1 /* 2 * Copyright (c) 1992, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * John Heidemann of the UCLA Ficus project. 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 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)null_vnops.c 8.6 (Berkeley) 5/27/95 37 * 38 * Ancestors: 39 * @(#)lofs_vnops.c 1.2 (Berkeley) 6/18/92 40 * $FreeBSD: src/sys/miscfs/nullfs/null_vnops.c,v 1.38.2.6 2002/07/31 00:32:28 semenu Exp $ 41 * $DragonFly: src/sys/vfs/nullfs/null_vnops.c,v 1.11 2004/04/24 04:32:04 drhodus Exp $ 42 * ...and... 43 * @(#)null_vnodeops.c 1.20 92/07/07 UCLA Ficus project 44 * 45 * $FreeBSD: src/sys/miscfs/nullfs/null_vnops.c,v 1.38.2.6 2002/07/31 00:32:28 semenu Exp $ 46 */ 47 48 /* 49 * Null Layer 50 * 51 * (See mount_null(8) for more information.) 52 * 53 * The null layer duplicates a portion of the file system 54 * name space under a new name. In this respect, it is 55 * similar to the loopback file system. It differs from 56 * the loopback fs in two respects: it is implemented using 57 * a stackable layers techniques, and its "null-node"s stack above 58 * all lower-layer vnodes, not just over directory vnodes. 59 * 60 * The null layer has two purposes. First, it serves as a demonstration 61 * of layering by proving a layer which does nothing. (It actually 62 * does everything the loopback file system does, which is slightly 63 * more than nothing.) Second, the null layer can serve as a prototype 64 * layer. Since it provides all necessary layer framework, 65 * new file system layers can be created very easily be starting 66 * with a null layer. 67 * 68 * The remainder of this man page examines the null layer as a basis 69 * for constructing new layers. 70 * 71 * 72 * INSTANTIATING NEW NULL LAYERS 73 * 74 * New null layers are created with mount_null(8). 75 * Mount_null(8) takes two arguments, the pathname 76 * of the lower vfs (target-pn) and the pathname where the null 77 * layer will appear in the namespace (alias-pn). After 78 * the null layer is put into place, the contents 79 * of target-pn subtree will be aliased under alias-pn. 80 * 81 * 82 * OPERATION OF A NULL LAYER 83 * 84 * The null layer is the minimum file system layer, 85 * simply bypassing all possible operations to the lower layer 86 * for processing there. The majority of its activity centers 87 * on the bypass routine, through which nearly all vnode operations 88 * pass. 89 * 90 * The bypass routine accepts arbitrary vnode operations for 91 * handling by the lower layer. It begins by examing vnode 92 * operation arguments and replacing any null-nodes by their 93 * lower-layer equivlants. It then invokes the operation 94 * on the lower layer. Finally, it replaces the null-nodes 95 * in the arguments and, if a vnode is return by the operation, 96 * stacks a null-node on top of the returned vnode. 97 * 98 * Although bypass handles most operations, vop_getattr, vop_lock, 99 * vop_unlock, vop_inactive, vop_reclaim, and vop_print are not 100 * bypassed. Vop_getattr must change the fsid being returned. 101 * Vop_lock and vop_unlock must handle any locking for the 102 * current vnode as well as pass the lock request down. 103 * Vop_inactive and vop_reclaim are not bypassed so that 104 * they can handle freeing null-layer specific data. Vop_print 105 * is not bypassed to avoid excessive debugging information. 