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747e915757
# mount -t union (or null) dir1 dir2 # mount -t union (or null) dir2 dir1 The function namei in union_mount calls union_root. The upper vnode has been already locked and vn_lock in union_root causes above panic. Add printf's included in `#ifdef DIAGNOSTIC' for EDEADLK cases.
561 lines
14 KiB
C
561 lines
14 KiB
C
/*
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* Copyright (c) 1994, 1995 The Regents of the University of California.
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* Copyright (c) 1994, 1995 Jan-Simon Pendry.
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* All rights reserved.
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*
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* This code is derived from software donated to Berkeley by
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* Jan-Simon Pendry.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)union_vfsops.c 8.20 (Berkeley) 5/20/95
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* $Id: union_vfsops.c,v 1.15 1997/04/14 10:52:25 kato Exp $
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*/
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/*
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* Union Layer
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/time.h>
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#include <sys/types.h>
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#include <sys/proc.h>
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#include <sys/vnode.h>
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#include <sys/mount.h>
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#include <sys/namei.h>
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#include <sys/malloc.h>
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#include <sys/filedesc.h>
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#include <sys/queue.h>
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#include <miscfs/union/union.h>
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extern int union_init __P((struct vfsconf *));
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extern int union_fhtovp __P((struct mount *mp, struct fid *fidp,
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struct mbuf *nam, struct vnode **vpp,
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int *exflagsp, struct ucred **credanonp));
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extern int union_mount __P((struct mount *mp, char *path, caddr_t data,
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struct nameidata *ndp, struct proc *p));
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extern int union_quotactl __P((struct mount *mp, int cmd, uid_t uid,
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caddr_t arg, struct proc *p));
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extern int union_root __P((struct mount *mp, struct vnode **vpp));
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extern int union_start __P((struct mount *mp, int flags, struct proc *p));
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extern int union_statfs __P((struct mount *mp, struct statfs *sbp,
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struct proc *p));
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extern int union_sync __P((struct mount *mp, int waitfor,
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struct ucred *cred, struct proc *p));
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extern int union_unmount __P((struct mount *mp, int mntflags,
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struct proc *p));
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extern int union_vget __P((struct mount *mp, ino_t ino,
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struct vnode **vpp));
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extern int union_vptofh __P((struct vnode *vp, struct fid *fhp));
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/*
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* Mount union filesystem
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*/
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int
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union_mount(mp, path, data, ndp, p)
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struct mount *mp;
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char *path;
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caddr_t data;
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struct nameidata *ndp;
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struct proc *p;
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{
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int error = 0;
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struct union_args args;
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struct vnode *lowerrootvp = NULLVP;
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struct vnode *upperrootvp = NULLVP;
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struct union_mount *um = 0;
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struct ucred *cred = 0;
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struct ucred *scred;
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struct vattr va;
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char *cp = 0;
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int len;
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u_int size;
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int islowerunlocked = 0;
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#ifdef UNION_DIAGNOSTIC
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printf("union_mount(mp = %x)\n", mp);
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#endif
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/*
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* Update is a no-op
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*/
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if (mp->mnt_flag & MNT_UPDATE) {
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/*
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* Need to provide.
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* 1. a way to convert between rdonly and rdwr mounts.
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* 2. support for nfs exports.
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*/
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error = EOPNOTSUPP;
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goto bad;
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}
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/*
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* Get argument
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*/
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error = copyin(data, (caddr_t)&args, sizeof(struct union_args));
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if (error)
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goto bad;
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lowerrootvp = mp->mnt_vnodecovered;
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VREF(lowerrootvp);
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/*
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* Unlock lower node to avoid deadlock.
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* (XXX) VOP_ISLOCKED is needed?
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*/
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if ((lowerrootvp->v_op == union_vnodeop_p) && VOP_ISLOCKED(lowerrootvp)) {
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VOP_UNLOCK(lowerrootvp, 0, p);
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islowerunlocked = 1;
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}
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/*
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* Find upper node.
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*/
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NDINIT(ndp, LOOKUP, FOLLOW|WANTPARENT,
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UIO_USERSPACE, args.target, p);
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error = namei(ndp);
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/*
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* Re-lock vnode.
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* (XXX) VOP_ISLOCKED is needed?
