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