[apple/xnu.git] / bsd / miscfs / nullfs / null_subr.c

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 * 
 * This Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
/*
 * Copyright (c) 1992, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software donated to Berkeley by
 * Jan-Simon Pendry.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)null_subr.c	8.7 (Berkeley) 5/14/95
 *
 *	null_subr.c	8.4 (Berkeley) 1/21/94
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/malloc.h>
#include <sys/ubc.h>
#include <miscfs/nullfs/null.h>

#define LOG2_SIZEVNODE 7		/* log2(sizeof struct vnode) */
#define	NNULLNODECACHE 16

/*
 * Null layer cache:
 * Each cache entry holds a reference to the lower vnode
 * along with a pointer to the alias vnode.  When an
 * entry is added the lower vnode is VREF'd.  When the
 * alias is removed the lower vnode is vrele'd.
 */

#define	NULL_NHASH(vp) \
	(&null_node_hashtbl[(((u_long)vp)>>LOG2_SIZEVNODE) & null_node_hash])
LIST_HEAD(null_node_hashhead, null_node) *null_node_hashtbl;
u_long null_node_hash;

/*
 * Initialise cache headers
 */
nullfs_init()
{

#ifdef NULLFS_DIAGNOSTIC
	printf("nullfs_init\n");		/* printed during system boot */
#endif
	null_node_hashtbl = hashinit(NNULLNODECACHE, M_CACHE, &null_node_hash);
}

/*
 * Return a VREF'ed alias for lower vnode if already exists, else 0.
 */
static struct vnode *
null_node_find(mp, lowervp)
	struct mount *mp;
	struct vnode *lowervp;
{
	struct proc *p = curproc;	/* XXX */
	struct null_node_hashhead *hd;
	struct null_node *a;
	struct vnode *vp;

	/*
	 * Find hash base, and then search the (two-way) linked
	 * list looking for a null_node structure which is referencing
	 * the lower vnode.  If found, the increment the null_node
	 * reference count (but NOT the lower vnode's VREF counter).
	 */
	hd = NULL_NHASH(lowervp);
loop:
	for (a = hd->lh_first; a != 0; a = a->null_hash.le_next) {
		if (a->null_lowervp == lowervp && NULLTOV(a)->v_mount == mp) {
			vp = NULLTOV(a);
			/*
			 * We need vget for the VXLOCK
			 * stuff, but we don't want to lock
			 * the lower node.
			 */
			if (vget(vp, 0, p)) {
				printf ("null_node_find: vget failed.\n");
				goto loop;
			};
			return (vp);
		}
	}

	return NULL;
}


/*
 * Make a new null_node node.
 * Vp is the alias vnode, lofsvp is the lower vnode.
 * Maintain a reference to (lowervp).
 */
static int
null_node_alloc(mp, lowervp, vpp)
	struct mount *mp;
	struct vnode *lowervp;
	struct vnode **vpp;
{
	struct null_node_hashhead *hd;
	struct null_node *xp;
	struct vnode *othervp, *vp;
	int error;

	MALLOC(xp, struct null_node *, sizeof(struct null_node), M_TEMP, M_WAITOK);
	if (error = getnewvnode(VT_NULL, mp, null_vnodeop_p, vpp)) {
		FREE(xp, M_TEMP);
		return (error);
	}
	vp = *vpp;

	vp->v_type = lowervp->v_type;
	xp->null_vnode = vp;
	vp->v_data = xp;
	xp->null_lowervp = lowervp;
	/*
	 * Before we insert our new node onto the hash chains,
	 * check to see if someone else has beaten us to it.
	 */
	if (othervp = null_node_find(lowervp)) {
		FREE(xp, M_TEMP);
		vp->v_type = VBAD;	/* node is discarded */
		vp->v_usecount = 0;	/* XXX */
		vp->v_data = 0; /* prevent access to freed data */
		*vpp = othervp;
		return 0;
	};
	if (vp->v_type == VREG)
		ubc_info_init(vp);
	VREF(lowervp);   /* Extra VREF will be vrele'd in null_node_create */
	hd = NULL_NHASH(lowervp);
	LIST_INSERT_HEAD(hd, xp, null_hash);
	return 0;
}


