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 * 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_vnops.c 8.6 (Berkeley) 5/27/95 33 * 34 * Ancestors: 35 * @(#)lofs_vnops.c 1.2 (Berkeley) 6/18/92 36 * ...and... 37 * @(#)null_vnodeops.c 1.20 92/07/07 UCLA Ficus project 38 *
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39 * $FreeBSD: head/sys/fs/nullfs/null_vnops.c 250505 2013-05-11 11:17:44Z kib $
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39 * $FreeBSD: head/sys/fs/nullfs/null_vnops.c 252714 2013-07-04 19:01:18Z kib $ |
40 */ 41 42/* 43 * Null Layer 44 * 45 * (See mount_nullfs(8) for more information.) 46 * 47 * The null layer duplicates a portion of the filesystem 48 * name space under a new name. In this respect, it is 49 * similar to the loopback filesystem. It differs from 50 * the loopback fs in two respects: it is implemented using 51 * a stackable layers techniques, and its "null-node"s stack above 52 * all lower-layer vnodes, not just over directory vnodes. 53 * 54 * The null layer has two purposes. First, it serves as a demonstration 55 * of layering by proving a layer which does nothing. (It actually 56 * does everything the loopback filesystem does, which is slightly 57 * more than nothing.) Second, the null layer can serve as a prototype 58 * layer. Since it provides all necessary layer framework, 59 * new filesystem layers can be created very easily be starting 60 * with a null layer. 61 * 62 * The remainder of this man page examines the null layer as a basis 63 * for constructing new layers. 64 * 65 * 66 * INSTANTIATING NEW NULL LAYERS 67 * 68 * New null layers are created with mount_nullfs(8). 69 * Mount_nullfs(8) takes two arguments, the pathname 70 * of the lower vfs (target-pn) and the pathname where the null 71 * layer will appear in the namespace (alias-pn). After 72 * the null layer is put into place, the contents 73 * of target-pn subtree will be aliased under alias-pn. 74 * 75 * 76 * OPERATION OF A NULL LAYER 77 * 78 * The null layer is the minimum filesystem layer, 79 * simply bypassing all possible operations to the lower layer 80 * for processing there. The majority of its activity centers 81 * on the bypass routine, through which nearly all vnode operations 82 * pass. 83 * 84 * The bypass routine accepts arbitrary vnode operations for 85 * handling by the lower layer. It begins by examing vnode 86 * operation arguments and replacing any null-nodes by their 87 * lower-layer equivlants. It then invokes the operation 88 * on the lower layer. Finally, it replaces the null-nodes 89 * in the arguments and, if a vnode is return by the operation, 90 * stacks a null-node on top of the returned vnode. 91 * 92 * Although bypass handles most operations, vop_getattr, vop_lock, 93 * vop_unlock, vop_inactive, vop_reclaim, and vop_print are not 94 * bypassed. Vop_getattr must change the fsid being returned. 95 * Vop_lock and vop_unlock must handle any locking for the 96 * current vnode as well as pass the lock request down. 97 * Vop_inactive and vop_reclaim are not bypassed so that 98 * they can handle freeing null-layer specific data. Vop_print 99 * is not bypassed to avoid excessive debugging information. 