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 int error = 0; 78 struct vnode *lowerrootvp, *vp; 79 struct vnode *nullm_rootvp; 80 struct null_mount *xmp; 81 struct thread *td = curthread; 82 char *target; 83 int isvnunlocked = 0, len; 84 struct nameidata nd, *ndp = &nd; 85 86 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp); 87 88 if (!prison_allow(td->td_ucred, PR_ALLOW_MOUNT_NULLFS)) 89 return (EPERM); 90 if (mp->mnt_flag & MNT_ROOTFS) 91 return (EOPNOTSUPP); 92 93 /* 94 * Update is a no-op 95 */ 96 if (mp->mnt_flag & MNT_UPDATE) { 97 /* 98 * Only support update mounts for NFS export. 99 */ 100 if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0)) 101 return (0); 102 else 103 return (EOPNOTSUPP); 104 } 105 106 /* 107 * Get argument 108 */ 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, 0); 119 isvnunlocked = 1; 120 } 121 /* 122 * Find lower node 123 */ 124 NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF, UIO_SYSSPACE, target, curthread); 125 error = namei(ndp); 126 127 /* 128 * Re-lock vnode. 129 * XXXKIB This is deadlock-prone as well. 130 */ 131 if (isvnunlocked) 132 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY); 133 134 if (error) 135 return (error); 136 NDFREE(ndp, NDF_ONLY_PNBUF); 137 138 /* 139 * Sanity check on lower vnode 140 */ 141 lowerrootvp = ndp->ni_vp; 142 143 /* 144 * Check multi null mount to avoid `lock against myself' panic. 145 */ 146 if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) { 147 NULLFSDEBUG("nullfs_mount: multi null mount?\n"); 148 vput(lowerrootvp); 149 return (EDEADLK); 150 } 151 152 xmp = (struct null_mount *) malloc(sizeof(struct null_mount), 153 M_NULLFSMNT, M_WAITOK | M_ZERO); 154 155 /* 156 * Save reference to underlying FS 157 */ 158 xmp->nullm_vfs = lowerrootvp->v_mount; 159 160 /* 161 * Save reference. Each mount also holds 162 * a reference on the root vnode. 163 */ 164 error = null_nodeget(mp, lowerrootvp, &vp); 165 /* 166 * Make sure the node alias worked 167 */ 168 if (error) { 169 free(xmp, M_NULLFSMNT); 170 return (error); 171 } 172 173 /* 174 * Keep a held reference to the root vnode. 175 * It is vrele'd in nullfs_unmount. 176 */ 177 nullm_rootvp = vp; 178 nullm_rootvp->v_vflag |= VV_ROOT; 179 xmp->nullm_rootvp = nullm_rootvp; 180 181 /* 182 * Unlock the node (either the lower or the alias) 183 */ 184 VOP_UNLOCK(vp, 0); 185 186 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) { 187 MNT_ILOCK(mp); 188 mp->mnt_flag |= MNT_LOCAL; 189 MNT_IUNLOCK(mp); 190 } 191 192 xmp->nullm_flags |= NULLM_CACHE; 193 if (vfs_getopt(mp->mnt_optnew, "nocache", NULL, NULL) == 0 || 194 (xmp->nullm_vfs->mnt_kern_flag & MNTK_NULL_NOCACHE) != 0) 195 xmp->nullm_flags &= ~NULLM_CACHE; 196 197 MNT_ILOCK(mp); 198 if ((xmp->nullm_flags & NULLM_CACHE) != 0) { 199 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & 200 (MNTK_SHARED_WRITES | MNTK_LOOKUP_SHARED | 201 MNTK_EXTENDED_SHARED); 202 } 203 mp->mnt_kern_flag |= MNTK_LOOKUP_EXCL_DOTDOT; 204 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & 205 (MNTK_USES_BCACHE | MNTK_NO_IOPF | MNTK_UNMAPPED_BUFS); 206 MNT_IUNLOCK(mp); 207 mp->mnt_data = xmp; 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); 217 218 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 struct mount *ump; 233 int error, flags; 234 235 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 236 237 if (mntflags & MNT_FORCE) 238 flags = FORCECLOSE; 239 else 240 flags = 0; 241 242 /* There is 1 extra root vnode reference (nullm_rootvp). */ 243 error = vflush(mp, 1, flags, curthread); 244 if (error) 245 return (error); 246 247 /* 248 * Finally, throw away the null_mount structure 249 */ 250 mntdata = mp->mnt_data; 251 ump = mntdata->nullm_vfs; 252 if ((mntdata->nullm_flags & NULLM_CACHE) != 0) { 253 MNT_ILOCK(ump); 254 while ((ump->mnt_kern_flag & MNTK_VGONE_UPPER) != 0) { 255 ump->mnt_kern_flag |= MNTK_VGONE_WAITER; 256 msleep(&ump->mnt_uppers, &ump->mnt_mtx, 0, "vgnupw", 0); 257 } 258 TAILQ_REMOVE(&ump->mnt_uppers, mp, mnt_upper_link); 259 MNT_IUNLOCK(ump); 260 } 261 mp->mnt_data = NULL; 262 free(mntdata, M_NULLFSMNT); 263 return (0); 264 } 265 266 static int 267 nullfs_root(mp, flags, vpp) 268 struct mount *mp; 269 int flags; 270 struct vnode **vpp; 271 { 272 struct vnode *vp; 273 274 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp, 275 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 276 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 277 278 /* 279 * Return locked reference to root. 280 */ 281 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 282 VREF(vp); 283 284 ASSERT_VOP_UNLOCKED(vp, "root