106 * Also, certain vnode operations change the locking state within 107 * the operation (create, mknod, remove, link, rename, mkdir, rmdir, 108 * and symlink). Ideally these operations should not change the 109 * lock state, but should be changed to let the caller of the 110 * function unlock them. Otherwise all intermediate vnode layers 111 * (such as union, umapfs, etc) must catch these functions to do 112 * the necessary locking at their layer. 113 * 114 * 115 * INSTANTIATING VNODE STACKS 116 * 117 * Mounting associates the null layer with a lower layer, 118 * effect stacking two VFSes. Vnode stacks are instead 119 * created on demand as files are accessed. 120 * 121 * The initial mount creates a single vnode stack for the 122 * root of the new null layer. All other vnode stacks 123 * are created as a result of vnode operations on 124 * this or other null vnode stacks. 125 * 126 * New vnode stacks come into existance as a result of 127 * an operation which returns a vnode. 128 * The bypass routine stacks a null-node above the new 129 * vnode before returning it to the caller. 130 * 131 * For example, imagine mounting a null layer with 132 * "mount_null /usr/include /dev/layer/null". 133 * Changing directory to /dev/layer/null will assign 134 * the root null-node (which was created when the null layer was mounted). 135 * Now consider opening "sys". A vop_lookup would be 136 * done on the root null-node. This operation would bypass through 137 * to the lower layer which would return a vnode representing 138 * the UFS "sys". Null_bypass then builds a null-node 139 * aliasing the UFS "sys" and returns this to the caller. 140 * Later operations on the null-node "sys" will repeat this 141 * process when constructing other vnode stacks. 142 * 143 * 144 * CREATING OTHER FILE SYSTEM LAYERS 145 * 146 * One of the easiest ways to construct new file system layers is to make 147 * a copy of the null layer, rename all files and variables, and 148 * then begin modifing the copy. Sed can be used to easily rename 149 * all variables. 150 * 151 * The umap layer is an example of a layer descended from the 152 * null layer. 153 * 154 * 155 * INVOKING OPERATIONS ON LOWER LAYERS 156 * 157 * There are two techniques to invoke operations on a lower layer 158 * when the operation cannot be completely bypassed. Each method 159 * is appropriate in different situations. In both cases, 160 * it is the responsibility of the aliasing layer to make 161 * the operation arguments "correct" for the lower layer 162 * by mapping an vnode arguments to the lower layer. 163 * 164 * The first approach is to call the aliasing layer's bypass routine. 165 * This method is most suitable when you wish to invoke the operation 166 * currently being handled on the lower layer. It has the advantage 167 * that the bypass routine already must do argument mapping. 168 * An example of this is null_getattrs in the null layer. 169 * 170 * A second approach is to directly invoke vnode operations on 171 * the lower layer with the VOP_OPERATIONNAME interface. 