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/8.0/sys/fs/fdescfs/fdesc_vfsops.c 191990 2009-05-11 15:33:26Z attilio $
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
55 static MALLOC_DEFINE(M_FDESCMNT, "fdesc_mount", "FDESC mount structure");
56
57 static vfs_cmount_t fdesc_cmount;
58 static vfs_mount_t fdesc_mount;
59 static vfs_unmount_t fdesc_unmount;
60 static vfs_statfs_t fdesc_statfs;
61 static vfs_root_t fdesc_root;
62
63 /*
64 * Compatibility shim for old mount(2) system call.
65 */
66 int
67 fdesc_cmount(struct mntarg *ma, void *data, int flags)
68 {
69 return kernel_mount(ma, flags);
70 }
71
72 /*
73 * Mount the per-process file descriptors (/dev/fd)
74 */
75 static int
76 fdesc_mount(struct mount *mp)
77 {
78 int error = 0;
79 struct fdescmount *fmp;
80 struct vnode *rvp;
81
82 /*
83 * Update is a no-op
84 */
85 if (mp->mnt_flag & (MNT_UPDATE | MNT_ROOTFS))
86 return (EOPNOTSUPP);
87
88 fmp = malloc(sizeof(struct fdescmount),
89 M_FDESCMNT, M_WAITOK); /* XXX */
90
91 /*
92 * We need to initialize a few bits of our local mount point struct to
93 * avoid confusion in allocvp.
94 */
95 mp->mnt_data = (qaddr_t) fmp;
96 fmp->flags = 0;
97 error = fdesc_allocvp(Froot, -1, FD_ROOT, mp, &rvp);
98 if (error) {
99 free(fmp, M_FDESCMNT);
100 mp->mnt_data = 0;
101 return (error);
102 }
103 rvp->v_type = VDIR;
104 rvp->v_vflag |= VV_ROOT;
105 fmp->f_root = rvp;
106 VOP_UNLOCK(rvp, 0);
107 /* XXX -- don't mark as local to work around fts() problems */
108 /*mp->mnt_flag |= MNT_LOCAL;*/
109 MNT_ILOCK(mp);
110 mp->mnt_kern_flag |= MNTK_MPSAFE;
111 MNT_IUNLOCK(mp);
112 vfs_getnewfsid(mp);
113
114 vfs_mountedfrom(mp, "fdescfs");
115 return (0);
116 }
117
118 static int
119 fdesc_unmount(mp, mntflags)
120 struct mount *mp;
121 int mntflags;
122 {
123 struct fdescmount *fmp;
124 caddr_t data;
125 int error;
126 int flags = 0;
127
128 fmp = (struct fdescmount *)mp->mnt_data;
129 if (mntflags & MNT_FORCE) {
130 /* The hash mutex protects the private mount flags. */
131 mtx_lock(&fdesc_hashmtx);
132 fmp->flags |= FMNT_UNMOUNTF;
133 mtx_unlock(&fdesc_hashmtx);
134 flags |= FORCECLOSE;
135 }
136
137 /*
138 * Clear out buffer cache. I don't think we
139 * ever get anything cached at this level at the
140 * moment, but who knows...
141 *
142 * There is 1 extra root vnode reference corresponding
143 * to f_root.
144 */
145 if ((error = vflush(mp, 1, flags, curthread)) != 0)
146 return (error);
147
148 /*
149 * Finally, throw away the fdescmount structure. Hold the hashmtx to
150 * protect the fdescmount structure.
151 */
152 mtx_lock(&fdesc_hashmtx);
153 data = mp->mnt_data;
154 mp->mnt_data = 0;
155 mtx_unlock(&fdesc_hashmtx);
156 free(data, M_FDESCMNT); /* XXX */
157
158 return (0);
159 }
160
161 static int
162 fdesc_root(mp, flags, vpp)
163 struct mount *mp;
164 int flags;
165 struct vnode **vpp;
166 {
167 struct vnode *vp;
168
169 /*
170 * Return locked reference to root.
171 */
172 vp = VFSTOFDESC(mp)->f_root;
173 vget(vp, LK_EXCLUSIVE | LK_RETRY, curthread);
174 *vpp = vp;
175 return (0);
176 }
177
178 static int
179 fdesc_statfs(mp, sbp)
180 struct mount *mp;
181 struct statfs *sbp;
182 {
183 struct thread *td;
184 struct filedesc *fdp;
185 int lim;
186 int i;
187 int last;
188 int freefd;
189
190 td = curthread;
191
192 /*
193 * Compute number of free file descriptors.
194 * [ Strange results will ensue if the open file
195 * limit is ever reduced below the current number
196 * of open files... ]
197 */
198 PROC_LOCK(td->td_proc);
199 lim = lim_cur(td->td_proc, RLIMIT_NOFILE);
200 PROC_UNLOCK(td->td_proc);
201 fdp = td->td_proc->p_fd;
202 FILEDESC_SLOCK(fdp);
203 last = min(fdp->fd_nfiles, lim);
204 freefd = 0;
205 for (i = fdp->fd_freefile; i < last; i++)
206 if (fdp->fd_ofiles[i] == NULL)
207 freefd++;
208
209 /*
210 * Adjust for the fact that the fdesc array may not
211 * have been fully allocated yet.
212 */
213 if (fdp->fd_nfiles < lim)
214 freefd += (lim - fdp->fd_nfiles);
215 FILEDESC_SUNLOCK(fdp);
216
217 sbp->f_flags = 0;
218 sbp->f_bsize = DEV_BSIZE;
219 sbp->f_iosize = DEV_BSIZE;
220 sbp->f_blocks = 2; /* 1K to keep df happy */
221 sbp->f_bfree = 0;
222 sbp->f_bavail = 0;
223 sbp->f_files = lim + 1; /* Allow for "." */
224 sbp->f_ffree = freefd; /* See comments above */
225 return (0);
226 }
227
228 static struct vfsops fdesc_vfsops = {
229 .vfs_cmount = fdesc_cmount,
230 .vfs_init = fdesc_init,
231 .vfs_mount = fdesc_mount,
232 .vfs_root = fdesc_root,
233 .vfs_statfs = fdesc_statfs,
234 .vfs_uninit = fdesc_uninit,
235 .vfs_unmount = fdesc_unmount,
236 };
237
238 VFS_SET(fdesc_vfsops, fdescfs, VFCF_SYNTHETIC);
Cache object: d8a3d0456ed6bdd5bebf20c6bb1c67de
|