2a31267e43
fixed (many due to changing semantics in other parts of the kernel and not
the original author's fault), including one critical one: unionfs could
cause UFS corruption in the fronting store due to calling VOP_OPEN for
writing without turning on vmio for the UFS vnode.
Most of the bugs were related to semantics changes in VOP calls, lock
ordering problems (causing deadlocks), improper handling of a read-only
backing store (such as an NFS mount), improper referencing and locking
of vnodes, not using real struct locks for vnode locking, not using
recursive locks when accessing the fronting store, and things like that.
New functionality has been added: unionfs now has mmap() support, but
only partially tested, and rename has been enhanced considerably.
There are still some things that unionfs cannot do. You cannot
rename a directory without confusing unionfs, and there are issues
with softlinks, hardlinks, and special files. unionfs mostly doesn't
understand them (and never did).
There are probably still panic situations, but hopefully no where near
as many as before this commit.
The unionfs in this commit has been tested overlayed on /usr/src
(backing /usr/src being a read-only NFS mount, fronting /usr/src being
a local filesystem). kernel builds have been tested, buildworld is
undergoing testing. More testing is necessary.
157 lines
5.8 KiB
C
157 lines
5.8 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.h 8.9 (Berkeley) 12/10/94
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* $FreeBSD$
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*/
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struct union_args {
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char *target; /* Target of loopback */
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int mntflags; /* Options on the mount */
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};
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#define UNMNT_ABOVE 0x0001 /* Target appears below mount point */
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#define UNMNT_BELOW 0x0002 /* Target appears below mount point */
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#define UNMNT_REPLACE 0x0003 /* Target replaces mount point */
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#define UNMNT_OPMASK 0x0003
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struct union_mount {
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struct vnode *um_uppervp; /* UN_ULOCK holds locking state */
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struct vnode *um_lowervp; /* Left unlocked */
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struct ucred *um_cred; /* Credentials of user calling mount */
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int um_cmode; /* cmask from mount process */
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int um_op; /* Operation mode */
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};
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#ifdef KERNEL
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#ifndef DIAGNOSTIC
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#define DIAGNOSTIC
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#endif
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/*
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* DEFDIRMODE is the mode bits used to create a shadow directory.
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*/
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#define VRWXMODE (VREAD|VWRITE|VEXEC)
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#define VRWMODE (VREAD|VWRITE)
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#define UN_DIRMODE ((VRWXMODE)|(VRWXMODE>>3)|(VRWXMODE>>6))
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#define UN_FILEMODE ((VRWMODE)|(VRWMODE>>3)|(VRWMODE>>6))
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/*
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* A cache of vnode references (hangs off v_data)
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*
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* Placing un_lock as the first elements theoretically allows us to
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* use the vop_stdlock functions. However, we need to make sure of
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* certain side effects so we will still punch in our own code.
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*/
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struct union_node {
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struct lock un_lock;
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LIST_ENTRY(union_node) un_cache; /* Hash chain */
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struct vnode *un_vnode; /* Back pointer */
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struct vnode *un_uppervp; /* overlaying object */
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struct vnode *un_lowervp; /* underlying object */
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struct vnode *un_dirvp; /* Parent dir of uppervp */
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struct vnode *un_pvp; /* Parent vnode */
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char *un_path; /* saved component name */
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int un_hash; /* saved un_path hash value */
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int un_openl; /* # of opens on lowervp */
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int un_exclcnt; /* exclusive count */
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unsigned int un_flags;
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struct vnode **un_dircache; /* cached union stack */
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off_t un_uppersz; /* size of upper object */
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off_t un_lowersz; /* size of lower object */
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#ifdef DIAGNOSTIC
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pid_t un_pid;
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#endif
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};
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/*
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* XXX UN_ULOCK - indicates that the uppervp is locked
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*
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* UN_CACHED - node is in the union cache
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*/
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/*#define UN_ULOCK 0x04*/ /* Upper node is locked */
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#define UN_CACHED 0x10 /* In union cache */
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/*
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* Hash table locking flags
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*/
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#define UNVP_WANT 0x01
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#define UNVP_LOCKED 0x02
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extern int union_allocvp __P((struct vnode **, struct mount *,
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struct vnode *,
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struct vnode *,
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struct componentname *, struct vnode *,
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struct vnode *, int));
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extern int union_freevp __P((struct vnode *));
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extern struct vnode *union_dircache __P((struct vnode *, struct proc *));
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extern int union_copyup __P((struct union_node *, int, struct ucred *,
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struct proc *));
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extern int union_dowhiteout __P((struct union_node *, struct ucred *,
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struct proc *));
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extern int union_mkshadow __P((struct union_mount *, struct vnode *,
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struct componentname *, struct vnode **));
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extern int union_mkwhiteout __P((struct union_mount *, struct vnode *,
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struct componentname *, char *));
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extern int union_cn_close __P((struct vnode *, int, struct ucred *,
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struct proc *));
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extern void union_removed_upper __P((struct union_node *un));
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extern struct vnode *union_lowervp __P((struct vnode *));
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extern void union_newsize __P((struct vnode *, off_t, off_t));
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extern void union_vm_coherency __P((struct vnode *, struct uio *, int));
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extern int (*union_dircheckp) __P((struct proc *, struct vnode **,
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struct file *));
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#define MOUNTTOUNIONMOUNT(mp) ((struct union_mount *)((mp)->mnt_data))
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#define VTOUNION(vp) ((struct union_node *)(vp)->v_data)
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#define UNIONTOV(un) ((un)->un_vnode)
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#define LOWERVP(vp) (VTOUNION(vp)->un_lowervp)
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#define UPPERVP(vp) (VTOUNION(vp)->un_uppervp)
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#define OTHERVP(vp) (UPPERVP(vp) ? UPPERVP(vp) : LOWERVP(vp))
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#define UDEBUG(x) if (uniondebug) printf x
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#define UDEBUG_ENABLED 1
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extern vop_t **union_vnodeop_p;
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extern struct vfsops union_vfsops;
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extern int uniondebug;
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#endif /* KERNEL */
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