Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/fs/nullfs/null_vfsops.c
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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 = lowerrootvp->v_mount; 167 vref(lowerrootvp); 168 xmp->nullm_lowerrootvp = lowerrootvp; 169 mp->mnt_data = xmp; 170 171 /* 172 * Make sure the node alias worked. 173 */ 174 error = null_nodeget(mp, lowerrootvp, &nullm_rootvp); 175 if (error != 0) { 176 vrele(lowerrootvp); 177 free(xmp, M_NULLFSMNT); 178 return (error); 179 } 180 181 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) { 182 MNT_ILOCK(mp); 183 mp->mnt_flag |= MNT_LOCAL; 184 MNT_IUNLOCK(mp); 185 } 186 187 xmp->nullm_flags |= NULLM_CACHE; 188 if (vfs_getopt(mp->mnt_optnew, "nocache", NULL, NULL) == 0 || 189 (xmp->nullm_vfs->mnt_kern_flag & MNTK_NULL_NOCACHE) != 0) 190 xmp->nullm_flags &= ~NULLM_CACHE; 191 192 MNT_ILOCK(mp); 193 if ((xmp->nullm_flags & NULLM_CACHE) != 0) { 194 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & 195 (MNTK_SHARED_WRITES | MNTK_LOOKUP_SHARED | 196 MNTK_EXTENDED_SHARED); 197 } 198 mp->mnt_kern_flag |= MNTK_LOOKUP_EXCL_DOTDOT | MNTK_NOMSYNC; 199 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & 200 (MNTK_USES_BCACHE | MNTK_NO_IOPF | MNTK_UNMAPPED_BUFS); 201 MNT_IUNLOCK(mp); 202 vfs_getnewfsid(mp); 203 if ((xmp->nullm_flags & NULLM_CACHE) != 0) { 204 MNT_ILOCK(xmp->nullm_vfs); 205 TAILQ_INSERT_TAIL(&xmp->nullm_vfs->mnt_uppers, mp, 206 mnt_upper_link); 207 MNT_IUNLOCK(xmp->nullm_vfs); 208 } 209 210 vfs_mountedfrom(mp, target); 211 vput(nullm_rootvp); 212 213 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 214 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 215 return (0); 216 } 217 218 /* 219 * Free reference to null layer 220 */ 221 static int 222 nullfs_unmount(mp, mntflags) 223 struct mount *mp; 224 int mntflags; 225 { 226 struct null_mount *mntdata; 227 struct mount *ump; 228 int error, flags; 229 230 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 231 232 if (mntflags & MNT_FORCE) 233 flags = FORCECLOSE; 234 else 235 flags = 0; 236 237 for (;;) { 238 /* There is 1 extra root vnode reference (nullm_rootvp). */ 239 error = vflush(mp, 0, flags, curthread); 240 if (error) 241 return (error); 242 MNT_ILOCK(mp); 243 if (mp->mnt_nvnodelistsize == 0) { 244 MNT_IUNLOCK(mp); 245 break; 246 } 247 MNT_IUNLOCK(mp); 248 if ((mntflags & MNT_FORCE) == 0) 249 return (EBUSY); 250 } 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 vrele(mntdata->nullm_lowerrootvp); 267 mp->mnt_data = NULL; 268 free(mntdata, M_NULLFSMNT); 269 return (0); 270 } 271 272 static int 273 nullfs_root(mp, flags, vpp) 274 struct mount *mp; 275 int flags; 276 struct vnode **vpp; 277 { 278 struct vnode *vp; 279 struct null_mount *mntdata; 280 int error; 281 282 mntdata = MOUNTTONULLMOUNT(mp); 283 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p)\n", mp, 284 mntdata->nullm_lowerrootvp); 285 286 error = vget(mntdata->nullm_lowerrootvp, flags); 287 if (error == 0) { 288 error = null_nodeget(mp, mntdata->nullm_lowerrootvp, &vp); 289 if (error == 0) { 290 *vpp = vp; 291 } 292 } 293 return (error); 294 } 295 296 static int 297 nullfs_quotactl(mp, cmd, uid, arg) 298 struct mount *mp; 299 int cmd; 300 uid_t uid; 301 void *arg; 302 { 303 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg); 304 } 305 306 static int 307 nullfs_statfs(mp, sbp) 308 struct mount *mp; 309 struct statfs *sbp; 310 { 311 int error; 312 struct statfs *mstat; 313 314 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 315 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 316 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 317 318 mstat = malloc(sizeof(struct statfs), M_STATFS, M_WAITOK | M_ZERO); 319 320 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, mstat); 321 if (error) { 322 free(mstat, M_STATFS); 323 return (error); 324 } 325 326 /* now copy