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freebsd-skq/sys/fs/unionfs/union_vnops.c
mckusick a3d0c189ea Add snapshots to the fast filesystem. Most of the changes support 
the gating of system calls that cause modifications to the underlying
filesystem. The gating can be enabled by any filesystem that needs
to consistently suspend operations by adding the vop_stdgetwritemount
to their set of vnops. Once gating is enabled, the function
vfs_write_suspend stops all new write operations to a filesystem,
allows any filesystem modifying system calls already in progress
to complete, then sync's the filesystem to disk and returns. The
function vfs_write_resume allows the suspended write operations to
begin again. Gating is not added by default for all filesystems as
for SMP systems it adds two extra locks to such critical kernel
paths as the write system call. Thus, gating should only be added
as needed.

Details on the use and current status of snapshots in FFS can be
found in /sys/ufs/ffs/README.snapshot so for brevity and timelyness
is not included here. Unless and until you create a snapshot file,
these changes should have no effect on your system (famous last words).
2000-07-11 22:07:57 +00:00

1999 lines
49 KiB
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/*
* Copyright (c) 1992, 1993, 1994, 1995 Jan-Simon Pendry.
* Copyright (c) 1992, 1993, 1994, 1995
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Jan-Simon Pendry.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)union_vnops.c 8.32 (Berkeley) 6/23/95
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/fcntl.h>
#include <sys/stat.h>
#include <sys/kernel.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/malloc.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/lock.h>
#include <sys/sysctl.h>
#include <miscfs/union/union.h>
#include <vm/vm.h>
#include <vm/vnode_pager.h>
#include <vm/vm_page.h>
#include <vm/vm_object.h>
int uniondebug = 0;
#if UDEBUG_ENABLED
SYSCTL_INT(_vfs, OID_AUTO, uniondebug, CTLFLAG_RW, &uniondebug, 0, "");
#else
SYSCTL_INT(_vfs, OID_AUTO, uniondebug, CTLFLAG_RD, &uniondebug, 0, "");
#endif
static int union_access __P((struct vop_access_args *ap));
static int union_advlock __P((struct vop_advlock_args *ap));
static int union_bmap __P((struct vop_bmap_args *ap));
static int union_close __P((struct vop_close_args *ap));
static int union_create __P((struct vop_create_args *ap));
static int union_fsync __P((struct vop_fsync_args *ap));
static int union_getattr __P((struct vop_getattr_args *ap));
static int union_inactive __P((struct vop_inactive_args *ap));
static int union_ioctl __P((struct vop_ioctl_args *ap));
static int union_lease __P((struct vop_lease_args *ap));
static int union_link __P((struct vop_link_args *ap));
static int union_lock __P((struct vop_lock_args *ap));
static int union_lookup __P((struct vop_lookup_args *ap));
static int union_lookup1 __P((struct vnode *udvp, struct vnode **dvp,
struct vnode **vpp,
struct componentname *cnp));
static int union_mkdir __P((struct vop_mkdir_args *ap));
static int union_mknod __P((struct vop_mknod_args *ap));
static int union_mmap __P((struct vop_mmap_args *ap));
static int union_open __P((struct vop_open_args *ap));
static int union_pathconf __P((struct vop_pathconf_args *ap));
static int union_print __P((struct vop_print_args *ap));
static int union_read __P((struct vop_read_args *ap));
static int union_readdir __P((struct vop_readdir_args *ap));
static int union_readlink __P((struct vop_readlink_args *ap));
static int union_getwritemount __P((struct vop_getwritemount_args *ap));
static int union_reclaim __P((struct vop_reclaim_args *ap));
static int union_remove __P((struct vop_remove_args *ap));
static int union_rename __P((struct vop_rename_args *ap));
static int union_revoke __P((struct vop_revoke_args *ap));
static int union_rmdir __P((struct vop_rmdir_args *ap));
static int union_poll __P((struct vop_poll_args *ap));
static int union_setattr __P((struct vop_setattr_args *ap));
static int union_strategy __P((struct vop_strategy_args *ap));
static int union_getpages __P((struct vop_getpages_args *ap));
static int union_putpages __P((struct vop_putpages_args *ap));
static int union_symlink __P((struct vop_symlink_args *ap));
static int union_unlock __P((struct vop_unlock_args *ap));
static int union_whiteout __P((struct vop_whiteout_args *ap));
static int union_write __P((struct vop_read_args *ap));
static __inline
struct vnode *
union_lock_upper(struct union_node *un, struct proc *p)
{
struct vnode *uppervp;
if ((uppervp = un->un_uppervp) != NULL) {
VREF(uppervp);
vn_lock(uppervp, LK_EXCLUSIVE | LK_CANRECURSE | LK_RETRY, p);
}
KASSERT((uppervp == NULL || uppervp->v_usecount > 0), ("uppervp usecount is 0"));
return(uppervp);
}
static __inline
void
union_unlock_upper(struct vnode *uppervp, struct proc *p)
{
vput(uppervp);
}
static __inline
struct vnode *
union_lock_other(struct union_node *un, struct proc *p)
{
struct vnode *vp;
if (un->un_uppervp != NULL) {
vp = union_lock_upper(un, p);
} else if ((vp = un->un_lowervp) != NULL) {
VREF(vp);
vn_lock(vp, LK_EXCLUSIVE | LK_CANRECURSE | LK_RETRY, p);
}
return(vp);
}
static __inline
void
union_unlock_other(struct vnode *vp, struct proc *p)
{
vput(vp);
}
/*
* union_lookup:
*
* udvp must be exclusively locked on call and will remain
* exclusively locked on return. This is the mount point
* for out filesystem.
*
* dvp Our base directory, locked and referenced.
* The passed dvp will be dereferenced and unlocked on return
* and a new dvp will be returned which is locked and
* referenced in the same variable.
*
* vpp is filled in with the result if no error occured,
* locked and ref'd.
*
* If an error is returned, *vpp is set to NULLVP. If no
* error occurs, *vpp is returned with a reference and an
* exclusive lock.
*/
static int
union_lookup1(udvp, pdvp, vpp, cnp)
struct vnode *udvp;
struct vnode **pdvp;
struct vnode **vpp;
struct componentname *cnp;
{
int error;
struct proc *p = cnp->cn_proc;
struct vnode *dvp = *pdvp;
struct vnode *tdvp;
struct mount *mp;
/*
* If stepping up the directory tree, check for going
* back across the mount point, in which case do what
* lookup would do by stepping back down the mount
* hierarchy.
*/
if (cnp->cn_flags & ISDOTDOT) {
while ((dvp != udvp) && (dvp->v_flag & VROOT)) {
/*
* Don't do the NOCROSSMOUNT check
* at this level. By definition,
* union fs deals with namespaces, not
* filesystems.
*/
tdvp = dvp;
dvp = dvp->v_mount->mnt_vnodecovered;
VREF(dvp);
vput(tdvp);
vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY, p);
}
}
/*
* Set return dvp to be the upperdvp 'parent directory.
*/
*pdvp = dvp;
/*
* If the VOP_LOOKUP call generates an error, tdvp is invalid and no
* changes will have been made to dvp, so we are set to return.
*/
error = VOP_LOOKUP(dvp, &tdvp, cnp);
if (error) {
UDEBUG(("dvp %p error %d flags %lx\n", dvp, error, cnp->cn_flags));
*vpp = NULL;
return (error);
}
/*
* The parent directory will have been unlocked, unless lookup
* found the last component or if dvp == tdvp (tdvp must be locked).
