[PATCH v4 1/2] btrfs: Move on-disk structure definition to btrfs_tree.h

[Qu Wenruo <wqu@suse.com>]

These structures all are on-disk format. Move them to btrfs_tree.h

This allows us to sync the header to different projects, who need to
read btrfs filesystem, like U-boot, grub.

With this modification, all on-disk format is definite in btrfs_tree.h,
and can be easily synced to other projects.

This move includes:
- btrfs magic
  It's a surprise that it's not even definied in btrfs_tree.h

- tree block max level
  Move it before btrfs_header definition.

- tree block backref revision
- btrfs_header structure
- btrfs_root_backup structure
- btrfs_super_block structure
- BTRFS_FEATURE_* flags
- BTRFS_(FSID|UUID|LABEL)_SIZE macros
- BTRFS_MAX_METADATA_BLOCKSIZE macro
- BTRFS_NAME_LEN macro

- btrfs_item structure
- btrfs_leaf structure
- btrfs_key_ptr structure
- btrfs_node structure

- btrfs_dev_stat_values
  Since on-disk format btrfs_dev_stats_item needs it.

- BTRFS_INODE_* flags
- BTRFS_QGROUP_LIMIT_* flags

- enum btrfs_compression_type
  With this movement, btrfs_tree is completely self-contained.
  It only needs <linux/types.h> header.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 fs/btrfs/compression.h          |   9 +-
 fs/btrfs/ctree.h                | 246 -----------------------
 include/uapi/linux/btrfs.h      |  74 +------
 include/uapi/linux/btrfs_tree.h | 338 +++++++++++++++++++++++++++++++-
 4 files changed, 336 insertions(+), 331 deletions(-)

diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
index d253f7aa8ed5..65f6f31a7ec4 100644
--- a/fs/btrfs/compression.h
+++ b/fs/btrfs/compression.h
@@ -7,6 +7,7 @@
 #define BTRFS_COMPRESSION_H
 
 #include <linux/sizes.h>
+#include <linux/btrfs_tree.h>
 
 /*
  * We want to make sure that amount of RAM required to uncompress an extent is
@@ -100,14 +101,6 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 
 unsigned int btrfs_compress_str2level(unsigned int type, const char *str);
 
-enum btrfs_compression_type {
-	BTRFS_COMPRESS_NONE  = 0,
-	BTRFS_COMPRESS_ZLIB  = 1,
-	BTRFS_COMPRESS_LZO   = 2,
-	BTRFS_COMPRESS_ZSTD  = 3,
-	BTRFS_NR_COMPRESS_TYPES = 4,
-};
-
 struct workspace_manager {
 	struct list_head idle_ws;
 	spinlock_t ws_lock;
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 8aa7b9dac405..4d787d749315 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -49,8 +49,6 @@ extern struct kmem_cache *btrfs_free_space_bitmap_cachep;
 struct btrfs_ordered_sum;
 struct btrfs_ref;
 
-#define BTRFS_MAGIC 0x4D5F53665248425FULL /* ascii _BHRfS_M, no null */
-
 /*
  * Maximum number of mirrors that can be available for all profiles counting
  * the target device of dev-replace as one. During an active device replace
@@ -62,22 +60,8 @@ struct btrfs_ref;
  */
 #define BTRFS_MAX_MIRRORS (4 + 1)
 
-#define BTRFS_MAX_LEVEL 8
-
 #define BTRFS_OLDEST_GENERATION	0ULL
 
-/*
- * the max metadata block size.  This limit is somewhat artificial,
- * but the memmove costs go through the roof for larger blocks.
- */
-#define BTRFS_MAX_METADATA_BLOCKSIZE 65536
-
-/*
- * we can actually store much bigger names, but lets not confuse the rest
- * of linux
- */
-#define BTRFS_NAME_LEN 255
-
 /*
  * Theoretical limit is larger, but we keep this down to a sane
  * value. That should limit greatly the possibility of collisions on
@@ -148,203 +132,6 @@ enum {
 	BTRFS_FS_STATE_DUMMY_FS_INFO,
 };
 
