/* $NetBSD: union_subr.c,v 1.10 2004/05/12 02:07:39 jrf 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 1.10 2004/05/12 02:07:39 jrf Exp $"); #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef DIAGNOSTIC #include #endif /* must be power of two, otherwise change UNION_HASH() */ #define NHASH 32 /* unsigned int ... */ #define UNION_HASH(u, l) \ (((((unsigned long) (u)) + ((unsigned long) l)) >> 8) & (NHASH-1)) static LIST_HEAD(unhead, union_node) unhead[NHASH]; static int unvplock[NHASH]; static int union_list_lock __P((int)); static void union_list_unlock __P((int)); void union_updatevp __P((struct union_node *, struct vnode *, struct vnode *)); static int union_relookup __P((struct union_mount *, struct vnode *, struct vnode **, struct componentname *, struct componentname *, const char *, int)); int union_vn_close __P((struct vnode *, int, struct ucred *, struct proc *)); static void union_dircache_r __P((struct vnode *, struct vnode ***, int *)); struct vnode *union_dircache __P((struct vnode *, struct proc *)); void union_init() { int i; for (i = 0; i < NHASH; i++) LIST_INIT(&unhead[i]); memset(unvplock, 0, sizeof(unvplock)); } /* * Free global unionfs resources. */ void union_done() { /* Make sure to unset the readdir hook. */ vn_union_readdir_hook = NULL; } static int union_list_lock(ix) int ix; { if (unvplock[ix] & UN_LOCKED) { unvplock[ix] |= UN_WANTED; (void) tsleep(&unvplock[ix], PINOD, "unionlk", 0); return (1); } unvplock[ix] |= UN_LOCKED; return (0); } static void union_list_unlock(ix) int ix; { unvplock[ix] &= ~UN_LOCKED; if (unvplock[ix] & UN_WANTED) { unvplock[ix] &= ~UN_WANTED; wakeup(&unvplock[ix]); } } void union_updatevp(un, uppervp, lowervp) struct union_node *un; struct vnode *uppervp; struct vnode *lowervp; { int ohash = UNION_HASH(un->un_uppervp, un->un_lowervp); int nhash = UNION_HASH(uppervp, lowervp); int docache = (lowervp != NULLVP || uppervp != NULLVP); int lhash, uhash; /* * Ensure locking is ordered from lower to higher * to avoid deadlocks. */ if (nhash < ohash) { lhash = nhash; uhash = ohash; } else { lhash = ohash; uhash = nhash; } if (lhash != uhash) while (union_list_lock(lhash)) continue; while (union_list_lock(uhash)) continue; if (ohash != nhash || !docache) { if (un->un_flags & UN_CACHED) { un->un_flags &= ~UN_CACHED; LIST_REMOVE(un, un_cache); } } if (ohash != nhash) union_list_unlock(ohash); if (un->un_lowervp != lowervp) { if (un->un_lowervp) { vrele(un->un_lowervp); if (un->un_path) { free(un->un_path, M_TEMP); un->un_path = 0; } if (un->un_dirvp) { vrele(un->un_dirvp); un->un_dirvp = NULLVP; } } un->un_lowervp = lowervp; un->un_lowersz = VNOVAL; } if (un->un_uppervp != uppervp) { if (un->un_uppervp) vrele(un->un_uppervp); un->un_uppervp = uppervp; un->un_uppersz = VNOVAL; } if (docache && (ohash != nhash)) { LIST_INSERT_HEAD(&unhead[nhash], un, un_cache); un->un_flags |= UN_CACHED; } union_list_unlock(nhash); } void union_newlower(un, lowervp) struct union_node *un; struct vnode *lowervp; { union_updatevp(un, un->un_uppervp, lowervp); } void union_newupper(un, uppervp) struct union_node *un; struct vnode *uppervp; { union_updatevp(un, uppervp, un->un_lowervp); } /* * 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. */ void union_newsize(vp, uppersz, lowersz) struct vnode *vp; off_t uppersz, lowersz; { struct union_node *un; off_t sz; /* only interested in regular files */ if (vp->v_type != VREG) return; un = VTOUNION(vp); 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; } if (sz != VNOVAL) { #ifdef UNION_DIAGNOSTIC printf("union: %s size now %qd\n", uppersz != VNOVAL ? "upper" : "lower", sz); #endif uvm_vnp_setsize(vp, sz); } } /* * allocate a union_node/vnode pair. the vnode is * referenced and locked. 