1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1992, 1993, 1995 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software donated to Berkeley by 8 * Jan-Simon Pendry. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * @(#)null_vfsops.c 8.2 (Berkeley) 1/21/94 35 * 36 * @(#)lofs_vfsops.c 1.2 (Berkeley) 6/18/92 37 * $FreeBSD$ 38 */ 39 40 /* 41 * Null Layer 42 * (See null_vnops.c for a description of what this does.) 43 */ 44 45 #include <sys/param.h> 46 #include <sys/systm.h> 47 #include <sys/fcntl.h> 48 #include <sys/kernel.h> 49 #include <sys/lock.h> 50 #include <sys/malloc.h> 51 #include <sys/mount.h> 52 #include <sys/namei.h> 53 #include <sys/proc.h> 54 #include <sys/vnode.h> 55 #include <sys/jail.h> 56 57 #include <fs/nullfs/null.h> 58 59 static MALLOC_DEFINE(M_NULLFSMNT, "nullfs_mount", "NULLFS mount structure"); 60 61 static vfs_fhtovp_t nullfs_fhtovp; 62 static vfs_mount_t nullfs_mount; 63 static vfs_quotactl_t nullfs_quotactl; 64 static vfs_root_t nullfs_root; 65 static vfs_sync_t nullfs_sync; 66 static vfs_statfs_t nullfs_statfs; 67 static vfs_unmount_t nullfs_unmount; 68 static vfs_vget_t nullfs_vget; 69 static vfs_extattrctl_t nullfs_extattrctl; 70 71 /* 72 * Mount null layer 73 */ 74 static int 75 nullfs_mount(struct mount *mp) 76 { 77 struct vnode *lowerrootvp; 78 struct vnode *nullm_rootvp; 79 struct null_mount *xmp; 80 struct null_node *nn; 81 struct nameidata nd, *ndp; 82 char *target; 83 int error, len; 84 bool isvnunlocked; 85 86 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp); 87 88 if (mp->mnt_flag & MNT_ROOTFS) 89 return (EOPNOTSUPP); 90 91 /* 92 * Update is a no-op 93 */ 94 if (mp->mnt_flag & MNT_UPDATE) { 95 /* 96 * Only support update mounts for NFS export. 97 */ 98 if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0)) 99 return (0); 100 else 101 return (EOPNOTSUPP); 102 } 103 104 /* 105 * Get argument 106 */ 107 error = vfs_getopt(mp->mnt_optnew, "from", (void **)&target, &len); 108 if (error != 0) 109 error = vfs_getopt(mp->mnt_optnew, "target", (void **)&target, &len); 110 if (error || target[len - 1] != '\0') 111 return (EINVAL); 112 113 /* 114 * Unlock lower node to avoid possible deadlock. 115 */ 116 if (mp->mnt_vnodecovered->v_op == &null_vnodeops && 117 VOP_ISLOCKED(mp->mnt_vnodecovered) == LK_EXCLUSIVE) { 118 VOP_UNLOCK(mp->mnt_vnodecovered); 119 isvnunlocked = true; 120 } else { 121 isvnunlocked = false; 122 } 123 124 /* 125 * Find lower node 126 */ 127 ndp = &nd; 128 NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF, UIO_SYSSPACE, target); 129 error = namei(ndp); 130 131 /* 132 * Re-lock vnode. 133 * XXXKIB This is deadlock-prone as well. 134 */ 135 if (isvnunlocked) 136 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY); 137 138 if (error) 139 return (error); 140 NDFREE(ndp, NDF_ONLY_PNBUF); 141 142 /* 143 * Sanity check on lower vnode 144 */ 145 lowerrootvp = ndp->ni_vp; 146 147 /* 148 * Check multi null mount to avoid `lock against myself' panic. 