/*
 * Try to find an existing null_node vnode refering
 * to it, otherwise make a new null_node vnode which
 * contains a reference to the lower vnode.
 */
int
null_node_create(mp, lowervp, newvpp)
	struct mount *mp;
	struct vnode *lowervp;
	struct vnode **newvpp;
{
	struct vnode *aliasvp;

	if (aliasvp = null_node_find(mp, lowervp)) {
		/*
		 * null_node_find has taken another reference
		 * to the alias vnode.
		 */
#ifdef NULLFS_DIAGNOSTIC
		vprint("null_node_create: exists", NULLTOV(ap));
#endif
		/* VREF(aliasvp); --- done in null_node_find */
	} else {
		int error;

		/*
		 * Get new vnode.
		 */
#ifdef NULLFS_DIAGNOSTIC
		printf("null_node_create: create new alias vnode\n");
#endif

		/*
		 * Make new vnode reference the null_node.
		 */
		if (error = null_node_alloc(mp, lowervp, &aliasvp))
			return error;

		/*
		 * aliasvp is already VREF'd by getnewvnode()
		 */
	}

	vrele(lowervp);

#if DIAGNOSTIC
	if (lowervp->v_usecount < 1) {
		/* Should never happen... */
		vprint ("null_node_create: alias ", aliasvp);
		vprint ("null_node_create: lower ", lowervp);
		panic ("null_node_create: lower has 0 usecount.");
	};
#endif

#ifdef NULLFS_DIAGNOSTIC
	vprint("null_node_create: alias", aliasvp);
	vprint("null_node_create: lower", lowervp);
#endif

