fdesc_vfsops.c revision 144058 
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 *	@(#)fdesc_vfsops.c	8.4 (Berkeley) 1/21/94
33 *
34 * $FreeBSD: head/sys/fs/fdescfs/fdesc_vfsops.c 144058 2005-03-24 07:36:16Z jeff $
35 */
36
37/*
38 * /dev/fd Filesystem
39 */
40
41#include <sys/param.h>
42#include <sys/systm.h>
43#include <sys/filedesc.h>
44#include <sys/kernel.h>
45#include <sys/lock.h>
46#include <sys/mutex.h>
47#include <sys/malloc.h>
48#include <sys/mount.h>
49#include <sys/proc.h>
50#include <sys/resourcevar.h>
51#include <sys/vnode.h>
52
53#include <fs/fdescfs/fdesc.h>
54
55static MALLOC_DEFINE(M_FDESCMNT, "FDESC mount", "FDESC mount structure");
56
57static vfs_mount_t	fdesc_mount;
58static vfs_unmount_t	fdesc_unmount;
59static vfs_statfs_t	fdesc_statfs;
60static vfs_root_t	fdesc_root;
61
62/*
63 * Mount the per-process file descriptors (/dev/fd)
64 */
65static int
66fdesc_mount(struct mount *mp, struct thread *td)
67{
68	int error = 0;
69	struct fdescmount *fmp;
70	struct vnode *rvp;
71
72	/*
73	 * Update is a no-op
74	 */
75	if (mp->mnt_flag & (MNT_UPDATE | MNT_ROOTFS))
76		return (EOPNOTSUPP);
77
78	error = fdesc_allocvp(Froot, FD_ROOT, mp, &rvp, td);
79	if (error)
80		return (error);
81
82	MALLOC(fmp, struct fdescmount *, sizeof(struct fdescmount),
83				M_FDESCMNT, M_WAITOK);	/* XXX */
84	rvp->v_type = VDIR;
85	rvp->v_vflag |= VV_ROOT;
86	fmp->f_root = rvp;
87	/* XXX -- don't mark as local to work around fts() problems */
88	/*mp->mnt_flag |= MNT_LOCAL;*/
89	mp->mnt_data = (qaddr_t) fmp;
90	vfs_getnewfsid(mp);
91
92	vfs_mountedfrom(mp, "fdescfs");
93	return (0);
94}
95
96static int
97fdesc_unmount(mp, mntflags, td)
98	struct mount *mp;
99	int mntflags;
100	struct thread *td;
101{
102	int error;
103	int flags = 0;
104
105	if (mntflags & MNT_FORCE)
106		flags |= FORCECLOSE;
107
108	/*
109	 * Clear out buffer cache.  I don't think we
110	 * ever get anything cached at this level at the
111	 * moment, but who knows...
112	 *
113	 * There is 1 extra root vnode reference corresponding
114	 * to f_root.
115	 */
116	if ((error = vflush(mp, 1, flags, td)) != 0)
117		return (error);
118
119	/*
120	 * Finally, throw away the fdescmount structure
121	 */
122	free(mp->mnt_data, M_FDESCMNT);	/* XXX */
123	mp->mnt_data = 0;
124
125	return (0);
126}
127
128static int
129fdesc_root(mp, flags, vpp, td)
130	struct mount *mp;
131	int flags;
132	struct vnode **vpp;
133	struct thread *td;
134{
135	struct vnode *vp;
136
137	/*
138	 * Return locked reference to root.
139	 */
140	vp = VFSTOFDESC(mp)->f_root;
141	VREF(vp);
142	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
143	*vpp = vp;
144	return (0);
145}
146
147static int
148fdesc_statfs(mp, sbp, td)
149	struct mount *mp;
150	struct statfs *sbp;
151	struct thread *td;
152{
153	struct filedesc *fdp;
154	int lim;
155	int i;
156	int last;
157	int freefd;
158
159	/*
160	 * Compute number of free file descriptors.
161	 * [ Strange results will ensue if the open file
162	 * limit is ever reduced below the current number
163	 * of open files... ]
164	 */
165	PROC_LOCK(td->td_proc);
166	lim = lim_cur(td->td_proc, RLIMIT_NOFILE);
167	PROC_UNLOCK(td->td_proc);
168	fdp = td->td_proc->p_fd;
169	FILEDESC_LOCK_FAST(fdp);
170	last = min(fdp->fd_nfiles, lim);
171	freefd = 0;
172	for (i = fdp->fd_freefile; i < last; i++)
173		if (fdp->fd_ofiles[i] == NULL)
174			freefd++;
175
176	/*
177	 * Adjust for the fact that the fdesc array may not
178	 * have been fully allocated yet.
179	 */
180	if (fdp->fd_nfiles < lim)
181		freefd += (lim - fdp->fd_nfiles);
182	FILEDESC_UNLOCK_FAST(fdp);
183
184	sbp->f_flags = 0;
185	sbp->f_bsize = DEV_BSIZE;
186	sbp->f_iosize = DEV_BSIZE;
187	sbp->f_blocks = 2;		/* 1K to keep df happy */
188	sbp->f_bfree = 0;
189	sbp->f_bavail = 0;
190	sbp->f_files = lim + 1;		/* Allow for "." */
191	sbp->f_ffree = freefd;		/* See comments above */
192	return (0);
193}
194
195static struct vfsops fdesc_vfsops = {
196	.vfs_init =		fdesc_init,
197	.vfs_mount =		fdesc_mount,
198	.vfs_root =		fdesc_root,
199	.vfs_statfs =		fdesc_statfs,
200	.vfs_unmount =		fdesc_unmount,
201};
202
203VFS_SET(fdesc_vfsops, fdescfs, VFCF_SYNTHETIC);
204