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 * $FreeBSD$
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/racct.h>
51#include <sys/resourcevar.h>
52#include <sys/vnode.h>
53
54#include <fs/fdescfs/fdesc.h>
55
56static MALLOC_DEFINE(M_FDESCMNT, "fdesc_mount", "FDESC mount structure");
57
58static vfs_cmount_t	fdesc_cmount;
59static vfs_mount_t	fdesc_mount;
60static vfs_unmount_t	fdesc_unmount;
61static vfs_statfs_t	fdesc_statfs;
62static vfs_root_t	fdesc_root;
63
64/*
65 * Compatibility shim for old mount(2) system call.
66 */
67int
68fdesc_cmount(struct mntarg *ma, void *data, uint64_t flags)
69{
70	return kernel_mount(ma, flags);
71}
72
73/*
74 * Mount the per-process file descriptors (/dev/fd)
75 */
76static int
77fdesc_mount(struct mount *mp)
78{
79	int error = 0;
80	struct fdescmount *fmp;
81	struct vnode *rvp;
82
83	/*
84	 * Update is a no-op
85	 */
86	if (mp->mnt_flag & (MNT_UPDATE | MNT_ROOTFS))
87		return (EOPNOTSUPP);
88
89	fmp = malloc(sizeof(struct fdescmount),
90				M_FDESCMNT, M_WAITOK);	/* XXX */
91
92	/*
93	 * We need to initialize a few bits of our local mount point struct to
94	 * avoid confusion in allocvp.
95	 */
96	mp->mnt_data = (qaddr_t) fmp;
97	fmp->flags = 0;
98	error = fdesc_allocvp(Froot, -1, FD_ROOT, mp, &rvp);
99	if (error) {
100		free(fmp, M_FDESCMNT);
101		mp->mnt_data = 0;
102		return (error);
103	}
104	rvp->v_type = VDIR;
105	rvp->v_vflag |= VV_ROOT;
106	fmp->f_root = rvp;
107	VOP_UNLOCK(rvp, 0);
108	/* XXX -- don't mark as local to work around fts() problems */
109	/*mp->mnt_flag |= MNT_LOCAL;*/
110	MNT_ILOCK(mp);
111	mp->mnt_kern_flag |= MNTK_MPSAFE;
112	MNT_IUNLOCK(mp);
113	vfs_getnewfsid(mp);
114
115	vfs_mountedfrom(mp, "fdescfs");
116	return (0);
117}
118
119static int
120fdesc_unmount(mp, mntflags)
121	struct mount *mp;
122	int mntflags;
123{
124	struct fdescmount *fmp;
125	caddr_t data;
126	int error;
127	int flags = 0;
128
129	fmp = (struct fdescmount *)mp->mnt_data;
130	if (mntflags & MNT_FORCE) {
131		/* The hash mutex protects the private mount flags. */
132		mtx_lock(&fdesc_hashmtx);
133		fmp->flags |= FMNT_UNMOUNTF;
134		mtx_unlock(&fdesc_hashmtx);
135		flags |= FORCECLOSE;
136	}
137
138	/*
139	 * Clear out buffer cache.  I don't think we
140	 * ever get anything cached at this level at the
141	 * moment, but who knows...
142	 *
143	 * There is 1 extra root vnode reference corresponding
144	 * to f_root.
145	 */
146	if ((error = vflush(mp, 1, flags, curthread)) != 0)
147		return (error);
148
149	/*
150	 * Finally, throw away the fdescmount structure. Hold the hashmtx to
151	 * protect the fdescmount structure.
152	 */
153	mtx_lock(&fdesc_hashmtx);
154	data = mp->mnt_data;
155	mp->mnt_data = 0;
156	mtx_unlock(&fdesc_hashmtx);
157	free(data, M_FDESCMNT);	/* XXX */
158
159	return (0);
160}
161
162static int
163fdesc_root(mp, flags, vpp)
164	struct mount *mp;
165	int flags;
166	struct vnode **vpp;
167{
168	struct vnode *vp;
169
170	/*
171	 * Return locked reference to root.
172	 */
173	vp = VFSTOFDESC(mp)->f_root;
174	vget(vp, LK_EXCLUSIVE | LK_RETRY, curthread);
175	*vpp = vp;
176	return (0);
177}
178
179static int
180fdesc_statfs(mp, sbp)
181	struct mount *mp;
182	struct statfs *sbp;
183{
184	struct thread *td;
185	struct filedesc *fdp;
186	int lim;
187	int i;
188	int last;
189	int freefd;
190	uint64_t limit;
191
192	td = curthread;
193
194	/*
195	 * Compute number of free file descriptors.
196	 * [ Strange results will ensue if the open file
197	 * limit is ever reduced below the current number
198	 * of open files... ]
199	 */
200	PROC_LOCK(td->td_proc);
201	lim = lim_cur(td->td_proc, RLIMIT_NOFILE);
202	PROC_UNLOCK(td->td_proc);
203	fdp = td->td_proc->p_fd;
204	FILEDESC_SLOCK(fdp);
205	limit = racct_get_limit(td->td_proc, RACCT_NOFILE);
206	if (lim > limit)
207		lim = limit;
208	last = min(fdp->fd_nfiles, lim);
209	freefd = 0;
210	for (i = fdp->fd_freefile; i < last; i++)
211		if (fdp->fd_ofiles[i] == NULL)
212			freefd++;
213
214	/*
215	 * Adjust for the fact that the fdesc array may not
216	 * have been fully allocated yet.
217	 */
218	if (fdp->fd_nfiles < lim)
219		freefd += (lim - fdp->fd_nfiles);
220	FILEDESC_SUNLOCK(fdp);
221
222	sbp->f_flags = 0;
223	sbp->f_bsize = DEV_BSIZE;
224	sbp->f_iosize = DEV_BSIZE;
225	sbp->f_blocks = 2;		/* 1K to keep df happy */
226	sbp->f_bfree = 0;
227	sbp->f_bavail = 0;
228	sbp->f_files = lim + 1;		/* Allow for "." */
229	sbp->f_ffree = freefd;		/* See comments above */
230	return (0);
231}
232
233static struct vfsops fdesc_vfsops = {
234	.vfs_cmount =		fdesc_cmount,
235	.vfs_init =		fdesc_init,
236	.vfs_mount =		fdesc_mount,
237	.vfs_root =		fdesc_root,
238	.vfs_statfs =		fdesc_statfs,
239	.vfs_uninit =		fdesc_uninit,
240	.vfs_unmount =		fdesc_unmount,
241};
242
243VFS_SET(fdesc_vfsops, fdescfs, VFCF_SYNTHETIC);
244