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/6.0/sys/kern/vfs_hash.c 150049 2005-09-12 15:53:58Z tegge $");
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/vnode.h>
37
38 static MALLOC_DEFINE(M_VFS_HASH, "VFS hash", "VFS hash table");
39
40 static LIST_HEAD(vfs_hash_head, vnode) *vfs_hash_tbl;
41 static LIST_HEAD(,vnode) vfs_hash_side;
42 static u_long vfs_hash_mask;
43 static struct mtx vfs_hash_mtx;
44
45 static void
46 vfs_hashinit(void *dummy __unused)
47 {
48
49 vfs_hash_tbl = hashinit(desiredvnodes, M_VFS_HASH, &vfs_hash_mask);
50 mtx_init(&vfs_hash_mtx, "vfs hash", NULL, MTX_DEF);
51 LIST_INIT(&vfs_hash_side);
52 }
53
54 /* Must be SI_ORDER_SECOND so desiredvnodes is available */
55 SYSINIT(vfs_hash, SI_SUB_VFS, SI_ORDER_SECOND, vfs_hashinit, NULL)
56
57 static struct vfs_hash_head *
58 vfs_hash_index(struct mount *mp, u_int hash)
59 {
60
61 return(&vfs_hash_tbl[(hash + mp->mnt_hashseed) & vfs_hash_mask]);
62 }
63
64 int
65 vfs_hash_get(struct mount *mp, u_int hash, int flags, struct thread *td, struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg)
66 {
67 struct vnode *vp;
68 int error;
69
70 while (1) {
71 mtx_lock(&vfs_hash_mtx);
72 LIST_FOREACH(vp, vfs_hash_index(mp, hash), v_hashlist) {
73 if (vp->v_hash != hash)
74 continue;
75 if (vp->v_mount != mp)
76 continue;
77 if (fn != NULL && fn(vp, arg))
78 continue;
79 VI_LOCK(vp);
80 mtx_unlock(&vfs_hash_mtx);
81 error = vget(vp, flags | LK_INTERLOCK, td);
82 if (error == ENOENT && (flags & LK_NOWAIT) == 0)
83 break;
84 if (error)
85 return (error);
86 *vpp = vp;
87 return (0);
88 }
89 if (vp == NULL) {
90 mtx_unlock(&vfs_hash_mtx);
91 *vpp = NULL;
92 return (0);
93 }
94 }
95 }
96
97 void
98 vfs_hash_remove(struct vnode *vp)
99 {
100
101 mtx_lock(&vfs_hash_mtx);
102 LIST_REMOVE(vp, v_hashlist);
103 mtx_unlock(&vfs_hash_mtx);
104 }
105
106 int
107 vfs_hash_insert(struct vnode *vp, u_int hash, int flags, struct thread *td, struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg)
108 {
109 struct vnode *vp2;
110 int error;
111
112 lockmgr(vp->v_vnlock, flags & LK_TYPE_MASK, NULL, td);
113 *vpp = NULL;
114 while (1) {
115 mtx_lock(&vfs_hash_mtx);
116 LIST_FOREACH(vp2,
117 vfs_hash_index(vp->v_mount, hash), v_hashlist) {
118 if (vp2->v_hash != hash)
119 continue;
120 if (vp2->v_mount != vp->v_mount)
121 continue;
122 if (fn != NULL && fn(vp2, arg))
123 continue;
124 VI_LOCK(vp2);
125 mtx_unlock(&vfs_hash_mtx);
126 error = vget(vp2, flags | LK_INTERLOCK, td);
127 if (error == ENOENT && (flags & LK_NOWAIT) == 0)
128 break;
129 mtx_lock(&vfs_hash_mtx);
130 LIST_INSERT_HEAD(&vfs_hash_side, vp, v_hashlist);
131 mtx_unlock(&vfs_hash_mtx);
132 vput(vp);
133 if (!error)
134 *vpp = vp2;
135 return (error);
136 }
137 if (vp2 == NULL)
138 break;
139
140 }
141 vp->v_hash = hash;
142 LIST_INSERT_HEAD(vfs_hash_index(vp->v_mount, hash), vp, v_hashlist);
143 mtx_unlock(&vfs_hash_mtx);
144 return (0);
145 }
146
147 void
148 vfs_hash_rehash(struct vnode *vp, u_int hash)
149 {
150
151 mtx_lock(&vfs_hash_mtx);
152 LIST_REMOVE(vp, v_hashlist);
153 LIST_INSERT_HEAD(vfs_hash_index(vp->v_mount, hash), vp, v_hashlist);
154 vp->v_hash = hash;
155 mtx_unlock(&vfs_hash_mtx);
156 }
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