/*
* We need to process our own vnode unlock and then clear the
* interlock flag as it applies only to our vnode, not the
* vnodes below us on the stack.
*/
static int
null_unlock(struct vop_unlock_args *ap)
{
struct vnode *vp = ap->a_vp;
int flags = ap->a_flags;
int mtxlkflag = 0;
struct null_node *nn;
struct vnode *lvp;
int error;
if ((flags & LK_INTERLOCK) != 0)
mtxlkflag = 1;
else if (mtx_owned(VI_MTX(vp)) == 0) {
VI_LOCK(vp);
mtxlkflag = 2;
}
nn = VTONULL(vp);
if (nn != NULL && (lvp = NULLVPTOLOWERVP(vp)) != NULL) {
VI_LOCK_FLAGS(lvp, MTX_DUPOK);
flags |= LK_INTERLOCK;
vholdl(lvp);
VI_UNLOCK(vp);
error = VOP_UNLOCK(lvp, flags);
vdrop(lvp);
if (mtxlkflag == 0)
VI_LOCK(vp);
} else {
if (mtxlkflag == 2)
VI_UNLOCK(vp);
error = vop_stdunlock(ap);
}
return (error);
}
int
osi_TryEvictVCache(struct vcache *avc, int *slept, int defersleep)
{
struct vnode *vp;
int code;
vp = AFSTOV(avc);
if (!VI_TRYLOCK(vp))
return 0;
code = osi_fbsd_checkinuse(avc);
if (code != 0) {
VI_UNLOCK(vp);
return 0;
}
if ((vp->v_iflag & VI_DOOMED) != 0) {
VI_UNLOCK(vp);
return 1;
}
/* must hold the vnode before calling vgone()
* This code largely copied from vfs_subr.c:vlrureclaim() */
vholdl(vp);
AFS_GUNLOCK();
*slept = 1;
/* use the interlock while locking, so no one else can DOOM this */
ma_vn_lock(vp, LK_INTERLOCK|LK_EXCLUSIVE|LK_RETRY, curthread);
vgone(vp);
MA_VOP_UNLOCK(vp, 0, curthread);
vdrop(vp);
AFS_GLOCK();
return 1;
}
/* Try to discard pages, in order to recycle a vcache entry.
*
* We also make some sanity checks: ref count, open count, held locks.
*
* We also do some non-VM-related chores, such as releasing the cred pointer
* (for AIX and Solaris) and releasing the gnode (for AIX).
*
* Locking: afs_xvcache lock is held. If it is dropped and re-acquired,
* *slept should be set to warn the caller.
*
* Formerly, afs_xvcache was dropped and re-acquired for Solaris, but now it
* is not dropped and re-acquired for any platform. It may be that *slept is
* therefore obsolescent.
*
*/
int
osi_VM_FlushVCache(struct vcache *avc, int *slept)
{
struct vnode *vp;
int code;
vp = AFSTOV(avc);
if (!VI_TRYLOCK(vp))
return EBUSY;
code = osi_fbsd_checkinuse(avc);
if (code) {
VI_UNLOCK(vp);
return code;
}
/* must hold the vnode before calling cache_purge()
* This code largely copied from vfs_subr.c:vlrureclaim() */
vholdl(vp);
VI_UNLOCK(vp);
AFS_GUNLOCK();
cache_purge(vp);
AFS_GLOCK();
vdrop(vp);
return 0;
}
/* Try to discard pages, in order to recycle a vcache entry.
*
* We also make some sanity checks: ref count, open count, held locks.
*
* We also do some non-VM-related chores, such as releasing the cred pointer
* (for AIX and Solaris) and releasing the gnode (for AIX).
*
* Locking: afs_xvcache lock is held. If it is dropped and re-acquired,
* *slept should be set to warn the caller.
*
* Formerly, afs_xvcache was dropped and re-acquired for Solaris, but now it
* is not dropped and re-acquired for any platform. It may be that *slept is
* therefore obsolescent.