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. * if supplied, (uppervp) is locked. * 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 singly-linked * 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. * * a single lock is kept for the entire list. this is * needed because the getnewvnode() function can block * waiting for a vnode to become free, in which case there * may be more than one process trying to get the same * vnode. this lock is only taken if we are going to * call getnewvnode, since the kernel itself is single-threaded. * * if an entry is found on the list, then call vget() to * take a reference. this is done because there may be * zero references to it and so it needs to removed from * the vnode free list. */ int union_allocvp(vpp, mp, undvp, dvp, cnp, uppervp, lowervp, docache) 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; struct vnode *xlowervp = NULLVP; struct union_mount *um = MOUNTTOUNIONMOUNT(mp); int hash = 0; int vflag; int try; if (uppervp == NULLVP && lowervp == NULLVP) panic("union: unidentifiable allocation"); if (uppervp && lowervp && (uppervp->v_type != lowervp->v_type)) { xlowervp = lowervp; lowervp = NULLVP; } /* detect the root vnode (and aliases) */ vflag = VLAYER; if ((uppervp == um->um_uppervp) && ((lowervp == NULLVP) || lowervp == um->um_lowervp)) { if (lowervp == NULLVP) { lowervp = um->um_lowervp; if (lowervp != NULLVP) VREF(lowervp); } vflag = VROOT; } loop: if (!docache) { un = 0; } else for (try = 0; try < 3; try++) { switch (try) { case 0: if (lowervp == NULLVP) continue; hash = UNION_HASH(uppervp, lowervp); break; case 1: if (uppervp == NULLVP) continue; hash = UNION_HASH(uppervp, NULLVP); break; case 2: if (lowervp == NULLVP) continue; hash = UNION_HASH(NULLVP, lowervp); break; } while (union_list_lock(hash)) continue; for (un = unhead[hash].lh_first; un != 0; un = un->un_cache.le_next) { if ((un->un_lowervp == lowervp || un->un_lowervp == NULLVP) && (un->un_uppervp == uppervp || un->un_uppervp == NULLVP) && (UNIONTOV(un)->v_mount == mp)) { if (vget(UNIONTOV(un), 0)) { union_list_unlock(hash); goto loop; } break; } } union_list_unlock(hash); if (un) break; } if (un) { /* * Obtain a lock on the union_node. * uppervp is locked, though un->un_uppervp * may not be. this doesn't break the locking * hierarchy since in the case that un->un_uppervp * is not yet locked it will be vrele'd and replaced * with uppervp. */ if ((dvp != NULLVP) && (uppervp == dvp)) { /* * Access ``.'', so (un) will already * be locked. Since this process has * the lock on (uppervp) no other * process can hold the lock on (un). */ #ifdef DIAGNOSTIC if ((un->un_flags & UN_LOCKED) == 0) panic("union: . not locked"); else if (curproc && un->un_pid != curproc->p_pid && un->un_pid > -1 && curproc->p_pid > -1) panic("union: allocvp not lock owner"); #endif } else { if (un->un_flags & UN_LOCKED) { vrele(UNIONTOV(un)); un->un_flags |= UN_WANTED; (void) tsleep(&un->un_flags, PINOD, "unionalloc", 0); goto loop; } un->un_flags |= UN_LOCKED; #ifdef DIAGNOSTIC if (curproc) un->un_pid = curproc->p_pid; else un->un_pid = -1; #endif } /* * At this point, the union_node is locked, * un->un_uppervp may not be locked, and uppervp * is locked or nil. */ /* * Save information about the upper layer. */ if (uppervp != un->un_uppervp) { union_newupper(un, uppervp); } else if (uppervp) { vrele(uppervp); } if (un->un_uppervp) { un->un_flags |= UN_ULOCK; un->un_flags &= ~UN_KLOCK; } /* * 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_hash = cnp->cn_hash; 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); return (0); } if (docache) { /* * otherwise lock the vp list while we call getnewvnode * since that can block. */ hash = UNION_HASH(uppervp, lowervp); if (union_list_lock(hash)) goto loop; } error = getnewvnode(VT_UNION, mp, union_vnodeop_p, vpp); if (error) { if (uppervp) { if (dvp == uppervp) vrele(uppervp); else vput(uppervp); } if (lowervp) vrele(lowervp); goto out; } MALLOC((*vpp)->v_data, void *, sizeof(struct union_node), M_TEMP, M_WAITOK); (*vpp)->v_flag |= vflag; (*vpp)->v_vnlock = NULL; /* Make upper layers call VOP_LOCK */ if (uppervp) (*vpp)->v_type = uppervp->v_type; else (*vpp)->v_type = lowervp->v_type; un = VTOUNION(*vpp); un->un_vnode = *vpp; un->un_uppervp = uppervp; un->un_uppersz = VNOVAL; un->un_lowervp = lowervp; un->un_lowersz = VNOVAL; un->un_pvp = undvp; if (undvp != NULLVP) VREF(undvp); un->un_dircache = 0; un->un_openl = 0; un->un_flags = UN_LOCKED; if (un->un_uppervp) un->un_flags |= UN_ULOCK; #ifdef DIAGNOSTIC if (curproc) un->un_pid = curproc->p_pid; else un->un_pid = -1; #endif if (cnp && (lowervp != NULLVP)) { un->un_hash = cnp->cn_hash; 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_hash = 0; un->un_path = 0; un->un_dirvp = 0; } if (docache) { LIST_INSERT_HEAD(&unhead[hash], un, un_cache); un->un_flags |= UN_CACHED; } if (xlowervp) vrele(xlowervp); out: if (docache) union_list_unlock(hash); return (error); } int union_freevp(vp) struct vnode *vp; { struct union_node *un = VTOUNION(vp); if (un->un_flags & UN_CACHED) { un->un_flags &= ~UN_CACHED; LIST_REMOVE(un, un_cache); } 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); FREE(vp->v_data, M_TEMP); vp->v_data = 0; 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(fvp, tvp, cred, p) struct vnode *fvp; struct vnode *tvp; struct ucred *cred; struct proc *p; { char *buf; 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_procp = p; uio.uio_segflg = UIO_SYSSPACE; uio.uio_offset = 0; VOP_UNLOCK(fvp, 0); /* XXX */ VOP_LEASE(fvp, p, cred, LEASE_READ); vn_lock(fvp, LK_EXCLUSIVE | LK_RETRY); /* XXX */ VOP_UNLOCK(tvp, 0); /* XXX */ VOP_LEASE(tvp, p, cred, LEASE_WRITE); vn_lock(tvp, LK_EXCLUSIVE | LK_RETRY); /* XXX */ buf = 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 = buf; 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 = buf; 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(buf, M_TEMP); return (error); } /* * (un) is assumed to be locked on entry and remains * locked on exit. */ int union_copyup(un, docopy, cred, p) struct union_node *un; int docopy; struct ucred *cred; struct proc *p; { int error; struct mount *mp; struct vnode *lvp, *uvp; struct vattr lvattr, uvattr; if ((error = vn_start_write(un->un_dirvp, &mp, V_WAIT | V_PCATCH)) != 0) return (error); error = union_vn_create(&uvp, un, p); if (error) { vn_finished_write(mp, 0); return (error); } /* at this point, uppervp is locked */ union_newupper(un, uvp); un->un_flags |= UN_ULOCK; 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, p); if (error == 0) error = VOP_OPEN(lvp, FREAD, cred, p); if (error == 0) { error = union_copyfile(lvp, uvp, cred, p); (void) VOP_CLOSE(lvp, FREAD, cred, p); } 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, p); } VOP_UNLOCK(lvp, 0); #ifdef UNION_DIAGNOSTIC if (error == 0) uprintf("union: copied up %s\n", un->un_path); #endif } vn_finished_write(mp, 