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*/
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if (islowerunlocked && !VOP_ISLOCKED(lowerrootvp))
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vn_lock(lowerrootvp, LK_EXCLUSIVE | LK_RETRY, p);
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if (error)
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goto bad;
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upperrootvp = ndp->ni_vp;
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vrele(ndp->ni_dvp);
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ndp->ni_dvp = NULL;
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/*
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* Check multi union mount to avoid `lock myself again' panic.
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*/
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if (upperrootvp == VTOUNION(lowerrootvp)->un_uppervp) {
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#ifdef DIAGNOSTIC
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printf("union_mount: multi union mount?\n");
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#endif
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error = EDEADLK;
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goto bad;
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}
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if (upperrootvp->v_type != VDIR) {
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error = EINVAL;
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goto bad;
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}
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um = (struct union_mount *) malloc(sizeof(struct union_mount),
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M_UFSMNT, M_WAITOK); /* XXX */
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/*
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* Keep a held reference to the target vnodes.
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* They are vrele'd in union_unmount.
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*
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* Depending on the _BELOW flag, the filesystems are
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* viewed in a different order. In effect, this is the
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* same as providing a mount under option to the mount syscall.
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*/
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um->um_op = args.mntflags & UNMNT_OPMASK;
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switch (um->um_op) {
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case UNMNT_ABOVE:
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um->um_lowervp = lowerrootvp;
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um->um_uppervp = upperrootvp;
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break;
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case UNMNT_BELOW:
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um->um_lowervp = upperrootvp;
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um->um_uppervp = lowerrootvp;
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break;
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case UNMNT_REPLACE:
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vrele(lowerrootvp);
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lowerrootvp = NULLVP;
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um->um_uppervp = upperrootvp;
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um->um_lowervp = lowerrootvp;
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break;
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default:
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error = EINVAL;
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goto bad;
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}
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/*
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* Unless the mount is readonly, ensure that the top layer
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* supports whiteout operations
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*/
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if ((mp->mnt_flag & MNT_RDONLY) == 0) {
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error = VOP_WHITEOUT(um->um_uppervp, (struct componentname *) 0, LOOKUP);
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if (error)
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goto bad;
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}
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um->um_cred = p->p_ucred;
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crhold(um->um_cred);
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um->um_cmode = UN_DIRMODE &~ p->p_fd->fd_cmask;
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/*
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* Depending on what you think the MNT_LOCAL flag might mean,
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* you may want the && to be || on the conditional below.
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* At the moment it has been defined that the filesystem is
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* only local if it is all local, ie the MNT_LOCAL flag implies
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* that the entire namespace is local. If you think the MNT_LOCAL
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* flag implies that some of the files might be stored locally
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* then you will want to change the conditional.
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*/
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if (um->um_op == UNMNT_ABOVE) {
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if (((um->um_lowervp == NULLVP) ||
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(um->um_lowervp->v_mount->mnt_flag & MNT_LOCAL)) &&
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(um->um_uppervp->v_mount->mnt_flag & MNT_LOCAL))
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mp->mnt_flag |= MNT_LOCAL;
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}
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/*
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* Copy in the upper layer's RDONLY flag. This is for the benefit
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* of lookup() which explicitly checks the flag, rather than asking
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* the filesystem for it's own opinion. This means, that an update
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* mount of the underlying filesystem to go from rdonly to rdwr
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* will leave the unioned view as read-only.
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*/
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mp->mnt_flag |= (um->um_uppervp->v_mount->mnt_flag & MNT_RDONLY);
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mp->mnt_data = (qaddr_t) um;
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vfs_getnewfsid(mp);
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(void) copyinstr(path, mp->mnt_stat.f_mntonname, MNAMELEN - 1, &size);
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bzero(mp->mnt_stat.f_mntonname + size, MNAMELEN - size);
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switch (um->um_op) {
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case UNMNT_ABOVE:
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cp = "<above>:";
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break;
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case UNMNT_BELOW:
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cp = "<below>:";
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break;
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case UNMNT_REPLACE:
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cp = "";
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break;
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}
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len = strlen(cp);
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bcopy(cp, mp->mnt_stat.f_mntfromname, len);
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cp = mp->mnt_stat.f_mntfromname + len;
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len = MNAMELEN - len;
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(void) copyinstr(args.target, cp, len - 1, &size);
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bzero(cp + size, len - size);
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(void)union_statfs(mp, &mp->mnt_stat, p);
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#ifdef UNION_DIAGNOSTIC
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printf("union_mount: from %s, on %s\n",
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mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
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#endif
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return (0);
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bad:
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if (um)
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free(um, M_UFSMNT);
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if (cred)
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crfree(cred);
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if (upperrootvp)
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vrele(upperrootvp);
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if (lowerrootvp)
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vrele(lowerrootvp);
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return (error);
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}
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/*
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* VFS start. Nothing needed here - the start routine
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* on the underlying filesystem(s) will have been called
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* when that filesystem was mounted.
