null_vfsops.c revision 65467
1/*
2 * Copyright (c) 1992, 1993, 1995
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software donated to Berkeley by
6 * Jan-Simon Pendry.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 *    must display the following acknowledgement:
18 *	This product includes software developed by the University of
19 *	California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 *    may be used to endorse or promote products derived from this software
22 *    without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 *
36 *	@(#)null_vfsops.c	8.2 (Berkeley) 1/21/94
37 *
38 * @(#)lofs_vfsops.c	1.2 (Berkeley) 6/18/92
39 * $FreeBSD: head/sys/fs/nullfs/null_vfsops.c 65467 2000-09-05 09:02:07Z bp $
40 */
41
42/*
43 * Null Layer
44 * (See null_vnops.c for a description of what this does.)
45 */
46
47#include <sys/param.h>
48#include <sys/systm.h>
49#include <sys/kernel.h>
50#include <sys/proc.h>
51#include <sys/malloc.h>
52#include <sys/vnode.h>
53#include <sys/mount.h>
54#include <sys/namei.h>
55#include <miscfs/nullfs/null.h>
56
57static MALLOC_DEFINE(M_NULLFSMNT, "NULLFS mount", "NULLFS mount structure");
58
59static int	nullfs_fhtovp(struct mount *mp, struct fid *fidp,
60				   struct vnode **vpp);
61static int	nullfs_checkexp(struct mount *mp, struct sockaddr *nam,
62				    int *extflagsp, struct ucred **credanonp);
63static int	nullfs_mount(struct mount *mp, char *path, caddr_t data,
64				  struct nameidata *ndp, struct proc *p);
65static int	nullfs_quotactl(struct mount *mp, int cmd, uid_t uid,
66				     caddr_t arg, struct proc *p);
67static int	nullfs_root(struct mount *mp, struct vnode **vpp);
68static int	nullfs_start(struct mount *mp, int flags, struct proc *p);
69static int	nullfs_statfs(struct mount *mp, struct statfs *sbp,
70				   struct proc *p);
71static int	nullfs_sync(struct mount *mp, int waitfor,
72				 struct ucred *cred, struct proc *p);
73static int	nullfs_unmount(struct mount *mp, int mntflags, struct proc *p);
74static int	nullfs_vget(struct mount *mp, ino_t ino, struct vnode **vpp);
75static int	nullfs_vptofh(struct vnode *vp, struct fid *fhp);
76
77/*
78 * Mount null layer
79 */
80static int
81nullfs_mount(mp, path, data, ndp, p)
82	struct mount *mp;
83	char *path;
84	caddr_t data;
85	struct nameidata *ndp;
86	struct proc *p;
87{
88	int error = 0;
89	struct null_args args;
90	struct vnode *lowerrootvp, *vp;
91	struct vnode *nullm_rootvp;
92	struct null_mount *xmp;
93	u_int size;
94	int isvnunlocked = 0;
95
96	NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp);
97
98	/*
99	 * Update is a no-op
100	 */
101	if (mp->mnt_flag & MNT_UPDATE) {
102		return (EOPNOTSUPP);
103		/* return VFS_MOUNT(MOUNTTONULLMOUNT(mp)->nullm_vfs, path, data, ndp, p);*/
104	}
105
106	/*
107	 * Get argument
108	 */
109	error = copyin(data, (caddr_t)&args, sizeof(struct null_args));
110	if (error)
111		return (error);
112
113	/*
114	 * Unlock lower node to avoid deadlock.
115	 * (XXX) VOP_ISLOCKED is needed?
116	 */
117	if ((mp->mnt_vnodecovered->v_op == null_vnodeop_p) &&
118		VOP_ISLOCKED(mp->mnt_vnodecovered, NULL)) {
119		VOP_UNLOCK(mp->mnt_vnodecovered, 0, p);
120		isvnunlocked = 1;
121	}
122	/*
123	 * Find lower node
124	 */
125	NDINIT(ndp, LOOKUP, FOLLOW|WANTPARENT|LOCKLEAF,
126		UIO_USERSPACE, args.target, p);
127	error = namei(ndp);
128	/*
129	 * Re-lock vnode.
