[PATCH 02/21] add generic btree types

[Christoph Hellwig <hch@xxxxxx>]

Add generic union types for btree pointers, keys and records.  The generic
btree pointer contains a 32 and 64bit big endian type 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.


Signed-off-by: Christoph Hellwig <hch@xxxxxx>

Index: linux-2.6-xfs/fs/xfs/xfs_btree.h
===================================================================
--- linux-2.6-xfs.orig/fs/xfs/xfs_btree.h       2008-07-14 17:26:11.000000000 
+0200
+++ linux-2.6-xfs/fs/xfs/xfs_btree.h    2008-07-14 17:27:59.000000000 +0200
@@ -70,6 +70,12 @@ typedef struct xfs_btree_hdr
        __be16          bb_numrecs;     /* current # of data records */
 } xfs_btree_hdr_t;
 
+/*
+ * Generic block, key, ptr and record wrapper structures
+ * These are disk format structures, and are converted where
+ * necessary be the btree specific code that needs to interpret
+ * them.
+ */
 typedef struct xfs_btree_block {
        xfs_btree_hdr_t bb_h;           /* header */
        union {
@@ -84,6 +90,25 @@ typedef struct xfs_btree_block {
        } bb_u;                         /* rest */
 } xfs_btree_block_t;
 
+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.
  */

--