172 * The advantage of this method is that it is easy to invoke 173 * arbitrary operations on the lower layer. The disadvantage 174 * is that vnode arguments must be manualy mapped. 175 * 176 */ 177 178 #include <sys/param.h> 179 #include <sys/systm.h> 180 #include <sys/kernel.h> 181 #include <sys/sysctl.h> 182 #include <sys/vnode.h> 183 #include <sys/mount.h> 184 #include <sys/proc.h> 185 #include <sys/namei.h> 186 #include <sys/malloc.h> 187 #include <sys/buf.h> 188 #include "null.h" 189 190 static int null_bug_bypass = 0; /* for debugging: enables bypass printf'ing */ 191 SYSCTL_INT(_debug, OID_AUTO, nullfs_bug_bypass, CTLFLAG_RW, 192 &null_bug_bypass, 0, ""); 193 194 static int null_access(struct vop_access_args *ap); 195 static int null_createvobject(struct vop_createvobject_args *ap); 196 static int null_destroyvobject(struct vop_destroyvobject_args *ap); 197 static int null_getattr(struct vop_getattr_args *ap); 198 static int null_getvobject(struct vop_getvobject_args *ap); 199 static int null_inactive(struct vop_inactive_args *ap); 200 static int null_islocked(struct vop_islocked_args *ap); 201 static int null_lock(struct vop_lock_args *ap); 202 static int null_lookup(struct vop_lookup_args *ap); 203 static int null_open(struct vop_open_args *ap); 204 static int null_print(struct vop_print_args *ap); 205 static int null_reclaim(struct vop_reclaim_args *ap); 206 static int null_rename(struct vop_rename_args *ap); 207 static int null_setattr(struct vop_setattr_args *ap); 208 static int null_unlock(struct vop_unlock_args *ap); 209 210 /* 211 * This is the 10-Apr-92 bypass routine. 212 * This version has been optimized for speed, throwing away some 213 * safety checks. It should still always work, but it's not as 214 * robust to programmer errors. 215 * 216 * In general, we map all vnodes going down and unmap them on the way back. 217 * As an exception to this, vnodes can be marked "unmapped" by setting 218 * the Nth bit in operation's vdesc_flags. 219 * 220 * Also, some BSD vnode operations have the side effect of vrele'ing 221 * their arguments. With stacking, the reference counts are held 222 * by the upper node, not the lower one, so we must handle these 223 * side-effects here. This is not of concern in Sun-derived systems 224 * since there are no such side-effects. 225 * 226 * This makes the following assumptions: 227 * - only one returned vpp 228 * - no INOUT vpp's (Sun's vop_open has one of these) 229 * - the vnode operation vector of the first vnode should be used 230 * to determine what implementation of the op should be invoked 231 * - all mapped vnodes are of our vnode-type (NEEDSWORK: 232 * problems on rmdir'ing mount points and renaming?) 233 * 234 * null_bypass(struct vnodeop_desc *a_desc, ...) 235 */ 236 int 237 null_bypass(struct vop_generic_args *ap) 238 { 239 register struct vnode **this_vp_p; 240 int error; 241 struct vnode *old_vps[VDESC_MAX_VPS]; 242 struct vnode **vps_p[VDESC_MAX_VPS]; 243 struct vnode ***vppp; 244 struct vnodeop_desc *descp = ap->a_desc; 245 int reles, i; 246 247 if (null_bug_bypass) 248 printf ("null_bypass: %s\n", descp->vdesc_name); 249 250 #ifdef DIAGNOSTIC 251 /* 252 * We require at least one vp. 253 */ 254 if (descp->vdesc_vp_offsets == NULL || 255 descp->vdesc_vp_offsets[0] == VDESC_NO_OFFSET) 256 panic ("null_bypass: no vp's in map"); 257 #endif 258 259 /* 260 * Map the vnodes going in. 261 * Later, we'll invoke the operation based on 262 * the first mapped vnode's operation vector. 