/*- * SPDX-License-Identifier: BSD-3-Clause * * Copyright (c) 1994 Jan-Simon Pendry * Copyright (c) 1994 * The Regents of the University of California. All rights reserved. * Copyright (c) 2005, 2006, 2012 Masanori Ozawa , ONGS Inc. * Copyright (c) 2006, 2012 Daichi Goto * * This code is derived from software contributed to Berkeley by * Jan-Simon Pendry. * * 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. * * @(#)union_subr.c 8.20 (Berkeley) 5/20/95 */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define NUNIONFSNODECACHE 16 #define UNIONFSHASHMASK (NUNIONFSNODECACHE - 1) static MALLOC_DEFINE(M_UNIONFSHASH, "UNIONFS hash", "UNIONFS hash table"); MALLOC_DEFINE(M_UNIONFSNODE, "UNIONFS node", "UNIONFS vnode private part"); MALLOC_DEFINE(M_UNIONFSPATH, "UNIONFS path", "UNIONFS path private part"); static struct task unionfs_deferred_rele_task; static struct mtx unionfs_deferred_rele_lock; static STAILQ_HEAD(, unionfs_node) unionfs_deferred_rele_list = STAILQ_HEAD_INITIALIZER(unionfs_deferred_rele_list); static TASKQUEUE_DEFINE_THREAD(unionfs_rele); unsigned int unionfs_ndeferred = 0; SYSCTL_UINT(_vfs, OID_AUTO, unionfs_ndeferred, CTLFLAG_RD, &unionfs_ndeferred, 0, "unionfs deferred vnode release"); static void unionfs_deferred_rele(void *, int); /* * Initialize */ int unionfs_init(struct vfsconf *vfsp) { UNIONFSDEBUG("unionfs_init\n"); /* printed during system boot */ TASK_INIT(&unionfs_deferred_rele_task, 0, unionfs_deferred_rele, NULL); mtx_init(&unionfs_deferred_rele_lock, "uniondefr", NULL, MTX_DEF); return (0); } /* * Uninitialize */ int unionfs_uninit(struct vfsconf *vfsp) { taskqueue_quiesce(taskqueue_unionfs_rele); taskqueue_free(taskqueue_unionfs_rele); mtx_destroy(&unionfs_deferred_rele_lock); return (0); } static void unionfs_deferred_rele(void *arg __unused, int pending __unused) { STAILQ_HEAD(, unionfs_node) local_rele_list; struct unionfs_node *unp, *tunp; unsigned int ndeferred; ndeferred = 0; STAILQ_INIT(&local_rele_list); mtx_lock(&unionfs_deferred_rele_lock); STAILQ_CONCAT(&local_rele_list, &unionfs_deferred_rele_list); mtx_unlock(&unionfs_deferred_rele_lock); STAILQ_FOREACH_SAFE(unp, &local_rele_list, un_rele, tunp) { ++ndeferred; MPASS(unp->un_dvp != NULL); vrele(unp->un_dvp); free(unp, M_UNIONFSNODE); } /* We expect this function to be single-threaded, thus no atomic */ unionfs_ndeferred += ndeferred; } static struct unionfs_node_hashhead * unionfs_get_hashhead(struct vnode *dvp, struct vnode *lookup) { struct unionfs_node *unp; unp = VTOUNIONFS(dvp); return (&(unp->un_hashtbl[vfs_hash_index(lookup) & UNIONFSHASHMASK])); } /* * Attempt to lookup a cached unionfs vnode by upper/lower vp * from dvp, with dvp's interlock held. */ static struct vnode * unionfs_get_cached_vnode_locked(struct vnode *lookup, struct vnode *dvp) { struct unionfs_node *unp; struct unionfs_node_hashhead *hd; struct vnode *vp; hd = unionfs_get_hashhead(dvp, lookup); LIST_FOREACH(unp, hd, un_hash) { if (unp->un_uppervp == lookup || unp->un_lowervp == lookup) { vp = UNIONFSTOV(unp); VI_LOCK_FLAGS(vp, MTX_DUPOK); vp->v_iflag &= ~VI_OWEINACT; if (VN_IS_DOOMED(vp) || ((vp->v_iflag & VI_DOINGINACT) != 0)) { VI_UNLOCK(vp); vp = NULLVP; } else { vrefl(vp); VI_UNLOCK(vp); } return (vp); } } return (NULLVP); } /* * Get the cached vnode. */ static struct vnode * unionfs_get_cached_vnode(struct vnode *uvp, struct vnode *lvp, struct vnode *dvp) { struct vnode *vp; vp = NULLVP; VI_LOCK(dvp); if (uvp != NULLVP) vp = unionfs_get_cached_vnode_locked(uvp, dvp); else if (lvp != NULLVP) vp = unionfs_get_cached_vnode_locked(lvp, dvp); VI_UNLOCK(dvp); return (vp); } /* * Add the new vnode into cache. */ static struct vnode * unionfs_ins_cached_vnode(struct unionfs_node *uncp, struct vnode *dvp) { struct unionfs_node_hashhead *hd; struct vnode *vp; ASSERT_VOP_ELOCKED(uncp->un_uppervp, __func__); ASSERT_VOP_ELOCKED(uncp->un_lowervp, __func__); KASSERT(uncp->un_uppervp == NULLVP || uncp->un_uppervp->v_type == VDIR, ("%s: v_type != VDIR", __func__)); KASSERT(uncp->un_lowervp == NULLVP || uncp->un_lowervp->v_type == VDIR, ("%s: v_type != VDIR", __func__)); vp = NULLVP; VI_LOCK(dvp); if (uncp->un_uppervp != NULL) vp = unionfs_get_cached_vnode_locked(uncp->un_uppervp, dvp); else if (uncp->un_lowervp != NULL) vp = unionfs_get_cached_vnode_locked(uncp->un_lowervp, dvp); if (vp == NULLVP) { hd = unionfs_get_hashhead(dvp, (uncp->un_uppervp != NULLVP ? uncp->un_uppervp : uncp->un_lowervp)); LIST_INSERT_HEAD(hd, uncp, un_hash); } VI_UNLOCK(dvp); return (vp); } /* * Remove the vnode. */ static void unionfs_rem_cached_vnode(struct unionfs_node *unp, struct vnode *dvp) { KASSERT(unp != NULL, ("%s: null node", __func__)); KASSERT(dvp != NULLVP, ("%s: null parent vnode", __func__)); VI_LOCK(dvp); if (unp->un_hash.le_prev != NULL) { LIST_REMOVE(unp, un_hash); unp->un_hash.le_next = NULL; unp->un_hash.le_prev = NULL; } VI_UNLOCK(dvp); } /* * Common cleanup handling for unionfs_nodeget * Upper, lower, and parent directory vnodes are expected to be referenced by * the caller. Upper and lower vnodes, if non-NULL, are also expected to be * exclusively locked by the caller. * This function will return with the caller's locks and references undone. */ static void unionfs_nodeget_cleanup(struct vnode *vp, struct unionfs_node *unp) { /* * Lock and reset the default vnode lock; vgone() expects a locked * vnode, and we're going to reset the vnode ops. */ lockmgr(&vp->v_lock, LK_EXCLUSIVE, NULL); /* * Clear out private data and reset the vnode ops to avoid use of * unionfs vnode ops on a partially constructed vnode. */ VI_LOCK(vp); vp->v_data = NULL; vp->v_vnlock = &vp->v_lock; vp->v_op = &dead_vnodeops; VI_UNLOCK(vp); vgone(vp); vput(vp); if (unp->un_dvp != NULLVP) vrele(unp->un_dvp); if (unp->un_uppervp != NULLVP) vput(unp->un_uppervp); if (unp->un_lowervp != NULLVP) vput(unp->un_lowervp); if (unp->un_hashtbl != NULL) hashdestroy(unp->un_hashtbl, M_UNIONFSHASH, UNIONFSHASHMASK); free(unp->un_path, M_UNIONFSPATH); free(unp, M_UNIONFSNODE); } /* * Make a new or get existing unionfs node. * * uppervp and lowervp should be unlocked. Because if new unionfs vnode is * locked, uppervp or lowervp is locked too. In order to prevent dead lock, * you should not lock plurality simultaneously. */ int unionfs_nodeget(struct mount *mp, struct vnode *uppervp, struct vnode *lowervp, struct vnode *dvp, struct vnode **vpp, struct componentname *cnp) { char *path; struct unionfs_mount *ump; struct unionfs_node *unp; struct vnode *vp; u_long hashmask; int error; int lkflags; __enum_uint8(vtype) vt; error = 0; ump = MOUNTTOUNIONFSMOUNT(mp); lkflags = (cnp ? cnp->cn_lkflags : 0); path = (cnp ? cnp->cn_nameptr : NULL); *vpp = NULLVP; if (uppervp == NULLVP && lowervp == NULLVP) panic("%s: upper and lower is null", __func__); vt = (uppervp != NULLVP ? uppervp->v_type : lowervp->v_type); /* If it has no ISLASTCN flag, path check is skipped. */ if (cnp && !(cnp->cn_flags & ISLASTCN)) path = NULL; /* check the cache */ if (dvp != NULLVP && vt == VDIR) { vp = unionfs_get_cached_vnode(uppervp, lowervp, dvp); if (vp != NULLVP) { *vpp = vp; goto unionfs_nodeget_out; } } unp = malloc(sizeof(struct unionfs_node), M_UNIONFSNODE, M_WAITOK | M_ZERO); error = getnewvnode("unionfs", mp, &unionfs_vnodeops, &vp); if (error != 0) { free(unp, M_UNIONFSNODE); return (error); } if (dvp != NULLVP) vref(dvp); if (uppervp != NULLVP) vref(uppervp); if (lowervp != NULLVP) vref(lowervp); if (vt == VDIR) { unp->un_hashtbl = hashinit(NUNIONFSNODECACHE, M_UNIONFSHASH, &hashmask); KASSERT(hashmask == UNIONFSHASHMASK, ("unexpected unionfs hash mask 0x%lx", hashmask)); } unp->un_vnode = vp; unp->un_uppervp = uppervp; unp->un_lowervp = lowervp; unp->un_dvp = dvp; if (uppervp != NULLVP) vp->v_vnlock = uppervp->v_vnlock; else vp->v_vnlock = lowervp->v_vnlock; if (path != NULL) { unp->un_path = malloc(cnp->cn_namelen + 1, M_UNIONFSPATH, M_WAITOK | M_ZERO); bcopy(cnp->cn_nameptr, unp->un_path, cnp->cn_namelen); unp->un_path[cnp->cn_namelen] = '\0'; unp->un_pathlen = cnp->cn_namelen; } vp->v_type = vt; vp->v_data = unp; /* * TODO: This is an imperfect check, as there's no guarantee that * the underlying filesystems will always return vnode pointers * for the root inodes that match our cached values. To reduce * the likelihood of failure, for example in the case where either * vnode has been forcibly doomed, we check both pointers and set * VV_ROOT if either matches. */ if (ump->um_uppervp == uppervp || ump->um_lowervp == lowervp) vp->v_vflag |= VV_ROOT; KASSERT(dvp != NULL || (vp->v_vflag & VV_ROOT) != 0, ("%s: NULL dvp for non-root vp %p", __func__, vp)); vn_lock_pair(lowervp, false, LK_EXCLUSIVE, uppervp, false, LK_EXCLUSIVE); error = insmntque1(vp, mp); if (error != 0) { unionfs_nodeget_cleanup(vp, unp); return (error); } if (lowervp != NULL && VN_IS_DOOMED(lowervp)) { vput(lowervp); unp->un_lowervp = lowervp = NULL; } if (uppervp != NULL && VN_IS_DOOMED(uppervp)) { vput(uppervp); unp->un_uppervp = uppervp = NULL; if (lowervp != NULLVP) vp->v_vnlock = lowervp->v_vnlock; } if (lowervp == NULL && uppervp == NULL) { unionfs_nodeget_cleanup(vp, unp); return (ENOENT); } vn_set_state(vp, VSTATE_CONSTRUCTED); if (dvp != NULLVP && vt == VDIR) *vpp = unionfs_ins_cached_vnode(unp, dvp); if (*vpp != NULLVP) { unionfs_nodeget_cleanup(vp, unp); vp = *vpp; } else { if (uppervp != NULL) VOP_UNLOCK(uppervp); if (lowervp != NULL) VOP_UNLOCK(lowervp); *vpp = vp; } unionfs_nodeget_out: if (lkflags & LK_TYPE_MASK) vn_lock(vp, lkflags | LK_RETRY); return (0); } /* * Clean up the unionfs node. */ void unionfs_noderem(struct vnode *vp) { struct unionfs_node *unp, *unp_t1, *unp_t2; struct unionfs_node_hashhead *hd; struct unionfs_node_status *unsp, *unsp_tmp; struct vnode *lvp; struct vnode *uvp; struct vnode *dvp; int count; int writerefs; /* * The root vnode lock may be recursed during unmount, because * it may share the same lock as the unionfs mount's covered vnode, * which is locked across VFS_UNMOUNT(). This lock will then be * recursively taken during the vflush() issued by unionfs_unmount(). * But we still only need to lock the unionfs lock once, because only * one of those lock operations was taken against a unionfs vnode and * will be undone against a unionfs vnode. */ KASSERT(vp->v_vnlock->lk_recurse == 0 || (vp->v_vflag & VV_ROOT) != 0, ("%s: vnode %p locked recursively", __func__, vp)); if (lockmgr(&vp->v_lock, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) panic("%s: failed to acquire lock for vnode lock", __func__); /* * Use the interlock to protect the clearing of v_data to * prevent faults in unionfs_lock(). */ VI_LOCK(vp); unp = VTOUNIONFS(vp); lvp = unp->un_lowervp; uvp = unp->un_uppervp; dvp = unp->un_dvp; unp->un_lowervp = unp->un_uppervp = NULLVP; vp->v_vnlock = &(vp->v_lock); vp->v_data = NULL; vp->v_object = NULL; if (unp->un_hashtbl != NULL) { /* * Clear out any cached child vnodes. This should only * be necessary during forced unmount, when the vnode may * be reclaimed with a non-zero use count. Otherwise the * reference held by each child should prevent reclamation. */ for (count = 0; count <= UNIONFSHASHMASK; count++) { hd = unp->un_hashtbl + count; LIST_FOREACH_SAFE(unp_t1, hd, un_hash, unp_t2) { LIST_REMOVE(unp_t1, un_hash); unp_t1->un_hash.le_next = NULL; unp_t1->un_hash.le_prev = NULL; } } } VI_UNLOCK(vp); writerefs = atomic_load_int(&vp->v_writecount); VNASSERT(writerefs >= 0, vp, ("%s: write count %d, unexpected text ref", __func__, writerefs)); /* * 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 (writerefs > 0) { VNASSERT(uvp != NULL, vp, ("%s: write reference without upper vnode", __func__)); VOP_ADD_WRITECOUNT(uvp, -writerefs); } if (lvp != NULLVP) VOP_UNLOCK(lvp); if (uvp != NULLVP) VOP_UNLOCK(uvp); if (dvp != NULLVP) unionfs_rem_cached_vnode(unp, dvp); if (lvp != NULLVP) vrele(lvp); if (uvp != NULLVP) vrele(uvp); if (unp->un_path != NULL) { free(unp->un_path, M_UNIONFSPATH); unp->un_path = NULL; unp->un_pathlen = 0; } if (unp->un_hashtbl != NULL) { hashdestroy(unp->un_hashtbl, M_UNIONFSHASH, UNIONFSHASHMASK); } LIST_FOREACH_SAFE(unsp, &(unp->un_unshead), uns_list, unsp_tmp) { LIST_REMOVE(unsp, uns_list); free(unsp, M_TEMP); } if (dvp != NULLVP) { mtx_lock(&unionfs_deferred_rele_lock); STAILQ_INSERT_TAIL(&unionfs_deferred_rele_list, unp, un_rele); mtx_unlock(&unionfs_deferred_rele_lock); taskqueue_enqueue(taskqueue_unionfs_rele, &unionfs_deferred_rele_task); } else free(unp, M_UNIONFSNODE); } /* * Get the unionfs node status object for the vnode corresponding to unp, * for the process that owns td. Allocate a new status object if one * does not already exist. */ void unionfs_get_node_status(struct unionfs_node *unp, struct thread *td, struct unionfs_node_status **unspp) { struct unionfs_node_status *unsp; pid_t pid; pid = td->td_proc->p_pid; KASSERT(NULL != unspp, ("%s: NULL status", __func__)); ASSERT_VOP_ELOCKED(UNIONFSTOV(unp), __func__); LIST_FOREACH(unsp, &(unp->un_unshead), uns_list) { if (unsp->uns_pid == pid) { *unspp = unsp; return; } } /* create a new unionfs node status */ unsp = malloc(sizeof(struct unionfs_node_status), M_TEMP, M_WAITOK | M_ZERO); unsp->uns_pid = pid; LIST_INSERT_HEAD(&(unp->un_unshead), unsp, uns_list); *unspp = unsp; } /* * Remove the unionfs node status, if you can. * You