-#define BTRFS_BACKREF_REV_MAX		256
-#define BTRFS_BACKREF_REV_SHIFT		56
-#define BTRFS_BACKREF_REV_MASK		(((u64)BTRFS_BACKREF_REV_MAX - 1) << \
-					 BTRFS_BACKREF_REV_SHIFT)
-
-#define BTRFS_OLD_BACKREF_REV		0
-#define BTRFS_MIXED_BACKREF_REV		1
-
-/*
- * every tree block (leaf or node) starts with this header.
- */
-struct btrfs_header {
-	/* these first four must match the super block */
-	u8 csum[BTRFS_CSUM_SIZE];
-	u8 fsid[BTRFS_FSID_SIZE]; /* FS specific uuid */
-	__le64 bytenr; /* which block this node is supposed to live in */
-	__le64 flags;
-
-	/* allowed to be different from the super from here on down */
-	u8 chunk_tree_uuid[BTRFS_UUID_SIZE];
-	__le64 generation;
-	__le64 owner;
-	__le32 nritems;
-	u8 level;
-} __attribute__ ((__packed__));
-
-/*
- * this is a very generous portion of the super block, giving us
- * room to translate 14 chunks with 3 stripes each.
- */
-#define BTRFS_SYSTEM_CHUNK_ARRAY_SIZE 2048
-
-/*
- * just in case we somehow lose the roots and are not able to mount,
- * we store an array of the roots from previous transactions
- * in the super.
- */
-#define BTRFS_NUM_BACKUP_ROOTS 4
-struct btrfs_root_backup {
-	__le64 tree_root;
-	__le64 tree_root_gen;
-
-	__le64 chunk_root;
-	__le64 chunk_root_gen;
-
-	__le64 extent_root;
-	__le64 extent_root_gen;
-
-	__le64 fs_root;
-	__le64 fs_root_gen;
-
-	__le64 dev_root;
-	__le64 dev_root_gen;
-
-	__le64 csum_root;
-	__le64 csum_root_gen;
-
-	__le64 total_bytes;
-	__le64 bytes_used;
-	__le64 num_devices;
-	/* future */
-	__le64 unused_64[4];
-
-	u8 tree_root_level;
-	u8 chunk_root_level;
-	u8 extent_root_level;
-	u8 fs_root_level;
-	u8 dev_root_level;
-	u8 csum_root_level;
-	/* future and to align */
-	u8 unused_8[10];
-} __attribute__ ((__packed__));
-
-/*
- * the super block basically lists the main trees of the FS
- * it currently lacks any block count etc etc
- */
-struct btrfs_super_block {
-	/* the first 4 fields must match struct btrfs_header */
-	u8 csum[BTRFS_CSUM_SIZE];
-	/* FS specific UUID, visible to user */
-	u8 fsid[BTRFS_FSID_SIZE];
-	__le64 bytenr; /* this block number */
-	__le64 flags;
-
-	/* allowed to be different from the btrfs_header from here own down */
-	__le64 magic;
-	__le64 generation;
-	__le64 root;
-	__le64 chunk_root;
-	__le64 log_root;
-
-	/* this will help find the new super based on the log root */
-	__le64 log_root_transid;
-	__le64 total_bytes;
-	__le64 bytes_used;
-	__le64 root_dir_objectid;
-	__le64 num_devices;
-	__le32 sectorsize;
-	__le32 nodesize;
-	__le32 __unused_leafsize;
-	__le32 stripesize;
-	__le32 sys_chunk_array_size;
-	__le64 chunk_root_generation;
-	__le64 compat_flags;
-	__le64 compat_ro_flags;
-	__le64 incompat_flags;
-	__le16 csum_type;
-	u8 root_level;
-	u8 chunk_root_level;
-	u8 log_root_level;
-	struct btrfs_dev_item dev_item;
-
-	char label[BTRFS_LABEL_SIZE];
-
-	__le64 cache_generation;
-	__le64 uuid_tree_generation;
-
-	/* the UUID written into btree blocks */
-	u8 metadata_uuid[BTRFS_FSID_SIZE];
-
-	/* future expansion */
-	__le64 reserved[28];
-	u8 sys_chunk_array[BTRFS_SYSTEM_CHUNK_ARRAY_SIZE];
-	struct btrfs_root_backup super_roots[BTRFS_NUM_BACKUP_ROOTS];
-} __attribute__ ((__packed__));
-
-/*
- * Compat flags that we support.  If any incompat flags are set other than the
- * ones specified below then we will fail to mount
- */
-#define BTRFS_FEATURE_COMPAT_SUPP		0ULL
-#define BTRFS_FEATURE_COMPAT_SAFE_SET		0ULL
-#define BTRFS_FEATURE_COMPAT_SAFE_CLEAR		0ULL
-
-#define BTRFS_FEATURE_COMPAT_RO_SUPP			\
-	(BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE |	\
-	 BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE_VALID)
-
-#define BTRFS_FEATURE_COMPAT_RO_SAFE_SET	0ULL
-#define BTRFS_FEATURE_COMPAT_RO_SAFE_CLEAR	0ULL
-
-#define BTRFS_FEATURE_INCOMPAT_SUPP			\
-	(BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF |		\
-	 BTRFS_FEATURE_INCOMPAT_DEFAULT_SUBVOL |	\
-	 BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS |		\
-	 BTRFS_FEATURE_INCOMPAT_BIG_METADATA |		\
-	 BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO |		\
-	 BTRFS_FEATURE_INCOMPAT_COMPRESS_ZSTD |		\
-	 BTRFS_FEATURE_INCOMPAT_RAID56 |		\
-	 BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF |		\
-	 BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA |	\
-	 BTRFS_FEATURE_INCOMPAT_NO_HOLES	|	\
-	 BTRFS_FEATURE_INCOMPAT_METADATA_UUID	|	\
-	 BTRFS_FEATURE_INCOMPAT_RAID1C34)
-
-#define BTRFS_FEATURE_INCOMPAT_SAFE_SET			\
-	(BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF)
-#define BTRFS_FEATURE_INCOMPAT_SAFE_CLEAR		0ULL
-
-/*
- * A leaf is full of items. offset and size tell us where to find
- * the item in the leaf (relative to the start of the data area)
- */
-struct btrfs_item {
-	struct btrfs_disk_key key;
-	__le32 offset;
-	__le32 size;
-} __attribute__ ((__packed__));
-
-/*
- * leaves have an item area and a data area:
- * [item0, item1....itemN] [free space] [dataN...data1, data0]
- *
- * The data is separate from the items to get the keys closer together
- * during searches.
- */
-struct btrfs_leaf {
-	struct btrfs_header header;
-	struct btrfs_item items[];
-} __attribute__ ((__packed__));
-
-/*
- * all non-leaf blocks are nodes, they hold only keys and pointers to
- * other blocks
- */
-struct btrfs_key_ptr {
-	struct btrfs_disk_key key;
-	__le64 blockptr;
-	__le64 generation;
-} __attribute__ ((__packed__));
-
-struct btrfs_node {
-	struct btrfs_header header;
-	struct btrfs_key_ptr ptrs[];
-} __attribute__ ((__packed__));
-
 /*
  * btrfs_paths remember the path taken from the root down to the leaf.
  * level 0 is always the leaf, and nodes[1...BTRFS_MAX_LEVEL] will point
@@ -1307,39 +1094,6 @@ do {                                                                   \
        }                                                               \
 } while(0)
 