263 */ 264 reles = descp->vdesc_flags; 265 for (i = 0; i < VDESC_MAX_VPS; reles >>= 1, i++) { 266 if (descp->vdesc_vp_offsets[i] == VDESC_NO_OFFSET) 267 break; /* bail out at end of list */ 268 vps_p[i] = this_vp_p = 269 VOPARG_OFFSETTO(struct vnode**,descp->vdesc_vp_offsets[i],ap); 270 /* 271 * We're not guaranteed that any but the first vnode 272 * are of our type. Check for and don't map any 273 * that aren't. (We must always map first vp or vclean fails.) 274 */ 275 if (i && (*this_vp_p == NULLVP || 276 (*this_vp_p)->v_op != null_vnodeop_p)) { 277 old_vps[i] = NULLVP; 278 } else { 279 old_vps[i] = *this_vp_p; 280 *(vps_p[i]) = NULLVPTOLOWERVP(*this_vp_p); 281 /* 282 * XXX - Several operations have the side effect 283 * of vrele'ing their vp's. We must account for 284 * that. (This should go away in the future.) 285 */ 286 if (reles & VDESC_VP0_WILLRELE) 287 vref(*this_vp_p); 288 } 289 290 } 291 292 /* 293 * Call the operation on the lower layer 294 * with the modified argument structure. 295 */ 296 if (vps_p[0] && *vps_p[0]) 297 error = VCALL(*(vps_p[0]), descp->vdesc_offset, ap); 298 else { 299 printf("null_bypass: no map for %s\n", descp->vdesc_name); 300 error = EINVAL; 301 } 302 303 /* 304 * Maintain the illusion of call-by-value 305 * by restoring vnodes in the argument structure 306 * to their original value. 307 */ 308 reles = descp->vdesc_flags; 309 for (i = 0; i < VDESC_MAX_VPS; reles >>= 1, i++) { 310 if (descp->vdesc_vp_offsets[i] == VDESC_NO_OFFSET) 311 break; /* bail out at end of list */ 312 if (old_vps[i]) { 313 *(vps_p[i]) = old_vps[i]; 314 #if 0 315 if (reles & VDESC_VP0_WILLUNLOCK) 316 VOP_UNLOCK(*(vps_p[i]), NULL, LK_THISLAYER, curproc); 317 #endif 318 if (reles & VDESC_VP0_WILLRELE) 319 vrele(*(vps_p[i])); 320 } 321 } 322 323 /* 324 * Map the possible out-going vpp 325 * (Assumes that the lower layer always returns 326 * a vref'ed vpp unless it gets an error.) 327 */ 328 if (descp->vdesc_vpp_offset != VDESC_NO_OFFSET && 329 !(descp->vdesc_flags & VDESC_NOMAP_VPP) && 330 !error) { 331 /* 332 * XXX - even though some ops have vpp returned vp's, 333 * several ops actually vrele this before returning. 334 * We must avoid these ops. 335 * (This should go away when these ops are regularized.) 336 */ 337 if (descp->vdesc_flags & VDESC_VPP_WILLRELE) 338 goto out; 339 vppp = VOPARG_OFFSETTO(struct vnode***, 340 descp->vdesc_vpp_offset,ap); 341 if (*vppp) 342 error = null_node_create(old_vps[0]->v_mount, **vppp, *vppp); 343 } 344 345 out: 346 return (error); 347 } 348 349 /* 350 * We have to carry on the locking protocol on the null layer vnodes 351 * as we progress through the tree. We also have to enforce read-only 352 * if this layer is mounted read-only. 353 * 354 * null_lookup(struct vnode *a_dvp, struct vnode **a_vpp, 355 * struct componentname *a_cnp) 356 */ 357 static int 358 null_lookup(struct vop_lookup_args *ap) 359 { 360 struct componentname *cnp = ap->a_cnp; 361 struct vnode *dvp = ap->a_dvp; 362 struct thread *td = cnp->cn_td; 363 int flags = cnp->cn_flags; 364 struct vnode *vp, *ldvp, *lvp; 365 int error; 