Function vm_fault_soft_fast

freebsd/vm/vm_fault.c:297–368

* Unlocks fs.first_object and fs.map on success. */

 * Unlocks fs.first_object and fs.map on success.
 */
static int
vm_fault_soft_fast(struct faultstate *fs)
{
	vm_page_t m, m_map;
#if VM_NRESERVLEVEL > 0
	vm_page_t m_super;
	int flags;
#endif
	int psind, rv;
	vm_offset_t vaddr;

	MPASS(fs->vp == NULL);
	vaddr = fs->vaddr;
	vm_object_busy(fs->first_object);
	m = vm_page_lookup(fs->first_object, fs->first_pindex);
	/* A busy page can be mapped for read|execute access. */
	if (m == NULL || ((fs->prot & VM_PROT_WRITE) != 0 &&
	    vm_page_busied(m)) || !vm_page_all_valid(m)) {
		rv = KERN_FAILURE;
		goto out;
	}
	m_map = m;
	psind = 0;
#if VM_NRESERVLEVEL > 0
	if ((m->flags & PG_FICTITIOUS) == 0 &&
	    (m_super = vm_reserv_to_superpage(m)) != NULL &&
	    rounddown2(vaddr, pagesizes[m_super->psind]) >= fs->entry->start &&
	    roundup2(vaddr + 1, pagesizes[m_super->psind]) <= fs->entry->end &&
	    (vaddr & (pagesizes[m_super->psind] - 1)) == (VM_PAGE_TO_PHYS(m) &
	    (pagesizes[m_super->psind] - 1)) && !fs->wired &&
	    pmap_ps_enabled(fs->map->pmap)) {
		flags = PS_ALL_VALID;
		if ((fs->prot & VM_PROT_WRITE) != 0) {
			/*
			 * Create a superpage mapping allowing write access
			 * only if none of the constituent pages are busy and
			 * all of them are already dirty (except possibly for
			 * the page that was faulted on).
			 */
			flags |= PS_NONE_BUSY;
			if ((fs->first_object->flags & OBJ_UNMANAGED) == 0)
				flags |= PS_ALL_DIRTY;
		}
		if (vm_page_ps_test(m_super, flags, m)) {
			m_map = m_super;
			psind = m_super->psind;
			vaddr = rounddown2(vaddr, pagesizes[psind]);
			/* Preset the modified bit for dirty superpages. */
			if ((flags & PS_ALL_DIRTY) != 0)
				fs->fault_type |= VM_PROT_WRITE;
		}
	}
#endif
	rv = pmap_enter(fs->map->pmap, vaddr, m_map, fs->prot, fs->fault_type |
	    PMAP_ENTER_NOSLEEP | (fs->wired ? PMAP_ENTER_WIRED : 0), psind);
	if (rv != KERN_SUCCESS)
		goto out;
	if (fs->m_hold != NULL) {