1 /* $NetBSD: layer_vnops.c,v 1.7 2001/07/24 15:39:32 assar Exp $ */ 2 3 /* 4 * Copyright (c) 1999 National Aeronautics & Space Administration 5 * All rights reserved. 6 * 7 * This software was written by William Studenmund of the 8 * Numerical Aerospace Simulation Facility, NASA Ames Research Center. 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 National Aeronautics & Space Administration 19 * nor the names of its contributors may be used to endorse or promote 20 * products derived from this software without specific prior written 21 * permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE NATIONAL AERONAUTICS & SPACE ADMINISTRATION 24 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 25 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 26 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE ADMINISTRATION OR CONTRIB- 27 * UTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, 28 * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 29 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 30 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 31 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 32 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 33 * POSSIBILITY OF SUCH DAMAGE. 34 */ 35 /* 36 * Copyright (c) 1992, 1993 37 * The Regents of the University of California. All rights reserved. 38 * 39 * This code is derived from software contributed to Berkeley by 40 * John Heidemann of the UCLA Ficus project. 41 * 42 * Redistribution and use in source and binary forms, with or without 43 * modification, are permitted provided that the following conditions 44 * are met: 45 * 1. Redistributions of source code must retain the above copyright 46 * notice, this list of conditions and the following disclaimer. 47 * 2. Redistributions in binary form must reproduce the above copyright 48 * notice, this list of conditions and the following disclaimer in the 49 * documentation and/or other materials provided with the distribution. 50 * 3. All advertising materials mentioning features or use of this software 51 * must display the following acknowledgement: 52 * This product includes software developed by the University of 53 * California, Berkeley and its contributors. 54 * 4. Neither the name of the University nor the names of its contributors 55 * may be used to endorse or promote products derived from this software 56 * without specific prior written permission. 57 * 58 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 59 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 60 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 61 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 62 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 63 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 64 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 65 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 66 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 67 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 68 * SUCH DAMAGE. 69 * 70 * @(#)null_vnops.c 8.6 (Berkeley) 5/27/95 71 * 72 * Ancestors: 73 * @(#)lofs_vnops.c 1.2 (Berkeley) 6/18/92 74 * $Id: layer_vnops.c,v 1.7 2001/07/24 15:39:32 assar Exp $ 75 * ...and... 76 * @(#)null_vnodeops.c 1.20 92/07/07 UCLA Ficus project 77 */ 78 79 /* 80 * Null Layer vnode routines. 81 * 82 * (See mount_null(8) for more information.) 