	*newvpp = aliasvp;
	return (0);
}
#ifdef NULLFS_DIAGNOSTIC
struct vnode *
null_checkvp(vp, fil, lno)
	struct vnode *vp;
	char *fil;
	int lno;
{
	struct null_node *a = VTONULL(vp);
#ifdef notyet
	/*
	 * Can't do this check because vop_reclaim runs
	 * with a funny vop vector.
	 */
	if (vp->v_op != null_vnodeop_p) {
		printf ("null_checkvp: on non-null-node\n");
		while (null_checkvp_barrier) /*WAIT*/ ;
		panic("null_checkvp");
	};
#endif
	if (a->null_lowervp == NULL) {
		/* Should never happen */
		int i; u_long *p;
		printf("vp = %x, ZERO ptr\n", vp);
		for (p = (u_long *) a, i = 0; i < 8; i++)
			printf(" %x", p[i]);
		printf("\n");
		/* wait for debugger */
		while (null_checkvp_barrier) /*WAIT*/ ;
		panic("null_checkvp");
	}
	if (a->null_lowervp->v_usecount < 1) {
		int i; u_long *p;
		printf("vp = %x, unref'ed lowervp\n", vp);
		for (p = (u_long *) a, i = 0; i < 8; i++)
			printf(" %x", p[i]);
		printf("\n");
		/* wait for debugger */
		while (null_checkvp_barrier) /*WAIT*/ ;
		panic ("null with unref'ed lowervp");
	};
#ifdef notyet
	printf("null %x/%d -> %x/%d [%s, %d]\n",
	        NULLTOV(a), NULLTOV(a)->v_usecount,
		a->null_lowervp, a->null_lowervp->v_usecount,
		fil, lno);
#endif
	return a->null_lowervp;
}
#endif
Commit	Line	Data
1c79356b A	1	/*
	2	* Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
	3	*
	4	* @APPLE_LICENSE_HEADER_START@
	5	*
	6	* The contents of this file constitute Original Code as defined in and
	7	* are subject to the Apple Public Source License Version 1.1 (the
	8	* "License"). You may not use this file except in compliance with the
	9	* License. Please obtain a copy of the License at
	10	* http://www.apple.com/publicsource and read it before using this file.
	11	*
	12	* This Original Code and all software distributed under the License are
	13	* distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
	14	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
	15	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
	16	* FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
	17	* License for the specific language governing rights and limitations
	18	* under the License.
	19	*
	20	* @APPLE_LICENSE_HEADER_END@
	21	*/
	22	/* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
	23	/*
	24	* Copyright (c) 1992, 1993
	25	* The Regents of the University of California. All rights reserved.
	26	*
	27	* This code is derived from software donated to Berkeley by
	28	* Jan-Simon Pendry.
	29	*
	30	* Redistribution and use in source and binary forms, with or without
	31	* modification, are permitted provided that the following conditions
	32	* are met:
	33	* 1. Redistributions of source code must retain the above copyright
	34	* notice, this list of conditions and the following disclaimer.
	35	* 2. Redistributions in binary form must reproduce the above copyright
	36	* notice, this list of conditions and the following disclaimer in the
	37	* documentation and/or other materials provided with the distribution.
	38	* 3. All advertising materials mentioning features or use of this software
	39	* must display the following acknowledgement:
	40	* This product includes software developed by the University of
	41	* California, Berkeley and its contributors.
	42	* 4. Neither the name of the University nor the names of its contributors
	43	* may be used to endorse or promote products derived from this software
	44	* without specific prior written permission.
	45	*
	46	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	47	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	48	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	49	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	50	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	51	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	52	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	53	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	54	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	55	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	56	* SUCH DAMAGE.
	57	*
	58	* @(#)null_subr.c 8.7 (Berkeley) 5/14/95
	59	*
	60	* null_subr.c 8.4 (Berkeley) 1/21/94
	61	*/
	62
	63	#include <sys/param.h>
	64	#include <sys/systm.h>
65	#include <sys/proc.h>
66	#include <sys/time.h>
67	#include <sys/types.h>
68	#include <sys/vnode.h>
69	#include <sys/mount.h>
70	#include <sys/namei.h>
71	#include <sys/malloc.h>
72	#include <sys/ubc.h>
73	#include <miscfs/nullfs/null.h>
74
75	#define LOG2_SIZEVNODE 7 /* log2(sizeof struct vnode) */
76	#define NNULLNODECACHE 16
77
78	/*
79	* Null layer cache:
80	* Each cache entry holds a reference to the lower vnode
81	* along with a pointer to the alias vnode. When an
82	* entry is added the lower vnode is VREF'd. When the
83	* alias is removed the lower vnode is vrele'd.
84	*/
85
86	#define NULL_NHASH(vp) \
87	(&null_node_hashtbl[(((u_long)vp)>>LOG2_SIZEVNODE) & null_node_hash])
88	LIST_HEAD(null_node_hashhead, null_node) *null_node_hashtbl;
89	u_long null_node_hash;
90
91	/*
92	* Initialise cache headers
93	*/
94	nullfs_init()
95	{
96
97	#ifdef NULLFS_DIAGNOSTIC
98	printf("nullfs_init\n"); /* printed during system boot */
99	#endif
100	null_node_hashtbl = hashinit(NNULLNODECACHE, M_CACHE, &null_node_hash);
