fdesc_vfsops.c revision 172697
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: head/sys/fs/fdescfs/fdesc_vfsops.c 172697 2007-10-16 10:54:55Z alfred $ 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 55static MALLOC_DEFINE(M_FDESCMNT, "fdesc_mount", "FDESC mount structure"); 56 57static vfs_cmount_t fdesc_cmount; 58static vfs_mount_t fdesc_mount; 59static vfs_unmount_t fdesc_unmount; 60static vfs_statfs_t fdesc_statfs; 61static vfs_root_t fdesc_root; 62 63/* 64 * Compatibility shim for old mount(2) system call. 65 */ 66int 67fdesc_cmount(struct mntarg *ma, void *data, int flags, struct thread *td) 68{ 69 return kernel_mount(ma, flags); 70} 71 72/* 73 * Mount the per-process file descriptors (/dev/fd) 74 */ 75static int 76fdesc_mount(struct mount *mp, struct thread *td) 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 error = fdesc_allocvp(Froot, FD_ROOT, mp, &rvp, td); 89 if (error) 90 return (error); 91 92 MALLOC(fmp, struct fdescmount *, sizeof(struct fdescmount), 93 M_FDESCMNT, M_WAITOK); /* XXX */ 94 rvp->v_type = VDIR; 95 rvp->v_vflag |= VV_ROOT; 96 fmp->f_root = rvp; 97 /* XXX -- don't mark as local to work around fts() problems */ 98 /*mp->mnt_flag |= MNT_LOCAL;*/ 99 mp->mnt_data = fmp; 100 vfs_getnewfsid(mp); 101 102 vfs_mountedfrom(mp, "fdescfs"); 103 return (0); 104} 105 106static int 107fdesc_unmount(mp, mntflags, td) 108 struct mount *mp; 109 int mntflags; 110 struct thread *td; 111{ 112 int error; 113 int flags = 0; 114 115 if (mntflags & MNT_FORCE) 116 flags |= FORCECLOSE; 117 118 /* 119 * Clear out buffer cache. I don't think we 120 * ever get anything cached at this level at the 121 * moment, but who knows... 122 * 123 * There is 1 extra root vnode reference corresponding 124 * to f_root. 125 */ 126 if ((error = vflush(mp, 1, flags, td)) != 0) 127 return (error); 128 129 /* 130 * Finally, throw away the fdescmount structure 131 */ 132 free(mp->mnt_data, M_FDESCMNT); /* XXX */ 133 mp->mnt_data = 0; 134 135 return (0); 136} 137 138static int 139fdesc_root(mp, flags, vpp, td) 140 struct mount *mp; 141 int flags; 142 struct vnode **vpp; 143 struct thread *td; 144{ 145 struct vnode *vp; 146 147 /* 148 * Return locked reference to root. 149 */ 150 vp = VFSTOFDESC(mp)->f_root; 151 VREF(vp); 152 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); 153 *vpp = vp; 154 return (0); 155} 156 157static int 158fdesc_statfs(mp, sbp, td) 159 struct mount *mp; 160 struct statfs *sbp; 161 struct thread *td; 162{ 163 struct filedesc *fdp; 164 int lim; 165 int i; 166 int last; 167 int freefd; 168 169 /* 170 * Compute number of free file descriptors. 171 * [ Strange results will ensue if the open file 172 * limit is ever reduced below the current number 173 * of open files... ] 174 */ 175 PROC_LOCK(td->td_proc); 176 lim = lim_cur(td->td_proc, RLIMIT_NOFILE); 177 PROC_UNLOCK(td->td_proc); 178 fdp = td->td_proc->p_fd; 179 FILEDESC_SLOCK(fdp); 180 last = min(fdp->fd_nfiles, lim); 181 freefd = 0; 182 for (i = fdp->fd_freefile; i < last; i++) 183 if (fdp->fd_ofiles[i] == NULL) 184 freefd++; 185 186 /* 187 * Adjust for the fact that the fdesc array may not 188 * have been fully allocated yet. 189 */ 190 if (fdp->fd_nfiles < lim) 191 freefd += (lim - fdp->fd_nfiles); 192 FILEDESC_SUNLOCK(fdp); 193 194 sbp->f_flags = 0; 195 sbp->f_bsize = DEV_BSIZE; 196 sbp->f_iosize = DEV_BSIZE; 197 sbp->f_blocks = 2; /* 1K to keep df happy */ 198 sbp->f_bfree = 0; 199 sbp->f_bavail = 0; 200 sbp->f_files = lim + 1; /* Allow for "." */ 201 sbp->f_ffree = freefd; /* See comments above */ 202 return (0); 203} 204 205static struct vfsops fdesc_vfsops = { 206 .vfs_cmount = fdesc_cmount, 207 .vfs_init = fdesc_init, 208 .vfs_mount = fdesc_mount, 209 .vfs_root = fdesc_root, 210 .vfs_statfs = fdesc_statfs, 211 .vfs_unmount = fdesc_unmount, 212}; 213 214VFS_SET(fdesc_vfsops, fdescfs, VFCF_SYNTHETIC); 215