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, curthread); 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_pin_from_vp(lowerrootvp); 167 if (xmp->nullm_vfs == NULL) { 168 vput(lowerrootvp); 169 free(xmp, M_NULLFSMNT); 170 return (ENOENT); 171 } 172 vref(lowerrootvp); 173 xmp->nullm_lowerrootvp = lowerrootvp; 174 mp->mnt_data = xmp; 175 176 /* 177 * Make sure the node alias worked. 178 */ 179 error = null_nodeget(mp, lowerrootvp, &nullm_rootvp); 180 if (error != 0) { 181 vfs_unpin(xmp->nullm_vfs); 182 vrele(lowerrootvp); 183 free(xmp, M_NULLFSMNT); 184 return (error); 185 } 186 187 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) { 188 MNT_ILOCK(mp); 189 mp->mnt_flag |= MNT_LOCAL; 190 MNT_IUNLOCK(mp); 191 } 192 193 xmp->nullm_flags |= NULLM_CACHE; 194 if (vfs_getopt(mp->mnt_optnew, "nocache", NULL, NULL) == 0 || 195 (xmp->nullm_vfs->mnt_kern_flag & MNTK_NULL_NOCACHE) != 0) 196 xmp->nullm_flags &= ~NULLM_CACHE; 197 198 MNT_ILOCK(mp); 199 if ((xmp->nullm_flags & NULLM_CACHE) != 0) { 200 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & 201 (MNTK_SHARED_WRITES | MNTK_LOOKUP_SHARED | 202 MNTK_EXTENDED_SHARED); 203 } 204 mp->mnt_kern_flag |= MNTK_LOOKUP_EXCL_DOTDOT | MNTK_NOMSYNC; 205 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & 206 (MNTK_USES_BCACHE | MNTK_NO_IOPF | MNTK_UNMAPPED_BUFS); 207 MNT_IUNLOCK(mp); 208 vfs_getnewfsid(mp); 209 if ((xmp->nullm_flags & NULLM_CACHE) != 0) { 210 MNT_ILOCK(xmp->nullm_vfs); 211 TAILQ_INSERT_TAIL(&xmp->nullm_vfs->mnt_uppers, mp, 212 mnt_upper_link); 213 MNT_IUNLOCK(xmp->nullm_vfs); 214 } 215 216 vfs_mountedfrom(mp, target); 217 vput(nullm_rootvp); 218 219 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 220 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 221 return (0); 222 } 223 224 /* 225 * Free reference to null layer 226 */ 227 static int 228 nullfs_unmount(mp, mntflags) 229 struct mount *mp; 230 int mntflags; 231 { 232 struct null_mount *mntdata; 233 struct mount *ump; 234 int error, flags; 235 236 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 237 238 if (mntflags & MNT_FORCE) 239 flags = FORCECLOSE; 240 else 241 flags = 0; 242 243 for (;;) { 244 /* There is 1 extra root vnode reference (nullm_rootvp). */ 245 error = vflush(mp, 0, flags, curthread); 246 if (error) 247 return (error); 248 MNT_ILOCK(mp); 249 if (mp->mnt_nvnodelistsize == 0) { 250 MNT_IUNLOCK(mp); 251 break; 252 } 253 MNT_IUNLOCK(mp); 254 if ((mntflags & MNT_FORCE) == 0) 255 return (EBUSY); 256 } 257 258 /* 259 * Finally, throw away the null_mount structure 260 */ 261 mntdata = mp->mnt_data; 262 ump = mntdata->nullm_vfs; 263 if ((mntdata->nullm_flags & NULLM_CACHE) != 0) { 264 MNT_ILOCK(ump); 265 while ((ump->mnt_kern_flag & MNTK_VGONE_UPPER) != 0) { 266 ump->mnt_kern_flag |= MNTK_VGONE_WAITER; 267 msleep(&ump->mnt_uppers, &ump->mnt_mtx, 0, "vgnupw", 0); 268 } 269 TAILQ_REMOVE(&ump->mnt_uppers, mp, mnt_upper_link); 270 MNT_IUNLOCK(ump); 271 } 272 vfs_unpin(ump); 273 vrele(mntdata->nullm_lowerrootvp); 