/* $NetBSD: layer_vnops.c,v 1.72 2021/10/20 03:08:18 thorpej Exp $ */ /* * Copyright (c) 1999 National Aeronautics & Space Administration * All rights reserved. * * This software was written by William Studenmund of the * Numerical Aerospace Simulation 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. 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: lofs_vnops.c,v 1.11 1992/05/30 10:05:43 jsp Exp jsp * ...and... * @(#)null_vnodeops.c 1.20 92/07/07 UCLA Ficus project */ /* * Generic layer vnode operations. * * The layer.h, layer_extern.h, layer_vfs.c, and layer_vnops.c files provide * the core implementation of stacked file-systems. * * The layerfs 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 technique, and it is "layerfs-nodes" stack above all * lower-layer vnodes, not just over directory vnodes. * * OPERATION OF LAYERFS * * The layerfs is the minimum file system layer, bypassing all possible * operations to the lower layer for processing there. The majority of its * activity centers on the bypass routine, through which nearly all vnode * operations pass. * * The bypass routine accepts arbitrary vnode operations for handling by * the lower layer. It begins by examining vnode operation arguments and * replacing any layered nodes by their lower-layer equivalents. It then * invokes an operation on the lower layer. Finally, it replaces the * layered nodes in the arguments and, if a vnode is returned 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 layerfs. For instance, * layer_getattr() must change the fsid being returned. While layer_lock() * and layer_unlock() must handle any locking for the current vnode as well * as pass the lock request down. layer_inactive() and layer_reclaim() are * not bypassed so that they can handle freeing layerfs-specific data. Also, * certain vnode operations (create, mknod, remove, link, rename, mkdir, * rmdir, and symlink) change the locking state within the operation. 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 "layerfs-nodes" stack and lower layer, in effect * stacking two VFSes. The initial mount creates a single vnode stack for * the root of the new layerfs. All other vnode stacks are created as a * result of vnode operations on this or other layerfs vnode stacks. * * New vnode stacks come into existence as a result of an operation which * returns a vnode. The bypass routine stacks a layerfs-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 layerfs-node, * which was created when the null layer was mounted). Now consider opening * "sys". A layer_lookup() would be performed on the root layerfs-node. * This operation would bypass through to the lower layer which would return * a vnode representing the UFS "sys". Then, layer_bypass() builds a * layerfs-node aliasing the UFS "sys" and returns this to the caller. * Later operations on the layerfs-node "sys" will repeat this process when * constructing other vnode stacks. * * 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 any 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 handled on the lower layer. It has the advantage that the bypass * routine already must do argument mapping. An example of this is * layer_getattr(). * * A second approach is to directly invoke 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 vnode's arguments must be manually mapped. */ #include <sys/cdefs.h> __KERNEL_RCSID(0, "$NetBSD: layer_vnops.c,v 1.72 2021/10/20 03:08:18 thorpej Exp $"); #include <sys/param.h> #include <sys/systm.h> #include <sys/proc.h> #include <sys/time.h> #include <sys/vnode.h> #include <sys/mount.h> #include <sys/namei.h> #include <sys/kmem.h> #include <sys/buf.h> #include <sys/kauth.h> #include <sys/fcntl.h> #include <sys/fstrans.h> #include <miscfs/genfs/layer.h> #include <miscfs/genfs/layer_extern.h> #include <miscfs/genfs/genfs.h> #include <miscfs/specfs/specdev.h> /* * 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. * 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. * * 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(void *v) { struct vop_generic_args /* { struct vnodeop_desc *a_desc; <other random data follows, presumably> } */ *ap = v; int (**our_vnodeop_p)(void *); struct vnode **this_vp_p; int error; struct vnode *old_vps[VDESC_MAX_VPS], *vp0; struct vnode **vps_p[VDESC_MAX_VPS]; struct vnode ***vppp; struct mount *mp; struct vnodeop_desc *descp = ap->a_desc; int reles, i, flags; #ifdef DIAGNOSTIC /* * We require at least one vp. */ if (descp->vdesc_vp_offsets == NULL || descp->vdesc_vp_offsets[0] == VDESC_NO_OFFSET) panic("%s: no vp's in map.