Add basic RAID[56] support

David Woodhouse originally contributed this code, and Chris Mason
changed it around to reflect the current design goals for raid56.

The original code expected all metadata and data writes to be full
stripes.  This meant metadata block size == stripe size, and had a few
other restrictions.

This version allows metadata blocks smaller than the stripe size.  It
implements both raid5 and raid6, although it does not have code to
rebuild from parity if one of the drives is missing or incorrect.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/disk-io.h b/disk-io.h
index 53e9b17a..53ef0238 100644
--- a/disk-io.h
+++ b/disk-io.h
@@ -82,3 +82,6 @@ int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf,
 		    int verify);
 int btrfs_read_buffer(struct extent_buffer *buf, u64 parent_transid);
 #endif
+
+/* raid6.c */
+void raid6_gen_syndrome(int disks, size_t bytes, void **ptrs);