/* $NetBSD: union_subr.c,v 1.77.8.1 2020/08/27 09:08:39 martin Exp $ */ /* * Copyright (c) 1994 * The Regents of the University of California. All rights reserved. * * 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 */ /* * Copyright (c) 1994 Jan-Simon Pendry * * 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. 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. * * @(#)union_subr.c 8.20 (Berkeley) 5/20/95 */ #include __KERNEL_RCSID(0, "$NetBSD: union_subr.c,v 1.77.8.1 2020/08/27 09:08:39 martin Exp $"); #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include static LIST_HEAD(uhashhead, union_node) *uhashtbl; static u_long uhash_mask; /* size of hash table - 1 */ #define UNION_HASH(u, l) \ ((((u_long) (u) + (u_long) (l)) >> 8) & uhash_mask) #define NOHASH ((u_long)-1) static kmutex_t uhash_lock; static void union_newupper(struct union_node *, struct vnode *); static void union_newlower(struct union_node *, struct vnode *); static void union_ref(struct union_node *); static void union_rele(struct union_node *); static int union_do_lookup(struct vnode *, struct componentname *, kauth_cred_t, const char *); int union_vn_close(struct vnode *, int, kauth_cred_t, struct lwp *); static void union_dircache_r(struct vnode *, struct vnode ***, int *); struct vnode *union_dircache(struct vnode *, struct lwp *); void union_init(void) { mutex_init(&uhash_lock, MUTEX_DEFAULT, IPL_NONE); uhashtbl = hashinit(desiredvnodes, HASH_LIST, true, &uhash_mask); } void union_reinit(void) { struct union_node *un; struct uhashhead *oldhash, *hash; u_long oldmask, mask, val; int i; hash = hashinit(desiredvnodes, HASH_LIST, true, &mask); mutex_enter(&uhash_lock); oldhash = uhashtbl; oldmask = uhash_mask; uhashtbl = hash; uhash_mask = mask; for (i = 0; i <= oldmask; i++) { while ((un = LIST_FIRST(&oldhash[i])) != NULL) { LIST_REMOVE(un, un_cache); val = UNION_HASH(un->un_uppervp, un->un_lowervp); LIST_INSERT_HEAD(&hash[val], un, un_cache); } } mutex_exit(&uhash_lock); hashdone(oldhash, HASH_LIST, oldmask); } /* * Free global unionfs resources. */ void union_done(void) { hashdone(uhashtbl, HASH_LIST, uhash_mask); mutex_destroy(&uhash_lock); /* Make sure to unset the readdir hook. */ vn_union_readdir_hook = NULL; } void union_newlower(struct union_node *un, struct vnode *lowervp) { int ohash = UNION_HASH(un->un_uppervp, un->un_lowervp); int nhash = UNION_HASH(un->un_uppervp, lowervp); if (un->un_lowervp == lowervp) return; KASSERT(VOP_ISLOCKED(UNIONTOV(un)) == LK_EXCLUSIVE); KASSERT(un->un_lowervp == NULL); mutex_enter(&uhash_lock); if (ohash != nhash && (un->un_cflags & UN_CACHED)) { un->un_cflags &= ~UN_CACHED; LIST_REMOVE(un, un_cache); } mutex_enter(&un->un_lock); un->un_lowervp = lowervp; un->un_lowersz = VNOVAL; mutex_exit(&un->un_lock); if (ohash != nhash) { LIST_INSERT_HEAD(&uhashtbl[nhash], un, un_cache); un->un_cflags |= UN_CACHED; } mutex_exit(&uhash_lock); } void union_newupper(struct union_node *un, struct vnode *uppervp) { int ohash = UNION_HASH(un->un_uppervp, un->un_lowervp); int nhash = UNION_HASH(uppervp, un->un_lowervp); struct vop_lock_args lock_ap; struct vop_unlock_args unlock_ap; int error __diagused; if (un->un_uppervp == uppervp) return; KASSERT(VOP_ISLOCKED(UNIONTOV(un)) == LK_EXCLUSIVE); KASSERT(un->un_uppervp == NULL); /* * We have to transfer the vnode lock from the union vnode to * the upper vnode. Lock the upper vnode first. We cannot use * VOP_LOCK() here as it would break the fstrans state. */ lock_ap.a_desc = VDESC(vop_lock); lock_ap.a_vp = uppervp; lock_ap.a_flags = LK_EXCLUSIVE; error = VCALL(lock_ap.a_vp, VOFFSET(vop_lock), &lock_ap); KASSERT(error == 0); mutex_enter(&uhash_lock); if (ohash != nhash && (un->un_cflags & UN_CACHED)) { un->un_cflags &= ~UN_CACHED; LIST_REMOVE(un, un_cache); } mutex_enter(&un->un_lock); un->un_uppervp = uppervp; un->un_uppersz = VNOVAL; /* * With the upper vnode in place unlock the union vnode to * finalize the lock transfer. */ unlock_ap.a_desc = VDESC(vop_unlock); unlock_ap.a_vp = UNIONTOV(un); genfs_unlock(&unlock_ap); /* Update union vnode interlock. */ mutex_obj_hold(uppervp->v_interlock); uvm_obj_setlock(&UNIONTOV(un)->v_uobj, uppervp->v_interlock); mutex_exit(&un->un_lock); if (ohash != nhash) { LIST_INSERT_HEAD(&uhashtbl[nhash], un, un_cache); un->un_cflags |= UN_CACHED; } mutex_exit(&uhash_lock); } /* * Keep track of size changes in the underlying vnodes. * If the size changes, then callback to the vm layer * giving priority to the upper layer size. * * Mutex un_lock hold on entry and released on return. */ void union_newsize(struct vnode *vp, off_t uppersz, off_t lowersz) { struct union_node *un = VTOUNION(vp); off_t sz; KASSERT(mutex_owned(&un->un_lock)); /* only interested in regular files */ if (vp->v_type != VREG) { mutex_exit(&un->un_lock); uvm_vnp_setsize(vp, 0); return; } sz = VNOVAL; if ((uppersz != VNOVAL) && (un->un_uppersz != uppersz)) { un->un_uppersz = uppersz; if (sz == VNOVAL) sz = un->un_uppersz; } if ((lowersz != VNOVAL) && (un->un_lowersz != lowersz)) { un->un_lowersz = lowersz; if (sz == VNOVAL) sz = un->un_lowersz; } mutex_exit(&un->un_lock); if (sz != VNOVAL) { #ifdef UNION_DIAGNOSTIC printf("union: %s size now %qd\n", uppersz != VNOVAL ? "upper" : "lower", sz); #endif uvm_vnp_setsize(vp, sz); } } static void union_ref(struct union_node *un) { KASSERT(mutex_owned(&uhash_lock)); un->un_refs++; } static void union_rele(struct union_node *un) { mutex_enter(&uhash_lock); un->un_refs--; if (un->un_refs > 0) { mutex_exit(&uhash_lock); return; } if (un->un_cflags & UN_CACHED) { un->un_cflags &= ~UN_CACHED; LIST_REMOVE(un, un_cache); } mutex_exit(&uhash_lock); if (un->un_pvp != NULLVP) vrele(un->un_pvp); if (un->un_uppervp != NULLVP) vrele(un->un_uppervp); if (un->un_lowervp != NULLVP) vrele(un->un_lowervp); if (un->un_dirvp != NULLVP) vrele(un->un_dirvp); if (un->un_path) free(un->un_path, M_TEMP); mutex_destroy(&un->un_lock); free(un, M_TEMP); } /* * allocate a union_node/vnode pair. the vnode is * referenced and unlocked. the new vnode is returned * via (vpp). (mp) is the mountpoint of the union filesystem, * (dvp) is the parent directory where the upper layer object * should exist (but doesn't) and (cnp) is the componentname * information which is partially copied to allow the upper * layer object to be created at a later time. (uppervp) * and (lowervp) reference the upper and lower layer objects * being mapped. either, but not both, can be nil. * both, if supplied, are unlocked. * the reference is either maintained in the new union_node * object which is allocated, or they are vrele'd. * * all union_nodes are maintained on a hash * list. new nodes are only allocated when they cannot * be found on this list. entries on the list are * removed when the vfs reclaim entry is called. * * the vnode gets attached or referenced with vcache_get(). */ int union_allocvp( struct vnode **vpp, struct mount *mp, struct vnode *undvp, /* parent union vnode */ struct vnode *dvp, /* may be null */ struct componentname *cnp, /* may be null */ struct vnode *uppervp, /* may be null */ struct vnode *lowervp, /* may be null */ int docache) { int error; struct union_node *un = NULL, *un1; struct vnode *vp, *xlowervp = NULLVP; u_long hash[3]; int try; bool is_dotdot; is_dotdot = (dvp != NULL && cnp != NULL && (cnp->cn_flags & ISDOTDOT)); if (uppervp == NULLVP && lowervp == NULLVP) panic("union: unidentifiable allocation"); if (uppervp && lowervp && (uppervp->v_type != lowervp->v_type)) { xlowervp = lowervp; lowervp = NULLVP; } /* * If both uppervp and lowervp are not NULL we have to * search union nodes with one vnode as NULL too. */ hash[0] = UNION_HASH(uppervp, lowervp); if (uppervp == NULL || lowervp == NULL) { hash[1] = hash[2] = NOHASH; } else { hash[1] = UNION_HASH(uppervp, NULLVP); hash[2] = UNION_HASH(NULLVP, lowervp); } if (!docache) { un = NULL; goto found; } loop: mutex_enter(&uhash_lock); for (try = 0; try < 3; try++) { if (hash[try] == NOHASH) continue; LIST_FOREACH(un, &uhashtbl[hash[try]], un_cache) { if ((un->un_lowervp && un->un_lowervp != lowervp) || (un->un_uppervp && un->un_uppervp != uppervp) || un->un_mount != mp) continue; union_ref(un); mutex_exit(&uhash_lock); error = vcache_get(mp, &un, sizeof(un), &vp); KASSERT(error != 0 || UNIONTOV(un) == vp); union_rele(un); if (error == ENOENT) goto loop; else if (error) goto out; goto found; } } mutex_exit(&uhash_lock); found: if (un) { if (uppervp != dvp) { if (is_dotdot) VOP_UNLOCK(dvp); vn_lock(UNIONTOV(un), LK_EXCLUSIVE | LK_RETRY); if (is_dotdot) vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY); } /* * Save information about the upper layer. */ if (uppervp != un->un_uppervp) { union_newupper(un, uppervp); } else if (uppervp) { vrele(uppervp); } /* * Save information about the lower layer. * This needs to keep track of pathname * and directory information which union_vn_create * might need. */ if (lowervp != un->un_lowervp) { union_newlower(un, lowervp); if (cnp && (lowervp != NULLVP)) { un->un_path = malloc(cnp->cn_namelen+1, M_TEMP, M_WAITOK); memcpy(un->un_path, cnp->cn_nameptr, cnp->cn_namelen); un->un_path[cnp->cn_namelen] = '\0'; vref(dvp); un->un_dirvp = dvp; } } else if (lowervp) { vrele(lowervp); } *vpp = UNIONTOV(un); if (uppervp != dvp) VOP_UNLOCK(*vpp); error = 0; goto out; } un = malloc(sizeof(struct union_node), M_TEMP, M_WAITOK); mutex_init(&un->un_lock, MUTEX_DEFAULT, IPL_NONE); un->un_refs = 1; un->un_mount = mp; un->un_vnode = NULL; un->un_uppervp = uppervp; un->un_lowervp = lowervp; un->un_pvp = undvp; if (undvp != NULLVP) vref(undvp); un->un_dircache = 0; un->un_openl = 0; un->un_cflags = 0; un->un_hooknode = false; un->un_uppersz = VNOVAL; un->un_lowersz = VNOVAL; if (dvp && cnp && (lowervp != NULLVP)) { un->un_path = malloc(cnp->cn_namelen+1, M_TEMP, M_WAITOK); memcpy(un->un_path, cnp->cn_nameptr, cnp->cn_namelen); un->un_path[cnp->cn_namelen] = '\0'; vref(dvp); un->un_dirvp = dvp; } else { un->un_path = 0; un->un_dirvp = 0; } if (docache) { mutex_enter(&uhash_lock); LIST_FOREACH(un1, &uhashtbl[hash[0]], un_cache) { if (un1->un_lowervp == lowervp && un1->un_uppervp == uppervp && un1->un_mount == mp) { /* * Another thread beat us, push back freshly * allocated node and retry. */ mutex_exit(&uhash_lock); union_rele(un); goto loop; } } LIST_INSERT_HEAD(&uhashtbl[hash[0]], un, un_cache); un->un_cflags |= UN_CACHED; mutex_exit(&uhash_lock); } error = vcache_get(mp, &un, sizeof(un), vpp); KASSERT(error != 0 || UNIONTOV(un) == *vpp); union_rele(un); if (error == ENOENT) goto loop; out: if (xlowervp) vrele(xlowervp); return error; } int union_freevp(struct vnode *vp) { struct union_node *un = VTOUNION(vp); /* Detach vnode from union node. */ un->un_vnode = NULL; un->un_uppersz = VNOVAL; un->un_lowersz = VNOVAL; /* Detach union node from vnode. */ mutex_enter(vp->v_interlock); vp->v_data = NULL; mutex_exit(vp->v_interlock); union_rele(un); return 0; } int union_loadvnode(struct mount *mp, struct vnode *vp, const void *key, size_t key_len, const void **new_key) { struct vattr va; struct vnode *svp; struct union_node *un; struct union_mount *um; voff_t uppersz, lowersz; KASSERT(key_len == sizeof(un)); memcpy(&un, key, key_len); um = MOUNTTOUNIONMOUNT(mp); svp = (un->un_uppervp != NULLVP) ? un->un_uppervp : un->un_lowervp; vp->v_tag = VT_UNION; vp->v_op = union_vnodeop_p; vp->v_data = un; un->un_vnode = vp; vp->v_type = svp->v_type; if (svp->v_type == VCHR || svp->v_type == VBLK) spec_node_init(vp, svp->v_rdev); mutex_obj_hold(svp->v_interlock); uvm_obj_setlock(&vp->v_uobj, svp->v_interlock); /* detect the root vnode (and aliases) */ if ((un->un_uppervp == um->um_uppervp) && ((un->un_lowervp == NULLVP) || un->un_lowervp == um->um_lowervp)) { if (un->un_lowervp == NULLVP) { un->un_lowervp = um->um_lowervp; if (un->un_lowervp != NULLVP) vref(un->un_lowervp); } vp->v_vflag |= VV_ROOT; } uppersz = lowersz = VNOVAL; if (un->un_uppervp != NULLVP) { if (vn_lock(un->un_uppervp, LK_SHARED) == 0) { if (VOP_GETATTR(un->un_uppervp, &va, FSCRED) == 0) uppersz = va.va_size; VOP_UNLOCK(un->un_uppervp); } } if (un->un_lowervp != NULLVP) { if (vn_lock(un->un_lowervp, LK_SHARED) == 0) { if (VOP_GETATTR(un->un_lowervp, &va, FSCRED) == 0) lowersz = va.va_size; VOP_UNLOCK(un->un_lowervp); } } mutex_enter(&un->un_lock); union_newsize(vp, uppersz, lowersz); mutex_enter(&uhash_lock); union_ref(un); mutex_exit(&uhash_lock); *new_key = &vp->v_data; return 0; } /* * copyfile. copy the vnode (fvp) to the vnode (tvp) * using a sequence of reads and writes. both (fvp) * and (tvp) are locked on entry and exit. */ int union_copyfile(struct vnode *fvp, struct vnode *tvp, kauth_cred_t cred, struct lwp *l) { char *tbuf; struct uio uio; struct iovec iov; int error = 0; /* * strategy: * allocate a buffer of size MAXBSIZE. * loop doing reads and