-/*
- * Inode flags
- */
-#define BTRFS_INODE_NODATASUM		(1 << 0)
-#define BTRFS_INODE_NODATACOW		(1 << 1)
-#define BTRFS_INODE_READONLY		(1 << 2)
-#define BTRFS_INODE_NOCOMPRESS		(1 << 3)
-#define BTRFS_INODE_PREALLOC		(1 << 4)
-#define BTRFS_INODE_SYNC		(1 << 5)
-#define BTRFS_INODE_IMMUTABLE		(1 << 6)
-#define BTRFS_INODE_APPEND		(1 << 7)
-#define BTRFS_INODE_NODUMP		(1 << 8)
-#define BTRFS_INODE_NOATIME		(1 << 9)
-#define BTRFS_INODE_DIRSYNC		(1 << 10)
-#define BTRFS_INODE_COMPRESS		(1 << 11)
-
-#define BTRFS_INODE_ROOT_ITEM_INIT	(1 << 31)
-
-#define BTRFS_INODE_FLAG_MASK						\
-	(BTRFS_INODE_NODATASUM |					\
-	 BTRFS_INODE_NODATACOW |					\
-	 BTRFS_INODE_READONLY |						\
-	 BTRFS_INODE_NOCOMPRESS |					\
-	 BTRFS_INODE_PREALLOC |						\
-	 BTRFS_INODE_SYNC |						\
-	 BTRFS_INODE_IMMUTABLE |					\
-	 BTRFS_INODE_APPEND |						\
-	 BTRFS_INODE_NODUMP |						\
-	 BTRFS_INODE_NOATIME |						\
-	 BTRFS_INODE_DIRSYNC |						\
-	 BTRFS_INODE_COMPRESS |						\
-	 BTRFS_INODE_ROOT_ITEM_INIT)
-
 struct btrfs_map_token {
 	const struct extent_buffer *eb;
 	char *kaddr;
diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index 8134924cfc17..69c2c21e7f7b 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -21,10 +21,10 @@
 #define _UAPI_LINUX_BTRFS_H
 #include <linux/types.h>
 #include <linux/ioctl.h>
+#include <linux/btrfs_tree.h>
 
