X-Git-Url: https://git.saurik.com/apple/xnu.git/blobdiff_plain/060df5ea7c632b1ac8cc8aac1fb59758165c2084..6d2010ae8f7a6078e10b361c6962983bab233e0f:/bsd/miscfs/nullfs/null_vnops.c?ds=inline diff --git a/bsd/miscfs/nullfs/null_vnops.c b/bsd/miscfs/nullfs/null_vnops.c deleted file mode 100644 index 4b2fb2bbf..000000000 --- a/bsd/miscfs/nullfs/null_vnops.c +++ /dev/null @@ -1,570 +0,0 @@ -/* - * Copyright (c) 2000 Apple Computer, Inc. All rights reserved. - * - * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ - * - * This file contains Original Code and/or Modifications of Original Code - * as defined in and that are subject to the Apple Public Source License - * Version 2.0 (the 'License'). You may not use this file except in - * compliance with the License. The rights granted to you under the License - * may not be used to create, or enable the creation or redistribution of, - * unlawful or unlicensed copies of an Apple operating system, or to - * circumvent, violate, or enable the circumvention or violation of, any - * terms of an Apple operating system software license agreement. - * - * Please obtain a copy of the License at - * http://www.opensource.apple.com/apsl/ and read it before using this file. - * - * The Original Code and all software distributed under the License are - * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER - * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, - * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, - * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. - * Please see the License for the specific language governing rights and - * limitations under the License. - * - * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ - */ -/* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */ -/* - * Copyright (c) 1992, 1993 - * The Regents of the University of California. All rights reserved. - * - * This code is derived from software contributed to Berkeley by - * John Heidemann of the UCLA Ficus project. - * - * Redistribution and use in source and binary forms, with or without - * modification, are permitted provided that the following conditions - * are met: - * 1. Redistributions of source code must retain the above copyright - * notice, this list of conditions and the following disclaimer. - * 2. Redistributions in binary form must reproduce the above copyright - * notice, this list of conditions and the following disclaimer in the - * documentation and/or other materials provided with the distribution. - * 3. All advertising materials mentioning features or use of this software - * must display the following acknowledgement: - * This product includes software developed by the University of - * California, Berkeley and its contributors. - * 4. Neither the name of the University nor the names of its contributors - * may be used to endorse or promote products derived from this software - * without specific prior written permission. - * - * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND - * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE - * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE - * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE - * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL - * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS - * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) - * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT - * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY - * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF - * SUCH DAMAGE. - * - * @(#)null_vnops.c 8.6 (Berkeley) 5/27/95 - * - * Ancestors: - * @(#)lofs_vnops.c 1.2 (Berkeley) 6/18/92 - * ...and... - * @(#)null_vnodeops.c 1.20 92/07/07 UCLA Ficus project - */ - -/* - * Null Layer - * - * (See mount_null(8) for more information.) - * - * The null layer duplicates a portion of the file system - * name space under a new name. In this respect, it is - * similar to the loopback file system. It differs from - * the loopback fs in two respects: it is implemented using - * a stackable layers techniques, and it's "null-node"s stack above - * all lower-layer vnodes, not just over directory vnodes. - * - * The null layer has two purposes. First, it serves as a demonstration - * of layering by proving a layer which does nothing. (It actually - * does everything the loopback file system does, which is slightly - * more than nothing.) Second, the null layer can serve as a prototype - * layer. Since it provides all necessary layer framework, - * new file system layers can be created very easily be starting - * with a null layer. - * - * The remainder