bcachefs: Move deletion of refcount=0 indirect extents to their triggers

For backpointers, we need to switch the order triggers are run in: we
need to run triggers for deletions/overwrites before triggers for
inserts.

To avoid breaking the reflink triggers, this patch moves deleting of
indirect extents with refcount=0 to their triggers, instead of doing it
when we update those keys.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

fs/bcachefs/buckets.c

@@ -1798,11 +1798,6 @@ static int __bch2_trans_mark_reflink_p(struct btree_trans *trans,
 
 	le64_add_cpu(refcount, add);
 
-	if (!*refcount) {
-		n->k.type = KEY_TYPE_deleted;
-		set_bkey_val_u64s(&n->k, 0);
-	}
-
 	bch2_btree_iter_set_pos_to_extent_start(&iter);
 	ret = bch2_trans_update(trans, &iter, n, 0);
 	if (ret)

fs/bcachefs/reflink.c

@@ -98,6 +98,24 @@ bool bch2_reflink_v_merge(struct bch_fs *c, struct bkey_s _l, struct bkey_s_c _r
 	return l.v->refcount == r.v->refcount && bch2_extent_merge(c, _l, _r);
 }
 
+int bch2_trans_mark_reflink_v(struct btree_trans *trans,
+			      struct bkey_s_c old, struct bkey_i *new,
+			      unsigned flags)
+{
+	if (!(flags & BTREE_TRIGGER_OVERWRITE)) {
+		struct bkey_i_reflink_v *r = bkey_i_to_reflink_v(new);
+
+		if (!r->v.refcount) {
+			r->k.type = KEY_TYPE_deleted;
+			r->k.size = 0;
+			set_bkey_val_u64s(&r->k, 0);
+			return 0;
+		}
+	}
+
+	return bch2_trans_mark_extent(trans, old, new, flags);
+}
+
 /* indirect inline data */
 
 const char *bch2_indirect_inline_data_invalid(const struct bch_fs *c,
@@ -119,6 +137,24 @@ void bch2_indirect_inline_data_to_text(struct printbuf *out,
 	       min(datalen, 32U), d.v->data);
 }
 
+int bch2_trans_mark_indirect_inline_data(struct btree_trans *trans,
+			      struct bkey_s_c old, struct bkey_i *new,
+			      unsigned flags)
+{
+	if (!(flags & BTREE_TRIGGER_OVERWRITE)) {
+		struct bkey_i_indirect_inline_data *r =
+			bkey_i_to_indirect_inline_data(new);
+
+		if (!r->v.refcount) {
+			r->k.type = KEY_TYPE_deleted;
+			r->k.size = 0;
+			set_bkey_val_u64s(&r->k, 0);
+		}
+	}
+
+	return 0;
+}
+
 static int bch2_make_extent_indirect(struct btree_trans *trans,
 				     struct btree_iter *extent_iter,
 				     struct bkey_i *orig)

fs/bcachefs/reflink.h

@@ -18,12 +18,14 @@ bool bch2_reflink_p_merge(struct bch_fs *, struct bkey_s, struct bkey_s_c);
 const char *bch2_reflink_v_invalid(const struct bch_fs *, struct bkey_s_c);
 void bch2_reflink_v_to_text(struct printbuf *, struct bch_fs *,
 			    struct bkey_s_c);
+int bch2_trans_mark_reflink_v(struct btree_trans *, struct bkey_s_c,
+			      struct bkey_i *, unsigned);
 
 #define bch2_bkey_ops_reflink_v (struct bkey_ops) {		\
 	.key_invalid	= bch2_reflink_v_invalid,		\
 	.val_to_text	= bch2_reflink_v_to_text,		\
 	.swab		= bch2_ptr_swab,			\
-	.trans_trigger	= bch2_trans_mark_extent,		\
+	.trans_trigger	= bch2_trans_mark_reflink_v,		\
 	.atomic_trigger	= bch2_mark_extent,			\
 }
 
@@ -31,10 +33,14 @@ const char *bch2_indirect_inline_data_invalid(const struct bch_fs *,
 					      struct bkey_s_c);
 void bch2_indirect_inline_data_to_text(struct printbuf *,
 				struct bch_fs *, struct bkey_s_c);
+int bch2_trans_mark_indirect_inline_data(struct btree_trans *,
+			      struct bkey_s_c, struct bkey_i *,
+			      unsigned);
 
 #define bch2_bkey_ops_indirect_inline_data (struct bkey_ops) {	\
 	.key_invalid	= bch2_indirect_inline_data_invalid,	\
 	.val_to_text	= bch2_indirect_inline_data_to_text,	\
+	.trans_trigger	= bch2_trans_mark_indirect_inline_data,	\
 }
 
 static inline const __le64 *bkey_refcount_c(struct bkey_s_c k)