int
union_root(struct mount *mp, struct vnode **vpp)
{
struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
int error;
/*
* Return locked reference to root.
*/
vref(um->um_uppervp);
if (um->um_lowervp)
vref(um->um_lowervp);
error = union_allocvp(vpp, mp, NULL, NULL, NULL,
um->um_uppervp, um->um_lowervp, 1);
if (error) {
vrele(um->um_uppervp);
if (um->um_lowervp)
vrele(um->um_lowervp);
return error;
}
vn_lock(*vpp, LK_EXCLUSIVE | LK_RETRY);
return 0;
}
/*
* 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.
*
* union_create(struct vnode *a_dvp, struct vnode **a_vpp,
* struct componentname *a_cnp, struct vattr *a_vap)
*/
static int
union_create(struct vop_old_create_args *ap)
{
struct union_node *dun = VTOUNION(ap->a_dvp);
struct componentname *cnp = ap->a_cnp;
struct thread *td = cnp->cn_td;
struct vnode *dvp;
int error = EROFS;
if ((dvp = union_lock_upper(dun, td)) != 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;
vn_unlock(vp);
UDEBUG(("ALLOCVP-1 FROM %p REFS %d\n", vp, vp->v_sysref.refcnt));
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_sysref.refcnt));
}
union_unlock_upper(dvp, td);
}
return (error);
}
/*
* union_mkdir(struct vnode *a_dvp, struct vnode **a_vpp,
* struct componentname *a_cnp, struct vattr *a_vap)
*/
static int
union_mkdir(struct vop_old_mkdir_args *ap)
{
struct union_node *dun = VTOUNION(ap->a_dvp);
struct componentname *cnp = ap->a_cnp;
struct thread *td = cnp->cn_td;
struct vnode *upperdvp;
int error = EROFS;
if ((upperdvp = union_lock_upper(dun, td)) != NULLVP) {
struct vnode *vp;
error = VOP_MKDIR(upperdvp, &vp, cnp, ap->a_vap);
union_unlock_upper(upperdvp, td);
if (error == 0) {
vn_unlock(vp);
UDEBUG(("ALLOCVP-2 FROM %p REFS %d\n", vp, vp->v_sysref.refcnt));
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_sysref.refcnt));
}
}
return (error);
}
/*
* union_lookup(struct vnode *a_dvp, struct vnode **a_vpp,
* struct componentname *a_cnp)
*/
static int
union_lookup(struct vop_old_lookup_args *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 thread *td = cnp->cn_td;
int lockparent = cnp->cn_flags & CNP_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 ((dvp->v_mount->mnt_flag & MNT_RDONLY) &&
(cnp->cn_nameiop == NAMEI_DELETE || cnp->cn_nameiop == NAMEI_RENAME)) {
return (EROFS);
}
/*
* For any lookup's we do, always return with the parent locked
*/
cnp->cn_flags |= CNP_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, td);
/*
* 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_sysref.refcnt,
vn_islocked(upperdvp),
uppervp,
(uppervp ? uppervp->v_sysref.refcnt : -99),
(uppervp ? vn_islocked(uppervp) : -99)
));
/*
* Disallow write attemps to the filesystem mounted read-only.
*/
if (uerror == EJUSTRETURN &&
(dvp->v_mount->mnt_flag & MNT_RDONLY) &&
(cnp->cn_nameiop == NAMEI_CREATE || cnp->cn_nameiop == NAMEI_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 & CNP_ISWHITEOUT) {
iswhiteout = 1;
} else if (lowerdvp != NULLVP) {
int terror;
terror = VOP_GETATTR(upperdvp, &va);
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 = NAMEI_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);
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 & CNP_ISDOTDOT) && dun->un_pvp != NULLVP) {
if ((lowervp = LOWERVP(dun->un_pvp)) != NULL) {
vref(lowervp);
vn_lock(lowervp, LK_EXCLUSIVE | LK_RETRY);
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)
vn_unlock(uppervp);
if (lowervp)
vn_unlock(lowervp);
if (upperdvp)
vn_unlock(upperdvp);
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_sysref.refcnt) : -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 &= ~CNP_LOCKPARENT;
UDEBUG(("Out %d vpp %p/%d lower %p upper %p\n", error, *ap->a_vpp,
((*ap->a_vpp) ? (*ap->a_vpp)->v_sysref.refcnt : -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) {
vn_unlock(dvp);
}
}
/*
* 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);
}
