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: releng/10.0/sys/fs/fdescfs/fdesc_vfsops.c 247602 2013-03-02 00:53:12Z pjd $
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
56 static MALLOC_DEFINE(M_FDESCMNT, "fdesc_mount", "FDESC mount structure");
57
58 static vfs_cmount_t fdesc_cmount;
59 static vfs_mount_t fdesc_mount;
60 static vfs_unmount_t fdesc_unmount;
61 static vfs_statfs_t fdesc_statfs;
62 static vfs_root_t fdesc_root;
63
64 /*
65 * Compatibility shim for old mount(2) system call.
66 */
67 int
68 fdesc_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 */
76 static int
77 fdesc_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 = NULL;
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 vfs_getnewfsid(mp);
111
112 vfs_mountedfrom(mp, "fdescfs");
113 return (0);
114 }
115
116 static int
117 fdesc_unmount(mp, mntflags)
118 struct mount *mp;
119 int mntflags;
120 {
121 struct fdescmount *fmp;
122 caddr_t data;
123 int error;
124 int flags = 0;
125
126 fmp = (struct fdescmount *)mp->mnt_data;
127 if (mntflags & MNT_FORCE) {
128 /* The hash mutex protects the private mount flags. */
129 mtx_lock(&fdesc_hashmtx);
130 fmp->flags |= FMNT_UNMOUNTF;
131 mtx_unlock(&fdesc_hashmtx);
132 flags |= FORCECLOSE;
133 }
134
135 /*
136 * Clear out buffer cache. I don't think we
137 * ever get anything cached at this level at the
138 * moment, but who knows...
139 *
140 * There is 1 extra root vnode reference corresponding
141 * to f_root.
142 */
143 if ((error = vflush(mp, 1, flags, curthread)) != 0)
144 return (error);
145
146 /*
147 * Finally, throw away the fdescmount structure. Hold the hashmtx to
148 * protect the fdescmount structure.
149 */
150 mtx_lock(&fdesc_hashmtx);
151 data = mp->mnt_data;
152 mp->mnt_data = NULL;
153 mtx_unlock(&fdesc_hashmtx);
154 free(data, M_FDESCMNT); /* XXX */
155
156 return (0);
157 }
158
159 static int
160 fdesc_root(mp, flags, vpp)
161 struct mount *mp;
162 int flags;
163 struct vnode **vpp;
164 {
165 struct vnode *vp;
166
167 /*
168 * Return locked reference to root.
169 */
170 vp = VFSTOFDESC(mp)->f_root;
171 vget(vp, LK_EXCLUSIVE | LK_RETRY, curthread);
172 *vpp = vp;
173 return (0);
174 }
175
176 static int
177 fdesc_statfs(mp, sbp)
178 struct mount *mp;
179 struct statfs *sbp;
180 {
181 struct thread *td;
182 struct filedesc *fdp;
183 int lim;
184 int i;
185 int last;
186 int freefd;
187 uint64_t limit;
188
189 td = curthread;
190
191 /*
192 * Compute number of free file descriptors.
193 * [ Strange results will ensue if the open file
194 * limit is ever reduced below the current number
195 * of open files... ]
196 */
197 PROC_LOCK(td->td_proc);
198 lim = lim_cur(td->td_proc, RLIMIT_NOFILE);
199 PROC_UNLOCK(td->td_proc);
200 fdp = td->td_proc->p_fd;
201 FILEDESC_SLOCK(fdp);
202 limit = racct_get_limit(td->td_proc, RACCT_NOFILE);
203 if (lim > limit)
204 lim = limit;
205 last = min(fdp->fd_nfiles, lim);
206 freefd = 0;
207 for (i = fdp->fd_freefile; i < last; i++)
208 if (fdp->fd_ofiles[i].fde_file == NULL)
209 freefd++;
210
211 /*
212 * Adjust for the fact that the fdesc array may not
213 * have been fully allocated yet.
214 */
215 if (fdp->fd_nfiles < lim)
216 freefd += (lim - fdp->fd_nfiles);
217 FILEDESC_SUNLOCK(fdp);
218
219 sbp->f_flags = 0;
220 sbp->f_bsize = DEV_BSIZE;
221 sbp->f_iosize = DEV_BSIZE;
222 sbp->f_blocks = 2; /* 1K to keep df happy */
223 sbp->f_bfree = 0;
224 sbp->f_bavail = 0;
225 sbp->f_files = lim + 1; /* Allow for "." */
226 sbp->f_ffree = freefd; /* See comments above */
227 return (0);
228 }
229
230 static struct vfsops fdesc_vfsops = {
231 .vfs_cmount = fdesc_cmount,
232 .vfs_init = fdesc_init,
233 .vfs_mount = fdesc_mount,
234 .vfs_root = fdesc_root,
235 .vfs_statfs = fdesc_statfs,
236 .vfs_uninit = fdesc_uninit,
237 .vfs_unmount = fdesc_unmount,
238 };
239
240 VFS_SET(fdesc_vfsops, fdescfs, VFCF_SYNTHETIC);
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