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*/
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int
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union_start(mp, flags, p)
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struct mount *mp;
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int flags;
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struct proc *p;
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{
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return (0);
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}
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/*
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* Free reference to union layer
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*/
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int
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union_unmount(mp, mntflags, p)
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struct mount *mp;
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int mntflags;
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struct proc *p;
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{
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struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
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struct vnode *um_rootvp;
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int error;
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int freeing;
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int flags = 0;
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#ifdef UNION_DIAGNOSTIC
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printf("union_unmount(mp = %x)\n", mp);
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#endif
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if (mntflags & MNT_FORCE)
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flags |= FORCECLOSE;
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if (error = union_root(mp, &um_rootvp))
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return (error);
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/*
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* Keep flushing vnodes from the mount list.
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* This is needed because of the un_pvp held
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* reference to the parent vnode.
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* If more vnodes have been freed on a given pass,
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* the try again. The loop will iterate at most
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* (d) times, where (d) is the maximum tree depth
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* in the filesystem.
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*/
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for (freeing = 0; vflush(mp, um_rootvp, flags) != 0;) {
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struct vnode *vp;
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int n;
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/* count #vnodes held on mount list */
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for (n = 0, vp = mp->mnt_vnodelist.lh_first;
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vp != NULLVP;
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vp = vp->v_mntvnodes.le_next)
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n++;
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/* if this is unchanged then stop */
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if (n == freeing)
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break;
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/* otherwise try once more time */
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freeing = n;
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}
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/* At this point the root vnode should have a single reference */
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if (um_rootvp->v_usecount > 1) {
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vput(um_rootvp);
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return (EBUSY);
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}
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#ifdef UNION_DIAGNOSTIC
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vprint("union root", um_rootvp);
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#endif
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/*
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* Discard references to upper and lower target vnodes.
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*/
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if (um->um_lowervp)
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vrele(um->um_lowervp);
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vrele(um->um_uppervp);
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crfree(um->um_cred);
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/*
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* Release reference on underlying root vnode
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*/
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vput(um_rootvp);
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/*
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* And blow it away for future re-use
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*/
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vgone(um_rootvp);
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/*
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* Finally, throw away the union_mount structure
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*/
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free(mp->mnt_data, M_UFSMNT); /* XXX */
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mp->mnt_data = 0;
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return (0);
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}
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int
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union_root(mp, vpp)
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struct mount *mp;
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struct vnode **vpp;
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{
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struct proc *p = curproc; /* XXX */
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struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
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int error;
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int loselock;
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/*
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* Return locked reference to root.
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*/
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VREF(um->um_uppervp);
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if ((um->um_op == UNMNT_BELOW) &&
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VOP_ISLOCKED(um->um_uppervp)) {
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loselock = 1;
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} else {
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if (VOP_ISLOCKED(um->um_uppervp)) {
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/*
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* XXX
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* Should we check type of node?
