tree 1b2cfcf4152e09f32a6cb0bcbd798d5dab2f5490
parent d20f7043fa65659136c1a7c3c456eeeb5c6f431f
author Yan Zheng <zheng.yan@oracle.com> 1228772786 -0500
committer Chris Mason <chris.mason@oracle.com> 1228772786 -0500

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>