mm/vmalloc: use wrapper function get_vm_area_size to caculate size of vm area

Use wrapper function get_vm_area_size to calculate size of vm area.
Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/vmalloc.c

@@ -1258,7 +1258,7 @@ void unmap_kernel_range(unsigned long addr, unsigned long size)
 int map_vm_area(struct vm_struct *area, pgprot_t prot, struct page ***pages)
 {
 	unsigned long addr = (unsigned long)area->addr;
-	unsigned long end = addr + area->size - PAGE_SIZE;
+	unsigned long end = addr + get_vm_area_size(area);
 	int err;
 
 	err = vmap_page_range(addr, end, prot, *pages);
@@ -1553,7 +1553,7 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
 	unsigned int nr_pages, array_size, i;
 	gfp_t nested_gfp = (gfp_mask & GFP_RECLAIM_MASK) | __GFP_ZERO;
 
-	nr_pages = (area->size - PAGE_SIZE) >> PAGE_SHIFT;
+	nr_pages = get_vm_area_size(area) >> PAGE_SHIFT;
 	array_size = (nr_pages * sizeof(struct page *));
 
 	area->nr_pages = nr_pages;
@@ -1985,7 +1985,7 @@ long vread(char *buf, char *addr, unsigned long count)
 
 		vm = va->vm;
 		vaddr = (char *) vm->addr;
-		if (addr >= vaddr + vm->size - PAGE_SIZE)
+		if (addr >= vaddr + get_vm_area_size(vm))
 			continue;
 		while (addr < vaddr) {
 			if (count == 0)
@@ -1995,7 +1995,7 @@ long vread(char *buf, char *addr, unsigned long count)
 			addr++;
 			count--;
 		}
-		n = vaddr + vm->size - PAGE_SIZE - addr;
+		n = vaddr + get_vm_area_size(vm) - addr;
 		if (n > count)
 			n = count;
 		if (!(vm->flags & VM_IOREMAP))
@@ -2067,7 +2067,7 @@ long vwrite(char *buf, char *addr, unsigned long count)
 
 		vm = va->vm;
 		vaddr = (char *) vm->addr;
-		if (addr >= vaddr + vm->size - PAGE_SIZE)
+		if (addr >= vaddr + get_vm_area_size(vm))
 			continue;
 		while (addr < vaddr) {
 			if (count == 0)
@@ -2076,7 +2076,7 @@ long vwrite(char *buf, char *addr, unsigned long count)
 			addr++;
 			count--;
 		}
-		n = vaddr + vm->size - PAGE_SIZE - addr;
+		n = vaddr + get_vm_area_size(vm) - addr;
 		if (n > count)
 			n = count;
 		if (!(vm->flags & VM_IOREMAP)) {