Btrfs: superblock duplication

This patch implements superblock duplication. Superblocks
are stored at offset 16K, 64M and 256G on every devices.
Spaces used by superblocks are preserved by the allocator,
which uses a reverse mapping function to find the logical
addresses that correspond to superblocks. Thank you,

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
This commit is contained in:
Yan Zheng
2008-12-08 16:46:26 -05:00
committed by Chris Mason
parent d20f7043fa
commit a512bbf855
8 changed files with 279 additions and 119 deletions

View File

@@ -19,8 +19,20 @@
#ifndef __DISKIO__
#define __DISKIO__
#define BTRFS_SUPER_INFO_OFFSET (16 * 1024)
#define BTRFS_SUPER_INFO_OFFSET (64 * 1024)
#define BTRFS_SUPER_INFO_SIZE 4096
#define BTRFS_SUPER_MIRROR_MAX 3
#define BTRFS_SUPER_MIRROR_SHIFT 12
static inline u64 btrfs_sb_offset(int mirror)
{
u64 start = 16 * 1024;
if (mirror)
return start << (BTRFS_SUPER_MIRROR_SHIFT * mirror);
return BTRFS_SUPER_INFO_OFFSET;
}
struct btrfs_device;
struct btrfs_fs_devices;
@@ -37,7 +49,8 @@ struct btrfs_root *open_ctree(struct super_block *sb,
char *options);
int close_ctree(struct btrfs_root *root);
int write_ctree_super(struct btrfs_trans_handle *trans,
struct btrfs_root *root);
struct btrfs_root *root, int max_mirrors);
struct buffer_head *btrfs_read_dev_super(struct block_device *bdev);
int btrfs_commit_super(struct btrfs_root *root);
struct extent_buffer *btrfs_find_tree_block(struct btrfs_root *root,
u64 bytenr, u32 blocksize);