1 /*-
2 * Copyright (c) 2007 Pawel Jakub Dawidek <pjd@FreeBSD.org>
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 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29
30 #include <sys/param.h>
31 #include <sys/kernel.h>
32 #include <sys/systm.h>
33 #include <sys/pathname.h>
34 #include <sys/vfs.h>
35 #include <sys/vnode.h>
36
37 int
lookupname(char * dirname,enum uio_seg seg,enum symfollow follow,vnode_t ** dirvpp,vnode_t ** compvpp)38 lookupname(char *dirname, enum uio_seg seg, enum symfollow follow,
39 vnode_t **dirvpp, vnode_t **compvpp)
40 {
41
42 return (lookupnameat(dirname, seg, follow, dirvpp, compvpp, NULL));
43 }
44
45 int
lookupnameat(char * dirname,enum uio_seg seg,enum symfollow follow,vnode_t ** dirvpp,vnode_t ** compvpp,vnode_t * startvp)46 lookupnameat(char *dirname, enum uio_seg seg, enum symfollow follow,
47 vnode_t **dirvpp, vnode_t **compvpp, vnode_t *startvp)
48 {
49 struct nameidata nd;
50 int error, ltype;
51
52 ASSERT(dirvpp == NULL);
53
54 vref(startvp);
55 ltype = VOP_ISLOCKED(startvp);
56 VOP_UNLOCK(startvp, 0);
57 NDINIT_ATVP(&nd, LOOKUP, LOCKLEAF | follow, seg, dirname,
58 startvp, curthread);
59 error = namei(&nd);
60 *compvpp = nd.ni_vp;
61 NDFREE(&nd, NDF_ONLY_PNBUF);
62 vn_lock(startvp, ltype | LK_RETRY);
63 return (error);
64 }
65
66 int
traverse(vnode_t ** cvpp,int lktype)67 traverse(vnode_t **cvpp, int lktype)
68 {
69 vnode_t *cvp;
70 vnode_t *tvp;
71 vfs_t *vfsp;
72 int error;
73
74 cvp = *cvpp;
75 tvp = NULL;
76
77 /*
78 * If this vnode is mounted on, then we transparently indirect
79 * to the vnode which is the root of the mounted file system.
80 * Before we do this we must check that an unmount is not in
81 * progress on this vnode.
82 */
83
84 for (;;) {
85 /*
86 * Reached the end of the mount chain?
87 */
88 vfsp = vn_mountedvfs(cvp);
89 if (vfsp == NULL)
90 break;
91 error = vfs_busy(vfsp, 0);
92 /*
93 * tvp is NULL for *cvpp vnode, which we can't unlock.
94 * At least some callers expect the reference to be
95 * maintained to the original *cvpp
96 */
97 if (tvp != NULL)
98 vput(cvp);
99 if (error)
100 return (error);
101
102 /*
103 * The read lock must be held across the call to VFS_ROOT() to
104 * prevent a concurrent unmount from destroying the vfs.
105 */
106 error = VFS_ROOT(vfsp, lktype, &tvp);
107 vfs_unbusy(vfsp);
108 if (error != 0)
109 return (error);
110 cvp = tvp;
111 }
112
113 *cvpp = cvp;
114 return (0);
115 }
116