/* $NetBSD: layer_vnops.c,v 1.3 2000/03/30 12:22:14 augustss Exp $ */ /* * Copyright (c) 1999 National Aeronautics & Space Administration * All rights reserved. * * This software was written by William Studenmund of the * Numerical Aerospace Similation Facility, NASA Ames Research Center. * * 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. Neither the name of the National Aeronautics & Space Administration * 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 NATIONAL AERONAUTICS & SPACE ADMINISTRATION * ``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 ADMINISTRATION OR CONTRIB- * UTORS 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. */ /* * 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 * $Id: layer_vnops.c,v 1.3 2000/03/30 12:22:14 augustss Exp $ * ...and... * @(#)null_vnodeops.c 1.20 92/07/07 UCLA Ficus project */ /* * Null Layer vnode routines. * * (See mount_null(8) for more information.) * * The layer.h, layer_extern.h, layer_vfs.c, and layer_vnops.c files provide * the core implimentation of the null file system and most other stacked * fs's. The description below refers to the null file system, but the * services provided by the layer* files are useful for all layered fs's. * * 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 the 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. * * It is conceivable that other overlay filesystems will take different * parameters. For instance, data migration or access controll layers might * only take one pathname which will serve both as the target-pn and * alias-pn described above. * * * 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 layered nodes by their * lower-layer equivlants. It then invokes the operation * on the lower layer. Finally, it replaces the layered nodes * in the arguments and, if a vnode is return by the operation, * stacks a layered node on top of the returned vnode. * * The bypass routine in this file, layer_bypass(), is suitable for use * by many different layered filesystems. It can be used by multiple * filesystems simultaneously. Alternatively, a layered fs may provide * its own bypass routine, in which case layer_bypass() should be used as * a model. For instance, the main functionality provided by umapfs, the user * identity mapping file system, is handled by a custom bypass routine. * * Typically a layered fs registers its selected bypass routine as the * default vnode operation in its vnodeopv_entry_desc table. Additionally * the filesystem must store the bypass entry point in the layerm_bypass * field of struct layer_mount. All other layer routines in this file will * use the layerm_bypass routine. * * Although the bypass routine handles most operations outright, a number * of operations are special cased, and handled by the layered fs. One * group, layer_setattr, layer_getattr, layer_access, layer_open, and * layer_fsync, perform layer-specific manipulation in addition to calling * the bypass routine. The other group * Although bypass handles most operations, vop_getattr, vop_lock, * vop_unlock, vop_inactive, vop_reclaim, and vop_print are not * bypassed. Vop_getattr must change the fsid being returned. * Vop_lock and vop_unlock must handle any locking for the * current vnode as well as pass the lock request down. * Vop_inactive and vop_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 vop_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". layer_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 #include /* * This is the 08-June-99 bypass routine, based on the 10-Apr-92 bypass * routine by John Heidemann. * The new element for this version is that the whole nullfs * system gained the concept of locks on the lower node, and locks on * our nodes. When returning from a call to the lower layer, we may * need to update lock state ONLY on our layer. The LAYERFS_UPPER*LOCK() * macros provide this functionality. * The 10-Apr-92 version was 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. * * Also, some BSD vnode operations have the side effect of