null_vnops.c revision 22607
11541Srgrimes/* 21541Srgrimes * Copyright (c) 1992, 1993 31541Srgrimes * The Regents of the University of California. All rights reserved. 41541Srgrimes * 51541Srgrimes * This code is derived from software contributed to Berkeley by 61541Srgrimes * John Heidemann of the UCLA Ficus project. 71541Srgrimes * 81541Srgrimes * Redistribution and use in source and binary forms, with or without 91541Srgrimes * modification, are permitted provided that the following conditions 101541Srgrimes * are met: 111541Srgrimes * 1. Redistributions of source code must retain the above copyright 121541Srgrimes * notice, this list of conditions and the following disclaimer. 131541Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 141541Srgrimes * notice, this list of conditions and the following disclaimer in the 151541Srgrimes * documentation and/or other materials provided with the distribution. 161541Srgrimes * 3. All advertising materials mentioning features or use of this software 171541Srgrimes * must display the following acknowledgement: 181541Srgrimes * This product includes software developed by the University of 191541Srgrimes * California, Berkeley and its contributors. 201541Srgrimes * 4. Neither the name of the University nor the names of its contributors 211541Srgrimes * may be used to endorse or promote products derived from this software 221541Srgrimes * without specific prior written permission. 231541Srgrimes * 241541Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 251541Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 261541Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 271541Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 281541Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 291541Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 301541Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 311541Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 321541Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 331541Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 341541Srgrimes * SUCH DAMAGE. 351541Srgrimes * 3622521Sdyson * @(#)null_vnops.c 8.6 (Berkeley) 5/27/95 371541Srgrimes * 3822521Sdyson * Ancestors: 3922521Sdyson * @(#)lofs_vnops.c 1.2 (Berkeley) 6/18/92 4022607Smpp * $Id: null_vnops.c,v 1.14 1997/02/12 14:55:01 mpp Exp $ 4122521Sdyson * ...and... 4222521Sdyson * @(#)null_vnodeops.c 1.20 92/07/07 UCLA Ficus project 4322521Sdyson * 4421673Sjkh * $FreeBSD: head/sys/fs/nullfs/null_vnops.c 22607 1997-02-12 18:06:08Z mpp $ 451541Srgrimes */ 461541Srgrimes 471541Srgrimes/* 481541Srgrimes * Null Layer 491541Srgrimes * 501541Srgrimes * (See mount_null(8) for more information.) 511541Srgrimes * 521541Srgrimes * The null layer duplicates a portion of the file system 531541Srgrimes * name space under a new name. In this respect, it is 541541Srgrimes * similar to the loopback file system. It differs from 551541Srgrimes * the loopback fs in two respects: it is implemented using 561541Srgrimes * a stackable layers techniques, and it's "null-node"s stack above 571541Srgrimes * all lower-layer vnodes, not just over directory vnodes. 581541Srgrimes * 591541Srgrimes * The null layer has two purposes. First, it serves as a demonstration 601541Srgrimes * of layering by proving a layer which does nothing. (It actually 611541Srgrimes * does everything the loopback file system does, which is slightly 621541Srgrimes * more than nothing.) Second, the null layer can serve as a prototype 631541Srgrimes * layer. Since it provides all necessary layer framework, 641541Srgrimes * new file system layers can be created very easily be starting 651541Srgrimes * with a null layer. 