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, "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 pointer to underlying FS and the reference to the 162 * lower root vnode. 163 */ 164 xmp->nullm_vfs = lowerrootvp->v_mount; 165 vref(lowerrootvp); 166 xmp->nullm_lowerrootvp = lowerrootvp; 167 mp->mnt_data = xmp; 168 169 /* 170 * Make sure the node alias worked. 171 */ 172 error = null_nodeget(mp, lowerrootvp, &nullm_rootvp); 173 if (error != 0) { 174 vrele(lowerrootvp); 175 free(xmp, M_NULLFSMNT); 176 return (error); 177 } 178 179 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) { 180 MNT_ILOCK(mp); 181 mp->mnt_flag |= MNT_LOCAL; 182 MNT_IUNLOCK(mp); 183 } 184 185 xmp->nullm_flags |= NULLM_CACHE; 186 if (vfs_getopt(mp->mnt_optnew, "nocache", NULL, NULL) == 0 || 187 (xmp->nullm_vfs->mnt_kern_flag & MNTK_NULL_NOCACHE) != 0) 188 xmp->nullm_flags &= ~NULLM_CACHE; 189 190 MNT_ILOCK(mp); 191 if ((xmp->nullm_flags & NULLM_CACHE) != 0) { 192 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & 193 (MNTK_SHARED_WRITES | MNTK_LOOKUP_SHARED | 194 MNTK_EXTENDED_SHARED); 195 } 196 mp->mnt_kern_flag |= MNTK_LOOKUP_EXCL_DOTDOT; 197 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & 198 (MNTK_USES_BCACHE | MNTK_NO_IOPF | MNTK_UNMAPPED_BUFS); 199 MNT_IUNLOCK(mp); 200 vfs_getnewfsid(mp); 201 if ((xmp->nullm_flags & NULLM_CACHE) != 0) { 202 MNT_ILOCK(xmp->nullm_vfs); 203 TAILQ_INSERT_TAIL(&xmp->nullm_vfs->mnt_uppers, mp, 204 mnt_upper_link); 205 MNT_IUNLOCK(xmp->nullm_vfs); 206 } 207 208 vfs_mountedfrom(mp, target); 209 vput(nullm_rootvp); 210 211 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 212 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 213 return (0); 214 } 215 216 /* 217 * Free reference to null layer 218 */ 219 static int 220 nullfs_unmount(mp, mntflags) 221 struct mount *mp; 222 int mntflags; 223 { 224 struct null_mount *mntdata; 225 struct mount *ump; 226 int error, flags; 227 228 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 229 230 if (mntflags & MNT_FORCE) 231 flags = FORCECLOSE; 232 else 233 flags = 0; 234 235 for (;;) { 236 /* There is 1 extra root vnode reference (nullm_rootvp). */ 237 error = vflush(mp, 0, flags, curthread); 238 if (error) 239 return (error); 240 MNT_ILOCK(mp); 241 if (mp->mnt_nvnodelistsize == 0) { 242 MNT_IUNLOCK(mp); 243 break; 244 } 245 MNT_IUNLOCK(mp); 246 if ((mntflags & MNT_FORCE) == 0) 247 return (EBUSY); 248 } 249 250 /* 251 * Finally, throw away the null_mount structure 252 */ 253 mntdata = mp->mnt_data; 254 ump = mntdata->nullm_vfs; 255 if ((mntdata->nullm_flags & NULLM_CACHE) != 0) { 256 MNT_ILOCK(ump); 257 while ((ump->mnt_kern_flag & MNTK_VGONE_UPPER) != 0) { 258 ump->mnt_kern_flag |= MNTK_VGONE_WAITER; 259 msleep(&ump->mnt_uppers, &ump->mnt_mtx, 0, "vgnupw", 0); 260 } 261 TAILQ_REMOVE(&ump->mnt_uppers, mp, mnt_upper_link); 262 MNT_IUNLOCK(ump); 263 } 264 vrele(mntdata->nullm_lowerrootvp); 265 mp->mnt_data = NULL; 266 free(mntdata, M_NULLFSMNT); 267 return (0); 268 } 269 270 static int 271 nullfs_root(mp, flags, vpp) 272 struct mount *mp; 273 int flags; 274 struct vnode **vpp; 275 { 276 struct vnode *vp; 277 struct null_mount *mntdata; 278 int error; 279 280 mntdata = MOUNTTONULLMOUNT(mp); 281 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p)\n", mp, 282 mntdata->nullm_lowerrootvp); 283 284 error = vget(mntdata->nullm_lowerrootvp, (flags & ~LK_TYPE_MASK) | 285 LK_EXCLUSIVE, curthread); 286 if (error == 0) { 287 error = null_nodeget(mp, mntdata->nullm_lowerrootvp, &vp); 288 if (error == 0) { 289 if ((flags & LK_TYPE_MASK) == LK_SHARED) 290 vn_lock(vp, LK_DOWNGRADE | LK_RETRY); 291 *vpp = vp; 292 } 293 } 294 return (error); 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 mstat = malloc(sizeof(struct statfs), M_STATFS, M_WAITOK | M_ZERO); 320 321 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, mstat); 322 if (error) { 323 free(mstat, M_STATFS); 324 return (error); 325 } 326 327 /* now copy across the "interesting" information and fake the rest */ 328 sbp->f_type = mstat->f_type; 329 sbp->f_flags = (sbp->f_flags & (MNT_RDONLY | MNT_NOEXEC | MNT_NOSUID | 330 MNT_UNION | MNT_NOSYMFOLLOW | MNT_AUTOMOUNTED)) | 331 (mstat->f_flags & ~(MNT_ROOTFS | MNT_AUTOMOUNTED)); 332 sbp->f_bsize = mstat->f_bsize; 333 sbp->f_iosize = mstat->f_iosize; 334 sbp->f_blocks = mstat->f_blocks; 335 sbp->f_bfree = mstat->f_bfree; 336 sbp->f_bavail = mstat->f_bavail; 337 sbp->f_files = mstat->f_files; 338 sbp->f_ffree = mstat->f_ffree; 339 340 free(mstat, M_STATFS); 341 return (0); 342 } 343 344 static int 345 nullfs_sync(mp, waitfor) 346 struct mount *mp; 347 int waitfor; 348 { 349 /* 350 * XXX - Assumes no data cached at null layer. 351 */ 352 return (0); 353 } 354 355 static int 356 nullfs_vget(mp, ino, flags, vpp) 357 struct mount *mp; 358 ino_t ino; 359 int flags; 360 struct vnode **vpp; 361 { 362 int error; 363 364 KASSERT((flags & LK_TYPE_MASK) != 0, 365 ("nullfs_vget: no lock requested")); 366 367 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp); 368 if (error != 0) 369 return (error); 370 return (null_nodeget(mp, *vpp, vpp)); 371 } 372 373 static int 374 nullfs_fhtovp(mp, fidp, flags, vpp) 375 struct mount *mp; 376 struct fid *fidp; 377 int flags; 378 struct vnode **vpp; 379 { 380 int error; 381 382 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, flags, 383 vpp); 384 if (error != 0) 385 return (error); 386 return (null_nodeget(mp, *vpp, vpp)); 387 } 388 389 static int 390 nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname) 391 struct mount *mp; 392 int cmd; 393 struct vnode *filename_vp; 394 int namespace; 395 const char *attrname; 396 { 397 398 return (VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, 399 filename_vp, namespace, attrname)); 400 } 401 402 static void 403 nullfs_reclaim_lowervp(struct mount *mp, struct vnode *lowervp) 404 { 405 struct vnode *vp; 406 407 vp = null_hashget(mp, lowervp); 408 if (vp == NULL) 409 return; 410 VTONULL(vp)->null_flags |= NULLV_NOUNLOCK; 411 vgone(vp); 412 vput(vp); 413 } 414 415 static void 416 nullfs_unlink_lowervp(struct mount *mp, struct vnode *lowervp) 417 { 418 struct vnode *vp; 419 struct null_node *xp; 420 421 vp = null_hashget(mp, lowervp); 422 if (vp == NULL) 423 return; 424 xp = VTONULL(vp); 425 xp->null_flags |= NULLV_DROP | NULLV_NOUNLOCK; 426 vhold(vp); 427 vunref(vp); 428 429 if (vp->v_usecount == 0) { 430 /* 431 * If vunref() dropped the last use reference on the 432 * nullfs vnode, it must be reclaimed, and its lock 433 * was split from the lower vnode lock. Need to do 434 * extra unlock before allowing the final vdrop() to 435 * free the vnode. 436 */ 437 KASSERT((vp->v_iflag & VI_DOOMED) != 0, 438 ("not reclaimed nullfs vnode %p", vp)); 439 VOP_UNLOCK(vp, 0); 440 } else { 441 /* 442 * Otherwise, the nullfs vnode still shares the lock 443 * with the lower vnode, and must not be unlocked. 444 * Also clear the NULLV_NOUNLOCK, the flag is not 445 * relevant for future reclamations. 446 */ 447 ASSERT_VOP_ELOCKED(vp, "unlink_lowervp"); 448 KASSERT((vp->v_iflag & VI_DOOMED) == 0, 449 ("reclaimed nullfs vnode %p", vp)); 450 xp->null_flags &= ~NULLV_NOUNLOCK; 451 } 452 vdrop(vp); 453 } 454 455 static struct vfsops null_vfsops = { 456 .vfs_extattrctl = nullfs_extattrctl, 457 .vfs_fhtovp = nullfs_fhtovp, 458 .vfs_init = nullfs_init, 459 .vfs_mount = nullfs_mount, 460 .vfs_quotactl = nullfs_quotactl, 461 .vfs_root = nullfs_root, 462 .vfs_statfs = nullfs_statfs, 463 .vfs_sync = nullfs_sync, 464 .vfs_uninit = nullfs_uninit, 465 .vfs_unmount = nullfs_unmount, 466 .vfs_vget = nullfs_vget, 467 .vfs_reclaim_lowervp = nullfs_reclaim_lowervp, 468 .vfs_unlink_lowervp = nullfs_unlink_lowervp, 469 }; 470 471 VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK | VFCF_JAIL);
Cache object: ab29279a65b421e8840ec190f7c38521
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