writes, keeping track * of the current uio offset. * give up at the first sign of trouble. */ uio.uio_offset = 0; UIO_SETUP_SYSSPACE(&uio); tbuf = malloc(MAXBSIZE, M_TEMP, M_WAITOK); /* ugly loop follows... */ do { off_t offset = uio.uio_offset; uio.uio_iov = &iov; uio.uio_iovcnt = 1; iov.iov_base = tbuf; iov.iov_len = MAXBSIZE; uio.uio_resid = iov.iov_len; uio.uio_rw = UIO_READ; error = VOP_READ(fvp, &uio, 0, cred); if (error == 0) { uio.uio_iov = &iov; uio.uio_iovcnt = 1; iov.iov_base = tbuf; iov.iov_len = MAXBSIZE - uio.uio_resid; uio.uio_offset = offset; uio.uio_rw = UIO_WRITE; uio.uio_resid = iov.iov_len; if (uio.uio_resid == 0) break; do { error = VOP_WRITE(tvp, &uio, 0, cred); } while ((uio.uio_resid > 0) && (error == 0)); } } while (error == 0); free(tbuf, M_TEMP); return (error); } /* * (un) is assumed to be locked on entry and remains * locked on exit. */ int union_copyup(struct union_node *un, int docopy, kauth_cred_t cred, struct lwp *l) { int error; struct vnode *lvp, *uvp; struct vattr lvattr, uvattr; error = union_vn_create(&uvp, un, l); if (error) return (error); union_newupper(un, uvp); lvp = un->un_lowervp; if (docopy) { /* * XX - should not ignore errors * from VOP_CLOSE */ vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY); error = VOP_GETATTR(lvp, &lvattr, cred); if (error == 0) error = VOP_OPEN(lvp, FREAD, cred); if (error == 0) { error = union_copyfile(lvp, uvp, cred, l); (void) VOP_CLOSE(lvp, FREAD, cred); } if (error == 0) { /* Copy permissions up too */ vattr_null(&uvattr); uvattr.va_mode = lvattr.va_mode; uvattr.va_flags = lvattr.va_flags; error = VOP_SETATTR(uvp, &uvattr, cred); } VOP_UNLOCK(lvp); #ifdef UNION_DIAGNOSTIC if (error == 0) uprintf("union: copied up %s\n", un->un_path); #endif } union_vn_close(uvp, FWRITE, cred, l); /* * Subsequent IOs will go to the top layer, so * call close on the lower vnode and open on the * upper vnode to ensure that the filesystem keeps * its references counts right. This doesn't do * the right thing with (cred) and (FREAD) though. * Ignoring error returns is not right, either. */ if (error == 0) { int i; vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY); for (i = 0; i < un->un_openl; i++) { (void) VOP_CLOSE(lvp, FREAD, cred); (void) VOP_OPEN(uvp, FREAD, cred); } un->un_openl = 0; VOP_UNLOCK(lvp); } return (error); } /* * Prepare the creation of a new node in the upper layer. * * (dvp) is the directory in which to create the new node. * it is locked on entry and exit. * (cnp) is the componentname to be created. * (cred, path, hash) are credentials, path and its hash to fill (cnp). */ static int union_do_lookup(struct vnode *dvp, struct componentname *cnp, kauth_cred_t cred, const char *path) { int error; struct vnode *vp; cnp->cn_nameiop = CREATE; cnp->cn_flags = LOCKPARENT | ISLASTCN; cnp->cn_cred = cred; cnp->cn_nameptr = path; cnp->cn_namelen = strlen(path); error = VOP_LOOKUP(dvp, &vp, cnp); if (error == 0) { KASSERT(vp != NULL); VOP_ABORTOP(dvp, cnp); vrele(vp); error = EEXIST; } else if (error == EJUSTRETURN) { error = 0; } return error; } /* * Create a shadow directory in the upper layer. * The new vnode is returned locked. * * (um) points to the union mount structure