100 * Also, certain vnode operations change the locking state within 101 * the operation (create, mknod, remove, link, rename, mkdir, rmdir, 102 * and symlink). Ideally these operations should not change the 103 * lock state, but should be changed to let the caller of the 104 * function unlock them. Otherwise all intermediate vnode layers 105 * (such as union, umapfs, etc) must catch these functions to do 106 * the necessary locking at their layer. 107 * 108 * 109 * INSTANTIATING VNODE STACKS 110 * 111 * Mounting associates the null layer with a lower layer, 112 * effect stacking two VFSes. Vnode stacks are instead 113 * created on demand as files are accessed. 114 * 115 * The initial mount creates a single vnode stack for the 116 * root of the new null layer. All other vnode stacks 117 * are created as a result of vnode operations on 118 * this or other null vnode stacks. 119 * 120 * New vnode stacks come into existance as a result of 121 * an operation which returns a vnode. 122 * The bypass routine stacks a null-node above the new 123 * vnode before returning it to the caller. 124 * 125 * For example, imagine mounting a null layer with 126 * "mount_nullfs /usr/include /dev/layer/null". 127 * Changing directory to /dev/layer/null will assign 128 * the root null-node (which was created when the null layer was mounted). 129 * Now consider opening "sys". A vop_lookup would be 130 * done on the root null-node. This operation would bypass through 131 * to the lower layer which would return a vnode representing 132 * the UFS "sys". Null_bypass then builds a null-node 133 * aliasing the UFS "sys" and returns this to the caller. 134 * Later operations on the null-node "sys" will repeat this 135 * process when constructing other vnode stacks. 136 * 137 * 138 * CREATING OTHER FILE SYSTEM LAYERS 139 * 140 * One of the easiest ways to construct new filesystem layers is to make 141 * a copy of the null layer, rename all files and variables, and 142 * then begin modifing the copy. Sed can be used to easily rename 143 * all variables. 144 * 145 * The umap layer is an example of a layer descended from the 146 * null layer. 147 * 148 * 149 * INVOKING OPERATIONS ON LOWER LAYERS 150 * 151 * There are two techniques to invoke operations on a lower layer 152 * when the operation cannot be completely bypassed. Each method 153 * is appropriate in different situations. In both cases, 154 * it is the responsibility of the aliasing layer to make 155 * the operation arguments "correct" for the lower layer 156 * by mapping a vnode arguments to the lower layer. 157 * 158 * The first approach is to call the aliasing layer's bypass routine. 159 * This method is most suitable when you wish to invoke the operation 160 * currently being handled on the lower layer. It has the advantage 161 * that the bypass routine already must do argument mapping. 162 * An example of this is null_getattrs in the null layer. 163 * 164 * A second approach is to directly invoke vnode operations on 165 * the lower layer with the VOP_OPERATIONNAME interface. 166 * The advantage of this method is that it is easy to invoke 167 * arbitrary operations on the lower layer. The disadvantage 168 * is that vnode arguments must be manualy mapped. 