1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 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 __exclusive_cache_line 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 != 0) 97 return (error); 98 if (vp->v_hash != hash || 99 (fn != NULL && fn(vp, arg))) { 100 vput(vp); 101 /* Restart the bucket walk. */ 102 break; 103 } 104 *vpp = vp; 105 return (0); 106 } 107 if (vp == NULL) { 108 rw_runlock(&vfs_hash_lock); 109 *vpp = NULL; 110 return (0); 111 } 112 } 113 } 114 115 void 116 vfs_hash_ref(const struct mount *mp, u_int hash, struct thread *td, 117 struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg) 118 { 119 struct vnode *vp; 120 121 while (1) { 122 rw_rlock(&vfs_hash_lock); 123 LIST_FOREACH(vp, vfs_hash_bucket(mp, hash), v_hashlist) { 124 if (vp->v_hash != hash) 125 continue; 126 if (vp->v_mount != mp) 127 continue; 128 if (fn != NULL && fn(vp, arg)) 129 continue; 130 vhold(vp); 131 rw_runlock(&vfs_hash_lock); 132 vref(vp); 133 vdrop(vp); 134 *vpp = vp; 135 return; 136 } 137 if (vp == NULL) { 138 rw_runlock(&vfs_hash_lock); 139 *vpp = NULL; 140 return; 141 } 142 } 143 } 144 145 void 146 vfs_hash_remove(struct vnode *vp) 147 { 148 149 rw_wlock(&vfs_hash_lock); 150 LIST_REMOVE(vp, v_hashlist); 151 rw_wunlock(&vfs_hash_lock); 152 } 153 154 int 155 vfs_hash_insert(struct vnode *vp, u_int hash, int flags, struct thread *td, 156 struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg) 157 { 158 struct vnode *vp2; 159 enum vgetstate vs; 160 int error; 161 162 *vpp = NULL; 163 while (1) { 164 rw_wlock(&vfs_hash_lock); 165 LIST_FOREACH(vp2, 166 vfs_hash_bucket(vp->v_mount, hash), v_hashlist) { 167 if (vp2->v_hash != hash) 168 continue; 169 if (vp2->v_mount != vp->v_mount) 170 continue; 171 if (fn != NULL && fn(vp2, arg)) 172 continue; 173 vs = vget_prep(vp2); 174 rw_wunlock(&vfs_hash_lock); 175 error = vget_finish(vp2, flags, vs); 176 if (error == ENOENT && (flags & LK_NOWAIT) == 0) 177 break; 178 rw_wlock(&vfs_hash_lock); 179 LIST_INSERT_HEAD(&vfs_hash_side, vp, v_hashlist); 180 rw_wunlock(&vfs_hash_lock); 181 vgone(vp); 182 vput(vp); 183 if (!error) 184 *vpp = vp2; 185 return (error); 186 } 187 if (vp2 == NULL) 188 break; 189 } 190 vp->v_hash = hash; 191 LIST_INSERT_HEAD(vfs_hash_bucket(vp->v_mount, hash), vp, v_hashlist); 192 rw_wunlock(&vfs_hash_lock); 193 return (0); 194 } 195 196 void 197 vfs_hash_rehash(struct vnode *vp, u_int hash) 198 { 199 ASSERT_VOP_ELOCKED(vp, "rehash requires excl lock"); 200 201 rw_wlock(&vfs_hash_lock); 202 LIST_REMOVE(vp, v_hashlist); 203 LIST_INSERT_HEAD(vfs_hash_bucket(vp->v_mount, hash), vp, v_hashlist); 204 vp->v_hash = hash; 205 rw_wunlock(&vfs_hash_lock); 206 } 207 208 void 209 vfs_hash_changesize(u_long newmaxvnodes) 210 { 211 struct vfs_hash_head *vfs_hash_newtbl, *vfs_hash_oldtbl; 212 u_long vfs_hash_newmask, vfs_hash_oldmask; 213 struct vnode *vp; 214 int i; 215 216 vfs_hash_newtbl = hashinit(newmaxvnodes, M_VFS_HASH, 217 &vfs_hash_newmask); 218 /* If same hash table size, nothing to do */ 219 if (vfs_hash_mask == vfs_hash_newmask) { 220 free(vfs_hash_newtbl, M_VFS_HASH); 221 return; 222 } 223 /* 224 * Move everything from the old hash table to the new table. 225 * None of the vnodes in the table can be recycled because to 226 * do so, they have to be removed from the hash table. 227 */ 228 rw_wlock(&vfs_hash_lock); 229 vfs_hash_oldtbl = vfs_hash_tbl; 230 vfs_hash_oldmask = vfs_hash_mask; 231 vfs_hash_tbl = vfs_hash_newtbl; 232 vfs_hash_mask = vfs_hash_newmask; 233 for (i = 0; i <= vfs_hash_oldmask; i++) { 234 while ((vp = LIST_FIRST(&vfs_hash_oldtbl[i])) != NULL) { 235 LIST_REMOVE(vp, v_hashlist); 236 LIST_INSERT_HEAD( 237 vfs_hash_bucket(vp->v_mount, vp->v_hash), 238 vp, v_hashlist); 239 } 240 } 241 rw_wunlock(&vfs_hash_lock); 242 free(vfs_hash_oldtbl, M_VFS_HASH); 243 } 244