xfs: turn dfp_done into a xfs_log_item

All defer op instance place their own extension of the log item into
the dfp_done field.  Replace that with a xfs_log_item to improve type
safety and make the code easier to follow.

Also use the opportunity to improve the ->finish_item calling conventions
to place the done log item as the higher level structure before the
list_entry used for the individual items.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/libxfs/xfs_defer.c

@@ -371,7 +371,7 @@ xfs_defer_finish_one(
 	list_for_each_safe(li, n, &dfp->dfp_work) {
 		list_del(li);
 		dfp->dfp_count--;
-		error = ops->finish_item(tp, li, dfp->dfp_done, &state);
+		error = ops->finish_item(tp, dfp->dfp_done, li, &state);
 		if (error == -EAGAIN) {
 			/*
 			 * Caller wants a fresh transaction; put the work item

fs/xfs/libxfs/xfs_defer.h

@@ -29,7 +29,7 @@ struct xfs_defer_pending {
 	struct list_head		dfp_list;	/* pending items */
 	struct list_head		dfp_work;	/* work items */
 	struct xfs_log_item		*dfp_intent;	/* log intent item */
-	void				*dfp_done;	/* log done item */
+	struct xfs_log_item		*dfp_done;	/* log done item */
 	unsigned int			dfp_count;	/* # extent items */
 	enum xfs_defer_ops_type		dfp_type;
 };
@@ -46,10 +46,10 @@ struct xfs_defer_op_type {
 	struct xfs_log_item *(*create_intent)(struct xfs_trans *tp,
 			struct list_head *items, unsigned int count, bool sort);
 	void (*abort_intent)(struct xfs_log_item *intent);
-	void *(*create_done)(struct xfs_trans *tp, struct xfs_log_item *intent,
-			unsigned int count);
-	int (*finish_item)(struct xfs_trans *, struct list_head *, void *,
-			void **);
+	struct xfs_log_item *(*create_done)(struct xfs_trans *tp,
+			struct xfs_log_item *intent, unsigned int count);
+	int (*finish_item)(struct xfs_trans *tp, struct xfs_log_item *done,
+			struct list_head *item, void **state);
 	void (*finish_cleanup)(struct xfs_trans *, void *, int);
 	void (*cancel_item)(struct list_head *);
 	unsigned int		max_items;

fs/xfs/xfs_bmap_item.c

@@ -352,21 +352,21 @@ xfs_bmap_update_create_intent(
 }
 
 /* Get an BUD so we can process all the deferred rmap updates. */
-STATIC void *
+static struct xfs_log_item *
 xfs_bmap_update_create_done(
 	struct xfs_trans		*tp,
 	struct xfs_log_item		*intent,
 	unsigned int			count)
 {
-	return xfs_trans_get_bud(tp, BUI_ITEM(intent));
+	return &xfs_trans_get_bud(tp, BUI_ITEM(intent))->bud_item;
 }
 
 /* Process a deferred rmap update. */
 STATIC int
 xfs_bmap_update_finish_item(
 	struct xfs_trans		*tp,
+	struct xfs_log_item		*done,
 	struct list_head		*item,
-	void				*done_item,
 	void				**state)
 {
 	struct xfs_bmap_intent		*bmap;
@@ -375,7 +375,7 @@ xfs_bmap_update_finish_item(
 
 	bmap = container_of(item, struct xfs_bmap_intent, bi_list);
 	count = bmap->bi_bmap.br_blockcount;
-	error = xfs_trans_log_finish_bmap_update(tp, done_item,
+	error = xfs_trans_log_finish_bmap_update(tp, BUD_ITEM(done),
 			bmap->bi_type,
 			bmap->bi_owner, bmap->bi_whichfork,
 			bmap->bi_bmap.br_startoff,

fs/xfs/xfs_extfree_item.c

@@ -459,28 +459,28 @@ xfs_extent_free_create_intent(
 }
 
 /* Get an EFD so we can process all the free extents. */
-STATIC void *
+static struct xfs_log_item *
 xfs_extent_free_create_done(
 	struct xfs_trans		*tp,
 	struct xfs_log_item		*intent,
 	unsigned int			count)
 {
-	return xfs_trans_get_efd(tp, EFI_ITEM(intent), count);
+	return &xfs_trans_get_efd(tp, EFI_ITEM(intent), count)->efd_item;
 }
 
