c4a7b7e10c
Find enclosed a short bugfix to get the union filesystem up and running in FreeBSD-current. We don't think we've got all the problems yet but these fixes sort out the major ones (which mostly concert bad locking of vnodes), no doubt we'll post others as necessary. Known problems include the inability of the umount command (not the system call) to unmount unions in certain circumstances (this is due the way "realpath" works), and the failure of direntries to always get all available files in unioned subdirectories. We are, as they say, working on it. Submitted by: tim@cs.city.ac.uk (Tim Wilkinson)
561 lines
13 KiB
C
561 lines
13 KiB
C
/*
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* Copyright (c) 1994 The Regents of the University of California.
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* Copyright (c) 1994 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 8.7 (Berkeley) 3/5/94
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* $Id: union_vfsops.c,v 1.6 1994/10/10 07:55:47 phk 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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/*
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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;
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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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#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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* Take a copy of the process's credentials. This isn't
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* quite right since the euid will always be zero and we
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* want to get the "real" users credentials. So fix up
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* the uid field after taking the copy.
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*/
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cred = crdup(p->p_ucred);
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cred->cr_uid = p->p_cred->p_ruid;
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/*
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* Ensure the *real* user has write permission on the
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* mounted-on directory. This allows the mount_union
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* command to be made setuid root so allowing anyone
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* to do union mounts onto any directory on which they
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* have write permission and which they also own.
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*/
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error = VOP_GETATTR(mp->mnt_vnodecovered, &va, cred, p);
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if (error)
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goto bad;
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if ((va.va_uid != cred->cr_uid) &&
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(cred->cr_uid != 0)) {
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error = EACCES;
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goto bad;
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}
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error = VOP_ACCESS(mp->mnt_vnodecovered, VWRITE, cred, p);
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if (error)
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goto bad;
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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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* Find upper node. Use the real process credentials,
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* not the effective ones since this will have come
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* through a setuid process (mount_union). All this
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* messing around with permissions is entirely bogus
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* and should be removed by allowing any user straight
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* past the mount system call.
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*/
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scred = p->p_ucred;
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p->p_ucred = cred;
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NDINIT(ndp, LOOKUP, FOLLOW|WANTPARENT,
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UIO_USERSPACE, args.target, p);
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p->p_ucred = scred;
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error = namei(ndp);
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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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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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um->um_cred = 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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/*
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* This is a user mount. Privilege check for unmount
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* will be done in union_unmount.
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*/
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mp->mnt_flag |= MNT_USER;
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mp->mnt_data = (qaddr_t) um;
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getnewfsid(mp, MOUNT_UNION);
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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 (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 flags = 0;
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extern int doforce;
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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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/* only the mounter, or superuser can unmount */
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if ((p->p_cred->p_ruid != um->um_cred->cr_uid) &&
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(error = suser(p->p_ucred, &p->p_acflag)))
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return (error);
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if (mntflags & MNT_FORCE) {
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/* union can never be rootfs so don't check for it */
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if (!doforce)
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return (EINVAL);
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flags |= FORCECLOSE;
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}
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error = union_root(mp, &um_rootvp);
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if (error)
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return (error);
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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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error = vflush(mp, um_rootvp, flags);
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if (error) {
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vput(um_rootvp);
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return (error);
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}
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#ifdef UNION_DIAGNOSTIC
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vprint("alias root of lower", 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 union_mount *um = MOUNTTOUNIONMOUNT(mp);
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int error;
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int loselock;
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#ifdef UNION_DIAGNOSTIC
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printf("union_root(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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/*
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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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VOP_LOCK(um->um_uppervp);
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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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if (error) {
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if (!loselock)
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VOP_UNLOCK(um->um_uppervp);
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vrele(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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(*vpp)->v_flag |= VROOT;
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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_quotactl(mp, cmd, uid, arg, p)
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struct mount *mp;
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int cmd;
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uid_t uid;
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caddr_t arg;
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struct proc *p;
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{
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return (EOPNOTSUPP);
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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_type = MOUNT_UNION;
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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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sbp->f_bfree = sbp->f_bfree * lbsize / mstat.f_bsize;
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sbp->f_bavail = sbp->f_bavail * lbsize / mstat.f_bsize;
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}
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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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if (sbp != &mp->mnt_stat) {
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bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid));
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bcopy(mp->mnt_stat.f_mntonname, sbp->f_mntonname, MNAMELEN);
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bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN);
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}
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return (0);
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}
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int
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union_sync(mp, waitfor, cred, p)
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struct mount *mp;
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int waitfor;
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struct ucred *cred;
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struct proc *p;
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{
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/*
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* XXX - Assumes no data cached at union layer.
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*/
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return (0);
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}
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int
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union_vget(mp, ino, vpp)
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struct mount *mp;
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ino_t ino;
|
|
struct vnode **vpp;
|
|
{
|
|
|
|
return (EOPNOTSUPP);
|
|
}
|
|
|
|
int
|
|
union_fhtovp(mp, fidp, nam, vpp, exflagsp, credanonp)
|
|
struct mount *mp;
|
|
struct fid *fidp;
|
|
struct mbuf *nam;
|
|
struct vnode **vpp;
|
|
int *exflagsp;
|
|
struct ucred **credanonp;
|
|
{
|
|
|
|
return (EOPNOTSUPP);
|
|
}
|
|
|
|
int
|
|
union_vptofh(vp, fhp)
|
|
struct vnode *vp;
|
|
struct fid *fhp;
|
|
{
|
|
|
|
return (EOPNOTSUPP);
|
|
}
|
|
|
|
int union_init __P((void));
|
|
|
|
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, 0);
|