need exclusive lock this vnode. */ void unionfs_tryrem_node_status(struct unionfs_node *unp, struct unionfs_node_status *unsp) { KASSERT(NULL != unsp, ("%s: NULL status", __func__)); ASSERT_VOP_ELOCKED(UNIONFSTOV(unp), __func__); if (0 < unsp->uns_lower_opencnt || 0 < unsp->uns_upper_opencnt) return; LIST_REMOVE(unsp, uns_list); free(unsp, M_TEMP); } /* * Create upper node attr. */ void unionfs_create_uppervattr_core(struct unionfs_mount *ump, struct vattr *lva, struct vattr *uva, struct thread *td) { VATTR_NULL(uva); uva->va_type = lva->va_type; uva->va_atime = lva->va_atime; uva->va_mtime = lva->va_mtime; uva->va_ctime = lva->va_ctime; switch (ump->um_copymode) { case UNIONFS_TRANSPARENT: uva->va_mode = lva->va_mode; uva->va_uid = lva->va_uid; uva->va_gid = lva->va_gid; break; case UNIONFS_MASQUERADE: if (ump->um_uid == lva->va_uid) { uva->va_mode = lva->va_mode & 077077; uva->va_mode |= (lva->va_type == VDIR ? ump->um_udir : ump->um_ufile) & 0700; uva->va_uid = lva->va_uid; uva->va_gid = lva->va_gid; } else { uva->va_mode = (lva->va_type == VDIR ? ump->um_udir : ump->um_ufile); uva->va_uid = ump->um_uid; uva->va_gid = ump->um_gid; } break; default: /* UNIONFS_TRADITIONAL */ uva->va_mode = 0777 & ~td->td_proc->p_pd->pd_cmask; uva->va_uid = ump->um_uid; uva->va_gid = ump->um_gid; break; } } /* * Create upper node attr. */ int unionfs_create_uppervattr(struct unionfs_mount *ump, struct vnode *lvp, struct vattr *uva, struct ucred *cred, struct thread *td) { struct vattr lva; int error; if ((error = VOP_GETATTR(lvp, &lva, cred))) return (error); unionfs_create_uppervattr_core(ump, &lva, uva, td); return (error); } /* * relookup * * dvp should be locked on entry and will be locked on return. * * If an error is returned, *vpp will be invalid, otherwise it will hold a * locked, referenced vnode. If *vpp == dvp then remember that only one * LK_EXCLUSIVE lock is held. */ int unionfs_relookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp, struct componentname *cn, struct thread *td, char *path, int pathlen, u_long nameiop) { int error; bool refstart; cn->cn_namelen = pathlen; cn->cn_pnbuf = path; cn->cn_nameiop = nameiop; cn->cn_flags = (LOCKPARENT | LOCKLEAF | ISLASTCN); cn->cn_lkflags = LK_EXCLUSIVE; cn->cn_cred = cnp->cn_cred; cn->cn_nameptr = cn->cn_pnbuf; refstart = false; if (nameiop == DELETE) { cn->cn_flags |= (cnp->cn_flags & DOWHITEOUT); } else if (nameiop == RENAME) { refstart = true; } else if (nameiop == CREATE) { cn->cn_flags |= NOCACHE; } vref(dvp); VOP_UNLOCK(dvp); if ((error = vfs_relookup(dvp, vpp, cn, refstart))) { vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY); } else vrele(dvp); KASSERT(cn->cn_pnbuf == path, ("%s: cn_pnbuf changed", __func__)); return (error); } /* * relookup for CREATE namei operation. * * dvp is unionfs vnode. dvp should be locked. * * If it called 'unionfs_copyfile' function by unionfs_link etc, * VOP_LOOKUP information is broken. * So it need relookup in order to create link etc. */ int unionfs_relookup_for_create(struct vnode *dvp, struct componentname *cnp, struct thread *td) { struct vnode *udvp; struct vnode *vp; struct componentname cn; int error; udvp = UNIONFSVPTOUPPERVP(dvp); vp = NULLVP; error = unionfs_relookup(udvp, &vp, cnp, &cn, td, cnp->cn_nameptr, cnp->cn_namelen, CREATE); if (error) return (error); if (vp != NULLVP) { if (udvp == vp) vrele(vp); else vput(vp); error = EEXIST; } return (error); } /* * relookup for DELETE namei operation. * * dvp is unionfs vnode. dvp should be locked. */ int unionfs_relookup_for_delete(struct vnode *dvp, struct componentname *cnp, struct thread *td) { struct vnode *udvp; struct vnode *vp; struct componentname cn; int error; udvp = UNIONFSVPTOUPPERVP(dvp); vp = NULLVP; error = unionfs_relookup(udvp, &vp, cnp, &cn, td, cnp->cn_nameptr, cnp->cn_namelen, DELETE); if (error) return (error); if (vp == NULLVP) error = ENOENT; else { if (udvp == vp) vrele(vp); else vput(vp); } return (error); } /* * relookup for RENAME namei operation. * * dvp is unionfs vnode. dvp should be locked. */ int unionfs_relookup_for_rename(struct vnode *dvp, struct componentname *cnp, struct thread *td) { struct vnode *udvp; struct vnode *vp; struct componentname cn; int error; udvp = UNIONFSVPTOUPPERVP(dvp); vp = NULLVP; error = unionfs_relookup(udvp, &vp, cnp, &cn, td, cnp->cn_nameptr, cnp->cn_namelen, RENAME); if (error) return (error); if (vp != NULLVP) { if (udvp == vp) vrele(vp); else vput(vp); } return (error); } /* * Update the unionfs_node. * * uvp is new locked upper vnode. unionfs vnode's lock will be exchanged to the * uvp's lock and lower's lock will be unlocked. */ static void unionfs_node_update(struct unionfs_node *unp, struct vnode *uvp, struct thread *td) { struct unionfs_node_hashhead *hd; struct vnode *vp; struct vnode *lvp; struct vnode *dvp; unsigned count, lockrec; vp = UNIONFSTOV(unp); lvp = unp->un_lowervp; ASSERT_VOP_ELOCKED(lvp, __func__); ASSERT_VOP_ELOCKED(uvp, __func__); dvp = unp->un_dvp; VNASSERT(vp->v_writecount == 0, vp, ("%s: non-zero writecount", __func__)); /* * Update the upper vnode's lock state to match the lower vnode, * and then switch the unionfs vnode's lock to the upper vnode. */ lockrec = lvp->v_vnlock->lk_recurse; for (count = 0; count < lockrec; count++) vn_lock(uvp, LK_EXCLUSIVE | LK_CANRECURSE | LK_RETRY); VI_LOCK(vp); unp->un_uppervp = uvp; vp->v_vnlock = uvp->v_vnlock; VI_UNLOCK(vp); /* * Re-cache the unionfs vnode against the upper vnode */ if (dvp != NULLVP && vp->v_type == VDIR) { VI_LOCK(dvp); if (unp->un_hash.le_prev != NULL) { LIST_REMOVE(unp, un_hash); hd = unionfs_get_hashhead(dvp, uvp); LIST_INSERT_HEAD(hd, unp, un_hash); } VI_UNLOCK(unp->un_dvp); } } /* * Create a new shadow dir. * * udvp should be locked on entry and will be locked on return. * * If no error returned, unp will be updated. */ int unionfs_mkshadowdir(struct unionfs_mount *ump, struct vnode *udvp, struct unionfs_node *unp, struct componentname *cnp, struct thread *td) { struct vnode *lvp; struct vnode *uvp; struct vattr va; struct vattr lva; struct nameidata nd; struct mount *mp; struct ucred *cred; struct ucred *credbk; struct uidinfo *rootinfo; int error; if (unp->un_uppervp != NULLVP) return (EEXIST); lvp = unp->un_lowervp; uvp = NULLVP; credbk = cnp->cn_cred; /* Authority change to root */ rootinfo = uifind((uid_t)0); cred = crdup(cnp->cn_cred); /* * The calls to chgproccnt() are needed to compensate for change_ruid() * calling chgproccnt(). */ chgproccnt(cred->cr_ruidinfo, 1, 0); change_euid(cred, rootinfo); change_ruid(cred, rootinfo); change_svuid(cred, (uid_t)0); uifree(rootinfo); cnp->cn_cred = cred; memset(&nd.ni_cnd, 0, sizeof(struct componentname)); NDPREINIT(&nd); if ((error = VOP_GETATTR(lvp, &lva, cnp->cn_cred))) goto unionfs_mkshadowdir_abort; if ((error = unionfs_relookup(udvp, &uvp, cnp, &nd.ni_cnd, td, cnp->cn_nameptr, cnp->cn_namelen, CREATE))) goto unionfs_mkshadowdir_abort; if (uvp != NULLVP) { if (udvp == uvp) vrele(uvp); else vput(uvp); error = EEXIST; goto unionfs_mkshadowdir_abort; } if ((error = vn_start_write(udvp, &mp, V_WAIT | V_PCATCH))) goto unionfs_mkshadowdir_abort; unionfs_create_uppervattr_core(ump, &lva, &va, td); /* * Temporarily NUL-terminate the current pathname component. * This function may be called during lookup operations in which * the current pathname component is not the leaf, meaning that * the NUL terminator is some distance beyond the end of the current * component. This *should* be fine, as cn_namelen will still * correctly indicate the length of only the current component, * but ZFS in particular does not respect cn_namelen in its VOP_MKDIR * implementation * Note that this assumes nd.ni_cnd.cn_pnbuf was allocated by * something like a local namei() operation and the temporary * NUL-termination will not have an effect on other threads. */ char *pathend = &nd.ni_cnd.cn_nameptr[nd.ni_cnd.cn_namelen]; char pathterm = *pathend; *pathend = '\0'; error = VOP_MKDIR(udvp, &uvp, &nd.ni_cnd, &va); *pathend = pathterm; if (!error) { /* * XXX The bug which cannot set uid/gid was corrected. * Ignore errors. */ va.va_type = VNON; VOP_SETATTR(uvp, &va, nd.ni_cnd.cn_cred); /* * VOP_SETATTR() may transiently drop uvp's lock, so it's * important to call it before unionfs_node_update() transfers * the unionfs vnode's lock from lvp to uvp; otherwise the * unionfs vnode itself would be transiently unlocked and * potentially doomed. */ unionfs_node_update(unp, uvp, td); } vn_finished_write(mp); unionfs_mkshadowdir_abort: cnp->cn_cred = credbk; chgproccnt(cred->cr_ruidinfo, -1, 0); crfree(cred); return (error); } static inline void unionfs_forward_vop_ref(struct vnode *basevp, int *lkflags) { ASSERT_VOP_LOCKED(basevp, __func__); *lkflags = VOP_ISLOCKED(basevp); vref(basevp); } /* * Prepare unionfs to issue a forwarded VOP to either the upper or lower * FS. This