fdesc_vfsops.c revision 246793
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 246793 2013-02-14 15:17:53Z bapt $ 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/racct.h> 51#include <sys/resourcevar.h> 52#include <sys/vnode.h> 53 54#include <fs/fdescfs/fdesc.h> 55 56static MALLOC_DEFINE(M_FDESCMNT, "fdesc_mount", "FDESC mount structure"); 57 58static vfs_cmount_t fdesc_cmount; 59static vfs_mount_t fdesc_mount; 60static vfs_unmount_t fdesc_unmount; 61static vfs_statfs_t fdesc_statfs; 62static vfs_root_t fdesc_root; 63 64/* 65 * Compatibility shim for old mount(2) system call. 66 */ 67int 68fdesc_cmount(struct mntarg *ma, void *data, uint64_t flags) 69{ 70 return kernel_mount(ma, flags); 71} 72 73/* 74 * Mount the per-process file descriptors (/dev/fd) 75 */ 76static int 77fdesc_mount(struct mount *mp) 78{ 79 int error = 0; 80 struct fdescmount *fmp; 81 struct vnode *rvp; 82 83 /* 84 * Update is a no-op 85 */ 86 if (mp->mnt_flag & (MNT_UPDATE | MNT_ROOTFS)) 87 return (EOPNOTSUPP); 88 89 fmp = malloc(sizeof(struct fdescmount), 90 M_FDESCMNT, M_WAITOK); /* XXX */ 91 92 /* 93 * We need to initialize a few bits of our local mount point struct to 94 * avoid confusion in allocvp. 95 */ 96 mp->mnt_data = (qaddr_t) fmp; 97 fmp->flags = 0; 98 error = fdesc_allocvp(Froot, -1, FD_ROOT, mp, &rvp); 99 if (error) { 100 free(fmp, M_FDESCMNT); 101 mp->mnt_data = NULL; 102 return (error); 103 } 104 rvp->v_type = VDIR; 105 rvp->v_vflag |= VV_ROOT; 106 fmp->f_root = rvp; 107 VOP_UNLOCK(rvp, 0); 108 /* XXX -- don't mark as local to work around fts() problems */ 109 /*mp->mnt_flag |= MNT_LOCAL;*/ 110 vfs_getnewfsid(mp); 111 112 vfs_mountedfrom(mp, "fdescfs"); 113 return (0); 114} 115 116static int 117fdesc_unmount(mp, mntflags) 118 struct mount *mp; 119 int mntflags; 120{ 121 struct fdescmount *fmp; 122 caddr_t data; 123 int error; 124 int flags = 0; 125 126 fmp = (struct fdescmount *)mp->mnt_data; 127 if (mntflags & MNT_FORCE) { 128 /* The hash mutex protects the private mount flags. */ 129 mtx_lock(&fdesc_hashmtx); 130 fmp->flags |= FMNT_UNMOUNTF; 131 mtx_unlock(&fdesc_hashmtx); 132 flags |= FORCECLOSE; 133 } 134 135 /* 136 * Clear out buffer cache. I don't think we 137 * ever get anything cached at this level at the 138 * moment, but who knows... 139 * 140 * There is 1 extra root vnode reference corresponding 141 * to f_root. 142 */ 143 if ((error = vflush(mp, 1, flags, curthread)) != 0) 144 return (error); 145 146 /* 147 * Finally, throw away the fdescmount structure. Hold the hashmtx to 148 * protect the fdescmount structure. 149 */ 150 mtx_lock(&fdesc_hashmtx); 151 data = mp->mnt_data; 152 mp->mnt_data = NULL; 153 mtx_unlock(&fdesc_hashmtx); 154 free(data, M_FDESCMNT); /* XXX */ 155 156 return (0); 157} 158 159static int 160fdesc_root(mp, flags, vpp) 161 struct mount *mp; 162 int flags; 163 struct vnode **vpp; 164{ 165 struct vnode *vp; 166 167 /* 168 * Return locked reference to root. 169 */ 170 vp = VFSTOFDESC(mp)->f_root; 171 vget(vp, LK_EXCLUSIVE | LK_RETRY, curthread); 172 *vpp = vp; 173 return (0); 174} 175 176static int 177fdesc_statfs(mp, sbp) 178 struct mount *mp; 179 struct statfs *sbp; 180{ 181 struct thread *td; 182 struct filedesc *fdp; 183 int lim; 184 int i; 185 int last; 186 int freefd; 187 uint64_t limit; 188 189 td = curthread; 190 191 /* 192 * Compute number of free file descriptors. 193 * [ Strange results will ensue if the open file 194 * limit is ever reduced below the current number 195 * of open files... ] 196 */ 197 PROC_LOCK(td->td_proc); 198 lim = lim_cur(td->td_proc, RLIMIT_NOFILE); 199 PROC_UNLOCK(td->td_proc); 200 fdp = td->td_proc->p_fd; 201 FILEDESC_SLOCK(fdp); 202 limit = racct_get_limit(td->td_proc, RACCT_NOFILE); 203 if (lim > limit) 204 lim = limit; 205 last = min(fdp->fd_nfiles, lim); 206 freefd = 0; 207 for (i = fdp->fd_freefile; i < last; i++) 208 if (fdp->fd_ofiles[i] == NULL) 209 freefd++; 210 211 /* 212 * Adjust for the fact that the fdesc array may not 213 * have been fully allocated yet. 214 */ 215 if (fdp->fd_nfiles < lim) 216 freefd += (lim - fdp->fd_nfiles); 217 FILEDESC_SUNLOCK(fdp); 218 219 sbp->f_flags = 0; 220 sbp->f_bsize = DEV_BSIZE; 221 sbp->f_iosize = DEV_BSIZE; 222 sbp->f_blocks = 2; /* 1K to keep df happy */ 223 sbp->f_bfree = 0; 224 sbp->f_bavail = 0; 225 sbp->f_files = lim + 1; /* Allow for "." */ 226 sbp->f_ffree = freefd; /* See comments above */ 227 return (0); 228} 229 230static struct vfsops fdesc_vfsops = { 231 .vfs_cmount = fdesc_cmount, 232 .vfs_init = fdesc_init, 233 .vfs_mount = fdesc_mount, 234 .vfs_root = fdesc_root, 235 .vfs_statfs = fdesc_statfs, 236 .vfs_uninit = fdesc_uninit, 237 .vfs_unmount = fdesc_unmount, 238}; 239 240VFS_SET(fdesc_vfsops, fdescfs, VFCF_SYNTHETIC); 241