null_vfsops.c revision 177785
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 * @(#)null_vfsops.c 8.2 (Berkeley) 1/21/94 33 * 34 * @(#)lofs_vfsops.c 1.2 (Berkeley) 6/18/92 35 * $FreeBSD: head/sys/fs/nullfs/null_vfsops.c 177785 2008-03-31 12:01:21Z kib $ 36 */ 37 38/* 39 * Null Layer 40 * (See null_vnops.c for a description of what this does.) 41 */ 42 43#include <sys/param.h> 44#include <sys/systm.h> 45#include <sys/fcntl.h> 46#include <sys/kernel.h> 47#include <sys/lock.h> 48#include <sys/malloc.h> 49#include <sys/mount.h> 50#include <sys/namei.h> 51#include <sys/proc.h> 52#include <sys/vnode.h> 53 54#include <fs/nullfs/null.h> 55 56static MALLOC_DEFINE(M_NULLFSMNT, "nullfs_mount", "NULLFS mount structure"); 57 58static vfs_fhtovp_t nullfs_fhtovp; 59static vfs_mount_t nullfs_mount; 60static vfs_quotactl_t nullfs_quotactl; 61static vfs_root_t nullfs_root; 62static vfs_sync_t nullfs_sync; 63static vfs_statfs_t nullfs_statfs; 64static vfs_unmount_t nullfs_unmount; 65static vfs_vget_t nullfs_vget; 66static vfs_extattrctl_t nullfs_extattrctl; 67 68/* 69 * Mount null layer 70 */ 71static int 72nullfs_mount(struct mount *mp, struct thread *td) 73{ 74 int error = 0; 75 struct vnode *lowerrootvp, *vp; 76 struct vnode *nullm_rootvp; 77 struct null_mount *xmp; 78 char *target; 79 int isvnunlocked = 0, len; 80 struct nameidata nd, *ndp = &nd; 81 82 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp); 83 84 if (mp->mnt_flag & MNT_ROOTFS) 85 return (EOPNOTSUPP); 86 /* 87 * Update is a no-op 88 */ 89 if (mp->mnt_flag & MNT_UPDATE) { 90 /* 91 * Only support update mounts for NFS export. 92 */ 93 if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0)) 94 return (0); 95 else 96 return (EOPNOTSUPP); 97 } 98 99 /* 100 * Get argument 101 */ 102 error = vfs_getopt(mp->mnt_optnew, "target", (void **)&target, &len); 103 if (error || target[len - 1] != '\0') 104 return (EINVAL); 105 106 /* 107 * Unlock lower node to avoid deadlock. 108 * (XXX) VOP_ISLOCKED is needed? 109 */ 110 if ((mp->mnt_vnodecovered->v_op == &null_vnodeops) && 111 VOP_ISLOCKED(mp->mnt_vnodecovered)) { 112 VOP_UNLOCK(mp->mnt_vnodecovered, 0); 113 isvnunlocked = 1; 114 } 115 /* 116 * Find lower node 117 */ 118 NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF, 119 UIO_SYSSPACE, target, td); 120 error = namei(ndp); 121 /* 122 * Re-lock vnode. 123 */ 124 if (isvnunlocked && !VOP_ISLOCKED(mp->mnt_vnodecovered)) 125 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY); 126 127 if (error) 128 return (error); 129 NDFREE(ndp, NDF_ONLY_PNBUF); 130 131 /* 132 * Sanity check on lower vnode 133 */ 134 lowerrootvp = ndp->ni_vp; 135 136 /* 137 * Check multi null mount to avoid `lock against myself' panic. 138 */ 139 if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) { 140 NULLFSDEBUG("nullfs_mount: multi null mount?\n"); 141 vput(lowerrootvp); 142 return (EDEADLK); 143 } 144 145 xmp = (struct null_mount *) malloc(sizeof(struct null_mount), 146 M_NULLFSMNT, M_WAITOK); /* XXX */ 147 148 /* 149 * Save reference to underlying FS 150 */ 151 xmp->nullm_vfs = lowerrootvp->v_mount; 152 153 /* 154 * Save reference. Each mount also holds 155 * a reference on the root vnode. 156 */ 157 error = null_nodeget(mp, lowerrootvp, &vp); 158 /* 159 * Make sure the node alias worked 160 */ 161 if (error) { 162 VOP_UNLOCK(vp, 0); 163 vrele(lowerrootvp); 164 free(xmp, M_NULLFSMNT); /* XXX */ 165 return (error); 166 } 167 168 /* 169 * Keep a held reference to the root vnode. 170 * It is vrele'd in nullfs_unmount. 