*
*/
int
osi_VM_FlushVCache(struct vcache *avc, int *slept)
{
struct vm_object *obj;
struct vnode *vp = AFSTOV(avc);
if (!VI_TRYLOCK(vp)) /* need interlock to check usecount */
return EBUSY;
if (vp->v_usecount > 0) {
VI_UNLOCK(vp);
return EBUSY;
}
/* XXX
* The value of avc->opens here came to be, at some point,
* typically -1. This was caused by incorrectly performing afs_close
* processing on vnodes being recycled */
if (avc->opens) {
VI_UNLOCK(vp);
return EBUSY;
}
/* if a lock is held, give up */
if (CheckLock(&avc->lock)) {
VI_UNLOCK(vp);
return EBUSY;
}
if ((vp->v_iflag & VI_DOOMED) != 0) {
VI_UNLOCK(vp);
return (0);
}
/* must hold the vnode before calling vgone()
* This code largely copied from vfs_subr.c:vlrureclaim() */
vholdl(vp);
AFS_GUNLOCK();
*slept = 1;
/* use the interlock while locking, so no one else can DOOM this */
ilock_vnode(vp);
vgone(vp);
unlock_vnode(vp);
vdrop(vp);
AFS_GLOCK();
return 0;
}
/* ARGSUSED */
static int
null_getwritemount(struct vop_getwritemount_args *ap)
{
struct null_node *xp;
struct vnode *lowervp;
struct vnode *vp;
vp = ap->a_vp;
VI_LOCK(vp);
xp = VTONULL(vp);
if (xp && (lowervp = xp->null_lowervp)) {
VI_LOCK_FLAGS(lowervp, MTX_DUPOK);
VI_UNLOCK(vp);
vholdl(lowervp);
VI_UNLOCK(lowervp);
VOP_GETWRITEMOUNT(lowervp, ap->a_mpp);
vdrop(lowervp);
} else {
VI_UNLOCK(vp);
*(ap->a_mpp) = NULL;
}
return (0);
}
/*
* We need to process our own vnode lock and then clear the
* interlock flag as it applies only to our vnode, not the
* vnodes below us on the stack.
*/
static int
null_lock(struct vop_lock1_args *ap)
{
struct vnode *vp = ap->a_vp;
int flags = ap->a_flags;
struct null_node *nn;
struct vnode *lvp;
int error;
if ((flags & LK_INTERLOCK) == 0) {
VI_LOCK(vp);
ap->a_flags = flags |= LK_INTERLOCK;
}
nn = VTONULL(vp);
/*
* If we're still active we must ask the lower layer to
* lock as ffs has special lock considerations in it's
* vop lock.
*/
if (nn != NULL && (lvp = NULLVPTOLOWERVP(vp)) != NULL) {
VI_LOCK_FLAGS(lvp, MTX_DUPOK);
VI_UNLOCK(vp);
/*
* We have to hold the vnode here to solve a potential
* reclaim race. If we're forcibly vgone'd while we
* still have refs, a thread could be sleeping inside
* the lowervp's vop_lock routine. When we vgone we will
* drop our last ref to the lowervp, which would allow it
* to be reclaimed. The lowervp could then be recycled,
* in which case it is not legal to be sleeping in it's VOP.
* We prevent it from being recycled by holding the vnode
* here.
*/
vholdl(lvp);
error = VOP_LOCK(lvp, flags);
/*
* We might have slept to get the lock and someone might have
* clean our vnode already, switching vnode lock from one in
* lowervp to v_lock in our own vnode structure. Handle this
* case by reacquiring correct lock in requested mode.
*/
if (VTONULL(vp) == NULL && error == 0) {
ap->a_flags &= ~(LK_TYPE_MASK | LK_INTERLOCK);
switch (flags & LK_TYPE_MASK) {
case LK_SHARED:
ap->a_flags |= LK_SHARED;
break;
case LK_UPGRADE:
case LK_EXCLUSIVE:
ap->a_flags |= LK_EXCLUSIVE;
break;
default:
panic("Unsupported lock request %d\n",
ap->a_flags);
}
VOP_UNLOCK(lvp, 0);
error = vop_stdlock(ap);
}
vdrop(lvp);
} else
error = vop_stdlock(ap);
return (error);
}