169 * 170 */ 171 172#include <sys/param.h> 173#include <sys/systm.h> 174#include <sys/conf.h> 175#include <sys/kernel.h> 176#include <sys/lock.h> 177#include <sys/malloc.h> 178#include <sys/mount.h> 179#include <sys/mutex.h> 180#include <sys/namei.h> 181#include <sys/sysctl.h> 182#include <sys/vnode.h> 183 184#include <fs/nullfs/null.h> 185 186#include <vm/vm.h> 187#include <vm/vm_extern.h> 188#include <vm/vm_object.h> 189#include <vm/vnode_pager.h> 190 191static int null_bug_bypass = 0; /* for debugging: enables bypass printf'ing */ 192SYSCTL_INT(_debug, OID_AUTO, nullfs_bug_bypass, CTLFLAG_RW, 193 &null_bug_bypass, 0, ""); 194 195/* 196 * This is the 10-Apr-92 bypass routine. 197 * This version has been optimized for speed, throwing away some 198 * safety checks. It should still always work, but it's not as 199 * robust to programmer errors. 200 * 201 * In general, we map all vnodes going down and unmap them on the way back. 202 * As an exception to this, vnodes can be marked "unmapped" by setting 203 * the Nth bit in operation's vdesc_flags. 204 * 205 * Also, some BSD vnode operations have the side effect of vrele'ing 206 * their arguments. With stacking, the reference counts are held 207 * by the upper node, not the lower one, so we must handle these 208 * side-effects here. This is not of concern in Sun-derived systems 209 * since there are no such side-effects. 210 * 211 * This makes the following assumptions: 212 * - only one returned vpp 213 * - no INOUT vpp's (Sun's vop_open has one of these) 214 * - the vnode operation vector of the first vnode should be used 215 * to determine what implementation of the op should be invoked 216 * - all mapped vnodes are of our vnode-type (NEEDSWORK: 217 * problems on rmdir'ing mount points and renaming?) 218 */ 219int 220null_bypass(struct vop_generic_args *ap) 221{ 222 struct vnode **this_vp_p; 223 int error; 224 struct vnode *old_vps[VDESC_MAX_VPS]; 225 struct vnode **vps_p[VDESC_MAX_VPS]; 226 struct vnode ***vppp; 227 struct vnodeop_desc *descp = ap->a_desc; 228 int reles, i; 229 230 if (null_bug_bypass) 231 printf ("null_bypass: %s\n", descp->vdesc_name); 232 233#ifdef DIAGNOSTIC 234 /* 235 * We require at least one vp. 236 */ 237 if (descp->vdesc_vp_offsets == NULL || 238 descp->vdesc_vp_offsets[0] == VDESC_NO_OFFSET) 239 panic ("null_bypass: no vp's in map"); 240#endif 241 242 /* 243 * Map the vnodes going in. 244 * Later, we'll invoke the operation based on 245 * the first mapped vnode's operation vector. 246 */ 247 reles = descp->vdesc_flags; 248 for (i = 0; i < VDESC_MAX_VPS; reles >>= 1, i++) { 249 if (descp->vdesc_vp_offsets[i] == VDESC_NO_OFFSET) 250 break; /* bail out at end of list */ 251 vps_p[i] = this_vp_p = 252 VOPARG_OFFSETTO(struct vnode**,descp->vdesc_vp_offsets[i],ap); 253 /* 254 * We're not guaranteed that any but the first vnode 255 * are of our type. Check for and don't map any 256 * that aren't. (We must always map first vp or vclean fails.) 257 */ 258 if (i && (*this_vp_p == NULLVP || 259 (*this_vp_p)->v_op != &null_vnodeops)) { 260 old_vps[i] = NULLVP; 261 } else { 262 old_vps[i] = *this_vp_p; 263 *(vps_p[i]) = NULLVPTOLOWERVP(*this_vp_p); 264 /* 265 * XXX - Several operations have the side effect 266 * of vrele'ing their vp's. We must account for 267 * that. (This should go away in the future.) 