xfs: get rid of the log item descriptor

It's just a connector between a transaction and a log item. There's
a 1:1 relationship between a log item descriptor and a log item,
and a 1:1 relationship between a log item descriptor and a
transaction. Both relationships are created and terminated at the
same time, so why do we even have the descriptor?

Replace it with a specific list_head in the log item and a new
log item dirtied flag to replace the XFS_LID_DIRTY flag.

Signed-Off-By: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
[darrick: fix up deferred agfl intent finish_item use of LID_DIRTY]
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
diff --git a/fs/xfs/xfs_trans_refcount.c b/fs/xfs/xfs_trans_refcount.c
index 94c1877..c7f8e82 100644
--- a/fs/xfs/xfs_trans_refcount.c
+++ b/fs/xfs/xfs_trans_refcount.c
@@ -77,7 +77,7 @@ xfs_trans_log_finish_refcount_update(
 	 * 2.) shuts down the filesystem
 	 */
 	tp->t_flags |= XFS_TRANS_DIRTY;
-	cudp->cud_item.li_desc->lid_flags |= XFS_LID_DIRTY;
+	set_bit(XFS_LI_DIRTY, &cudp->cud_item.li_flags);
 
 	return error;
 }
@@ -154,7 +154,7 @@ xfs_refcount_update_log_item(
 	refc = container_of(item, struct xfs_refcount_intent, ri_list);
 
 	tp->t_flags |= XFS_TRANS_DIRTY;
-	cuip->cui_item.li_desc->lid_flags |= XFS_LID_DIRTY;
+	set_bit(XFS_LI_DIRTY, &cuip->cui_item.li_flags);
 
 	/*
 	 * atomic_inc_return gives us the value after the increment;