366 367 if ((flags & CNP_ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 368 (cnp->cn_nameiop == NAMEI_DELETE || cnp->cn_nameiop == NAMEI_RENAME)) 369 return (EROFS); 370 /* 371 * Although it is possible to call null_bypass(), we'll do 372 * a direct call to reduce overhead 373 */ 374 ldvp = NULLVPTOLOWERVP(dvp); 375 vp = lvp = NULL; 376 error = VOP_LOOKUP(ldvp, NCPNULL, &lvp, NCPPNULL, cnp); 377 if (error == EJUSTRETURN && (flags & CNP_ISLASTCN) && 378 (dvp->v_mount->mnt_flag & MNT_RDONLY) && 379 (cnp->cn_nameiop == NAMEI_CREATE || cnp->cn_nameiop == NAMEI_RENAME)) 380 error = EROFS; 381 382 /* 383 * Rely only on the PDIRUNLOCK flag which should be carefully 384 * tracked by underlying filesystem. 385 */ 386 if (cnp->cn_flags & CNP_PDIRUNLOCK) 387 VOP_UNLOCK(dvp, NULL, LK_THISLAYER, td); 388 if ((error == 0 || error == EJUSTRETURN) && lvp != NULL) { 389 if (ldvp == lvp) { 390 *ap->a_vpp = dvp; 391 vref(dvp); 392 vrele(lvp); 393 } else { 394 error = null_node_create(dvp->v_mount, lvp, &vp); 395 if (error == 0) 396 *ap->a_vpp = vp; 397 } 398 } 399 return (error); 400 } 401 402 /* 403 * Setattr call. Disallow write attempts if the layer is mounted read-only. 404 * 405 * null_setattr(struct vnodeop_desc *a_desc, struct vnode *a_vp, 406 * struct vattr *a_vap, struct ucred *a_cred, 407 * struct thread *a_td) 408 */ 409 int 410 null_setattr(struct vop_setattr_args *ap) 411 { 412 struct vnode *vp = ap->a_vp; 413 struct vattr *vap = ap->a_vap; 414 415 if ((vap->va_flags != VNOVAL || vap->va_uid != (uid_t)VNOVAL || 416 vap->va_gid != (gid_t)VNOVAL || vap->va_atime.tv_sec != VNOVAL || 417 vap->va_mtime.tv_sec != VNOVAL || vap->va_mode != (mode_t)VNOVAL) && 418 (vp->v_mount->mnt_flag & MNT_RDONLY)) 419 return (EROFS); 420 if (vap->va_size != VNOVAL) { 421 switch (vp->v_type) { 422 case VDIR: 423 return (EISDIR); 424 case VCHR: 425 case VBLK: 426 case VSOCK: 427 case VFIFO: 428 if (vap->va_flags != VNOVAL) 429 return (EOPNOTSUPP); 430 return (0); 431 case VREG: 432 case VLNK: 433 default: 434 /* 435 * Disallow write attempts if the filesystem is 436 * mounted read-only. 437 */ 438 if (vp->v_mount->mnt_flag & MNT_RDONLY) 439 return (EROFS); 440 } 441 } 442 443 return (null_bypass((struct vop_generic_args *)ap)); 444 } 445 446 /* 447 * We handle getattr only to change the fsid. 448 * 449 * null_getattr(struct vnode *a_vp, struct vattr *a_vap, struct ucred *a_cred, 450 * struct thread *a_td) 451 */ 452 static int 453 null_getattr(struct vop_getattr_args *ap) 454 { 455 int error; 456 457 if ((error = null_bypass((struct vop_generic_args *)ap)) != 0) 458 return (error); 459 460 ap->a_vap->va_fsid = ap->a_vp->v_mount->mnt_stat.f_fsid.val[0]; 461 return (0); 462 } 463 464 /* 465 * Handle to disallow write access if mounted read-only. 466 * 467 * null_access(struct vnode *a_vp, int a_mode, struct ucred *a_cred, 468 * struct thread *a_td) 469 */ 470 static int 471 null_access(struct vop_access_args *ap) 472 { 473 struct vnode *vp = ap->a_vp; 474 mode_t mode = ap->a_mode; 475 476 /* 477 * Disallow write attempts on read-only layers; 478 * unless the file is a socket, fifo, or a block or 479 * character device resident on the file system. 