83 * 84 * The layer.h, layer_extern.h, layer_vfs.c, and layer_vnops.c files provide 85 * the core implimentation of the null file system and most other stacked 86 * fs's. The description below refers to the null file system, but the 87 * services provided by the layer* files are useful for all layered fs's. 88 * 89 * The null layer duplicates a portion of the file system 90 * name space under a new name. In this respect, it is 91 * similar to the loopback file system. It differs from 92 * the loopback fs in two respects: it is implemented using 93 * a stackable layers techniques, and it's "null-node"s stack above 94 * all lower-layer vnodes, not just over directory vnodes. 95 * 96 * The null layer has two purposes. First, it serves as a demonstration 97 * of layering by proving a layer which does nothing. (It actually 98 * does everything the loopback file system does, which is slightly 99 * more than nothing.) Second, the null layer can serve as a prototype 100 * layer. Since it provides all necessary layer framework, 101 * new file system layers can be created very easily be starting 102 * with a null layer. 103 * 104 * The remainder of the man page examines the null layer as a basis 105 * for constructing new layers. 106 * 107 * 108 * INSTANTIATING NEW NULL LAYERS 109 * 110 * New null layers are created with mount_null(8). 111 * Mount_null(8) takes two arguments, the pathname 112 * of the lower vfs (target-pn) and the pathname where the null 113 * layer will appear in the namespace (alias-pn). After 114 * the null layer is put into place, the contents 115 * of target-pn subtree will be aliased under alias-pn. 116 * 117 * It is conceivable that other overlay filesystems will take different 118 * parameters. For instance, data migration or access controll layers might 119 * only take one pathname which will serve both as the target-pn and 120 * alias-pn described above. 121 * 122 * 123 * OPERATION OF A NULL LAYER 124 * 125 * The null layer is the minimum file system layer, 126 * simply bypassing all possible operations to the lower layer 127 * for processing there. The majority of its activity centers 128 * on the bypass routine, though which nearly all vnode operations 129 * pass. 130 * 131 * The bypass routine accepts arbitrary vnode operations for 132 * handling by the lower layer. It begins by examing vnode 133 * operation arguments and replacing any layered nodes by their 134 * lower-layer equivlants. It then invokes the operation 135 * on the lower layer. Finally, it replaces the layered nodes 136 * in the arguments and, if a vnode is return by the operation, 137 * stacks a layered node on top of the returned vnode. 138 * 139 * The bypass routine in this file, layer_bypass(), is suitable for use 140 * by many different layered filesystems. It can be used by multiple 141 * filesystems simultaneously. Alternatively, a layered fs may provide 142 * its own bypass routine, in which case layer_bypass() should be used as 143 * a model. For instance, the main functionality provided by umapfs, the user 144 * identity mapping file system, is handled by a custom bypass routine. 145 * 146 * Typically a layered fs registers its selected bypass routine as the 147 * default vnode operation in its vnodeopv_entry_desc table. Additionally 148 * the filesystem must store the bypass entry point in the layerm_bypass 149 * field of struct layer_mount. All other layer routines in this file will 150 * use the layerm_bypass routine. 151 * 152 * Although the bypass routine handles most operations outright, a number 153 * of operations are special cased, and handled by the layered fs. One 154 * group, layer_setattr, layer_getattr, layer_access, layer_open, and 155 * layer_fsync, perform layer-specific manipulation in addition to calling 156 * the bypass routine. The other group 157 158 * Although bypass handles most operations, vop_getattr, vop_lock, 159 * vop_unlock, vop_inactive, vop_reclaim, and vop_print are not 160 * bypassed. Vop_getattr must change the fsid being returned. 