130	 */
131	if (isvnunlocked && !VOP_ISLOCKED(mp->mnt_vnodecovered, NULL))
132		vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY, p);
133
134	if (error)
135		return (error);
136	NDFREE(ndp, NDF_ONLY_PNBUF);
137
138	/*
139	 * Sanity check on lower vnode
140	 */
141	lowerrootvp = ndp->ni_vp;
142
143	vrele(ndp->ni_dvp);
144	ndp->ni_dvp = NULLVP;
145
146	/*
147	 * Check multi null mount to avoid `lock against myself' panic.
148	 */
149	if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) {
150		NULLFSDEBUG("nullfs_mount: multi null mount?\n");
151		return (EDEADLK);
152	}
153
154	xmp = (struct null_mount *) malloc(sizeof(struct null_mount),
155				M_NULLFSMNT, M_WAITOK);	/* XXX */
156
157	/*
158	 * Save reference to underlying FS
159	 */
160	xmp->nullm_vfs = lowerrootvp->v_mount;
161
162	/*
163	 * Save reference.  Each mount also holds
164	 * a reference on the root vnode.
165	 */
166	error = null_node_create(mp, lowerrootvp, &vp);
167	/*
168	 * Unlock the node (either the lower or the alias)
169	 */
170	VOP_UNLOCK(vp, 0, p);
171	/*
172	 * Make sure the node alias worked
173	 */
174	if (error) {
175		vrele(lowerrootvp);
176		free(xmp, M_NULLFSMNT);	/* XXX */
177		return (error);
178	}
179
180	/*
181	 * Keep a held reference to the root vnode.
182	 * It is vrele'd in nullfs_unmount.
183	 */
184	nullm_rootvp = vp;
185	nullm_rootvp->v_flag |= VROOT;
186	xmp->nullm_rootvp = nullm_rootvp;
187	if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL)
188		mp->mnt_flag |= MNT_LOCAL;
189	mp->mnt_data = (qaddr_t) xmp;
190	vfs_getnewfsid(mp);
191
192	(void) copyinstr(path, mp->mnt_stat.f_mntonname, MNAMELEN - 1, &size);
193	bzero(mp->mnt_stat.f_mntonname + size, MNAMELEN - size);
194	(void) copyinstr(args.target, mp->mnt_stat.f_mntfromname, MNAMELEN - 1,
195	    &size);
196	bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size);
197	(void)nullfs_statfs(mp, &mp->mnt_stat, p);
198	NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n",
199		mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
200	return (0);
201}
202
203/*
204 * VFS start.  Nothing needed here - the start routine
205 * on the underlying filesystem will have been called
206 * when that filesystem was mounted.
207 */
208static int
209nullfs_start(mp, flags, p)
210	struct mount *mp;
211	int flags;
212	struct proc *p;
213{
214	return (0);
215	/* return VFS_START(MOUNTTONULLMOUNT(mp)->nullm_vfs, flags, p); */
216}
217
218/*
219 * Free reference to null layer
220 */
221static int
222nullfs_unmount(mp, mntflags, p)
223	struct mount *mp;
224	int mntflags;
225	struct proc *p;
226{
227	struct vnode *nullm_rootvp = MOUNTTONULLMOUNT(mp)->nullm_rootvp;
228	void *mntdata;
229	int error;
230	int flags = 0;
231
232	NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp);
233
234	if (mntflags & MNT_FORCE)
235		flags |= FORCECLOSE;
236
237	/*
238	 * Clear out buffer cache.  I don't think we
239	 * ever get anything cached at this level at the
240	 * moment, but who knows...
241	 */
242#if 0
243	mntflushbuf(mp, 0);
244	if (mntinvalbuf(mp, 1))
245		return (EBUSY);
246#endif
247	if (nullm_rootvp->v_usecount > 1)
248		return (EBUSY);
249	error = vflush(mp, nullm_rootvp, flags);
250	if (error)
251		return (error);
252
253#ifdef NULLFS_DEBUG
254	vprint("alias root of lower", nullm_rootvp);
255#endif
256	/*
257	 * Release reference on underlying root vnode
258	 */
259	vrele(nullm_rootvp);
260	/*
261	 * And blow it away for future re-use
262	 */
263	vgone(nullm_rootvp);
264	/*
265	 * Finally, throw away the null_mount structure
266	 */
267	mntdata = mp->mnt_data;
268	mp->mnt_data = 0;
269	free(mntdata, M_NULLFSMNT);	/* XXX */
270	return 0;
271}
272
273static int
274nullfs_root(mp, vpp)
275	struct mount *mp;
276	struct vnode **vpp;
277{
278	struct proc *p = curproc;	/* XXX */
279	struct vnode *vp;
280
281	NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp,
282	    (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp,
283	    (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp));
284
285	/*
286	 * Return locked reference to root.