of this man page examines the null layer as a basis - * for constructing new layers. - * - * - * INSTANTIATING NEW NULL LAYERS - * - * New null layers are created with mount_null(8). - * Mount_null(8) takes two arguments, the pathname - * of the lower vfs (target-pn) and the pathname where the null - * layer will appear in the namespace (alias-pn). After - * the null layer is put into place, the contents - * of target-pn subtree will be aliased under alias-pn. - * - * - * OPERATION OF A NULL LAYER - * - * The null layer is the minimum file system layer, - * simply bypassing all possible operations to the lower layer - * for processing there. The majority of its activity centers - * on the bypass routine, though which nearly all vnode operations - * pass. - * - * The bypass routine accepts arbitrary vnode operations for - * handling by the lower layer. It begins by examing vnode - * operation arguments and replacing any null-nodes by their - * lower-layer equivlants. It then invokes the operation - * on the lower layer. Finally, it replaces the null-nodes - * in the arguments and, if a vnode is return by the operation, - * stacks a null-node on top of the returned vnode. - * - * Although bypass handles most operations, vnop_getattr, vnop_lock, - * vnop_unlock, vnop_inactive, vnop_reclaim, and vnop_print are not - * bypassed. Vop_getattr must change the fsid being returned. - * Vop_lock and vnop_unlock must handle any locking for the - * current vnode as well as pass the lock request down. - * Vop_inactive and vnop_reclaim are not bypassed so that - * they can handle freeing null-layer specific data. Vop_print - * is not bypassed to avoid excessive debugging information. - * Also, certain vnode operations change the locking state within - * the operation (create, mknod, remove, link, rename, mkdir, rmdir, - * and symlink). Ideally these operations should not change the - * lock state, but should be changed to let the caller of the - * function unlock them. Otherwise all intermediate vnode layers - * (such as union, umapfs, etc) must catch these functions to do - * the necessary locking at their layer. - * - * - * INSTANTIATING VNODE STACKS - * - * Mounting associates the null layer with a lower layer, - * effect stacking two VFSes. Vnode stacks are instead - * created on demand as files are accessed. - * - * The initial mount creates a single vnode stack for the - * root of the new null layer. All other vnode stacks - * are created as a result of vnode operations on - * this or other null vnode stacks. - * - * New vnode stacks come into existance as a result of - * an operation which returns a vnode. - * The bypass routine stacks a null-node above the new - * vnode before returning it to the caller. - * - * For example, imagine mounting a null layer with - * "mount_null /usr/include /dev/layer/null". - * Changing directory to /dev/layer/null will assign - * the root null-node (which was created when the null layer was mounted). - * Now consider opening "sys". A vnop_lookup would be - * done on the root null-node. This operation would bypass through - * to the lower layer which would return a vnode representing - * the UFS "sys". Null_bypass then builds a null-node - * aliasing the UFS "sys" and returns this to the caller. - * Later operations on the null-node "sys" will repeat this - * process when constructing other vnode stacks. - * - * - * CREATING OTHER FILE SYSTEM LAYERS - * - * One of the easiest ways to construct new file system layers is to make - * a copy of the null layer, rename all files and variables, and - * then begin modifing the copy. Sed can be used to easily rename - * all variables. - * - * The umap layer is an example of a layer descended from the - * null layer. - * - * - * INVOKING OPERATIONS ON LOWER LAYERS - * - * There are two techniques to invoke operations on a lower layer - * when the operation cannot be completely bypassed. Each method - * is appropriate in different situations. In both cases, - * it is the responsibility of the aliasing layer to make - * the operation arguments "correct" for the lower layer - * by mapping an vnode arguments to the lower layer. - * - * The first approach is to call the aliasing layer's bypass routine. - * This method is most suitable when you wish to invoke the operation - * currently being hanldled on the lower layer. It has the advantage - * that the bypass routine already must do argument mapping. - * An example of this is null_getattrs in the null layer. - * - * A second approach is to directly invoked vnode operations on - * the lower layer with the VOP_OPERATIONNAME