null_vfsops.c revision 97186
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 97186 2002-05-23 23:07:27Z mux $
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/lock.h>
51#include <sys/malloc.h>
52#include <sys/mount.h>
53#include <sys/namei.h>
54#include <sys/proc.h>
55#include <sys/vnode.h>
56
57#include <fs/nullfs/null.h>
58
59static MALLOC_DEFINE(M_NULLFSMNT, "NULLFS mount", "NULLFS mount structure");
60
61static int	nullfs_fhtovp(struct mount *mp, struct fid *fidp,
62				   struct vnode **vpp);
63static int	nullfs_checkexp(struct mount *mp, struct sockaddr *nam,
64				    int *extflagsp, struct ucred **credanonp);
65static int	nullfs_mount(struct mount *mp, struct nameidata *ndp,
66				   struct thread *td);
67static int	nullfs_quotactl(struct mount *mp, int cmd, uid_t uid,
68				     caddr_t arg, struct thread *td);
69static int	nullfs_root(struct mount *mp, struct vnode **vpp);
70static int	nullfs_start(struct mount *mp, int flags, struct thread *td);
71static int	nullfs_statfs(struct mount *mp, struct statfs *sbp,
72				   struct thread *td);
73static int	nullfs_sync(struct mount *mp, int waitfor,
74				 struct ucred *cred, struct thread *td);
75static int	nullfs_unmount(struct mount *mp, int mntflags, struct thread *td);
76static int	nullfs_vget(struct mount *mp, ino_t ino, int flags,
77				 struct vnode **vpp);
78static int	nullfs_vptofh(struct vnode *vp, struct fid *fhp);
79static int	nullfs_extattrctl(struct mount *mp, int cmd,
80				       struct vnode *filename_vp,
81				       int namespace, const char *attrname,
82				       struct thread *td);
83
84/*
85 * Mount null layer
86 */
87static int
88nullfs_mount(mp, ndp, td)
89	struct mount *mp;
90	struct nameidata *ndp;
91	struct thread *td;
92{
93	int error = 0;
94	struct vnode *lowerrootvp, *vp;
95	struct vnode *nullm_rootvp;
96	struct null_mount *xmp;
97	char *target;
98	size_t size;
99	int isvnunlocked = 0, len;
100
101	NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp);
102
103	/*
104	 * Update is a no-op
105	 */
106	if (mp->mnt_flag & MNT_UPDATE) {
107		return (EOPNOTSUPP);
108		/* return VFS_MOUNT(MOUNTTONULLMOUNT(mp)->nullm_vfs, path, data, ndp, td);*/
109	}
110
111	/*
112	 * Get argument
113	 */
114	error = vfs_getopt(mp->mnt_optnew, "target", (void **)&target, &len);
115	if (error || target[len - 1] != '\0')
116		return (EINVAL);
117
118	/*
119	 * Unlock lower node to avoid deadlock.
120	 * (XXX) VOP_ISLOCKED is needed?
121	 */
122	if ((mp->mnt_vnodecovered->v_op == null_vnodeop_p) &&
123		VOP_ISLOCKED(mp->mnt_vnodecovered, NULL)) {
124		VOP_UNLOCK(mp->mnt_vnodecovered, 0, td);
125		isvnunlocked = 1;
126	}
127	/*
128	 * Find lower node
129	 */
130	NDINIT(ndp, LOOKUP, FOLLOW|WANTPARENT|LOCKLEAF,
131		UIO_SYSSPACE, target, td);
132	error = namei(ndp);
133	/*
134	 * Re-lock vnode.
135	 */
136	if (isvnunlocked && !VOP_ISLOCKED(mp->mnt_vnodecovered, NULL))
137		vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY, td);
138
139	if (error)
140		return (error);
141	NDFREE(ndp, NDF_ONLY_PNBUF);
142
143	/*
144	 * Sanity check on lower vnode
145	 */
146	lowerrootvp = ndp->ni_vp;
147
148	vrele(ndp->ni_dvp);
149	ndp->ni_dvp = NULLVP;
150
151	/*
152	 * Check multi null mount to avoid `lock against myself' panic.
153	 */
154	if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) {
155		NULLFSDEBUG("nullfs_mount: multi null mount?\n");
156		vput(lowerrootvp);
157		return (EDEADLK);
158	}
159
160	xmp = (struct null_mount *) malloc(sizeof(struct null_mount),
161				M_NULLFSMNT, M_WAITOK);	/* XXX */
162
163	/*
164	 * Save reference to underlying FS
165	 */
166	xmp->nullm_vfs = lowerrootvp->v_mount;
167
168	/*
169	 * Save reference.  Each mount also holds
170	 * a reference on the root vnode.
171	 */
172	error = null_node_create(mp, lowerrootvp, &vp);
173	/*
174	 * Unlock the node (either the lower or the alias)
175	 */
176	VOP_UNLOCK(vp, 0, td);
177	/*
178	 * Make sure the node alias worked
179	 */
180	if (error) {
181		vrele(lowerrootvp);
182		free(xmp, M_NULLFSMNT);	/* XXX */
183		return (error);
184	}
185
186	/*
187	 * Keep a held reference to the root vnode.
188	 * It is vrele'd in nullfs_unmount.
189	 */
190	nullm_rootvp = vp;
191	nullm_rootvp->v_flag |= VROOT;
192	xmp->nullm_rootvp = nullm_rootvp;
193	if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL)
194		mp->mnt_flag |= MNT_LOCAL;
195	mp->mnt_data = (qaddr_t) xmp;
196	vfs_getnewfsid(mp);
197
198	(void) copystr(target, mp->mnt_stat.f_mntfromname,
199	    MNAMELEN - 1, &size);
200	bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size);
201	(void)nullfs_statfs(mp, &mp->mnt_stat, td);
202	NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n",
203		mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
204	return (0);
205}
206
207/*
208 * VFS start.  Nothing needed here - the start routine
209 * on the underlying filesystem will have been called
210 * when that filesystem was mounted.