661541Srgrimes * 671541Srgrimes * The remainder of this man page examines the null layer as a basis 681541Srgrimes * for constructing new layers. 691541Srgrimes * 701541Srgrimes * 711541Srgrimes * INSTANTIATING NEW NULL LAYERS 721541Srgrimes * 731541Srgrimes * New null layers are created with mount_null(8). 741541Srgrimes * Mount_null(8) takes two arguments, the pathname 751541Srgrimes * of the lower vfs (target-pn) and the pathname where the null 761541Srgrimes * layer will appear in the namespace (alias-pn). After 771541Srgrimes * the null layer is put into place, the contents 781541Srgrimes * of target-pn subtree will be aliased under alias-pn. 791541Srgrimes * 801541Srgrimes * 811541Srgrimes * OPERATION OF A NULL LAYER 821541Srgrimes * 831541Srgrimes * The null layer is the minimum file system layer, 841541Srgrimes * simply bypassing all possible operations to the lower layer 851541Srgrimes * for processing there. The majority of its activity centers 861541Srgrimes * on the bypass routine, though which nearly all vnode operations 871541Srgrimes * pass. 881541Srgrimes * 891541Srgrimes * The bypass routine accepts arbitrary vnode operations for 901541Srgrimes * handling by the lower layer. It begins by examing vnode 911541Srgrimes * operation arguments and replacing any null-nodes by their 921541Srgrimes * lower-layer equivlants. It then invokes the operation 931541Srgrimes * on the lower layer. Finally, it replaces the null-nodes 941541Srgrimes * in the arguments and, if a vnode is return by the operation, 951541Srgrimes * stacks a null-node on top of the returned vnode. 961541Srgrimes * 9722521Sdyson * Although bypass handles most operations, vop_getattr, vop_lock, 9822521Sdyson * vop_unlock, vop_inactive, vop_reclaim, and vop_print are not 9922521Sdyson * bypassed. Vop_getattr must change the fsid being returned. 10022521Sdyson * Vop_lock and vop_unlock must handle any locking for the 10122521Sdyson * current vnode as well as pass the lock request down. 1021541Srgrimes * Vop_inactive and vop_reclaim are not bypassed so that 10322521Sdyson * they can handle freeing null-layer specific data. Vop_print 10422521Sdyson * is not bypassed to avoid excessive debugging information. 10522521Sdyson * Also, certain vnode operations change the locking state within 10622521Sdyson * the operation (create, mknod, remove, link, rename, mkdir, rmdir, 10722521Sdyson * and symlink). Ideally these operations should not change the 10822521Sdyson * lock state, but should be changed to let the caller of the 10922521Sdyson * function unlock them. Otherwise all intermediate vnode layers 11022521Sdyson * (such as union, umapfs, etc) must catch these functions to do 11122521Sdyson * the necessary locking at their layer. 1121541Srgrimes * 1131541Srgrimes * 1141541Srgrimes * INSTANTIATING VNODE STACKS 1151541Srgrimes * 1161541Srgrimes * Mounting associates the null layer with a lower layer, 1171541Srgrimes * effect stacking two VFSes. Vnode stacks are instead 1181541Srgrimes * created on demand as files are accessed. 1191541Srgrimes * 1201541Srgrimes * The initial mount creates a single vnode stack for the 1211541Srgrimes * root of the new null layer. All other vnode stacks 1221541Srgrimes * are created as a result of vnode operations on 1231541Srgrimes * this or other null vnode stacks. 1241541Srgrimes * 1251541Srgrimes * New vnode stacks come into existance as a result of 1268876Srgrimes * an operation which returns a vnode. 1271541Srgrimes * The bypass routine stacks a null-node above the new 1281541Srgrimes * vnode before returning it to the caller. 1291541Srgrimes * 1301541Srgrimes * For example, imagine mounting a null layer with 1311541Srgrimes * "mount_null /usr/include /dev/layer/null". 