504 lines
13 KiB
C
504 lines
13 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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* $FreeBSD$
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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/lock.h>
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#include <sys/mutex.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 <fs/unionfs/union.h>
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static MALLOC_DEFINE(M_UNIONFSMNT, "UNION mount", "UNION mount structure");
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extern vfs_init_t union_init;
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static vfs_root_t union_root;
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static vfs_nmount_t union_mount;
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static vfs_statfs_t union_statfs;
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static vfs_unmount_t union_unmount;
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/*
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* Mount union filesystem.
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*/
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static int
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union_mount(mp, ndp, td)
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struct mount *mp;
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struct nameidata *ndp;
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struct thread *td;
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{
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int error = 0;
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struct vfsoptlist *opts;
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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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char *cp = 0, *target;
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int op;
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int len;
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size_t size;
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struct componentname fakecn;
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UDEBUG(("union_mount(mp = %p)\n", (void *)mp));
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opts = mp->mnt_optnew;
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/*
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* Disable clustered write, otherwise system becomes unstable.
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*/
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mp->mnt_flag |= MNT_NOCLUSTERW;
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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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return (EOPNOTSUPP);
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/*
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* Get arguments.
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*/
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error = vfs_getopt(opts, "target", (void **)&target, &len);
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if (error || target[len - 1] != '\0')
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return (EINVAL);
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op = 0;
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if (vfs_getopt(opts, "below", NULL, NULL) == 0)
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op = UNMNT_BELOW;
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if (vfs_getopt(opts, "replace", NULL, NULL) == 0) {
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/* These options are mutually exclusive. */
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if (op)
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return (EINVAL);
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op = UNMNT_REPLACE;
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}
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/*
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* UNMNT_ABOVE is the default.
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*/
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if (op == 0)
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op = UNMNT_ABOVE;
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/*
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* Obtain lower vnode. Vnode is stored in mp->mnt_vnodecovered.
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* We need to reference it but not lock it.
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*/
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lowerrootvp = mp->mnt_vnodecovered;
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VREF(lowerrootvp);
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#if 0
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/*
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* Unlock lower node to avoid deadlock.
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*/
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if (lowerrootvp->v_op == union_vnodeop_p)
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VOP_UNLOCK(lowerrootvp, 0, td);
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#endif
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/*
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* Obtain upper vnode by calling namei() on the path. The
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* upperrootvp will be turned referenced but not locked.
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*/
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NDINIT(ndp, LOOKUP, FOLLOW|WANTPARENT, UIO_SYSSPACE, target, td);
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error = namei(ndp);
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#if 0
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if (lowerrootvp->v_op == union_vnodeop_p)
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vn_lock(lowerrootvp, LK_EXCLUSIVE | LK_RETRY, td);
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#endif
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if (error)
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goto bad;
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NDFREE(ndp, NDF_ONLY_PNBUF);
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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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UDEBUG(("mount_root UPPERVP %p locked = %d\n", upperrootvp,
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VOP_ISLOCKED(upperrootvp, NULL)));
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/*
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* Check multi union mount to avoid `lock myself again' panic.
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* Also require that it be a directory.
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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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/*
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* Allocate our union_mount structure and populate the fields.
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* The vnode references are stored in the union_mount as held,
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* unlocked references. Depending on the _BELOW flag, the
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* filesystems are viewed in a different order. In effect this
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* is the same as providing a mount-under option to the mount
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* syscall.
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*/
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um = (struct union_mount *) malloc(sizeof(struct union_mount),
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M_UNIONFSMNT, M_WAITOK | M_ZERO);
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um->um_op = op;
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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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upperrootvp = NULL;
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lowerrootvp = NULL;
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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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upperrootvp = NULL;
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lowerrootvp = NULL;
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break;
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case UNMNT_REPLACE:
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vrele(lowerrootvp);
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lowerrootvp = NULL;
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um->um_uppervp = upperrootvp;
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um->um_lowervp = lowerrootvp;
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upperrootvp = NULL;
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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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/*
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* XXX Fake up a struct componentname with only cn_nameiop
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* and cn_thread valid; union_whiteout() needs to use the
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* thread pointer to lock the vnode.
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*/
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bzero(&fakecn, sizeof(fakecn));
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fakecn.cn_nameiop = LOOKUP;
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fakecn.cn_thread = td;
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error = VOP_WHITEOUT(um->um_uppervp, &fakecn, LOOKUP);
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if (error)
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goto bad;
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}
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um->um_cred = crhold(td->td_ucred);
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FILEDESC_LOCK(td->td_proc->p_fd);
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um->um_cmode = UN_DIRMODE &~ td->td_proc->p_fd->fd_cmask;
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FILEDESC_UNLOCK(td->td_proc->p_fd);
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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 its 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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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) copystr(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, td);
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UDEBUG(("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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return (0);
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bad:
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if (um) {
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if (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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/* XXX other fields */
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free(um, M_UNIONFSMNT);
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}
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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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* Free reference to union layer.
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*/
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static int
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union_unmount(mp, mntflags, td)
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struct mount *mp;
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int mntflags;
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struct thread *td;
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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 freeing;
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int flags = 0;
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UDEBUG(("union_unmount(mp = %p)\n", (void *)mp));
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if (mntflags & MNT_FORCE)
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flags |= FORCECLOSE;
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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; (error = vflush(mp, 0, 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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mtx_lock(&mntvnode_mtx);
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n = 0;
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TAILQ_FOREACH(vp, &mp->mnt_nvnodelist, v_nmntvnodes)
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n++;
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mtx_unlock(&mntvnode_mtx);
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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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/*
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* If the most recent vflush failed, the filesystem is still busy.
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*/
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if (error)
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return (error);
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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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* Finally, throw away the union_mount structure.
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*/
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free(mp->mnt_data, M_UNIONFSMNT); /* XXX */
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mp->mnt_data = 0;
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return (0);
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}
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static 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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/*
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* Supply an unlocked reference to um_uppervp and to um_lowervp. It
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* is possible for um_uppervp to be locked without the associated
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* root union_node being locked. We let union_allocvp() deal with
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* it.
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*/
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UDEBUG(("union_root UPPERVP %p locked = %d\n", um->um_uppervp,
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VOP_ISLOCKED(um->um_uppervp, NULL)));
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VREF(um->um_uppervp);
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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, NULLVP, NULLVP, NULL,
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um->um_uppervp, um->um_lowervp, 1);
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UDEBUG(("error %d\n", error));
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UDEBUG(("union_root2 UPPERVP %p locked = %d\n", um->um_uppervp,
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VOP_ISLOCKED(um->um_uppervp, NULL)));
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return (error);
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}
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static int
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union_statfs(mp, sbp, td)
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struct mount *mp;
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struct statfs *sbp;
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struct thread *td;
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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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UDEBUG(("union_statfs(mp = %p, lvp = %p, uvp = %p)\n",
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(void *)mp, (void *)um->um_lowervp, (void *)um->um_uppervp));
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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, td);
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if (error)
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return (error);
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}
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/*
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* Now copy across the "interesting" information and fake the rest.
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*/
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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, td);
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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 = ((off_t) 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;
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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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sbp->f_type = mp->mnt_vfc->vfc_typenum;
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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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static struct vfsops union_vfsops = {
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.vfs_init = union_init,
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.vfs_nmount = union_mount,
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.vfs_root = union_root,
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.vfs_statfs = union_statfs,
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.vfs_unmount = union_unmount,
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};
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VFS_SET(union_vfsops, unionfs, VFCF_LOOPBACK);
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