/* Try to store pages to cache, in order to store a file back to the server.
*
* Locking: the vcache entry's lock is held. It will usually be dropped and
* re-obtained.
*/
void
osi_VM_StoreAllSegments(struct vcache *avc)
{
struct vnode *vp;
struct vm_object *obj;
int anyio, tries;
ReleaseWriteLock(&avc->lock);
AFS_GUNLOCK();
tries = 5;
vp = AFSTOV(avc);
/*
* I don't understand this. Why not just call vm_object_page_clean()
* and be done with it? I particularly don't understand why we're calling
* vget() here. Is there some reason to believe that the vnode might
* be being recycled at this point? I don't think there's any need for
* this loop, either -- if we keep the vnode locked all the time,
* that and the object lock will prevent any new pages from appearing.
* The loop is what causes the race condition. -GAW
*/
do {
anyio = 0;
if (VOP_GETVOBJECT(vp, &obj) == 0 && (obj->flags & OBJ_MIGHTBEDIRTY)) {
if (!vget(vp, LK_EXCLUSIVE | LK_RETRY, curthread)) {
if (VOP_GETVOBJECT(vp, &obj) == 0) {
VM_OBJECT_LOCK(obj);
vm_object_page_clean(obj, 0, 0, OBJPC_SYNC);
VM_OBJECT_UNLOCK(obj);
anyio = 1;
}
vput(vp);
}
}
} while (anyio && (--tries > 0));
AFS_GLOCK();
ObtainWriteLock(&avc->lock, 94);
}
/* Purge VM for a file when its callback is revoked.
*
* Locking: No lock is held, not even the global lock.
*/
void
osi_VM_FlushPages(struct vcache *avc, afs_ucred_t *credp)
{
struct vnode *vp;
struct vm_object *obj;
vp = AFSTOV(avc);
ASSERT_VOP_LOCKED(vp, __func__);
if (VOP_GETVOBJECT(vp, &obj) == 0) {
VM_OBJECT_LOCK(obj);
vm_object_page_remove(obj, 0, 0, FALSE);
VM_OBJECT_UNLOCK(obj);
}
osi_vinvalbuf(vp, 0, 0, 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.
*
* OSF/1 Locking: VN_LOCK has been called.
* We do not lock the vnode here, but instead require that it be exclusive
* locked by code calling osi_VM_StoreAllSegments directly, or scheduling it
* from the bqueue - Matt
* Maybe better to just call vnode_pager_setsize()?
*/
int
osi_VM_FlushVCache(struct vcache *avc, int *slept)
{
struct vm_object *obj;
struct vnode *vp;
if (VREFCOUNT(avc) > 1)
return EBUSY;
if (avc->opens)
return EBUSY;
/* if a lock is held, give up */
if (CheckLock(&avc->lock))
return EBUSY;
return(0);
AFS_GUNLOCK();
vp = AFSTOV(avc);
#ifndef AFS_FBSD70_ENV
lock_vnode(vp);
#endif
if (VOP_GETVOBJECT(vp, &obj) == 0) {
VM_OBJECT_LOCK(obj);
vm_object_page_remove(obj, 0, 0, FALSE);
#if 1
if (obj->ref_count == 0) {
simple_lock(&vp->v_interlock);
vgonel(vp, curthread);
vp->v_tag = VT_AFS;
SetAfsVnode(vp);
}
#endif
VM_OBJECT_UNLOCK(obj);
}
#ifndef AFS_FBSD70_ENV
unlock_vnode(vp);
#endif
AFS_GLOCK();
return 0;
}