*
* We want our dvp to remain locked and ref'd. We also want tdvp
* to remain locked and ref'd.
*/
UDEBUG(("parentdir %p result %p flag %lx\n", dvp, tdvp, cnp->cn_flags));
if (dvp != tdvp && (cnp->cn_flags & ISLASTCN) == 0)
vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY, p);
/*
* Lastly check if the current node is a mount point in
* which case walk up the mount hierarchy making sure not to
* bump into the root of the mount tree (ie. dvp != udvp).
*
* We use dvp as a temporary variable here, it is no longer related
* to the dvp above. However, we have to ensure that both *pdvp and
* tdvp are locked on return.
*/
dvp = tdvp;
while (
dvp != udvp &&
(dvp->v_type == VDIR) &&
(mp = dvp->v_mountedhere)
) {
int relock_pdvp = 0;
if (vfs_busy(mp, 0, 0, p))
continue;
if (dvp == *pdvp)
relock_pdvp = 1;
vput(dvp);
dvp = NULL;
error = VFS_ROOT(mp, &dvp);
vfs_unbusy(mp, p);
if (relock_pdvp)
vn_lock(*pdvp, LK_EXCLUSIVE | LK_RETRY, p);
if (error) {
*vpp = NULL;
return (error);
}
}
*vpp = dvp;
return (0);
}
static int
union_lookup(ap)
struct vop_lookup_args /* {
struct vnodeop_desc *a_desc;
struct vnode *a_dvp;
struct vnode **a_vpp;
struct componentname *a_cnp;
} */ *ap;
{
int error;
int uerror, lerror;
struct vnode *uppervp, *lowervp;
struct vnode *upperdvp, *lowerdvp;
struct vnode *dvp = ap->a_dvp; /* starting dir */
struct union_node *dun = VTOUNION(dvp); /* associated union node */
struct componentname *cnp = ap->a_cnp;
struct proc *p = cnp->cn_proc;
int lockparent = cnp->cn_flags & LOCKPARENT;
struct union_mount *um = MOUNTTOUNIONMOUNT(dvp->v_mount);
struct ucred *saved_cred = NULL;
int iswhiteout;
struct vattr va;
*ap->a_vpp = NULLVP;
/*
* Disallow write attemps to the filesystem mounted read-only.
*/
if ((cnp->cn_flags & ISLASTCN) &&
(dvp->v_mount->mnt_flag & MNT_RDONLY) &&
(cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
return (EROFS);
}
/*
* For any lookup's we do, always return with the parent locked
*/
cnp->cn_flags |= LOCKPARENT;
lowerdvp = dun->un_lowervp;
uppervp = NULLVP;
lowervp = NULLVP;
iswhiteout = 0;
uerror = ENOENT;
lerror = ENOENT;
/*
* Get a private lock on uppervp and a reference, effectively
* taking it out of the union_node's control.
*
* We must lock upperdvp while holding our lock on dvp
* to avoid a deadlock.
*/
upperdvp = union_lock_upper(dun, p);
/*
* do the lookup in the upper level.
* if that level comsumes additional pathnames,
* then assume that something special is going
* on and just return that vnode.
*/
if (upperdvp != NULLVP) {
/*
* We do not have to worry about the DOTDOT case, we've
* already unlocked dvp.
*/
UDEBUG(("A %p\n", upperdvp));
/*
* Do the lookup. We must supply a locked and referenced
* upperdvp to the function and will get a new locked and
* referenced upperdvp back with the old having been
* dereferenced.
*
* If an error is returned, uppervp will be NULLVP. If no
* error occurs, uppervp will be the locked and referenced
* return vnode or possibly NULL, depending on what is being
* requested. It is possible that the returned uppervp
* will be the same as upperdvp.
*/
uerror = union_lookup1(um->um_uppervp, &upperdvp, &uppervp, cnp);
UDEBUG((
"uerror %d upperdvp %p %d/%d, uppervp %p ref=%d/lck=%d\n",
uerror,
upperdvp,
upperdvp->v_usecount,
VOP_ISLOCKED(upperdvp, NULL),
uppervp,
(uppervp ? uppervp->v_usecount : -99),
(uppervp ? VOP_ISLOCKED(uppervp, NULL) : -99)
));
/*
* Disallow write attemps to the filesystem mounted read-only.
*/
if (uerror == EJUSTRETURN && (cnp->cn_flags & ISLASTCN) &&
(dvp->v_mount->mnt_flag & MNT_RDONLY) &&
(cnp->cn_nameiop == CREATE || cnp->cn_nameiop == RENAME)) {
error = EROFS;
goto out;
}
/*
* Special case. If cn_consume != 0 skip out. The result
* of the lookup is transfered to our return variable. If
* an error occured we have to throw away the results.
*/
if (cnp->cn_consume != 0) {
if ((error = uerror) == 0) {
*ap->a_vpp = uppervp;
uppervp = NULL;
}
goto out;
}
/*
* Calculate whiteout, fall through
*/
if (uerror == ENOENT || uerror == EJUSTRETURN) {
if (cnp->cn_flags & ISWHITEOUT) {
iswhiteout = 1;
} else if (lowerdvp != NULLVP) {
int terror;
terror = VOP_GETATTR(upperdvp, &va,
cnp->cn_cred, cnp->cn_proc);
if (terror == 0 && (va.va_flags & OPAQUE))
iswhiteout = 1;
}
}
}
/*
* in a similar way to the upper layer, do the lookup
* in the lower layer. this time, if there is some
* component magic going on, then vput whatever we got
* back from the upper layer and return the lower vnode
* instead.
*/
if (lowerdvp != NULLVP && !iswhiteout) {
int nameiop;
UDEBUG(("B %p\n", lowerdvp));
/*
* Force only LOOKUPs on the lower node, since
* we won't be making changes to it anyway.
*/
nameiop = cnp->cn_nameiop;
cnp->cn_nameiop = LOOKUP;
if (um->um_op == UNMNT_BELOW) {
saved_cred = cnp->cn_cred;
cnp->cn_cred = um->um_cred;
}
/*
* We shouldn't have to worry about locking interactions
* between the lower layer and our union layer (w.r.t.
* `..' processing) because we don't futz with lowervp
* locks in the union-node instantiation code path.
*
* union_lookup1() requires lowervp to be locked on entry,
* and it will be unlocked on return. The ref count will
* not change. On return lowervp doesn't represent anything
* to us so we NULL it out.
*/
VREF(lowerdvp);
vn_lock(lowerdvp, LK_EXCLUSIVE | LK_RETRY, p);
lerror = union_lookup1(um->um_lowervp, &lowerdvp, &lowervp, cnp);
if (lowerdvp == lowervp)
vrele(lowerdvp);
else
vput(lowerdvp);
lowerdvp = NULL; /* lowerdvp invalid after vput */
if (um->um_op == UNMNT_BELOW)
cnp->cn_cred = saved_cred;
cnp->cn_nameiop = nameiop;
if (cnp->cn_consume != 0 || lerror == EACCES) {
if ((error = lerror) == 0) {
*ap->a_vpp = lowervp;
lowervp = NULL;
}
goto out;
}
} else {
UDEBUG(("C %p\n", lowerdvp));
if ((cnp->cn_flags & ISDOTDOT) && dun->un_pvp != NULLVP) {
if ((lowervp = LOWERVP(dun->un_pvp)) != NULL) {
VREF(lowervp);
vn_lock(lowervp, LK_EXCLUSIVE | LK_RETRY, p);
lerror = 0;
}
}
}
/*
* Ok. Now we have uerror, uppervp, upperdvp, lerror, and lowervp.