161 * Vop_lock and vop_unlock must handle any locking for the 162 * current vnode as well as pass the lock request down. 163 * Vop_inactive and vop_reclaim are not bypassed so that 164 * they can handle freeing null-layer specific data. Vop_print 165 * is not bypassed to avoid excessive debugging information. 166 * Also, certain vnode operations change the locking state within 167 * the operation (create, mknod, remove, link, rename, mkdir, rmdir, 168 * and symlink). Ideally these operations should not change the 169 * lock state, but should be changed to let the caller of the 170 * function unlock them. Otherwise all intermediate vnode layers 171 * (such as union, umapfs, etc) must catch these functions to do 172 * the necessary locking at their layer. 173 * 174 * 175 * INSTANTIATING VNODE STACKS 176 * 177 * Mounting associates the null layer with a lower layer, 178 * effect stacking two VFSes. Vnode stacks are instead 179 * created on demand as files are accessed. 180 * 181 * The initial mount creates a single vnode stack for the 182 * root of the new null layer. All other vnode stacks 183 * are created as a result of vnode operations on 184 * this or other null vnode stacks. 185 * 186 * New vnode stacks come into existance as a result of 187 * an operation which returns a vnode. 188 * The bypass routine stacks a null-node above the new 189 * vnode before returning it to the caller. 190 * 191 * For example, imagine mounting a null layer with 192 * "mount_null /usr/include /dev/layer/null". 193 * Changing directory to /dev/layer/null will assign 194 * the root null-node (which was created when the null layer was mounted). 195 * Now consider opening "sys". A vop_lookup would be 196 * done on the root null-node. This operation would bypass through 197 * to the lower layer which would return a vnode representing 198 * the UFS "sys". layer_bypass then builds a null-node 199 * aliasing the UFS "sys" and returns this to the caller. 200 * Later operations on the null-node "sys" will repeat this 201 * process when constructing other vnode stacks. 202 * 203 * 204 * CREATING OTHER FILE SYSTEM LAYERS 205 * 206 * One of the easiest ways to construct new file system layers is to make 207 * a copy of the null layer, rename all files and variables, and 208 * then begin modifing the copy. Sed can be used to easily rename 209 * all variables. 210 * 211 * The umap layer is an example of a layer descended from the 212 * null layer. 213 * 214 * 215 * INVOKING OPERATIONS ON LOWER LAYERS 216 * 217 * There are two techniques to invoke operations on a lower layer 218 * when the operation cannot be completely bypassed. Each method 219 * is appropriate in different situations. In both cases, 220 * it is the responsibility of the aliasing layer to make 221 * the operation arguments "correct" for the lower layer 222 * by mapping an vnode arguments to the lower layer. 223 * 224 * The first approach is to call the aliasing layer's bypass routine. 225 * This method is most suitable when you wish to invoke the operation 226 * currently being hanldled on the lower layer. It has the advantage 227 * that the bypass routine already must do argument mapping. 228 * An example of this is null_getattrs in the null layer. 229 * 230 * A second approach is to directly invoked vnode operations on 231 * the lower layer with the VOP_OPERATIONNAME interface. 