 #define BTRFS_IOCTL_MAGIC 0x94
 #define BTRFS_VOL_NAME_MAX 255
-#define BTRFS_LABEL_SIZE 256
 
 /* this should be 4k */
 #define BTRFS_PATH_NAME_MAX 4087
@@ -55,24 +55,8 @@ struct btrfs_ioctl_vol_args {
 			BTRFS_DEVICE_SPEC_BY_ID |	\
 			BTRFS_SUBVOL_SPEC_BY_ID)
 
-#define BTRFS_FSID_SIZE 16
-#define BTRFS_UUID_SIZE 16
 #define BTRFS_UUID_UNPARSED_SIZE	37
 
-/*
- * flags definition for qgroup limits
- *
- * Used by:
- * struct btrfs_qgroup_limit.flags
- * struct btrfs_qgroup_limit_item.flags
- */
-#define BTRFS_QGROUP_LIMIT_MAX_RFER	(1ULL << 0)
-#define BTRFS_QGROUP_LIMIT_MAX_EXCL	(1ULL << 1)
-#define BTRFS_QGROUP_LIMIT_RSV_RFER	(1ULL << 2)
-#define BTRFS_QGROUP_LIMIT_RSV_EXCL	(1ULL << 3)
-#define BTRFS_QGROUP_LIMIT_RFER_CMPR	(1ULL << 4)
-#define BTRFS_QGROUP_LIMIT_EXCL_CMPR	(1ULL << 5)
-
 struct btrfs_qgroup_limit {
 	__u64	flags;
 	__u64	max_rfer;
@@ -256,43 +240,6 @@ struct btrfs_ioctl_fs_info_args {
 	__u64 reserved[122];			/* pad to 1k */
 };
 
-/*
- * feature flags
- *
- * Used by:
- * struct btrfs_ioctl_feature_flags
- */
-#define BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE		(1ULL << 0)
-/*
- * Older kernels (< 4.9) on big-endian systems produced broken free space tree
- * bitmaps, and btrfs-progs also used to corrupt the free space tree (versions
- * < 4.7.3).  If this bit is clear, then the free space tree cannot be trusted.
- * btrfs-progs can also intentionally clear this bit to ask the kernel to
- * rebuild the free space tree, however this might not work on older kernels
- * that do not know about this bit. If not sure, clear the cache manually on
- * first mount when booting older kernel versions.
- */
-#define BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE_VALID	(1ULL << 1)
-
-#define BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF	(1ULL << 0)
-#define BTRFS_FEATURE_INCOMPAT_DEFAULT_SUBVOL	(1ULL << 1)
-#define BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS	(1ULL << 2)
-#define BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO	(1ULL << 3)
-#define BTRFS_FEATURE_INCOMPAT_COMPRESS_ZSTD	(1ULL << 4)
-
-/*
- * older kernels tried to do bigger metadata blocks, but the
- * code was pretty buggy.  Lets not let them try anymore.
- */
-#define BTRFS_FEATURE_INCOMPAT_BIG_METADATA	(1ULL << 5)
-
-#define BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF	(1ULL << 6)
-#define BTRFS_FEATURE_INCOMPAT_RAID56		(1ULL << 7)
-#define BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA	(1ULL << 8)
-#define BTRFS_FEATURE_INCOMPAT_NO_HOLES		(1ULL << 9)
-#define BTRFS_FEATURE_INCOMPAT_METADATA_UUID	(1ULL << 10)
-#define BTRFS_FEATURE_INCOMPAT_RAID1C34		(1ULL << 11)
-
 struct btrfs_ioctl_feature_flags {
 	__u64 compat_flags;
 	__u64 compat_ro_flags;
@@ -657,25 +604,6 @@ struct btrfs_ioctl_logical_ino_args {
  * Requires logical == extent bytenr. */
 #define BTRFS_LOGICAL_INO_ARGS_IGNORE_OFFSET	(1ULL << 0)
 