0); union_vn_close(uvp, FWRITE, cred, p); /* * 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, p); (void) VOP_OPEN(uvp, FREAD, cred, p); } un->un_openl = 0; VOP_UNLOCK(lvp, 0); } return (error); } static int union_relookup(um, dvp, vpp, cnp, cn, path, pathlen) struct union_mount *um; struct vnode *dvp; struct vnode **vpp; struct componentname *cnp; struct componentname *cn; const char *path; int pathlen; { int error; /* * A new componentname structure must be faked up because * there is no way to know where the upper level cnp came * from or what it is being used for. This must duplicate * some of the work done by NDINIT, some of the work done * by namei, some of the work done by lookup and some of * the work done by VOP_LOOKUP when given a CREATE flag. * Conclusion: Horrible. * * The pathname buffer will be PNBUF_PUT'd by VOP_MKDIR. */ cn->cn_namelen = pathlen; if ((cn->cn_namelen + 1) > MAXPATHLEN) return (ENAMETOOLONG); cn->cn_pnbuf = PNBUF_GET(); memcpy(cn->cn_pnbuf, path, cn->cn_namelen); cn->cn_pnbuf[cn->cn_namelen] = '\0'; cn->cn_nameiop = CREATE; cn->cn_flags = (LOCKPARENT|HASBUF|SAVENAME|SAVESTART|ISLASTCN); cn->cn_proc = cnp->cn_proc; if (um->um_op == UNMNT_ABOVE) cn->cn_cred = cnp->cn_cred; else cn->cn_cred = um->um_cred; cn->cn_nameptr = cn->cn_pnbuf; cn->cn_hash = cnp->cn_hash; cn->cn_consume = cnp->cn_consume; VREF(dvp); error = relookup(dvp, vpp, cn); if (!error) vrele(dvp); else { PNBUF_PUT(cn->cn_pnbuf); cn->cn_pnbuf = 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(um, dvp, cnp, vpp) struct union_mount *um; struct vnode *dvp; struct componentname *cnp; struct vnode **vpp; { int error; struct vattr va; struct proc *p = cnp->cn_proc; struct componentname cn; struct mount *mp; if ((error = vn_start_write(dvp, &mp, V_WAIT | V_PCATCH)) != 0) return (error); error = union_relookup(um, dvp, vpp, cnp, &cn, cnp->cn_nameptr, cnp->cn_namelen); if (error) { vn_finished_write(mp, 0); return (error); } if (*vpp) { VOP_ABORTOP(dvp, &cn); VOP_UNLOCK(dvp, 0); vrele(*vpp); vn_finished_write(mp, 0); *vpp = NULLVP; return (EEXIST); } /* * 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; /* VOP_LEASE: dvp is locked */ VOP_LEASE(dvp, p, cn.cn_cred, LEASE_WRITE); error = VOP_MKDIR(dvp, vpp, &cn, &va); vn_finished_write(mp, 0); 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. */ int union_mkwhiteout(um, dvp, cnp, path) struct union_mount *um; struct vnode *dvp; struct componentname *cnp; char *path; { int error; struct proc *p = cnp->cn_proc; struct vnode *wvp; struct componentname cn; struct mount *mp; VOP_UNLOCK(dvp, 0); if ((error = vn_start_write(dvp, &mp, V_WAIT | V_PCATCH)) != 0) return (error); error = union_relookup(um, dvp, &wvp, cnp, &cn, path, strlen(path)); if (error) { vn_finished_write(mp, 0); vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY); return (error); } if (wvp) { VOP_ABORTOP(dvp, &cn); vrele(dvp); vrele(wvp); vn_finished_write(mp, 0); return (EEXIST); } /* VOP_LEASE: dvp is locked */ VOP_LEASE(dvp, p, p->p_ucred, LEASE_WRITE); error = VOP_WHITEOUT(dvp, &cn, CREATE); if (error) VOP_ABORTOP(dvp, &cn); vrele(dvp); vn_finished_write(mp, 0); 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 relookup is told where to start. */ int union_vn_create(vpp, un, p) struct vnode **vpp; struct union_node *un; struct proc *p; { struct vnode *vp; struct ucred *cred = p->p_ucred; struct vattr vat; struct vattr *vap = &vat; int fmode = FFLAGS(O_WRONLY|O_CREAT|O_TRUNC|O_EXCL); int error; int cmode = UN_FILEMODE & ~p->p_cwdi->cwdi_cmask; struct componentname cn; *vpp = NULLVP; /* * Build a new componentname structure (for the same * reasons outlines in union_mkshadow). * The difference here is that the file is owned by * the current user, rather than by the person who * did the mount, since the current user needs to be * able to write the file (that's why it is being * copied in the first place). */ cn.cn_namelen = strlen(un->un_path); if ((cn.cn_namelen + 1) > MAXPATHLEN) return (ENAMETOOLONG); cn.cn_pnbuf = PNBUF_GET(); memcpy(cn.cn_pnbuf, un->un_path, cn.cn_namelen+1); cn.cn_nameiop = CREATE; cn.cn_flags = (LOCKPARENT|HASBUF|SAVENAME|SAVESTART|ISLASTCN); cn.cn_proc = p; cn.cn_cred = p->p_ucred; cn.cn_nameptr = cn.cn_pnbuf; cn.cn_hash = un->un_hash; cn.cn_consume = 0; VREF(un->un_dirvp); if ((error = relookup(un->un_dirvp, &vp, &cn)) != 0) return (error); vrele(un->un_dirvp); if (vp) { VOP_ABORTOP(un->un_dirvp, &cn); if (un->un_dirvp == vp) vrele(un->un_dirvp); else vput(un->un_dirvp); vrele(vp); return (EEXIST); } /* * 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; VOP_LEASE(un->un_dirvp, p, cred, LEASE_WRITE); if ((error = VOP_CREATE(un->un_dirvp, &vp, &cn, vap)) != 0) return (error); if ((error = VOP_OPEN(vp, fmode, cred, p)) != 0) { vput(vp); return (error); } vp->v_writecount++; *vpp = vp; return (0); } int union_vn_close(vp, fmode, cred, p) struct vnode *vp; int fmode; struct ucred *cred; struct proc *p; { if (fmode & FWRITE) --vp->v_writecount; return (VOP_CLOSE(vp, fmode, cred, p)); } void union_removed_upper(un) struct union_node *un; { #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 if (un->un_flags & UN_CACHED) { un->un_flags &= ~UN_CACHED; LIST_REMOVE(un, un_cache); } if (un->un_flags & UN_ULOCK) { un->un_flags &= ~UN_ULOCK; VOP_UNLOCK(un->un_uppervp, 0); } } #if 0 struct vnode * union_lowervp(vp) 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) == 0) return (un->un_lowervp); } return (NULLVP); } #endif /* * determine whether a whiteout is needed * during a remove/rmdir operation. */ int union_dowhiteout(un, cred, p) struct union_node *un; struct ucred *cred; struct proc *p; { struct vattr va; if (un->un_lowervp != NULLVP) return (1); if (VOP_GETATTR(un->un_uppervp, &va, cred, p) == 0 && (va.va_flags & OPAQUE)) return (1); return (0); } static void union_dircache_r(vp, vppp, cntp) 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(vp, p) struct vnode *vp; struct proc *p; { 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_uppervp) break; } while (*vpp != NULLVP); } if (*vpp == NULLVP) goto out; vn_lock(*vpp, LK_EXCLUSIVE | LK_RETRY); VREF(*vpp); error = union_allocvp(&nvp, vp->v_mount, NULLVP, NULLVP, 0, *vpp, NULLVP, 0); if (!error) { VTOUNION(vp)->un_dircache = 0; VTOUNION(nvp)->un_dircache = dircache; } out: VOP_UNLOCK(vp, 0); return (nvp); } void union_diruncache(un) struct union_node *un; { struct vnode **vpp; 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; } } /* * 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 proc *p) { struct vnode *vp = *vpp, *lvp; struct vattr va; int error; if (vp->v_op != union_vnodeop_p) return (0); if ((lvp = union_dircache(vp, p)) == NULLVP) return (0); /* * If the directory is opaque, * then don't show lower entries */ error = VOP_GETATTR(vp, &va, fp->f_cred, p); if (error || (va.va_flags & OPAQUE)) { vput(lvp); return (error); } error = VOP_OPEN(lvp, FREAD, fp->f_cred, p); if (error) { vput(lvp); return (error); } VOP_UNLOCK(lvp, 0); fp->f_data = lvp; fp->f_offset = 0; error = vn_close(vp, FREAD, fp->f_cred, p); if (error) return (error); *vpp = lvp; return (0); }