across the "interesting" information and fake the rest */ 327 sbp->f_type = mstat->f_type; 328 sbp->f_flags = (sbp->f_flags & (MNT_RDONLY | MNT_NOEXEC | MNT_NOSUID | 329 MNT_UNION | MNT_NOSYMFOLLOW | MNT_AUTOMOUNTED)) | 330 (mstat->f_flags & ~(MNT_ROOTFS | MNT_AUTOMOUNTED)); 331 sbp->f_bsize = mstat->f_bsize; 332 sbp->f_iosize = mstat->f_iosize; 333 sbp->f_blocks = mstat->f_blocks; 334 sbp->f_bfree = mstat->f_bfree; 335 sbp->f_bavail = mstat->f_bavail; 336 sbp->f_files = mstat->f_files; 337 sbp->f_ffree = mstat->f_ffree; 338 339 free(mstat, M_STATFS); 340 return (0); 341 } 342 343 static int 344 nullfs_sync(mp, waitfor) 345 struct mount *mp; 346 int waitfor; 347 { 348 /* 349 * XXX - Assumes no data cached at null layer. 350 */ 351 return (0); 352 } 353 354 static int 355 nullfs_vget(mp, ino, flags, vpp) 356 struct mount *mp; 357 ino_t ino; 358 int flags; 359 struct vnode **vpp; 360 { 361 int error; 362 363 KASSERT((flags & LK_TYPE_MASK) != 0, 364 ("nullfs_vget: no lock requested")); 365 366 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp); 367 if (error != 0) 368 return (error); 369 return (null_nodeget(mp, *vpp, vpp)); 370 } 371 372 static int 373 nullfs_fhtovp(mp, fidp, flags, vpp) 374 struct mount *mp; 375 struct fid *fidp; 376 int flags; 377 struct vnode **vpp; 378 { 379 int error; 380 381 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, flags, 382 vpp); 383 if (error != 0) 384 return (error); 385 return (null_nodeget(mp, *vpp, vpp)); 386 } 387 388 static int 389 nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname) 390 struct mount *mp; 391 int cmd; 392 struct vnode *filename_vp; 393 int namespace; 394 const char *attrname; 395 { 396 397 return (VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, 398 filename_vp, namespace, attrname)); 399 } 400 401 static void 402 nullfs_reclaim_lowervp(struct mount *mp, struct vnode *lowervp) 403 { 404 struct vnode *vp; 405 406 vp = null_hashget(mp, lowervp); 407 if (vp == NULL) 408 return; 409 VTONULL(vp)->null_flags |= NULLV_NOUNLOCK; 410 vgone(vp); 411 vput(vp); 412 } 413 414 static void 415 nullfs_unlink_lowervp(struct mount *mp, struct vnode *lowervp) 416 { 417 struct vnode *vp; 418 struct null_node *xp; 419 420 vp = null_hashget(mp, lowervp); 421 if (vp == NULL) 422 return; 423 xp = VTONULL(vp); 424 xp->null_flags |= NULLV_DROP | NULLV_NOUNLOCK; 425 vhold(vp); 426 vunref(vp); 427 428 if (vp->v_usecount == 0) { 429 /* 430 * If vunref() dropped the last use reference on the 431 * nullfs vnode, it must be reclaimed, and its lock 432 * was split from the lower vnode lock. Need to do 433 * extra unlock before allowing the final vdrop() to 434 * free the vnode. 435 */ 436 KASSERT(VN_IS_DOOMED(vp), 437 ("not reclaimed nullfs vnode %p", vp)); 438 VOP_UNLOCK(vp); 439 } else { 440 /* 441 * Otherwise, the nullfs vnode still shares the lock 442 * with the lower vnode, and must not be unlocked. 443 * Also clear the NULLV_NOUNLOCK, the flag is not 444 * relevant for future reclamations. 445 */ 446 ASSERT_VOP_ELOCKED(vp, "unlink_lowervp"); 447 KASSERT(!VN_IS_DOOMED(vp), 448 ("reclaimed nullfs vnode %p", vp)); 449 xp->null_flags &= ~NULLV_NOUNLOCK; 450 } 451 vdrop(vp); 452 } 453 454 static struct vfsops null_vfsops = { 455 .vfs_extattrctl = nullfs_extattrctl, 456 .vfs_fhtovp = nullfs_fhtovp, 457 .vfs_init = nullfs_init, 458 .vfs_mount = nullfs_mount, 459 .vfs_quotactl = nullfs_quotactl, 460 .vfs_root = nullfs_root, 461 .vfs_statfs = nullfs_statfs, 462 .vfs_sync = nullfs_sync, 463 .vfs_uninit = nullfs_uninit, 464 .vfs_unmount = nullfs_unmount, 465 .vfs_vget = nullfs_vget, 466 .vfs_reclaim_lowervp = nullfs_reclaim_lowervp, 467 .vfs_unlink_lowervp = nullfs_unlink_lowervp, 468 }; 469 470 VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK | VFCF_JAIL);
Cache object: 903083b493d2c2d7fcb0e3bb27f0228a
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