268 */ 269 if (reles & VDESC_VP0_WILLRELE) 270 VREF(*this_vp_p); 271 } 272 273 } 274 275 /* 276 * Call the operation on the lower layer 277 * with the modified argument structure. 278 */ 279 if (vps_p[0] && *vps_p[0]) 280 error = VCALL(ap); 281 else { 282 printf("null_bypass: no map for %s\n", descp->vdesc_name); 283 error = EINVAL; 284 } 285 286 /* 287 * Maintain the illusion of call-by-value 288 * by restoring vnodes in the argument structure 289 * to their original value. 290 */ 291 reles = descp->vdesc_flags; 292 for (i = 0; i < VDESC_MAX_VPS; reles >>= 1, i++) { 293 if (descp->vdesc_vp_offsets[i] == VDESC_NO_OFFSET) 294 break; /* bail out at end of list */ 295 if (old_vps[i]) { 296 *(vps_p[i]) = old_vps[i]; 297#if 0 298 if (reles & VDESC_VP0_WILLUNLOCK) 299 VOP_UNLOCK(*(vps_p[i]), 0); 300#endif 301 if (reles & VDESC_VP0_WILLRELE) 302 vrele(*(vps_p[i])); 303 } 304 } 305 306 /* 307 * Map the possible out-going vpp 308 * (Assumes that the lower layer always returns 309 * a VREF'ed vpp unless it gets an error.) 310 */ 311 if (descp->vdesc_vpp_offset != VDESC_NO_OFFSET && 312 !(descp->vdesc_flags & VDESC_NOMAP_VPP) && 313 !error) { 314 /* 315 * XXX - even though some ops have vpp returned vp's, 316 * several ops actually vrele this before returning. 317 * We must avoid these ops. 318 * (This should go away when these ops are regularized.) 319 */ 320 if (descp->vdesc_flags & VDESC_VPP_WILLRELE) 321 goto out; 322 vppp = VOPARG_OFFSETTO(struct vnode***, 323 descp->vdesc_vpp_offset,ap); 324 if (*vppp) 325 error = null_nodeget(old_vps[0]->v_mount, **vppp, *vppp); 326 } 327 328 out: 329 return (error); 330} 331 332static int 333null_add_writecount(struct vop_add_writecount_args *ap) 334{ 335 struct vnode *lvp, *vp; 336 int error; 337 338 vp = ap->a_vp; 339 lvp = NULLVPTOLOWERVP(vp); 340 KASSERT(vp->v_writecount + ap->a_inc >= 0, ("wrong writecount inc")); 341 if (vp->v_writecount > 0 && vp->v_writecount + ap->a_inc == 0) 342 error = VOP_ADD_WRITECOUNT(lvp, -1); 343 else if (vp->v_writecount == 0 && vp->v_writecount + ap->a_inc > 0) 344 error = VOP_ADD_WRITECOUNT(lvp, 1); 345 else 346 error = 0; 347 if (error == 0) 348 vp->v_writecount += ap->a_inc; 349 return (error); 350} 351 352/* 353 * We have to carry on the locking protocol on the null layer vnodes 354 * as we progress through the tree. We also have to enforce read-only 355 * if this layer is mounted read-only. 356 */ 357static int 358null_lookup(struct vop_lookup_args *ap) 359{ 360 struct componentname *cnp = ap->a_cnp; 361 struct vnode *dvp = ap->a_dvp; 362 int flags = cnp->cn_flags; 363 struct vnode *vp, *ldvp, *lvp; 364 int error; 365 366 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 367 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 368 return (EROFS); 369 /* 370 * Although it is possible to call null_bypass(), we'll do 371 * a direct call to reduce overhead 372 */ 373 ldvp = NULLVPTOLOWERVP(dvp); 374 vp = lvp = NULL; 375 error = VOP_LOOKUP(ldvp, &lvp, cnp); 376 if (error == EJUSTRETURN && (flags & ISLASTCN) && 