pseudofs_vncache.c revision 77965 
1/*-
2 * Copyright (c) 2001 Dag-Erling Co�dan Sm�rgrav
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 *    in this position and unchanged.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. The name of the author may not be used to endorse or promote products
15 *    derived from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 *      $FreeBSD: head/sys/fs/pseudofs/pseudofs_vncache.c 77965 2001-06-10 10:36:16Z des $
29 */
30
31#include <sys/param.h>
32#include <sys/kernel.h>
33#include <sys/systm.h>
34#include <sys/malloc.h>
35#include <sys/mount.h>
36#include <sys/mutex.h>
37#include <sys/sbuf.h>
38#include <sys/sysctl.h>
39#include <sys/vnode.h>
40
41#include <fs/pseudofs/pseudofs.h>
42#include <fs/pseudofs/pseudofs_internal.h>
43
44static MALLOC_DEFINE(M_PFSVNCACHE, "pseudofs_vncache", "pseudofs vnode cache");
45
46static struct mtx pfs_vncache_mutex;
47
48struct pfs_vnode {
49	struct vnode		*pv_vnode;
50	struct pfs_vnode	*pv_next;
51} *pfs_vncache;
52
53SYSCTL_NODE(_vfs_pfs, OID_AUTO, vncache, CTLFLAG_RW, 0,
54    "pseudofs vnode cache");
55
56static int pfs_vncache_hits;
57SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, hits, CTLFLAG_RD, &pfs_vncache_hits, 0,
58    "number of cache hits since initialization");
59
60static int pfs_vncache_misses;
61SYSCTL_INT(_vfs_pfs_vncache, OID_AUTO, misses, CTLFLAG_RD, &pfs_vncache_misses, 0,
62    "number of cache misses since initialization");
63
64extern vop_t **pfs_vnodeop_p;
65
66/*
67 * Initialize vnode cache
68 */
69void
70pfs_vncache_load(void)
71{
72	mtx_init(&pfs_vncache_mutex, "pseudofs_vncache", MTX_DEF);
73}
74
75/*
76 * Tear down vnode cache
77 */
78void
79pfs_vncache_unload(void)
80{
81	mtx_destroy(&pfs_vncache_mutex);
82}
83
84/*
85 * Allocate a vnode
86 */
87int
88pfs_vncache_alloc(struct mount *mp, struct vnode **vpp, struct pfs_node *pn)
89{
90	struct pfs_vnode *pv;
91	int error;
92
93	mtx_lock(&pfs_vncache_mutex);
94
95	/* see if the vnode is in the cache */
96	for (pv = pfs_vncache; pv; pv = pv->pv_next)
97		if (pv->pv_vnode->v_data == pn)
98			if (vget(pv->pv_vnode, 0, curproc) == 0) {
99				++pfs_vncache_hits;
100				*vpp = pv->pv_vnode;
101				mtx_unlock(&pfs_vncache_mutex);
102				return (0);
103			}
104	++pfs_vncache_misses;
105
106	/* nope, get a new one */
107	MALLOC(pv, struct pfs_vnode *, sizeof *pv, M_PFSVNCACHE, M_WAITOK);
108	error = getnewvnode(VT_PSEUDOFS, mp, pfs_vnodeop_p, vpp);
109	if (error) {
110		mtx_unlock(&pfs_vncache_mutex);
111		return (error);
112	}
113	(*vpp)->v_data = pn;
114	switch (pn->pn_type) {
115	case pfstype_root:
116		(*vpp)->v_flag = VROOT;
117#if 0
118		printf("root vnode allocated\n");
119#endif
120	case pfstype_dir:
121	case pfstype_this:
122	case pfstype_parent:
123		(*vpp)->v_type = VDIR;
124		break;
125	case pfstype_file:
126		(*vpp)->v_type = VREG;
127		break;
128	case pfstype_symlink:
129		(*vpp)->v_type = VLNK;
130		break;
131	default:
132		panic("%s has unexpected type: %d", pn->pn_name, pn->pn_type);
133	}
134	pv->pv_vnode = *vpp;
135	pv->pv_next = pfs_vncache;
136	pfs_vncache = pv;
137	mtx_unlock(&pfs_vncache_mutex);
138	return (0);
139}
140
141/*
142 * Free a vnode
143 */
144int
145pfs_vncache_free(struct vnode *vp)
146{
147	struct pfs_vnode *prev, *pv;
148
149	mtx_lock(&pfs_vncache_mutex);
150	for (prev = NULL, pv = pfs_vncache; pv; prev = pv, pv = pv->pv_next)
151		if (pv->pv_vnode == vp)
152			break;
153	if (!pv)
154		printf("pfs_vncache_free(): not in cache\n"); /* it should be! */
155#if 0
156	if (vp->v_data == ((struct pfs_info *)vp->v_mount->mnt_data)->pi_root)
157		printf("root vnode reclaimed\n");
158#endif
159	vp->v_data = NULL;
160	if (pv) {
161		if (prev)
162			prev->pv_next = pv->pv_next;
163		else
164			pfs_vncache = pv->pv_next;
165		FREE(pv, M_PFSVNCACHE);
166	}
167	mtx_unlock(&pfs_vncache_mutex);
168	return (0);
169}
170