fdesc_vfsops.c revision 137478
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 137478 2004-11-09 22:14:57Z phk $ 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_mount_t fdesc_mount; 58static vfs_unmount_t fdesc_unmount; 59static vfs_statfs_t fdesc_statfs; 60 61/* 62 * Mount the per-process file descriptors (/dev/fd) 63 */ 64static int 65fdesc_mount(struct mount *mp, struct thread *td) 66{ 67 int error = 0; 68 struct fdescmount *fmp; 69 struct vnode *rvp; 70 71 /* 72 * Update is a no-op 73 */ 74 if (mp->mnt_flag & (MNT_UPDATE | MNT_ROOTFS)) 75 return (EOPNOTSUPP); 76 77 error = fdesc_allocvp(Froot, FD_ROOT, mp, &rvp, td); 78 if (error) 79 return (error); 80 81 MALLOC(fmp, struct fdescmount *, sizeof(struct fdescmount), 82 M_FDESCMNT, M_WAITOK); /* XXX */ 83 rvp->v_type = VDIR; 84 rvp->v_vflag |= VV_ROOT; 85 fmp->f_root = rvp; 86 /* XXX -- don't mark as local to work around fts() problems */ 87 /*mp->mnt_flag |= MNT_LOCAL;*/ 88 mp->mnt_data = (qaddr_t) fmp; 89 vfs_getnewfsid(mp); 90 91 bzero(mp->mnt_stat.f_mntfromname, MNAMELEN); 92 bcopy("fdescfs", mp->mnt_stat.f_mntfromname, sizeof("fdescfs")); 93 (void)fdesc_statfs(mp, &mp->mnt_stat, td); 94 return (0); 95} 96 97static int 98fdesc_unmount(mp, mntflags, td) 99 struct mount *mp; 100 int mntflags; 101 struct thread *td; 102{ 103 int error; 104 int flags = 0; 105 106 if (mntflags & MNT_FORCE) 107 flags |= FORCECLOSE; 108 109 /* 110 * Clear out buffer cache. I don't think we 111 * ever get anything cached at this level at the 112 * moment, but who knows... 113 * 114 * There is 1 extra root vnode reference corresponding 115 * to f_root. 116 */ 117 if ((error = vflush(mp, 1, flags, td)) != 0) 118 return (error); 119 120 /* 121 * Finally, throw away the fdescmount structure 122 */ 123 free(mp->mnt_data, M_FDESCMNT); /* XXX */ 124 mp->mnt_data = 0; 125 126 return (0); 127} 128 129int 130fdesc_root(mp, vpp, td) 131 struct mount *mp; 132 struct vnode **vpp; 133 struct thread *td; 134{ 135 struct vnode *vp; 136 137 /* 138 * Return locked reference to root. 139 */ 140 vp = VFSTOFDESC(mp)->f_root; 141 VREF(vp); 142 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); 143 *vpp = vp; 144 return (0); 145} 146 147static int 148fdesc_statfs(mp, sbp, td) 149 struct mount *mp; 150 struct statfs *sbp; 151 struct thread *td; 152{ 153 struct filedesc *fdp; 154 int lim; 155 int i; 156 int last; 157 int freefd; 158 159 /* 160 * Compute number of free file descriptors. 161 * [ Strange results will ensue if the open file 162 * limit is ever reduced below the current number 163 * of open files... ] 164 */ 165 PROC_LOCK(td->td_proc); 166 lim = lim_cur(td->td_proc, RLIMIT_NOFILE); 167 PROC_UNLOCK(td->td_proc); 168 fdp = td->td_proc->p_fd; 169 FILEDESC_LOCK(fdp); 170 last = min(fdp->fd_nfiles, lim); 171 freefd = 0; 172 for (i = fdp->fd_freefile; i < last; i++) 173 if (fdp->fd_ofiles[i] == NULL) 174 freefd++; 175 176 /* 177 * Adjust for the fact that the fdesc array may not 178 * have been fully allocated yet. 179 */ 180 if (fdp->fd_nfiles < lim) 181 freefd += (lim - fdp->fd_nfiles); 182 FILEDESC_UNLOCK(fdp); 183 184 sbp->f_flags = 0; 185 sbp->f_bsize = DEV_BSIZE; 186 sbp->f_iosize = DEV_BSIZE; 187 sbp->f_blocks = 2; /* 1K to keep df happy */ 188 sbp->f_bfree = 0; 189 sbp->f_bavail = 0; 190 sbp->f_files = lim + 1; /* Allow for "." */ 191 sbp->f_ffree = freefd; /* See comments above */ 192 if (sbp != &mp->mnt_stat) { 193 sbp->f_type = mp->mnt_vfc->vfc_typenum; 194 bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid)); 195 bcopy(mp->mnt_stat.f_mntonname, sbp->f_mntonname, MNAMELEN); 196 bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN); 197 } 198 return (0); 199} 200 201static struct vfsops fdesc_vfsops = { 202 .vfs_init = fdesc_init, 203 .vfs_mount = fdesc_mount, 204 .vfs_root = fdesc_root, 205 .vfs_statfs = fdesc_statfs, 206 .vfs_unmount = fdesc_unmount, 207}; 208 209VFS_SET(fdesc_vfsops, fdescfs, VFCF_SYNTHETIC); 210