mm: add unmap_mapping_pages()

Several users of unmap_mapping_range() would prefer to express their
range in pages rather than bytes.  Unfortuately, on a 32-bit kernel, you
have to remember to cast your page number to a 64-bit type before
shifting it, and four places in the current tree didn't remember to do
that.  That's a sign of a bad interface.

Conveniently, unmap_mapping_range() actually converts from bytes into
pages, so hoist the guts of unmap_mapping_range() into a new function
unmap_mapping_pages() and convert the callers which want to use pages.

Link: http://lkml.kernel.org/r/20171206142627.GD32044@bombadil.infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Reported-by: "zhangyi (F)" <yi.zhang@huawei.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 16 deletions

diff --git a/mm/truncate.c b/mm/truncate.c
index e4b4cf0f4070..c34e2fd4f583 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -179,12 +179,8 @@ static void
 truncate_cleanup_page(struct address_space *mapping, struct page *page)
 {
 	if (page_mapped(page)) {
-		loff_t holelen;
-
-		holelen = PageTransHuge(page) ? HPAGE_PMD_SIZE : PAGE_SIZE;
-		unmap_mapping_range(mapping,
-				   (loff_t)page->index << PAGE_SHIFT,
-				   holelen, 0);
+		pgoff_t nr = PageTransHuge(page) ? HPAGE_PMD_NR : 1;
+		unmap_mapping_pages(mapping, page->index, nr, false);
 	}
 
 	if (page_has_private(page))
@@ -715,19 +711,15 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
 					/*
 					 * Zap the rest of the file in one hit.
 					 */
-					unmap_mapping_range(mapping,
-					   (loff_t)index << PAGE_SHIFT,
-					   (loff_t)(1 + end - index)
-							 << PAGE_SHIFT,
-							 0);
+					unmap_mapping_pages(mapping, index,
+						(1 + end - index), false);
 					did_range_unmap = 1;
 				} else {
 					/*
 					 * Just zap this page
 					 */
-					unmap_mapping_range(mapping,
-					   (loff_t)index << PAGE_SHIFT,
-					   PAGE_SIZE, 0);
+					unmap_mapping_pages(mapping, index,
+								1, false);
 				}
 			}
 			BUG_ON(page_mapped(page));
@@ -753,8 +745,7 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
 	 * get remapped later.
 	 */
 	if (dax_mapping(mapping)) {
-		unmap_mapping_range(mapping, (loff_t)start << PAGE_SHIFT,
-				    (loff_t)(end - start + 1) << PAGE_SHIFT, 0);
+		unmap_mapping_pages(mapping, start, end - start + 1, false);
 	}
 out:
 	cleancache_invalidate_inode(mapping);