232 * The advantage of this method is that it is easy to invoke 233 * arbitrary operations on the lower layer. The disadvantage 234 * is that vnodes arguments must be manualy mapped. 235 * 236 */ 237 238 #include <sys/param.h> 239 #include <sys/systm.h> 240 #include <sys/proc.h> 241 #include <sys/time.h> 242 #include <sys/types.h> 243 #include <sys/vnode.h> 244 #include <sys/mount.h> 245 #include <sys/namei.h> 246 #include <sys/malloc.h> 247 #include <sys/buf.h> 248 #include <miscfs/genfs/layer.h> 249 #include <miscfs/genfs/layer_extern.h> 250 #include <miscfs/genfs/genfs.h> 251 252 253 /* 254 * This is the 08-June-99 bypass routine, based on the 10-Apr-92 bypass 255 * routine by John Heidemann. 256 * The new element for this version is that the whole nullfs 257 * system gained the concept of locks on the lower node, and locks on 258 * our nodes. When returning from a call to the lower layer, we may 259 * need to update lock state ONLY on our layer. The LAYERFS_UPPER*LOCK() 260 * macros provide this functionality. 261 * The 10-Apr-92 version was optimized for speed, throwing away some 262 * safety checks. It should still always work, but it's not as 263 * robust to programmer errors. 264 * Define SAFETY to include some error checking code. 265 * 266 * In general, we map all vnodes going down and unmap them on the way back. 267 * 268 * Also, some BSD vnode operations have the side effect of vrele'ing 269 * their arguments. With stacking, the reference counts are held 270 * by the upper node, not the lower one, so we must handle these 271 * side-effects here. This is not of concern in Sun-derived systems 272 * since there are no such side-effects. 273 * 274 * New for the 08-June-99 version: we also handle operations which unlock 275 * the passed-in node (typically they vput the node). 276 * 277 * This makes the following assumptions: 278 * - only one returned vpp 279 * - no INOUT vpp's (Sun's vop_open has one of these) 280 * - the vnode operation vector of the first vnode should be used 281 * to determine what implementation of the op should be invoked 282 * - all mapped vnodes are of our vnode-type (NEEDSWORK: 283 * problems on rmdir'ing mount points and renaming?) 284 */ 285 int 286 layer_bypass(v) 287 void *v; 288 { 289 struct vop_generic_args /* { 290 struct vnodeop_desc *a_desc; 291 <other random data follows, presumably> 292 } */ *ap = v; 293 int (**our_vnodeop_p) __P((void *)); 294 struct vnode **this_vp_p; 295 int error, error1; 296 struct vnode *old_vps[VDESC_MAX_VPS], *vp0; 297 struct vnode **vps_p[VDESC_MAX_VPS]; 298 struct vnode ***vppp; 299 struct vnodeop_desc *descp = ap->a_desc; 300 int reles, i, flags; 301 302 #ifdef SAFETY 303 /* 304 * We require at least one vp. 305 */ 306 if (descp->vdesc_vp_offsets == NULL || 307 descp->vdesc_vp_offsets[0] == VDESC_NO_OFFSET) 308 panic ("layer_bypass: no vp's in map.\n"); 309 #endif 310 311 vps_p[0] = VOPARG_OFFSETTO(struct vnode**,descp->vdesc_vp_offsets[0],ap); 312 vp0 = *vps_p[0]; 313 flags = MOUNTTOLAYERMOUNT(vp0->v_mount)->layerm_flags; 314 our_vnodeop_p = vp0->v_op; 315 316 if (flags & LAYERFS_MBYPASSDEBUG) 317 printf ("layer_bypass: %s\n", descp->vdesc_name); 318 319 /* 320 * Map the vnodes going in. 321 * Later, we'll invoke the operation based on 322 * the first mapped vnode's operation vector. 323 */ 324 reles = descp->vdesc_flags; 325 for (i = 0; i < VDESC_MAX_VPS; reles >>= 1, i++) { 326 if (descp->vdesc_vp_offsets[i] == VDESC_NO_OFFSET) 327 break; /* bail out at end of list */ 328 vps_p[i] = this_vp_p = 329 VOPARG_OFFSETTO(struct vnode**,descp->vdesc_vp_offsets[i],ap); 330 /* 331 * We're not guaranteed that any but the first vnode 332 * are of our type. Check for and don't map any 333 * that aren't. (We must always map first vp or vclean fails.) 