171 */ 172 nullm_rootvp = vp; 173 nullm_rootvp->v_vflag |= VV_ROOT; 174 xmp->nullm_rootvp = nullm_rootvp; 175 176 /* 177 * Unlock the node (either the lower or the alias) 178 */ 179 VOP_UNLOCK(vp, 0); 180 181 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) { 182 MNT_ILOCK(mp); 183 mp->mnt_flag |= MNT_LOCAL; 184 MNT_IUNLOCK(mp); 185 } 186 MNT_ILOCK(mp); 187 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & MNTK_MPSAFE; 188 MNT_IUNLOCK(mp); 189 mp->mnt_data = xmp; 190 vfs_getnewfsid(mp); 191 192 vfs_mountedfrom(mp, target); 193 194 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 195 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 196 return (0); 197} 198 199/* 200 * Free reference to null layer 201 */ 202static int 203nullfs_unmount(mp, mntflags, td) 204 struct mount *mp; 205 int mntflags; 206 struct thread *td; 207{ 208 void *mntdata; 209 int error; 210 int flags = 0; 211 212 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 213 214 if (mntflags & MNT_FORCE) 215 flags |= FORCECLOSE; 216 217 /* There is 1 extra root vnode reference (nullm_rootvp). */ 218 error = vflush(mp, 1, flags, td); 219 if (error) 220 return (error); 221 222 /* 223 * Finally, throw away the null_mount structure 224 */ 225 mntdata = mp->mnt_data; 226 mp->mnt_data = 0; 227 free(mntdata, M_NULLFSMNT); 228 return 0; 229} 230 231static int 232nullfs_root(mp, flags, vpp, td) 233 struct mount *mp; 234 int flags; 235 struct vnode **vpp; 236 struct thread *td; 237{ 238 struct vnode *vp; 239 240 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp, 241 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 242 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 243 244 /* 245 * Return locked reference to root. 246 */ 247 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 248 VREF(vp); 249 250#ifdef NULLFS_DEBUG 251 if (VOP_ISLOCKED(vp)) 252 panic("root vnode is locked.\n"); 253#endif 254 vn_lock(vp, flags | LK_RETRY); 255 *vpp = vp; 256 return 0; 257} 258 259static int 260nullfs_quotactl(mp, cmd, uid, arg, td) 261 struct mount *mp; 262 int cmd; 263 uid_t uid; 264 void *arg; 265 struct thread *td; 266{ 267 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, td); 268} 269 270static int 271nullfs_statfs(mp, sbp, td) 272 struct mount *mp; 273 struct statfs *sbp; 274 struct thread *td; 275{ 276 int error; 277 struct statfs mstat; 278 279 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 280 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 281 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 282 283 bzero(&mstat, sizeof(mstat)); 284 285 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, td); 286 if (error) 287 return (error); 288 289 /* now copy across the "interesting" information and fake the rest */ 290 sbp->f_type = mstat.f_type; 291 sbp->f_flags = mstat.f_flags; 292 sbp->f_bsize = mstat.f_bsize; 293 sbp->f_iosize = mstat.f_iosize; 294 sbp->f_blocks = mstat.f_blocks; 295 sbp->f_bfree = mstat.f_bfree; 296 sbp->f_bavail = mstat.f_bavail; 297 sbp->f_files = mstat.f_files; 298 sbp->f_ffree = mstat.f_ffree; 299 return (0); 300} 301 302static int 303nullfs_sync(mp, waitfor, td) 304 struct mount *mp; 305 int waitfor; 306 struct thread *td; 307{ 308 /* 309 * XXX - Assumes no data cached at null layer. 310 */ 311 return (0); 312} 313 314static int 315nullfs_vget(mp, ino, flags, vpp) 316 struct mount *mp; 317 ino_t ino; 318 int flags; 319 struct vnode **vpp; 320{ 321 int error; 322 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp); 323 if (error) 324 return (error); 325 326 return (null_nodeget(mp, *vpp, vpp)); 327} 328 329static int 330nullfs_fhtovp(mp, fidp, vpp) 331 struct mount *mp; 332 struct fid *fidp; 333 struct vnode **vpp; 334{ 335 int error; 336 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, vpp); 337 if (error) 338 return (error); 339 340 return (null_nodeget(mp, *vpp, vpp)); 341} 342 343static int 344nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname, td) 345 struct mount *mp; 346 int cmd; 347 struct vnode *filename_vp; 348 int namespace; 349 const char *attrname; 350 struct thread *td; 351{ 352 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, filename_vp, 353 namespace, attrname, td); 354} 355 356 357static struct vfsops null_vfsops = { 358 .vfs_extattrctl = nullfs_extattrctl, 359 .vfs_fhtovp = nullfs_fhtovp, 360 .vfs_init = nullfs_init, 361 .vfs_mount = nullfs_mount, 362 .vfs_quotactl = nullfs_quotactl, 363 .vfs_root = nullfs_root, 364 .vfs_statfs = nullfs_statfs, 365 .vfs_sync = nullfs_sync, 366 .vfs_uninit = nullfs_uninit, 367 .vfs_unmount = nullfs_unmount, 368 .vfs_vget = nullfs_vget, 369}; 370 371VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK); 372