[U-Boot,5/9] fs: btrfs: Add disk-to-cpu and cpu-to-disk conversion functions

diff --git a/fs/btrfs/conv-funcs.h b/fs/btrfs/conv-funcs.h
new file mode 100644
index 0000000000..f2e7944e4e
--- /dev/null
+++ b/fs/btrfs/conv-funcs.h
@@ -0,0 +1,176 @@ 
+/*
+ * Functions to convert BTRFS structures from disk to CPU endianness and back.
+ *
+ * 2017 Marek Behun, CZ.NIC, marek.behun@nic.cz
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef __BTRFS_CONV_FUNCS_H__
+#define __BTRFS_CONV_FUNCS_H__
+
+#include "ctree.h"
+#include <u-boot/variadic-macro.h>
+#include <asm/byteorder.h>
+
+/* We are using variadic macros and C11 _Generic to achieve compact code.
+
+   We want to define macro DEFINE_CONV(x, ...), where the first argument is the
+   name of the structure for which it shall define conversion functions (the
+   names of the functions shall be x_to_cpu and x_to_disk), and the other
+   arguments are names of the members on which the functions shall do
+   endianness conversion. */
+
+#if defined(__LITTLE_ENDIAN)
+
+/* If the target machine is little endian, the conversion functions do
+   nothing, since the on disk format is little endian. */
+
+# define DEFINE_CONV(n,...)					\
+	static inline struct n *n##_to_disk(struct n * r)	\
+	{							\
+		return r;					\
+	}							\
+	static inline struct n *n##_to_cpu(struct n * r)	\
+	{							\
+		return r;					\
+	}
+
+# define DEFINE_CONV_ALT(n,a,...)				\
+	static inline struct n *n##_to_disk_##a(struct n * r)	\
+	{							\
+		return r;					\
+	}							\
+	static inline struct n *n##_to_cpu_##a(struct n * r)	\
+	{							\
+		return r;					\
+	}
+
+#else /* !defined(__LITTLE_ENDIAN) */
+
+/* Some structures contain not only scalar members, but compound types as well
+   (for example, struct btrfs_inode_item contains members of type struct
+   btrfs_timespec.
+
+   For these members we want to call the conversion function recursively, so
+   first we declare the functions taking pointers to this types (these function
+   will be defined later by the DEFINE_CONV macro) and then we define
+   correspond functions taking non-pointers, so that they can be used in the
+   expansion of the _Generic. */
+# define DEFINE_CONV_FOR_STRUCT(n)				\
+	static inline struct n * n##_to_disk(struct n *);	\
+	static inline struct n * n##_to_cpu(struct n *);	\
+	static inline struct n n##_to_disk_v(struct n x) {	\
+		return *n##_to_disk(&x);			\
+	}							\
+	static inline struct n n##_to_cpu_v(struct n x) {	\
+		return *n##_to_cpu(&x);				\
+	}
+
+DEFINE_CONV_FOR_STRUCT(btrfs_key)
+DEFINE_CONV_FOR_STRUCT(btrfs_stripe)
+DEFINE_CONV_FOR_STRUCT(btrfs_timespec)
+DEFINE_CONV_FOR_STRUCT(btrfs_inode_item)
+DEFINE_CONV_FOR_STRUCT(btrfs_root_backup)
+DEFINE_CONV_FOR_STRUCT(btrfs_dev_item)
+
+/* Now define the _Generic for both CPU to LE and LE to CPU */
+# define DEFINE_CONV_CPU_TO_LE(x)					\
+	(d->x) = _Generic((d->x),					\
+		__u16: cpu_to_le16,					\
+		__u32: cpu_to_le32,					\
+		__u64: cpu_to_le64,					\
+		struct btrfs_key: btrfs_key_to_disk_v,			\
+		struct btrfs_stripe: btrfs_stripe_to_disk_v,		\
+		struct btrfs_timespec: btrfs_timespec_to_disk_v,	\
+		struct btrfs_inode_item: btrfs_inode_item_to_disk_v,	\
+		struct btrfs_root_backup: btrfs_root_backup_to_disk_v,	\
+		struct btrfs_dev_item: btrfs_dev_item_to_disk_v		\
+		)((d->x));
+
+# define DEFINE_CONV_LE_TO_CPU(x)					\
+	(d->x) = _Generic((d->x),					\
+		__u16: le16_to_cpu,					\
+		__u32: le32_to_cpu,					\
+		__u64: le64_to_cpu,					\
+		struct btrfs_key: btrfs_key_to_cpu_v,			\
+		struct btrfs_stripe: btrfs_stripe_to_cpu_v,		\
+		struct btrfs_timespec: btrfs_timespec_to_cpu_v,		\
+		struct btrfs_inode_item: btrfs_inode_item_to_cpu_v,	\
+		struct btrfs_root_backup: btrfs_root_backup_to_cpu_v,	\