vrele'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. * * New for the 08-June-99 version: we also handle operations which unlock * the passed-in node (typically they vput the node). * * This makes the following assumptions: * - only one returned vpp * - no INOUT vpp's (Sun's vop_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 layer_bypass(v) void *v; { struct vop_generic_args /* { struct vnodeop_desc *a_desc; } */ *ap = v; int (**our_vnodeop_p) __P((void *)); struct vnode **this_vp_p; int error, error1; struct vnode *old_vps[VDESC_MAX_VPS], *vp0; struct vnode **vps_p[VDESC_MAX_VPS]; struct vnode ***vppp; struct vnodeop_desc *descp = ap->a_desc; int reles, i, flags; #ifdef SAFETY /* * We require at least one vp. */ if (descp->vdesc_vp_offsets == NULL || descp->vdesc_vp_offsets[0] == VDESC_NO_OFFSET) panic ("layer_bypass: no vp's in map.\n"); #endif vps_p[0] = VOPARG_OFFSETTO(struct vnode**,descp->vdesc_vp_offsets[0],ap); vp0 = *vps_p[0]; flags = MOUNTTOLAYERMOUNT(vp0->v_mount)->layerm_flags; our_vnodeop_p = vp0->v_op; if (flags & LAYERFS_MBYPASSDEBUG) printf ("layer_bypass: %s\n", descp->vdesc_name); /* * 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 != our_vnodeop_p)) { old_vps[i] = NULL; } else { old_vps[i] = *this_vp_p; *(vps_p[i]) = LAYERVPTOLOWERVP(*this_vp_p); /* * XXX - Several operations have the side effect * of vrele'ing their vp's. We must account for * that. (This should go away in the future.) */ if (reles & VDESC_VP0_WILLRELE) VREF(*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 & VDESC_VP0_WILLUNLOCK) LAYERFS_UPPERUNLOCK(*(vps_p[i]), 0, error1); if (reles & VDESC_VP0_WILLRELE) vrele(*(vps_p[i])); } } /* * Map the possible out-going vpp * (Assumes that the lower layer always returns * a VREF'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 vrele 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); /* * Only vop_lookup, vop_create, vop_makedir, vop_bmap, * vop_mknod, and vop_symlink return vpp's. The latter * two are VPP_WILLRELE, so we won't get here, and vop_bmap * doesn't call bypass as the lower vpp is fine (we're just * going to do i/o on it). vop_loookup doesn't call bypass * as a lookup on "." would generate a locking error. * So all the calls which get us here have a locked vpp. :-) */ error = layer_node_create(old_vps[0]->v_mount, **vppp, *vppp); } out: return (error); } /* * We have to carry on the locking protocol on the layer vnodes * as we progress through the tree. We also have to enforce read-only * if this layer is mounted read-only. */ int layer_lookup(v) void *v; { struct vop_lookup_args /* { struct vnodeop_desc *a_desc; struct vnode * a_dvp; struct vnode ** a_vpp; struct componentname * a_cnp; } */ *ap = v; struct componentname *cnp = ap->a_cnp; int flags = cnp->cn_flags; struct vnode *dvp, *vp, *ldvp; int error, r; dvp = ap->a_dvp; if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) return (EROFS); ldvp = LAYERVPTOLOWERVP(dvp); ap->a_dvp = ldvp; error = VCALL(ldvp, ap->a_desc->vdesc_offset, ap); vp = *ap->a_vpp; if (error == EJUSTRETURN && (flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && (cnp->cn_nameiop == CREATE || cnp->cn_nameiop == RENAME)) error = EROFS; /* * We must do the same locking and unlocking at this layer as * is done in the layers below us. It used to be we would try * to guess based on what was set with the flags and error codes. * * But that doesn't work. So now we have the underlying VOP_LOOKUP * tell us if it released the parent vnode, and we adjust the * upper node accordingly. We can't just look at the lock states * of the lower nodes as someone else might have come along and * locked the parent node after our call to VOP_LOOKUP locked it. */ if ((cnp->cn_flags & PDIRUNLOCK)) { LAYERFS_UPPERUNLOCK(dvp, 0, r); } if (ldvp == vp) { /* * Did lookup on "." or ".." in the root node of a mount point. * So we return dvp after a VREF. */ *ap->a_vpp = dvp; VREF(dvp); vrele(vp); } else if (vp != NULL) { error = layer_node_create(dvp->v_mount, vp, ap->a_vpp); } return (error); } /* * Setattr call. Disallow write