should be used for any VOP which may drop the vnode lock; * it is not required otherwise. * The unionfs vnode shares its lock with the base-layer vnode(s); if the * base FS must transiently drop its vnode lock, the unionfs vnode may * effectively become unlocked. During that window, a concurrent forced * unmount may doom the unionfs vnode, which leads to two significant * issues: * 1) Completion of, and return from, the unionfs VOP with the unionfs * vnode completely unlocked. When the unionfs vnode becomes doomed * it stops sharing its lock with the base vnode, so even if the * forwarded VOP reacquires the base vnode lock the unionfs vnode * lock will no longer be held. This can lead to violation of the * caller's sychronization requirements as well as various failed * locking assertions when DEBUG_VFS_LOCKS is enabled. * 2) Loss of reference on the base vnode. The caller is expected to * hold a v_usecount reference on the unionfs vnode, while the * unionfs vnode holds a reference on the base-layer vnode(s). But * these references are released when the unionfs vnode becomes * doomed, violating the base layer's expectation that its caller * must hold a reference to prevent vnode recycling. * * basevp1 and basevp2 represent two base-layer vnodes which are * expected to be locked when this function is called. basevp2 * may be NULL, but if not NULL basevp1 and basevp2 should represent * a parent directory and a filed linked to it, respectively. * lkflags1 and lkflags2 are output parameters that will store the * current lock status of basevp1 and basevp2, respectively. They * are intended to be passed as the lkflags1 and lkflags2 parameters * in the subsequent call to unionfs_forward_vop_finish_pair(). * lkflags2 may be NULL iff basevp2 is NULL. */ void unionfs_forward_vop_start_pair(struct vnode *basevp1, int *lkflags1, struct vnode *basevp2, int *lkflags2) { /* * Take an additional reference on the base-layer vnodes to * avoid loss of reference if the unionfs vnodes are doomed. */ unionfs_forward_vop_ref(basevp1, lkflags1); if (basevp2 != NULL) unionfs_forward_vop_ref(basevp2, lkflags2); } static inline bool unionfs_forward_vop_rele(struct vnode *unionvp, struct vnode *basevp, int lkflags) { bool unionvp_doomed; if (__predict_false(VTOUNIONFS(unionvp) == NULL)) { if ((lkflags & LK_EXCLUSIVE) != 0) ASSERT_VOP_ELOCKED(basevp, __func__); else ASSERT_VOP_LOCKED(basevp, __func__); unionvp_doomed = true; } else { vrele(basevp); unionvp_doomed = false; } return (unionvp_doomed); } /* * Indicate completion of a forwarded VOP previously prepared by * unionfs_forward_vop_start_pair(). * basevp1 and basevp2 must be the same values passed to the prior * call to unionfs_forward_vop_start_pair(). unionvp1 and unionvp2 * must be the unionfs vnodes that were initially above basevp1 and * basevp2, respectively. * basevp1 and basevp2 (if not NULL) must be locked when this function * is called, while unionvp1 and/or unionvp2 may be unlocked if either * unionfs vnode has become doomed. * lkflags1 and lkflag2 represent the locking flags that should be * used to re-lock unionvp1 and unionvp2, respectively, if either * vnode has become doomed. * * Returns true if any unionfs vnode was found to be doomed, false * otherwise. */ bool unionfs_forward_vop_finish_pair( struct vnode *unionvp1, struct vnode *basevp1, int lkflags1, struct vnode *unionvp2, struct vnode *basevp2, int lkflags2) { bool vp1_doomed, vp2_doomed; /* * If either vnode is found to have been doomed, set * a flag indicating that it needs to be re-locked. * Otherwise, simply drop the base-vnode reference that * was taken in unionfs_forward_vop_start(). */ vp1_doomed = unionfs_forward_vop_rele(unionvp1, basevp1, lkflags1); if (unionvp2 != NULL) vp2_doomed = unionfs_forward_vop_rele(unionvp2, basevp2, lkflags2); else vp2_doomed = false; /* * If any of the unionfs vnodes need to be re-locked, that * means the unionfs vnode's lock is now de-coupled from the * corresponding base vnode. We therefore need to drop the * base vnode lock (since nothing else will after this point), * and also release the reference taken in * unionfs_forward_vop_start_pair(). */ if (__predict_false(vp1_doomed && vp2_doomed)) VOP_VPUT_PAIR(basevp1, &basevp2, true); else if (__predict_false(vp1_doomed)) { /* * If basevp1 needs to be unlocked, then we may not * be able to safely unlock it with basevp2 still locked, * for the same reason