-enum btrfs_dev_stat_values {
-	/* disk I/O failure stats */
-	BTRFS_DEV_STAT_WRITE_ERRS, /* EIO or EREMOTEIO from lower layers */
-	BTRFS_DEV_STAT_READ_ERRS, /* EIO or EREMOTEIO from lower layers */
-	BTRFS_DEV_STAT_FLUSH_ERRS, /* EIO or EREMOTEIO from lower layers */
-
-	/* stats for indirect indications for I/O failures */
-	BTRFS_DEV_STAT_CORRUPTION_ERRS, /* checksum error, bytenr error or
-					 * contents is illegal: this is an
-					 * indication that the block was damaged
-					 * during read or write, or written to
-					 * wrong location or read from wrong
-					 * location */
-	BTRFS_DEV_STAT_GENERATION_ERRS, /* an indication that blocks have not
-					 * been written */
-
-	BTRFS_DEV_STAT_VALUES_MAX
-};
-
 /* Reset statistics after reading; needs SYS_ADMIN capability */
 #define	BTRFS_DEV_STATS_RESET		(1ULL << 0)
 
diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
index 8e322e2c7e78..1170be498c43 100644
--- a/include/uapi/linux/btrfs_tree.h
+++ b/include/uapi/linux/btrfs_tree.h
@@ -2,9 +2,26 @@
 #ifndef _BTRFS_CTREE_H_
 #define _BTRFS_CTREE_H_
 
-#include <linux/btrfs.h>
 #include <linux/types.h>
 
+#define BTRFS_MAGIC 0x4D5F53665248425FULL /* ascii _BHRfS_M, no null */
+
+/*
+ * The max metadata block size (node size).
+ *
+ * This limit is somewhat artificial. The memmove and tree block locking cost
+ * go up with larger node size.
+ */
+#define BTRFS_MAX_METADATA_BLOCKSIZE 65536
+
+/*
+ * We can actually store much bigger names, but lets not confuse the rest
+ * of linux.
+ *
+ * btrfs_dir_item::name_len follows this limitation.
+ */
+#define BTRFS_NAME_LEN 255
+
 /*
  * This header contains the structure definitions and constants used
  * by file system objects that can be retrieved using
@@ -281,9 +298,6 @@
  * The key is built like this:
  * (UUID_upper_64_bits, BTRFS_UUID_KEY*, UUID_lower_64_bits).
  */
-#if BTRFS_UUID_SIZE != 16
-#error "UUID items require BTRFS_UUID_SIZE == 16!"
-#endif
 #define BTRFS_UUID_KEY_SUBVOL	251	/* for UUIDs assigned to subvols */
 #define BTRFS_UUID_KEY_RECEIVED_SUBVOL	252	/* for UUIDs assigned to
 						 * received subvols */
@@ -326,6 +340,9 @@ enum btrfs_csum_type {
 #define BTRFS_FT_XATTR		8
 #define BTRFS_FT_MAX		9
 
+#define BTRFS_FSID_SIZE 16
+#define BTRFS_UUID_SIZE 16
+
 /*
  * The key defines the order in the tree, and so it also defines (optimal)
  * block layout.
@@ -559,6 +576,39 @@ struct btrfs_timespec {
 	__le32 nsec;
 } __attribute__ ((__packed__));
 
+/*
+ * Inode flags
+ */
+#define BTRFS_INODE_NODATASUM		(1 << 0)
+#define BTRFS_INODE_NODATACOW		(1 << 1)
+#define BTRFS_INODE_READONLY		(1 << 2)
+#define BTRFS_INODE_NOCOMPRESS		(1 << 3)
+#define BTRFS_INODE_PREALLOC		(1 << 4)
+#define BTRFS_INODE_SYNC		(1 << 5)
+#define BTRFS_INODE_IMMUTABLE		(1 << 6)
+#define BTRFS_INODE_APPEND		(1 << 7)
+#define BTRFS_INODE_NODUMP		(1 << 8)
+#define BTRFS_INODE_NOATIME		(1 << 9)
+#define BTRFS_INODE_DIRSYNC		(1 << 10)
+#define BTRFS_INODE_COMPRESS		(1 << 11)
+
+#define BTRFS_INODE_ROOT_ITEM_INIT	(1 << 31)
+
+#define BTRFS_INODE_FLAG_MASK						\
+	(BTRFS_INODE_NODATASUM |					\
+	 BTRFS_INODE_NODATACOW |					\
+	 BTRFS_INODE_READONLY |						\
+	 BTRFS_INODE_NOCOMPRESS |					\
+	 BTRFS_INODE_PREALLOC |						\
+	 BTRFS_INODE_SYNC |						\
+	 BTRFS_INODE_IMMUTABLE |					\
+	 BTRFS_INODE_APPEND |						\
+	 BTRFS_INODE_NODUMP |						\
+	 BTRFS_INODE_NOATIME |						\
+	 BTRFS_INODE_DIRSYNC |						\
+	 BTRFS_INODE_COMPRESS |						\
+	 BTRFS_INODE_ROOT_ITEM_INIT)
+
 struct btrfs_inode_item {
 	/* nfs style generation number */
 	__le64 generation;
@@ -747,6 +797,14 @@ enum {
 	BTRFS_NR_FILE_EXTENT_TYPES = 3,
 };
 
