diff --git a/sys/fs/nullfs/null_vnops.c b/sys/fs/nullfs/null_vnops.c index 7db7a352f176..5daa302bedd1 100644 --- a/sys/fs/nullfs/null_vnops.c +++ b/sys/fs/nullfs/null_vnops.c @@ -1,1185 +1,1186 @@ /*- * SPDX-License-Identifier: BSD-3-Clause * * 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 * ...and... * @(#)null_vnodeops.c 1.20 92/07/07 UCLA Ficus project */ /* * Null Layer * * (See mount_nullfs(8) for more information.) * * The null layer duplicates a portion of the filesystem * name space under a new name. In this respect, it is * similar to the loopback filesystem. It differs from * the loopback fs in two respects: it is implemented using * a stackable layers techniques, and its "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 filesystem 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 filesystem 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_nullfs(8). * Mount_nullfs(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 filesystem layer, * simply 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 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, 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 existence 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_nullfs /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". 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 filesystem 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 a 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 null_getattrs in the null layer. * * 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 arguments must be manualy mapped. * */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include static int null_bug_bypass = 0; /* for debugging: enables bypass printf'ing */ SYSCTL_INT(_debug, OID_AUTO, nullfs_bug_bypass, CTLFLAG_RW, &null_bug_bypass, 0, ""); /* * 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. * * 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 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. * * 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 null_bypass(struct vop_generic_args *ap) { struct vnode **this_vp_p; struct vnode *old_vps[VDESC_MAX_VPS]; struct vnode **vps_p[VDESC_MAX_VPS]; struct vnode ***vppp; struct vnode *lvp; struct vnodeop_desc *descp = ap->a_desc; int error, i, reles; if (null_bug_bypass) printf ("null_bypass: %s\n", descp->vdesc_name); #ifdef DIAGNOSTIC /* * 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"); #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 != 0 && (*this_vp_p == NULLVP || (*this_vp_p)->v_op != &null_vnodeops)) { old_vps[i] = NULLVP; } else { old_vps[i] = *this_vp_p; *(vps_p[i]) = NULLVPTOLOWERVP(*this_vp_p); /* * The upper vnode reference to the lower * vnode is the only reference that keeps our * pointer to the lower vnode alive. If lower * vnode is relocked during the VOP call, * upper vnode might become unlocked and * reclaimed, which invalidates our reference. * Add a transient hold around VOP call. */ vhold(*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. */ if (vps_p[0] != NULL && *vps_p[0] != NULL) { error = VCALL(ap); } else { printf("null_bypass: no map for %s\n", descp->vdesc_name); error = EINVAL; } /* * 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] != NULL) { lvp = *(vps_p[i]); /* * Get rid of the transient hold on lvp. * If lowervp was