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/vnode.h>
37
38static MALLOC_DEFINE(M_VFS_HASH, "vfs_hash", "VFS hash table");
39
40static LIST_HEAD(vfs_hash_head, vnode)	*vfs_hash_tbl;
41static LIST_HEAD(,vnode)		vfs_hash_side;
42static u_long				vfs_hash_mask;
43static struct mtx			vfs_hash_mtx;
44
45static void
46vfs_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 */
55SYSINIT(vfs_hash, SI_SUB_VFS, SI_ORDER_SECOND, vfs_hashinit, NULL);
56
57u_int
58vfs_hash_index(struct vnode *vp)
59{
60
61	return (vp->v_hash + vp->v_mount->mnt_hashseed);
62}
63
64static struct vfs_hash_head *
65vfs_hash_bucket(const struct mount *mp, u_int hash)
66{
67
68	return (&vfs_hash_tbl[(hash + mp->mnt_hashseed) & vfs_hash_mask]);
69}
70
71int
72vfs_hash_get(const struct mount *mp, u_int hash, int flags, struct thread *td, struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg)
73{
74	struct vnode *vp;
75	int error;
76
77	while (1) {
78		mtx_lock(&vfs_hash_mtx);
79		LIST_FOREACH(vp, vfs_hash_bucket(mp, hash), v_hashlist) {
80			if (vp->v_hash != hash)
81				continue;
82			if (vp->v_mount != mp)
83				continue;
84			if (fn != NULL && fn(vp, arg))
85				continue;
86			VI_LOCK(vp);
87			mtx_unlock(&vfs_hash_mtx);
88			error = vget(vp, flags | LK_INTERLOCK, td);
89			if (error == ENOENT && (flags & LK_NOWAIT) == 0)
90				break;
91			if (error)
92				return (error);
93			*vpp = vp;
94			return (0);
95		}
96		if (vp == NULL) {
97			mtx_unlock(&vfs_hash_mtx);
98			*vpp = NULL;
99			return (0);
100		}
101	}
102}
103
104void
105vfs_hash_remove(struct vnode *vp)
106{
107
108	mtx_lock(&vfs_hash_mtx);
109	LIST_REMOVE(vp, v_hashlist);
110	mtx_unlock(&vfs_hash_mtx);
111}
112
113int
114vfs_hash_insert(struct vnode *vp, u_int hash, int flags, struct thread *td, struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg)
115{
116	struct vnode *vp2;
117	int error;
118
119	*vpp = NULL;
120	while (1) {
121		mtx_lock(&vfs_hash_mtx);
122		LIST_FOREACH(vp2,
123		    vfs_hash_bucket(vp->v_mount, hash), v_hashlist) {
124			if (vp2->v_hash != hash)
125				continue;
126			if (vp2->v_mount != vp->v_mount)
127				continue;
128			if (fn != NULL && fn(vp2, arg))
129				continue;
130			VI_LOCK(vp2);
131			mtx_unlock(&vfs_hash_mtx);
132			error = vget(vp2, flags | LK_INTERLOCK, td);
133			if (error == ENOENT && (flags & LK_NOWAIT) == 0)
134				break;
135			mtx_lock(&vfs_hash_mtx);
136			LIST_INSERT_HEAD(&vfs_hash_side, vp, v_hashlist);
137			mtx_unlock(&vfs_hash_mtx);
138			vput(vp);
139			if (!error)
140				*vpp = vp2;
141			return (error);
142		}
143		if (vp2 == NULL)
144			break;
145
146	}
147	vp->v_hash = hash;
148	LIST_INSERT_HEAD(vfs_hash_bucket(vp->v_mount, hash), vp, v_hashlist);
149	mtx_unlock(&vfs_hash_mtx);
150	return (0);
151}
152
153void
154vfs_hash_rehash(struct vnode *vp, u_int hash)
155{
156
157	mtx_lock(&vfs_hash_mtx);
158	LIST_REMOVE(vp, v_hashlist);
159	LIST_INSERT_HEAD(vfs_hash_bucket(vp->v_mount, hash), vp, v_hashlist);
160	vp->v_hash = hash;
161	mtx_unlock(&vfs_hash_mtx);
162}
163