274 mp->mnt_data = NULL; 275 free(mntdata, M_NULLFSMNT); 276 return (0); 277 } 278 279 static int 280 nullfs_root(mp, flags, vpp) 281 struct mount *mp; 282 int flags; 283 struct vnode **vpp; 284 { 285 struct vnode *vp; 286 struct null_mount *mntdata; 287 int error; 288 289 mntdata = MOUNTTONULLMOUNT(mp); 290 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p)\n", mp, 291 mntdata->nullm_lowerrootvp); 292 293 error = vget(mntdata->nullm_lowerrootvp, flags); 294 if (error == 0) { 295 error = null_nodeget(mp, mntdata->nullm_lowerrootvp, &vp); 296 if (error == 0) { 297 *vpp = vp; 298 } 299 } 300 return (error); 301 } 302 303 static int 304 nullfs_quotactl(mp, cmd, uid, arg, mp_busy) 305 struct mount *mp; 306 int cmd; 307 uid_t uid; 308 void *arg; 309 bool *mp_busy; 310 { 311 struct mount *lowermp; 312 struct null_mount *mntdata; 313 int error; 314 bool unbusy; 315 316 mntdata = MOUNTTONULLMOUNT(mp); 317 lowermp = atomic_load_ptr(&mntdata->nullm_vfs); 318 KASSERT(*mp_busy == true, ("upper mount not busy")); 319 /* 320 * See comment in sys_quotactl() for an explanation of why the 321 * lower mount needs to be busied by the caller of VFS_QUOTACTL() 322 * but may be unbusied by the implementation. We must unbusy 323 * the upper mount for the same reason; otherwise a namei lookup 324 * issued by the VFS_QUOTACTL() implementation could traverse the 325 * upper mount and deadlock. 326 */ 327 vfs_unbusy(mp); 328 *mp_busy = false; 329 unbusy = true; 330 error = vfs_busy(lowermp, 0); 331 if (error == 0) 332 error = VFS_QUOTACTL(lowermp, cmd, uid, arg, &unbusy); 333 if (unbusy) 334 vfs_unbusy(lowermp); 335 336 return (error); 337 } 338 339 static int 340 nullfs_statfs(mp, sbp) 341 struct mount *mp; 342 struct statfs *sbp; 343 { 344 int error; 345 struct statfs *mstat; 346 347 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 348 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 349 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 350 351 mstat = malloc(sizeof(struct statfs), M_STATFS, M_WAITOK | M_ZERO); 352 353 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, mstat); 354 if (error) { 355 free(mstat, M_STATFS); 356 return (error); 357 } 358 359 /* now copy across the "interesting" information and fake the rest */ 360 sbp->f_type = mstat->f_type; 361 sbp->f_flags = (sbp->f_flags & (MNT_RDONLY | MNT_NOEXEC | MNT_NOSUID | 362 MNT_UNION | MNT_NOSYMFOLLOW | MNT_AUTOMOUNTED)) | 363 (mstat->f_flags & ~(MNT_ROOTFS | MNT_AUTOMOUNTED)); 364 sbp->f_bsize = mstat->f_bsize; 365 sbp->f_iosize = mstat->f_iosize; 366 sbp->f_blocks = mstat->f_blocks; 367 sbp->f_bfree = mstat->f_bfree; 368 sbp->f_bavail = mstat->f_bavail; 369 sbp->f_files = mstat->f_files; 370 sbp->f_ffree = mstat->f_ffree; 371 372 free(mstat, M_STATFS); 373 return (0); 374 } 375 376 static int 377 nullfs_sync(mp, waitfor) 378 struct mount *mp; 379 int waitfor; 380 { 381 /* 382 * XXX - Assumes no data cached at null layer. 