unlocked during VOP * operation, nullfs upper vnode could have * been reclaimed, which changes its v_vnlock * back to private v_lock. In this case we * must move lock ownership from lower to * upper (reclaimed) vnode. */ if (lvp != NULLVP) { if (VOP_ISLOCKED(lvp) == LK_EXCLUSIVE && old_vps[i]->v_vnlock != lvp->v_vnlock) { VOP_UNLOCK(lvp); VOP_LOCK(old_vps[i], LK_EXCLUSIVE | LK_RETRY); } vdrop(lvp); } *(vps_p[i]) = old_vps[i]; #if 0 if (reles & VDESC_VP0_WILLUNLOCK) VOP_UNLOCK(*(vps_p[i]), 0); #endif 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 == 0) { /* * 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.) */ vppp = VOPARG_OFFSETTO(struct vnode ***, descp->vdesc_vpp_offset, ap); if (*vppp != NULL) error = null_nodeget(old_vps[0]->v_mount, **vppp, *vppp); } return (error); } static int null_add_writecount(struct vop_add_writecount_args *ap) { struct vnode *lvp, *vp; int error; vp = ap->a_vp; lvp = NULLVPTOLOWERVP(vp); VI_LOCK(vp); /* text refs are bypassed to lowervp */ VNASSERT(vp->v_writecount >= 0, vp, ("wrong null writecount")); VNASSERT(vp->v_writecount + ap->a_inc >= 0, vp, ("wrong writecount inc %d", ap->a_inc)); error = VOP_ADD_WRITECOUNT(lvp, ap->a_inc); if (error == 0) vp->v_writecount += ap->a_inc; VI_UNLOCK(vp); 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. */ static int null_lookup(struct vop_lookup_args *ap) { struct componentname *cnp = ap->a_cnp; struct vnode *dvp = ap->a_dvp; int flags = cnp->cn_flags; struct vnode *vp, *ldvp, *lvp; struct mount *mp; int error; mp = dvp->v_mount; if ((flags & ISLASTCN) != 0 && (mp->mnt_flag & MNT_RDONLY) != 0 && (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) return (EROFS); /* * Although it is possible to call null_bypass(), we'll do * a direct call to reduce overhead */ ldvp = NULLVPTOLOWERVP(dvp); vp = lvp = NULL; /* * Renames in the lower mounts might create an inconsistent * configuration where lower vnode is moved out of the * directory tree remounted by our null mount. Do not try to * handle it fancy, just avoid VOP_LOOKUP() with DOTDOT name * which cannot be handled by VOP, at least passing over lower * root. */ if ((ldvp->v_vflag & VV_ROOT) != 0 && (flags & ISDOTDOT) != 0) { KASSERT((dvp->v_vflag & VV_ROOT) == 0, ("ldvp %p fl %#x dvp %p fl %#x flags %#x", ldvp, ldvp->v_vflag, dvp, dvp->v_vflag, flags)); return (ENOENT); } /* * Hold ldvp. The reference on it, owned by dvp, is lost in * case of dvp reclamation, and we need ldvp to move our lock * from ldvp to dvp. */ vhold(ldvp); error = VOP_LOOKUP(ldvp, &lvp, cnp); /* * VOP_LOOKUP() on lower vnode may unlock ldvp, which allows * dvp to be reclaimed due to shared v_vnlock. Check for the * doomed state and return error. */ if (VN_IS_DOOMED(dvp)) { if (error == 0 || error == EJUSTRETURN) { if (lvp != NULL) vput(lvp); error = ENOENT; } /* * If vgone() did reclaimed dvp before curthread * relocked ldvp, the locks of dvp and ldpv are no * longer shared. In this case, relock of ldvp in * lower fs VOP_LOOKUP() does not restore the locking * state of dvp. Compensate for this by unlocking * ldvp and locking dvp, which is also correct if the * locks are still shared. */ VOP_UNLOCK(ldvp); vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY); } vdrop(ldvp); if (error == EJUSTRETURN && (flags & ISLASTCN) != 0 && (mp->mnt_flag & MNT_RDONLY) != 0 && (cnp->cn_nameiop == CREATE || cnp->cn_nameiop == RENAME)) error = EROFS; if ((error == 0 || error == EJUSTRETURN) && lvp != NULL) { if (ldvp == lvp) { *ap->a_vpp = dvp; VREF(dvp); vrele(lvp); } else { error = null_nodeget(mp, lvp, &vp); if (error == 0) *ap->a_vpp = vp; } } return (error); } static int null_open(struct vop_open_args *ap) { int retval; struct vnode *vp, *ldvp; vp = ap->a_vp; ldvp = NULLVPTOLOWERVP(vp); retval = null_bypass(&ap->a_gen); if (retval == 0) { vp->v_object = ldvp->v_object; if ((vn_irflag_read(ldvp) & VIRF_PGREAD) != 0) { MPASS(vp->v_object != NULL); if ((vn_irflag_read(vp) & VIRF_PGREAD) == 0) { vn_irflag_set_cond(vp, VIRF_PGREAD); } } } return (retval); } /* * Setattr call. Disallow write attempts if the layer is mounted read-only. */ static int null_setattr(struct vop_setattr_args *ap) { 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: if (vap->va_flags != VNOVAL) return (EOPNOTSUPP); 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 (null_bypass((struct vop_generic_args *)ap)); } /* * We handle stat and getattr only to change the fsid. */ static int null_stat(struct vop_stat_args *ap) { int error; if ((error = null_bypass((struct vop_generic_args *)ap)) != 0) return (error); ap->a_sb->st_dev = ap->a_vp->v_mount->mnt_stat.f_fsid.val[0]; return (0); } static int null_getattr(struct vop_getattr_args *ap) { int error; if ((error = null_bypass((struct vop_generic_args *)ap)) != 0) return (error); ap->a_vap->va_fsid = ap->a_vp->v_mount->mnt_stat.f_fsid.val[0]; return (0); } /* * Handle to disallow write access if mounted read-only. */ static int null_access(struct vop_access_args *ap) { 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 filesystem. */ 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 (null_bypass((struct vop_generic_args *)ap)); } static int null_accessx(struct vop_accessx_args *ap) { 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 filesystem. */ 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 (null_bypass((struct vop_generic_args *)ap)); } /* * Increasing refcount of lower vnode is needed at least for the case * when lower FS is NFS to do sillyrename if the file is in use. * Unfortunately v_usecount is incremented in many places in * the kernel and, as such, there may be races that result in * the NFS client doing an extraneous silly rename, but that seems * preferable to not doing a silly rename when it is needed. */ static int null_remove(struct vop_remove_args *ap) { int retval, vreleit; struct vnode *lvp, *vp; vp = ap->a_vp; if (vrefcnt(vp) > 1) { lvp = NULLVPTOLOWERVP(vp); VREF(lvp); vreleit = 1; } else vreleit = 0; VTONULL(vp)->null_flags |= NULLV_DROP; retval = null_bypass(&ap->a_gen); if (vreleit != 0) vrele(lvp); return (retval); } /* * We handle this to eliminate null FS to lower FS * file moving. Don't know why we don't allow this, * possibly we should. */ static int null_rename(struct vop_rename_args *ap) { struct vnode *fdvp, *fvp, *tdvp, *tvp; struct vnode *lfdvp, *lfvp, *ltdvp, *ltvp; struct null_node *fdnn, *fnn, *tdnn, *tnn; int error; tdvp = ap->a_tdvp; fvp = ap->a_fvp; fdvp = ap->a_fdvp; tvp = ap->a_tvp; lfdvp = NULL; /* Check for cross-device rename. */ if ((fvp->v_mount != tdvp->v_mount) || (tvp != NULL && fvp->v_mount != tvp->v_mount)) { error = EXDEV; goto upper_err; } VI_LOCK(fdvp); fdnn = VTONULL(fdvp); if (fdnn == NULL) { /* fdvp is not locked, can be doomed */ VI_UNLOCK(fdvp); error = ENOENT; goto upper_err; } lfdvp = fdnn->null_lowervp; vref(lfdvp); VI_UNLOCK(fdvp); VI_LOCK(fvp); fnn = VTONULL(fvp); if (fnn == NULL) { VI_UNLOCK(fvp); error = ENOENT; goto upper_err; } lfvp = fnn->null_lowervp; vref(lfvp); VI_UNLOCK(fvp); tdnn = VTONULL(tdvp); ltdvp = tdnn->null_lowervp; vref(ltdvp); if (tvp != NULL) { tnn = VTONULL(tvp); ltvp = tnn->null_lowervp; vref(ltvp); tnn->null_flags |= NULLV_DROP; } else { ltvp = NULL; } error = VOP_RENAME(lfdvp, lfvp, ap->a_fcnp, ltdvp, ltvp, ap->a_tcnp); vrele(fdvp); vrele(fvp); vrele(tdvp); if (tvp != NULL) vrele(tvp); return (error); upper_err: if (tdvp == tvp) vrele(tdvp); else vput(tdvp); if (tvp) vput(tvp); if (lfdvp != NULL) vrele(lfdvp); vrele(fdvp); vrele(fvp); return (error); } static int null_rmdir(struct vop_rmdir_args *ap) { VTONULL(ap->a_vp)->null_flags |= NULLV_DROP; return (null_bypass(&ap->a_gen)); } /* * 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. */ static int null_lock(struct vop_lock1_args *ap) { struct vnode *vp = ap->a_vp; int flags; struct null_node *nn; struct vnode *lvp; int error; if ((ap->a_flags & LK_INTERLOCK) == 0) VI_LOCK(vp); else ap->a_flags &= ~LK_INTERLOCK; flags = ap->a_flags; nn = VTONULL(vp); /* * If we're still active we must ask the lower layer to * lock as ffs has special lock considerations in its * vop lock. */ if (nn != NULL && (lvp = NULLVPTOLOWERVP(vp)) != NULL) { /* * We have to hold the vnode here to solve a potential * reclaim race. If we're forcibly vgone'd while we * still have refs, a thread could be sleeping inside * the lowervp's vop_lock routine. When we vgone we will * drop our last ref to the lowervp, which would allow it * to be reclaimed. The lowervp could then be recycled, * in which case it is not legal to be sleeping in its VOP. * We prevent it from being recycled by holding the vnode * here. */ vholdnz(lvp); VI_UNLOCK(vp); error = VOP_LOCK(lvp, flags); /* * We might have slept to get the lock and someone might have * clean our vnode already, switching vnode lock from one in * lowervp to v_lock in our own vnode structure. Handle this * case by reacquiring correct lock in requested mode. */ if (VTONULL(vp) == NULL && error == 0) { ap->a_flags &= ~LK_TYPE_MASK; switch (flags & LK_TYPE_MASK) { case LK_SHARED: ap->a_flags |= LK_SHARED; break; case LK_UPGRADE: case LK_EXCLUSIVE: ap->a_flags |= LK_EXCLUSIVE; break; default: panic("Unsupported lock request %d\n", ap->a_flags); } VOP_UNLOCK(lvp); error = vop_stdlock(ap); } vdrop(lvp); } else { VI_UNLOCK(vp); error = vop_stdlock(ap); } return (error); } /* * We need to process our own vnode unlock and then clear the * interlock flag as it applies only to our vnode, not the * vnodes below us on the stack. */ static int null_unlock(struct vop_unlock_args *ap) { struct vnode *vp = ap->a_vp; struct null_node *nn; struct vnode *lvp; int error; nn = VTONULL(vp); if (nn != NULL && (lvp = NULLVPTOLOWERVP(vp)) != NULL) { vholdnz(lvp); error = VOP_UNLOCK(lvp); vdrop(lvp); } else { error = vop_stdunlock(ap); } return (error); } /* * Do not allow the VOP_INACTIVE to be passed to the lower layer, * since the reference count on the lower vnode is not related to * ours. */ static int null_want_recycle(struct vnode *vp) { struct vnode *lvp; struct null_node *xp; struct mount *mp; struct null_mount *xmp; xp = VTONULL(vp); lvp = NULLVPTOLOWERVP(vp); mp = vp->v_mount; xmp = MOUNTTONULLMOUNT(mp); if ((xmp->nullm_flags & NULLM_CACHE) == 0 || (xp->null_flags & NULLV_DROP) != 0 || (lvp->v_vflag & VV_NOSYNC) != 0) { /* * If this is the last reference and caching of the * nullfs vnodes is not enabled, or the lower vnode is * deleted, then free up the vnode so as not to tie up * the lower vnodes. */ return (1); } return (0); } static int null_inactive(struct vop_inactive_args *ap) { struct vnode *vp; vp = ap->a_vp; if (null_want_recycle(vp)) { vp->v_object = NULL; vrecycle(vp); } return (0); } static int null_need_inactive(struct vop_need_inactive_args *ap) { return (null_want_recycle(ap->a_vp) || vn_need_pageq_flush(ap->a_vp)); } /* * Now, the nullfs vnode and, due to the sharing lock, the lower * vnode, are exclusively locked, and we shall destroy the null vnode. */ static int null_reclaim(struct vop_reclaim_args *ap) { struct vnode *vp; struct null_node *xp; struct vnode *lowervp; vp = ap->a_vp; xp = VTONULL(vp); lowervp = xp->null_lowervp; KASSERT(lowervp != NULL && vp->v_vnlock != &vp->v_lock, ("Reclaiming incomplete null vnode %p", vp)); null_hashrem(xp); /* * Use the interlock to protect the clearing of v_data to * prevent faults in null_lock(). */ lockmgr(&vp->v_lock, LK_EXCLUSIVE, NULL); VI_LOCK(vp); vp->v_data = NULL; vp->v_object = NULL; vp->v_vnlock = &vp->v_lock; /* * If we were opened for write, we leased the write reference * to the lower vnode. If this is a reclamation due to the * forced unmount, undo the reference now. */ if (vp->v_writecount > 0) VOP_ADD_WRITECOUNT(lowervp, -vp->v_writecount); else if (vp->v_writecount < 0) vp->v_writecount = 0; VI_UNLOCK(vp); if ((xp->null_flags & NULLV_NOUNLOCK) != 0) vunref(lowervp); else vput(lowervp); free(xp, M_NULLFSNODE); return (0); } static int null_print(struct vop_print_args *ap) { struct vnode *vp = ap->a_vp; printf("\tvp=%p, lowervp=%p\n", vp, VTONULL(vp)->null_lowervp); return (0); } /* ARGSUSED */ static int null_getwritemount(struct vop_getwritemount_args *ap) { struct null_node *xp; struct vnode *lowervp; struct vnode *vp; vp = ap->a_vp; VI_LOCK(vp); xp = VTONULL(vp); if (xp && (lowervp = xp->null_lowervp)) { vholdnz(lowervp); VI_UNLOCK(vp); VOP_GETWRITEMOUNT(lowervp, ap->a_mpp); vdrop(lowervp); } else { VI_UNLOCK(vp); *(ap->a_mpp) = NULL; } return (0); } static int null_vptofh(struct vop_vptofh_args *ap) { struct vnode *lvp; lvp = NULLVPTOLOWERVP(ap->a_vp); return VOP_VPTOFH(lvp, ap->a_fhp); } static int null_vptocnp(struct vop_vptocnp_args *ap) { struct vnode *vp = ap->a_vp; struct vnode **dvp = ap->a_vpp; struct vnode *lvp, *ldvp; struct mount *mp; int error, locked; locked = VOP_ISLOCKED(vp); lvp = NULLVPTOLOWERVP(vp); mp = vp->v_mount; error = vfs_busy(mp, MBF_NOWAIT); if (error != 0) return (error); vhold(lvp); VOP_UNLOCK(vp); /* vp is held by vn_vptocnp_locked that called us */ ldvp = lvp; vref(lvp); error = vn_vptocnp(&ldvp, ap->a_buf, ap->a_buflen); vdrop(lvp); if (error != 0) { vn_lock(vp, locked | LK_RETRY); vfs_unbusy(mp); return (ENOENT); } error = vn_lock(ldvp, LK_SHARED); if (error != 0) { vrele(ldvp); vn_lock(vp, locked | LK_RETRY); vfs_unbusy(mp); return (ENOENT); } error = null_nodeget(mp, ldvp, dvp); if (error == 0) { #ifdef