for access to the * the mounting process's credentials. * (dvp) is the directory in which to create the shadow directory. * it is unlocked on entry and exit. * (cnp) is the componentname to be created. * (vpp) is the returned newly created shadow directory, which * is returned locked. * * N.B. We still attempt to create shadow directories even if the union * is mounted read-only, which is a little nonintuitive. */ int union_mkshadow(struct union_mount *um, struct vnode *dvp, struct componentname *cnp, struct vnode **vpp) { int error; struct vattr va; struct componentname cn; char *pnbuf; if (cnp->cn_namelen + 1 > MAXPATHLEN) return ENAMETOOLONG; pnbuf = PNBUF_GET(); memcpy(pnbuf, cnp->cn_nameptr, cnp->cn_namelen); pnbuf[cnp->cn_namelen] = '\0'; vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY); error = union_do_lookup(dvp, &cn, (um->um_op == UNMNT_ABOVE ? cnp->cn_cred : um->um_cred), pnbuf); if (error) { VOP_UNLOCK(dvp); PNBUF_PUT(pnbuf); return error; } /* * policy: when creating the shadow directory in the * upper layer, create it owned by the user who did * the mount, group from parent directory, and mode * 777 modified by umask (ie mostly identical to the * mkdir syscall). (jsp, kb) */ vattr_null(&va); va.va_type = VDIR; va.va_mode = um->um_cmode; KASSERT(*vpp == NULL); error = VOP_MKDIR(dvp, vpp, &cn, &va); VOP_UNLOCK(dvp); PNBUF_PUT(pnbuf); return error; } /* * Create a whiteout entry in the upper layer. * * (um) points to the union mount structure for access to the * the mounting process's credentials. * (dvp) is the directory in which to create the whiteout. * it is locked on entry and exit. * (cnp) is the componentname to be created. * (un) holds the path and its hash to be created. */ int union_mkwhiteout(struct union_mount *um, struct vnode *dvp, struct componentname *cnp, struct union_node *un) { int error; struct componentname cn; error = union_do_lookup(dvp, &cn, (um->um_op == UNMNT_ABOVE ? cnp->cn_cred : um->um_cred), un->un_path); if (error) return error; error = VOP_WHITEOUT(dvp, &cn, CREATE); return error; } /* * union_vn_create: creates and opens a new shadow file * on the upper union layer. this function is similar * in spirit to calling vn_open but it avoids calling namei(). * the problem with calling namei is that a) it locks too many * things, and b) it doesn't start at the "right" directory, * whereas union_do_lookup is told where to start. */ int union_vn_create(struct vnode **vpp, struct union_node *un, struct lwp *l) { struct vnode *vp; kauth_cred_t cred = l->l_cred; struct vattr vat; struct vattr *vap = &vat; int fmode = FFLAGS(O_WRONLY|O_CREAT|O_TRUNC|O_EXCL); int error; int cmode = UN_FILEMODE & ~l->l_proc->p_cwdi->cwdi_cmask; struct componentname cn; *vpp = NULLVP; vn_lock(un->un_dirvp, LK_EXCLUSIVE | LK_RETRY); error = union_do_lookup(un->un_dirvp, &cn, l->l_cred, un->un_path); if (error) { VOP_UNLOCK(un->un_dirvp); return error; } /* * Good - there was no race to create the file * so go ahead and create it. The permissions * on the file will be 0666 modified by the * current user's umask. Access to the file, while * it is unioned, will require access to the top *and* * bottom files. Access when not unioned