480 */ 481 if (mode & VWRITE) { 482 switch (vp->v_type) { 483 case VDIR: 484 case VLNK: 485 case VREG: 486 if (vp->v_mount->mnt_flag & MNT_RDONLY) 487 return (EROFS); 488 break; 489 default: 490 break; 491 } 492 } 493 return (null_bypass((struct vop_generic_args *)ap)); 494 } 495 496 /* 497 * We must handle open to be able to catch MNT_NODEV and friends. 498 * 499 * null_open(struct vnode *a_vp, int a_mode, struct ucred *a_cred, 500 * struct thread *a_td) 501 */ 502 static int 503 null_open(struct vop_open_args *ap) 504 { 505 struct vnode *vp = ap->a_vp; 506 struct vnode *lvp = NULLVPTOLOWERVP(ap->a_vp); 507 508 if ((vp->v_mount->mnt_flag & MNT_NODEV) && 509 (lvp->v_type == VBLK || lvp->v_type == VCHR)) 510 return ENXIO; 511 512 return (null_bypass((struct vop_generic_args *)ap)); 513 } 514 515 /* 516 * We handle this to eliminate null FS to lower FS 517 * file moving. Don't know why we don't allow this, 518 * possibly we should. 519 * 520 * null_rename(struct vnode *a_fdvp, struct vnode *a_fvp, 521 * struct componentname *a_fcnp, struct vnode *a_tdvp, 522 * struct vnode *a_tvp, struct componentname *a_tcnp) 523 */ 524 static int 525 null_rename(struct vop_rename_args *ap) 526 { 527 struct vnode *tdvp = ap->a_tdvp; 528 struct vnode *fvp = ap->a_fvp; 529 struct vnode *fdvp = ap->a_fdvp; 530 struct vnode *tvp = ap->a_tvp; 531 532 /* Check for cross-device rename. */ 533 if ((fvp->v_mount != tdvp->v_mount) || 534 (tvp && (fvp->v_mount != tvp->v_mount))) { 535 if (tdvp == tvp) 536 vrele(tdvp); 537 else 538 vput(tdvp); 539 if (tvp) 540 vput(tvp); 541 vrele(fdvp); 542 vrele(fvp); 543 return (EXDEV); 544 } 545 546 return (null_bypass((struct vop_generic_args *)ap)); 547 } 548 549 /* 550 * We need to process our own vnode lock and then clear the 551 * interlock flag as it applies only to our vnode, not the 552 * vnodes below us on the stack. 553 * 554 * null_lock(struct vnode *a_vp, lwkt_tokref_t a_vlock, int a_flags, 555 * struct thread *a_td) 556 */ 557 static int 558 null_lock(struct vop_lock_args *ap) 559 { 560 struct vnode *vp = ap->a_vp; 561 int flags = ap->a_flags; 562 struct null_node *np = VTONULL(vp); 563 struct vnode *lvp; 564 int error; 565 566 if (flags & LK_THISLAYER) { 567 if (vp->v_vnlock != NULL) { 568 /* lock is shared across layers */ 569 if (flags & LK_INTERLOCK) 570 lwkt_reltoken(ap->a_vlock); 571 return 0; 572 } 573 error = lockmgr(&np->null_lock, flags & ~LK_THISLAYER, 574 ap->a_vlock, ap->a_td); 575 return (error); 576 } 577 578 if (vp->v_vnlock != NULL) { 579 /* 580 * The lower level has exported a struct lock to us. Use 581 * it so that all vnodes in the stack lock and unlock 582 * simultaneously. Note: we don't DRAIN the lock as DRAIN 583 * decommissions the lock - just because our vnode is 584 * going away doesn't mean the struct lock below us is. 585 * LK_EXCLUSIVE is fine. 586 */ 587 if ((flags & LK_TYPE_MASK) == LK_DRAIN) { 588 NULLFSDEBUG("null_lock: avoiding LK_DRAIN\n"); 589 return(lockmgr(vp->v_vnlock, 590 (flags & ~LK_TYPE_MASK) | LK_EXCLUSIVE, 591 ap->a_vlock, ap->a_td)); 592 } 593 return(lockmgr(vp->v_vnlock, flags, ap->a_vlock, ap->a_td)); 594 } 595 /* 596 * To prevent race conditions involving doing a lookup 597 * on "..", we have to lock the lower node, then lock our 598 * node. Most of the time it won't matter that we lock our 