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 int error = 0; 82 struct fdescmount *fmp; 83 struct thread *td = curthread; 84 struct vnode *rvp; 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 = (qaddr_t) fmp; 103 fmp->flags = 0; 104 error = fdesc_allocvp(Froot, -1, FD_ROOT, mp, &rvp); 105 if (error) { 106 free(fmp, M_FDESCMNT); 107 mp->mnt_data = NULL; 108 return (error); 109 } 110 rvp->v_type = VDIR; 111 rvp->v_vflag |= VV_ROOT; 112 fmp->f_root = rvp; 113 VOP_UNLOCK(rvp, 0); 114 /* XXX -- don't mark as local to work around fts() problems */ 115 /*mp->mnt_flag |= MNT_LOCAL;*/ 116 vfs_getnewfsid(mp); 117 118 vfs_mountedfrom(mp, "fdescfs"); 119 return (0); 120 } 121 122 static int 123 fdesc_unmount(struct mount *mp, int mntflags) 124 { 125 struct fdescmount *fmp; 126 caddr_t data; 127 int error; 128 int flags = 0; 129 130 fmp = (struct fdescmount *)mp->mnt_data; 131 if (mntflags & MNT_FORCE) { 132 /* The hash mutex protects the private mount flags. */ 133 mtx_lock(&fdesc_hashmtx); 134 fmp->flags |= FMNT_UNMOUNTF; 135 mtx_unlock(&fdesc_hashmtx); 136 flags |= FORCECLOSE; 137 } 138 139 /* 140 * Clear out buffer cache. I don't think we 141 * ever get anything cached at this level at the 142 * moment, but who knows... 143 * 144 * There is 1 extra root vnode reference corresponding 145 * to f_root. 146 */ 147 if ((error = vflush(mp, 1, flags, curthread)) != 0) 148 return (error); 149 150 /* 151 * Finally, throw away the fdescmount structure. Hold the hashmtx to 152 * protect the fdescmount structure. 153 */ 154 mtx_lock(&fdesc_hashmtx); 155 data = mp->mnt_data; 156 mp->mnt_data = NULL; 157 mtx_unlock(&fdesc_hashmtx); 158 free(data, M_FDESCMNT); /* XXX */ 159 160 return (0); 161 } 162 163 static int 164 fdesc_root(struct mount *mp, int flags, struct vnode **vpp) 165 { 166 struct vnode *vp; 167 168 /* 169 * Return locked reference to root. 170 */ 171 vp = VFSTOFDESC(mp)->f_root; 172 vget(vp, LK_EXCLUSIVE | LK_RETRY, curthread); 173 *vpp = vp; 174 return (0); 175 } 176 177 static int 178 fdesc_statfs(struct mount *mp, struct statfs *sbp) 179 { 180 struct thread *td; 181 struct filedesc *fdp; 182 int lim; 183 int i; 184 int last; 185 int freefd; 186 uint64_t limit; 187 188 td = curthread; 189 190 /* 191 * Compute number of free file descriptors. 192 * [ Strange results will ensue if the open file 193 * limit is ever reduced below the current number 194 * of open files... ] 195 */ 196 lim = lim_cur(td, RLIMIT_NOFILE); 197 fdp = td->td_proc->p_fd; 198 FILEDESC_SLOCK(fdp); 199 limit = racct_get_limit(td->td_proc, RACCT_NOFILE); 200 if (lim > limit) 201 lim = limit; 202 last = min(fdp->fd_nfiles, lim); 203 freefd = 0; 204 for (i = fdp->fd_freefile; i < last; i++) 205 if (fdp->fd_ofiles[i].fde_file == NULL) 206 freefd++; 207 208 /* 209 * Adjust for the fact that the fdesc array may not 210 * have been fully allocated yet. 211 */ 212 if (fdp->fd_nfiles < lim) 213 freefd += (lim - fdp->fd_nfiles); 214 FILEDESC_SUNLOCK(fdp); 215 216 sbp->f_flags = 0; 217 sbp->f_bsize = DEV_BSIZE; 218 sbp->f_iosize = DEV_BSIZE; 219 sbp->f_blocks = 2; /* 1K to keep df happy */ 220 sbp->f_bfree = 0; 221 sbp->f_bavail = 0; 222 sbp->f_files = lim + 1; /* Allow for "." */ 223 sbp->f_ffree = freefd; /* See comments above */ 224 return (0); 225 } 226 227 static struct vfsops fdesc_vfsops = { 228 .vfs_cmount = fdesc_cmount, 229 .vfs_init = fdesc_init, 230 .vfs_mount = fdesc_mount, 231 .vfs_root = fdesc_root, 232 .vfs_statfs = fdesc_statfs, 233 .vfs_uninit = fdesc_uninit, 234 .vfs_unmount = fdesc_unmount, 235 }; 236 237 VFS_SET(fdesc_vfsops, fdescfs, VFCF_SYNTHETIC | VFCF_JAIL); 238