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, *vp; 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, "target", (void **)&target, &len); 108 if (error || target[len - 1] != '\0') 109 return (EINVAL); 110 111 /* 112 * Unlock lower node to avoid possible deadlock. 113 */ 114 if (mp->mnt_vnodecovered->v_op == &null_vnodeops && 115 VOP_ISLOCKED(mp->mnt_vnodecovered) == LK_EXCLUSIVE) { 116 VOP_UNLOCK(mp->mnt_vnodecovered); 117 isvnunlocked = true; 118 } else { 119 isvnunlocked = false; 120 } 121 122 /* 123 * Find lower node 124 */ 125 ndp = &nd; 126 NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF, UIO_SYSSPACE, target, curthread); 127 error = namei(ndp); 128 129 /* 130 * Re-lock vnode. 131 * XXXKIB This is deadlock-prone as well. 132 */ 133 if (isvnunlocked) 134 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY); 135 136 if (error) 137 return (error); 138 NDFREE(ndp, NDF_ONLY_PNBUF); 139 140 /* 141 * Sanity check on lower vnode 142 */ 143 lowerrootvp = ndp->ni_vp; 144 145 /* 146 * Check multi null mount to avoid `lock against myself' panic. 147 */ 148 if (mp->mnt_vnodecovered->v_op == &null_vnodeops) { 149 nn = VTONULL(mp->mnt_vnodecovered); 150 if (nn == NULL || lowerrootvp == nn->null_lowervp) { 151 NULLFSDEBUG("nullfs_mount: multi null mount?\n"); 152 vput(lowerrootvp); 153 return (EDEADLK); 154 } 155 } 156 157 xmp = (struct null_mount *) malloc(sizeof(struct null_mount), 158 M_NULLFSMNT, M_WAITOK | M_ZERO); 159 160 /* 161 * Save reference to underlying FS 162 */ 163 xmp->nullm_vfs = lowerrootvp->v_mount; 164 165 /* 166 * Save reference. Each mount also holds 167 * a reference on the root vnode. 168 */ 169 error = null_nodeget(mp, lowerrootvp, &vp); 170 /* 171 * Make sure the node alias worked 172 */ 173 if (error) { 174 free(xmp, M_NULLFSMNT); 175 return (error); 176 } 177 178 /* 179 * Keep a held reference to the root vnode. 180 * It is vrele'd in nullfs_unmount. 181 */ 182 nullm_rootvp = vp; 183 nullm_rootvp->v_vflag |= VV_ROOT; 184 xmp->nullm_rootvp = nullm_rootvp; 185 186 /* 187 * Unlock the node (either the lower or the alias) 188 */ 189 VOP_UNLOCK(vp); 190 191 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) { 192 MNT_ILOCK(mp); 193 mp->mnt_flag |= MNT_LOCAL; 194 MNT_IUNLOCK(mp); 195 } 196 197 xmp->nullm_flags |= NULLM_CACHE; 198 if (vfs_getopt(mp->mnt_optnew, "nocache", NULL, NULL) == 0 || 199 (xmp->nullm_vfs->mnt_kern_flag & MNTK_NULL_NOCACHE) != 0) 200 xmp->nullm_flags &= ~NULLM_CACHE; 201 202 MNT_ILOCK(mp); 203 if ((xmp->nullm_flags & NULLM_CACHE) != 0) { 204 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & 205 (MNTK_SHARED_WRITES | MNTK_LOOKUP_SHARED | 206 MNTK_EXTENDED_SHARED); 207 } 208 mp->mnt_kern_flag |= MNTK_LOOKUP_EXCL_DOTDOT | MNTK_NOMSYNC; 209 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & 210 (MNTK_USES_BCACHE | MNTK_NO_IOPF | MNTK_UNMAPPED_BUFS); 211 MNT_IUNLOCK(mp); 212 mp->mnt_data = xmp; 213 vfs_getnewfsid(mp); 214 if ((xmp->nullm_flags & NULLM_CACHE) != 0) { 215 MNT_ILOCK(xmp->nullm_vfs); 216 TAILQ_INSERT_TAIL(&xmp->nullm_vfs->mnt_uppers, mp, 217 mnt_upper_link); 218 MNT_IUNLOCK(xmp->nullm_vfs); 219 } 220 221 vfs_mountedfrom(mp, target); 222 223 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 224 