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/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); 239