149 */ 150 if (mp->mnt_vnodecovered->v_op == &null_vnodeops) { 151 nn = VTONULL(mp->mnt_vnodecovered); 152 if (nn == NULL || lowerrootvp == nn->null_lowervp) { 153 NULLFSDEBUG("nullfs_mount: multi null mount?\n"); 154 vput(lowerrootvp); 155 return (EDEADLK); 156 } 157 } 158 159 xmp = (struct null_mount *) malloc(sizeof(struct null_mount), 160 M_NULLFSMNT, M_WAITOK | M_ZERO); 161 162 /* 163 * Save pointer to underlying FS and the reference to the 164 * lower root vnode. 165 */ 166 xmp->nullm_vfs = vfs_register_upper_from_vp(lowerrootvp, mp, 167 &xmp->upper_node); 168 if (xmp->nullm_vfs == NULL) { 169 vput(lowerrootvp); 170 free(xmp, M_NULLFSMNT); 171 return (ENOENT); 172 } 173 vref(lowerrootvp); 174 xmp->nullm_lowerrootvp = lowerrootvp; 175 mp->mnt_data = xmp; 176 177 /* 178 * Make sure the node alias worked. 179 */ 180 error = null_nodeget(mp, lowerrootvp, &nullm_rootvp); 181 if (error != 0) { 182 vfs_unregister_upper(xmp->nullm_vfs, &xmp->upper_node); 183 vrele(lowerrootvp); 184 free(xmp, M_NULLFSMNT); 185 return (error); 186 } 187 188 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) { 189 MNT_ILOCK(mp); 190 mp->mnt_flag |= MNT_LOCAL; 191 MNT_IUNLOCK(mp); 192 } 193 194 xmp->nullm_flags |= NULLM_CACHE; 195 if (vfs_getopt(mp->mnt_optnew, "nocache", NULL, NULL) == 0 || 196 (xmp->nullm_vfs->mnt_kern_flag & MNTK_NULL_NOCACHE) != 0) 197 xmp->nullm_flags &= ~NULLM_CACHE; 198 199 if ((xmp->nullm_flags & NULLM_CACHE) != 0) { 200 vfs_register_for_notification(xmp->nullm_vfs, mp, 201 &xmp->notify_node); 202 } 203 204 MNT_ILOCK(mp); 205 if ((xmp->nullm_flags & NULLM_CACHE) != 0) { 206 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & 207 (MNTK_SHARED_WRITES | MNTK_LOOKUP_SHARED | 208 MNTK_EXTENDED_SHARED); 209 } 210 mp->mnt_kern_flag |= MNTK_LOOKUP_EXCL_DOTDOT | MNTK_NOMSYNC; 211 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & 212 (MNTK_USES_BCACHE | MNTK_NO_IOPF | MNTK_UNMAPPED_BUFS); 213 MNT_IUNLOCK(mp); 214 vfs_getnewfsid(mp); 215 vfs_mountedfrom(mp, target); 216 vput(nullm_rootvp); 217 218 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 219 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 220 return (0); 221 } 222 223 /* 224 * Free reference to null layer 225 */ 226 static int 227 nullfs_unmount(mp, mntflags) 228 struct mount *mp; 229 int mntflags; 230 { 231 struct null_mount *mntdata; 232 int error, flags; 233 234 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 235 236 if (mntflags & MNT_FORCE) 237 flags = FORCECLOSE; 238 else 239 flags = 0; 240 241 for (;;) { 242 /* There is 1 extra root vnode reference (nullm_rootvp). */ 243 error = vflush(mp, 0, flags, curthread); 244 if (error) 245 return (error); 246 MNT_ILOCK(mp); 247 if (mp->mnt_nvnodelistsize == 0) { 248 MNT_IUNLOCK(mp); 249 break; 250 } 251 MNT_IUNLOCK(mp); 252 if ((mntflags & MNT_FORCE) == 0) 253 return (EBUSY); 254 } 255 256 /* 257 * Finally, throw away the null_mount structure 258 */ 259 mntdata = mp->mnt_data; 260 if ((mntdata->nullm_flags & NULLM_CACHE) != 0) { 261 vfs_unregister_for_notification(mntdata->nullm_vfs, 262 &mntdata->notify_node); 263 } 264 