btrfs: tree-checker: add extra ram_bytes and disk_num_bytes check

This is to ensure non-compressed file extents (both regular and
prealloc) should have matching ram_bytes and disk_num_bytes.

This is only for CONFIG_BTRFS_DEBUG and CONFIG_BTRFS_ASSERT case,
furthermore this will not return error, but just a kernel warning to
inform developers.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/tree-checker.c

@@ -340,6 +340,24 @@ static int check_extent_data_item(struct extent_buffer *leaf,
 		}
 	}
 
+	/*
+	 * For non-compressed data extents, ram_bytes should match its
+	 * disk_num_bytes.
+	 * However we do not really utilize ram_bytes in this case, so this check
+	 * is only optional for DEBUG builds for developers to catch the
+	 * unexpected behaviors.
+	 */
+	if (IS_ENABLED(CONFIG_BTRFS_DEBUG) &&
+	    btrfs_file_extent_compression(leaf, fi) == BTRFS_COMPRESS_NONE &&
+	    btrfs_file_extent_disk_bytenr(leaf, fi)) {
+		if (WARN_ON(btrfs_file_extent_ram_bytes(leaf, fi) !=
+			    btrfs_file_extent_disk_num_bytes(leaf, fi)))
+			file_extent_err(leaf, slot,
+"mismatch ram_bytes (%llu) and disk_num_bytes (%llu) for non-compressed extent",
+					btrfs_file_extent_ram_bytes(leaf, fi),
+					btrfs_file_extent_disk_num_bytes(leaf, fi));
+	}
+
 	return 0;
 }