null_vfsops.c revision 139776
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 139776 2005-01-06 18:10:42Z imp $ 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/kdb.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_checkexp_t nullfs_checkexp; 60static vfs_mount_t nullfs_mount; 61static vfs_quotactl_t nullfs_quotactl; 62static vfs_root_t nullfs_root; 63static vfs_sync_t nullfs_sync; 64static vfs_statfs_t nullfs_statfs; 65static vfs_unmount_t nullfs_unmount; 66static vfs_vget_t nullfs_vget; 67static vfs_vptofh_t nullfs_vptofh; 68static vfs_extattrctl_t nullfs_extattrctl; 69 70/* 71 * Mount null layer 72 */ 73static int 74nullfs_mount(struct mount *mp, struct thread *td) 75{ 76 int error = 0; 77 struct vnode *lowerrootvp, *vp; 78 struct vnode *nullm_rootvp; 79 struct null_mount *xmp; 80 char *target; 81 int isvnunlocked = 0, len; 82 struct nameidata nd, *ndp = &nd; 83 84 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp); 85 86 if (mp->mnt_flag & MNT_ROOTFS) 87 return (EOPNOTSUPP); 88 /* 89 * Update is a no-op 90 */ 91 if (mp->mnt_flag & MNT_UPDATE) { 92 return (EOPNOTSUPP); 93 /* return VFS_MOUNT(MOUNTTONULLMOUNT(mp)->nullm_vfs, path, data, ndp, td);*/ 94 } 95 96 /* 97 * Get argument 98 */ 99 error = vfs_getopt(mp->mnt_optnew, "target", (void **)&target, &len); 100 if (error || target[len - 1] != '\0') 101 return (EINVAL); 102 103 /* 104 * Unlock lower node to avoid deadlock. 105 * (XXX) VOP_ISLOCKED is needed? 106 */ 107 if ((mp->mnt_vnodecovered->v_op == &null_vnodeops) && 108 VOP_ISLOCKED(mp->mnt_vnodecovered, NULL)) { 109 VOP_UNLOCK(mp->mnt_vnodecovered, 0, td); 110 isvnunlocked = 1; 111 } 112 /* 113 * Find lower node 114 */ 115 NDINIT(ndp, LOOKUP, FOLLOW|WANTPARENT|LOCKLEAF, 116 UIO_SYSSPACE, target, td); 117 error = namei(ndp); 118 /* 119 * Re-lock vnode. 120 */ 121 if (isvnunlocked && !VOP_ISLOCKED(mp->mnt_vnodecovered, NULL)) 122 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY, td); 123 124 if (error) 125 return (error); 126 NDFREE(ndp, NDF_ONLY_PNBUF); 127 128 /* 129 * Sanity check on lower vnode 130 */ 131 lowerrootvp = ndp->ni_vp; 132 133 vrele(ndp->ni_dvp); 134 ndp->ni_dvp = NULLVP; 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, td); 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, td); 180 181 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) 182 mp->mnt_flag |= MNT_LOCAL; 183 mp->mnt_data = (qaddr_t) xmp; 184 vfs_getnewfsid(mp); 185 186 vfs_mountedfrom(mp, target); 187 188 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 189 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 190 return (0); 191} 192 193/* 194 * Free reference to null layer 195 */ 196static int 197nullfs_unmount(mp, mntflags, td) 198 struct mount *mp; 199 int mntflags; 200 struct thread *td; 201{ 202 void *mntdata; 203 int error; 204 int flags = 0; 205 206 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 207 208 if (mntflags & MNT_FORCE) 209 flags |= FORCECLOSE; 210 211 /* There is 1 extra root vnode reference (nullm_rootvp). */ 212 error = vflush(mp, 1, flags, td); 213 if (error) 214 return (error); 215 216 /* 217 * Finally, throw away the null_mount structure 218 */ 219 mntdata = mp->mnt_data; 220 mp->mnt_data = 0; 221 free(mntdata, M_NULLFSMNT); 222 return 0; 223} 224 225static int 226nullfs_root(mp, vpp, td) 227 struct mount *mp; 228 struct vnode **vpp; 229 struct thread *td; 230{ 231 struct vnode *vp; 232 233 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp, 234 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 235 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 236 237 /* 238 * Return locked reference to root. 239 */ 240 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 241 VREF(vp); 242 243#ifdef NULLFS_DEBUG 244 if (VOP_ISLOCKED(vp, NULL)) { 245 kdb_enter("root vnode is locked.