that an ordinary VFS call would * need to use VOP_VPUT_PAIR() here. We might be able * to use VOP_VPUT_PAIR(..., false) here, but then we * would need to deal with the possibility of basevp2 * changing out from under us, which could result in * either the unionfs vnode becoming doomed or its * upper/lower vp no longer matching basevp2. Either * scenario would require at least re-locking the unionfs * vnode anyway. */ if (unionvp2 != NULL) { VOP_UNLOCK(unionvp2); vp2_doomed = true; } vput(basevp1); } else if (__predict_false(vp2_doomed)) vput(basevp2); if (__predict_false(vp1_doomed || vp2_doomed)) vn_lock_pair(unionvp1, !vp1_doomed, lkflags1, unionvp2, !vp2_doomed, lkflags2); return (vp1_doomed || vp2_doomed); } /* * Create a new whiteout. * * udvp and dvp should be locked on entry and will be locked on return. */ int unionfs_mkwhiteout(struct vnode *dvp, struct vnode *udvp, struct componentname *cnp, struct thread *td, char *path, int pathlen) { struct vnode *wvp; struct nameidata nd; struct mount *mp; int error; int lkflags; wvp = NULLVP; NDPREINIT(&nd); if ((error = unionfs_relookup(udvp, &wvp, cnp, &nd.ni_cnd, td, path, pathlen, CREATE))) { return (error); } if (wvp != NULLVP) { if (udvp == wvp) vrele(wvp); else vput(wvp); return (EEXIST); } if ((error = vn_start_write(udvp, &mp, V_WAIT | V_PCATCH))) goto unionfs_mkwhiteout_free_out; unionfs_forward_vop_start(udvp, &lkflags); error = VOP_WHITEOUT(udvp, &nd.ni_cnd, CREATE); unionfs_forward_vop_finish(dvp, udvp, lkflags); vn_finished_write(mp); unionfs_mkwhiteout_free_out: return (error); } /* * Create a new vnode for create a new shadow file. * * If an error is returned, *vpp will be invalid, otherwise it will hold a * locked, referenced and opened vnode. * * unp is never updated. */ static int unionfs_vn_create_on_upper(struct vnode **vpp, struct vnode *udvp, struct unionfs_node *unp, struct vattr *uvap, struct thread *td) { struct unionfs_mount *ump; struct vnode *vp; struct vnode *lvp; struct ucred *cred; struct vattr lva; struct nameidata nd; int fmode; int error; ump = MOUNTTOUNIONFSMOUNT(UNIONFSTOV(unp)->v_mount); vp = NULLVP; lvp = unp->un_lowervp; cred = td->td_ucred; fmode = FFLAGS(O_WRONLY | O_CREAT | O_TRUNC | O_EXCL); error = 0; if ((error = VOP_GETATTR(lvp, &lva, cred)) != 0) return (error); unionfs_create_uppervattr_core(ump, &lva, uvap, td); if (unp->un_path == NULL) panic("%s: NULL un_path", __func__); nd.ni_cnd.cn_namelen = unp->un_pathlen; nd.ni_cnd.cn_pnbuf = unp->un_path; nd.ni_cnd.cn_nameiop = CREATE; nd.ni_cnd.cn_flags = LOCKPARENT | LOCKLEAF | ISLASTCN; nd.ni_cnd.cn_lkflags = LK_EXCLUSIVE; nd.ni_cnd.cn_cred = cred; nd.ni_cnd.cn_nameptr = nd.ni_cnd.cn_pnbuf; NDPREINIT(&nd); vref(udvp); if ((error = vfs_relookup(udvp, &vp, &nd.ni_cnd, false)) != 0) goto unionfs_vn_create_on_upper_free_out2; vrele(udvp); if (vp != NULLVP) { if (vp == udvp) vrele(vp); else vput(vp); error = EEXIST; goto unionfs_vn_create_on_upper_free_out1; } if ((error = VOP_CREATE(udvp, &vp, &nd.ni_cnd, uvap)) != 0) goto unionfs_vn_create_on_upper_free_out1; if ((error = VOP_OPEN(vp, fmode, cred, td, NULL)) != 0) { vput(vp); goto unionfs_vn_create_on_upper_free_out1; } error = VOP_ADD_WRITECOUNT(vp, 1); CTR3(KTR_VFS, "%s: vp %p v_writecount increased to %d", __func__, vp, vp->v_writecount); if (error == 0) { *vpp = vp; } else { VOP_CLOSE(vp, fmode, cred, td); } unionfs_vn_create_on_upper_free_out1: VOP_UNLOCK(udvp); unionfs_vn_create_on_upper_free_out2: KASSERT(nd.ni_cnd.cn_pnbuf == unp->un_path, ("%s: cn_pnbuf changed", __func__)); return (error); } /* * Copy from lvp to uvp. * * lvp and uvp should be locked and opened on entry and will be locked and * opened on return. */ static int unionfs_copyfile_core(struct vnode *lvp, struct vnode *uvp, struct ucred *cred, struct thread *td) { char *buf; struct uio uio; struct iovec iov; off_t offset; int count; int error; int bufoffset; error = 0; memset(&uio, 0, sizeof(uio)); uio.uio_td = td; uio.uio_segflg = UIO_SYSSPACE; uio.uio_offset = 0; buf = malloc(MAXBSIZE, M_TEMP, M_WAITOK); while (error == 0) { offset = uio.uio_offset; uio.uio_iov = &iov; uio.uio_iovcnt = 1; iov.iov_base = buf; iov.iov_len = MAXBSIZE; uio.uio_resid = iov.iov_len; uio.uio_rw = UIO_READ; if ((error = VOP_READ(lvp, &uio, 0, cred)) != 0) break; if ((count = MAXBSIZE - uio.uio_resid) == 0) break; bufoffset = 0; while (bufoffset < count) { uio.uio_iov = &iov; uio.uio_iovcnt = 1; iov.iov_base = buf + bufoffset; iov.iov_len = count - bufoffset; uio.uio_offset = offset + bufoffset; uio.uio_resid = iov.iov_len; uio.uio_rw = UIO_WRITE; if ((error = VOP_WRITE(uvp, &uio, 0, cred)) != 0) break; bufoffset += (count - bufoffset) - uio.uio_resid; } uio.uio_offset = offset + bufoffset; } free(buf, M_TEMP); return (error); } /* * Copy file from lower to upper. * * If you need copy of the contents, set 1 to docopy. Otherwise, set 0 to * docopy. * * If no error returned, unp will be updated. */ int unionfs_copyfile(struct unionfs_node *unp, int docopy, struct ucred *cred, struct thread *td) { struct mount *mp; struct vnode *udvp; struct vnode *lvp; struct vnode *uvp; struct vattr uva; int error; lvp = unp->un_lowervp; uvp = NULLVP; if ((UNIONFSTOV(unp)->v_mount->mnt_flag & MNT_RDONLY)) return (EROFS); if (unp->un_dvp == NULLVP) return (EINVAL); if (unp->un_uppervp != NULLVP) return (EEXIST); udvp = VTOUNIONFS(unp->un_dvp)->un_uppervp; if (udvp == NULLVP) return (EROFS); if ((udvp->v_mount->mnt_flag & MNT_RDONLY)) return (EROFS); error = VOP_ACCESS(lvp, VREAD, cred, td); if (error != 0) return (error); if ((error = vn_start_write(udvp, &mp, V_WAIT | V_PCATCH)) != 0) return (error); error = unionfs_vn_create_on_upper(&uvp, udvp, unp, &uva, td); if (error != 0) { vn_finished_write(mp); return (error); } if (docopy != 0) { error = VOP_OPEN(lvp, FREAD, cred, td, NULL); if (error == 0) { error = unionfs_copyfile_core(lvp, uvp, cred, td); VOP_CLOSE(lvp, FREAD, cred, td); } } VOP_CLOSE(uvp, FWRITE, cred, td); VOP_ADD_WRITECOUNT_CHECKED(uvp, -1); CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d", __func__, uvp, uvp->v_writecount); vn_finished_write(mp); if (error == 0) { /* Reset the attributes. Ignore errors. */ uva.va_type = VNON; VOP_SETATTR(uvp, &uva, cred); } unionfs_node_update(unp, uvp, td); return (error); } /* * It checks whether vp can rmdir. (check empty) * * vp is unionfs vnode. * vp should be locked. */ int unionfs_check_rmdir(struct vnode *vp, struct ucred *cred, struct thread *td) { struct vnode *uvp; struct vnode *lvp; struct vnode *tvp; struct dirent *dp; struct dirent *edp; struct componentname cn; struct iovec iov; struct uio uio; struct vattr va; int error; int eofflag; int lookuperr; /* * The size of buf needs to be larger than DIRBLKSIZ. */ char buf[256 * 6]; ASSERT_VOP_ELOCKED(vp, __func__); eofflag = 0; uvp = UNIONFSVPTOUPPERVP(vp); lvp = UNIONFSVPTOLOWERVP(vp); /* check opaque */ if ((error = VOP_GETATTR(uvp, &va, cred)) != 0) return (error); if (va.va_flags & OPAQUE) return (0); /* open vnode */ #ifdef MAC if ((error = mac_vnode_check_open(cred, vp, VEXEC|VREAD)) != 0) return (error); #endif if ((error = VOP_ACCESS(vp, VEXEC|VREAD, cred, td)) != 0) return (error); if ((error = VOP_OPEN(vp, FREAD, cred, td, NULL)) != 0) return (error); uio.uio_rw = UIO_READ; uio.uio_segflg = UIO_SYSSPACE; uio.uio_td = td; uio.uio_offset = 0; #ifdef MAC error = mac_vnode_check_readdir(td->td_ucred, lvp); #endif while (!error && !eofflag) { iov.iov_base = buf; iov.iov_len = sizeof(buf); uio.uio_iov = &iov; uio.uio_iovcnt = 1; uio.uio_resid = iov.iov_len; error = VOP_READDIR(lvp, &uio, cred, &eofflag, NULL, NULL); if (error != 0) break; KASSERT(eofflag != 0 || uio.uio_resid < sizeof(buf), ("%s: empty read from lower FS", __func__)); edp = (struct dirent*)&buf[sizeof(buf) - uio.uio_resid]; for (dp = (struct dirent*)buf; !error && dp < edp; dp = (struct dirent*)((caddr_t)dp + dp->d_reclen)) { if (dp->d_type == DT_WHT || dp->d_fileno == 0 || (dp->d_namlen == 1 && dp->d_name[0] == '.') || (dp->d_namlen == 2 && !bcmp(dp->d_name, "..", 2))) continue; cn.cn_namelen = dp->d_namlen; cn.cn_pnbuf = NULL; cn.cn_nameptr = dp->d_name; cn.cn_nameiop = LOOKUP; cn.cn_flags = LOCKPARENT | LOCKLEAF | RDONLY | ISLASTCN; cn.cn_lkflags = LK_EXCLUSIVE; cn.cn_cred = cred; /* * check entry in lower. * Sometimes, readdir function returns * wrong entry. */ lookuperr = VOP_LOOKUP(lvp, &tvp, &cn); if (!lookuperr) vput(tvp); else continue; /* skip entry */ /* * check entry * If it has no exist/whiteout entry in upper, * directory is not empty. */ cn.cn_flags = LOCKPARENT | LOCKLEAF | RDONLY | ISLASTCN; lookuperr = VOP_LOOKUP(uvp, &tvp, &cn); if (!lookuperr) vput(tvp); /* ignore exist or whiteout entry */ if (!lookuperr || (lookuperr == ENOENT && (cn.cn_flags & ISWHITEOUT))) continue; error = ENOTEMPTY; } } /* close vnode */ VOP_CLOSE(vp, FREAD, cred, td); return (error); }