1321541Srgrimes * Changing directory to /dev/layer/null will assign 1331541Srgrimes * the root null-node (which was created when the null layer was mounted). 1341541Srgrimes * Now consider opening "sys". A vop_lookup would be 1351541Srgrimes * done on the root null-node. This operation would bypass through 1368876Srgrimes * to the lower layer which would return a vnode representing 1371541Srgrimes * the UFS "sys". Null_bypass then builds a null-node 1381541Srgrimes * aliasing the UFS "sys" and returns this to the caller. 1391541Srgrimes * Later operations on the null-node "sys" will repeat this 1401541Srgrimes * process when constructing other vnode stacks. 1411541Srgrimes * 1421541Srgrimes * 1431541Srgrimes * CREATING OTHER FILE SYSTEM LAYERS 1441541Srgrimes * 1451541Srgrimes * One of the easiest ways to construct new file system layers is to make 1461541Srgrimes * a copy of the null layer, rename all files and variables, and 1471541Srgrimes * then begin modifing the copy. Sed can be used to easily rename 1481541Srgrimes * all variables. 1491541Srgrimes * 1508876Srgrimes * The umap layer is an example of a layer descended from the 1511541Srgrimes * null layer. 1521541Srgrimes * 1531541Srgrimes * 1541541Srgrimes * INVOKING OPERATIONS ON LOWER LAYERS 1551541Srgrimes * 1568876Srgrimes * There are two techniques to invoke operations on a lower layer 1571541Srgrimes * when the operation cannot be completely bypassed. Each method 1581541Srgrimes * is appropriate in different situations. In both cases, 1591541Srgrimes * it is the responsibility of the aliasing layer to make 1601541Srgrimes * the operation arguments "correct" for the lower layer 1611541Srgrimes * by mapping an vnode arguments to the lower layer. 1621541Srgrimes * 1631541Srgrimes * The first approach is to call the aliasing layer's bypass routine. 1641541Srgrimes * This method is most suitable when you wish to invoke the operation 1651541Srgrimes * currently being hanldled on the lower layer. It has the advantage 1661541Srgrimes * that the bypass routine already must do argument mapping. 1671541Srgrimes * An example of this is null_getattrs in the null layer. 1681541Srgrimes * 1691541Srgrimes * A second approach is to directly invoked vnode operations on 1701541Srgrimes * the lower layer with the VOP_OPERATIONNAME interface. 1711541Srgrimes * The advantage of this method is that it is easy to invoke 1721541Srgrimes * arbitrary operations on the lower layer. The disadvantage 1731541Srgrimes * is that vnodes arguments must be manualy mapped. 1741541Srgrimes * 1751541Srgrimes */ 1761541Srgrimes 1771541Srgrimes#include <sys/param.h> 1781541Srgrimes#include <sys/systm.h> 1792960Swollman#include <sys/kernel.h> 18012769Sphk#include <sys/sysctl.h> 1811541Srgrimes#include <sys/proc.h> 1821541Srgrimes#include <sys/time.h> 1831541Srgrimes#include <sys/types.h> 1841541Srgrimes#include <sys/vnode.h> 1851541Srgrimes#include <sys/mount.h> 1861541Srgrimes#include <sys/namei.h> 1871541Srgrimes#include <sys/malloc.h> 1881541Srgrimes#include <sys/buf.h> 1891541Srgrimes#include <miscfs/nullfs/null.h> 1901541Srgrimes 19112769Sphkstatic int null_bug_bypass = 0; /* for debugging: enables bypass printf'ing */ 19212769SphkSYSCTL_INT(_debug, OID_AUTO, nullfs_bug_bypass, CTLFLAG_RW, 19312769Sphk &null_bug_bypass, 0, ""); 1941541Srgrimes 19522597Smppstatic int null_access __P((struct vop_access_args *ap)); 19622521Sdysonint null_bypass __P((struct vop_generic_args *ap)); 19712769Sphkstatic int null_bwrite __P((struct vop_bwrite_args *ap)); 19812769Sphkstatic int null_getattr __P((struct vop_getattr_args *ap)); 19912769Sphkstatic