599 * node (as any locking would need the lower one locked 600 * first). But we can LK_DRAIN the upper lock as a step 601 * towards decomissioning it. 602 */ 603 lvp = NULLVPTOLOWERVP(vp); 604 if (lvp == NULL) 605 return (lockmgr(&np->null_lock, flags, ap->a_vlock, ap->a_td)); 606 if (flags & LK_INTERLOCK) { 607 VI_UNLOCK(ap->a_vlock, vp); 608 flags &= ~LK_INTERLOCK; 609 } 610 if ((flags & LK_TYPE_MASK) == LK_DRAIN) { 611 error = VOP_LOCK(lvp, ap->a_vlock, 612 (flags & ~LK_TYPE_MASK) | LK_EXCLUSIVE, ap->a_td); 613 } else 614 error = VOP_LOCK(lvp, ap->a_vlock, flags, ap->a_td); 615 if (error) 616 return (error); 617 error = lockmgr(&np->null_lock, flags, ap->a_vlock, ap->a_td); 618 if (error) 619 VOP_UNLOCK(lvp, NULL, 0, ap->a_td); 620 return (error); 621 } 622 623 /* 624 * We need to process our own vnode unlock and then clear the 625 * interlock flag as it applies only to our vnode, not the 626 * vnodes below us on the stack. 627 * 628 * null_unlock(struct vnode *a_vp, lwkt_tokref_t a_vlock, int a_flags, 629 * struct thread *a_td) 630 */ 631 static int 632 null_unlock(struct vop_unlock_args *ap) 633 { 634 struct vnode *vp = ap->a_vp; 635 int flags = ap->a_flags; 636 struct null_node *np = VTONULL(vp); 637 struct vnode *lvp; 638 639 if (vp->v_vnlock != NULL) { 640 if (flags & LK_THISLAYER) 641 return 0; /* the lock is shared across layers */ 642 flags &= ~LK_THISLAYER; 643 return (lockmgr(vp->v_vnlock, flags | LK_RELEASE, 644 ap->a_vlock, ap->a_td)); 645 } 646 lvp = NULLVPTOLOWERVP(vp); 647 if (lvp == NULL) 648 return (lockmgr(&np->null_lock, flags | LK_RELEASE, ap->a_vlock, ap->a_td)); 649 if ((flags & LK_THISLAYER) == 0) { 650 if (flags & LK_INTERLOCK) { 651 VI_UNLOCK(ap->a_vlock, vp); 652 flags &= ~LK_INTERLOCK; 653 } 654 VOP_UNLOCK(lvp, ap->a_vlock, flags, ap->a_td); 655 } else { 656 flags &= ~LK_THISLAYER; 657 } 658 ap->a_flags = flags; 659 return (lockmgr(&np->null_lock, flags | LK_RELEASE, ap->a_vlock, ap->a_td)); 660 } 661 662 /* 663 * null_islocked(struct vnode *a_vp, struct thread *a_td) 664 */ 665 static int 666 null_islocked(struct vop_islocked_args *ap) 667 { 668 struct vnode *vp = ap->a_vp; 669 670 if (vp->v_vnlock != NULL) 671 return (lockstatus(vp->v_vnlock, ap->a_td)); 672 return (lockstatus(&VTONULL(vp)->null_lock, ap->a_td)); 673 } 674 675 676 /* 677 * There is no way to tell that someone issued remove/rmdir operation 678 * on the underlying filesystem. For now we just have to release lowevrp 679 * as soon as possible. 680 * 681 * null_inactive(struct vnode *a_vp, struct thread *a_td) 682 */ 683 static int 684 null_inactive(struct vop_inactive_args *ap) 685 { 686 struct vnode *vp = ap->a_vp; 687 struct null_node *xp = VTONULL(vp); 688 struct vnode *lowervp = xp->null_lowervp; 689 690 lockmgr(&null_hashlock, LK_EXCLUSIVE, NULL, ap->a_td); 691 LIST_REMOVE(xp, null_hash); 692 lockmgr(&null_hashlock, LK_RELEASE, NULL, ap->a_td); 693 694 xp->null_lowervp = NULLVP; 695 if (vp->v_vnlock != NULL) { 696 vp->v_vnlock = &xp->null_lock; /* we no longer share the lock */ 697 } else { 698 VOP_UNLOCK(vp, NULL, LK_THISLAYER, ap->a_td); 699 } 700 701 vput(lowervp); 702 /* 703 * Now it is safe to drop references to the lower vnode. 704 * VOP_INACTIVE() will be called by vrele() if necessary. 