*
* 1. If both layers returned an error, select the upper layer.
*
* 2. If the upper layer faile and the bottom layer succeeded,
* two subcases occur:
*
* a. The bottom vnode is not a directory, in which case
* just return a new union vnode referencing an
* empty top layer and the existing bottom layer.
*
* b. The button vnode is a directory, in which case
* create a new directory in the top layer and
* and fall through to case 3.
*
* 3. If the top layer succeeded then return a new union
* vnode referencing whatever the new top layer and
* whatever the bottom layer returned.
*/
/* case 1. */
if ((uerror != 0) && (lerror != 0)) {
error = uerror;
goto out;
}
/* case 2. */
if (uerror != 0 /* && (lerror == 0) */ ) {
if (lowervp->v_type == VDIR) { /* case 2b. */
KASSERT(uppervp == NULL, ("uppervp unexpectedly non-NULL"));
/*
* oops, uppervp has a problem, we may have to shadow.
*/
uerror = union_mkshadow(um, upperdvp, cnp, &uppervp);
if (uerror) {
error = uerror;
goto out;
}
}
}
/*
* Must call union_allocvp with both the upper and lower vnodes
* referenced and the upper vnode locked. ap->a_vpp is returned
* referenced and locked. lowervp, uppervp, and upperdvp are
* absorbed by union_allocvp() whether it succeeds or fails.
*
* upperdvp is the parent directory of uppervp which may be
* different, depending on the path, from dvp->un_uppervp. That's
* why it is a separate argument. Note that it must be unlocked.
*
* dvp must be locked on entry to the call and will be locked on
* return.
*/
if (uppervp && uppervp != upperdvp)
VOP_UNLOCK(uppervp, 0, p);
if (lowervp)
VOP_UNLOCK(lowervp, 0, p);
if (upperdvp)
VOP_UNLOCK(upperdvp, 0, p);
error = union_allocvp(ap->a_vpp, dvp->v_mount, dvp, upperdvp, cnp,
uppervp, lowervp, 1);
UDEBUG(("Create %p = %p %p refs=%d\n", *ap->a_vpp, uppervp, lowervp, (*ap->a_vpp) ? ((*ap->a_vpp)->v_usecount) : -99));
uppervp = NULL;
upperdvp = NULL;
lowervp = NULL;
/*
* Termination Code
*
* - put away any extra junk laying around. Note that lowervp
* (if not NULL) will never be the same as *ap->a_vp and
* neither will uppervp, because when we set that state we
* NULL-out lowervp or uppervp. On the otherhand, upperdvp
* may match uppervp or *ap->a_vpp.
*
* - relock/unlock dvp if appropriate.
*/
out:
if (upperdvp) {
if (upperdvp == uppervp || upperdvp == *ap->a_vpp)
vrele(upperdvp);
else
vput(upperdvp);
}
if (uppervp)
vput(uppervp);
if (lowervp)
vput(lowervp);
/*
* Restore LOCKPARENT state
*/
if (!lockparent)
cnp->cn_flags &= ~LOCKPARENT;
UDEBUG(("Out %d vpp %p/%d lower %p upper %p\n", error, *ap->a_vpp,
((*ap->a_vpp) ? (*ap->a_vpp)->v_usecount : -99),
lowervp, uppervp));
/*
* dvp lock state, determine whether to relock dvp. dvp is expected
* to be locked on return if:
*
* - there was an error (except not EJUSTRETURN), or
* - we hit the last component and lockparent is true
*
* dvp_is_locked is the current state of the dvp lock, not counting
* the possibility that *ap->a_vpp == dvp (in which case it is locked
* anyway). Note that *ap->a_vpp == dvp only if no error occured.
*/
if (*ap->a_vpp != dvp) {
if ((error == 0 || error == EJUSTRETURN) &&
(!lockparent || (cnp->cn_flags & ISLASTCN) == 0)) {
VOP_UNLOCK(dvp, 0, p);
}
}
/*
* Diagnostics
*/
#ifdef DIAGNOSTIC
if (cnp->cn_namelen == 1 &&
cnp->cn_nameptr[0] == '.' &&
*ap->a_vpp != dvp) {
panic("union_lookup returning . (%p) not same as startdir (%p)", ap->a_vpp, dvp);
}
#endif
return (error);
}
/*
* union_create:
*
* a_dvp is locked on entry and remains locked on return. a_vpp is returned
* locked if no error occurs, otherwise it is garbage.
*/
static int
union_create(ap)
struct vop_create_args /* {
struct vnode *a_dvp;
struct vnode **a_vpp;
struct componentname *a_cnp;
struct vattr *a_vap;
} */ *ap;
{
struct union_node *dun = VTOUNION(ap->a_dvp);
struct componentname *cnp = ap->a_cnp;
struct proc *p = cnp->cn_proc;
struct vnode *dvp;
int error = EROFS;
if ((dvp = union_lock_upper(dun, p)) != NULL) {
struct vnode *vp;
struct mount *mp;
error = VOP_CREATE(dvp, &vp, cnp, ap->a_vap);
if (error == 0) {
mp = ap->a_dvp->v_mount;
VOP_UNLOCK(vp, 0, p);
UDEBUG(("ALLOCVP-1 FROM %p REFS %d\n", vp, vp->v_usecount));
error = union_allocvp(ap->a_vpp, mp, NULLVP, NULLVP,
cnp, vp, NULLVP, 1);
UDEBUG(("ALLOCVP-2B FROM %p REFS %d\n", *ap->a_vpp, vp->v_usecount));
}
union_unlock_upper(dvp, p);
}
return (error);
}
static int
union_whiteout(ap)
struct vop_whiteout_args /* {
struct vnode *a_dvp;
struct componentname *a_cnp;
int a_flags;
} */ *ap;
{
struct union_node *un = VTOUNION(ap->a_dvp);
struct componentname *cnp = ap->a_cnp;
struct vnode *uppervp;
int error = EOPNOTSUPP;
if ((uppervp = union_lock_upper(un, cnp->cn_proc)) != NULLVP) {
error = VOP_WHITEOUT(un->un_uppervp, cnp, ap->a_flags);
union_unlock_upper(uppervp, cnp->cn_proc);
}
return(error);
}
/*
* union_mknod:
*
* a_dvp is locked on entry and should remain locked on return.
* a_vpp is garbagre whether an error occurs or not.
*/
static int
union_mknod(ap)
struct vop_mknod_args /* {
struct vnode *a_dvp;
struct vnode **a_vpp;
struct componentname *a_cnp;
struct vattr *a_vap;
} */ *ap;
{
struct union_node *dun = VTOUNION(ap->a_dvp);
struct componentname *cnp = ap->a_cnp;
struct vnode *dvp;
int error = EROFS;
if ((dvp = union_lock_upper(dun, cnp->cn_proc)) != NULL) {
error = VOP_MKNOD(dvp, ap->a_vpp, cnp, ap->a_vap);
union_unlock_upper(dvp, cnp->cn_proc);
}
return (error);
}
/*
* union_open:
*
* run open VOP. When opening the underlying vnode we have to mimic
* vn_open. What we *really* need to do to avoid screwups if the
* open semantics change is to call vn_open(). For example, ufs blows
* up if you open a file but do not vmio it prior to writing.
