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 * $FreeBSD$ 37 */ 38 39 /* 40 * /dev/fd Filesystem 41 */ 42 43 #include <sys/param.h> 44 #include <sys/systm.h> 45 #include <sys/filedesc.h> 46 #include <sys/kernel.h> 47 #include <sys/jail.h> 48 #include <sys/lock.h> 49 #include <sys/mutex.h> 50 #include <sys/malloc.h> 51 #include <sys/mount.h> 52 #include <sys/proc.h> 53 #include <sys/racct.h> 54 #include <sys/resourcevar.h> 55 #include <sys/vnode.h> 56 57 #include <fs/fdescfs/fdesc.h> 58 59 static MALLOC_DEFINE(M_FDESCMNT, "fdesc_mount", "FDESC mount structure"); 60 61 static vfs_cmount_t fdesc_cmount; 62 static vfs_mount_t fdesc_mount; 63 static vfs_unmount_t fdesc_unmount; 64 static vfs_statfs_t fdesc_statfs; 65 static vfs_root_t fdesc_root; 66 67 /* 68 * Compatibility shim for old mount(2) system call. 69 */ 70 int 71 fdesc_cmount(struct mntarg *ma, void *data, uint64_t flags) 72 { 73 74 return kernel_mount(ma, flags); 75 } 76 77 /* 78 * Mount the per-process file descriptors (/dev/fd) 79 */ 80 static int 81 fdesc_mount(struct mount *mp) 82 { 83 struct fdescmount *fmp; 84 struct vnode *rvp; 85 int error; 86 87 /* 88 * Update is a no-op 89 */ 90 if (mp->mnt_flag & (MNT_UPDATE | MNT_ROOTFS)) 91 return (EOPNOTSUPP); 92 93 fmp = malloc(sizeof(struct fdescmount), 94 M_FDESCMNT, M_WAITOK); /* XXX */ 95 96 /* 97 * We need to initialize a few bits of our local mount point struct to 98 * avoid confusion in allocvp. 99 */ 100 mp->mnt_data = fmp; 101 fmp->flags = 0; 102 if (vfs_getopt(mp->mnt_optnew, "linrdlnk", NULL, NULL) == 0) 103 fmp->flags |= FMNT_LINRDLNKF; 104 if (vfs_getopt(mp->mnt_optnew, "nodup", NULL, NULL) == 0) 105 fmp->flags |= FMNT_NODUP; 106 error = fdesc_allocvp(Froot, -1, FD_ROOT, mp, &rvp); 107 if (error) { 108 free(fmp, M_FDESCMNT); 109 mp->mnt_data = NULL; 110 return (error); 111 } 112 VN_LOCK_ASHARE(rvp); 113 rvp->v_type = VDIR; 114 rvp->v_vflag |= VV_ROOT; 115 fmp->f_root = rvp; 116 VOP_UNLOCK(rvp); 117 118 MNT_ILOCK(mp); 119 /* XXX -- don't mark as local to work around fts() problems */ 120 /*mp->mnt_flag |= MNT_LOCAL;*/ 121 /* 122 * Enable shared locking so that there is no contention on the root 123 * vnode. Note only root vnode enables shared locking for itself, 124 * so this end up being a nop for the rest. 125 */ 126 mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED | MNTK_EXTENDED_SHARED; 127 MNT_IUNLOCK(mp); 128 129 vfs_getnewfsid(mp); 130 131 vfs_mountedfrom(mp, "fdescfs"); 132 return (0); 133 } 134 135 static int 136 fdesc_unmount(struct mount *mp, int mntflags) 137 { 138 struct fdescmount *fmp; 139 int error, flags; 140 141 flags = 0; 142 fmp = mp->mnt_data; 143 if (mntflags & MNT_FORCE) { 144 /* The hash mutex protects the private mount flags. */ 145 mtx_lock(&fdesc_hashmtx); 146 fmp->flags |= FMNT_UNMOUNTF; 147 mtx_unlock(&fdesc_hashmtx); 148 flags |= FORCECLOSE; 149 } 150 151 /* 152 * Clear out buffer cache. I don't think we 153 * ever get anything cached at this level at the 154 * moment, but who knows... 155 * 156 * There is 1 extra root vnode reference corresponding 157 * to f_root. 158 */ 159 if ((error = vflush(mp, 1, flags, curthread)) != 0) 160 return (error); 161 162 /* 163 * Finally, throw away the fdescmount structure. 164 */ 165 mp->mnt_data = NULL; 166 free(fmp, M_FDESCMNT); 167 return (0); 168 } 169 170 static int 171 fdesc_root(struct mount *mp, int flags, struct vnode **vpp) 172 { 173 struct vnode *vp; 174 175 /* 176 * Return locked reference to root. 177 */ 178 vp = VFSTOFDESC(mp)->f_root; 179 vget(vp, flags | LK_RETRY); 180 *vpp = vp; 181 return (0); 182 } 183 184 static int 185 fdesc_statfs(struct mount *mp, struct statfs *sbp) 186 { 187 struct thread *td; 188 struct filedesc *fdp; 189 int lim; 190 int i; 191 int last; 192 int freefd; 193 uint64_t limit; 194 195 td = curthread; 196 197 /* 198 * Compute number of free file descriptors. 199 * [ Strange results will ensue if the open file 200 * limit is ever reduced below the current number 201 * of open files... ] 202 */ 203 lim = lim_cur(td, RLIMIT_NOFILE); 204 fdp = td->td_proc->p_fd; 205 FILEDESC_SLOCK(fdp); 206 limit = racct_get_limit(td->td_proc, RACCT_NOFILE); 207 if (lim > limit) 208 lim = limit; 209 last = min(fdp->fd_nfiles, lim); 210 freefd = 0; 211 for (i = fdp->fd_freefile; i < last; i++) 212 if (fdp->fd_ofiles[i].fde_file == NULL) 213 freefd++; 214 215 /* 216 * Adjust for the fact that the fdesc array may not 217 * have been fully allocated yet. 218 */ 219 if (fdp->fd_nfiles < lim) 220 freefd += (lim - fdp->fd_nfiles); 221 FILEDESC_SUNLOCK(fdp); 222 223 sbp->f_flags = 0; 224 sbp->f_bsize = DEV_BSIZE; 225 sbp->f_iosize = DEV_BSIZE; 226 sbp->f_blocks = 2; /* 1K to keep df happy */ 227 sbp->f_bfree = 0; 228 sbp->f_bavail = 0; 229 sbp->f_files = lim + 1; /* Allow for "." */ 230 sbp->f_ffree = freefd; /* See comments above */ 231 return (0); 232 } 233 234 static struct vfsops fdesc_vfsops = { 235 .vfs_cmount = fdesc_cmount, 236 .vfs_init = fdesc_init, 237 .vfs_mount = fdesc_mount, 238 .vfs_root = fdesc_root, 239 .vfs_statfs = fdesc_statfs, 240 .vfs_uninit = fdesc_uninit, 241 .vfs_unmount = fdesc_unmount, 242 }; 243 244 VFS_SET(fdesc_vfsops, fdescfs, VFCF_SYNTHETIC | VFCF_JAIL); 245