705 */ 706 vrele (lowervp); 707 708 return (0); 709 } 710 711 /* 712 * We can free memory in null_inactive, but we do this 713 * here. (Possible to guard vp->v_data to point somewhere) 714 * 715 * null_reclaim(struct vnode *a_vp, struct thread *a_td) 716 */ 717 static int 718 null_reclaim(struct vop_reclaim_args *ap) 719 { 720 struct vnode *vp = ap->a_vp; 721 void *vdata = vp->v_data; 722 723 vp->v_data = NULL; 724 FREE(vdata, M_NULLFSNODE); 725 726 return (0); 727 } 728 729 /* 730 * null_print(struct vnode *a_vp) 731 */ 732 static int 733 null_print(struct vop_print_args *ap) 734 { 735 struct vnode *vp = ap->a_vp; 736 737 printf ("\ttag VT_NULLFS, vp=%p, lowervp=%p\n", vp, NULLVPTOLOWERVP(vp)); 738 if (vp->v_vnlock != NULL) { 739 printf("\tvnlock: "); 740 lockmgr_printinfo(vp->v_vnlock); 741 } else { 742 printf("\tnull_lock: "); 743 lockmgr_printinfo(&VTONULL(vp)->null_lock); 744 } 745 printf("\n"); 746 return (0); 747 } 748 749 /* 750 * Let an underlying filesystem do the work 751 * 752 * null_createvobject(struct vnode *vp, struct ucred *cred, struct proc *p) 753 */ 754 static int 755 null_createvobject(struct vop_createvobject_args *ap) 756 { 757 struct vnode *vp = ap->a_vp; 758 struct vnode *lowervp = VTONULL(vp) ? NULLVPTOLOWERVP(vp) : NULL; 759 int error; 760 761 if (vp->v_type == VNON || lowervp == NULL) 762 return 0; 763 error = VOP_CREATEVOBJECT(lowervp, ap->a_td); 764 if (error) 765 return (error); 766 vp->v_flag |= VOBJBUF; 767 return (0); 768 } 769 770 /* 771 * We have nothing to destroy and this operation shouldn't be bypassed. 772 * 773 * null_destroyvobject(struct vnode *vp) 774 */ 775 static int 776 null_destroyvobject(struct vop_destroyvobject_args *ap) 777 { 778 struct vnode *vp = ap->a_vp; 779 780 vp->v_flag &= ~VOBJBUF; 781 return (0); 782 } 783 784 /* 785 * null_getvobject(struct vnode *vp, struct vm_object **objpp) 786 */ 787 static int 788 null_getvobject(struct vop_getvobject_args *ap) 789 { 790 struct vnode *lvp = NULLVPTOLOWERVP(ap->a_vp); 791 792 if (lvp == NULL) 793 return EINVAL; 794 return (VOP_GETVOBJECT(lvp, ap->a_objpp)); 795 } 796 797 /* 798 * Global vfs data structures 799 */ 800 vop_t **null_vnodeop_p; 801 static struct vnodeopv_entry_desc null_vnodeop_entries[] = { 802 { &vop_default_desc, (vop_t *) null_bypass }, 803 { &vop_access_desc, (vop_t *) null_access }, 804 { &vop_createvobject_desc, (vop_t *) null_createvobject }, 805 { &vop_destroyvobject_desc, (vop_t *) null_destroyvobject }, 806 { &vop_getattr_desc, (vop_t *) null_getattr }, 807 { &vop_getvobject_desc, (vop_t *) null_getvobject }, 808 { &vop_inactive_desc, (vop_t *) null_inactive }, 809 { &vop_islocked_desc, (vop_t *) null_islocked }, 810 { &vop_lock_desc, (vop_t *) null_lock }, 811 { &vop_lookup_desc, (vop_t *) null_lookup }, 812 { &vop_open_desc, (vop_t *) null_open }, 813 { &vop_print_desc, (vop_t *) null_print }, 814 { &vop_reclaim_desc, (vop_t *) null_reclaim }, 815 { &vop_rename_desc, (vop_t *) null_rename }, 816 { &vop_setattr_desc, (vop_t *) null_setattr }, 817 { &vop_unlock_desc, (vop_t *) null_unlock }, 818 { NULL, NULL } 819 }; 820 static struct vnodeopv_desc null_vnodeop_opv_desc = 821 { &null_vnodeop_p, null_vnodeop_entries }; 822 823 VNODEOP_SET(null_vnodeop_opv_desc); 824