*/
static int
union_open(ap)
struct vop_open_args /* {
struct vnodeop_desc *a_desc;
struct vnode *a_vp;
int a_mode;
struct ucred *a_cred;
struct proc *a_p;
} */ *ap;
{
struct union_node *un = VTOUNION(ap->a_vp);
struct vnode *tvp;
int mode = ap->a_mode;
struct ucred *cred = ap->a_cred;
struct proc *p = ap->a_p;
int error = 0;
int tvpisupper = 1;
/*
* If there is an existing upper vp then simply open that.
* The upper vp takes precedence over the lower vp. When opening
* a lower vp for writing copy it to the uppervp and then open the
* uppervp.
*
* At the end of this section tvp will be left locked.
*/
if ((tvp = union_lock_upper(un, p)) == NULLVP) {
/*
* If the lower vnode is being opened for writing, then
* copy the file contents to the upper vnode and open that,
* otherwise can simply open the lower vnode.
*/
tvp = un->un_lowervp;
if ((ap->a_mode & FWRITE) && (tvp->v_type == VREG)) {
int docopy = !(mode & O_TRUNC);
error = union_copyup(un, docopy, cred, p);
tvp = union_lock_upper(un, p);
} else {
un->un_openl++;
VREF(tvp);
vn_lock(tvp, LK_EXCLUSIVE | LK_RETRY, p);
tvpisupper = 0;
}
}
/*
* We are holding the correct vnode, open it
*/
if (error == 0)
error = VOP_OPEN(tvp, mode, cred, p);
/*
* Absolutely necessary or UFS will blowup
*/
if (error == 0 && vn_canvmio(tvp) == TRUE) {
error = vfs_object_create(tvp, p, cred);
}
/*
* Release any locks held
*/
if (tvpisupper) {
if (tvp)
union_unlock_upper(tvp, p);
} else {
vput(tvp);
}
return (error);
}
/*
* union_close:
*
* It is unclear whether a_vp is passed locked or unlocked. Whatever
* the case we do not change it.
*/
static int
union_close(ap)
struct vop_close_args /* {
struct vnode *a_vp;
int a_fflag;
struct ucred *a_cred;
struct proc *a_p;
} */ *ap;
{
struct union_node *un = VTOUNION(ap->a_vp);
struct vnode *vp;
if ((vp = un->un_uppervp) == NULLVP) {
#ifdef UNION_DIAGNOSTIC
if (un->un_openl <= 0)
panic("union: un_openl cnt");
#endif
--un->un_openl;
vp = un->un_lowervp;
}
ap->a_vp = vp;
return (VCALL(vp, VOFFSET(vop_close), ap));
}
/*
* Check access permission on the union vnode.
* The access check being enforced is to check
* against both the underlying vnode, and any
* copied vnode. This ensures that no additional
* file permissions are given away simply because
* the user caused an implicit file copy.
*/
static int
union_access(ap)
struct vop_access_args /* {
struct vnodeop_desc *a_desc;
struct vnode *a_vp;
int a_mode;
struct ucred *a_cred;
struct proc *a_p;
} */ *ap;
{
struct union_node *un = VTOUNION(ap->a_vp);
struct proc *p = ap->a_p;
int error = EACCES;
struct vnode *vp;
/*
* Disallow write attempts on filesystems mounted read-only.
*/
if ((ap->a_mode & VWRITE) &&
(ap->a_vp->v_mount->mnt_flag & MNT_RDONLY)) {
switch (ap->a_vp->v_type) {
case VREG:
case VDIR:
case VLNK:
return (EROFS);
default:
break;
}
}
if ((vp = union_lock_upper(un, p)) != NULLVP) {
ap->a_vp = vp;
error = VCALL(vp, VOFFSET(vop_access), ap);
union_unlock_upper(vp, p);
return(error);
}
if ((vp = un->un_lowervp) != NULLVP) {
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p);
ap->a_vp = vp;
/*
* Remove VWRITE from a_mode if our mount point is RW, because
* we want to allow writes and lowervp may be read-only.
*/
if ((un->un_vnode->v_mount->mnt_flag & MNT_RDONLY) == 0)
ap->a_mode &= ~VWRITE;
error = VCALL(vp, VOFFSET(vop_access), ap);
if (error == 0) {
struct union_mount *um;
um = MOUNTTOUNIONMOUNT(un->un_vnode->v_mount);
if (um->um_op == UNMNT_BELOW) {
ap->a_cred = um->um_cred;
error = VCALL(vp, VOFFSET(vop_access), ap);
}
}
VOP_UNLOCK(vp, 0, p);
}
return(error);
}
/*
* We handle getattr only to change the fsid and
* track object sizes
*
* It's not clear whether VOP_GETATTR is to be
* called with the vnode locked or not. stat() calls
* it with (vp) locked, and fstat calls it with
* (vp) unlocked.
*
* Because of this we cannot use our normal locking functions
* if we do not intend to lock the main a_vp node. At the moment
* we are running without any specific locking at all, but beware
* to any programmer that care must be taken if locking is added
* to this function.
*/
static int
union_getattr(ap)
struct vop_getattr_args /* {
struct vnode *a_vp;
struct vattr *a_vap;
struct ucred *a_cred;
struct proc *a_p;
} */ *ap;
{
int error;
struct union_node *un = VTOUNION(ap->a_vp);
struct vnode *vp;
struct vattr *vap;
struct vattr va;
/*
* Some programs walk the filesystem hierarchy by counting
* links to directories to avoid stat'ing all the time.
* This means the link count on directories needs to be "correct".
* The only way to do that is to call getattr on both layers
* and fix up the link count. The link count will not necessarily
* be accurate but will be large enough to defeat the tree walkers.
*/
vap = ap->a_vap;
if ((vp = un->un_uppervp) != NULLVP) {
error = VOP_GETATTR(vp, vap, ap->a_cred, ap->a_p);
if (error)
return (error);
/* XXX isn't this dangerouso without a lock? */
union_newsize(ap->a_vp, vap->va_size, VNOVAL);
}
if (vp == NULLVP) {
vp = un->un_lowervp;
} else if (vp->v_type == VDIR && un->un_lowervp != NULLVP) {
vp = un->un_lowervp;
vap = &va;
} else {
vp = NULLVP;
}
if (vp != NULLVP) {
error = VOP_GETATTR(vp, vap, ap->a_cred, ap->a_p);
if (error)
return (error);
/* XXX isn't this dangerous without a lock? */
union_newsize(ap->a_vp, VNOVAL, vap->va_size);
}
if ((vap != ap->a_vap) && (vap->va_type == VDIR))
ap->a_vap->va_nlink += vap->va_nlink;
return (0);
}
static int
union_setattr(ap)
struct vop_setattr_args /* {
struct vnode *a_vp;
struct vattr *a_vap;
struct ucred *a_cred;
struct proc *a_p;
} */ *ap;
{
struct union_node *un = VTOUNION(ap->a_vp);
struct proc *p = ap->a_p;
struct vattr *vap = ap->a_vap;
struct vnode *uppervp;
int error;
/*
* Disallow write attempts on filesystems mounted read-only.
*/
if ((ap->a_vp->v_mount->mnt_flag & MNT_RDONLY) &&
(vap->va_flags != VNOVAL || vap->va_uid != (uid_t)VNOVAL ||
vap->va_gid != (gid_t)VNOVAL || vap->va_atime.tv_sec != VNOVAL ||
vap->va_mtime.tv_sec != VNOVAL ||
vap->va_mode != (mode_t)VNOVAL)) {
return (EROFS);
}
/*
* Handle case of truncating lower object to zero size,
* by creating a zero length upper object. This is to
* handle the case of open with O_TRUNC and O_CREAT.