211 */
212static int
213nullfs_start(mp, flags, td)
214	struct mount *mp;
215	int flags;
216	struct thread *td;
217{
218	return (0);
219	/* return VFS_START(MOUNTTONULLMOUNT(mp)->nullm_vfs, flags, td); */
220}
221
222/*
223 * Free reference to null layer
224 */
225static int
226nullfs_unmount(mp, mntflags, td)
227	struct mount *mp;
228	int mntflags;
229	struct thread *td;
230{
231	void *mntdata;
232	int error;
233	int flags = 0;
234
235	NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp);
236
237	if (mntflags & MNT_FORCE)
238		flags |= FORCECLOSE;
239
240	/* There is 1 extra root vnode reference (nullm_rootvp). */
241	error = vflush(mp, 1, flags);
242	if (error)
243		return (error);
244
245	/*
246	 * Finally, throw away the null_mount structure
247	 */
248	mntdata = mp->mnt_data;
249	mp->mnt_data = 0;
250	free(mntdata, M_NULLFSMNT);
251	return 0;
252}
253
254static int
255nullfs_root(mp, vpp)
256	struct mount *mp;
257	struct vnode **vpp;
258{
259	struct thread *td = curthread;	/* XXX */
260	struct vnode *vp;
261
262	NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp,
263	    (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp,
264	    (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp));
265
266	/*
267	 * Return locked reference to root.
268	 */
269	vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp;
270	VREF(vp);
271
272#ifdef NULLFS_DEBUG
273	if (VOP_ISLOCKED(vp, NULL)) {
274		Debugger("root vnode is locked.\n");
275		vrele(vp);
276		return (EDEADLK);
277	}
278#endif
279	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
280	*vpp = vp;
281	return 0;
282}
283
284static int
285nullfs_quotactl(mp, cmd, uid, arg, td)
286	struct mount *mp;
287	int cmd;
288	uid_t uid;
289	caddr_t arg;
290	struct thread *td;
291{
292	return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, td);
293}
294
295static int
296nullfs_statfs(mp, sbp, td)
297	struct mount *mp;
298	struct statfs *sbp;
299	struct thread *td;
300{
301	int error;
302	struct statfs mstat;
303
304	NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp,
305	    (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp,
306	    (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp));
307
308	bzero(&mstat, sizeof(mstat));
309
310	error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, td);
311	if (error)
312		return (error);
313
314	/* now copy across the "interesting" information and fake the rest */
315	sbp->f_type = mstat.f_type;
316	sbp->f_flags = mstat.f_flags;
317	sbp->f_bsize = mstat.f_bsize;
318	sbp->f_iosize = mstat.f_iosize;
319	sbp->f_blocks = mstat.f_blocks;
320	sbp->f_bfree = mstat.f_bfree;
321	sbp->f_bavail = mstat.f_bavail;
322	sbp->f_files = mstat.f_files;
323	sbp->f_ffree = mstat.f_ffree;
324	if (sbp != &mp->mnt_stat) {
325		bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid));
326		bcopy(mp->mnt_stat.f_mntonname, sbp->f_mntonname, MNAMELEN);
327		bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN);
328	}
329	return (0);
330}
331
332static int
333nullfs_sync(mp, waitfor, cred, td)
334	struct mount *mp;
335	int waitfor;
336	struct ucred *cred;
337	struct thread *td;
338{
339	/*
340	 * XXX - Assumes no data cached at null layer.
341	 */
342	return (0);
343}
344
345static int
346nullfs_vget(mp, ino, flags, vpp)
347	struct mount *mp;
348	ino_t ino;
349	int flags;
350	struct vnode **vpp;
351{
352	int error;
353	error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp);
354	if (error)
355		return (error);
356
357	return (null_node_create(mp, *vpp, vpp));
358}
359
360static int
361nullfs_fhtovp(mp, fidp, vpp)
362	struct mount *mp;
363	struct fid *fidp;
364	struct vnode **vpp;
365{
366	int error;
367	error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, vpp);
368	if (error)
369		return (error);
370
371	return (null_node_create(mp, *vpp, vpp));
372}
373
374static int
375nullfs_checkexp(mp, nam, extflagsp, credanonp)
376	struct mount *mp;
377	struct sockaddr *nam;
378	int *extflagsp;
379	struct ucred **credanonp;
380{
381
382	return VFS_CHECKEXP(MOUNTTONULLMOUNT(mp)->nullm_vfs, nam,
383		extflagsp, credanonp);
384}
385
386static int
387nullfs_vptofh(vp, fhp)
388	struct vnode *vp;
389	struct fid *fhp;
390{
391	return VFS_VPTOFH(NULLVPTOLOWERVP(vp), fhp);
392}
393
394static int
395nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname, td)
396	struct mount *mp;
397	int cmd;
398	struct vnode *filename_vp;
399	int namespace;
400	const char *attrname;
401	struct thread *td;
402{
403	return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, filename_vp,
404	    namespace, attrname, td);
405}
406
407
408static struct vfsops null_vfsops = {
409	NULL,
410	nullfs_start,
411	nullfs_unmount,
412	nullfs_root,
413	nullfs_quotactl,
414	nullfs_statfs,
415	nullfs_sync,
416	nullfs_vget,
417	nullfs_fhtovp,
418	nullfs_checkexp,
419	nullfs_vptofh,
420	nullfs_init,
421	nullfs_uninit,
422	nullfs_extattrctl,
423	nullfs_mount,
424};
425
426VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK);
427