interface. - * The advantage of this method is that it is easy to invoke - * arbitrary operations on the lower layer. The disadvantage - * is that vnodes arguments must be manualy mapped. - * - */ - -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include -#include - - -int null_bug_bypass = 0; /* for debugging: enables bypass printf'ing */ - -/* - * This is the 10-Apr-92 bypass routine. - * This version has been optimized for speed, throwing away some - * safety checks. It should still always work, but it's not as - * robust to programmer errors. - * Define SAFETY to include some error checking code. - * - * In general, we map all vnodes going down and unmap them on the way back. - * As an exception to this, vnodes can be marked "unmapped" by setting - * the Nth bit in operation's vdesc_flags. - * - * Also, some BSD vnode operations have the side effect of node_put'ing - * their arguments. With stacking, the reference counts are held - * by the upper node, not the lower one, so we must handle these - * side-effects here. This is not of concern in Sun-derived systems - * since there are no such side-effects. - * - * This makes the following assumptions: - * - only one returned vpp - * - no INOUT vpp's (Sun's vnop_open has one of these) - * - the vnode operation vector of the first vnode should be used - * to determine what implementation of the op should be invoked - * - all mapped vnodes are of our vnode-type (NEEDSWORK: - * problems on rmdir'ing mount points and renaming?) - */ -int -null_bypass(ap) - struct vnop_generic_args /* { - struct vnodeop_desc *a_desc; - - } */ *ap; -{ - extern int (**null_vnodeop_p)(void *); /* not extern, really "forward" */ - register struct vnode **this_vp_p; - int error; - struct vnode *old_vps[VDESC_MAX_VPS]; - struct vnode **vps_p[VDESC_MAX_VPS]; - struct vnode ***vppp; - struct vnodeop_desc *descp = ap->a_desc; - int reles, i; - - if (null_bug_bypass) - printf ("null_bypass: %s\n", descp->vdesc_name); - -#ifdef SAFETY - /* - * We require at least one vp. - */ - if (descp->vdesc_vp_offsets == NULL || - descp->vdesc_vp_offsets[0] == VDESC_NO_OFFSET) - panic ("null_bypass: no vp's in map.\n"); -#endif - - /* - * Map the vnodes going in. - * Later, we'll invoke the operation based on - * the first mapped vnode's operation vector. - */ - reles = descp->vdesc_flags; - for (i = 0; i < VDESC_MAX_VPS; reles >>= 1, i++) { - if (descp->vdesc_vp_offsets[i] == VDESC_NO_OFFSET) - break; /* bail out at end of list */ - vps_p[i] = this_vp_p = - VOPARG_OFFSETTO(struct vnode**,descp->vdesc_vp_offsets[i],ap); - /* - * We're not guaranteed that any but the first vnode - * are of our type. Check for and don't map any - * that aren't. (We must always map first vp or vclean fails.) - */ - if (i && (*this_vp_p == NULL || - (*this_vp_p)->v_op != null_vnodeop_p)) { - old_vps[i] = NULL; - } else { - old_vps[i] = *this_vp_p; - *(vps_p[i]) = NULLVPTOLOWERVP(*this_vp_p); - /* - * XXX - Several operations have the side effect - * of vnode_put'ing their vp's. We must account for - * that. (This should go away in the future.) - */ - if (reles & 1) - vnode_get(*this_vp_p); - } - - } - - /* - * Call the operation on the lower layer - * with the modified argument structure. - */ - error = VCALL(*(vps_p[0]), descp->vdesc_offset, ap); - - /* - * Maintain the illusion of call-by-value - * by restoring vnodes in the argument structure - * to their original value. - */ - reles = descp->vdesc_flags; - for (i = 0; i < VDESC_MAX_VPS; reles >>= 1, i++) { - if (descp->vdesc_vp_offsets[i] == VDESC_NO_OFFSET) - break; /* bail out at end of list */ - if (old_vps[i]) { - *(vps_p[i]) = old_vps[i]; - if (reles & 1) - vnode_put(*(vps_p[i])); - } - } - - /* - * Map the possible out-going vpp - * (Assumes that the lower layer always returns - * a vnode_get'ed vpp unless it gets an error.) - */ - if (descp->vdesc_vpp_offset != VDESC_NO_OFFSET && - !(descp->vdesc_flags & VDESC_NOMAP_VPP) && - !error) { - /* - * XXX - even though some ops have vpp returned vp's, - * several ops actually vnode_put this before returning. - * We must avoid these ops. - * (This should go away when these ops are regularized.) - */ - if (descp->vdesc_flags & VDESC_VPP_WILLRELE) - goto out; - vppp = VOPARG_OFFSETTO(struct vnode***, - descp->vdesc_vpp_offset,ap); - error = null_node_create(old_vps[0]->v_mount, **vppp, *vppp); - } - - out: - return (error); -} - -/* - * We have to carry on the locking protocol on the null layer vnodes - * as we progress through the tree. We also have to enforce read-only - * if this layer is mounted read-only. - */ -null_lookup(ap) - struct