1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1992, 1993, 1995 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software donated to Berkeley by 8 * Jan-Simon Pendry. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)fdesc_vfsops.c 8.4 (Berkeley) 1/21/94 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 vnode *rvp; 83 int error; 84 85 /* 86 * Update is a no-op 87 */ 88 if (mp->mnt_flag & (MNT_UPDATE | MNT_ROOTFS)) 89 return (EOPNOTSUPP); 90 91 fmp = malloc(sizeof(struct fdescmount), M_FDESCMNT, M_WAITOK); 92 93 /* 94 * We need to initialize a few bits of our local mount point struct to 95 * avoid confusion in allocvp. 96 */ 97 mp->mnt_data = fmp; 98 fmp->flags = 0; 99 if (vfs_getopt(mp->mnt_optnew, "linrdlnk", NULL, NULL) == 0) 100 fmp->flags |= FMNT_LINRDLNKF; 101 if (vfs_getopt(mp->mnt_optnew, "rdlnk", NULL, NULL) == 0) 102 fmp->flags |= FMNT_RDLNKF; 103 if (vfs_getopt(mp->mnt_optnew, "nodup", NULL, NULL) == 0) 104 fmp->flags |= FMNT_NODUP; 105 error = fdesc_allocvp(Froot, -1, FD_ROOT, mp, &rvp); 106 if (error) { 107 free(fmp, M_FDESCMNT); 108 mp->mnt_data = NULL; 109 return (error); 110 } 111 VN_LOCK_ASHARE(rvp); 112 rvp->v_type = VDIR; 113 rvp->v_vflag |= VV_ROOT; 114 fmp->f_root = rvp; 115 VOP_UNLOCK(rvp); 116 117 MNT_ILOCK(mp); 118 /* XXX -- don't mark as local to work around fts() problems */ 119 /*mp->mnt_flag |= MNT_LOCAL;*/ 120 /* 121 * Enable shared locking so that there is no contention on the root 122 * vnode. Note only root vnode enables shared locking for itself, 123 * so this end up being a nop for the rest. 124 */ 125 mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED | MNTK_EXTENDED_SHARED; 126 MNT_IUNLOCK(mp); 127 128 vfs_getnewfsid(mp); 129 130 vfs_mountedfrom(mp, "fdescfs"); 131 return (0); 132 } 133 134 static int 135 fdesc_unmount(struct mount *mp, int mntflags) 136 { 137 struct fdescmount *fmp; 138 int error, flags; 139 140 flags = 0; 141 fmp = mp->mnt_data; 142 if (mntflags & MNT_FORCE) { 143 /* The hash mutex protects the private mount flags. */ 144 mtx_lock(&fdesc_hashmtx); 145 fmp->flags |= FMNT_UNMOUNTF; 146 mtx_unlock(&fdesc_hashmtx); 147 flags |= FORCECLOSE; 148 } 149 150 /* 151 * Clear out buffer cache. I don't think we 152 * ever get anything cached at this level at the 153 * moment, but who knows... 154 * 155 * There is 1 extra root vnode reference corresponding 156 * to f_root. 157 */ 158 if ((error = vflush(mp, 1, flags, curthread)) != 0) 159 return (error); 160 161 /* 162 * Finally, throw away the fdescmount structure. 163 */ 164 mp->mnt_data = NULL; 165 free(fmp, M_FDESCMNT); 166 return (0); 167 } 168 169 static int 170 fdesc_root(struct mount *mp, int flags, struct vnode **vpp) 171 { 172 struct vnode *vp; 173 174 /* 175 * Return locked reference to root. 176 */ 177 vp = VFSTOFDESC(mp)->f_root; 178 vget(vp, flags | LK_RETRY); 179 *vpp = vp; 180 return (0); 181 } 182 183 static int 184 fdesc_statfs(struct mount *mp, struct statfs *sbp) 185 { 186 struct thread *td; 187 struct filedesc *fdp; 188 int lim; 189 int i; 190 int last; 191 int freefd; 192 uint64_t limit; 193 194 td = curthread; 195 196 /* 197 * Compute number of free file descriptors. 198 * [ Strange results will ensue if the open file 199 * limit is ever reduced below the current number 200 * of open files... ] 201 */ 202 lim = lim_cur(td, RLIMIT_NOFILE); 203 fdp = td->td_proc->p_fd; 204 FILEDESC_SLOCK(fdp); 205 limit = racct_get_limit(td->td_proc, RACCT_NOFILE); 206 if (lim > limit) 207 lim = limit; 208 last = min(fdp->fd_nfiles, lim); 209 freefd = 0; 210 for (i = fdp->fd_freefile; i < last; i++) 211 if (fdp->fd_ofiles[i].fde_file == NULL) 212 freefd++; 213 214 /* 215 * Adjust for the fact that the fdesc array may not 216 * have been fully allocated yet. 217 */ 218 if (fdp->fd_nfiles < lim) 219 freefd += (lim - fdp->fd_nfiles); 220 FILEDESC_SUNLOCK(fdp); 221 222 sbp->f_flags = 0; 223 sbp->f_bsize = DEV_BSIZE; 224 sbp->f_iosize = DEV_BSIZE; 225 sbp->f_blocks = 2; /* 1K to keep df happy */ 226 sbp->f_bfree = 2; 227 sbp->f_bavail = 2; 228 sbp->f_files = lim + 1; /* Allow for "." */ 229 sbp->f_ffree = freefd; /* See comments above */ 230 return (0); 231 } 232 233 static struct vfsops fdesc_vfsops = { 234 .vfs_cmount = fdesc_cmount, 235 .vfs_init = fdesc_init, 236 .vfs_mount = fdesc_mount, 237 .vfs_root = fdesc_root, 238 .vfs_statfs = fdesc_statfs, 239 .vfs_uninit = fdesc_uninit, 240 .vfs_unmount = fdesc_unmount, 241 }; 242 243 VFS_SET(fdesc_vfsops, fdescfs, VFCF_SYNTHETIC | VFCF_JAIL); 244