mm: use vm_unmapped_area() in hugetlbfs on ia64 architecture

Update the ia64 hugetlb_get_unmapped_area function to make use of
vm_unmapped_area() instead of implementing a brute force search.
Signed-off-by: Michel Lespinasse <walken@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/mm/hugetlbpage.c

@@ -148,7 +148,7 @@ void hugetlb_free_pgd_range(struct mmu_gather *tlb,
 unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
 		unsigned long pgoff, unsigned long flags)
 {
-	struct vm_area_struct *vmm;
+	struct vm_unmapped_area_info info;
 
 	if (len > RGN_MAP_LIMIT)
 		return -ENOMEM;
@@ -165,16 +165,14 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr, u
 	/* This code assumes that RGN_HPAGE != 0. */
 	if ((REGION_NUMBER(addr) != RGN_HPAGE) || (addr & (HPAGE_SIZE - 1)))
 		addr = HPAGE_REGION_BASE;
-	else
-		addr = ALIGN(addr, HPAGE_SIZE);
-	for (vmm = find_vma(current->mm, addr); ; vmm = vmm->vm_next) {
-		/* At this point:  (!vmm || addr < vmm->vm_end). */
-		if (REGION_OFFSET(addr) + len > RGN_MAP_LIMIT)
-			return -ENOMEM;
-		if (!vmm || (addr + len) <= vmm->vm_start)
-			return addr;
-		addr = ALIGN(vmm->vm_end, HPAGE_SIZE);
-	}
+
+	info.flags = 0;
+	info.length = len;
+	info.low_limit = addr;
+	info.high_limit = HPAGE_REGION_BASE + RGN_MAP_LIMIT;
+	info.align_mask = PAGE_MASK & (HPAGE_SIZE - 1);
+	info.align_offset = 0;
+	return vm_unmapped_area(&info);
 }
 
 static int __init hugetlb_setup_sz(char *str)