pseudofs_vncache.c revision 77998 
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 77998 2001-06-10 18:39:21Z 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, "pfs_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,
89		  struct pfs_node *pn, pid_t pid)
90{
91	struct pfs_vnode *pv;
92	struct pfs_vdata *pvd;
93	int error;
94
95	/* see if the vnode is in the cache */
96	mtx_lock(&pfs_vncache_mutex);
97	for (pv = pfs_vncache; pv; pv = pv->pv_next) {
98		pvd = (struct pfs_vdata *)pv->pv_vnode->v_data;
99		if (pvd->pvd_pn == pn && pvd->pvd_pid == pid) {
100			if (vget(pv->pv_vnode, 0, curproc) == 0) {
101				++pfs_vncache_hits;
102				*vpp = pv->pv_vnode;
103				mtx_unlock(&pfs_vncache_mutex);
104				return (0);
105			}
106			/* XXX if this can happen, we're in trouble */
107			break;
108		}
109	}
110	mtx_unlock(&pfs_vncache_mutex);
111	++pfs_vncache_misses;
112
113	/* nope, get a new one */
114	MALLOC(pv, struct pfs_vnode *, sizeof *pv, M_PFSVNCACHE, M_WAITOK);
115	MALLOC(pvd, struct pfs_vdata *, sizeof *pvd, M_PFSVNCACHE, M_WAITOK);
116	error = getnewvnode(VT_PSEUDOFS, mp, pfs_vnodeop_p, vpp);
117	if (error)
118		return (error);
119	pvd->pvd_pn = pn;
120	pvd->pvd_pid = pid;
121	(*vpp)->v_data = pvd;
122	switch (pn->pn_type) {
123	case pfstype_root:
124		(*vpp)->v_flag = VROOT;
125#if 0
126		printf("root vnode allocated\n");
127#endif
128	case pfstype_dir:
129	case pfstype_this:
130	case pfstype_parent:
131	case pfstype_procdir:
132		(*vpp)->v_type = VDIR;
133		break;
134	case pfstype_file:
135		(*vpp)->v_type = VREG;
136		break;
137	case pfstype_symlink:
138		(*vpp)->v_type = VLNK;
139		break;
140	case pfstype_none:
141		KASSERT(0, ("pfs_vncache_alloc called for null node\n"));
142	default:
143		panic("%s has unexpected type: %d", pn->pn_name, pn->pn_type);
144	}
145	pv->pv_vnode = *vpp;
146	mtx_lock(&pfs_vncache_mutex);
147	pv->pv_next = pfs_vncache;
148	pfs_vncache = pv;
149	mtx_unlock(&pfs_vncache_mutex);
150	return (0);
151}
152
153/*
154 * Free a vnode
155 */
156int
157pfs_vncache_free(struct vnode *vp)
158{
159	struct pfs_vnode *prev, *pv;
160	struct pfs_vdata *pvd;
161
162	mtx_lock(&pfs_vncache_mutex);
163	for (prev = NULL, pv = pfs_vncache; pv; prev = pv, pv = pv->pv_next)
164		if (pv->pv_vnode == vp)
165			break;
166	KASSERT(pv != NULL, ("pfs_vncache_free(): not in cache\n"));
167	if (prev)
168		prev->pv_next = pv->pv_next;
169	else
170		pfs_vncache = pv->pv_next;
171	mtx_unlock(&pfs_vncache_mutex);
172
173	pvd = (struct pfs_vdata *)vp->v_data;
174	FREE(pvd, M_PFSVNCACHE);
175	vp->v_data = NULL;
176	FREE(pv, M_PFSVNCACHE);
177	return (0);
178}
179