attempts if the layer is mounted read-only. */ int layer_setattr(v) void *v; { struct vop_setattr_args /* { struct vnodeop_desc *a_desc; struct vnode *a_vp; struct vattr *a_vap; struct ucred *a_cred; struct proc *a_p; } */ *ap = v; struct vnode *vp = ap->a_vp; struct vattr *vap = ap->a_vap; if ((vap->va_flags != VNOVAL || vap->va_uid != (uid_t)VNOVAL || vap->va_gid != (gid_t)VNOVAL || vap->va_atime.tv_sec != VNOVAL || vap->va_mtime.tv_sec != VNOVAL || vap->va_mode != (mode_t)VNOVAL) && (vp->v_mount->mnt_flag & MNT_RDONLY)) return (EROFS); if (vap->va_size != VNOVAL) { switch (vp->v_type) { case VDIR: return (EISDIR); case VCHR: case VBLK: case VSOCK: case VFIFO: return (0); case VREG: case VLNK: default: /* * Disallow write attempts if the filesystem is * mounted read-only. */ if (vp->v_mount->mnt_flag & MNT_RDONLY) return (EROFS); } } return (LAYERFS_DO_BYPASS(vp, ap)); } /* * We handle getattr only to change the fsid. */ int layer_getattr(v) void *v; { struct vop_getattr_args /* { struct vnode *a_vp; struct vattr *a_vap; struct ucred *a_cred; struct proc *a_p; } */ *ap = v; struct vnode *vp = ap->a_vp; int error; if ((error = LAYERFS_DO_BYPASS(vp, ap)) != 0) return (error); /* Requires that arguments be restored. */ ap->a_vap->va_fsid = vp->v_mount->mnt_stat.f_fsid.val[0]; return (0); } int layer_access(v) void *v; { struct vop_access_args /* { struct vnode *a_vp; int a_mode; struct ucred *a_cred; struct proc *a_p; } */ *ap = v; struct vnode *vp = ap->a_vp; mode_t mode = ap->a_mode; /* * Disallow write attempts on read-only layers; * unless the file is a socket, fifo, or a block or * character device resident on the file system. */ if (mode & VWRITE) { switch (vp->v_type) { case VDIR: case VLNK: case VREG: if (vp->v_mount->mnt_flag & MNT_RDONLY) return (EROFS); break; default: break; } } return (LAYERFS_DO_BYPASS(vp, ap)); } /* * We must handle open to be able to catch MNT_NODEV and friends. */ int layer_open(v) void *v; { struct vop_open_args *ap = v; struct vnode *vp = ap->a_vp; enum vtype lower_type = LAYERVPTOLOWERVP(vp)->v_type; if (((lower_type == VBLK) || (lower_type == VCHR)) && (vp->v_mount->mnt_flag & MNT_NODEV)) return ENXIO; return LAYERFS_DO_BYPASS(vp, ap); } /* * We need to process our own vnode lock and then clear the * interlock flag as it applies only to our vnode, not the * vnodes below us on the stack. */ int layer_lock(v) void *v; { struct vop_lock_args /* { struct vnode *a_vp; int a_flags; struct proc *a_p; } */ *ap = v; struct vnode *vp = ap->a_vp, *lowervp; int flags = ap->a_flags, error; if (vp->v_vnlock != NULL) { /* * The lower level has exported a struct lock to us. Use * it so that all vnodes in the stack lock and unlock * simultaneously. Note: we don't DRAIN the lock as DRAIN * decommissions the lock - just because our vnode is * going away doesn't mean the struct lock below us is. * LK_EXCLUSIVE is fine. */ if ((flags & LK_TYPE_MASK) == LK_DRAIN) { return(lockmgr(vp->v_vnlock, (flags & ~LK_TYPE_MASK) | LK_EXCLUSIVE, &vp->v_interlock)); } else return(lockmgr(vp->v_vnlock, flags, &vp->v_interlock)); } else { /* * Ahh well. It would be nice if the fs we're over would * export a struct lock for us to use, but it doesn't. * * To prevent race conditions involving doing a lookup * on "..", we have to lock the lower node, then lock our * node. Most of the time it won't matter that we lock our * node (as any locking would need the lower one locked * first). But we can LK_DRAIN the upper lock as a step * towards decomissioning it. */ lowervp = LAYERVPTOLOWERVP(vp); if (flags & LK_INTERLOCK) { simple_unlock(&vp->v_interlock); flags &= ~LK_INTERLOCK; } if ((flags & LK_TYPE_MASK) == LK_DRAIN) { error = VOP_LOCK(lowervp, (flags & ~LK_TYPE_MASK) | LK_EXCLUSIVE); } else error = VOP_LOCK(lowervp, flags); if (error) return (error); if ((error = lockmgr(&vp->v_lock, flags, &vp->v_interlock))) { VOP_UNLOCK(lowervp, 0); } return (error); } } /* */ int layer_unlock(v) void *v; { struct vop_unlock_args /* { struct vnode *a_vp; int a_flags; struct proc *a_p; } */ *ap = v; struct vnode *vp = ap->a_vp; int flags = ap->a_flags; if (vp->v_vnlock != NULL) { return (lockmgr(vp->v_vnlock, ap->a_flags | LK_RELEASE, &vp->v_interlock)); } else { if (flags & LK_INTERLOCK) { simple_unlock(&vp->v_interlock); flags &= ~LK_INTERLOCK; } VOP_UNLOCK(LAYERVPTOLOWERVP(vp), flags); return (lockmgr(&vp->v_lock, ap->a_flags | LK_RELEASE, &vp->v_interlock)); } } /* * As long as genfs_nolock is in use, don't call VOP_ISLOCKED(lowervp) * if vp->v_vnlock == NULL as genfs_noislocked will always report 0. */ int layer_islocked(v) void *v; { struct vop_islocked_args /* { struct vnode *a_vp; } */ *ap = v; struct vnode *vp = ap->a_vp; if (vp->v_vnlock != NULL) return (lockstatus(vp->v_vnlock)); else return (lockstatus(&vp->v_lock)); } /* * If vinvalbuf is calling us, it's a "shallow fsync" -- don't bother * syncing the underlying vnodes, since they'll be fsync'ed when * reclaimed; otherwise, * pass it through to the underlying layer. * * XXX Do we still need to worry about shallow fsync? */ int layer_fsync(v) void *v; { struct vop_fsync_args /* { struct vnode *a_vp; struct ucred *a_cred; int a_flags; struct proc *a_p; } */ *ap = v; if (ap->a_flags & FSYNC_RECLAIM) { return 0; } return (LAYERFS_DO_BYPASS(ap->a_vp, ap)); } int layer_inactive(v) void *v; { struct vop_inactive_args /* { struct vnode *a_vp; struct proc *a_p; } */ *ap = v; /* * Do nothing (and _don't_ bypass). * Wait to vrele lowervp until reclaim, * so that until then our layer_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. */ VOP_UNLOCK(ap->a_vp, 0); return (0); } int layer_reclaim(v) void *v; { struct vop_reclaim_args /* { struct vnode *a_vp; struct proc *a_p; } */ *ap = v; struct vnode *vp = ap->a_vp; struct layer_mount *lmp = MOUNTTOLAYERMOUNT(vp->v_mount); struct layer_node *xp = VTOLAYER(vp); struct vnode *lowervp = xp->layer_lowervp; /* * Note: in vop_reclaim, the node's struct lock has been * decomissioned, so we have to be careful about calling * VOP's on ourself. Even if we turned a LK_DRAIN into an * LK_EXCLUSIVE in layer_lock, we still must be careful as VXLOCK is * set. */ /* After this assignment, this node will not be re-used. */ if ((vp == lmp->layerm_rootvp)) { /* * Oops! We no longer have a root node. Most likely reason is * that someone forcably unmunted the underlying fs. * * Now getting the root vnode will fail. We're dead. :-( */ lmp->layerm_rootvp = NULL; } xp->layer_lowervp = NULL; simple_lock(&lmp->layerm_hashlock); LIST_REMOVE(xp, layer_hash); simple_unlock(&lmp->layerm_hashlock); FREE(vp->v_data, M_TEMP); vp->v_data = NULL; vrele (lowervp); return (0); } /* * We just feed the returned vnode up to the caller - there's no need * to build a layer node on top of the node on which we're going to do * i/o. :-) */ int layer_bmap(v) void *v; { struct vop_bmap_args /* { struct vnode *a_vp; daddr_t a_bn; struct vnode **a_vpp; daddr_t *a_bnp; int *a_runp; } */ *ap = v; struct vnode *vp; ap->a_vp = vp = LAYERVPTOLOWERVP(ap->a_vp); return (VCALL(vp, ap->a_desc->vdesc_offset, ap)); } int layer_print(v) void *v; { struct vop_print_args /* { struct vnode *a_vp; } */ *ap = v; struct vnode *vp = ap->a_vp; printf ("\ttag VT_LAYERFS, vp=%p, lowervp=%p\n", vp, LAYERVPTOLOWERVP(vp)); return (0); } /* * XXX - vop_strategy must be hand coded because it has no * vnode in its arguments. * This goes away with a merged VM/buffer cache. */ int layer_strategy(v) void *v; { struct vop_strategy_args /* { struct buf *a_bp; } */ *ap = v; struct buf *bp = ap->a_bp; int error; struct vnode *savedvp; savedvp = bp->b_vp; bp->b_vp = LAYERVPTOLOWERVP(bp->b_vp); error = VOP_STRATEGY(bp); bp->b_vp = savedvp; return (error); } /* * XXX - like vop_strategy, vop_bwrite must be hand coded because it has no * vnode in its arguments. * This goes away with a merged VM/buffer cache. */ int layer_bwrite(v) void *v; { struct vop_bwrite_args /* { struct buf *a_bp; } */ *ap = v; struct buf *bp = ap->a_bp; int error; struct vnode *savedvp; savedvp = bp->b_vp; bp->b_vp = LAYERVPTOLOWERVP(bp->b_vp); error = VOP_BWRITE(bp); bp->b_vp = savedvp; return (error); }