DIAGNOSTIC NULLVPTOLOWERVP(*dvp); #endif VOP_UNLOCK(*dvp); /* keep reference on *dvp */ } vn_lock(vp, locked | LK_RETRY); vfs_unbusy(mp); return (error); } static int null_read_pgcache(struct vop_read_pgcache_args *ap) { struct vnode *lvp, *vp; struct null_node *xp; int error; vp = ap->a_vp; VI_LOCK(vp); xp = VTONULL(vp); if (xp == NULL) { VI_UNLOCK(vp); return (EJUSTRETURN); } lvp = xp->null_lowervp; vref(lvp); VI_UNLOCK(vp); error = VOP_READ_PGCACHE(lvp, ap->a_uio, ap->a_ioflag, ap->a_cred); vrele(lvp); return (error); } static int null_advlock(struct vop_advlock_args *ap) { struct vnode *lvp, *vp; struct null_node *xp; int error; vp = ap->a_vp; VI_LOCK(vp); xp = VTONULL(vp); if (xp == NULL) { VI_UNLOCK(vp); return (EBADF); } lvp = xp->null_lowervp; vref(lvp); VI_UNLOCK(vp); error = VOP_ADVLOCK(lvp, ap->a_id, ap->a_op, ap->a_fl, ap->a_flags); vrele(lvp); return (error); } /* * Avoid standard bypass, since lower dvp and vp could be no longer * valid after vput(). */ static int null_vput_pair(struct vop_vput_pair_args *ap) { struct mount *mp; struct vnode *dvp, *ldvp, *lvp, *vp, *vp1, **vpp; int error, res; dvp = ap->a_dvp; ldvp = NULLVPTOLOWERVP(dvp); vref(ldvp); vpp = ap->a_vpp; vp = NULL; lvp = NULL; mp = NULL; if (vpp != NULL) vp = *vpp; if (vp != NULL) { lvp = NULLVPTOLOWERVP(vp); vref(lvp); if (!ap->a_unlock_vp) { vhold(vp); vhold(lvp); mp = vp->v_mount; vfs_ref(mp); } } res = VOP_VPUT_PAIR(ldvp, lvp != NULL ? &lvp : NULL, true); if (vp != NULL && ap->a_unlock_vp) vrele(vp); vrele(dvp); if (vp == NULL || ap->a_unlock_vp) return (res); /* lvp has been unlocked and vp might be reclaimed */ VOP_LOCK(vp, LK_EXCLUSIVE | LK_RETRY); if (vp->v_data == NULL && vfs_busy(mp, MBF_NOWAIT) == 0) { vput(vp); vget(lvp, LK_EXCLUSIVE | LK_RETRY); if (VN_IS_DOOMED(lvp)) { vput(lvp); vget(vp, LK_EXCLUSIVE | LK_RETRY); } else { error = null_nodeget(mp, lvp, &vp1); if (error == 0) { *vpp = vp1; } else { vget(vp, LK_EXCLUSIVE | LK_RETRY); } } vfs_unbusy(mp); } vdrop(lvp); vdrop(vp); vfs_rel(mp); return (res); } static int null_getlowvnode(struct vop_getlowvnode_args *ap) { struct vnode *vp, *vpl; vp = ap->a_vp; if (vn_lock(vp, LK_SHARED) != 0) return (EBADF); vpl = NULLVPTOLOWERVP(vp); vhold(vpl); VOP_UNLOCK(vp); VOP_GETLOWVNODE(vpl, ap->a_vplp, ap->a_flags); vdrop(vpl); return (0); } /* * Global vfs data structures */ struct vop_vector null_vnodeops = { .vop_bypass = null_bypass, .vop_access = null_access, .vop_accessx = null_accessx, .vop_advlock = null_advlock, .vop_advlockpurge = vop_stdadvlockpurge, .vop_bmap = VOP_EOPNOTSUPP, .vop_stat = null_stat, .vop_getattr = null_getattr, .vop_getlowvnode = null_getlowvnode, .vop_getwritemount = null_getwritemount, .vop_inactive = null_inactive, .vop_need_inactive = null_need_inactive, .vop_islocked = vop_stdislocked, .vop_lock1 = null_lock, .vop_lookup = null_lookup, .vop_open = null_open, .vop_print = null_print, .vop_read_pgcache = null_read_pgcache, .vop_reclaim = null_reclaim, .vop_remove = null_remove, .vop_rename = null_rename, .vop_rmdir = null_rmdir, .vop_setattr = null_setattr, .vop_strategy = VOP_EOPNOTSUPP, .vop_unlock = null_unlock, .vop_vptocnp = null_vptocnp, .vop_vptofh = null_vptofh, .vop_add_writecount = null_add_writecount, .vop_vput_pair = null_vput_pair, + .vop_copy_file_range = VOP_PANIC, }; VFS_VOP_VECTOR_REGISTER(null_vnodeops);