vnode is locked"); 285 vn_lock(vp, flags | LK_RETRY); 286 *vpp = vp; 287 return 0; 288 } 289 290 static int 291 nullfs_quotactl(mp, cmd, uid, arg) 292 struct mount *mp; 293 int cmd; 294 uid_t uid; 295 void *arg; 296 { 297 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg); 298 } 299 300 static int 301 nullfs_statfs(mp, sbp) 302 struct mount *mp; 303 struct statfs *sbp; 304 { 305 int error; 306 struct statfs *mstat; 307 308 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 309 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 310 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 311 312 mstat = malloc(sizeof(struct statfs), M_STATFS, M_WAITOK | M_ZERO); 313 314 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, mstat); 315 if (error) { 316 free(mstat, M_STATFS); 317 return (error); 318 } 319 320 /* now copy across the "interesting" information and fake the rest */ 321 sbp->f_type = mstat->f_type; 322 sbp->f_flags = (sbp->f_flags & (MNT_RDONLY | MNT_NOEXEC | MNT_NOSUID | 323 MNT_UNION | MNT_NOSYMFOLLOW)) | (mstat->f_flags & ~MNT_ROOTFS); 324 sbp->f_bsize = mstat->f_bsize; 325 sbp->f_iosize = mstat->f_iosize; 326 sbp->f_blocks = mstat->f_blocks; 327 sbp->f_bfree = mstat->f_bfree; 328 sbp->f_bavail = mstat->f_bavail; 329 sbp->f_files = mstat->f_files; 330 sbp->f_ffree = mstat->f_ffree; 331 332 free(mstat, M_STATFS); 333 return (0); 334 } 335 336 static int 337 nullfs_sync(mp, waitfor) 338 struct mount *mp; 339 int waitfor; 340 { 341 /* 342 * XXX - Assumes no data cached at null layer. 343 */ 344 return (0); 345 } 346 347 static int 348 nullfs_vget(mp, ino, flags, vpp) 349 struct mount *mp; 350 ino_t ino; 351 int flags; 352 struct vnode **vpp; 353 { 354 int error; 355 356 KASSERT((flags & LK_TYPE_MASK) != 0, 357 ("nullfs_vget: no lock requested")); 358 359 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp); 360 if (error != 0) 361 return (error); 362 return (null_nodeget(mp, *vpp, vpp)); 363 } 364 365 static int 366 nullfs_fhtovp(mp, fidp, flags, vpp) 367 struct mount *mp; 368 struct fid *fidp; 369 int flags; 370 struct vnode **vpp; 371 { 372 int error; 373 374 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, flags, 375 vpp); 376 if (error != 0) 377 return (error); 378 return (null_nodeget(mp, *vpp, vpp)); 379 } 380 381 static int 382 nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname) 383 struct mount *mp; 384 int cmd; 385 struct vnode *filename_vp; 386 int namespace; 387 const char *attrname; 388 { 389 390 return (VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, 391 filename_vp, namespace, attrname)); 392 } 393 394 static void 395 nullfs_reclaim_lowervp(struct mount *mp, struct vnode *lowervp) 396 { 397 struct vnode *vp; 398 399 vp = null_hashget(mp, lowervp); 400 if (vp == NULL) 401 return; 402 VTONULL(vp)->null_flags |= NULLV_NOUNLOCK; 403 vgone(vp); 404 vput(vp); 405 } 406 407 static void 408 nullfs_unlink_lowervp(struct mount *mp, struct vnode *lowervp) 409 { 410 struct vnode *vp; 411 struct null_node *xp; 412 413 vp = null_hashget(mp, lowervp); 414 if (vp == NULL) 415 return; 416 xp = VTONULL(vp); 417 xp->null_flags |= NULLV_DROP | NULLV_NOUNLOCK; 418 vhold(vp); 419 vunref(vp); 420 421 if (vp->v_usecount == 0) { 422 /* 423 * If vunref() dropped the last use reference on the 424 * nullfs vnode, it must be reclaimed, and its lock 425 * was split from the lower vnode lock. Need to do 426 * extra unlock before allowing the final vdrop() to 427 * free the vnode. 428 */ 429 KASSERT((vp->v_iflag & VI_DOOMED) != 0, 430 ("not reclaimed nullfs vnode %p", vp)); 431 VOP_UNLOCK(vp, 0); 432 } else { 433 /* 434 * Otherwise, the nullfs vnode still shares the lock 435 * with the lower vnode, and must not be unlocked. 436 * Also clear the NULLV_NOUNLOCK, the flag is not 437 * relevant for future reclamations. 438 */ 439 ASSERT_VOP_ELOCKED(vp, "unlink_lowervp"); 440 KASSERT((vp->v_iflag & VI_DOOMED) == 0, 441 ("reclaimed nullfs vnode %p", vp)); 442 xp->null_flags &= ~NULLV_NOUNLOCK; 443 } 444 vdrop(vp); 445 } 446 447 static struct vfsops null_vfsops = { 448 .vfs_extattrctl = nullfs_extattrctl, 449 .vfs_fhtovp = nullfs_fhtovp, 450 .vfs_init = nullfs_init, 451 .vfs_mount = nullfs_mount, 452 .vfs_quotactl = nullfs_quotactl, 453 .vfs_root = nullfs_root, 454 .vfs_statfs = nullfs_statfs, 455 .vfs_sync = nullfs_sync, 456 .vfs_uninit = nullfs_uninit, 457 .vfs_unmount = nullfs_unmount, 458 .vfs_vget = nullfs_vget, 459 .vfs_reclaim_lowervp = nullfs_reclaim_lowervp, 460 .vfs_unlink_lowervp = nullfs_unlink_lowervp, 461 }; 462 463 VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK | VFCF_JAIL); 464