287	 */
288	vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp;
289	VREF(vp);
290#ifdef NULLFS_DEBUG
291	if (VOP_ISLOCKED(vp, NULL)) {
292		/*
293		 * XXX
294		 * Should we check type of node?
295		 */
296		printf("nullfs_root: multi null mount?\n");
297		vrele(vp);
298		return (EDEADLK);
299	}
300#endif
301	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p);
302	*vpp = vp;
303	return 0;
304}
305
306static int
307nullfs_quotactl(mp, cmd, uid, arg, p)
308	struct mount *mp;
309	int cmd;
310	uid_t uid;
311	caddr_t arg;
312	struct proc *p;
313{
314	return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, p);
315}
316
317static int
318nullfs_statfs(mp, sbp, p)
319	struct mount *mp;
320	struct statfs *sbp;
321	struct proc *p;
322{
323	int error;
324	struct statfs mstat;
325
326	NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp,
327	    (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp,
328	    (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp));
329
330	bzero(&mstat, sizeof(mstat));
331
332	error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, p);
333	if (error)
334		return (error);
335
336	/* now copy across the "interesting" information and fake the rest */
337	sbp->f_type = mstat.f_type;
338	sbp->f_flags = mstat.f_flags;
339	sbp->f_bsize = mstat.f_bsize;
340	sbp->f_iosize = mstat.f_iosize;
341	sbp->f_blocks = mstat.f_blocks;
342	sbp->f_bfree = mstat.f_bfree;
343	sbp->f_bavail = mstat.f_bavail;
344	sbp->f_files = mstat.f_files;
345	sbp->f_ffree = mstat.f_ffree;
346	if (sbp != &mp->mnt_stat) {
347		bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid));
348		bcopy(mp->mnt_stat.f_mntonname, sbp->f_mntonname, MNAMELEN);
349		bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN);
350	}
351	return (0);
352}
353
354static int
355nullfs_sync(mp, waitfor, cred, p)
356	struct mount *mp;
357	int waitfor;
358	struct ucred *cred;
359	struct proc *p;
360{
361	/*
362	 * XXX - Assumes no data cached at null layer.
363	 */
364	return (0);
365}
366
367static int
368nullfs_vget(mp, ino, vpp)
369	struct mount *mp;
370	ino_t ino;
371	struct vnode **vpp;
372{
373
374	return VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, vpp);
375}
376
377static int
378nullfs_fhtovp(mp, fidp, vpp)
379	struct mount *mp;
380	struct fid *fidp;
381	struct vnode **vpp;
382{
383
384	return VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, vpp);
385}
386
387static int
388nullfs_checkexp(mp, nam, extflagsp, credanonp)
389	struct mount *mp;
390	struct sockaddr *nam;
391	int *extflagsp;
392	struct ucred **credanonp;
393{
394
395	return VFS_CHECKEXP(MOUNTTONULLMOUNT(mp)->nullm_vfs, nam,
396		extflagsp, credanonp);
397}
398
399static int
400nullfs_vptofh(vp, fhp)
401	struct vnode *vp;
402	struct fid *fhp;
403{
404	return VFS_VPTOFH(NULLVPTOLOWERVP(vp), fhp);
405}
406
407static int
408nullfs_extattrctl(mp, cmd, attrname, arg, p)
409	struct mount *mp;
410	int cmd;
411	const char *attrname;
412	caddr_t arg;
413	struct proc *p;
414{
415	return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, attrname,
416	    arg, p);
417}
418
419
420static struct vfsops null_vfsops = {
421	nullfs_mount,
422	nullfs_start,
423	nullfs_unmount,
424	nullfs_root,
425	nullfs_quotactl,
426	nullfs_statfs,
427	nullfs_sync,
428	nullfs_vget,
429	nullfs_fhtovp,
430	nullfs_checkexp,
431	nullfs_vptofh,
432	nullfs_init,
433	nullfs_uninit,
434	nullfs_extattrctl,
435};
436
437VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK);
438