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 return kernel_mount(ma, flags); 72 } 73 74 /* 75 * Mount the per-process file descriptors (/dev/fd) 76 */ 77 static int 78 fdesc_mount(struct mount *mp) 79 { 80 int error = 0; 81 struct fdescmount *fmp; 82 struct thread *td = curthread; 83 struct vnode *rvp; 84 85 if (!prison_allow(td->td_ucred, PR_ALLOW_MOUNT_FDESCFS)) 86 return (EPERM); 87 88 /* 89 * Update is a no-op 90 */ 91 if (mp->mnt_flag & (MNT_UPDATE | MNT_ROOTFS)) 92 return (EOPNOTSUPP); 93 94 fmp = malloc(sizeof(struct fdescmount), 95 M_FDESCMNT, M_WAITOK); /* XXX */ 96 97 /* 98 * We need to initialize a few bits of our local mount point struct to 99 * avoid confusion in allocvp. 100 */ 101 mp->mnt_data = (qaddr_t) fmp; 102 fmp->flags = 0; 103 error = fdesc_allocvp(Froot, -1, FD_ROOT, mp, &rvp); 104 if (error) { 105 free(fmp, M_FDESCMNT); 106 mp->mnt_data = NULL; 107 return (error); 108 } 109 rvp->v_type = VDIR; 110 rvp->v_vflag |= VV_ROOT; 111 fmp->f_root = rvp; 112 VOP_UNLOCK(rvp, 0); 113 /* XXX -- don't mark as local to work around fts() problems */ 114 /*mp->mnt_flag |= MNT_LOCAL;*/ 115 vfs_getnewfsid(mp); 116 117 vfs_mountedfrom(mp, "fdescfs"); 118 return (0); 119 } 120 121 static int 122 fdesc_unmount(struct mount *mp, 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 = NULL; 156 mtx_unlock(&fdesc_hashmtx); 157 free(data, M_FDESCMNT); /* XXX */ 158 159 return (0); 160 } 161 162 static int 163 fdesc_root(struct mount *mp, int flags, 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(struct mount *mp, struct statfs *sbp) 178 { 179 struct thread *td; 180 struct filedesc *fdp; 181 int lim; 182 int i; 183 int last; 184 int freefd; 185 uint64_t limit; 186 187 td = curthread; 188 189 /* 190 * Compute number of free file descriptors. 191 * [ Strange results will ensue if the open file 192 * limit is ever reduced below the current number 193 * of open files... ] 194 */ 195 lim = lim_cur(td, RLIMIT_NOFILE); 196 fdp = td->td_proc->p_fd; 197 FILEDESC_SLOCK(fdp); 198 limit = racct_get_limit(td->td_proc, RACCT_NOFILE); 199 if (lim > limit) 200 lim = limit; 201 last = min(fdp->fd_nfiles, lim); 202 freefd = 0; 203 for (i = fdp->fd_freefile; i < last; i++) 204 if (fdp->fd_ofiles[i].fde_file == NULL) 205 freefd++; 206 207 /* 208 * Adjust for the fact that the fdesc array may not 209 * have been fully allocated yet. 210 */ 211 if (fdp->fd_nfiles < lim) 212 freefd += (lim - fdp->fd_nfiles); 213 FILEDESC_SUNLOCK(fdp); 214 215 sbp->f_flags = 0; 216 sbp->f_bsize = DEV_BSIZE; 217 sbp->f_iosize = DEV_BSIZE; 218 sbp->f_blocks = 2; /* 1K to keep df happy */ 219 sbp->f_bfree = 0; 220 sbp->f_bavail = 0; 221 sbp->f_files = lim + 1; /* Allow for "." */ 222 sbp->f_ffree = freefd; /* See comments above */ 223 return (0); 224 } 225 226 static struct vfsops fdesc_vfsops = { 227 .vfs_cmount = fdesc_cmount, 228 .vfs_init = fdesc_init, 229 .vfs_mount = fdesc_mount, 230 .vfs_root = fdesc_root, 231 .vfs_statfs = fdesc_statfs, 232 .vfs_uninit = fdesc_uninit, 233 .vfs_unmount = fdesc_unmount, 234 }; 235 236 VFS_SET(fdesc_vfsops, fdescfs, VFCF_SYNTHETIC | VFCF_JAIL); 237