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,
73    struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg)
74{
75	struct vnode *vp;
76	int error;
77
78	while (1) {
79		mtx_lock(&vfs_hash_mtx);
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			VI_LOCK(vp);
88			mtx_unlock(&vfs_hash_mtx);
89			error = vget(vp, flags | LK_INTERLOCK, 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			mtx_unlock(&vfs_hash_mtx);
99			*vpp = NULL;
100			return (0);
101		}
102	}
103}
104
105void
106vfs_hash_ref(const struct mount *mp, u_int hash, struct thread *td,
107    struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg)
108{
109	struct vnode *vp;
110
111	while (1) {
112		mtx_lock(&vfs_hash_mtx);
113		LIST_FOREACH(vp, vfs_hash_bucket(mp, hash), v_hashlist) {
114			if (vp->v_hash != hash)
115				continue;
116			if (vp->v_mount != mp)
117				continue;
118			if (fn != NULL && fn(vp, arg))
119				continue;
120			vhold(vp);
121			mtx_unlock(&vfs_hash_mtx);
122			vref(vp);
123			vdrop(vp);
124			*vpp = vp;
125			return;
126		}
127		if (vp == NULL) {
128			mtx_unlock(&vfs_hash_mtx);
129			*vpp = NULL;
130			return;
131		}
132	}
133}
134
135void
136vfs_hash_remove(struct vnode *vp)
137{
138
139	mtx_lock(&vfs_hash_mtx);
140	LIST_REMOVE(vp, v_hashlist);
141	mtx_unlock(&vfs_hash_mtx);
142}
143
144int
145vfs_hash_insert(struct vnode *vp, u_int hash, int flags, struct thread *td,
146    struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg)
147{
148	struct vnode *vp2;
149	int error;
150
151	*vpp = NULL;
152	while (1) {
153		mtx_lock(&vfs_hash_mtx);
154		LIST_FOREACH(vp2,
155		    vfs_hash_bucket(vp->v_mount, hash), v_hashlist) {
156			if (vp2->v_hash != hash)
157				continue;
158			if (vp2->v_mount != vp->v_mount)
159				continue;
160			if (fn != NULL && fn(vp2, arg))
161				continue;
162			VI_LOCK(vp2);
163			mtx_unlock(&vfs_hash_mtx);
164			error = vget(vp2, flags | LK_INTERLOCK, td);
165			if (error == ENOENT && (flags & LK_NOWAIT) == 0)
166				break;
167			mtx_lock(&vfs_hash_mtx);
168			LIST_INSERT_HEAD(&vfs_hash_side, vp, v_hashlist);
169			mtx_unlock(&vfs_hash_mtx);
170			vput(vp);
171			if (!error)
172				*vpp = vp2;
173			return (error);
174		}
175		if (vp2 == NULL)
176			break;
177
178	}
179	vp->v_hash = hash;
180	LIST_INSERT_HEAD(vfs_hash_bucket(vp->v_mount, hash), vp, v_hashlist);
181	mtx_unlock(&vfs_hash_mtx);
182	return (0);
183}
184
185void
186vfs_hash_rehash(struct vnode *vp, u_int hash)
187{
188
189	mtx_lock(&vfs_hash_mtx);
190	LIST_REMOVE(vp, v_hashlist);
191	LIST_INSERT_HEAD(vfs_hash_bucket(vp->v_mount, hash), vp, v_hashlist);
192	vp->v_hash = hash;
193	mtx_unlock(&vfs_hash_mtx);
194}
195
196void
197vfs_hash_changesize(int newmaxvnodes)
198{
199	struct vfs_hash_head *vfs_hash_newtbl, *vfs_hash_oldtbl;
200	u_long vfs_hash_newmask, vfs_hash_oldmask;
201	struct vnode *vp;
202	int i;
203
204	vfs_hash_newtbl = hashinit(newmaxvnodes, M_VFS_HASH,
205		&vfs_hash_newmask);
206	/* If same hash table size, nothing to do */
207	if (vfs_hash_mask == vfs_hash_newmask) {
208		free(vfs_hash_newtbl, M_VFS_HASH);
209		return;
210	}
211	/*
212	 * Move everything from the old hash table to the new table.
213	 * None of the vnodes in the table can be recycled because to
214	 * do so, they have to be removed from the hash table.
215	 */
216	mtx_lock(&vfs_hash_mtx);
217	vfs_hash_oldtbl = vfs_hash_tbl;
218	vfs_hash_oldmask = vfs_hash_mask;
219	vfs_hash_tbl = vfs_hash_newtbl;
220	vfs_hash_mask = vfs_hash_newmask;
221	for (i = 0; i <= vfs_hash_oldmask; i++) {
222		while ((vp = LIST_FIRST(&vfs_hash_oldtbl[i])) != NULL) {
223			LIST_REMOVE(vp, v_hashlist);
224			LIST_INSERT_HEAD(
225			    vfs_hash_bucket(vp->v_mount, vp->v_hash),
226			    vp, v_hashlist);
227		}
228	}
229	mtx_unlock(&vfs_hash_mtx);
230	free(vfs_hash_oldtbl, M_VFS_HASH);
231}
232