*/
if (un->un_uppervp == NULLVP && (un->un_lowervp->v_type == VREG)) {
error = union_copyup(un, (ap->a_vap->va_size != 0),
ap->a_cred, ap->a_p);
if (error)
return (error);
}
/*
* Try to set attributes in upper layer,
* otherwise return read-only filesystem error.
*/
error = EROFS;
if ((uppervp = union_lock_upper(un, p)) != NULLVP) {
error = VOP_SETATTR(un->un_uppervp, ap->a_vap,
ap->a_cred, ap->a_p);
if ((error == 0) && (ap->a_vap->va_size != VNOVAL))
union_newsize(ap->a_vp, ap->a_vap->va_size, VNOVAL);
union_unlock_upper(uppervp, p);
}
return (error);
}
/*
* union_getpages:
*/
static int
union_getpages(struct vop_getpages_args *ap)
{
int r;
r = vnode_pager_generic_getpages(ap->a_vp, ap->a_m,
ap->a_count, ap->a_reqpage);
return(r);
}
/*
* union_putpages:
*/
static int
union_putpages(struct vop_putpages_args *ap)
{
int r;
r = vnode_pager_generic_putpages(ap->a_vp, ap->a_m, ap->a_count,
ap->a_sync, ap->a_rtvals);
return(r);
}
static int
union_read(ap)
struct vop_read_args /* {
struct vnode *a_vp;
struct uio *a_uio;
int a_ioflag;
struct ucred *a_cred;
} */ *ap;
{
struct union_node *un = VTOUNION(ap->a_vp);
struct proc *p = ap->a_uio->uio_procp;
struct vnode *uvp;
int error;
uvp = union_lock_other(un, p);
KASSERT(uvp != NULL, ("union_read: backing vnode missing!"));
if (ap->a_vp->v_flag & VOBJBUF)
union_vm_coherency(ap->a_vp, ap->a_uio, 0);
error = VOP_READ(uvp, ap->a_uio, ap->a_ioflag, ap->a_cred);
union_unlock_other(uvp, p);
/*
* XXX
* perhaps the size of the underlying object has changed under
* our feet. take advantage of the offset information present
* in the uio structure.
*/
if (error == 0) {
struct union_node *un = VTOUNION(ap->a_vp);
off_t cur = ap->a_uio->uio_offset;
if (uvp == un->un_uppervp) {
if (cur > un->un_uppersz)
union_newsize(ap->a_vp, cur, VNOVAL);
} else {
if (cur > un->un_lowersz)
union_newsize(ap->a_vp, VNOVAL, cur);
}
}
return (error);
}
static int
union_write(ap)
struct vop_read_args /* {
struct vnode *a_vp;
struct uio *a_uio;
int a_ioflag;
struct ucred *a_cred;
} */ *ap;
{
struct union_node *un = VTOUNION(ap->a_vp);
struct proc *p = ap->a_uio->uio_procp;
struct vnode *uppervp;
int error;
if ((uppervp = union_lock_upper(un, p)) == NULLVP)
panic("union: missing upper layer in write");
/*
* Since our VM pages are associated with our vnode rather then
* the real vnode, and since we do not run our reads and writes
* through our own VM cache, we have a VM/VFS coherency problem.
* We solve them by invalidating or flushing the associated VM
* pages prior to allowing a normal read or write to occur.
*
* VM-backed writes (UIO_NOCOPY) have to be converted to normal
* writes because we are not cache-coherent. Normal writes need
* to be made coherent with our VM-backing store, which we do by
* first flushing any dirty VM pages associated with the write
* range, and then destroying any clean VM pages associated with
* the write range.
*/
if (ap->a_uio->uio_segflg == UIO_NOCOPY) {
ap->a_uio->uio_segflg = UIO_SYSSPACE;
} else if (ap->a_vp->v_flag & VOBJBUF) {
union_vm_coherency(ap->a_vp, ap->a_uio, 1);
}
error = VOP_WRITE(uppervp, ap->a_uio, ap->a_ioflag, ap->a_cred);
/*
* the size of the underlying object may be changed by the
* write.
*/
if (error == 0) {
off_t cur = ap->a_uio->uio_offset;
if (cur > un->un_uppersz)
union_newsize(ap->a_vp, cur, VNOVAL);
}
union_unlock_upper(uppervp, p);
return (error);
}
static int
union_lease(ap)
struct vop_lease_args /* {
struct vnode *a_vp;
struct proc *a_p;
struct ucred *a_cred;
int a_flag;
} */ *ap;
{
struct vnode *ovp = OTHERVP(ap->a_vp);
ap->a_vp = ovp;
return (VCALL(ovp, VOFFSET(vop_lease), ap));
}
static int
union_ioctl(ap)
struct vop_ioctl_args /* {
struct vnode *a_vp;
int a_command;
caddr_t a_data;
int a_fflag;
struct ucred *a_cred;
struct proc *a_p;
} */ *ap;
{
struct vnode *ovp = OTHERVP(ap->a_vp);
ap->a_vp = ovp;
return (VCALL(ovp, VOFFSET(vop_ioctl), ap));
}
static int
union_poll(ap)
struct vop_poll_args /* {
struct vnode *a_vp;
int a_events;
struct ucred *a_cred;
struct proc *a_p;
} */ *ap;
{
struct vnode *ovp = OTHERVP(ap->a_vp);
ap->a_vp = ovp;
return (VCALL(ovp, VOFFSET(vop_poll), ap));
}
static int
union_revoke(ap)
struct vop_revoke_args /* {
struct vnode *a_vp;
int a_flags;
struct proc *a_p;
} */ *ap;
{
struct vnode *vp = ap->a_vp;
if (UPPERVP(vp))
VOP_REVOKE(UPPERVP(vp), ap->a_flags);
if (LOWERVP(vp))
VOP_REVOKE(LOWERVP(vp), ap->a_flags);
vgone(vp);
return (0);
}
static int
union_mmap(ap)
struct vop_mmap_args /* {
struct vnode *a_vp;
int a_fflags;
struct ucred *a_cred;
struct proc *a_p;
} */ *ap;
{
struct vnode *ovp = OTHERVP(ap->a_vp);
ap->a_vp = ovp;
return (VCALL(ovp, VOFFSET(vop_mmap), ap));
}
static int
union_fsync(ap)
struct vop_fsync_args /* {
struct vnode *a_vp;
struct ucred *a_cred;
int a_waitfor;
struct proc *a_p;
} */ *ap;
{
int error = 0;
struct proc *p = ap->a_p;
struct vnode *targetvp;
struct union_node *un = VTOUNION(ap->a_vp);
if ((targetvp = union_lock_other(un, p)) != NULLVP) {
error = VOP_FSYNC(targetvp, ap->a_cred, ap->a_waitfor, p);
union_unlock_other(targetvp, p);
}
return (error);
}
/*
* union_remove:
*
* Remove the specified cnp. The dvp and vp are passed to us locked
* and must remain locked on return.