+enum btrfs_compression_type {
+	BTRFS_COMPRESS_NONE  = 0,
+	BTRFS_COMPRESS_ZLIB  = 1,
+	BTRFS_COMPRESS_LZO   = 2,
+	BTRFS_COMPRESS_ZSTD  = 3,
+	BTRFS_NR_COMPRESS_TYPES = 4,
+};
+
 struct btrfs_file_extent_item {
 	/*
 	 * transaction id that created this extent
@@ -803,6 +861,25 @@ struct btrfs_csum_item {
 	__u8 csum;
 } __attribute__ ((__packed__));
 
+enum btrfs_dev_stat_values {
+	/* disk I/O failure stats */
+	BTRFS_DEV_STAT_WRITE_ERRS, /* EIO or EREMOTEIO from lower layers */
+	BTRFS_DEV_STAT_READ_ERRS, /* EIO or EREMOTEIO from lower layers */
+	BTRFS_DEV_STAT_FLUSH_ERRS, /* EIO or EREMOTEIO from lower layers */
+
+	/* stats for indirect indications for I/O failures */
+	BTRFS_DEV_STAT_CORRUPTION_ERRS, /* checksum error, bytenr error or
+					 * contents is illegal: this is an
+					 * indication that the block was damaged
+					 * during read or write, or written to
+					 * wrong location or read from wrong
+					 * location */
+	BTRFS_DEV_STAT_GENERATION_ERRS, /* an indication that blocks have not
+					 * been written */
+
+	BTRFS_DEV_STAT_VALUES_MAX
+};
+
 struct btrfs_dev_stats_item {
 	/*
 	 * grow this item struct at the end for future enhancements and keep
@@ -974,6 +1051,20 @@ struct btrfs_qgroup_info_item {
 	__le64 excl_cmpr;
 } __attribute__ ((__packed__));
 
+/*
+ * flags definition for qgroup limits
+ *
+ * Used by:
+ * struct btrfs_qgroup_limit.flags
+ * struct btrfs_qgroup_limit_item.flags
+ */
+#define BTRFS_QGROUP_LIMIT_MAX_RFER	(1ULL << 0)
+#define BTRFS_QGROUP_LIMIT_MAX_EXCL	(1ULL << 1)
+#define BTRFS_QGROUP_LIMIT_RSV_RFER	(1ULL << 2)
+#define BTRFS_QGROUP_LIMIT_RSV_EXCL	(1ULL << 3)
+#define BTRFS_QGROUP_LIMIT_RFER_CMPR	(1ULL << 4)
+#define BTRFS_QGROUP_LIMIT_EXCL_CMPR	(1ULL << 5)
+
 struct btrfs_qgroup_limit_item {
 	/*
 	 * only updated when any of the other values change
@@ -985,4 +1076,243 @@ struct btrfs_qgroup_limit_item {
 	__le64 rsv_excl;
 } __attribute__ ((__packed__));
 