vnop_lookup_args /* { - struct vnode * a_dvp; - struct vnode ** a_vpp; - struct componentname * a_cnp; - vfs_context_t a_context; - } */ *ap; -{ - struct componentname *cnp = ap->a_cnp; - struct proc *p = cnp->cn_proc; - int flags = cnp->cn_flags; - struct vnode *dvp, *vp; - int error; - - error = null_bypass(ap); - - /* - * We must do the same locking and unlocking at this layer as - * is done in the layers below us. We could figure this out - * based on the error return and the LASTCN, LOCKPARENT, and - * LOCKLEAF flags. However, it is more expidient to just find - * out the state of the lower level vnodes and set ours to the - * same state. - */ - dvp = ap->a_dvp; - vp = *ap->a_vpp; - if (dvp == vp) - return (error); - return (error); -} - -/* - * Setattr call. - */ -int -null_setattr( - struct vnop_setattr_args /* { - struct vnodeop_desc *a_desc; - struct vnode *a_vp; - struct vnode_attr *a_vap; - kauth_cred_t a_cred; - struct proc *a_p; - } */ *ap) -{ - struct vnode *vp = ap->a_vp; - struct vnode_attr *vap = ap->a_vap; - - if (VATTR_IS_ACTIVE(vap, va_data_size)) { - switch (vp->v_type) { - case VDIR: - return (EISDIR); - case VCHR: - case VBLK: - case VSOCK: - case VFIFO: - return (0); - case VREG: - case VLNK: - default: - } - } - return (null_bypass(ap)); -} - -/* - * We handle getattr only to change the fsid. - */ -int -null_getattr(ap) - struct vnop_getattr_args /* { - struct vnode *a_vp; - struct vnode_attr *a_vap; - vfs_context_t a_context; - } */ *ap; -{ - int error; - - if (error = null_bypass(ap)) - return (error); - /* Requires that arguments be restored. */ - VATTR_RETURN(ap->a_vap, va_fsid, ap->a_vp->v_mount->mnt_vfsstat.f_fsid.val[0]); - return (0); -} - -int -null_access(ap) - struct vnop_access_args /* { - struct vnode *a_vp; - int a_action; - vfs_context_t a_context; - } */ *ap; -{ - return (null_bypass(ap)); -} - -int -null_inactive(ap) - struct vnop_inactive_args /* { - struct vnode *a_vp; - vfs_context_t a_context; - } */ *ap; -{ - /* - * Do nothing (and _don't_ bypass). - * Wait to vnode_put lowervp until reclaim, - * so that until then our null_node is in the - * cache and reusable. - * - * NEEDSWORK: Someday, consider inactive'ing - * the lowervp and then trying to reactivate it - * with capabilities (v_id) - * like they do in the name lookup cache code. - * That's too much work for now. - */ - return (0); -} - -int -null_reclaim(ap) - struct vnop_reclaim_args /* { - struct vnode *a_vp; - vfs_context_t a_context; - } */ *ap; -{ - struct vnode *vp = ap->a_vp; - struct null_node *xp = VTONULL(vp); - struct vnode *lowervp = xp->null_lowervp; - - /* - * Note: in vnop_reclaim, vp->v_op == dead_vnodeop_p, - * so we can't call VOPs on ourself. - */ - /* After this assignment, this node will not be re-used. */ - xp->null_lowervp = NULL; - LIST_REMOVE(xp, null_hash); - FREE(vp->v_data, M_TEMP); - vp->v_data = NULL; - vnode_put (lowervp); - return (0); -} - -/* - * XXX - vnop_strategy must be hand coded because it has no - * vnode in its arguments. - * This goes away with a merged VM/buffer cache. - */ -int -null_strategy(ap) - struct vnop_strategy_args /* { - struct buf *a_bp; - } */ *ap; -{ - struct buf *bp = ap->a_bp; - int error; - struct vnode *savedvp; - - savedvp = vnode(bp); - buf_setvnode(bp, NULLVPTOLOWERVP(savedvp)); - - error = VNOP_STRATEGY(bp); - - buf_setvnode(bp, savedvp); - - return (error); -} - -/* - * XXX - like vnop_strategy, vnop_bwrite must be hand coded because it has no - * vnode in its arguments. - * This goes away with a merged VM/buffer cache. - */ -int -null_bwrite(ap) - struct vnop_bwrite_args /* { - struct buf *a_bp; - } */ *ap; -{ - struct buf *bp = ap->a_bp; - int error; - struct vnode *savedvp; - - savedvp = buf_vnode(bp); - buf_setvnode(bp, NULLVPTOLOWERVP(savedvp)); - - error = VNOP_BWRITE(bp); - - buf_setvnode(bp, savedvp); - - return (error); -} - -/* - * Global vfs data structures - */ - -#define VOPFUNC int (*)(void *) - -int (**null_vnodeop_p)(void *); -struct vnodeopv_entry_desc null_vnodeop_entries[] = { - { &vnop_default_desc, (VOPFUNC)null_bypass }, - - { &vnop_lookup_desc, (VOPFUNC)null_lookup }, - { &vnop_setattr_desc, (VOPFUNC)null_setattr }, - { &vnop_getattr_desc, (VOPFUNC)null_getattr }, - { &vnop_access_desc, (VOPFUNC)null_access }, - { &vnop_inactive_desc, (VOPFUNC)null_inactive }, - { &vnop_reclaim_desc, (VOPFUNC)null_reclaim }, - - { &vnop_strategy_desc, (VOPFUNC)null_strategy }, - { &vnop_bwrite_desc, (VOPFUNC)null_bwrite }, - - { (struct vnodeop_desc*)NULL, (int(*)())NULL } -}; -struct vnodeopv_desc null_vnodeop_opv_desc = - { &null_vnodeop_p, null_vnodeop_entries };