xref: /freebsd/sys/fs/devfs/devfs_vfsops.c (revision 0f2bd1e89db1a2f09268edea21e0ead329e092df)
1 /*-
2  * Copyright (c) 1992, 1993, 1995
3  *	The Regents of the University of California.  All rights reserved.
4  * Copyright (c) 2000
5  *	Poul-Henning Kamp.  All rights reserved.
6  *
7  * This code is derived from software donated to Berkeley by
8  * Jan-Simon Pendry.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  *
31  *	@(#)kernfs_vfsops.c	8.10 (Berkeley) 5/14/95
32  * From: FreeBSD: src/sys/miscfs/kernfs/kernfs_vfsops.c 1.36
33  *
34  * $FreeBSD$
35  */
36 
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/kernel.h>
40 #include <sys/lock.h>
41 #include <sys/malloc.h>
42 #include <sys/mount.h>
43 #include <sys/proc.h>
44 #include <sys/sx.h>
45 #include <sys/vnode.h>
46 #include <sys/limits.h>
47 
48 #include <fs/devfs/devfs.h>
49 
50 static struct unrhdr	*devfs_unr;
51 
52 MALLOC_DEFINE(M_DEVFS, "DEVFS", "DEVFS data");
53 
54 static vfs_mount_t	devfs_mount;
55 static vfs_unmount_t	devfs_unmount;
56 static vfs_root_t	devfs_root;
57 static vfs_statfs_t	devfs_statfs;
58 
59 /*
60  * Mount the filesystem
61  */
62 static int
63 devfs_mount(struct mount *mp)
64 {
65 	int error;
66 	struct devfs_mount *fmp;
67 	struct vnode *rvp;
68 
69 	if (devfs_unr == NULL)
70 		devfs_unr = new_unrhdr(0, INT_MAX, NULL);
71 
72 	error = 0;
73 
74 	if (mp->mnt_flag & (MNT_UPDATE | MNT_ROOTFS))
75 		return (EOPNOTSUPP);
76 
77 	fmp = malloc(sizeof *fmp, M_DEVFS, M_WAITOK | M_ZERO);
78 	fmp->dm_idx = alloc_unr(devfs_unr);
79 	sx_init(&fmp->dm_lock, "devfsmount");
80 	fmp->dm_holdcnt = 1;
81 
82 	MNT_ILOCK(mp);
83 	mp->mnt_flag |= MNT_LOCAL;
84 	mp->mnt_kern_flag |= MNTK_MPSAFE | MNTK_LOOKUP_SHARED |
85 	    MNTK_EXTENDED_SHARED;
86 #ifdef MAC
87 	mp->mnt_flag |= MNT_MULTILABEL;
88 #endif
89 	MNT_IUNLOCK(mp);
90 	fmp->dm_mount = mp;
91 	mp->mnt_data = (void *) fmp;
92 	vfs_getnewfsid(mp);
93 
94 	fmp->dm_rootdir = devfs_vmkdir(fmp, NULL, 0, NULL, DEVFS_ROOTINO);
95 
96 	error = devfs_root(mp, LK_EXCLUSIVE, &rvp);
97 	if (error) {
98 		sx_destroy(&fmp->dm_lock);
99 		free_unr(devfs_unr, fmp->dm_idx);
100 		free(fmp, M_DEVFS);
101 		return (error);
102 	}
103 
104 	VOP_UNLOCK(rvp, 0);
105 
106 	vfs_mountedfrom(mp, "devfs");
107 
108 	return (0);
109 }
110 
111 void
112 devfs_unmount_final(struct devfs_mount *fmp)
113 {
114 	sx_destroy(&fmp->dm_lock);
115 	free(fmp, M_DEVFS);
116 }
117 
118 static int
119 devfs_unmount(struct mount *mp, int mntflags)
120 {
121 	int error;
122 	int flags = 0;
123 	struct devfs_mount *fmp;
124 	int hold;
125 	u_int idx;
126 
127 	fmp = VFSTODEVFS(mp);
128 	KASSERT(fmp->dm_mount != NULL,
129 		("devfs_unmount unmounted devfs_mount"));
130 	/* There is 1 extra root vnode reference from devfs_mount(). */
131 	error = vflush(mp, 1, flags, curthread);
132 	if (error)
133 		return (error);
134 	sx_xlock(&fmp->dm_lock);
135 	devfs_cleanup(fmp);
136 	devfs_rules_cleanup(fmp);
137 	fmp->dm_mount = NULL;
138 	hold = --fmp->dm_holdcnt;
139 	mp->mnt_data = NULL;
140 	idx = fmp->dm_idx;
141 	sx_xunlock(&fmp->dm_lock);
142 	free_unr(devfs_unr, idx);
143 	if (hold == 0)
144 		devfs_unmount_final(fmp);
145 	return 0;
146 }
147 
148 /* Return locked reference to root.  */
149 
150 static int
151 devfs_root(struct mount *mp, int flags, struct vnode **vpp)
152 {
153 	int error;
154 	struct vnode *vp;
155 	struct devfs_mount *dmp;
156 
157 	dmp = VFSTODEVFS(mp);
158 	sx_xlock(&dmp->dm_lock);
159 	error = devfs_allocv(dmp->dm_rootdir, mp, LK_EXCLUSIVE, &vp);
160 	if (error)
161 		return (error);
162 	vp->v_vflag |= VV_ROOT;
163 	*vpp = vp;
164 	return (0);
165 }
166 
167 static int
168 devfs_statfs(struct mount *mp, struct statfs *sbp)
169 {
170 
171 	sbp->f_flags = 0;
172 	sbp->f_bsize = DEV_BSIZE;
173 	sbp->f_iosize = DEV_BSIZE;
174 	sbp->f_blocks = 2;		/* 1K to keep df happy */
175 	sbp->f_bfree = 0;
176 	sbp->f_bavail = 0;
177 	sbp->f_files = 0;
178 	sbp->f_ffree = 0;
179 	return (0);
180 }
181 
182 static struct vfsops devfs_vfsops = {
183 	.vfs_mount =		devfs_mount,
184 	.vfs_root =		devfs_root,
185 	.vfs_statfs =		devfs_statfs,
186 	.vfs_unmount =		devfs_unmount,
187 };
188 
189 VFS_SET(devfs_vfsops, devfs, VFCF_SYNTHETIC);
190