334 */ 335 if (i && (*this_vp_p == NULL || 336 (*this_vp_p)->v_op != our_vnodeop_p)) { 337 old_vps[i] = NULL; 338 } else { 339 old_vps[i] = *this_vp_p; 340 *(vps_p[i]) = LAYERVPTOLOWERVP(*this_vp_p); 341 /* 342 * XXX - Several operations have the side effect 343 * of vrele'ing their vp's. We must account for 344 * that. (This should go away in the future.) 345 */ 346 if (reles & VDESC_VP0_WILLRELE) 347 VREF(*this_vp_p); 348 } 349 350 } 351 352 /* 353 * Call the operation on the lower layer 354 * with the modified argument structure. 355 */ 356 error = VCALL(*vps_p[0], descp->vdesc_offset, ap); 357 358 /* 359 * Maintain the illusion of call-by-value 360 * by restoring vnodes in the argument structure 361 * to their original value. 362 */ 363 reles = descp->vdesc_flags; 364 for (i = 0; i < VDESC_MAX_VPS; reles >>= 1, i++) { 365 if (descp->vdesc_vp_offsets[i] == VDESC_NO_OFFSET) 366 break; /* bail out at end of list */ 367 if (old_vps[i]) { 368 *(vps_p[i]) = old_vps[i]; 369 if (reles & VDESC_VP0_WILLUNLOCK) 370 LAYERFS_UPPERUNLOCK(*(vps_p[i]), 0, error1); 371 if (reles & VDESC_VP0_WILLRELE) 372 vrele(*(vps_p[i])); 373 } 374 } 375 376 /* 377 * Map the possible out-going vpp 378 * (Assumes that the lower layer always returns 379 * a VREF'ed vpp unless it gets an error.) 380 */ 381 if (descp->vdesc_vpp_offset != VDESC_NO_OFFSET && 382 !(descp->vdesc_flags & VDESC_NOMAP_VPP) && 383 !error) { 384 /* 385 * XXX - even though some ops have vpp returned vp's, 386 * several ops actually vrele this before returning. 387 * We must avoid these ops. 388 * (This should go away when these ops are regularized.) 389 */ 390 if (descp->vdesc_flags & VDESC_VPP_WILLRELE) 391 goto out; 392 vppp = VOPARG_OFFSETTO(struct vnode***, 393 descp->vdesc_vpp_offset,ap); 394 /* 395 * Only vop_lookup, vop_create, vop_makedir, vop_bmap, 396 * vop_mknod, and vop_symlink return vpp's. vop_bmap 397 * doesn't call bypass as the lower vpp is fine (we're just 398 * going to do i/o on it). vop_loookup doesn't call bypass 399 * as a lookup on "." would generate a locking error. 400 * So all the calls which get us here have a locked vpp. :-) 401 */ 402 error = layer_node_create(old_vps[0]->v_mount, **vppp, *vppp); 403 } 404 405 out: 406 return (error); 407 } 408 409 /* 410 * We have to carry on the locking protocol on the layer vnodes 411 * as we progress through the tree. We also have to enforce read-only 412 * if this layer is mounted read-only. 413 */ 414 int 415 layer_lookup(v) 416 void *v; 417 { 418 struct vop_lookup_args /* { 419 struct vnodeop_desc *a_desc; 420 struct vnode * a_dvp; 421 struct vnode ** a_vpp; 422 struct componentname * a_cnp; 423 } */ *ap = v; 424 struct componentname *cnp = ap->a_cnp; 425 int flags = cnp->cn_flags; 426 struct vnode *dvp, *vp, *ldvp; 427 int error, r; 428 429 dvp = ap->a_dvp; 430 431 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && 432 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 433 return (EROFS); 434 435 ldvp = LAYERVPTOLOWERVP(dvp); 436 ap->a_dvp = ldvp; 437 error = VCALL(ldvp, ap->a_desc->vdesc_offset, ap); 438 vp = *ap->a_vpp; 439 440 if (error == EJUSTRETURN && (flags & ISLASTCN) && 441 (dvp->v_mount->mnt_flag & MNT_RDONLY) && 442 (cnp->cn_nameiop == CREATE || cnp->cn_nameiop == RENAME)) 443 error = EROFS; 444 /* 445 * We must do the same locking and unlocking at this layer as 446 * is done in the layers below us. It used to be we would try 447 * to guess based on what was set with the flags and error codes. 