will simply * require access to the top-level file. * TODO: confirm choice of access permissions. */ vattr_null(vap); vap->va_type = VREG; vap->va_mode = cmode; vp = NULL; error = VOP_CREATE(un->un_dirvp, &vp, &cn, vap); if (error) { VOP_UNLOCK(un->un_dirvp); return error; } vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); VOP_UNLOCK(un->un_dirvp); error = VOP_OPEN(vp, fmode, cred); if (error) { vput(vp); return error; } vp->v_writecount++; VOP_UNLOCK(vp); *vpp = vp; return 0; } int union_vn_close(struct vnode *vp, int fmode, kauth_cred_t cred, struct lwp *l) { if (fmode & FWRITE) --vp->v_writecount; return (VOP_CLOSE(vp, fmode, cred)); } void union_removed_upper(struct union_node *un) { struct vnode *vp = UNIONTOV(un); vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); #if 1 /* * We do not set the uppervp to NULLVP here, because lowervp * may also be NULLVP, so this routine would end up creating * a bogus union node with no upper or lower VP (that causes * pain in many places that assume at least one VP exists). * Since we've removed this node from the cache hash chains, * it won't be found again. When all current holders * release it, union_inactive() will vgone() it. */ union_diruncache(un); #else union_newupper(un, NULLVP); #endif VOP_UNLOCK(vp); mutex_enter(&uhash_lock); if (un->un_cflags & UN_CACHED) { un->un_cflags &= ~UN_CACHED; LIST_REMOVE(un, un_cache); } mutex_exit(&uhash_lock); } #if 0 struct vnode * union_lowervp(struct vnode *vp) { struct union_node *un = VTOUNION(vp); if ((un->un_lowervp != NULLVP) && (vp->v_type == un->un_lowervp->v_type)) { if (vget(un->un_lowervp, 0, true /* wait */) == 0) return (un->un_lowervp); } return (NULLVP); } #endif /* * determine whether a whiteout is needed * during a remove/rmdir operation. */ int union_dowhiteout(struct union_node *un, kauth_cred_t cred) { struct vattr va; if (un->un_lowervp != NULLVP) return (1); if (VOP_GETATTR(un->un_uppervp, &va, cred) == 0 && (va.va_flags & OPAQUE)) return (1); return (0); } static void union_dircache_r(struct vnode *vp, struct vnode ***vppp, int *cntp) { struct union_node *un; if (vp->v_op != union_vnodeop_p) { if (vppp) { vref(vp); *(*vppp)++ = vp; if (--(*cntp) == 0) panic("union: dircache table too small"); } else { (*cntp)++; } return; } un = VTOUNION(vp); if (un->un_uppervp != NULLVP) union_dircache_r(un->un_uppervp, vppp, cntp); if (un->un_lowervp != NULLVP) union_dircache_r(un->un_lowervp, vppp, cntp); } struct vnode * union_dircache(struct vnode *vp, struct lwp *l) { int cnt; struct vnode *nvp = NULLVP; struct vnode **vpp; struct vnode **dircache; int error; vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); dircache = VTOUNION(vp)->un_dircache; nvp = NULLVP; if (dircache == 0) { cnt = 0; union_dircache_r(vp, 0, &cnt); cnt++; dircache = (struct vnode **) malloc(cnt * sizeof(struct vnode *), M_TEMP, M_WAITOK); vpp = dircache; union_dircache_r(vp, &vpp, &cnt); VTOUNION(vp)->un_dircache = dircache; *vpp = NULLVP; vpp = dircache + 1; } else { vpp = dircache; do { if (*vpp++ == VTOUNION(vp)->un_lowervp) break; } while (*vpp != NULLVP); } if (*vpp == NULLVP) goto out; vref(*vpp); error = union_allocvp(&nvp, vp->v_mount, NULLVP, NULLVP, 