+#define BTRFS_SUPER_MIRROR_MAX 3
+#define BTRFS_SUPER_MIRROR_SHIFT 12
+
+enum btrfs_open_ctree_flags {
+ /* Open filesystem for writes */
+ OPEN_CTREE_WRITES = (1U << 0),
+ /* Allow to open filesystem with some broken tree roots (eg log root) */
+ OPEN_CTREE_PARTIAL = (1U << 1),
+ /* If primary root pinters are invalid, try backup copies */
+ OPEN_CTREE_BACKUP_ROOT = (1U << 2),
+ /* Allow reading all superblock sopies if the primary is damaged */
+ OPEN_CTREE_RECOVER_SUPER = (1U << 3),
+ /* Restoring filesystem image */
+ OPEN_CTREE_RESTORE = (1U << 4),
+ /* Do not read block groups (extent tree) */
+ OPEN_CTREE_NO_BLOCK_GROUPS = (1U << 5),
+ /* Open all devices in O_EXCL mode */
+ OPEN_CTREE_EXCLUSIVE = (1U << 6),
+ /* Do not scan devices */
+ OPEN_CTREE_NO_DEVICES = (1U << 7),
+ /*
+ * Don't print error messages if bytenr or checksums do not match in
+ * tree block headers. Turn on by OPEN_CTREE_SUPPRESS_ERROR
+ */
+ OPEN_CTREE_SUPPRESS_CHECK_BLOCK_ERRORS = (1U << 8),
+ /* Return the chunk root */
+ __OPEN_CTREE_RETURN_CHUNK_ROOT = (1U << 9),
+ OPEN_CTREE_CHUNK_ROOT_ONLY = OPEN_CTREE_PARTIAL +
+ OPEN_CTREE_SUPPRESS_CHECK_BLOCK_ERRORS +
+ __OPEN_CTREE_RETURN_CHUNK_ROOT,
+ /*
+ * TODO: cleanup: Split the open_ctree_flags into more independent
+ * Tree bits.
+ * Like split PARTIAL into SKIP_CSUM/SKIP_EXTENT
+ */
+
+ /* Ignore UUID mismatches */
+ OPEN_CTREE_IGNORE_FSID_MISMATCH = (1U << 10),
+
+ /*
+ * Allow open_ctree_fs_info() to return an incomplete fs_info with
+ * system chunks from super block only.
+ * It's useful when chunks are corrupted.
+ * Makes no sense for open_ctree variants returning btrfs_root.
+ */
+ OPEN_CTREE_IGNORE_CHUNK_TREE_ERROR = (1U << 11),
+
+ /* Allow to open a partially created filesystem */
+ OPEN_CTREE_FS_PARTIAL = (1U << 12),
+
+ /*
+ * Invalidate the free space tree (i.e., clear the FREE_SPACE_TREE_VALID
+ * compat_ro bit).
+ */
+ OPEN_CTREE_INVALIDATE_FST = (1U << 13),
+};
+
+/*
+ * Modes of superblock access
+ */
+enum btrfs_read_sb_flags {
+ SBREAD_DEFAULT = 0,
+ /* Reading superblock during recovery */
+ SBREAD_RECOVER = (1 << 0),
+
+ /*
+ * Read superblock with the fake signature, cannot be used with
+ * SBREAD_RECOVER
+ */
+ SBREAD_PARTIAL = (1 << 1),
+};
+
+/*
+ * Use macro to define mirror super block position,
+ * so we can use it in static array initialization
+ */
+#define BTRFS_SB_MIRROR_OFFSET(mirror) ((u64)(SZ_16K) << \
+ (BTRFS_SUPER_MIRROR_SHIFT * (mirror)))
+
+static inline u64 btrfs_sb_offset(int mirror)
+{
+ if (mirror)
+ return BTRFS_SB_MIRROR_OFFSET(mirror);
+ return BTRFS_SUPER_INFO_OFFSET;
+}
+