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authorYan Zheng <zheng.yan@oracle.com>2008-12-09 00:46:26 +0300
committerChris Mason <chris.mason@oracle.com>2008-12-09 00:46:26 +0300
commita512bbf855ff0af474257475f2e6da7acd854f52 (patch)
tree1b2cfcf4152e09f32a6cb0bcbd798d5dab2f5490 /fs/btrfs/disk-io.h
parentd20f7043fa65659136c1a7c3c456eeeb5c6f431f (diff)
downloadlinux-a512bbf855ff0af474257475f2e6da7acd854f52.tar.xz
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>
Diffstat (limited to 'fs/btrfs/disk-io.h')
-rw-r--r--fs/btrfs/disk-io.h17
1 files changed, 15 insertions, 2 deletions
diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
index 717e94811e4e..c0ff404c31b7 100644
--- a/fs/btrfs/disk-io.h
+++ b/fs/btrfs/disk-io.h
@@ -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);