FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_hash.c
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: releng/11.1/sys/kern/vfs_hash.c 299412 2016-05-11 06:32:22Z kib $");
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 }
Cache object: 99f4612a20cfe977f9be90bce46d31df
|