xfs: use XFS_BMAP_BMDR_SPACE vs. XFS_BROOT_SIZE_ADJ

XFS_BROOT_SIZE_ADJ is an undocumented macro which accounts for
the difference in size between the on-disk and in-core btree
root.  It's much clearer to just use the newly-added
XFS_BMAP_BMDR_SPACE macro which gives us the on-disk size
directly.

In one case, we must test that the if_broot exists before
applying the macro, however.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

fs/xfs/xfs_dinode.h

@@ -132,9 +132,6 @@ typedef enum xfs_dinode_fmt {
 #define XFS_LITINO(mp, version) \
 	((int)(((mp)->m_sb.sb_inodesize) - xfs_dinode_size(version)))
 
-#define XFS_BROOT_SIZE_ADJ(ip) \
-	(XFS_BMBT_BLOCK_LEN((ip)->i_mount) - sizeof(xfs_bmdr_block_t))
-
 /*
  * Inode data & attribute fork sizes, per inode.
  */

fs/xfs/xfs_inode.c

@@ -2156,8 +2156,8 @@ xfs_iroot_realloc(
 		np = (char *)XFS_BMAP_BROOT_PTR_ADDR(mp, ifp->if_broot, 1,
 						     (int)new_size);
 		ifp->if_broot_bytes = (int)new_size;
-		ASSERT(ifp->if_broot_bytes <=
-			XFS_IFORK_SIZE(ip, whichfork) + XFS_BROOT_SIZE_ADJ(ip));
+		ASSERT(XFS_BMAP_BMDR_SPACE(ifp->if_broot) <=
+			XFS_IFORK_SIZE(ip, whichfork));
 		memmove(np, op, cur_max * (uint)sizeof(xfs_dfsbno_t));
 		return;
 	}
@@ -2210,8 +2210,9 @@ xfs_iroot_realloc(
 	kmem_free(ifp->if_broot);
 	ifp->if_broot = new_broot;
 	ifp->if_broot_bytes = (int)new_size;
-	ASSERT(ifp->if_broot_bytes <=
-		XFS_IFORK_SIZE(ip, whichfork) + XFS_BROOT_SIZE_ADJ(ip));
+	if (ifp->if_broot)
+		ASSERT(XFS_BMAP_BMDR_SPACE(ifp->if_broot) <=
+			XFS_IFORK_SIZE(ip, whichfork));
 	return;
 }
 
@@ -2522,9 +2523,8 @@ xfs_iflush_fork(
 		if ((iip->ili_fields & brootflag[whichfork]) &&
 		    (ifp->if_broot_bytes > 0)) {
 			ASSERT(ifp->if_broot != NULL);
-			ASSERT(ifp->if_broot_bytes <=
-			       (XFS_IFORK_SIZE(ip, whichfork) +
-				XFS_BROOT_SIZE_ADJ(ip)));
+			ASSERT(XFS_BMAP_BMDR_SPACE(ifp->if_broot) <=
+			        XFS_IFORK_SIZE(ip, whichfork));
 			xfs_bmbt_to_bmdr(mp, ifp->if_broot, ifp->if_broot_bytes,
 				(xfs_bmdr_block_t *)cp,
 				XFS_DFORK_SIZE(dip, mp, whichfork));