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 225 return (0); 226 } 227 228 /* 229 * Free reference to null layer 230 */ 231 static int 232 nullfs_unmount(mp, mntflags) 233 struct mount *mp; 234 int mntflags; 235 { 236 struct null_mount *mntdata; 237 struct mount *ump; 238 int error, flags, rootrefs; 239 240 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 241 242 if (mntflags & MNT_FORCE) 243 flags = FORCECLOSE; 244 else 245 flags = 0; 246 247 for (rootrefs = 1;; rootrefs = 0) { 248 /* There is 1 extra root vnode reference (nullm_rootvp). */ 249 error = vflush(mp, rootrefs, flags, curthread); 250 if (error) 251 return (error); 252 MNT_ILOCK(mp); 253 if (mp->mnt_nvnodelistsize == 0) { 254 MNT_IUNLOCK(mp); 255 break; 256 } 257 MNT_IUNLOCK(mp); 258 if ((mntflags & MNT_FORCE) == 0) 259 return (EBUSY); 260 } 261 262 /* 263 * Finally, throw away the null_mount structure 264 */ 265 mntdata = mp->mnt_data; 266 ump = mntdata->nullm_vfs; 267 if ((mntdata->nullm_flags & NULLM_CACHE) != 0) { 268 MNT_ILOCK(ump); 269 while ((ump->mnt_kern_flag & MNTK_VGONE_UPPER) != 0) { 270 ump->mnt_kern_flag |= MNTK_VGONE_WAITER; 271 msleep(&ump->mnt_uppers, &ump->mnt_mtx, 0, "vgnupw", 0); 272 } 273 TAILQ_REMOVE(&ump->mnt_uppers, mp, mnt_upper_link); 274 MNT_IUNLOCK(ump); 275 } 276 mp->mnt_data = NULL; 277 free(mntdata, M_NULLFSMNT); 278 return (0); 279 } 280 281 static int 282 nullfs_root(mp, flags, vpp) 283 struct mount *mp; 284 int flags; 285 struct vnode **vpp; 286 { 287 struct vnode *vp; 288 289 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp, 290 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 291 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 292 293 /* 294 * Return locked reference to root. 295 */ 296 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 297 VREF(vp); 298 299 ASSERT_VOP_UNLOCKED(vp, "root vnode is locked"); 300 vn_lock(vp, flags | LK_RETRY); 301 *vpp = vp; 302 return 0; 303 } 304 305 static int 306 nullfs_quotactl(mp, cmd, uid, arg) 307 struct mount *mp; 308 int cmd; 309 uid_t uid; 310 void *arg; 311 { 312 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg); 313 } 314 315 static int 316 nullfs_statfs(mp, sbp) 317 struct mount *mp; 318 struct statfs *sbp; 319 { 320 int error; 321 struct statfs *mstat; 322 323 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 324 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 325 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 326 327 mstat = malloc(sizeof(struct statfs), M_STATFS, M_WAITOK | M_ZERO); 328 329 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, mstat); 330 if (error) { 331 free(mstat, M_STATFS); 332 return (error); 333 } 334 335 /* now copy across the "interesting" information and fake the rest */ 336 sbp->f_type = mstat->f_type; 337 sbp->f_flags = (sbp->f_flags & (MNT_RDONLY | MNT_NOEXEC | MNT_NOSUID | 338 MNT_UNION | MNT_NOSYMFOLLOW | MNT_AUTOMOUNTED)) | 339 (mstat->f_flags & ~(MNT_ROOTFS | MNT_AUTOMOUNTED)); 340 sbp->f_bsize = mstat->f_bsize; 341 sbp->f_iosize = mstat->f_iosize; 342 sbp->f_blocks = mstat->f_blocks; 343 sbp->f_bfree = mstat->f_bfree; 344 sbp->f_bavail = mstat->f_bavail; 345 sbp->f_files = mstat->f_files; 346 sbp->f_ffree = mstat->f_ffree; 347 348 free(mstat, M_STATFS); 349 return (0); 350 } 351 352 static int 353 nullfs_sync(mp, waitfor) 354 struct mount *mp; 355 int waitfor; 356 { 357 /* 358 * XXX - Assumes no data cached at null layer. 