1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2005 Poul-Henning Kamp 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 * 28 */ 29 30 #include <sys/cdefs.h> 31 __FBSDID("$FreeBSD$"); 32 33 #include <sys/param.h> 34 #include <sys/systm.h> 35 #include <sys/kernel.h> 36 #include <sys/malloc.h> 37 #include <sys/mount.h> 38 #include <sys/rwlock.h> 39 #include <sys/vnode.h> 40 41 static MALLOC_DEFINE(M_VFS_HASH, "vfs_hash", "VFS hash table"); 42 43 static LIST_HEAD(vfs_hash_head, vnode) *vfs_hash_tbl; 44 static LIST_HEAD(,vnode) vfs_hash_side; 45 static u_long vfs_hash_mask; 46 static struct rwlock vfs_hash_lock; 47 48 static void 49 vfs_hashinit(void *dummy __unused) 50 { 51 52 vfs_hash_tbl = hashinit(desiredvnodes, M_VFS_HASH, &vfs_hash_mask); 53 rw_init(&vfs_hash_lock, "vfs hash"); 54 LIST_INIT(&vfs_hash_side); 55 } 56 57 /* Must be SI_ORDER_SECOND so desiredvnodes is available */ 58 SYSINIT(vfs_hash, SI_SUB_VFS, SI_ORDER_SECOND, vfs_hashinit, NULL); 59 60 u_int 61 vfs_hash_index(struct vnode *vp) 62 { 63 64 return (vp->v_hash + vp->v_mount->mnt_hashseed); 65 } 66 67 static struct vfs_hash_head * 68 vfs_hash_bucket(const struct mount *mp, u_int hash) 69 { 70 71 return (&vfs_hash_tbl[(hash + mp->mnt_hashseed) & vfs_hash_mask]); 72 } 73 74 int 75 vfs_hash_get(const struct mount *mp, u_int hash, int flags, struct thread *td, 76 struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg) 77 { 78 struct vnode *vp; 79 int error; 80 81 while (1) { 82 rw_rlock(&vfs_hash_lock); 83 LIST_FOREACH(vp, vfs_hash_bucket(mp, hash), v_hashlist) { 84 if (vp->v_hash != hash) 85 continue; 86 if (vp->v_mount != mp) 87 continue; 88 if (fn != NULL && fn(vp, arg)) 89 continue; 90 vhold(vp); 91 rw_runlock(&vfs_hash_lock); 92 error = vget(vp, flags | LK_VNHELD, td); 93 if (error == ENOENT && (flags & LK_NOWAIT) == 0) 94 break; 95 if (error) 96 return (error); 97 *vpp = vp; 98 return (0); 99 } 100 if (vp == NULL) { 101 rw_runlock(&vfs_hash_lock); 102 *vpp = NULL; 103 return (0); 104 } 105 } 106 } 107 108 void 109 vfs_hash_ref(const struct mount *mp, u_int hash, struct thread *td, 110 struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg) 111 { 112 struct vnode *vp; 113 114 while (1) { 115 rw_rlock(&vfs_hash_lock); 116 LIST_FOREACH(vp, vfs_hash_bucket(mp, hash), v_hashlist) { 117 if (vp->v_hash != hash) 118 continue; 119 if (vp->v_mount != mp) 120 continue; 121 if (fn != NULL && fn(vp, arg)) 122 continue; 123 vhold(vp); 124 rw_runlock(&vfs_hash_lock); 125 vref(vp); 126 vdrop(vp); 127 *vpp = vp; 128 return; 129 } 130 if (vp == NULL) { 131 rw_runlock(&vfs_hash_lock); 132 *vpp = NULL; 133 return; 134 } 135 } 136 } 137 138 void 139 vfs_hash_remove(struct vnode *vp) 140 { 141 142 rw_wlock(&vfs_hash_lock); 143 LIST_REMOVE(vp, v_hashlist); 144 rw_wunlock(&vfs_hash_lock); 145 } 146 147 int 148 vfs_hash_insert(struct vnode *vp, u_int hash, int flags, struct thread *td, 149 struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg) 150 { 151 struct vnode *vp2; 152 int error; 153 154 *vpp = NULL; 155 while (1) { 156 rw_wlock(&vfs_hash_lock); 157 LIST_FOREACH(vp2, 158 vfs_hash_bucket(vp->v_mount, hash), v_hashlist) { 159 if (vp2->v_hash != hash) 160 continue; 161 if (vp2->v_mount != vp->v_mount) 162 continue; 163 if (fn != NULL && fn(vp2, arg)) 164 continue; 165 vhold(vp2); 166 rw_wunlock(&vfs_hash_lock); 167 error = vget(vp2, flags | LK_VNHELD, td); 168 if (error == ENOENT && (flags & LK_NOWAIT) == 0) 169 break; 170 rw_wlock(&vfs_hash_lock); 171 LIST_INSERT_HEAD(&vfs_hash_side, vp, v_hashlist); 172 rw_wunlock(&vfs_hash_lock); 173 vput(vp); 174 if (!error) 175 *vpp = vp2; 176 return (error); 177 } 178 if (vp2 == NULL) 179 break; 180 181 } 182 vp->v_hash = hash; 183 LIST_INSERT_HEAD(vfs_hash_bucket(vp->v_mount, hash), vp, v_hashlist); 184 rw_wunlock(&vfs_hash_lock); 185 return (0); 186 } 187 188 void 189 vfs_hash_rehash(struct vnode *vp, u_int hash) 190 { 191 192 rw_wlock(&vfs_hash_lock); 193 LIST_REMOVE(vp, v_hashlist); 194 LIST_INSERT_HEAD(vfs_hash_bucket(vp->v_mount, hash), vp, v_hashlist); 195 vp->v_hash = hash; 196 rw_wunlock(&vfs_hash_lock); 197 } 198 199 void 200 vfs_hash_changesize(int newmaxvnodes) 201 { 202 struct vfs_hash_head *vfs_hash_newtbl, *vfs_hash_oldtbl; 203 u_long vfs_hash_newmask, vfs_hash_oldmask; 204 struct vnode *vp; 205 int i; 206 207 vfs_hash_newtbl = hashinit(newmaxvnodes, M_VFS_HASH, 208 &vfs_hash_newmask); 209 /* If same hash table size, nothing to do */ 210 if (vfs_hash_mask == vfs_hash_newmask) { 211 free(vfs_hash_newtbl, M_VFS_HASH); 212 return; 213 } 214 /* 215 * Move everything from the old hash table to the new table. 216 * None of the vnodes in the table can be recycled because to 217 * do so, they have to be removed from the hash table. 218 */ 219 rw_wlock(&vfs_hash_lock); 220 vfs_hash_oldtbl = vfs_hash_tbl; 221 vfs_hash_oldmask = vfs_hash_mask; 222 vfs_hash_tbl = vfs_hash_newtbl; 223 vfs_hash_mask = vfs_hash_newmask; 224 for (i = 0; i <= vfs_hash_oldmask; i++) { 225 while ((vp = LIST_FIRST(&vfs_hash_oldtbl[i])) != NULL) { 226 LIST_REMOVE(vp, v_hashlist); 227 LIST_INSERT_HEAD( 228 vfs_hash_bucket(vp->v_mount, vp->v_hash), 229 vp, v_hashlist); 230 } 231 } 232 rw_wunlock(&vfs_hash_lock); 233 free(vfs_hash_oldtbl, M_VFS_HASH); 234 } 235