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