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