101	}
102
103	/*
104	* Return a VREF'ed alias for lower vnode if already exists, else 0.
105	*/
106	static struct vnode *
107	null_node_find(mp, lowervp)
108	struct mount *mp;
109	struct vnode *lowervp;
110	{
111	struct proc p = curproc; / XXX */
112	struct null_node_hashhead *hd;
113	struct null_node *a;
114	struct vnode *vp;
115
116	/*
117	* Find hash base, and then search the (two-way) linked
118	* list looking for a null_node structure which is referencing
119	* the lower vnode. If found, the increment the null_node
120	* reference count (but NOT the lower vnode's VREF counter).
121	*/
122	hd = NULL_NHASH(lowervp);
123	loop:
124	for (a = hd->lh_first; a != 0; a = a->null_hash.le_next) {
125	if (a->null_lowervp == lowervp && NULLTOV(a)->v_mount == mp) {
126	vp = NULLTOV(a);
127	/*
128	* We need vget for the VXLOCK
129	* stuff, but we don't want to lock
130	* the lower node.
131	*/
132	if (vget(vp, 0, p)) {
133	printf ("null_node_find: vget failed.\n");
134	goto loop;
135	};
136	return (vp);
137	}
138	}
139
140	return NULL;
141	}
142
143
144	/*
145	* Make a new null_node node.
146	* Vp is the alias vnode, lofsvp is the lower vnode.
147	* Maintain a reference to (lowervp).
148	*/
149	static int
150	null_node_alloc(mp, lowervp, vpp)
151	struct mount *mp;
152	struct vnode *lowervp;
153	struct vnode **vpp;
154	{
155	struct null_node_hashhead *hd;
156	struct null_node *xp;
157	struct vnode othervp, vp;
158	int error;
159
160	MALLOC(xp, struct null_node *, sizeof(struct null_node), M_TEMP, M_WAITOK);
161	if (error = getnewvnode(VT_NULL, mp, null_vnodeop_p, vpp)) {
162	FREE(xp, M_TEMP);
163	return (error);
164	}
165	vp = *vpp;
166
167	vp->v_type = lowervp->v_type;
168	xp->null_vnode = vp;
169	vp->v_data = xp;
170	xp->null_lowervp = lowervp;
171	/*
172	* Before we insert our new node onto the hash chains,
173	* check to see if someone else has beaten us to it.
174	*/
175	if (othervp = null_node_find(lowervp)) {
176	FREE(xp, M_TEMP);
177	vp->v_type = VBAD; /* node is discarded */
178	vp->v_usecount = 0; /* XXX */
179	vp->v_data = 0; /* prevent access to freed data */
180	*vpp = othervp;
181	return 0;
182	};
183	if (vp->v_type == VREG)
184	ubc_info_init(vp);
185	VREF(lowervp); /* Extra VREF will be vrele'd in null_node_create */
186	hd = NULL_NHASH(lowervp);
187	LIST_INSERT_HEAD(hd, xp, null_hash);
188	return 0;
189	}
190
191
192	/*
193	* Try to find an existing null_node vnode refering
194	* to it, otherwise make a new null_node vnode which
195	* contains a reference to the lower vnode.
196	*/
197	int
198	null_node_create(mp, lowervp, newvpp)
199	struct mount *mp;
200	struct vnode *lowervp;
201	struct vnode **newvpp;
202	{
203	struct vnode *aliasvp;
204
205	if (aliasvp = null_node_find(mp, lowervp)) {
206	/*
207	* null_node_find has taken another reference
208	* to the alias vnode.
209	*/
210	#ifdef NULLFS_DIAGNOSTIC
211	vprint("null_node_create: exists", NULLTOV(ap));
212	#endif
213	/* VREF(aliasvp); --- done in null_node_find */
214	} else {
215	int error;
216
217	/*
218	* Get new vnode.
219	*/
220	#ifdef NULLFS_DIAGNOSTIC
221	printf("null_node_create: create new alias vnode\n");
222	#endif
223
224	/*
225	* Make new vnode reference the null_node.
226	*/
227	if (error = null_node_alloc(mp, lowervp, &aliasvp))
228	return error;
229
230	/*
231	* aliasvp is already VREF'd by getnewvnode()
232	*/
233	}
234
235	vrele(lowervp);
236
237	#if DIAGNOSTIC
238	if (lowervp->v_usecount < 1) {
239	/* Should never happen... */
240	vprint ("null_node_create: alias ", aliasvp);
241	vprint ("null_node_create: lower ", lowervp);
242	panic ("null_node_create: lower has 0 usecount.");
243	};
244	#endif
245
246	#ifdef NULLFS_DIAGNOSTIC
247	vprint("null_node_create: alias", aliasvp);
248	vprint("null_node_create: lower", lowervp);
249	#endif
250
251	*newvpp = aliasvp;
252	return (0);
253	}
254	#ifdef NULLFS_DIAGNOSTIC
255	struct vnode *
256	null_checkvp(vp, fil, lno)
257	struct vnode *vp;
258	char *fil;
259	int lno;
260	{
261	struct null_node *a = VTONULL(vp);
262	#ifdef notyet
263	/*
264	* Can't do this check because vop_reclaim runs
265	* with a funny vop vector.
266	*/
267	if (vp->v_op != null_vnodeop_p) {
268	printf ("null_checkvp: on non-null-node\n");
269	while (null_checkvp_barrier) /WAIT/ ;
270	panic("null_checkvp");
271	};
272	#endif
273	if (a->null_lowervp == NULL) {
274	/* Should never happen */
275	int i; u_long *p;
276	printf("vp = %x, ZERO ptr\n", vp);
277	for (p = (u_long *) a, i = 0; i < 8; i++)
278	printf(" %x", p[i]);
279	printf("\n");
280	/* wait for debugger */
281	while (null_checkvp_barrier) /WAIT/ ;
282	panic("null_checkvp");
283	}
284	if (a->null_lowervp->v_usecount < 1) {
285	int i; u_long *p;
286	printf("vp = %x, unref'ed lowervp\n", vp);
287	for (p = (u_long *) a, i = 0; i < 8; i++)
288	printf(" %x", p[i]);
289	printf("\n");
290	/* wait for debugger */
291	while (null_checkvp_barrier) /WAIT/ ;
292	panic ("null with unref'ed lowervp");
293	};
294	#ifdef notyet
295	printf("null %x/%d -> %x/%d [%s, %d]\n",
296	NULLTOV(a), NULLTOV(a)->v_usecount,
297	a->null_lowervp, a->null_lowervp->v_usecount,
298	fil, lno);
299	#endif
300	return a->null_lowervp;
301	}
302	#endif