377 (dvp->v_mount->mnt_flag & MNT_RDONLY) && 378 (cnp->cn_nameiop == CREATE || cnp->cn_nameiop == RENAME)) 379 error = EROFS; 380 381 if ((error == 0 || error == EJUSTRETURN) && lvp != NULL) { 382 if (ldvp == lvp) { 383 *ap->a_vpp = dvp; 384 VREF(dvp); 385 vrele(lvp); 386 } else { 387 error = null_nodeget(dvp->v_mount, lvp, &vp); 388 if (error == 0) 389 *ap->a_vpp = vp; 390 } 391 } 392 return (error); 393} 394 395static int 396null_open(struct vop_open_args *ap) 397{ 398 int retval; 399 struct vnode *vp, *ldvp; 400 401 vp = ap->a_vp; 402 ldvp = NULLVPTOLOWERVP(vp); 403 retval = null_bypass(&ap->a_gen); 404 if (retval == 0) 405 vp->v_object = ldvp->v_object; 406 return (retval); 407} 408 409/* 410 * Setattr call. Disallow write attempts if the layer is mounted read-only. 411 */ 412static int 413null_setattr(struct vop_setattr_args *ap) 414{ 415 struct vnode *vp = ap->a_vp; 416 struct vattr *vap = ap->a_vap; 417 418 if ((vap->va_flags != VNOVAL || vap->va_uid != (uid_t)VNOVAL || 419 vap->va_gid != (gid_t)VNOVAL || vap->va_atime.tv_sec != VNOVAL || 420 vap->va_mtime.tv_sec != VNOVAL || vap->va_mode != (mode_t)VNOVAL) && 421 (vp->v_mount->mnt_flag & MNT_RDONLY)) 422 return (EROFS); 423 if (vap->va_size != VNOVAL) { 424 switch (vp->v_type) { 425 case VDIR: 426 return (EISDIR); 427 case VCHR: 428 case VBLK: 429 case VSOCK: 430 case VFIFO: 431 if (vap->va_flags != VNOVAL) 432 return (EOPNOTSUPP); 433 return (0); 434 case VREG: 435 case VLNK: 436 default: 437 /* 438 * Disallow write attempts if the filesystem is 439 * mounted read-only. 440 */ 441 if (vp->v_mount->mnt_flag & MNT_RDONLY) 442 return (EROFS); 443 } 444 } 445 446 return (null_bypass((struct vop_generic_args *)ap)); 447} 448 449/* 450 * We handle getattr only to change the fsid. 451 */ 452static int 453null_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 */ 467static int 468null_access(struct vop_access_args *ap) 469{ 470 struct vnode *vp = ap->a_vp; 471 accmode_t accmode = ap->a_accmode; 472 473 /* 474 * Disallow write attempts on read-only layers; 475 * unless the file is a socket, fifo, or a block or 476 * character device resident on the filesystem. 477 */ 478 if (accmode & VWRITE) { 479 switch (vp->v_type) { 480 case VDIR: 481 case VLNK: 482 case VREG: 483 if (vp->v_mount->mnt_flag & MNT_RDONLY) 484 return (EROFS); 485 break; 486 default: 487 break; 488 } 489 } 490 return (null_bypass((struct vop_generic_args *)ap)); 491} 492 493static int 494null_accessx(struct vop_accessx_args *ap) 495{ 496 struct vnode *vp = ap->a_vp; 497 accmode_t accmode = ap->a_accmode; 498 499 /* 500 * Disallow write attempts on read-only layers; 501 * unless the file is a socket, fifo, or a block or 502 * character device resident on the filesystem. 503 */ 504 if (accmode & VWRITE) { 505 switch (vp->v_type) { 506 case VDIR: 507 case VLNK: 508 case VREG: 509 if (vp->v_mount->mnt_flag & MNT_RDONLY) 510 return (EROFS); 511 break; 512 default: 513 break; 514 } 515 } 516 return (null_bypass((struct vop_generic_args *)ap)); 517} 518 519/* 520 * Increasing refcount of lower vnode is needed at least for the case 521 * when lower FS is NFS to do sillyrename if the file is in use. 522 * Unfortunately v_usecount is incremented in many places in 523 * the kernel and, as such, there may be races that result in 524 * the NFS client doing an extraneous silly rename, but that seems 525 * preferable to not doing a silly rename when it is needed. 