[PATCH RFC v2 1/8] btrfs: add raid stripe tree definitions

[Johannes Thumshirn <johannes.thumshirn@wdc.com>]

Add definitions for the raid-stripe-tree. This tree will hold informatioin
about the on-disk layout of the stripes in a RAID set.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 fs/btrfs/ctree.h                | 29 +++++++++++++++++++++++++++++
 include/uapi/linux/btrfs_tree.h | 17 +++++++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 4e2569f84aab..18e2f186cb5e 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1906,6 +1906,35 @@ BTRFS_SETGET_FUNCS(timespec_nsec, struct btrfs_timespec, nsec, 32);
 BTRFS_SETGET_STACK_FUNCS(stack_timespec_sec, struct btrfs_timespec, sec, 64);
 BTRFS_SETGET_STACK_FUNCS(stack_timespec_nsec, struct btrfs_timespec, nsec, 32);
 
+BTRFS_SETGET_FUNCS(stripe_extent_devid, struct btrfs_stripe_extent, devid, 64);
+BTRFS_SETGET_FUNCS(stripe_extent_physical, struct btrfs_stripe_extent, physical, 64);
+BTRFS_SETGET_STACK_FUNCS(stack_stripe_extent_devid, struct btrfs_stripe_extent, devid, 64);
+BTRFS_SETGET_STACK_FUNCS(stack_stripe_extent_physical, struct btrfs_stripe_extent, physical, 64);
+
+static inline struct btrfs_stripe_extent *btrfs_stripe_extent_nr(
+					 struct btrfs_dp_stripe *dps, int nr)
+{
+	unsigned long offset = (unsigned long)dps;
+
+	offset += offsetof(struct btrfs_dp_stripe, extents);
+	offset += nr * sizeof(struct btrfs_stripe_extent);
+	return (struct btrfs_stripe_extent *)offset;
+}
+
+static inline u64 btrfs_stripe_extent_devid_nr(const struct extent_buffer *eb,
+					       struct btrfs_dp_stripe *dps,
+					       int nr)
+{
+	return btrfs_stripe_extent_devid(eb, btrfs_stripe_extent_nr(dps, nr));
+}
+
+static inline u64 btrfs_stripe_extent_physical_nr(const struct extent_buffer *eb,
+						  struct btrfs_dp_stripe *dps,
+						  int nr)
+{
+	return btrfs_stripe_extent_physical(eb, btrfs_stripe_extent_nr(dps, nr));
+}
+
 /* struct btrfs_dev_extent */
 BTRFS_SETGET_FUNCS(dev_extent_chunk_tree, struct btrfs_dev_extent,
 		   chunk_tree, 64);
diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
index d4117152d907..070fc9266821 100644
--- a/include/uapi/linux/btrfs_tree.h
+++ b/include/uapi/linux/btrfs_tree.h
@@ -56,6 +56,9 @@
 /* Holds the block group items for extent tree v2. */
 #define BTRFS_BLOCK_GROUP_TREE_OBJECTID 11ULL
 
+/* tracks RAID stripes in block groups. */
+#define BTRFS_RAID_STRIPE_TREE_OBJECTID 12ULL
+
 /* device stats in the device tree */
 #define BTRFS_DEV_STATS_OBJECTID 0ULL
 
@@ -264,6 +267,8 @@
  */
 #define BTRFS_QGROUP_RELATION_KEY       246
 
+#define BTRFS_RAID_STRIPE_KEY		247
+
 /*
  * Obsolete name, see BTRFS_TEMPORARY_ITEM_KEY.
  */
@@ -488,6 +493,18 @@ struct btrfs_free_space_header {
 	__le64 num_bitmaps;
 } __attribute__ ((__packed__));
 
+struct btrfs_stripe_extent {
+	/* btrfs device-id this raid extent lives on */
+	__le64 devid;
+	/* physical location on disk */
+	__le64 physical;
+} __attribute__ ((__packed__));
+
+struct btrfs_dp_stripe {
+	/* array of stripe extents this stripe is composed of */
+	DECLARE_FLEX_ARRAY(struct btrfs_stripe_extent, extents);
+} __attribute__ ((__packed__));
+
 #define BTRFS_HEADER_FLAG_WRITTEN	(1ULL << 0)
 #define BTRFS_HEADER_FLAG_RELOC		(1ULL << 1)
 
-- 
2.35.3