vfs_unregister_upper(mntdata->nullm_vfs, &mntdata->upper_node); 265 vrele(mntdata->nullm_lowerrootvp); 266 mp->mnt_data = NULL; 267 free(mntdata, M_NULLFSMNT); 268 return (0); 269 } 270 271 static int 272 nullfs_root(mp, flags, vpp) 273 struct mount *mp; 274 int flags; 275 struct vnode **vpp; 276 { 277 struct vnode *vp; 278 struct null_mount *mntdata; 279 int error; 280 281 mntdata = MOUNTTONULLMOUNT(mp); 282 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p)\n", mp, 283 mntdata->nullm_lowerrootvp); 284 285 error = vget(mntdata->nullm_lowerrootvp, flags); 286 if (error == 0) { 287 error = null_nodeget(mp, mntdata->nullm_lowerrootvp, &vp); 288 if (error == 0) { 289 *vpp = vp; 290 } 291 } 292 return (error); 293 } 294 295 static int 296 nullfs_quotactl(mp, cmd, uid, arg, mp_busy) 297 struct mount *mp; 298 int cmd; 299 uid_t uid; 300 void *arg; 301 bool *mp_busy; 302 { 303 struct mount *lowermp; 304 struct null_mount *mntdata; 305 int error; 306 bool unbusy; 307 308 mntdata = MOUNTTONULLMOUNT(mp); 309 lowermp = atomic_load_ptr(&mntdata->nullm_vfs); 310 KASSERT(*mp_busy == true, ("upper mount not busy")); 311 /* 312 * See comment in sys_quotactl() for an explanation of why the 313 * lower mount needs to be busied by the caller of VFS_QUOTACTL() 314 * but may be unbusied by the implementation. We must unbusy 315 * the upper mount for the same reason; otherwise a namei lookup 316 * issued by the VFS_QUOTACTL() implementation could traverse the 317 * upper mount and deadlock. 318 */ 319 vfs_unbusy(mp); 320 *mp_busy = false; 321 unbusy = true; 322 error = vfs_busy(lowermp, 0); 323 if (error == 0) 324 error = VFS_QUOTACTL(lowermp, cmd, uid, arg, &unbusy); 325 if (unbusy) 326 vfs_unbusy(lowermp); 327 328 return (error); 329 } 330 331 static int 332 nullfs_statfs(mp, sbp) 333 struct mount *mp; 334 struct statfs *sbp; 335 { 336 int error; 337 struct statfs *mstat; 338 339 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 340 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 341 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 342 343 mstat = malloc(sizeof(struct statfs), M_STATFS, M_WAITOK | M_ZERO); 344 345 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, mstat); 346 if (error) { 347 free(mstat, M_STATFS); 348 return (error); 349 } 350 351 /* now copy across the "interesting" information and fake the rest */ 352 sbp->f_type = mstat->f_type; 353 sbp->f_flags = (sbp->f_flags & (MNT_RDONLY | MNT_NOEXEC | MNT_NOSUID | 354 MNT_UNION | MNT_NOSYMFOLLOW | MNT_AUTOMOUNTED)) | 355 (mstat->f_flags & ~(MNT_ROOTFS | MNT_AUTOMOUNTED)); 356 sbp->f_bsize = mstat->f_bsize; 357 sbp->f_iosize = mstat->f_iosize; 358 sbp->f_blocks = mstat->f_blocks; 359 sbp->f_bfree = mstat->f_bfree; 360 sbp->f_bavail = mstat->f_bavail; 361 sbp->f_files = mstat->f_files; 362 sbp->f_ffree = mstat->f_ffree; 363 364 free(mstat, M_STATFS); 365 return (0); 366 } 367 368 static int 369 nullfs_sync(mp, waitfor) 370 struct mount *mp; 371 int waitfor; 372 { 373 /* 374 * XXX - Assumes no data cached at null layer. 