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, struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg) 74 { 75 struct vnode *vp; 76 int error; 77 78 while (1) { 79 rw_rlock(&vfs_hash_lock); 80 LIST_FOREACH(vp, vfs_hash_bucket(mp, hash), v_hashlist) { 81 if (vp->v_hash != hash) 82 continue; 83 if (vp->v_mount != mp) 84 continue; 85 if (fn != NULL && fn(vp, arg)) 86 continue; 87 vhold(vp); 88 rw_runlock(&vfs_hash_lock); 89 error = vget(vp, flags | LK_VNHELD, td); 90 if (error == ENOENT && (flags & LK_NOWAIT) == 0) 91 break; 92 if (error) 93 return (error); 94 *vpp = vp; 95 return (0); 96 } 97 if (vp == NULL) { 98 rw_runlock(&vfs_hash_lock); 99 *vpp = NULL; 100 return (0); 101 } 102 } 103 } 104 105 void 106 vfs_hash_remove(struct vnode *vp) 107 { 108 109 rw_wlock(&vfs_hash_lock); 110 LIST_REMOVE(vp, v_hashlist); 111 rw_wunlock(&vfs_hash_lock); 112 } 113 114 int 115 vfs_hash_insert(struct vnode *vp, u_int hash, int flags, struct thread *td, struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg) 116 { 117 struct vnode *vp2; 118 int error; 119 120 *vpp = NULL; 121 while (1) { 122 rw_wlock(&vfs_hash_lock); 123 LIST_FOREACH(vp2, 124 vfs_hash_bucket(vp->v_mount, hash), v_hashlist) { 125 if (vp2->v_hash != hash) 126 continue; 127 if (vp2->v_mount != vp->v_mount) 128 continue; 129 if (fn != NULL && fn(vp2, arg)) 130 continue; 131 vhold(vp2); 132 rw_wunlock(&vfs_hash_lock); 133 error = vget(vp2, flags | LK_VNHELD, td); 134 if (error == ENOENT && (flags & LK_NOWAIT) == 0) 135 break; 136 rw_wlock(&vfs_hash_lock); 137 LIST_INSERT_HEAD(&vfs_hash_side, vp, v_hashlist); 138 rw_wunlock(&vfs_hash_lock); 139 vput(vp); 140 if (!error) 141 *vpp = vp2; 142 return (error); 143 } 144 if (vp2 == NULL) 145 break; 146 147 } 148 vp->v_hash = hash; 149 LIST_INSERT_HEAD(vfs_hash_bucket(vp->v_mount, hash), vp, v_hashlist); 150 rw_wunlock(&vfs_hash_lock); 151 return (0); 152 } 153 154 void 155 vfs_hash_rehash(struct vnode *vp, u_int hash) 156 { 157 158 rw_wlock(&vfs_hash_lock); 159 LIST_REMOVE(vp, v_hashlist); 160 LIST_INSERT_HEAD(vfs_hash_bucket(vp->v_mount, hash), vp, v_hashlist); 161 vp->v_hash = hash; 162 rw_wunlock(&vfs_hash_lock); 163 } 164 165 void 166 vfs_hash_changesize(int newmaxvnodes) 167 { 168 struct vfs_hash_head *vfs_hash_newtbl, *vfs_hash_oldtbl; 169 u_long vfs_hash_newmask, vfs_hash_oldmask; 170 struct vnode *vp; 171 int i; 172 173 vfs_hash_newtbl = hashinit(newmaxvnodes, M_VFS_HASH, 174 &vfs_hash_newmask); 175 /* If same hash table size, nothing to do */ 176 if (vfs_hash_mask == vfs_hash_newmask) { 177 free(vfs_hash_newtbl, M_VFS_HASH); 178 return; 179 } 180 /* 181 * Move everything from the old hash table to the new table. 182 * None of the vnodes in the table can be recycled because to 183 * do so, they have to be removed from the hash table. 184 */ 185 rw_wlock(&vfs_hash_lock); 186 vfs_hash_oldtbl = vfs_hash_tbl; 187 vfs_hash_oldmask = vfs_hash_mask; 188 vfs_hash_tbl = vfs_hash_newtbl; 189 vfs_hash_mask = vfs_hash_newmask; 190 for (i = 0; i <= vfs_hash_oldmask; i++) { 191 while ((vp = LIST_FIRST(&vfs_hash_oldtbl[i])) != NULL) { 192 LIST_REMOVE(vp, v_hashlist); 193 LIST_INSERT_HEAD( 194 vfs_hash_bucket(vp->v_mount, vp->v_hash), 195 vp, v_hashlist); 196 } 197 } 198 rw_wunlock(&vfs_hash_lock); 199 free(vfs_hash_oldtbl, M_VFS_HASH); 200 } 201