[XFS] add generic btree types

Add generic union types for btree pointers, keys and records. The generic
btree pointer contains either a 32 and 64bit big endian scalar for short
and long form btrees, and the key and record contain the relevant type for
each possible btree.

Split out from a bigger patch from Dave Chinner and simplified a little
further.

SGI-PV: 985583

SGI-Modid: xfs-linux-melb:xfs-kern:32178a

Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Bill O'Donnell <billodo@sgi.com>
Signed-off-by: David Chinner <david@fromorbit.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/fs/xfs/xfs_btree.h b/fs/xfs/xfs_btree.h
index d30ee7498606..428e81f0e27e 100644
--- a/fs/xfs/xfs_btree.h
+++ b/fs/xfs/xfs_btree.h
@@ -80,6 +80,31 @@ typedef struct xfs_btree_block {
 } xfs_btree_block_t;
 
 /*
+ * Generic key, ptr and record wrapper structures.
+ *
+ * These are disk format structures, and are converted where necessary
+ * by the btree specific code that needs to interpret them.
+ */
+union xfs_btree_ptr {
+        __be32                  s;      /* short form ptr */
+        __be64                  l;      /* long form ptr */
+};
+
+union xfs_btree_key {
+        xfs_bmbt_key_t          bmbt;
+        xfs_bmdr_key_t          bmbr;   /* bmbt root block */
+        xfs_alloc_key_t         alloc;
+        xfs_inobt_key_t         inobt;
+};
+
+union xfs_btree_rec {
+        xfs_bmbt_rec_t          bmbt;
+        xfs_bmdr_rec_t          bmbr;   /* bmbt root block */
+        xfs_alloc_rec_t         alloc;
+        xfs_inobt_rec_t         inobt;
+};
+
+/*
  * For logging record fields.
  */
 #define XFS_BB_MAGIC            0x01