int null_inactive __P((struct vop_inactive_args *ap)); 20022597Smppstatic int null_lock __P((struct vop_lock_args *ap)); 20122597Smppstatic int null_lookup __P((struct vop_lookup_args *ap)); 20212769Sphkstatic int null_print __P((struct vop_print_args *ap)); 20312769Sphkstatic int null_reclaim __P((struct vop_reclaim_args *ap)); 20422597Smppstatic int null_setattr __P((struct vop_setattr_args *ap)); 20512769Sphkstatic int null_strategy __P((struct vop_strategy_args *ap)); 20622597Smppstatic int null_unlock __P((struct vop_unlock_args *ap)); 20712595Sbde 2081541Srgrimes/* 2091541Srgrimes * This is the 10-Apr-92 bypass routine. 2101541Srgrimes * This version has been optimized for speed, throwing away some 2111541Srgrimes * safety checks. It should still always work, but it's not as 2121541Srgrimes * robust to programmer errors. 2131541Srgrimes * Define SAFETY to include some error checking code. 2141541Srgrimes * 2151541Srgrimes * In general, we map all vnodes going down and unmap them on the way back. 2161541Srgrimes * As an exception to this, vnodes can be marked "unmapped" by setting 2171541Srgrimes * the Nth bit in operation's vdesc_flags. 2181541Srgrimes * 2191541Srgrimes * Also, some BSD vnode operations have the side effect of vrele'ing 2201541Srgrimes * their arguments. With stacking, the reference counts are held 2211541Srgrimes * by the upper node, not the lower one, so we must handle these 2221541Srgrimes * side-effects here. This is not of concern in Sun-derived systems 2231541Srgrimes * since there are no such side-effects. 2241541Srgrimes * 2251541Srgrimes * This makes the following assumptions: 2261541Srgrimes * - only one returned vpp 2271541Srgrimes * - no INOUT vpp's (Sun's vop_open has one of these) 2281541Srgrimes * - the vnode operation vector of the first vnode should be used 2291541Srgrimes * to determine what implementation of the op should be invoked 2301541Srgrimes * - all mapped vnodes are of our vnode-type (NEEDSWORK: 2311541Srgrimes * problems on rmdir'ing mount points and renaming?) 2328876Srgrimes */ 23322521Sdysonint 2341541Srgrimesnull_bypass(ap) 2351541Srgrimes struct vop_generic_args /* { 2361541Srgrimes struct vnodeop_desc *a_desc; 2371541Srgrimes <other random data follows, presumably> 2381541Srgrimes } */ *ap; 2391541Srgrimes{ 2401541Srgrimes register struct vnode **this_vp_p; 2411541Srgrimes int error; 2421541Srgrimes struct vnode *old_vps[VDESC_MAX_VPS]; 2431541Srgrimes struct vnode **vps_p[VDESC_MAX_VPS]; 2441541Srgrimes struct vnode ***vppp; 2451541Srgrimes struct vnodeop_desc *descp = ap->a_desc; 2461541Srgrimes int reles, i; 2471541Srgrimes 2481541Srgrimes if (null_bug_bypass) 2491541Srgrimes printf ("null_bypass: %s\n", descp->vdesc_name); 2501541Srgrimes 2511541Srgrimes#ifdef SAFETY 2521541Srgrimes /* 2531541Srgrimes * We require at least one vp. 2541541Srgrimes */ 2551541Srgrimes if (descp->vdesc_vp_offsets == NULL || 2561541Srgrimes descp->vdesc_vp_offsets[0] == VDESC_NO_OFFSET) 2577170Sdg panic ("null_bypass: no vp's in map."); 2581541Srgrimes#endif 2591541Srgrimes 2601541Srgrimes /* 2611541Srgrimes * Map the vnodes going in. 2621541Srgrimes * Later, we'll invoke the operation based on 2631541Srgrimes * the first mapped vnode's operation vector. 2641541Srgrimes */ 2651541Srgrimes reles = descp->vdesc_flags; 2661541Srgrimes for (i = 0; i < VDESC_MAX_VPS; reles >>= 1, i++) { 2671541Srgrimes if (descp->vdesc_vp_offsets[i] == VDESC_NO_OFFSET) 2681541Srgrimes break; /* bail out at end of list */ 2698876Srgrimes vps_p[i] = this_vp_p = 2701541Srgrimes VOPARG_OFFSETTO(struct vnode**,descp->vdesc_vp_offsets[i],ap); 2711541Srgrimes /* 2721541Srgrimes * We're not guaranteed that any but the first vnode 2731541Srgrimes * are of our type. Check for and don't map any 2741541Srgrimes * that aren't. (We must always map first vp or vclean fails.) 