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*/
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#ifdef DIAGNOSTIC
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printf("union_root: multi union mount?");
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#endif
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vrele(um->um_uppervp);
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return EDEADLK;
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} else
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vn_lock(um->um_uppervp, LK_EXCLUSIVE | LK_RETRY, p);
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loselock = 0;
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}
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if (um->um_lowervp)
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VREF(um->um_lowervp);
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error = union_allocvp(vpp, mp,
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(struct vnode *) 0,
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(struct vnode *) 0,
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(struct componentname *) 0,
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um->um_uppervp,
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um->um_lowervp,
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1);
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if (error) {
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if (loselock)
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vrele(um->um_uppervp);
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else
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vput(um->um_uppervp);
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if (um->um_lowervp)
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vrele(um->um_lowervp);
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} else {
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if (loselock)
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VTOUNION(*vpp)->un_flags &= ~UN_ULOCK;
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}
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return (error);
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}
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int
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union_statfs(mp, sbp, p)
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struct mount *mp;
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struct statfs *sbp;
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struct proc *p;
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{
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int error;
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struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
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struct statfs mstat;
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int lbsize;
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#ifdef UNION_DIAGNOSTIC
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printf("union_statfs(mp = %x, lvp = %x, uvp = %x)\n", mp,
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um->um_lowervp,
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um->um_uppervp);
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#endif
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bzero(&mstat, sizeof(mstat));
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if (um->um_lowervp) {
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error = VFS_STATFS(um->um_lowervp->v_mount, &mstat, p);
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if (error)
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return (error);
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}
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/* now copy across the "interesting" information and fake the rest */
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#if 0
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sbp->f_type = mstat.f_type;
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sbp->f_flags = mstat.f_flags;
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sbp->f_bsize = mstat.f_bsize;
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sbp->f_iosize = mstat.f_iosize;
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#endif
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lbsize = mstat.f_bsize;
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sbp->f_blocks = mstat.f_blocks;
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sbp->f_bfree = mstat.f_bfree;
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sbp->f_bavail = mstat.f_bavail;
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sbp->f_files = mstat.f_files;
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sbp->f_ffree = mstat.f_ffree;
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error = VFS_STATFS(um->um_uppervp->v_mount, &mstat, p);
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if (error)
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return (error);
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sbp->f_flags = mstat.f_flags;
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sbp->f_bsize = mstat.f_bsize;
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sbp->f_iosize = mstat.f_iosize;
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/*
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* if the lower and upper blocksizes differ, then frig the
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* block counts so that the sizes reported by df make some
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* kind of sense. none of this makes sense though.
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*/
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if (mstat.f_bsize != lbsize)
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sbp->f_blocks = sbp->f_blocks * lbsize / mstat.f_bsize;
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/*
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* The "total" fields count total resources in all layers,
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* the "free" fields count only those resources which are
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* free in the upper layer (since only the upper layer
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* is writeable).
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*/
|
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sbp->f_blocks += mstat.f_blocks;
|
|
sbp->f_bfree = mstat.f_bfree;
|
|
sbp->f_bavail = mstat.f_bavail;
|
|
sbp->f_files += mstat.f_files;
|
|
sbp->f_ffree = mstat.f_ffree;
|
|
|
|
if (sbp != &mp->mnt_stat) {
|
|
sbp->f_type = mp->mnt_vfc->vfc_typenum;
|
|
bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid));
|
|
bcopy(mp->mnt_stat.f_mntonname, sbp->f_mntonname, MNAMELEN);
|
|
bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN);
|
|
}
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* XXX - Assumes no data cached at union layer.
|
|
*/
|
|
#define union_sync ((int (*) __P((struct mount *, int, struct ucred *, \
|
|
struct proc *)))nullop)
|
|
|
|
#define union_fhtovp ((int (*) __P((struct mount *, struct fid *, \
|
|
struct mbuf *, struct vnode **, int *, struct ucred **)))eopnotsupp)
|
|
#define union_quotactl ((int (*) __P((struct mount *, int, uid_t, caddr_t, \
|
|
struct proc *)))eopnotsupp)
|
|
#define union_sysctl ((int (*) __P((int *, u_int, void *, size_t *, void *, \
|
|
size_t, struct proc *)))eopnotsupp)
|
|
#define union_vget ((int (*) __P((struct mount *, ino_t, struct vnode **))) \
|
|
eopnotsupp)
|
|
#define union_vptofh ((int (*) __P((struct vnode *, struct fid *)))eopnotsupp)
|
|
|
|
struct vfsops union_vfsops = {
|
|
union_mount,
|
|
union_start,
|
|
union_unmount,
|
|
union_root,
|
|
union_quotactl,
|
|
union_statfs,
|
|
union_sync,
|
|
union_vget,
|
|
union_fhtovp,
|
|
union_vptofh,
|
|
union_init,
|
|
};
|
|
|
|
VFS_SET(union_vfsops, union, MOUNT_UNION, VFCF_LOOPBACK);
|