bcachefs: Don't get journal reservation until after we know insert will succeed

Checking if we can do the insert after getting the journal reservation
means potentially wasting space in the journal, which will break the new
pre reservation mechanism
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_update_leaf.c

@@ -416,6 +416,25 @@ static inline int btree_trans_cmp(struct btree_insert_entry l,
 		btree_iter_cmp(l.iter, r.iter);
 }
 
+static bool btree_trans_relock(struct btree_insert *trans)
+{
+	struct btree_insert_entry *i;
+
+	trans_for_each_iter(trans, i)
+		return bch2_btree_iter_relock(i->iter);
+	return true;
+}
+
+static void btree_trans_unlock(struct btree_insert *trans)
+{
+	struct btree_insert_entry *i;
+
+	trans_for_each_iter(trans, i) {
+		bch2_btree_iter_unlock(i->iter);
+		break;
+	}
+}
+
 /* Normal update interface: */
 
 static enum btree_insert_ret
@@ -467,49 +486,12 @@ static inline int do_btree_insert_at(struct btree_insert *trans,
 	struct btree_iter *linked;
 	unsigned u64s;
 	int ret;
-
+retry:
 	trans_for_each_iter(trans, i)
 		BUG_ON(i->iter->uptodate >= BTREE_ITER_NEED_RELOCK);
 
-	/* reserve space for deferred updates */
-	__trans_for_each_entry(trans, i, i->deferred) {
-
-	}
-
 	memset(&trans->journal_res, 0, sizeof(trans->journal_res));
 
-	if (likely(!(trans->flags & BTREE_INSERT_JOURNAL_REPLAY))) {
-		u64s = 0;
-		trans_for_each_entry(trans, i)
-			u64s += jset_u64s(i->k->k.u64s);
-
-		while ((ret = bch2_journal_res_get(&c->journal,
-					&trans->journal_res, u64s,
-					JOURNAL_RES_GET_NONBLOCK)) == -EAGAIN) {
-			struct btree_iter *iter = NULL;
-
-			trans_for_each_iter(trans, i)
-				iter = i->iter;
-
-			if (iter)
-				bch2_btree_iter_unlock(iter);
-
-			ret = bch2_journal_res_get(&c->journal,
-					&trans->journal_res, u64s,
-					JOURNAL_RES_GET_CHECK);
-			if (ret)
-				return ret;
-
-			if (iter && !bch2_btree_iter_relock(iter)) {
-				trans_restart(" (iter relock after journal res get blocked)");
-				return -EINTR;
-			}
-		}
-
-		if (ret)
-			return ret;
-	}
-
 	multi_lock_write(c, trans);
 
 	if (race_fault()) {
@@ -537,6 +519,36 @@ static inline int do_btree_insert_at(struct btree_insert *trans,
 		}
 	}
 
+	if (likely(!(trans->flags & BTREE_INSERT_JOURNAL_REPLAY))) {
+		u64s = 0;
+		trans_for_each_entry(trans, i)
+			u64s += jset_u64s(i->k->k.u64s);
+
+		ret = bch2_journal_res_get(&c->journal,
+				&trans->journal_res, u64s,
+				JOURNAL_RES_GET_NONBLOCK);
+		if (likely(!ret))
+			goto got_journal_res;
+		if (ret != -EAGAIN)
+			goto out;
+
+		multi_unlock_write(trans);
+		btree_trans_unlock(trans);
+
+		ret = bch2_journal_res_get(&c->journal,
+				&trans->journal_res, u64s,
+				JOURNAL_RES_GET_CHECK);
+		if (ret)
+			return ret;
+
+		if (!btree_trans_relock(trans)) {
+			trans_restart(" (iter relock after journal res get blocked)");
+			return -EINTR;
+		}
+
+		goto retry;
+	}
+got_journal_res:
 	if (!(trans->flags & BTREE_INSERT_JOURNAL_REPLAY)) {
 		if (journal_seq_verify(c))
 			trans_for_each_entry(trans, i)

fs/bcachefs/journal.c

@@ -388,7 +388,8 @@ static int __journal_res_get(struct journal *j, struct journal_res *res,
 		 * freezing:
 		 */
 		trace_journal_full(c);
-		bch2_journal_reclaim_work(&j->reclaim_work.work);
+		if (!(flags & JOURNAL_RES_GET_NONBLOCK))
+			bch2_journal_reclaim_work(&j->reclaim_work.work);
 		ret = -EAGAIN;
 	}