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, 0); 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, 0); 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; 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; 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 /* There is 1 extra root vnode reference (nullm_rootvp). */ 248 error = vflush(mp, 1, flags, curthread); 249 if (error) 250 return (error); 251 252 /* 253 * Finally, throw away the null_mount structure 254 */ 255 mntdata = mp->mnt_data; 256 ump = mntdata->nullm_vfs; 257 if ((mntdata->nullm_flags & NULLM_CACHE) != 0) { 258 MNT_ILOCK(ump); 259 while ((ump->mnt_kern_flag & MNTK_VGONE_UPPER) != 0) { 260 ump->mnt_kern_flag |= MNTK_VGONE_WAITER; 261 msleep(&ump->mnt_uppers, &ump->mnt_mtx, 0, "vgnupw", 0); 262 } 263 TAILQ_REMOVE(&ump->mnt_uppers, mp, mnt_upper_link); 264 MNT_IUNLOCK(ump); 265 } 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; 278 279 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp, 280 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 281 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 282 283 /* 284 * Return locked reference to root. 285 */ 286 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 287 VREF(vp); 288 289 ASSERT_VOP_UNLOCKED(vp, "root vnode is locked"); 290 vn_lock(vp, flags | LK_RETRY); 291 *vpp = vp; 292 return 0; 293 } 294 295 static int 296 nullfs_quotactl(mp, cmd, uid, arg) 297 struct mount *mp; 298 int cmd; 299 uid_t uid; 300 void *arg; 301 { 302 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg); 303 } 304 305 static int 306 nullfs_statfs(mp, sbp) 307 struct mount *mp; 308 struct statfs *sbp; 309 { 310 int error; 311 struct statfs *mstat; 312 313 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 314 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 315 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 316 317 mstat = malloc(sizeof(struct statfs), M_STATFS, M_WAITOK | M_ZERO); 318 319 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, mstat); 320 if (error) { 321 free(mstat, M_STATFS); 322 return (error); 323 } 324 325 /* now copy across the "interesting" information and fake the rest */ 326 sbp->f_type = mstat->f_type; 327 sbp->f_flags = (sbp->f_flags & (MNT_RDONLY | MNT_NOEXEC | MNT_NOSUID | 328 MNT_UNION | MNT_NOSYMFOLLOW | MNT_AUTOMOUNTED)) | 329 (mstat->f_flags & ~(MNT_ROOTFS | MNT_AUTOMOUNTED)); 330 sbp->f_bsize = mstat->f_bsize; 331 sbp->f_iosize = mstat->f_iosize; 332 sbp->f_blocks = mstat->f_blocks; 333 sbp->f_bfree = mstat->f_bfree; 334 sbp->f_bavail = mstat->f_bavail; 335 sbp->f_files = mstat->f_files; 336 sbp->f_ffree = mstat->f_ffree; 337 338 free(mstat, M_STATFS); 339 return (0); 340 } 341 342 static int 343 nullfs_sync(mp, waitfor) 344 struct mount *mp; 345 int waitfor; 346 { 347 /* 348 * XXX - Assumes no data cached at null layer. 349 */ 350 return (0); 351 } 352 353 static int 354 nullfs_vget(mp, ino, flags, vpp) 355 struct mount *mp; 356 ino_t ino; 357 int flags; 358 struct vnode **vpp; 359 { 360 int error; 361 362 KASSERT((flags & LK_TYPE_MASK) != 0, 363 ("nullfs_vget: no lock requested")); 364 365 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp); 366 if (error != 0) 367 return (error); 368 return (null_nodeget(mp, *vpp, vpp)); 369 } 370 371 static int 372 nullfs_fhtovp(mp, fidp, flags, vpp) 373 struct mount *mp; 374 struct fid *fidp; 375 int flags; 376 struct vnode **vpp; 377 { 378 int error; 379 380 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, flags, 381 vpp); 382 if (error != 0) 383 return (error); 384 return (null_nodeget(mp, *vpp, vpp)); 385 } 386 387 static int 388 nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname) 389 struct mount *mp; 390 int cmd; 391 struct vnode *filename_vp; 392 int namespace; 393 const char *attrname; 394 { 395 396 return (VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, 397 filename_vp, namespace, attrname)); 398 } 399 400 static void 401 nullfs_reclaim_lowervp(struct mount *mp, struct vnode *lowervp) 402 { 403 struct vnode *vp; 404 405 vp = null_hashget(mp, lowervp); 406 if (vp == NULL) 407 return; 408 VTONULL(vp)->null_flags |= NULLV_NOUNLOCK; 409 vgone(vp); 410 vput(vp); 411 } 412 413 static void 414 nullfs_unlink_lowervp(struct mount *mp, struct vnode *lowervp) 415 { 416 struct vnode *vp; 417 struct null_node *xp; 418 419 vp = null_hashget(mp, lowervp); 420 if (vp == NULL) 421 return; 422 xp = VTONULL(vp); 423 xp->null_flags |= NULLV_DROP | NULLV_NOUNLOCK; 424 vhold(vp); 425 vunref(vp); 426 427 if (vp->v_usecount == 0) { 428 /* 429 * If vunref() dropped the last use reference on the 430 * nullfs vnode, it must be reclaimed, and its lock 431 * was split from the lower vnode lock. Need to do 432 * extra unlock before allowing the final vdrop() to 433 * free the vnode. 434 */ 435 KASSERT((vp->v_iflag & VI_DOOMED) != 0, 436 ("not reclaimed nullfs vnode %p", vp)); 437 VOP_UNLOCK(vp, 0); 438 } else { 439 /* 440 * Otherwise, the nullfs vnode still shares the lock 441 * with the lower vnode, and must not be unlocked. 442 * Also clear the NULLV_NOUNLOCK, the flag is not 443 * relevant for future reclamations. 444 */ 445 ASSERT_VOP_ELOCKED(vp, "unlink_lowervp"); 446 KASSERT((vp->v_iflag & VI_DOOMED) == 0, 447 ("reclaimed nullfs vnode %p", vp)); 448 xp->null_flags &= ~NULLV_NOUNLOCK; 449 } 450 vdrop(vp); 451 } 452 453 static struct vfsops null_vfsops = { 454 .vfs_extattrctl = nullfs_extattrctl, 455 .vfs_fhtovp = nullfs_fhtovp, 456 .vfs_init = nullfs_init, 457 .vfs_mount = nullfs_mount, 458 .vfs_quotactl = nullfs_quotactl, 459 .vfs_root = nullfs_root, 460 .vfs_statfs = nullfs_statfs, 461 .vfs_sync = nullfs_sync, 462 .vfs_uninit = nullfs_uninit, 463 .vfs_unmount = nullfs_unmount, 464 .vfs_vget = nullfs_vget, 465 .vfs_reclaim_lowervp = nullfs_reclaim_lowervp, 466 .vfs_unlink_lowervp = nullfs_unlink_lowervp, 467 }; 468 469 VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK | VFCF_JAIL); 470