+/*
+ * just in case we somehow lose the roots and are not able to mount,
+ * we store an array of the roots from previous transactions
+ * in the super.
+ */
+#define BTRFS_NUM_BACKUP_ROOTS 4
+struct btrfs_root_backup {
+	__le64 tree_root;
+	__le64 tree_root_gen;
+
+	__le64 chunk_root;
+	__le64 chunk_root_gen;
+
+	__le64 extent_root;
+	__le64 extent_root_gen;
+
+	__le64 fs_root;
+	__le64 fs_root_gen;
+
+	__le64 dev_root;
+	__le64 dev_root_gen;
+
+	__le64 csum_root;
+	__le64 csum_root_gen;
+
+	__le64 total_bytes;
+	__le64 bytes_used;
+	__le64 num_devices;
+	/* future */
+	__le64 unused_64[4];
+
+	u8 tree_root_level;
+	u8 chunk_root_level;
+	u8 extent_root_level;
+	u8 fs_root_level;
+	u8 dev_root_level;
+	u8 csum_root_level;
+	/* future and to align */
+	u8 unused_8[10];
+} __attribute__ ((__packed__));
+
+/*
+ * this is a very generous portion of the super block, giving us
+ * room to translate 14 chunks with 3 stripes each.
+ */
+#define BTRFS_SYSTEM_CHUNK_ARRAY_SIZE 2048
+
+#define BTRFS_LABEL_SIZE 256
+/*
+ * the super block basically lists the main trees of the FS
+ * it currently lacks any block count etc etc
+ */
+struct btrfs_super_block {
+	/* the first 4 fields must match struct btrfs_header */
+	u8 csum[BTRFS_CSUM_SIZE];
+	/* FS specific UUID, visible to user */
+	u8 fsid[BTRFS_FSID_SIZE];
+	__le64 bytenr; /* this block number */
+	__le64 flags;
+
+	/* allowed to be different from the btrfs_header from here own down */
+	__le64 magic;
+	__le64 generation;
+	__le64 root;
+	__le64 chunk_root;
+	__le64 log_root;
+
+	/* this will help find the new super based on the log root */
+	__le64 log_root_transid;
+	__le64 total_bytes;
+	__le64 bytes_used;
+	__le64 root_dir_objectid;
+	__le64 num_devices;
+	__le32 sectorsize;
+	__le32 nodesize;
+	__le32 __unused_leafsize;
+	__le32 stripesize;
+	__le32 sys_chunk_array_size;
+	__le64 chunk_root_generation;
+	__le64 compat_flags;
+	__le64 compat_ro_flags;
+	__le64 incompat_flags;
+	__le16 csum_type;
+	u8 root_level;
+	u8 chunk_root_level;
+	u8 log_root_level;
+	struct btrfs_dev_item dev_item;
+
+	char label[BTRFS_LABEL_SIZE];
+
+	__le64 cache_generation;
+	__le64 uuid_tree_generation;
+
+	/* the UUID written into btree blocks */
+	u8 metadata_uuid[BTRFS_FSID_SIZE];
+
+	/* future expansion */
+	__le64 reserved[28];
+	u8 sys_chunk_array[BTRFS_SYSTEM_CHUNK_ARRAY_SIZE];
+	struct btrfs_root_backup super_roots[BTRFS_NUM_BACKUP_ROOTS];
+} __attribute__ ((__packed__));
+
+/*
+ * feature flags
+ *
+ * Used by:
+ * struct btrfs_super_block::(compat|compat_ro|incompat)_flags
+ * struct btrfs_ioctl_feature_flags
+ */
+#define BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE		(1ULL << 0)
+
+/*
+ * Older kernels (< 4.9) on big-endian systems produced broken free space tree
+ * bitmaps, and btrfs-progs also used to corrupt the free space tree (versions
+ * < 4.7.3).  If this bit is clear, then the free space tree cannot be trusted.
+ * btrfs-progs can also intentionally clear this bit to ask the kernel to
+ * rebuild the free space tree, however this might not work on older kernels
+ * that do not know about this bit. If not sure, clear the cache manually on
+ * first mount when booting older kernel versions.
+ */
+#define BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE_VALID	(1ULL << 1)
+
+#define BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF	(1ULL << 0)
+#define BTRFS_FEATURE_INCOMPAT_DEFAULT_SUBVOL	(1ULL << 1)
+#define BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS	(1ULL << 2)
+#define BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO	(1ULL << 3)
+#define BTRFS_FEATURE_INCOMPAT_COMPRESS_ZSTD	(1ULL << 4)
+
+/*