0, NULLVP, *vpp, 0); if (!error) { vn_lock(nvp, LK_EXCLUSIVE | LK_RETRY); VTOUNION(vp)->un_dircache = 0; VTOUNION(nvp)->un_hooknode = true; VTOUNION(nvp)->un_dircache = dircache; } out: VOP_UNLOCK(vp); return (nvp); } void union_diruncache(struct union_node *un) { struct vnode **vpp; KASSERT(VOP_ISLOCKED(UNIONTOV(un)) == LK_EXCLUSIVE); if (un->un_dircache != 0) { for (vpp = un->un_dircache; *vpp != NULLVP; vpp++) vrele(*vpp); free(un->un_dircache, M_TEMP); un->un_dircache = 0; } } /* * Check whether node can rmdir (check empty). */ int union_check_rmdir(struct union_node *un, kauth_cred_t cred) { int dirlen, eofflag, error; char *dirbuf; struct vattr va; struct vnode *tvp; struct dirent *dp, *edp; struct componentname cn; struct iovec aiov; struct uio auio; KASSERT(un->un_uppervp != NULL); /* Check upper for being opaque. */ KASSERT(VOP_ISLOCKED(un->un_uppervp)); error = VOP_GETATTR(un->un_uppervp, &va, cred); if (error || (va.va_flags & OPAQUE)) return error; if (un->un_lowervp == NULL) return 0; /* Check lower for being empty. */ vn_lock(un->un_lowervp, LK_SHARED | LK_RETRY); error = VOP_GETATTR(un->un_lowervp, &va, cred); if (error) { VOP_UNLOCK(un->un_lowervp); return error; } dirlen = va.va_blocksize; dirbuf = kmem_alloc(dirlen, KM_SLEEP); /* error = 0; */ eofflag = 0; auio.uio_offset = 0; do { aiov.iov_len = dirlen; aiov.iov_base = dirbuf; auio.uio_iov = &aiov; auio.uio_iovcnt = 1; auio.uio_resid = aiov.iov_len; auio.uio_rw = UIO_READ; UIO_SETUP_SYSSPACE(&auio); error = VOP_READDIR(un->un_lowervp, &auio, cred, &eofflag, NULL, NULL); if (error) break; edp = (struct dirent *)&dirbuf[dirlen - auio.uio_resid]; for (dp = (struct dirent *)dirbuf; error == 0 && dp < edp; dp = (struct dirent *)((char *)dp + dp->d_reclen)) { if (dp->d_reclen == 0) { error = ENOTEMPTY; break; } if (dp->d_type == DT_WHT || (dp->d_namlen == 1 && dp->d_name[0] == '.') || (dp->d_namlen == 2 && !memcmp(dp->d_name, "..", 2))) continue; /* Check for presence in the upper layer. */ cn.cn_nameiop = LOOKUP; cn.cn_flags = ISLASTCN | RDONLY; cn.cn_cred = cred; cn.cn_nameptr = dp->d_name; cn.cn_namelen = dp->d_namlen; error = VOP_LOOKUP(un->un_uppervp, &tvp, &cn); if (error == ENOENT && (cn.cn_flags & ISWHITEOUT)) { error = 0; continue; } if (error == 0) vrele(tvp); error = ENOTEMPTY; } } while (error == 0 && !eofflag); kmem_free(dirbuf, dirlen); VOP_UNLOCK(un->un_lowervp); return error; } /* * This hook is called from vn_readdir() to switch to lower directory * entry after the upper directory is read. */ int union_readdirhook(struct vnode **vpp, struct file *fp, struct lwp *l) { struct vnode *vp = *vpp, *lvp; struct vattr va; int error; if (vp->v_op != union_vnodeop_p) return (0); /* * If the directory is opaque, * then don't show lower entries */ vn_lock(vp, LK_SHARED | LK_RETRY); error = VOP_GETATTR(vp, &va, fp->f_cred); VOP_UNLOCK(vp); if (error || (va.va_flags & OPAQUE)) return error; if ((lvp = union_dircache(vp, l)) == NULLVP) return (0); error = VOP_OPEN(lvp, FREAD, fp->f_cred); if (error) { vput(lvp); return (error); } VOP_UNLOCK(lvp); fp->f_vnode = lvp; fp->f_offset = 0; error = vn_close(vp, FREAD, fp->f_cred); if (error) return (error); *vpp = lvp; return (0); }