526 */ 527static int 528null_remove(struct vop_remove_args *ap) 529{ 530 int retval, vreleit; 531 struct vnode *lvp; 532 533 if (vrefcnt(ap->a_vp) > 1) { 534 lvp = NULLVPTOLOWERVP(ap->a_vp); 535 VREF(lvp); 536 vreleit = 1; 537 } else 538 vreleit = 0; 539 retval = null_bypass(&ap->a_gen); 540 if (vreleit != 0) 541 vrele(lvp); 542 return (retval); 543} 544 545/* 546 * We handle this to eliminate null FS to lower FS 547 * file moving. Don't know why we don't allow this, 548 * possibly we should. 549 */ 550static int 551null_rename(struct vop_rename_args *ap) 552{ 553 struct vnode *tdvp = ap->a_tdvp; 554 struct vnode *fvp = ap->a_fvp; 555 struct vnode *fdvp = ap->a_fdvp; 556 struct vnode *tvp = ap->a_tvp;
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557 struct null_node *tnn; |
558 559 /* Check for cross-device rename. */ 560 if ((fvp->v_mount != tdvp->v_mount) || 561 (tvp && (fvp->v_mount != tvp->v_mount))) { 562 if (tdvp == tvp) 563 vrele(tdvp); 564 else 565 vput(tdvp); 566 if (tvp) 567 vput(tvp); 568 vrele(fdvp); 569 vrele(fvp); 570 return (EXDEV); 571 }
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571
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572 573 if (tvp != NULL) { 574 tnn = VTONULL(tvp); 575 tnn->null_flags |= NULLV_DROP; 576 } |
577 return (null_bypass((struct vop_generic_args *)ap)); 578} 579 580/* 581 * We need to process our own vnode lock and then clear the 582 * interlock flag as it applies only to our vnode, not the 583 * vnodes below us on the stack. 584 */ 585static int 586null_lock(struct vop_lock1_args *ap) 587{ 588 struct vnode *vp = ap->a_vp; 589 int flags = ap->a_flags; 590 struct null_node *nn; 591 struct vnode *lvp; 592 int error; 593 594 595 if ((flags & LK_INTERLOCK) == 0) { 596 VI_LOCK(vp); 597 ap->a_flags = flags |= LK_INTERLOCK; 598 } 599 nn = VTONULL(vp); 600 /* 601 * If we're still active we must ask the lower layer to 602 * lock as ffs has special lock considerations in it's 603 * vop lock. 604 */ 605 if (nn != NULL && (lvp = NULLVPTOLOWERVP(vp)) != NULL) { 606 VI_LOCK_FLAGS(lvp, MTX_DUPOK); 607 VI_UNLOCK(vp); 608 /* 609 * We have to hold the vnode here to solve a potential 610 * reclaim race. If we're forcibly vgone'd while we 611 * still have refs, a thread could be sleeping inside 612 * the lowervp's vop_lock routine. When we vgone we will 613 * drop our last ref to the lowervp, which would allow it 614 * to be reclaimed. The lowervp could then be recycled, 615 * in which case it is not legal to be sleeping in it's VOP. 616 * We prevent it from being recycled by holding the vnode 617 * here. 618 */ 619 vholdl(lvp); 620 error = VOP_LOCK(lvp, flags); 621 622 /* 623 * We might have slept to get the lock and someone might have 624 * clean our vnode already, switching vnode lock from one in 625 * lowervp to v_lock in our own vnode structure. Handle this 626 * case by reacquiring correct lock in requested mode. 627 */ 628 if (VTONULL(vp) == NULL && error == 0) { 629 