[PATCH 03/26] add generic btree types

[Christoph Hellwig <hch@lst.de>]

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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@lst.de>

Index: linux-2.6-xfs/fs/xfs/xfs_btree.h
===================================================================
--- linux-2.6-xfs.orig/fs/xfs/xfs_btree.h	2008-08-02 04:01:46.000000000 +0200
+++ linux-2.6-xfs/fs/xfs/xfs_btree.h	2008-08-02 04:04:16.000000000 +0200
@@ -79,6 +79,31 @@ typedef struct xfs_btree_block {
 	} bb_u;				/* rest */
 } 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.
  */

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