xfs: remove struct xfs_dabuf and infrastructure

The struct xfs_dabuf now only tracks a single xfs_buf and all the
information it holds can be gained directly from the xfs_buf. Hence
we can remove the struct dabuf and pass the xfs_buf around
everywhere.

Kill the struct dabuf and the associated infrastructure.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ben Myers <bpm@sgi.com>

diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 425f6e9..07f70e1 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1491,13 +1491,9 @@
 	if (!xfs_da_state_zone)
 		goto out_destroy_btree_cur_zone;
 
-	xfs_dabuf_zone = kmem_zone_init(sizeof(xfs_dabuf_t), "xfs_dabuf");
-	if (!xfs_dabuf_zone)
-		goto out_destroy_da_state_zone;
-
 	xfs_ifork_zone = kmem_zone_init(sizeof(xfs_ifork_t), "xfs_ifork");
 	if (!xfs_ifork_zone)
-		goto out_destroy_dabuf_zone;
+		goto out_destroy_da_state_zone;
 
 	xfs_trans_zone = kmem_zone_init(sizeof(xfs_trans_t), "xfs_trans");
 	if (!xfs_trans_zone)
@@ -1560,8 +1556,6 @@
 	kmem_zone_destroy(xfs_trans_zone);
  out_destroy_ifork_zone:
 	kmem_zone_destroy(xfs_ifork_zone);
- out_destroy_dabuf_zone:
-	kmem_zone_destroy(xfs_dabuf_zone);
  out_destroy_da_state_zone:
 	kmem_zone_destroy(xfs_da_state_zone);
  out_destroy_btree_cur_zone:
@@ -1589,7 +1583,6 @@
 	kmem_zone_destroy(xfs_log_item_desc_zone);
 	kmem_zone_destroy(xfs_trans_zone);
 	kmem_zone_destroy(xfs_ifork_zone);
-	kmem_zone_destroy(xfs_dabuf_zone);
 	kmem_zone_destroy(xfs_da_state_zone);
 	kmem_zone_destroy(xfs_btree_cur_zone);
 	kmem_zone_destroy(xfs_bmap_free_item_zone);