\n", __func__); #endif vps_p[0] = VOPARG_OFFSETTO(struct vnode**, descp->vdesc_vp_offsets[0], ap); vp0 = *vps_p[0]; mp = vp0->v_mount; flags = MOUNTTOLAYERMOUNT(mp)->layerm_flags; our_vnodeop_p = vp0->v_op; if (flags & LAYERFS_MBYPASSDEBUG) printf("%s: %s\n", __func__, 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_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 && !error) { vppp = VOPARG_OFFSETTO(struct vnode***, descp->vdesc_vpp_offset, ap); /* * Only vop_lookup, vop_create, vop_makedir, vop_mknod * and vop_symlink return vpp's. vop_lookup doesn't call bypass * as a lookup on "." would generate a locking error. * So all the calls which get us here have a unlocked vpp. :-) */ error = layer_node_create(mp, **vppp, *vppp); if (error) { vrele(**vppp); **vppp = NULL; } } 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(void *v) { struct vop_lookup_v2_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; struct vnode *dvp, *lvp, *ldvp; int error, flags = cnp->cn_flags; dvp = ap->a_dvp; if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { *ap->a_vpp = NULL; return EROFS; } ldvp = LAYERVPTOLOWERVP(dvp); ap->a_dvp = ldvp; error = VCALL(ldvp, ap->a_desc->vdesc_offset, ap); lvp = *ap->a_vpp; *ap->a_vpp = NULL; 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. */ if (ldvp == lvp) { /* * Got the same object back, because we looked up ".", * or ".." in the root node of a mount point. * So we make another reference to dvp and return it. */ vref(dvp); *ap->a_vpp = dvp; vrele(lvp); } else if (lvp != NULL) { /* Note: dvp and ldvp are both locked. */ KASSERT(error != ENOLCK); error = layer_node_create(dvp->v_mount, lvp, ap->a_vpp); if (error) { vrele(lvp); } } return error; } /* * Setattr call. Disallow write attempts if the layer is mounted read-only. */ int layer_setattr(void *v) { struct vop_setattr_args /* { struct vnodeop_desc *a_desc; struct vnode *a_vp; struct vattr *a_vap; kauth_cred_t a_cred; struct lwp *a_l; } */ *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(void *v) { struct vop_getattr_args /* { struct vnode *a_vp; struct vattr *a_vap; kauth_cred_t a_cred; struct lwp *a_l; } */ *ap = v; struct vnode *vp = ap->a_vp; int error; error = LAYERFS_DO_BYPASS(vp, ap); if (error) { return error; } /* Requires that arguments be restored. */ ap->a_vap->va_fsid = vp->v_mount->mnt_stat.f_fsidx.__fsid_val[0]; return 0; } int layer_access(void *v) { struct vop_access_args /* { struct vnode *a_vp; accmode_t a_accmode; kauth_cred_t a_cred; struct lwp *a_l; } */ *ap = v; struct vnode *vp = ap->a_vp; accmode_t accmode = ap->a_accmode; /* * 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 (accmode & 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 * and increment the lower v_writecount. */ int layer_open(void *v) { struct vop_open_args /* { const struct vnodeop_desc *a_desc; struct vnode *a_vp; int a_mode; kauth_cred_t a_cred; } */ *ap = v; struct vnode *vp = ap->a_vp; struct vnode *lvp = LAYERVPTOLOWERVP(vp); int error; if (((lvp->v_type == VBLK) || (lvp->v_type == VCHR)) && (vp->v_mount->mnt_flag & MNT_NODEV)) return ENXIO; error = LAYERFS_DO_BYPASS(vp, ap); if (error == 0 && (ap->a_mode & FWRITE)) { mutex_enter(lvp->v_interlock); lvp->v_writecount++; mutex_exit(lvp->v_interlock); } return error; } /* * We must handle close to decrement the lower v_writecount. */ int layer_close(void *v) { struct vop_close_args /* { const struct vnodeop_desc *a_desc; struct vnode *a_vp; int a_fflag; kauth_cred_t a_cred; } */ *ap = v; struct vnode *vp = ap->a_vp; struct vnode *lvp = LAYERVPTOLOWERVP(vp); if ((ap->a_fflag & FWRITE)) { mutex_enter(lvp->v_interlock); KASSERT(lvp->v_writecount > 0); lvp->v_writecount--; mutex_exit(lvp->v_interlock); } return LAYERFS_DO_BYPASS(vp, ap); } /* * 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(void *v) { struct vop_fsync_args /* { struct vnode *a_vp; kauth_cred_t a_cred; int a_flags; off_t offlo; off_t offhi; struct lwp *a_l; } */ *ap = v; int error; if (ap->a_flags & FSYNC_RECLAIM) { return 0; } if (ap->a_vp->v_type == VBLK || ap->a_vp->v_type == VCHR) { error = spec_fsync(v); if (error) return error; } return LAYERFS_DO_BYPASS(ap->a_vp, ap); } int layer_inactive(void *v) { struct vop_inactive_v2_args /* { struct vnode *a_vp; bool *a_recycle; } */ *ap = v; struct vnode *vp = ap->a_vp; /* * If we did a remove, don't cache the node. */ *ap->a_recycle = ((VTOLAYER(vp)->layer_flags & LAYERFS_REMOVED) != 0); /* * 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. */ return 0; } int layer_remove(void *v) { struct vop_remove_v3_args /* { struct vnode *a_dvp; struct vnode *a_vp; struct componentname *a_cnp; nlink_t ctx_vp_new_nlink; } */ *ap = v; struct vnode *vp = ap->a_vp; int error; vref(vp); error = LAYERFS_DO_BYPASS(vp, ap); if (error == 0) { VTOLAYER(vp)->layer_flags |= LAYERFS_REMOVED; } vrele(vp); return error; } int layer_rename(void *v) { struct vop_rename_args /* { struct vnode *a_fdvp; struct vnode *a_fvp; struct componentname *a_fcnp; struct vnode *a_tdvp; struct vnode *a_tvp; struct componentname *a_tcnp; } */ *ap = v; struct vnode *fdvp = ap->a_fdvp, *tvp; int error; tvp = ap->a_tvp; if (tvp) { if (tvp->v_mount != fdvp->v_mount) tvp = NULL; else vref(tvp); } error = LAYERFS_DO_BYPASS(fdvp, ap); if (tvp) { if (error == 0) VTOLAYER(tvp)->layer_flags |= LAYERFS_REMOVED; vrele(tvp); } return error; } int layer_rmdir(void *v) { struct vop_rmdir_v2_args /* { struct vnode *a_dvp; struct vnode *a_vp; struct componentname *a_cnp; } */ *ap = v; int error; struct vnode *vp = ap->a_vp; vref(vp); error = LAYERFS_DO_BYPASS(vp, ap); if (error == 0) { VTOLAYER(vp)->layer_flags |= LAYERFS_REMOVED; } vrele(vp); return error; } int layer_revoke(void *v) { struct vop_revoke_args /* { struct vnode *a_vp; int a_flags; } */ *ap = v; struct vnode *vp = ap->a_vp; struct vnode *lvp = LAYERVPTOLOWERVP(vp); int error; /* * We will most likely end up in vclean which uses the usecount * to determine if a vnode is active. Take an extra reference on * the lower vnode so it will always close and inactivate. */ vref(lvp); error = LAYERFS_DO_BYPASS(vp, ap); vrele(lvp); return error; } int layer_reclaim(void *v) { struct vop_reclaim_v2_args /* { struct vnode *a_vp; struct lwp *a_l; } */ *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; VOP_UNLOCK(vp); /* * Note: in vop_reclaim, the node's struct lock has been * decomissioned, so we have to be careful about calling * VOP's on ourself. We must be careful as VXLOCK is set. */ 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; } mutex_enter(vp->v_interlock); KASSERT(vp->v_interlock == lowervp->v_interlock); lowervp->v_writecount -= vp->v_writecount; mutex_exit(vp->v_interlock); /* After this assignment, this node will not be re-used. */ xp->layer_lowervp = NULL; kmem_free(vp->v_data, lmp->layerm_size); 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(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; vp = LAYERVPTOLOWERVP(ap->a_vp); ap->a_vp = vp; return VCALL(vp, ap->a_desc->vdesc_offset, ap); } int layer_print(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; } int layer_getpages(void *v) { struct vop_getpages_args /* { struct vnode *a_vp; voff_t a_offset; struct vm_page **a_m; int *a_count; int a_centeridx; vm_prot_t a_access_type; int a_advice; int a_flags; } */ *ap = v; struct vnode *vp = ap->a_vp; struct mount *mp = vp->v_mount; int error; krw_t op; KASSERT(rw_lock_held(vp->v_uobj.vmobjlock)); if (ap->a_flags & PGO_LOCKED) { return EBUSY; } ap->a_vp = LAYERVPTOLOWERVP(vp); KASSERT(vp->v_uobj.vmobjlock == ap->a_vp->v_uobj.vmobjlock); /* Just pass the request on to the underlying layer. */ op = rw_lock_op(vp->v_uobj.vmobjlock); rw_exit(vp->v_uobj.vmobjlock); fstrans_start(mp); rw_enter(vp->v_uobj.vmobjlock, op); if (mp == vp->v_mount) { /* Will release the lock. */ error = VCALL(ap->a_vp, VOFFSET(vop_getpages), ap); } else { rw_exit(vp->v_uobj.vmobjlock); error = ENOENT; } fstrans_done(mp); return error; } int layer_putpages(void *v) { struct vop_putpages_args /* { struct vnode *a_vp; voff_t a_offlo; voff_t a_offhi; int a_flags; } */ *ap = v; struct vnode *vp = ap->a_vp; KASSERT(rw_write_held(vp->v_uobj.vmobjlock)); ap->a_vp = LAYERVPTOLOWERVP(vp); KASSERT(vp->v_uobj.vmobjlock == ap->a_vp->v_uobj.vmobjlock); if (ap->a_flags & PGO_RECLAIM) { rw_exit(vp->v_uobj.vmobjlock); return 0; } /* Just pass the request on to the underlying layer. */ return VCALL(ap->a_vp, VOFFSET(vop_putpages), ap); }
