xref: /freebsd/sys/fs/nullfs/null_vfsops.c (revision 1e413cf93298b5b97441a21d9a50fdcd0ee9945e)
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  * 4. Neither the name of the University nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  *
32  *	@(#)null_vfsops.c	8.2 (Berkeley) 1/21/94
33  *
34  * @(#)lofs_vfsops.c	1.2 (Berkeley) 6/18/92
35  * $FreeBSD$
36  */
37 
38 /*
39  * Null Layer
40  * (See null_vnops.c for a description of what this does.)
41  */
42 
43 #include <sys/param.h>
44 #include <sys/systm.h>
45 #include <sys/kernel.h>
46 #include <sys/lock.h>
47 #include <sys/malloc.h>
48 #include <sys/mount.h>
49 #include <sys/namei.h>
50 #include <sys/proc.h>
51 #include <sys/vnode.h>
52 
53 #include <fs/nullfs/null.h>
54 
55 static MALLOC_DEFINE(M_NULLFSMNT, "nullfs_mount", "NULLFS mount structure");
56 
57 static vfs_fhtovp_t	nullfs_fhtovp;
58 static vfs_mount_t	nullfs_mount;
59 static vfs_quotactl_t	nullfs_quotactl;
60 static vfs_root_t	nullfs_root;
61 static vfs_sync_t	nullfs_sync;
62 static vfs_statfs_t	nullfs_statfs;
63 static vfs_unmount_t	nullfs_unmount;
64 static vfs_vget_t	nullfs_vget;
65 static vfs_extattrctl_t	nullfs_extattrctl;
66 
67 /*
68  * Mount null layer
69  */
70 static int
71 nullfs_mount(struct mount *mp, struct thread *td)
72 {
73 	int error = 0;
74 	struct vnode *lowerrootvp, *vp;
75 	struct vnode *nullm_rootvp;
76 	struct null_mount *xmp;
77 	char *target;
78 	int isvnunlocked = 0, len;
79 	struct nameidata nd, *ndp = &nd;
80 
81 	NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp);
82 
83 	if (mp->mnt_flag & MNT_ROOTFS)
84 		return (EOPNOTSUPP);
85 	/*
86 	 * Update is a no-op
87 	 */
88 	if (mp->mnt_flag & MNT_UPDATE) {
89 		/*
90 		 * Only support update mounts for NFS export.
91 		 */
92 		if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0))
93 			return (0);
94 		else
95 			return (EOPNOTSUPP);
96 	}
97 
98 	/*
99 	 * Get argument
100 	 */
101 	error = vfs_getopt(mp->mnt_optnew, "target", (void **)&target, &len);
102 	if (error || target[len - 1] != '\0')
103 		return (EINVAL);
104 
105 	/*
106 	 * Unlock lower node to avoid deadlock.
107 	 * (XXX) VOP_ISLOCKED is needed?
108 	 */
109 	if ((mp->mnt_vnodecovered->v_op == &null_vnodeops) &&
110 		VOP_ISLOCKED(mp->mnt_vnodecovered, NULL)) {
111 		VOP_UNLOCK(mp->mnt_vnodecovered, 0);
112 		isvnunlocked = 1;
113 	}
114 	/*
115 	 * Find lower node
116 	 */
117 	NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF,
118 		UIO_SYSSPACE, target, td);
119 	error = namei(ndp);
120 	/*
121 	 * Re-lock vnode.
122 	 */
123 	if (isvnunlocked && !VOP_ISLOCKED(mp->mnt_vnodecovered, NULL))
124 		vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY);
125 
126 	if (error)
127 		return (error);
128 	NDFREE(ndp, NDF_ONLY_PNBUF);
129 
130 	/*
131 	 * Sanity check on lower vnode
132 	 */
133 	lowerrootvp = ndp->ni_vp;
134 
135 	/*
136 	 * Check multi null mount to avoid `lock against myself' panic.
137 	 */
138 	if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) {
139 		NULLFSDEBUG("nullfs_mount: multi null mount?\n");
140 		vput(lowerrootvp);
141 		return (EDEADLK);
142 	}
143 
144 	xmp = (struct null_mount *) malloc(sizeof(struct null_mount),
145 				M_NULLFSMNT, M_WAITOK);	/* XXX */
146 
147 	/*
148 	 * Save reference to underlying FS
149 	 */
150 	xmp->nullm_vfs = lowerrootvp->v_mount;
151 
152 	/*
153 	 * Save reference.  Each mount also holds
154 	 * a reference on the root vnode.
155 	 */
156 	error = null_nodeget(mp, lowerrootvp, &vp);
157 	/*
158 	 * Make sure the node alias worked
159 	 */
160 	if (error) {
161 		VOP_UNLOCK(vp, 0);
162 		vrele(lowerrootvp);
163 		free(xmp, M_NULLFSMNT);	/* XXX */
164 		return (error);
165 	}
166 
167 	/*
168 	 * Keep a held reference to the root vnode.
169 	 * It is vrele'd in nullfs_unmount.