*/
static int
union_remove(ap)
struct vop_remove_args /* {
struct vnode *a_dvp;
struct vnode *a_vp;
struct componentname *a_cnp;
} */ *ap;
{
struct union_node *dun = VTOUNION(ap->a_dvp);
struct union_node *un = VTOUNION(ap->a_vp);
struct componentname *cnp = ap->a_cnp;
struct proc *p = cnp->cn_proc;
struct vnode *uppervp;
struct vnode *upperdvp;
int error;
if ((upperdvp = union_lock_upper(dun, p)) == NULLVP)
panic("union remove: null upper vnode");
if ((uppervp = union_lock_upper(un, p)) != NULLVP) {
if (union_dowhiteout(un, cnp->cn_cred, p))
cnp->cn_flags |= DOWHITEOUT;
error = VOP_REMOVE(upperdvp, uppervp, cnp);
#if 0
/* XXX */
if (!error)
union_removed_upper(un);
#endif
union_unlock_upper(uppervp, p);
} else {
error = union_mkwhiteout(
MOUNTTOUNIONMOUNT(ap->a_dvp->v_mount),
upperdvp, ap->a_cnp, un->un_path);
}
union_unlock_upper(upperdvp, p);
return (error);
}
/*
* union_link:
*
* tdvp will be locked on entry, vp will not be locked on entry.
* tdvp should remain locked on return and vp should remain unlocked
* on return.
*/
static int
union_link(ap)
struct vop_link_args /* {
struct vnode *a_tdvp;
struct vnode *a_vp;
struct componentname *a_cnp;
} */ *ap;
{
struct componentname *cnp = ap->a_cnp;
struct proc *p = cnp->cn_proc;
struct union_node *dun = VTOUNION(ap->a_tdvp);
struct vnode *vp;
struct vnode *tdvp;
int error = 0;
if (ap->a_tdvp->v_op != ap->a_vp->v_op) {
vp = ap->a_vp;
} else {
struct union_node *tun = VTOUNION(ap->a_vp);
if (tun->un_uppervp == NULLVP) {
vn_lock(ap->a_vp, LK_EXCLUSIVE | LK_RETRY, p);
#if 0
if (dun->un_uppervp == tun->un_dirvp) {
if (dun->un_flags & UN_ULOCK) {
dun->un_flags &= ~UN_ULOCK;
VOP_UNLOCK(dun->un_uppervp, 0, p);
}
}
#endif
error = union_copyup(tun, 1, cnp->cn_cred, p);
#if 0
if (dun->un_uppervp == tun->un_dirvp) {
vn_lock(dun->un_uppervp,
LK_EXCLUSIVE | LK_RETRY, p);
dun->un_flags |= UN_ULOCK;
}
#endif
VOP_UNLOCK(ap->a_vp, 0, p);
}
vp = tun->un_uppervp;
}
if (error)
return (error);
/*
* Make sure upper is locked, then unlock the union directory we were
* called with to avoid a deadlock while we are calling VOP_LINK on
* the upper (with tdvp locked and vp not locked). Our ap->a_tdvp
* is expected to be locked on return.
*/
if ((tdvp = union_lock_upper(dun, p)) == NULLVP)
return (EROFS);
VOP_UNLOCK(ap->a_tdvp, 0, p); /* unlock calling node */
error = VOP_LINK(tdvp, vp, cnp); /* call link on upper */
/*
* We have to unlock tdvp prior to relocking our calling node in
* order to avoid a deadlock.
*/
union_unlock_upper(tdvp, p);
vn_lock(ap->a_tdvp, LK_EXCLUSIVE | LK_RETRY, p);
return (error);
}
static int
union_rename(ap)
struct vop_rename_args /* {
struct vnode *a_fdvp;
struct vnode *a_fvp;
struct componentname *a_fcnp;
struct vnode *a_tdvp;
struct vnode *a_tvp;
struct componentname *a_tcnp;
} */ *ap;
{
int error;
struct vnode *fdvp = ap->a_fdvp;
struct vnode *fvp = ap->a_fvp;
struct vnode *tdvp = ap->a_tdvp;
struct vnode *tvp = ap->a_tvp;
/*
* Figure out what fdvp to pass to our upper or lower vnode. If we
* replace the fdvp, release the original one and ref the new one.
*/
if (fdvp->v_op == union_vnodeop_p) { /* always true */
struct union_node *un = VTOUNION(fdvp);
if (un->un_uppervp == NULLVP) {
/*
* this should never happen in normal
* operation but might if there was
* a problem creating the top-level shadow
* directory.
*/
error = EXDEV;
goto bad;
}
fdvp = un->un_uppervp;
VREF(fdvp);
vrele(ap->a_fdvp);
}
/*
* Figure out what fvp to pass to our upper or lower vnode. If we
* replace the fvp, release the original one and ref the new one.
*/
if (fvp->v_op == union_vnodeop_p) { /* always true */
struct union_node *un = VTOUNION(fvp);
#if 0
struct union_mount *um = MOUNTTOUNIONMOUNT(fvp->v_mount);
#endif
if (un->un_uppervp == NULLVP) {
switch(fvp->v_type) {
case VREG:
vn_lock(un->un_vnode, LK_EXCLUSIVE | LK_RETRY, ap->a_fcnp->cn_proc);
error = union_copyup(un, 1, ap->a_fcnp->cn_cred, ap->a_fcnp->cn_proc);
VOP_UNLOCK(un->un_vnode, 0, ap->a_fcnp->cn_proc);
if (error)
goto bad;
break;
case VDIR:
/*
* XXX not yet.
*
* There is only one way to rename a directory
* based in the lowervp, and that is to copy
* the entire directory hierarchy. Otherwise
* it would not last across a reboot.
*/
#if 0
vrele(fvp);
fvp = NULL;
vn_lock(fdvp, LK_EXCLUSIVE | LK_RETRY, ap->a_fcnp->cn_proc);
error = union_mkshadow(um, fdvp,
ap->a_fcnp, &un->un_uppervp);
VOP_UNLOCK(fdvp, 0, ap->a_fcnp->cn_proc);
if (un->un_uppervp)
VOP_UNLOCK(un->un_uppervp, 0, ap->a_fcnp->cn_proc);
if (error)
goto bad;
break;
#endif
default:
error = EXDEV;
goto bad;
}
}
if (un->un_lowervp != NULLVP)
ap->a_fcnp->cn_flags |= DOWHITEOUT;
fvp = un->un_uppervp;
VREF(fvp);
vrele(ap->a_fvp);
}
/*
* Figure out what tdvp (destination directory) to pass to the
* lower level. If we replace it with uppervp, we need to vput the
* old one. The exclusive lock is transfered to what we will pass
* down in the VOP_RENAME and we replace uppervp with a simple
* reference.
*/
if (tdvp->v_op == union_vnodeop_p) {
struct union_node *un = VTOUNION(tdvp);
if (un->un_uppervp == NULLVP) {
/*
* this should never happen in normal
* operation but might if there was
* a problem creating the top-level shadow
* directory.
*/
error = EXDEV;
goto bad;
}
/*
* new tdvp is a lock and reference on uppervp, put away
* the old tdvp.
*/
tdvp = union_lock_upper(un, ap->a_tcnp->cn_proc);
vput(ap->a_tdvp);
}
/*
* Figure out what tvp (destination file) to pass to the
* lower level.
*
* If the uppervp file does not exist put away the (wrong)
* file and change tvp to NULL.
*/
if (tvp != NULLVP && tvp->v_op == union_vnodeop_p) {
struct union_node *un = VTOUNION(tvp);
tvp = union_lock_upper(un, ap->a_tcnp->cn_proc);
vput(ap->a_tvp);
/* note: tvp may be NULL */
}
/*
* VOP_RENAME releases/vputs prior to returning, so we have no
* cleanup to do.
