xfs: during btree split, save new block key & ptr for future insertion

When a btree block has to be split, we pass the new block's ptr from
xfs_btree_split() back to xfs_btree_insert() via a pointer parameter;
however, we pass the block's key through the cursor's record.  It is a
little weird to "initialize" a record from a key since the non-key
attributes will have garbage values.

When we go to add support for interval queries, we have to be able to
pass the lowest and highest keys accessible via a pointer.  There's no
clean way to pass this back through the cursor's record field.
Therefore, pass the key directly back to xfs_btree_insert() the same
way that we pass the btree_ptr.

As a bonus, we no longer need init_rec_from_key and can drop it from the
codebase.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/xfs/libxfs/xfs_bmap_btree.c

@@ -599,17 +599,6 @@ xfs_bmbt_init_key_from_rec(
 		cpu_to_be64(xfs_bmbt_disk_get_startoff(&rec->bmbt));
 }
 
-STATIC void
-xfs_bmbt_init_rec_from_key(
-	union xfs_btree_key	*key,
-	union xfs_btree_rec	*rec)
-{
-	ASSERT(key->bmbt.br_startoff != 0);
-
-	xfs_bmbt_disk_set_allf(&rec->bmbt, be64_to_cpu(key->bmbt.br_startoff),
-			       0, 0, XFS_EXT_NORM);
-}
-
 STATIC void
 xfs_bmbt_init_rec_from_cur(
 	struct xfs_btree_cur	*cur,
@@ -760,7 +749,6 @@ static const struct xfs_btree_ops xfs_bmbt_ops = {
 	.get_minrecs		= xfs_bmbt_get_minrecs,
 	.get_dmaxrecs		= xfs_bmbt_get_dmaxrecs,
 	.init_key_from_rec	= xfs_bmbt_init_key_from_rec,
-	.init_rec_from_key	= xfs_bmbt_init_rec_from_key,
 	.init_rec_from_cur	= xfs_bmbt_init_rec_from_cur,
 	.init_ptr_from_cur	= xfs_bmbt_init_ptr_from_cur,
 	.key_diff		= xfs_bmbt_key_diff,