383 */ 384 return (0); 385 } 386 387 static int 388 nullfs_vget(mp, ino, flags, vpp) 389 struct mount *mp; 390 ino_t ino; 391 int flags; 392 struct vnode **vpp; 393 { 394 int error; 395 396 KASSERT((flags & LK_TYPE_MASK) != 0, 397 ("nullfs_vget: no lock requested")); 398 399 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp); 400 if (error != 0) 401 return (error); 402 return (null_nodeget(mp, *vpp, vpp)); 403 } 404 405 static int 406 nullfs_fhtovp(mp, fidp, flags, vpp) 407 struct mount *mp; 408 struct fid *fidp; 409 int flags; 410 struct vnode **vpp; 411 { 412 int error; 413 414 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, flags, 415 vpp); 416 if (error != 0) 417 return (error); 418 return (null_nodeget(mp, *vpp, vpp)); 419 } 420 421 static int 422 nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname) 423 struct mount *mp; 424 int cmd; 425 struct vnode *filename_vp; 426 int namespace; 427 const char *attrname; 428 { 429 430 return (VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, 431 filename_vp, namespace, attrname)); 432 } 433 434 static void 435 nullfs_reclaim_lowervp(struct mount *mp, struct vnode *lowervp) 436 { 437 struct vnode *vp; 438 439 vp = null_hashget(mp, lowervp); 440 if (vp == NULL) 441 return; 442 VTONULL(vp)->null_flags |= NULLV_NOUNLOCK; 443 vgone(vp); 444 vput(vp); 445 } 446 447 static void 448 nullfs_unlink_lowervp(struct mount *mp, struct vnode *lowervp) 449 { 450 struct vnode *vp; 451 struct null_node *xp; 452 453 vp = null_hashget(mp, lowervp); 454 if (vp == NULL) 455 return; 456 xp = VTONULL(vp); 457 xp->null_flags |= NULLV_DROP | NULLV_NOUNLOCK; 458 vhold(vp); 459 vunref(vp); 460 461 if (vp->v_usecount == 0) { 462 /* 463 * If vunref() dropped the last use reference on the 464 * nullfs vnode, it must be reclaimed, and its lock 465 * was split from the lower vnode lock. Need to do 466 * extra unlock before allowing the final vdrop() to 467 * free the vnode. 468 */ 469 KASSERT(VN_IS_DOOMED(vp), 470 ("not reclaimed nullfs vnode %p", vp)); 471 VOP_UNLOCK(vp); 472 } else { 473 /* 474 * Otherwise, the nullfs vnode still shares the lock 475 * with the lower vnode, and must not be unlocked. 476 * Also clear the NULLV_NOUNLOCK, the flag is not 477 * relevant for future reclamations. 478 */ 479 ASSERT_VOP_ELOCKED(vp, "unlink_lowervp"); 480 KASSERT(!VN_IS_DOOMED(vp), 481 ("reclaimed nullfs vnode %p", vp)); 482 xp->null_flags &= ~NULLV_NOUNLOCK; 483 } 484 vdrop(vp); 485 } 486 487 static struct vfsops null_vfsops = { 488 .vfs_extattrctl = nullfs_extattrctl, 489 .vfs_fhtovp = nullfs_fhtovp, 490 .vfs_init = nullfs_init, 491 .vfs_mount = nullfs_mount, 492 .vfs_quotactl = nullfs_quotactl, 493 .vfs_root = nullfs_root, 494 .vfs_statfs = nullfs_statfs, 495 .vfs_sync = nullfs_sync, 496 .vfs_uninit = nullfs_uninit, 497 .vfs_unmount = nullfs_unmount, 498 .vfs_vget = nullfs_vget, 499 .vfs_reclaim_lowervp = nullfs_reclaim_lowervp, 500 .vfs_unlink_lowervp = nullfs_unlink_lowervp, 501 }; 502 503 VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK | VFCF_JAIL); 504