 /* Process a free extent. */
 STATIC int
 xfs_extent_free_finish_item(
 	struct xfs_trans		*tp,
+	struct xfs_log_item		*done,
 	struct list_head		*item,
-	void				*done_item,
 	void				**state)
 {
 	struct xfs_extent_free_item	*free;
 	int				error;
 
 	free = container_of(item, struct xfs_extent_free_item, xefi_list);
-	error = xfs_trans_free_extent(tp, done_item,
+	error = xfs_trans_free_extent(tp, EFD_ITEM(done),
 			free->xefi_startblock,
 			free->xefi_blockcount,
 			&free->xefi_oinfo, free->xefi_skip_discard);
@@ -523,12 +523,12 @@ const struct xfs_defer_op_type xfs_extent_free_defer_type = {
 STATIC int
 xfs_agfl_free_finish_item(
 	struct xfs_trans		*tp,
+	struct xfs_log_item		*done,
 	struct list_head		*item,
-	void				*done_item,
 	void				**state)
 {
 	struct xfs_mount		*mp = tp->t_mountp;
-	struct xfs_efd_log_item		*efdp = done_item;
+	struct xfs_efd_log_item		*efdp = EFD_ITEM(done);
 	struct xfs_extent_free_item	*free;
 	struct xfs_extent		*extp;
 	struct xfs_buf			*agbp;

fs/xfs/xfs_refcount_item.c

@@ -351,21 +351,21 @@ xfs_refcount_update_create_intent(
 }
 
 /* Get an CUD so we can process all the deferred refcount updates. */
-STATIC void *
+static struct xfs_log_item *
 xfs_refcount_update_create_done(
 	struct xfs_trans		*tp,
 	struct xfs_log_item		*intent,
 	unsigned int			count)
 {
-	return xfs_trans_get_cud(tp, CUI_ITEM(intent));
+	return &xfs_trans_get_cud(tp, CUI_ITEM(intent))->cud_item;
 }
 
 /* Process a deferred refcount update. */
 STATIC int
 xfs_refcount_update_finish_item(
 	struct xfs_trans		*tp,
+	struct xfs_log_item		*done,
 	struct list_head		*item,
-	void				*done_item,
 	void				**state)
 {
 	struct xfs_refcount_intent	*refc;
@@ -374,7 +374,7 @@ xfs_refcount_update_finish_item(
 	int				error;
 
 	refc = container_of(item, struct xfs_refcount_intent, ri_list);
-	error = xfs_trans_log_finish_refcount_update(tp, done_item,
+	error = xfs_trans_log_finish_refcount_update(tp, CUD_ITEM(done),
 			refc->ri_type,
 			refc->ri_startblock,
 			refc->ri_blockcount,

fs/xfs/xfs_rmap_item.c

@@ -403,28 +403,28 @@ xfs_rmap_update_create_intent(
 }
 
 /* Get an RUD so we can process all the deferred rmap updates. */
-STATIC void *
+static struct xfs_log_item *
 xfs_rmap_update_create_done(
 	struct xfs_trans		*tp,
 	struct xfs_log_item		*intent,
 	unsigned int			count)
 {
-	return xfs_trans_get_rud(tp, RUI_ITEM(intent));
+	return &xfs_trans_get_rud(tp, RUI_ITEM(intent))->rud_item;
 }
 
 /* Process a deferred rmap update. */
 STATIC int
 xfs_rmap_update_finish_item(
 	struct xfs_trans		*tp,
+	struct xfs_log_item		*done,
 	struct list_head		*item,
-	void				*done_item,
 	void				**state)
 {
 	struct xfs_rmap_intent		*rmap;
 	int				error;
 
 	rmap = container_of(item, struct xfs_rmap_intent, ri_list);
-	error = xfs_trans_log_finish_rmap_update(tp, done_item,
+	error = xfs_trans_log_finish_rmap_update(tp, RUD_ITEM(done),
 			rmap->ri_type,
 			rmap->ri_owner, rmap->ri_whichfork,
 			rmap->ri_bmap.br_startoff,