+		struct btrfs_dev_item: btrfs_dev_item_to_cpu_v		\
+		)((d->x));
+
+# define DEFINE_CONV_ONE(t,n,m,...)			\
+	static inline struct t * n(struct t * d) {	\
+		CALL_MACRO_FOR_EACH(m, ##__VA_ARGS__)	\
+		return d;				\
+	}
+
+/* Finally define the DEFINE_CONV macro */
+# define DEFINE_CONV(n,...) \
+	DEFINE_CONV_ONE(n,n##_to_disk,DEFINE_CONV_CPU_TO_LE,##__VA_ARGS__) \
+	DEFINE_CONV_ONE(n,n##_to_cpu,DEFINE_CONV_LE_TO_CPU,##__VA_ARGS__)
+
+# define DEFINE_CONV_ALT(n,a,...) \
+	DEFINE_CONV_ONE(n,n##_to_disk_##a,DEFINE_CONV_CPU_TO_LE, \
+		##__VA_ARGS__) \
+	DEFINE_CONV_ONE(n,n##_to_cpu_##a,DEFINE_CONV_LE_TO_CPU,##__VA_ARGS__)
+
+#endif /* !defined(__LITTLE_ENDIAN) */
+
+DEFINE_CONV(btrfs_key, objectid, offset)
+DEFINE_CONV(btrfs_dev_item, devid, total_bytes, bytes_used, io_align, io_width,
+	    sector_size, type, generation, start_offset, dev_group)
+DEFINE_CONV(btrfs_stripe, devid, offset)
+DEFINE_CONV(btrfs_chunk, length, owner, stripe_len, type, io_align, io_width,
+	    sector_size, num_stripes, sub_stripes)
+DEFINE_CONV(btrfs_free_space_entry, offset, bytes)
+DEFINE_CONV(btrfs_free_space_header, location, generation, num_entries,
+	    num_bitmaps)
+DEFINE_CONV(btrfs_extent_item, refs, generation, flags)
+DEFINE_CONV(btrfs_tree_block_info, key)
+DEFINE_CONV(btrfs_extent_data_ref, root, objectid, offset, count)
+DEFINE_CONV(btrfs_shared_data_ref, count)
+DEFINE_CONV(btrfs_extent_inline_ref, offset)
+DEFINE_CONV(btrfs_dev_extent, chunk_tree, chunk_objectid, chunk_offset, length)
+DEFINE_CONV(btrfs_inode_ref, index, name_len)
+DEFINE_CONV(btrfs_inode_extref, parent_objectid, index, name_len)
+DEFINE_CONV(btrfs_timespec, sec, nsec)
+DEFINE_CONV(btrfs_inode_item, generation, transid, size, nbytes, block_group,
+	    nlink, uid, gid, mode, rdev, flags, sequence, atime, ctime, mtime,
+	    otime)
+DEFINE_CONV(btrfs_dir_log_item, end)
+DEFINE_CONV(btrfs_dir_item, location, transid, data_len, name_len)
+DEFINE_CONV(btrfs_root_item, inode, generation, root_dirid, bytenr, byte_limit,
+	    bytes_used, last_snapshot, flags, refs, drop_progress,
+	    generation_v2, ctransid, otransid, stransid, rtransid, ctime,
+	    otime, stime, rtime)
+DEFINE_CONV(btrfs_root_ref, dirid, sequence, name_len)
+DEFINE_CONV(btrfs_file_extent_item, generation, ram_bytes, other_encoding,
+	    disk_bytenr, disk_num_bytes, offset, num_bytes)
+DEFINE_CONV_ALT(btrfs_file_extent_item, inl, generation, ram_bytes,
+		other_encoding)
+DEFINE_CONV(btrfs_dev_replace_item, src_devid, cursor_left, cursor_right,
+	    cont_reading_from_srcdev_mode, replace_state, time_started,
+	    time_stopped, num_write_errors, num_uncorrectable_read_errors)
+DEFINE_CONV(btrfs_block_group_item, used, chunk_objectid, flags)
+DEFINE_CONV(btrfs_free_space_info, extent_count, flags)
+
+DEFINE_CONV(btrfs_header, bytenr, flags, generation, owner, nritems)
+DEFINE_CONV(btrfs_root_backup, tree_root, tree_root_gen, chunk_root,
+	    chunk_root_gen, extent_root, extent_root_gen, fs_root, fs_root_gen,
+	    dev_root, dev_root_gen, csum_root, csum_root_gen, total_bytes,
+	    bytes_used, num_devices)
+DEFINE_CONV(btrfs_super_block, bytenr, flags, magic, generation, root,
+	    chunk_root, log_root, log_root_transid, total_bytes, bytes_used,
+	    root_dir_objectid, num_devices, sectorsize, nodesize,
+	    __unused_leafsize, stripesize, sys_chunk_array_size,
+	    chunk_root_generation, compat_flags, compat_ro_flags,
+	    incompat_flags, csum_type, dev_item, cache_generation,
+	    uuid_tree_generation, super_roots[0], super_roots[1], 
+	    super_roots[2], super_roots[3])
+DEFINE_CONV(btrfs_item, key, offset, size)
+DEFINE_CONV(btrfs_key_ptr, key, blockptr, generation)
+
+#endif /* __BTRFS_CONV_FUNCS_H__ */