Btrfs: Fix "no csum found for inode" issue.

A few codes were not properly updated for changes of extent map.  This
may be the causes of "no csum found for inode" issue.
Signed-off-by: NChris Mason <chris.mason@oracle.com>

fs/btrfs/extent_io.c

@@ -2417,12 +2417,13 @@ int try_release_extent_mapping(struct extent_map_tree *map,
 	u64 end = start + PAGE_CACHE_SIZE - 1;
 	u64 orig_start = start;
 	int ret = 1;
-
 	if ((mask & __GFP_WAIT) &&
 	    page->mapping->host->i_size > 16 * 1024 * 1024) {
+		u64 len;
 		while (start <= end) {
+			len = end - start + 1;
 			spin_lock(&map->lock);
-			em = lookup_extent_mapping(map, start, end);
+			em = lookup_extent_mapping(map, start, len);
 			if (!em || IS_ERR(em)) {
 				spin_unlock(&map->lock);
 				break;

fs/btrfs/file.c

@@ -357,10 +357,13 @@ int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end)
 {
 	struct extent_map *em;
 	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
+	u64 len = end - start + 1;
 
+	if (end == (u64)-1)
+		len = (u64)-1;
 	while(1) {
 		spin_lock(&em_tree->lock);
-		em = lookup_extent_mapping(em_tree, start, end);
+		em = lookup_extent_mapping(em_tree, start, len);
 		if (!em) {
 			spin_unlock(&em_tree->lock);
 			break;