reiserfs: use ->invalidatepage() length argument

->invalidatepage() aop now accepts range to invalidate so we can make
use of it in reiserfs_invalidatepage()
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Cc: reiserfs-devel@vger.kernel.org

fs/reiserfs/inode.c

@@ -2976,11 +2976,13 @@ static void reiserfs_invalidatepage(struct page *page, unsigned int offset,
 	struct buffer_head *head, *bh, *next;
 	struct inode *inode = page->mapping->host;
 	unsigned int curr_off = 0;
+	unsigned int stop = offset + length;
+	int partial_page = (offset || length < PAGE_CACHE_SIZE);
 	int ret = 1;
 
 	BUG_ON(!PageLocked(page));
 
-	if (offset == 0)
+	if (!partial_page)
 		ClearPageChecked(page);
 
 	if (!page_has_buffers(page))
@@ -2992,6 +2994,9 @@ static void reiserfs_invalidatepage(struct page *page, unsigned int offset,
 		unsigned int next_off = curr_off + bh->b_size;
 		next = bh->b_this_page;
 
+		if (next_off > stop)
+			goto out;
+
 		/*
 		 * is this block fully invalidated?
 		 */
@@ -3010,7 +3015,7 @@ static void reiserfs_invalidatepage(struct page *page, unsigned int offset,
 	 * The get_block cached value has been unconditionally invalidated,
 	 * so real IO is not possible anymore.
 	 */
-	if (!offset && ret) {
+	if (!partial_page && ret) {
 		ret = try_to_release_page(page, 0);
 		/* maybe should BUG_ON(!ret); - neilb */
 	}