448 * 449 * But that doesn't work. So now we have the underlying VOP_LOOKUP 450 * tell us if it released the parent vnode, and we adjust the 451 * upper node accordingly. We can't just look at the lock states 452 * of the lower nodes as someone else might have come along and 453 * locked the parent node after our call to VOP_LOOKUP locked it. 454 */ 455 if ((cnp->cn_flags & PDIRUNLOCK)) { 456 LAYERFS_UPPERUNLOCK(dvp, 0, r); 457 } 458 if (ldvp == vp) { 459 /* 460 * Did lookup on "." or ".." in the root node of a mount point. 461 * So we return dvp after a VREF. 462 */ 463 *ap->a_vpp = dvp; 464 VREF(dvp); 465 vrele(vp); 466 } else if (vp != NULL) { 467 error = layer_node_create(dvp->v_mount, vp, ap->a_vpp); 468 } 469 return (error); 470 } 471 472 /* 473 * Setattr call. Disallow write attempts if the layer is mounted read-only. 474 */ 475 int 476 layer_setattr(v) 477 void *v; 478 { 479 struct vop_setattr_args /* { 480 struct vnodeop_desc *a_desc; 481 struct vnode *a_vp; 482 struct vattr *a_vap; 483 struct ucred *a_cred; 484 struct proc *a_p; 485 } */ *ap = v; 486 struct vnode *vp = ap->a_vp; 487 struct vattr *vap = ap->a_vap; 488 489 if ((vap->va_flags != VNOVAL || vap->va_uid != (uid_t)VNOVAL || 490 vap->va_gid != (gid_t)VNOVAL || vap->va_atime.tv_sec != VNOVAL || 491 vap->va_mtime.tv_sec != VNOVAL || vap->va_mode != (mode_t)VNOVAL) && 492 (vp->v_mount->mnt_flag & MNT_RDONLY)) 493 return (EROFS); 494 if (vap->va_size != VNOVAL) { 495 switch (vp->v_type) { 496 case VDIR: 497 return (EISDIR); 498 case VCHR: 499 case VBLK: 500 case VSOCK: 501 case VFIFO: 502 return (0); 503 case VREG: 504 case VLNK: 505 default: 506 /* 507 * Disallow write attempts if the filesystem is 508 * mounted read-only. 509 */ 510 if (vp->v_mount->mnt_flag & MNT_RDONLY) 511 return (EROFS); 512 } 513 } 514 return (LAYERFS_DO_BYPASS(vp, ap)); 515 } 516 517 /* 518 * We handle getattr only to change the fsid. 519 */ 520 int 521 layer_getattr(v) 522 void *v; 523 { 524 struct vop_getattr_args /* { 525 struct vnode *a_vp; 526 struct vattr *a_vap; 527 struct ucred *a_cred; 528 struct proc *a_p; 529 } */ *ap = v; 530 struct vnode *vp = ap->a_vp; 531 int error; 532 533 if ((error = LAYERFS_DO_BYPASS(vp, ap)) != 0) 534 return (error); 535 /* Requires that arguments be restored. */ 536 ap->a_vap->va_fsid = vp->v_mount->mnt_stat.f_fsid.val[0]; 537 return (0); 538 } 539 540 int 541 layer_access(v) 542 void *v; 543 { 544 struct vop_access_args /* { 545 struct vnode *a_vp; 546 int a_mode; 547 struct ucred *a_cred; 548 struct proc *a_p; 549 } */ *ap = v; 550 struct vnode *vp = ap->a_vp; 551 mode_t mode = ap->a_mode; 552 553 /* 554 * Disallow write attempts on read-only layers; 555 * unless the file is a socket, fifo, or a block or 556 * character device resident on the file system. 557 */ 558 if (mode & VWRITE) { 559 switch (vp->v_type) { 560 case VDIR: 561 case VLNK: 562 case VREG: 563 if (vp->v_mount->mnt_flag & MNT_RDONLY) 564 return (EROFS); 565 break; 566 default: 567 break; 568 } 569 } 570 return (LAYERFS_DO_BYPASS(vp, ap)); 571 } 572 573 /* 574 * We must handle open to be able to catch MNT_NODEV and friends. 575 */ 576 int 577 layer_open(v) 578 void *v; 579 { 580 struct vop_open_args *ap = v; 581 struct vnode *vp = ap->a_vp; 582 enum vtype lower_type = LAYERVPTOLOWERVP(vp)->v_type; 583 584 if (((lower_type == VBLK) || (lower_type == VCHR)) && 585 (vp->v_mount->mnt_flag & MNT_NODEV)) 586 return ENXIO; 587 588 return LAYERFS_DO_BYPASS(vp, ap); 589 } 590 591 /* 592 * We need to process our own vnode lock and then clear the 593 * interlock flag as it applies only to our vnode, not the 594 * vnodes below us on the stack. 