\n"); 246 vrele(vp); 247 return (EDEADLK); 248 } 249#endif 250 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); 251 *vpp = vp; 252 return 0; 253} 254 255static int 256nullfs_quotactl(mp, cmd, uid, arg, td) 257 struct mount *mp; 258 int cmd; 259 uid_t uid; 260 caddr_t arg; 261 struct thread *td; 262{ 263 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, td); 264} 265 266static int 267nullfs_statfs(mp, sbp, td) 268 struct mount *mp; 269 struct statfs *sbp; 270 struct thread *td; 271{ 272 int error; 273 struct statfs mstat; 274 275 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 276 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 277 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 278 279 bzero(&mstat, sizeof(mstat)); 280 281 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, td); 282 if (error) 283 return (error); 284 285 /* now copy across the "interesting" information and fake the rest */ 286 sbp->f_type = mstat.f_type; 287 sbp->f_flags = mstat.f_flags; 288 sbp->f_bsize = mstat.f_bsize; 289 sbp->f_iosize = mstat.f_iosize; 290 sbp->f_blocks = mstat.f_blocks; 291 sbp->f_bfree = mstat.f_bfree; 292 sbp->f_bavail = mstat.f_bavail; 293 sbp->f_files = mstat.f_files; 294 sbp->f_ffree = mstat.f_ffree; 295 return (0); 296} 297 298static int 299nullfs_sync(mp, waitfor, cred, td) 300 struct mount *mp; 301 int waitfor; 302 struct ucred *cred; 303 struct thread *td; 304{ 305 /* 306 * XXX - Assumes no data cached at null layer. 307 */ 308 return (0); 309} 310 311static int 312nullfs_vget(mp, ino, flags, vpp) 313 struct mount *mp; 314 ino_t ino; 315 int flags; 316 struct vnode **vpp; 317{ 318 int error; 319 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp); 320 if (error) 321 return (error); 322 323 return (null_nodeget(mp, *vpp, vpp)); 324} 325 326static int 327nullfs_fhtovp(mp, fidp, vpp) 328 struct mount *mp; 329 struct fid *fidp; 330 struct vnode **vpp; 331{ 332 int error; 333 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, vpp); 334 if (error) 335 return (error); 336 337 return (null_nodeget(mp, *vpp, vpp)); 338} 339 340static int 341nullfs_checkexp(mp, nam, extflagsp, credanonp) 342 struct mount *mp; 343 struct sockaddr *nam; 344 int *extflagsp; 345 struct ucred **credanonp; 346{ 347 348 return VFS_CHECKEXP(MOUNTTONULLMOUNT(mp)->nullm_vfs, nam, 349 extflagsp, credanonp); 350} 351 352static int 353nullfs_vptofh(vp, fhp) 354 struct vnode *vp; 355 struct fid *fhp; 356{ 357 struct vnode *lvp; 358 359 lvp = NULLVPTOLOWERVP(vp); 360 return VFS_VPTOFH(lvp, fhp); 361} 362 363static int 364nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname, td) 365 struct mount *mp; 366 int cmd; 367 struct vnode *filename_vp; 368 int namespace; 369 const char *attrname; 370 struct thread *td; 371{ 372 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, filename_vp, 373 namespace, attrname, td); 374} 375 376 377static struct vfsops null_vfsops = { 378 .vfs_checkexp = nullfs_checkexp, 379 .vfs_extattrctl = nullfs_extattrctl, 380 .vfs_fhtovp = nullfs_fhtovp, 381 .vfs_init = nullfs_init, 382 .vfs_mount = nullfs_mount, 383 .vfs_quotactl = nullfs_quotactl, 384 .vfs_root = nullfs_root, 385 .vfs_statfs = nullfs_statfs, 386 .vfs_sync = nullfs_sync, 387 .vfs_uninit = nullfs_uninit, 388 .vfs_unmount = nullfs_unmount, 389 .vfs_vget = nullfs_vget, 390 .vfs_vptofh = nullfs_vptofh, 391}; 392 393VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK); 394