 120143561Sphk VI_LOCK(vp2); 121143561Sphk mtx_unlock(&vfs_hash_mtx); 122143561Sphk error = vget(vp2, flags | LK_INTERLOCK, td); 123143561Sphk if (error == ENOENT) 124143561Sphk break; 125143680Sphk mtx_lock(&vfs_hash_mtx); 126143680Sphk LIST_INSERT_HEAD(&vfs_hash_side, vp, v_hashlist); 127143680Sphk mtx_unlock(&vfs_hash_mtx); 128143663Sphk vput(vp); 129143663Sphk if (!error) 130143663Sphk *vpp = vp2; 131143663Sphk return (error); 132143561Sphk } 133143561Sphk if (vp2 == NULL) 134143561Sphk break; 135143561Sphk 136143561Sphk } 137143561Sphk vp->v_hash = hash; 138143680Sphk LIST_INSERT_HEAD(vfs_hash_index(vp->v_mount, hash), vp, v_hashlist); 139143561Sphk mtx_unlock(&vfs_hash_mtx); 140143561Sphk return (0); 141143561Sphk} 142143561Sphk 143143561Sphkvoid 144143561Sphkvfs_hash_rehash(struct vnode *vp, u_int hash) 145143561Sphk{ 146143561Sphk 147143561Sphk mtx_lock(&vfs_hash_mtx); 148143561Sphk LIST_REMOVE(vp, v_hashlist); 149143561Sphk LIST_INSERT_HEAD(&vfs_hash_tbl[hash & vfs_hash_mask], vp, v_hashlist); 150143561Sphk vp->v_hash = hash; 151143561Sphk mtx_unlock(&vfs_hash_mtx); 152143561Sphk} 153