2751541Srgrimes */ 27622521Sdyson if (i && (*this_vp_p == NULL || 27722521Sdyson (*this_vp_p)->v_op != null_vnodeop_p)) { 2781541Srgrimes old_vps[i] = NULL; 2791541Srgrimes } else { 2801541Srgrimes old_vps[i] = *this_vp_p; 2811541Srgrimes *(vps_p[i]) = NULLVPTOLOWERVP(*this_vp_p); 2821541Srgrimes /* 2831541Srgrimes * XXX - Several operations have the side effect 2841541Srgrimes * of vrele'ing their vp's. We must account for 2851541Srgrimes * that. (This should go away in the future.) 2861541Srgrimes */ 2871541Srgrimes if (reles & 1) 2881541Srgrimes VREF(*this_vp_p); 2891541Srgrimes } 2908876Srgrimes 2911541Srgrimes } 2921541Srgrimes 2931541Srgrimes /* 2941541Srgrimes * Call the operation on the lower layer 2951541Srgrimes * with the modified argument structure. 2961541Srgrimes */ 2971541Srgrimes error = VCALL(*(vps_p[0]), descp->vdesc_offset, ap); 2981541Srgrimes 2991541Srgrimes /* 3001541Srgrimes * Maintain the illusion of call-by-value 3011541Srgrimes * by restoring vnodes in the argument structure 3021541Srgrimes * to their original value. 3031541Srgrimes */ 3041541Srgrimes reles = descp->vdesc_flags; 3051541Srgrimes for (i = 0; i < VDESC_MAX_VPS; reles >>= 1, i++) { 3061541Srgrimes if (descp->vdesc_vp_offsets[i] == VDESC_NO_OFFSET) 3071541Srgrimes break; /* bail out at end of list */ 3081541Srgrimes if (old_vps[i]) { 3091541Srgrimes *(vps_p[i]) = old_vps[i]; 3101541Srgrimes if (reles & 1) 3111541Srgrimes vrele(*(vps_p[i])); 3121541Srgrimes } 3131541Srgrimes } 3141541Srgrimes 3151541Srgrimes /* 3161541Srgrimes * Map the possible out-going vpp 3171541Srgrimes * (Assumes that the lower layer always returns 3181541Srgrimes * a VREF'ed vpp unless it gets an error.) 3191541Srgrimes */ 3201541Srgrimes if (descp->vdesc_vpp_offset != VDESC_NO_OFFSET && 3211541Srgrimes !(descp->vdesc_flags & VDESC_NOMAP_VPP) && 3221541Srgrimes !error) { 3231541Srgrimes /* 3241541Srgrimes * XXX - even though some ops have vpp returned vp's, 3251541Srgrimes * several ops actually vrele this before returning. 3261541Srgrimes * We must avoid these ops. 3271541Srgrimes * (This should go away when these ops are regularized.) 3281541Srgrimes */ 3291541Srgrimes if (descp->vdesc_flags & VDESC_VPP_WILLRELE) 3301541Srgrimes goto out; 3311541Srgrimes vppp = VOPARG_OFFSETTO(struct vnode***, 3321541Srgrimes descp->vdesc_vpp_offset,ap); 3331541Srgrimes error = null_node_create(old_vps[0]->v_mount, **vppp, *vppp); 3341541Srgrimes } 3351541Srgrimes 3361541Srgrimes out: 3371541Srgrimes return (error); 3381541Srgrimes} 3391541Srgrimes 34022521Sdyson/* 34122521Sdyson * We have to carry on the locking protocol on the null layer vnodes 34222521Sdyson * as we progress through the tree. We also have to enforce read-only 34322521Sdyson * if this layer is mounted read-only. 34422521Sdyson */ 34522521Sdysonstatic int 34622521Sdysonnull_lookup(ap) 34722521Sdyson struct vop_lookup_args /* { 34822521Sdyson struct vnode * a_dvp; 34922521Sdyson struct vnode ** a_vpp; 35022521Sdyson struct componentname * a_cnp; 35122521Sdyson } */ *ap; 35222521Sdyson{ 35322521Sdyson struct componentname *cnp = ap->a_cnp; 35422521Sdyson struct proc *p = cnp->cn_proc; 35522521Sdyson int flags = cnp->cn_flags; 35622521Sdyson struct vop_lock_args lockargs; 35722521Sdyson struct vop_unlock_args unlockargs; 35822521Sdyson struct vnode *dvp, *vp; 35922521Sdyson int error; 3601541Srgrimes 36122521Sdyson if ((flags & ISLASTCN) && (ap->a_dvp->v_mount->mnt_flag & MNT_RDONLY) && 36222521Sdyson (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) 