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 enum vgetstate vs; 80 int error; 81 82 while (1) { 83 rw_rlock(&vfs_hash_lock); 84 LIST_FOREACH(vp, vfs_hash_bucket(mp, hash), v_hashlist) { 85 if (vp->v_hash != hash) 86 continue; 87 if (vp->v_mount != mp) 88 continue; 89 if (fn != NULL && fn(vp, arg)) 90 continue; 91 vs = vget_prep(vp); 92 rw_runlock(&vfs_hash_lock); 93 error = vget_finish(vp, flags, vs); 94 if (error == ENOENT && (flags & LK_NOWAIT) == 0) 95 break; 96 if (error) 97 return (error); 98 *vpp = vp; 99 return (0); 100 } 101 if (vp == NULL) { 102 rw_runlock(&vfs_hash_lock); 103 *vpp = NULL; 104 return (0); 105 } 106 } 107 } 108 109 void 110 vfs_hash_ref(const struct mount *mp, u_int hash, struct thread *td, 111 struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg) 112 { 113 struct vnode *vp; 114 115 while (1) { 116 rw_rlock(&vfs_hash_lock); 117 LIST_FOREACH(vp, vfs_hash_bucket(mp, hash), v_hashlist) { 118 if (vp->v_hash != hash) 119 continue; 120 if (vp->v_mount != mp) 121 continue; 122 if (fn != NULL && fn(vp, arg)) 123 continue; 124 vhold(vp); 125 rw_runlock(&vfs_hash_lock); 126 vref(vp); 127 vdrop(vp); 128 *vpp = vp; 129 return; 130 } 131 if (vp == NULL) { 132 rw_runlock(&vfs_hash_lock); 133 *vpp = NULL; 134 return; 135 } 136 } 137 } 138 139 void 140 vfs_hash_remove(struct vnode *vp) 141 { 142 143 rw_wlock(&vfs_hash_lock); 144 LIST_REMOVE(vp, v_hashlist); 145 rw_wunlock(&vfs_hash_lock); 146 } 147 148 int 149 vfs_hash_insert(struct vnode *vp, u_int hash, int flags, struct thread *td, 150 struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg) 151 { 152 struct vnode *vp2; 153 enum vgetstate vs; 154 int error; 155 156 *vpp = NULL; 157 while (1) { 158 rw_wlock(&vfs_hash_lock); 159 LIST_FOREACH(vp2, 160 vfs_hash_bucket(vp->v_mount, hash), v_hashlist) { 161 if (vp2->v_hash != hash) 162 continue; 163 if (vp2->v_mount != vp->v_mount) 164 continue; 165 if (fn != NULL && fn(vp2, arg)) 166 continue; 167 vs = vget_prep(vp2); 168 rw_wunlock(&vfs_hash_lock); 169 error = vget_finish(vp2, flags, vs); 170 if (error == ENOENT && (flags & LK_NOWAIT) == 0) 171 break; 172 rw_wlock(&vfs_hash_lock); 173 LIST_INSERT_HEAD(&vfs_hash_side, vp, v_hashlist); 174 rw_wunlock(&vfs_hash_lock); 175 vput(vp); 176 if (!error) 177 *vpp = vp2; 178 return (error); 179 } 180 if (vp2 == NULL) 181 break; 182 183 } 184 vp->v_hash = hash; 185 LIST_INSERT_HEAD(vfs_hash_bucket(vp->v_mount, hash), vp, v_hashlist); 186 rw_wunlock(&vfs_hash_lock); 187 return (0); 188 } 189 190 void 191 vfs_hash_rehash(struct vnode *vp, u_int hash) 192 { 193 194 rw_wlock(&vfs_hash_lock); 195 LIST_REMOVE(vp, v_hashlist); 196 LIST_INSERT_HEAD(vfs_hash_bucket(vp->v_mount, hash), vp, v_hashlist); 197 vp->v_hash = hash; 198 rw_wunlock(&vfs_hash_lock); 199 } 200 201 void 202 vfs_hash_changesize(u_long newmaxvnodes) 203 { 204 struct vfs_hash_head *vfs_hash_newtbl, *vfs_hash_oldtbl; 205 u_long vfs_hash_newmask, vfs_hash_oldmask; 206 struct vnode *vp; 207 int i; 208 209 vfs_hash_newtbl = hashinit(newmaxvnodes, M_VFS_HASH, 210 &vfs_hash_newmask); 211 /* If same hash table size, nothing to do */ 212 if (vfs_hash_mask == vfs_hash_newmask) { 213 free(vfs_hash_newtbl, M_VFS_HASH); 214 return; 215 } 216 /* 217 * Move everything from the old hash table to the new table. 218 * None of the vnodes in the table can be recycled because to 219 * do so, they have to be removed from the hash table. 220 */ 221 rw_wlock(&vfs_hash_lock); 222 vfs_hash_oldtbl = vfs_hash_tbl; 223 vfs_hash_oldmask = vfs_hash_mask; 224 vfs_hash_tbl = vfs_hash_newtbl; 225 vfs_hash_mask = vfs_hash_newmask; 226 for (i = 0; i <= vfs_hash_oldmask; i++) { 227 while ((vp = LIST_FIRST(&vfs_hash_oldtbl[i])) != NULL) { 228 LIST_REMOVE(vp, v_hashlist); 229 LIST_INSERT_HEAD( 230 vfs_hash_bucket(vp->v_mount, vp->v_hash), 231 vp, v_hashlist); 232 } 233 } 234 rw_wunlock(&vfs_hash_lock); 235 free(vfs_hash_oldtbl, M_VFS_HASH); 236 } 237