170 	 */
171 	nullm_rootvp = vp;
172 	nullm_rootvp->v_vflag |= VV_ROOT;
173 	xmp->nullm_rootvp = nullm_rootvp;
174 
175 	/*
176 	 * Unlock the node (either the lower or the alias)
177 	 */
178 	VOP_UNLOCK(vp, 0);
179 
180 	if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) {
181 		MNT_ILOCK(mp);
182 		mp->mnt_flag |= MNT_LOCAL;
183 		MNT_IUNLOCK(mp);
184 	}
185 	MNT_ILOCK(mp);
186 	mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & MNTK_MPSAFE;
187 	MNT_IUNLOCK(mp);
188 	mp->mnt_data =  xmp;
189 	vfs_getnewfsid(mp);
190 
191 	vfs_mountedfrom(mp, target);
192 
193 	NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n",
194 		mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
195 	return (0);
196 }
197 
198 /*
199  * Free reference to null layer
200  */
201 static int
202 nullfs_unmount(mp, mntflags, td)
203 	struct mount *mp;
204 	int mntflags;
205 	struct thread *td;
206 {
207 	void *mntdata;
208 	int error;
209 	int flags = 0;
210 
211 	NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp);
212 
213 	if (mntflags & MNT_FORCE)
214 		flags |= FORCECLOSE;
215 
216 	/* There is 1 extra root vnode reference (nullm_rootvp). */
217 	error = vflush(mp, 1, flags, td);
218 	if (error)
219 		return (error);
220 
221 	/*
222 	 * Finally, throw away the null_mount structure
223 	 */
224 	mntdata = mp->mnt_data;
225 	mp->mnt_data = 0;
226 	free(mntdata, M_NULLFSMNT);
227 	return 0;
228 }
229 
230 static int
231 nullfs_root(mp, flags, vpp, td)
232 	struct mount *mp;
233 	int flags;
234 	struct vnode **vpp;
235 	struct thread *td;
236 {
237 	struct vnode *vp;
238 
239 	NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp,
240 	    (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp,
241 	    (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp));
242 
243 	/*
244 	 * Return locked reference to root.
245 	 */
246 	vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp;
247 	VREF(vp);
248 
249 #ifdef NULLFS_DEBUG
250 	if (VOP_ISLOCKED(vp, NULL))
251 		panic("root vnode is locked.\n");
252 #endif
253 	vn_lock(vp, flags | LK_RETRY);
254 	*vpp = vp;
255 	return 0;
256 }
257 
258 static int
259 nullfs_quotactl(mp, cmd, uid, arg, td)
260 	struct mount *mp;
261 	int cmd;
262 	uid_t uid;
263 	void *arg;
264 	struct thread *td;
265 {
266 	return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, td);
267 }
268 
269 static int
270 nullfs_statfs(mp, sbp, td)
271 	struct mount *mp;
272 	struct statfs *sbp;
273 	struct thread *td;
274 {
275 	int error;
276 	struct statfs mstat;
277 
278 	NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp,
279 	    (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp,
280 	    (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp));
281 
282 	bzero(&mstat, sizeof(mstat));
283 
284 	error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, td);
285 	if (error)
286 		return (error);
287 
288 	/* now copy across the "interesting" information and fake the rest */
289 	sbp->f_type = mstat.f_type;
290 	sbp->f_flags = mstat.f_flags;
291 	sbp->f_bsize = mstat.f_bsize;
292 	sbp->f_iosize = mstat.f_iosize;
293 	sbp->f_blocks = mstat.f_blocks;
294 	sbp->f_bfree = mstat.f_bfree;
295 	sbp->f_bavail = mstat.f_bavail;
296 	sbp->f_files = mstat.f_files;
297 	sbp->f_ffree = mstat.f_ffree;
298 	return (0);
299 }
300 
301 static int
302 nullfs_sync(mp, waitfor, td)
303 	struct mount *mp;
304 	int waitfor;
305 	struct thread *td;
306 {
307 	/*
308 	 * XXX - Assumes no data cached at null layer.
309 	 */
310 	return (0);
311 }
312 
313 static int
314 nullfs_vget(mp, ino, flags, vpp)
315 	struct mount *mp;
316 	ino_t ino;
317 	int flags;
318 	struct vnode **vpp;
319 {
320 	int error;
321 	error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp);
322 	if (error)
323 		return (error);
324 
325 	return (null_nodeget(mp, *vpp, vpp));
326 }
327 
328 static int
329 nullfs_fhtovp(mp, fidp, vpp)
330 	struct mount *mp;
331 	struct fid *fidp;
332 	struct vnode **vpp;
333 {
334 	int error;
335 	error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, vpp);
336 	if (error)
337 		return (error);
338 
339 	return (null_nodeget(mp, *vpp, vpp));
340 }
341 
342 static int
343 nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname, td)
344 	struct mount *mp;
345 	int cmd;
346 	struct vnode *filename_vp;
347 	int namespace;
348 	const char *attrname;
349 	struct thread *td;
350 {
351 	return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, filename_vp,
352 	    namespace, attrname, td);
353 }
354 
355 
356 static struct vfsops null_vfsops = {
357 	.vfs_extattrctl =	nullfs_extattrctl,
358 	.vfs_fhtovp =		nullfs_fhtovp,
359 	.vfs_init =		nullfs_init,
360 	.vfs_mount =		nullfs_mount,
361 	.vfs_quotactl =		nullfs_quotactl,
362 	.vfs_root =		nullfs_root,
363 	.vfs_statfs =		nullfs_statfs,
364 	.vfs_sync =		nullfs_sync,
365 	.vfs_uninit =		nullfs_uninit,
366 	.vfs_unmount =		nullfs_unmount,
367 	.vfs_vget =		nullfs_vget,
368 };
369 
370 VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK);
371