36322521Sdyson return (EROFS); 36422607Smpp error = null_bypass((struct vop_generic_args *)ap); 36522521Sdyson if (error == EJUSTRETURN && (flags & ISLASTCN) && 36622521Sdyson (ap->a_dvp->v_mount->mnt_flag & MNT_RDONLY) && 36722521Sdyson (cnp->cn_nameiop == CREATE || cnp->cn_nameiop == RENAME)) 36822521Sdyson error = EROFS; 36922521Sdyson /* 37022521Sdyson * We must do the same locking and unlocking at this layer as 37122521Sdyson * is done in the layers below us. We could figure this out 37222521Sdyson * based on the error return and the LASTCN, LOCKPARENT, and 37322521Sdyson * LOCKLEAF flags. However, it is more expidient to just find 37422521Sdyson * out the state of the lower level vnodes and set ours to the 37522521Sdyson * same state. 37622521Sdyson */ 37722521Sdyson dvp = ap->a_dvp; 37822521Sdyson vp = *ap->a_vpp; 37922521Sdyson if (dvp == vp) 38022521Sdyson return (error); 38122521Sdyson if (!VOP_ISLOCKED(dvp)) { 38222521Sdyson unlockargs.a_vp = dvp; 38322521Sdyson unlockargs.a_flags = 0; 38422521Sdyson unlockargs.a_p = p; 38522521Sdyson vop_nounlock(&unlockargs); 38622521Sdyson } 38722521Sdyson if (vp != NULL && VOP_ISLOCKED(vp)) { 38822521Sdyson lockargs.a_vp = vp; 38922521Sdyson lockargs.a_flags = LK_SHARED; 39022521Sdyson lockargs.a_p = p; 39122521Sdyson vop_nolock(&lockargs); 39222521Sdyson } 39322521Sdyson return (error); 39422521Sdyson} 39522521Sdyson 3961541Srgrimes/* 39722521Sdyson * Setattr call. Disallow write attempts if the layer is mounted read-only. 39822521Sdyson */ 39922521Sdysonint 40022521Sdysonnull_setattr(ap) 40122521Sdyson struct vop_setattr_args /* { 40222521Sdyson struct vnodeop_desc *a_desc; 40322521Sdyson struct vnode *a_vp; 40422521Sdyson struct vattr *a_vap; 40522521Sdyson struct ucred *a_cred; 40622521Sdyson struct proc *a_p; 40722521Sdyson } */ *ap; 40822521Sdyson{ 40922521Sdyson struct vnode *vp = ap->a_vp; 41022521Sdyson struct vattr *vap = ap->a_vap; 41122521Sdyson 41222521Sdyson if ((vap->va_flags != VNOVAL || vap->va_uid != (uid_t)VNOVAL || 41322597Smpp vap->va_gid != (gid_t)VNOVAL || vap->va_atime.tv_sec != VNOVAL || 41422597Smpp vap->va_mtime.tv_sec != VNOVAL || vap->va_mode != (mode_t)VNOVAL) && 41522521Sdyson (vp->v_mount->mnt_flag & MNT_RDONLY)) 41622521Sdyson return (EROFS); 41722521Sdyson if (vap->va_size != VNOVAL) { 41822521Sdyson switch (vp->v_type) { 41922521Sdyson case VDIR: 42022521Sdyson return (EISDIR); 42122521Sdyson case VCHR: 42222521Sdyson case VBLK: 42322521Sdyson case VSOCK: 42422521Sdyson case VFIFO: 42522521Sdyson return (0); 42622521Sdyson case VREG: 42722521Sdyson case VLNK: 42822521Sdyson default: 42922521Sdyson /* 43022521Sdyson * Disallow write attempts if the filesystem is 43122521Sdyson * mounted read-only. 43222521Sdyson */ 43322521Sdyson if (vp->v_mount->mnt_flag & MNT_RDONLY) 43422521Sdyson return (EROFS); 43522521Sdyson } 43622521Sdyson } 43722607Smpp return (null_bypass((struct vop_generic_args *)ap)); 43822521Sdyson} 43922521Sdyson 44022521Sdyson/* 4411541Srgrimes * We handle getattr only to change the fsid. 4421541Srgrimes */ 44312769Sphkstatic int 4441541Srgrimesnull_getattr(ap) 4451541Srgrimes struct vop_getattr_args /* { 4461541Srgrimes struct vnode *a_vp; 4471541Srgrimes struct vattr *a_vap; 4481541Srgrimes struct ucred *a_cred; 4491541Srgrimes struct proc *a_p; 4501541Srgrimes } */ *ap; 4511541Srgrimes{ 4521541Srgrimes int error; 45322521Sdyson 45422607Smpp if (error = null_bypass((struct vop_generic_args *)ap)) 4551541Srgrimes return (error); 4561541Srgrimes /* Requires that arguments be restored. */ 4571541Srgrimes ap->a_vap->va_fsid = ap->a_vp->v_mount->mnt_stat.f_fsid.val[0]; 4581541Srgrimes return (0); 4591541Srgrimes} 4601541Srgrimes 46122521Sdysonstatic int 46222521Sdysonnull_access(ap) 46322521Sdyson struct vop_access_args /* { 46422521Sdyson struct vnode *a_vp; 46522521Sdyson int a_mode; 46622521Sdyson struct ucred *a_cred; 46722521Sdyson struct proc *a_p; 46822521Sdyson } */ *ap; 46922521Sdyson{ 47022521Sdyson struct vnode *vp = ap->a_vp; 47122521Sdyson mode_t mode = ap->a_mode; 4721541Srgrimes 47322521Sdyson /* 47422521Sdyson * Disallow write attempts on read-only layers; 47522521Sdyson * unless the file is a socket, fifo, or a block or 47622521Sdyson * character device resident on the file system. 47722521Sdyson */ 47822521Sdyson if (mode & VWRITE) { 47922521Sdyson switch (vp->v_type) { 48022521Sdyson case VDIR: 48122521Sdyson case VLNK: 48222521Sdyson case VREG: 48322521Sdyson if (vp->v_mount->mnt_flag & MNT_RDONLY) 48422521Sdyson return (EROFS); 48522521Sdyson break; 48622521Sdyson } 48722521Sdyson } 48822607Smpp return (null_bypass((struct vop_generic_args *)ap)); 48922521Sdyson} 49022521Sdyson 49122521Sdyson/* 49222521Sdyson * We need to process our own vnode lock and then clear the 49322521Sdyson * interlock flag as it applies only to our vnode, not the 49422521Sdyson * vnodes below us on the stack. 49522521Sdyson */ 49622597Smppstatic int 49722521Sdysonnull_lock(ap) 49822521Sdyson struct vop_lock_args /* { 49922521Sdyson struct vnode *a_vp; 50022521Sdyson int a_flags; 50122521Sdyson struct proc *a_p; 50222521Sdyson } */ *ap; 50322521Sdyson{ 50422521Sdyson 50522521Sdyson vop_nolock(ap); 50622521Sdyson if ((ap->a_flags & LK_TYPE_MASK) == LK_DRAIN) 50722521Sdyson return (0); 50822521Sdyson ap->a_flags &= ~LK_INTERLOCK; 50922607Smpp return (null_bypass((struct vop_generic_args *)ap)); 51022521Sdyson} 51122521Sdyson 51222521Sdyson/* 51322521Sdyson * We need to process our own vnode unlock and then clear the 51422521Sdyson * interlock flag as it applies only to our vnode, not the 51522521Sdyson * vnodes below us on the stack. 51622521Sdyson */ 51722597Smppstatic int 51822521Sdysonnull_unlock(ap) 51922521Sdyson struct vop_unlock_args /* { 52022521Sdyson struct vnode *a_vp; 52122521Sdyson int a_flags; 52222521Sdyson struct proc *a_p; 52322521Sdyson } */ *ap; 52422521Sdyson{ 52522521Sdyson struct vnode *vp = ap->a_vp; 52622521Sdyson 52722521Sdyson vop_nounlock(ap); 52822521Sdyson ap->a_flags &= ~LK_INTERLOCK; 52922607Smpp return (null_bypass((struct vop_generic_args *)ap)); 53022521Sdyson} 53122521Sdyson 53222597Smppstatic int 5331541Srgrimesnull_inactive(ap) 5341541Srgrimes struct vop_inactive_args /* { 5351541Srgrimes struct vnode *a_vp; 53622521Sdyson struct proc *a_p; 5371541Srgrimes } */ *ap; 5381541Srgrimes{ 5391541Srgrimes /* 5401541Srgrimes * Do nothing (and _don't_ bypass). 5411541Srgrimes * Wait to vrele lowervp until reclaim, 5421541Srgrimes * so that until then our null_node is in the 5431541Srgrimes * cache and reusable. 5441541Srgrimes * 5451541Srgrimes * NEEDSWORK: Someday, consider inactive'ing 5461541Srgrimes * the lowervp and then trying to reactivate it 5471541Srgrimes * with capabilities (v_id) 5481541Srgrimes * like they do in the name lookup cache code. 5491541Srgrimes * That's too much work for now. 5501541Srgrimes */ 55122521Sdyson VOP_UNLOCK(ap->a_vp, 0, ap->a_p); 5521541Srgrimes return (0); 5531541Srgrimes} 5541541Srgrimes 55512769Sphkstatic int 5561541Srgrimesnull_reclaim(ap) 5571541Srgrimes struct vop_reclaim_args /* { 5581541Srgrimes struct vnode *a_vp; 55922521Sdyson struct proc *a_p; 5601541Srgrimes } */ *ap; 5611541Srgrimes{ 5621541Srgrimes struct vnode *vp = ap->a_vp; 5631541Srgrimes struct null_node *xp = VTONULL(vp); 5641541Srgrimes struct vnode *lowervp = xp->null_lowervp; 5651541Srgrimes 5661541Srgrimes /* 5671541Srgrimes * Note: in vop_reclaim, vp->v_op == dead_vnodeop_p, 5681541Srgrimes * so we can't call VOPs on ourself. 