595 */ 596 int 597 layer_lock(v) 598 void *v; 599 { 600 struct vop_lock_args /* { 601 struct vnode *a_vp; 602 int a_flags; 603 struct proc *a_p; 604 } */ *ap = v; 605 struct vnode *vp = ap->a_vp, *lowervp; 606 int flags = ap->a_flags, error; 607 608 if (vp->v_vnlock != NULL) { 609 /* 610 * The lower level has exported a struct lock to us. Use 611 * it so that all vnodes in the stack lock and unlock 612 * simultaneously. Note: we don't DRAIN the lock as DRAIN 613 * decommissions the lock - just because our vnode is 614 * going away doesn't mean the struct lock below us is. 615 * LK_EXCLUSIVE is fine. 616 */ 617 if ((flags & LK_TYPE_MASK) == LK_DRAIN) { 618 return(lockmgr(vp->v_vnlock, 619 (flags & ~LK_TYPE_MASK) | LK_EXCLUSIVE, 620 &vp->v_interlock)); 621 } else 622 return(lockmgr(vp->v_vnlock, flags, &vp->v_interlock)); 623 } else { 624 /* 625 * Ahh well. It would be nice if the fs we're over would 626 * export a struct lock for us to use, but it doesn't. 627 * 628 * To prevent race conditions involving doing a lookup 629 * on "..", we have to lock the lower node, then lock our 630 * node. Most of the time it won't matter that we lock our 631 * node (as any locking would need the lower one locked 632 * first). But we can LK_DRAIN the upper lock as a step 633 * towards decomissioning it. 634 */ 635 lowervp = LAYERVPTOLOWERVP(vp); 636 if (flags & LK_INTERLOCK) { 637 simple_unlock(&vp->v_interlock); 638 flags &= ~LK_INTERLOCK; 639 } 640 if ((flags & LK_TYPE_MASK) == LK_DRAIN) { 641 error = VOP_LOCK(lowervp, 642 (flags & ~LK_TYPE_MASK) | LK_EXCLUSIVE); 643 } else 644 error = VOP_LOCK(lowervp, flags); 645 if (error) 646 return (error); 647 if ((error = lockmgr(&vp->v_lock, flags, &vp->v_interlock))) { 648 VOP_UNLOCK(lowervp, 0); 649 } 650 return (error); 651 } 652 } 653 654 /* 655 */ 656 int 657 layer_unlock(v) 658 void *v; 659 { 660 struct vop_unlock_args /* { 661 struct vnode *a_vp; 662 int a_flags; 663 struct proc *a_p; 664 } */ *ap = v; 665 struct vnode *vp = ap->a_vp; 666 int flags = ap->a_flags; 667 668 if (vp->v_vnlock != NULL) { 669 return (lockmgr(vp->v_vnlock, ap->a_flags | LK_RELEASE, 670 &vp->v_interlock)); 671 } else { 672 if (flags & LK_INTERLOCK) { 673 simple_unlock(&vp->v_interlock); 674 flags &= ~LK_INTERLOCK; 675 } 676 VOP_UNLOCK(LAYERVPTOLOWERVP(vp), flags); 677 return (lockmgr(&vp->v_lock, ap->a_flags | LK_RELEASE, 678 &vp->v_interlock)); 679 } 680 } 681 682 /* 683 * As long as genfs_nolock is in use, don't call VOP_ISLOCKED(lowervp) 684 * if vp->v_vnlock == NULL as genfs_noislocked will always report 0. 685 */ 686 int 687 layer_islocked(v) 688 void *v; 689 { 690 struct vop_islocked_args /* { 691 struct vnode *a_vp; 692 } */ *ap = v; 693 struct vnode *vp = ap->a_vp; 694 695 if (vp->v_vnlock != NULL) 696 return (lockstatus(vp->v_vnlock)); 697 else 698 return (lockstatus(&vp->v_lock)); 699 } 700 701 /* 702 * If vinvalbuf is calling us, it's a "shallow fsync" -- don't bother 703 * syncing the underlying vnodes, since they'll be fsync'ed when 704 * reclaimed; otherwise, 705 * pass it through to the underlying layer. 706 * 707 * XXX Do we still need to worry about shallow fsync? 708 */ 709 710 int 711 layer_fsync(v) 712 void *v; 713 { 714 struct vop_fsync_args /* { 715 struct vnode *a_vp; 716 struct ucred *a_cred; 717 int a_flags; 718 off_t offlo; 719 off_t offhi; 720 struct proc *a_p; 721 } */ *ap = v; 722 723 if (ap->a_flags & FSYNC_RECLAIM) { 724 return 0; 725 } 726 727 return (LAYERFS_DO_BYPASS(ap->a_vp, ap)); 728 } 729 730 731 int 732 layer_inactive(v) 733 void *v; 734 { 735 struct vop_inactive_args /* { 736 struct vnode *a_vp; 737 struct proc *a_p; 738 } */ *ap = v; 739 struct vnode *vp = ap->a_vp; 740 741 /* 742 * Do nothing (and _don't_ bypass). 