*/
return (VOP_RENAME(fdvp, fvp, ap->a_fcnp, tdvp, tvp, ap->a_tcnp));
/*
* Error. We still have to release / vput the various elements.
*/
bad:
vrele(fdvp);
if (fvp)
vrele(fvp);
vput(tdvp);
if (tvp != NULLVP) {
if (tvp != tdvp)
vput(tvp);
else
vrele(tvp);
}
return (error);
}
static int
union_mkdir(ap)
struct vop_mkdir_args /* {
struct vnode *a_dvp;
struct vnode **a_vpp;
struct componentname *a_cnp;
struct vattr *a_vap;
} */ *ap;
{
struct union_node *dun = VTOUNION(ap->a_dvp);
struct componentname *cnp = ap->a_cnp;
struct proc *p = cnp->cn_proc;
struct vnode *upperdvp;
int error = EROFS;
if ((upperdvp = union_lock_upper(dun, p)) != NULLVP) {
struct vnode *vp;
error = VOP_MKDIR(upperdvp, &vp, cnp, ap->a_vap);
union_unlock_upper(upperdvp, p);
if (error == 0) {
VOP_UNLOCK(vp, 0, p);
UDEBUG(("ALLOCVP-2 FROM %p REFS %d\n", vp, vp->v_usecount));
error = union_allocvp(ap->a_vpp, ap->a_dvp->v_mount,
ap->a_dvp, NULLVP, cnp, vp, NULLVP, 1);
UDEBUG(("ALLOCVP-2B FROM %p REFS %d\n", *ap->a_vpp, vp->v_usecount));
}
}
return (error);
}
static int
union_rmdir(ap)
struct vop_rmdir_args /* {
struct vnode *a_dvp;
struct vnode *a_vp;
struct componentname *a_cnp;
} */ *ap;
{
struct union_node *dun = VTOUNION(ap->a_dvp);
struct union_node *un = VTOUNION(ap->a_vp);
struct componentname *cnp = ap->a_cnp;
struct proc *p = cnp->cn_proc;
struct vnode *upperdvp;
struct vnode *uppervp;
int error;
if ((upperdvp = union_lock_upper(dun, p)) == NULLVP)
panic("union rmdir: null upper vnode");
if ((uppervp = union_lock_upper(un, p)) != NULLVP) {
if (union_dowhiteout(un, cnp->cn_cred, p))
cnp->cn_flags |= DOWHITEOUT;
error = VOP_RMDIR(upperdvp, uppervp, ap->a_cnp);
union_unlock_upper(uppervp, p);
} else {
error = union_mkwhiteout(
MOUNTTOUNIONMOUNT(ap->a_dvp->v_mount),
dun->un_uppervp, ap->a_cnp, un->un_path);
}
union_unlock_upper(upperdvp, p);
return (error);
}
/*
* union_symlink:
*
* dvp is locked on entry and remains locked on return. a_vpp is garbage
* (unused).
*/
static int
union_symlink(ap)
struct vop_symlink_args /* {
struct vnode *a_dvp;
struct vnode **a_vpp;
struct componentname *a_cnp;
struct vattr *a_vap;
char *a_target;
} */ *ap;
{
struct union_node *dun = VTOUNION(ap->a_dvp);
struct componentname *cnp = ap->a_cnp;
struct proc *p = cnp->cn_proc;
struct vnode *dvp;
int error = EROFS;
if ((dvp = union_lock_upper(dun, p)) != NULLVP) {
error = VOP_SYMLINK(dvp, ap->a_vpp, cnp, ap->a_vap,
ap->a_target);
union_unlock_upper(dvp, p);
}
return (error);
}
/*
* union_readdir works in concert with getdirentries and
* readdir(3) to provide a list of entries in the unioned
* directories. getdirentries is responsible for walking
* down the union stack. readdir(3) is responsible for
* eliminating duplicate names from the returned data stream.
*/
static int
union_readdir(ap)
struct vop_readdir_args /* {
struct vnode *a_vp;
struct uio *a_uio;
struct ucred *a_cred;
int *a_eofflag;
u_long *a_cookies;
int a_ncookies;
} */ *ap;
{
struct union_node *un = VTOUNION(ap->a_vp);
struct proc *p = ap->a_uio->uio_procp;
struct vnode *uvp;
int error = 0;
if ((uvp = union_lock_upper(un, p)) != NULLVP) {
ap->a_vp = uvp;
error = VCALL(uvp, VOFFSET(vop_readdir), ap);
union_unlock_upper(uvp, p);
}
return(error);
}
static int
union_readlink(ap)
struct vop_readlink_args /* {
struct vnode *a_vp;
struct uio *a_uio;
struct ucred *a_cred;
} */ *ap;
{
int error;
struct union_node *un = VTOUNION(ap->a_vp);
struct uio *uio = ap->a_uio;
struct proc *p = uio->uio_procp;
struct vnode *vp;
vp = union_lock_other(un, p);
KASSERT(vp != NULL, ("union_readlink: backing vnode missing!"));
ap->a_vp = vp;
error = VCALL(vp, VOFFSET(vop_readlink), ap);
union_unlock_other(vp, p);
return (error);
}
static int
union_getwritemount(ap)
struct vop_getwritemount_args /* {
struct vnode *a_vp;
struct mount **a_mpp;
} */ *ap;
{
struct vnode *vp = UPPERVP(ap->a_vp);
if (vp == NULL)
panic("union: missing upper layer in getwritemount");
return(VOP_GETWRITEMOUNT(vp, ap->a_mpp));
}
/*
* union_inactive:
*
* Called with the vnode locked. We are expected to unlock the vnode.
*/
static int
union_inactive(ap)
struct vop_inactive_args /* {
struct vnode *a_vp;
struct proc *a_p;
} */ *ap;
{
struct vnode *vp = ap->a_vp;
struct proc *p = ap->a_p;
struct union_node *un = VTOUNION(vp);
struct vnode **vpp;
/*
* Do nothing (and _don't_ bypass).
* Wait to vrele lowervp until reclaim,
* so that until then our union_node is in the
* cache and reusable.
*
* NEEDSWORK: Someday, consider inactive'ing
* the lowervp and then trying to reactivate it
* with capabilities (v_id)
* like they do in the name lookup cache code.
* That's too much work for now.
*/
if (un->un_dircache != 0) {
for (vpp = un->un_dircache; *vpp != NULLVP; vpp++)
vrele(*vpp);
free (un->un_dircache, M_TEMP);
un->un_dircache = 0;
}
#if 0
if ((un->un_flags & UN_ULOCK) && un->un_uppervp) {
un->un_flags &= ~UN_ULOCK;
VOP_UNLOCK(un->un_uppervp, 0, p);
}
#endif
VOP_UNLOCK(vp, 0, p);
if ((un->un_flags & UN_CACHED) == 0)
vgone(vp);
return (0);
}
static int
union_reclaim(ap)
struct vop_reclaim_args /* {
struct vnode *a_vp;
} */ *ap;
{
union_freevp(ap->a_vp);
return (0);
}
static int
union_lock(ap)
struct vop_lock_args *ap;
{
#if 0
struct vnode *vp = ap->a_vp;
struct proc *p = ap->a_p;
int flags = ap->a_flags;
struct union_node *un;
#endif
int error;
error = vop_stdlock(ap);
#if 0
un = VTOUNION(vp);
if (error == 0) {
/*
* Lock the upper if it exists and this is an exclusive lock
* request.