375 */ 376 return (0); 377 } 378 379 static int 380 nullfs_vget(mp, ino, flags, vpp) 381 struct mount *mp; 382 ino_t ino; 383 int flags; 384 struct vnode **vpp; 385 { 386 int error; 387 388 KASSERT((flags & LK_TYPE_MASK) != 0, 389 ("nullfs_vget: no lock requested")); 390 391 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp); 392 if (error != 0) 393 return (error); 394 return (null_nodeget(mp, *vpp, vpp)); 395 } 396 397 static int 398 nullfs_fhtovp(mp, fidp, flags, vpp) 399 struct mount *mp; 400 struct fid *fidp; 401 int flags; 402 struct vnode **vpp; 403 { 404 int error; 405 406 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, flags, 407 vpp); 408 if (error != 0) 409 return (error); 410 return (null_nodeget(mp, *vpp, vpp)); 411 } 412 413 static int 414 nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname) 415 struct mount *mp; 416 int cmd; 417 struct vnode *filename_vp; 418 int namespace; 419 const char *attrname; 420 { 421 422 return (VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, 423 filename_vp, namespace, attrname)); 424 } 425 426 static void 427 nullfs_reclaim_lowervp(struct mount *mp, struct vnode *lowervp) 428 { 429 struct vnode *vp; 430 431 vp = null_hashget(mp, lowervp); 432 if (vp == NULL) 433 return; 434 VTONULL(vp)->null_flags |= NULLV_NOUNLOCK; 435 vgone(vp); 436 vput(vp); 437 } 438 439 static void 440 nullfs_unlink_lowervp(struct mount *mp, struct vnode *lowervp) 441 { 442 struct vnode *vp; 443 struct null_node *xp; 444 445 vp = null_hashget(mp, lowervp); 446 if (vp == NULL) 447 return; 448 xp = VTONULL(vp); 449 xp->null_flags |= NULLV_DROP | NULLV_NOUNLOCK; 450 vhold(vp); 451 vunref(vp); 452 453 if (vp->v_usecount == 0) { 454 /* 455 * If vunref() dropped the last use reference on the 456 * nullfs vnode, it must be reclaimed, and its lock 457 * was split from the lower vnode lock. Need to do 458 * extra unlock before allowing the final vdrop() to 459 * free the vnode. 460 */ 461 KASSERT(VN_IS_DOOMED(vp), 462 ("not reclaimed nullfs vnode %p", vp)); 463 VOP_UNLOCK(vp); 464 } else { 465 /* 466 * Otherwise, the nullfs vnode still shares the lock 467 * with the lower vnode, and must not be unlocked. 468 * Also clear the NULLV_NOUNLOCK, the flag is not 469 * relevant for future reclamations. 470 */ 471 ASSERT_VOP_ELOCKED(vp, "unlink_lowervp"); 472 KASSERT(!VN_IS_DOOMED(vp), 473 ("reclaimed nullfs vnode %p", vp)); 474 xp->null_flags &= ~NULLV_NOUNLOCK; 475 } 476 vdrop(vp); 477 } 478 479 static struct vfsops null_vfsops = { 480 .vfs_extattrctl = nullfs_extattrctl, 481 .vfs_fhtovp = nullfs_fhtovp, 482 .vfs_init = nullfs_init, 483 .vfs_mount = nullfs_mount, 484 .vfs_quotactl = nullfs_quotactl, 485 .vfs_root = nullfs_root, 486 .vfs_statfs = nullfs_statfs, 487 .vfs_sync = nullfs_sync, 488 .vfs_uninit = nullfs_uninit, 489 .vfs_unmount = nullfs_unmount, 490 .vfs_vget = nullfs_vget, 491 .vfs_reclaim_lowervp = nullfs_reclaim_lowervp, 492 .vfs_unlink_lowervp = nullfs_unlink_lowervp, 493 }; 494 495 VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK | VFCF_JAIL); 496