743 * Wait to vrele lowervp until reclaim, 744 * so that until then our layer_node is in the 745 * cache and reusable. 746 * 747 * NEEDSWORK: Someday, consider inactive'ing 748 * the lowervp and then trying to reactivate it 749 * with capabilities (v_id) 750 * like they do in the name lookup cache code. 751 * That's too much work for now. 752 */ 753 VOP_UNLOCK(vp, 0); 754 755 /* ..., but don't cache the device node. */ 756 if (vp->v_type == VBLK || vp->v_type == VCHR) 757 vgone(vp); 758 return (0); 759 } 760 761 int 762 layer_reclaim(v) 763 void *v; 764 { 765 struct vop_reclaim_args /* { 766 struct vnode *a_vp; 767 struct proc *a_p; 768 } */ *ap = v; 769 struct vnode *vp = ap->a_vp; 770 struct layer_mount *lmp = MOUNTTOLAYERMOUNT(vp->v_mount); 771 struct layer_node *xp = VTOLAYER(vp); 772 struct vnode *lowervp = xp->layer_lowervp; 773 774 /* 775 * Note: in vop_reclaim, the node's struct lock has been 776 * decomissioned, so we have to be careful about calling 777 * VOP's on ourself. Even if we turned a LK_DRAIN into an 778 * LK_EXCLUSIVE in layer_lock, we still must be careful as VXLOCK is 779 * set. 780 */ 781 /* After this assignment, this node will not be re-used. */ 782 if ((vp == lmp->layerm_rootvp)) { 783 /* 784 * Oops! We no longer have a root node. Most likely reason is 785 * that someone forcably unmunted the underlying fs. 786 * 787 * Now getting the root vnode will fail. We're dead. :-( 788 */ 789 lmp->layerm_rootvp = NULL; 790 } 791 xp->layer_lowervp = NULL; 792 simple_lock(&lmp->layerm_hashlock); 793 LIST_REMOVE(xp, layer_hash); 794 simple_unlock(&lmp->layerm_hashlock); 795 FREE(vp->v_data, M_TEMP); 796 vp->v_data = NULL; 797 vrele (lowervp); 798 return (0); 799 } 800 801 /* 802 * We just feed the returned vnode up to the caller - there's no need 803 * to build a layer node on top of the node on which we're going to do 804 * i/o. :-) 805 */ 806 int 807 layer_bmap(v) 808 void *v; 809 { 810 struct vop_bmap_args /* { 811 struct vnode *a_vp; 812 daddr_t a_bn; 813 struct vnode **a_vpp; 814 daddr_t *a_bnp; 815 int *a_runp; 816 } */ *ap = v; 817 struct vnode *vp; 818 819 ap->a_vp = vp = LAYERVPTOLOWERVP(ap->a_vp); 820 821 return (VCALL(vp, ap->a_desc->vdesc_offset, ap)); 822 } 823 824 int 825 layer_print(v) 826 void *v; 827 { 828 struct vop_print_args /* { 829 struct vnode *a_vp; 830 } */ *ap = v; 831 struct vnode *vp = ap->a_vp; 832 printf ("\ttag VT_LAYERFS, vp=%p, lowervp=%p\n", vp, LAYERVPTOLOWERVP(vp)); 833 return (0); 834 } 835 836 /* 837 * XXX - vop_strategy must be hand coded because it has no 838 * vnode in its arguments. 839 * This goes away with a merged VM/buffer cache. 840 */ 841 int 842 layer_strategy(v) 843 void *v; 844 { 845 struct vop_strategy_args /* { 846 struct buf *a_bp; 847 } */ *ap = v; 848 struct buf *bp = ap->a_bp; 849 int error; 850 struct vnode *savedvp; 851 852 savedvp = bp->b_vp; 853 bp->b_vp = LAYERVPTOLOWERVP(bp->b_vp); 854 855 error = VOP_STRATEGY(bp); 856 857 bp->b_vp = savedvp; 858 859 return (error); 860 } 861 862 /* 863 * XXX - like vop_strategy, vop_bwrite must be hand coded because it has no 864 * vnode in its arguments. 865 * This goes away with a merged VM/buffer cache. 866 */ 867 int 868 layer_bwrite(v) 869 void *v; 870 { 871 struct vop_bwrite_args /* { 872 struct buf *a_bp; 873 } */ *ap = v; 874 struct buf *bp = ap->a_bp; 875 int error; 876 struct vnode *savedvp; 877 878 savedvp = bp->b_vp; 879 bp->b_vp = LAYERVPTOLOWERVP(bp->b_vp); 880 881 error = VOP_BWRITE(bp); 882 883 bp->b_vp = savedvp; 884 885 return (error); 886 } 887