*/
if (un->un_uppervp != NULLVP &&
(flags & LK_TYPE_MASK) == LK_EXCLUSIVE) {
if ((un->un_flags & UN_ULOCK) == 0 && vp->v_usecount) {
error = vn_lock(un->un_uppervp, flags, p);
if (error) {
struct vop_unlock_args uap = { 0 };
uap.a_vp = ap->a_vp;
uap.a_flags = ap->a_flags;
uap.a_p = ap->a_p;
vop_stdunlock(&uap);
return (error);
}
un->un_flags |= UN_ULOCK;
}
}
}
#endif
return (error);
}
/*
* union_unlock:
*
* Unlock our union node. This also unlocks uppervp.
*/
static int
union_unlock(ap)
struct vop_unlock_args /* {
struct vnode *a_vp;
int a_flags;
struct proc *a_p;
} */ *ap;
{
struct union_node *un = VTOUNION(ap->a_vp);
int error;
KASSERT((un->un_uppervp == NULL || un->un_uppervp->v_usecount > 0), ("uppervp usecount is 0"));
error = vop_stdunlock(ap);
#if 0
/*
* If no exclusive locks remain and we are holding an uppervp lock,
* remove the uppervp lock.
*/
if ((un->un_flags & UN_ULOCK) &&
lockstatus(&un->un_lock, NULL) != LK_EXCLUSIVE) {
un->un_flags &= ~UN_ULOCK;
VOP_UNLOCK(un->un_uppervp, LK_EXCLUSIVE, p);
}
#endif
return(error);
}
/*
* union_bmap:
*
* There isn't much we can do. We cannot push through to the real vnode
* to get to the underlying device because this will bypass data
* cached by the real vnode.
*
* For some reason we cannot return the 'real' vnode either, it seems
* to blow up memory maps.
*/
static int
union_bmap(ap)
struct vop_bmap_args /* {
struct vnode *a_vp;
daddr_t a_bn;
struct vnode **a_vpp;
daddr_t *a_bnp;
int *a_runp;
int *a_runb;
} */ *ap;
{
return(EOPNOTSUPP);
}
static int
union_print(ap)
struct vop_print_args /* {
struct vnode *a_vp;
} */ *ap;
{
struct vnode *vp = ap->a_vp;
printf("\ttag VT_UNION, vp=%p, uppervp=%p, lowervp=%p\n",
vp, UPPERVP(vp), LOWERVP(vp));
if (UPPERVP(vp) != NULLVP)
vprint("union: upper", UPPERVP(vp));
if (LOWERVP(vp) != NULLVP)
vprint("union: lower", LOWERVP(vp));
return (0);
}
static int
union_pathconf(ap)
struct vop_pathconf_args /* {
struct vnode *a_vp;
int a_name;
int *a_retval;
} */ *ap;
{
int error;
struct proc *p = curproc; /* XXX */
struct union_node *un = VTOUNION(ap->a_vp);
struct vnode *vp;
vp = union_lock_other(un, p);
KASSERT(vp != NULL, ("union_pathconf: backing vnode missing!"));
ap->a_vp = vp;
error = VCALL(vp, VOFFSET(vop_pathconf), ap);
union_unlock_other(vp, p);
return (error);
}
static int
union_advlock(ap)
struct vop_advlock_args /* {
struct vnode *a_vp;
caddr_t a_id;
int a_op;
struct flock *a_fl;
int a_flags;
} */ *ap;
{
register struct vnode *ovp = OTHERVP(ap->a_vp);
ap->a_vp = ovp;
return (VCALL(ovp, VOFFSET(vop_advlock), ap));
}
/*
* XXX - vop_strategy must be hand coded because it has no
* YYY - and it is not coherent with anything
*
* vnode in its arguments.
* This goes away with a merged VM/buffer cache.
*/
static int
union_strategy(ap)
struct vop_strategy_args /* {
struct vnode *a_vp;
struct buf *a_bp;
} */ *ap;
{
struct buf *bp = ap->a_bp;
struct vnode *othervp = OTHERVP(bp->b_vp);
#ifdef DIAGNOSTIC
if (othervp == NULLVP)
panic("union_strategy: nil vp");
if ((bp->b_iocmd == BIO_WRITE) &&
(othervp == LOWERVP(bp->b_vp)))
panic("union_strategy: writing to lowervp");
#endif
return (VOP_STRATEGY(othervp, bp));
}
/*
* Global vfs data structures
*/
vop_t **union_vnodeop_p;
static struct vnodeopv_entry_desc union_vnodeop_entries[] = {
{ &vop_default_desc, (vop_t *) vop_defaultop },
{ &vop_access_desc, (vop_t *) union_access },
{ &vop_advlock_desc, (vop_t *) union_advlock },
{ &vop_bmap_desc, (vop_t *) union_bmap },
{ &vop_close_desc, (vop_t *) union_close },
{ &vop_create_desc, (vop_t *) union_create },
{ &vop_fsync_desc, (vop_t *) union_fsync },
{ &vop_getpages_desc, (vop_t *) union_getpages },
{ &vop_putpages_desc, (vop_t *) union_putpages },
{ &vop_getattr_desc, (vop_t *) union_getattr },
{ &vop_inactive_desc, (vop_t *) union_inactive },
{ &vop_ioctl_desc, (vop_t *) union_ioctl },
{ &vop_islocked_desc, (vop_t *) vop_stdislocked },
{ &vop_lease_desc, (vop_t *) union_lease },
{ &vop_link_desc, (vop_t *) union_link },
{ &vop_lock_desc, (vop_t *) union_lock },
{ &vop_lookup_desc, (vop_t *) union_lookup },
{ &vop_mkdir_desc, (vop_t *) union_mkdir },
{ &vop_mknod_desc, (vop_t *) union_mknod },
{ &vop_mmap_desc, (vop_t *) union_mmap },
{ &vop_open_desc, (vop_t *) union_open },
{ &vop_pathconf_desc, (vop_t *) union_pathconf },
{ &vop_poll_desc, (vop_t *) union_poll },
{ &vop_print_desc, (vop_t *) union_print },
{ &vop_read_desc, (vop_t *) union_read },
{ &vop_readdir_desc, (vop_t *) union_readdir },
{ &vop_readlink_desc, (vop_t *) union_readlink },
{ &vop_getwritemount_desc, (vop_t *) union_getwritemount },
{ &vop_reclaim_desc, (vop_t *) union_reclaim },
{ &vop_remove_desc, (vop_t *) union_remove },
{ &vop_rename_desc, (vop_t *) union_rename },
{ &vop_revoke_desc, (vop_t *) union_revoke },
{ &vop_rmdir_desc, (vop_t *) union_rmdir },
{ &vop_setattr_desc, (vop_t *) union_setattr },
{ &vop_strategy_desc, (vop_t *) union_strategy },
{ &vop_symlink_desc, (vop_t *) union_symlink },
{ &vop_unlock_desc, (vop_t *) union_unlock },
{ &vop_whiteout_desc, (vop_t *) union_whiteout },
{ &vop_write_desc, (vop_t *) union_write },
{ NULL, NULL }
};
static struct vnodeopv_desc union_vnodeop_opv_desc =
{ &union_vnodeop_p, union_vnodeop_entries };
VNODEOP_SET(union_vnodeop_opv_desc);
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