5691541Srgrimes */ 5701541Srgrimes /* After this assignment, this node will not be re-used. */ 5711541Srgrimes xp->null_lowervp = NULL; 57222521Sdyson LIST_REMOVE(xp, null_hash); 5731541Srgrimes FREE(vp->v_data, M_TEMP); 5741541Srgrimes vp->v_data = NULL; 5751541Srgrimes vrele (lowervp); 5761541Srgrimes return (0); 5771541Srgrimes} 5781541Srgrimes 57912769Sphkstatic int 5801541Srgrimesnull_print(ap) 5811541Srgrimes struct vop_print_args /* { 5821541Srgrimes struct vnode *a_vp; 5831541Srgrimes } */ *ap; 5841541Srgrimes{ 5851541Srgrimes register struct vnode *vp = ap->a_vp; 5863496Sphk printf ("\ttag VT_NULLFS, vp=%p, lowervp=%p\n", vp, NULLVPTOLOWERVP(vp)); 5871541Srgrimes return (0); 5881541Srgrimes} 5891541Srgrimes 5901541Srgrimes/* 5911541Srgrimes * XXX - vop_strategy must be hand coded because it has no 5921541Srgrimes * vnode in its arguments. 5931541Srgrimes * This goes away with a merged VM/buffer cache. 5941541Srgrimes */ 59512769Sphkstatic int 5961541Srgrimesnull_strategy(ap) 5971541Srgrimes struct vop_strategy_args /* { 5981541Srgrimes struct buf *a_bp; 5991541Srgrimes } */ *ap; 6001541Srgrimes{ 6011541Srgrimes struct buf *bp = ap->a_bp; 6021541Srgrimes int error; 6031541Srgrimes struct vnode *savedvp; 6041541Srgrimes 6051541Srgrimes savedvp = bp->b_vp; 6061541Srgrimes bp->b_vp = NULLVPTOLOWERVP(bp->b_vp); 6071541Srgrimes 6081541Srgrimes error = VOP_STRATEGY(bp); 6091541Srgrimes 6101541Srgrimes bp->b_vp = savedvp; 6111541Srgrimes 6121541Srgrimes return (error); 6131541Srgrimes} 6141541Srgrimes 6151541Srgrimes/* 6161541Srgrimes * XXX - like vop_strategy, vop_bwrite must be hand coded because it has no 6171541Srgrimes * vnode in its arguments. 6181541Srgrimes * This goes away with a merged VM/buffer cache. 6191541Srgrimes */ 62012769Sphkstatic int 6211541Srgrimesnull_bwrite(ap) 6221541Srgrimes struct vop_bwrite_args /* { 6231541Srgrimes struct buf *a_bp; 6241541Srgrimes } */ *ap; 6251541Srgrimes{ 6261541Srgrimes struct buf *bp = ap->a_bp; 6271541Srgrimes int error; 6281541Srgrimes struct vnode *savedvp; 6291541Srgrimes 6301541Srgrimes savedvp = bp->b_vp; 6311541Srgrimes bp->b_vp = NULLVPTOLOWERVP(bp->b_vp); 6321541Srgrimes 6331541Srgrimes error = VOP_BWRITE(bp); 6341541Srgrimes 6351541Srgrimes bp->b_vp = savedvp; 6361541Srgrimes 6371541Srgrimes return (error); 6381541Srgrimes} 6391541Srgrimes 6401541Srgrimes/* 6411541Srgrimes * Global vfs data structures 6421541Srgrimes */ 64312158Sbdevop_t **null_vnodeop_p; 64412769Sphkstatic struct vnodeopv_entry_desc null_vnodeop_entries[] = { 64512158Sbde { &vop_default_desc, (vop_t *)null_bypass }, 6461541Srgrimes 64722521Sdyson { &vop_lookup_desc, (vop_t *)null_lookup }, 64822521Sdyson { &vop_setattr_desc, (vop_t *)null_setattr }, 64912158Sbde { &vop_getattr_desc, (vop_t *)null_getattr }, 65022521Sdyson { &vop_access_desc, (vop_t *)null_access }, 65122521Sdyson { &vop_lock_desc, (vop_t *)null_lock }, 65222521Sdyson { &vop_unlock_desc, (vop_t *)null_unlock }, 65312158Sbde { &vop_inactive_desc, (vop_t *)null_inactive }, 65412158Sbde { &vop_reclaim_desc, (vop_t *)null_reclaim }, 65512158Sbde { &vop_print_desc, (vop_t *)null_print }, 6561541Srgrimes 65712158Sbde { &vop_strategy_desc, (vop_t *)null_strategy }, 65812158Sbde { &vop_bwrite_desc, (vop_t *)null_bwrite }, 6591541Srgrimes 66012158Sbde { NULL, NULL } 6611541Srgrimes}; 66212769Sphkstatic struct vnodeopv_desc null_vnodeop_opv_desc = 6631541Srgrimes { &null_vnodeop_p, null_vnodeop_entries }; 6642946Swollman 6652946SwollmanVNODEOP_SET(null_vnodeop_opv_desc); 666