359 */ 360 return (0); 361 } 362 363 static int 364 nullfs_vget(mp, ino, flags, vpp) 365 struct mount *mp; 366 ino_t ino; 367 int flags; 368 struct vnode **vpp; 369 { 370 int error; 371 372 KASSERT((flags & LK_TYPE_MASK) != 0, 373 ("nullfs_vget: no lock requested")); 374 375 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp); 376 if (error != 0) 377 return (error); 378 return (null_nodeget(mp, *vpp, vpp)); 379 } 380 381 static int 382 nullfs_fhtovp(mp, fidp, flags, vpp) 383 struct mount *mp; 384 struct fid *fidp; 385 int flags; 386 struct vnode **vpp; 387 { 388 int error; 389 390 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, flags, 391 vpp); 392 if (error != 0) 393 return (error); 394 return (null_nodeget(mp, *vpp, vpp)); 395 } 396 397 static int 398 nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname) 399 struct mount *mp; 400 int cmd; 401 struct vnode *filename_vp; 402 int namespace; 403 const char *attrname; 404 { 405 406 return (VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, 407 filename_vp, namespace, attrname)); 408 } 409 410 static void 411 nullfs_reclaim_lowervp(struct mount *mp, struct vnode *lowervp) 412 { 413 struct vnode *vp; 414 415 vp = null_hashget(mp, lowervp); 416 if (vp == NULL) 417 return; 418 VTONULL(vp)->null_flags |= NULLV_NOUNLOCK; 419 vgone(vp); 420 vput(vp); 421 } 422 423 static void 424 nullfs_unlink_lowervp(struct mount *mp, struct vnode *lowervp) 425 { 426 struct vnode *vp; 427 struct null_node *xp; 428 429 vp = null_hashget(mp, lowervp); 430 if (vp == NULL) 431 return; 432 xp = VTONULL(vp); 433 xp->null_flags |= NULLV_DROP | NULLV_NOUNLOCK; 434 vhold(vp); 435 vunref(vp); 436 437 if (vp->v_usecount == 0) { 438 /* 439 * If vunref() dropped the last use reference on the 440 * nullfs vnode, it must be reclaimed, and its lock 441 * was split from the lower vnode lock. Need to do 442 * extra unlock before allowing the final vdrop() to 443 * free the vnode. 444 */ 445 KASSERT(VN_IS_DOOMED(vp), 446 ("not reclaimed nullfs vnode %p", vp)); 447 VOP_UNLOCK(vp); 448 } else { 449 /* 450 * Otherwise, the nullfs vnode still shares the lock 451 * with the lower vnode, and must not be unlocked. 452 * Also clear the NULLV_NOUNLOCK, the flag is not 453 * relevant for future reclamations. 454 */ 455 ASSERT_VOP_ELOCKED(vp, "unlink_lowervp"); 456 KASSERT(!VN_IS_DOOMED(vp), 457 ("reclaimed nullfs vnode %p", vp)); 458 xp->null_flags &= ~NULLV_NOUNLOCK; 459 } 460 vdrop(vp); 461 } 462 463 static struct vfsops null_vfsops = { 464 .vfs_extattrctl = nullfs_extattrctl, 465 .vfs_fhtovp = nullfs_fhtovp, 466 .vfs_init = nullfs_init, 467 .vfs_mount = nullfs_mount, 468 .vfs_quotactl = nullfs_quotactl, 469 .vfs_root = nullfs_root, 470 .vfs_statfs = nullfs_statfs, 471 .vfs_sync = nullfs_sync, 472 .vfs_uninit = nullfs_uninit, 473 .vfs_unmount = nullfs_unmount, 474 .vfs_vget = nullfs_vget, 475 .vfs_reclaim_lowervp = nullfs_reclaim_lowervp, 476 .vfs_unlink_lowervp = nullfs_unlink_lowervp, 477 }; 478 479 VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK | VFCF_JAIL); 480