fs/squashfs: new filesystem

Add support for SquashFS filesystem. Right now, it does not support
compression but support for zlib will be added in a follow-up commit.

Signed-off-by: Joao Marcos Costa <joaomarcos.costa@bootlin.com>

1 files changed, 49 insertions, 0 deletions

diff --git a/fs/squashfs/sqfs_utils.h b/fs/squashfs/sqfs_utils.h
new file mode 100644
index 0000000..1260abe
--- /dev/null
+++ b/fs/squashfs/sqfs_utils.h
@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020 Bootlin
+ *
+ * Author: Joao Marcos Costa <joaomarcos.costa@bootlin.com>
+ */
+
+#ifndef SQFS_UTILS_H
+#define SQFS_UTILS_H
+
+#include <linux/bitops.h>
+#include <linux/kernel.h>
+#include <stdbool.h>
+
+#define SQFS_FRAGMENT_INDEX_OFFSET(A) ((A) % SQFS_MAX_ENTRIES)
+#define SQFS_FRAGMENT_INDEX(A) ((A) / SQFS_MAX_ENTRIES)
+#define SQFS_BLOCK_SIZE(A) ((A) & GENMASK(23, 0))
+#define SQFS_CHECK_FLAG(flag, bit) (((flag) >> (bit)) & 1)
+/* Useful for both fragment and data blocks */
+#define SQFS_COMPRESSED_BLOCK(A) (!((A) & BIT(24)))
+/* SQFS_COMPRESSED_DATA strictly used with super block's 'flags' member */
+#define SQFS_COMPRESSED_DATA(A) (!((A) & 0x0002))
+#define SQFS_IS_FRAGMENTED(A) ((A) != 0xFFFFFFFF)
+/*
+ * These two macros work as getters for a metada block header, retrieving the
+ * data size and if it is compressed/uncompressed
+ */
+#define SQFS_COMPRESSED_METADATA(A) (!((A) & BIT(15)))
+#define SQFS_METADATA_SIZE(A) ((A) & GENMASK(14, 0))
+
+struct squashfs_super_block_flags {
+	/* check: unused
+	 * uncompressed_ids: not supported
+	 */
+	bool uncompressed_inodes;
+	bool uncompressed_data;
+	bool check;
+	bool uncompressed_frags;
+	bool no_frags;
+	bool always_frags;
+	bool duplicates;
+	bool exportable;
+	bool uncompressed_xattrs;
+	bool no_xattrs;
+	bool compressor_options;
+	bool uncompressed_ids;
+};
+
+#endif /* SQFS_UTILS_H  */