ext4: annotate more implicit fall throughs

There is a plan to build the kernel with -Wimplicit-fallthrough and
these places in the code produced warnings (W=1). Fix them up.

This commit remove the following warnings:

  fs/ext4/indirect.c:1182:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
  fs/ext4/indirect.c:1188:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
  fs/ext4/indirect.c:1432:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
  fs/ext4/indirect.c:1440:6: warning: this statement may fall through [-Wimplicit-fallthrough=]

Signed-off-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>

fs/ext4/indirect.c

@@ -1183,18 +1183,21 @@ void ext4_ind_truncate(handle_t *handle, struct inode *inode)
 			ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
 			i_data[EXT4_IND_BLOCK] = 0;
 		}
+		/* fall through */
 	case EXT4_IND_BLOCK:
 		nr = i_data[EXT4_DIND_BLOCK];
 		if (nr) {
 			ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
 			i_data[EXT4_DIND_BLOCK] = 0;
 		}
+		/* fall through */
 	case EXT4_DIND_BLOCK:
 		nr = i_data[EXT4_TIND_BLOCK];
 		if (nr) {
 			ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
 			i_data[EXT4_TIND_BLOCK] = 0;
 		}
+		/* fall through */
 	case EXT4_TIND_BLOCK:
 		;
 	}
@@ -1433,6 +1436,7 @@ int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
 			ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
 			i_data[EXT4_IND_BLOCK] = 0;
 		}
+		/* fall through */
 	case EXT4_IND_BLOCK:
 		if (++n >= n2)
 			return 0;
@@ -1441,6 +1445,7 @@ int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
 			ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
 			i_data[EXT4_DIND_BLOCK] = 0;
 		}
+		/* fall through */
 	case EXT4_DIND_BLOCK:
 		if (++n >= n2)
 			return 0;
@@ -1449,6 +1454,7 @@ int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
 			ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
 			i_data[EXT4_TIND_BLOCK] = 0;
 		}
+		/* fall through */
 	case EXT4_TIND_BLOCK:
 		;
 	}