+ * older kernels tried to do bigger metadata blocks, but the
+ * code was pretty buggy.  Lets not let them try anymore.
+ */
+#define BTRFS_FEATURE_INCOMPAT_BIG_METADATA	(1ULL << 5)
+
+#define BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF	(1ULL << 6)
+#define BTRFS_FEATURE_INCOMPAT_RAID56		(1ULL << 7)
+#define BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA	(1ULL << 8)
+#define BTRFS_FEATURE_INCOMPAT_NO_HOLES		(1ULL << 9)
+#define BTRFS_FEATURE_INCOMPAT_METADATA_UUID	(1ULL << 10)
+#define BTRFS_FEATURE_INCOMPAT_RAID1C34		(1ULL << 11)
+
+/*
+ * Compat flags that we support.  If any incompat flags are set other than the
+ * ones specified below then we will fail to mount
+ */
+#define BTRFS_FEATURE_COMPAT_SUPP		0ULL
+#define BTRFS_FEATURE_COMPAT_SAFE_SET		0ULL
+#define BTRFS_FEATURE_COMPAT_SAFE_CLEAR		0ULL
+
+#define BTRFS_FEATURE_COMPAT_RO_SUPP			\
+	(BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE |	\
+	 BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE_VALID)
+
+#define BTRFS_FEATURE_COMPAT_RO_SAFE_SET	0ULL
+#define BTRFS_FEATURE_COMPAT_RO_SAFE_CLEAR	0ULL
+
+#define BTRFS_FEATURE_INCOMPAT_SUPP			\
+	(BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF |		\
+	 BTRFS_FEATURE_INCOMPAT_DEFAULT_SUBVOL |	\
+	 BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS |		\
+	 BTRFS_FEATURE_INCOMPAT_BIG_METADATA |		\
+	 BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO |		\
+	 BTRFS_FEATURE_INCOMPAT_COMPRESS_ZSTD |		\
+	 BTRFS_FEATURE_INCOMPAT_RAID56 |		\
+	 BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF |		\
+	 BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA |	\
+	 BTRFS_FEATURE_INCOMPAT_NO_HOLES	|	\
+	 BTRFS_FEATURE_INCOMPAT_METADATA_UUID	|	\
+	 BTRFS_FEATURE_INCOMPAT_RAID1C34)
+
+#define BTRFS_FEATURE_INCOMPAT_SAFE_SET			\
+	(BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF)
+#define BTRFS_FEATURE_INCOMPAT_SAFE_CLEAR		0ULL
+
+#define BTRFS_BACKREF_REV_MAX		256
+#define BTRFS_BACKREF_REV_SHIFT		56
+#define BTRFS_BACKREF_REV_MASK		(((u64)BTRFS_BACKREF_REV_MAX - 1) << \
+					 BTRFS_BACKREF_REV_SHIFT)
+
+#define BTRFS_OLD_BACKREF_REV		0
+#define BTRFS_MIXED_BACKREF_REV		1
+
+#define BTRFS_MAX_LEVEL 8
+
+/*
+ * every tree block (leaf or node) starts with this header.
+ */
+struct btrfs_header {
+	/* these first four must match the super block */
+	u8 csum[BTRFS_CSUM_SIZE];
+	u8 fsid[BTRFS_FSID_SIZE]; /* FS specific uuid */
+	__le64 bytenr; /* which block this node is supposed to live in */
+	__le64 flags;
+
+	/* allowed to be different from the super from here on down */
+	u8 chunk_tree_uuid[BTRFS_UUID_SIZE];
+	__le64 generation;
+	__le64 owner;
+	__le32 nritems;
+	u8 level;
+} __attribute__ ((__packed__));
+
+/*
+ * A leaf is full of items. offset and size tell us where to find
+ * the item in the leaf (relative to the start of the data area)
+ */
+struct btrfs_item {
+	struct btrfs_disk_key key;
+	__le32 offset;
+	__le32 size;
+} __attribute__ ((__packed__));
+
+/*
+ * leaves have an item area and a data area:
+ * [item0, item1....itemN] [free space] [dataN...data1, data0]
+ *
+ * The data is separate from the items to get the keys closer together
+ * during searches.
+ */
+struct btrfs_leaf {
+	struct btrfs_header header;
+	struct btrfs_item items[];
+} __attribute__ ((__packed__));
+
+/*
+ * all non-leaf blocks are nodes, they hold only keys and pointers to
+ * other blocks
+ */
+struct btrfs_key_ptr {
+	struct btrfs_disk_key key;
+	__le64 blockptr;
+	__le64 generation;
+} __attribute__ ((__packed__));
+
+struct btrfs_node {
+	struct btrfs_header header;
+	struct btrfs_key_ptr ptrs[];
+} __attribute__ ((__packed__));
+
 #endif /* _BTRFS_CTREE_H_ */
-- 
2.26.0