ap->a_flags &= ~(LK_TYPE_MASK | LK_INTERLOCK); 630 switch (flags & LK_TYPE_MASK) { 631 case LK_SHARED: 632 ap->a_flags |= LK_SHARED; 633 break; 634 case LK_UPGRADE: 635 case LK_EXCLUSIVE: 636 ap->a_flags |= LK_EXCLUSIVE; 637 break; 638 default: 639 panic("Unsupported lock request %d\n", 640 ap->a_flags); 641 } 642 VOP_UNLOCK(lvp, 0); 643 error = vop_stdlock(ap); 644 } 645 vdrop(lvp); 646 } else 647 error = vop_stdlock(ap); 648 649 return (error); 650} 651 652/* 653 * We need to process our own vnode unlock and then clear the 654 * interlock flag as it applies only to our vnode, not the 655 * vnodes below us on the stack. 656 */ 657static int 658null_unlock(struct vop_unlock_args *ap) 659{ 660 struct vnode *vp = ap->a_vp; 661 int flags = ap->a_flags; 662 int mtxlkflag = 0; 663 struct null_node *nn; 664 struct vnode *lvp; 665 int error; 666 667 if ((flags & LK_INTERLOCK) != 0) 668 mtxlkflag = 1; 669 else if (mtx_owned(VI_MTX(vp)) == 0) { 670 VI_LOCK(vp); 671 mtxlkflag = 2; 672 } 673 nn = VTONULL(vp); 674 if (nn != NULL && (lvp = NULLVPTOLOWERVP(vp)) != NULL) { 675 VI_LOCK_FLAGS(lvp, MTX_DUPOK); 676 flags |= LK_INTERLOCK; 677 vholdl(lvp); 678 VI_UNLOCK(vp); 679 error = VOP_UNLOCK(lvp, flags); 680 vdrop(lvp); 681 if (mtxlkflag == 0) 682 VI_LOCK(vp); 683 } else { 684 if (mtxlkflag == 2) 685 VI_UNLOCK(vp); 686 error = vop_stdunlock(ap); 687 } 688 689 return (error); 690} 691 692/* 693 * Do not allow the VOP_INACTIVE to be passed to the lower layer, 694 * since the reference count on the lower vnode is not related to 695 * ours. 696 */ 697static int 698null_inactive(struct vop_inactive_args *ap __unused) 699{ 700 struct vnode *vp, *lvp; 701 struct null_node *xp; 702 struct mount *mp; 703 struct null_mount *xmp; 704 705 vp = ap->a_vp; 706 xp = VTONULL(vp); 707 lvp = NULLVPTOLOWERVP(vp); 708 mp = vp->v_mount; 709 xmp = MOUNTTONULLMOUNT(mp); 710 if ((xmp->nullm_flags & NULLM_CACHE) == 0 || 711 (xp->null_flags & NULLV_DROP) != 0 || 712 (lvp->v_vflag & VV_NOSYNC) != 0) { 713 /* 714 * If this is the last reference and caching of the 715 * nullfs vnodes is not enabled, or the lower vnode is 716 * deleted, then free up the vnode so as not to tie up 717 * the lower vnodes. 718 */ 719 vp->v_object = NULL; 720 vrecycle(vp); 721 } 722 return (0); 723} 724 725/* 726 * Now, the nullfs vnode and, due to the sharing lock, the lower 727 * vnode, are exclusively locked, and we shall destroy the null vnode. 728 */ 729static int 730null_reclaim(struct vop_reclaim_args *ap) 731{ 732 struct vnode *vp; 733 struct null_node *xp; 734 struct vnode *lowervp; 735 736 vp = ap->a_vp; 737 xp = VTONULL(vp); 738 lowervp = xp->null_lowervp; 739 740 KASSERT(lowervp != NULL && vp->v_vnlock != &vp->v_lock, 741 ("Reclaiming inclomplete null vnode %p", vp)); 742 743 null_hashrem(xp); 744 /* 745 * Use the interlock to protect the clearing of v_data to 746 * prevent faults in null_lock(). 747 */ 748 lockmgr(&vp->v_lock, LK_EXCLUSIVE, NULL); 749 VI_LOCK(vp); 750 vp->v_data = NULL; 751 vp->v_object = NULL; 752 vp->v_vnlock = &vp->v_lock; 753 VI_UNLOCK(vp); 754 755 /* 756 * If we were opened for write, we leased one write reference 757 * to the lower vnode. If this is a reclamation due to the 758 * forced unmount, undo the reference now. 759 */ 760 if (vp->v_writecount > 0) 761 VOP_ADD_WRITECOUNT(lowervp, -1); 762 if ((xp->null_flags & NULLV_NOUNLOCK) != 0) 763 vunref(lowervp); 764 else 765 vput(lowervp); 766 free(xp, M_NULLFSNODE); 767 768 return (0); 769} 770 771static int 772null_print(struct vop_print_args *ap) 773{ 774 struct vnode *vp = ap->a_vp; 775 776 printf("\tvp=%p, lowervp=%p\n", vp, VTONULL(vp)->null_lowervp); 777 return (0); 778} 779 780/* ARGSUSED */ 781static int 782null_getwritemount(struct vop_getwritemount_args *ap) 783{ 784 struct null_node *xp; 785 struct vnode *lowervp; 786 struct vnode *vp; 787 788 vp = ap->a_vp; 789 VI_LOCK(vp); 790 xp = VTONULL(vp); 791 if (xp && (lowervp = xp->null_lowervp)) { 792 VI_LOCK_FLAGS(lowervp, MTX_DUPOK); 793 VI_UNLOCK(vp); 794 vholdl(lowervp); 795 VI_UNLOCK(lowervp); 796 VOP_GETWRITEMOUNT(lowervp, ap->a_mpp); 797 vdrop(lowervp); 798 } else { 799 VI_UNLOCK(vp); 800 *(ap->a_mpp) = NULL; 801 } 802 return (0); 803} 804 805static int 806null_vptofh(struct vop_vptofh_args *ap) 807{ 808 struct vnode *lvp; 809 810 lvp = NULLVPTOLOWERVP(ap->a_vp); 811 return VOP_VPTOFH(lvp, ap->a_fhp); 812} 813 814static int 815null_vptocnp(struct vop_vptocnp_args *ap) 816{ 817 struct vnode *vp = ap->a_vp; 818 struct vnode **dvp = ap->a_vpp; 819 struct vnode *lvp, *ldvp; 820 struct ucred *cred = ap->a_cred; 821 int error, locked; 822 823 if (vp->v_type == VDIR) 824 return (vop_stdvptocnp(ap)); 825 826 locked = VOP_ISLOCKED(vp); 827 lvp = NULLVPTOLOWERVP(vp); 828 vhold(lvp); 829 VOP_UNLOCK(vp, 0); /* vp is held by vn_vptocnp_locked that called us */ 830 ldvp = lvp; 831 vref(lvp); 832 error = vn_vptocnp(&ldvp, cred, ap->a_buf, ap->a_buflen); 833 vdrop(lvp); 834 if (error != 0) { 835 vn_lock(vp, locked | LK_RETRY); 836 return (ENOENT); 837 } 838 839 /* 840 * Exclusive lock is required by insmntque1 call in 841 * null_nodeget() 842 */ 843 error = vn_lock(ldvp, LK_EXCLUSIVE); 844 if (error != 0) { 845 vrele(ldvp); 846 vn_lock(vp, locked | LK_RETRY); 847 return (ENOENT); 848 } 849 vref(ldvp); 850 error = null_nodeget(vp->v_mount, ldvp, dvp); 851 if (error == 0) { 852#ifdef DIAGNOSTIC 853 NULLVPTOLOWERVP(*dvp); 854#endif 855 VOP_UNLOCK(*dvp, 0); /* keep reference on *dvp */ 856 } 857 vn_lock(vp, locked | LK_RETRY); 858 return (error); 859} 860 861/* 862 * Global vfs data structures 863 */ 864struct vop_vector null_vnodeops = { 865 .vop_bypass = null_bypass, 866 .vop_access = null_access, 867 .vop_accessx = null_accessx, 868 .vop_advlockpurge = vop_stdadvlockpurge, 869 .vop_bmap = VOP_EOPNOTSUPP, 870 .vop_getattr = null_getattr, 871 .vop_getwritemount = null_getwritemount, 872 .vop_inactive = null_inactive, 873 .vop_islocked = vop_stdislocked, 874 .vop_lock1 = null_lock, 875 .vop_lookup = null_lookup, 876 .vop_open = null_open, 877 .vop_print = null_print, 878 .vop_reclaim = null_reclaim, 879 .vop_remove = null_remove, 880 .vop_rename = null_rename, 881 .vop_setattr = null_setattr, 882 .vop_strategy = VOP_EOPNOTSUPP, 883 .vop_unlock = null_unlock, 884 .vop_vptocnp = null_vptocnp, 885 .vop_vptofh = null_vptofh, 886 .vop_add_writecount = null_add_writecount, 887};
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