bcachefs: Fixes/improvements for journal entry reservations

This fixes some arithmetic bugs in "bcachefs: Journal updates to dev
usage" - additionally, it cleans things up by switching everything that
goes in every journal entry to the journal_entry_res mechanism.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/bcachefs.h

@@ -582,8 +582,9 @@ struct bch_fs {
 	struct bch_replicas_cpu replicas_gc;
 	struct mutex		replicas_gc_lock;
 
+	struct journal_entry_res btree_root_journal_res;
 	struct journal_entry_res replicas_journal_res;
-
+	struct journal_entry_res clock_journal_res;
 	struct journal_entry_res dev_usage_journal_res;
 
 	struct bch_disk_groups_cpu __rcu *disk_groups;

fs/bcachefs/journal.c

@@ -1119,13 +1119,6 @@ int bch2_fs_journal_init(struct journal *j)
 	j->write_delay_ms	= 1000;
 	j->reclaim_delay_ms	= 100;
 
-	/* Btree roots: */
-	j->entry_u64s_reserved +=
-		BTREE_ID_NR * (JSET_KEYS_U64s + BKEY_BTREE_PTR_U64s_MAX);
-
-	j->entry_u64s_reserved +=
-		2 * (sizeof(struct jset_entry_clock) / sizeof(u64));
-
 	atomic64_set(&j->reservations.counter,
 		((union journal_res_state)
 		 { .cur_entry_offset = JOURNAL_ENTRY_CLOSED_VAL }).v);

fs/bcachefs/replicas.c

@@ -1074,8 +1074,9 @@ unsigned bch2_dev_has_data(struct bch_fs *c, struct bch_dev *ca)
 
 int bch2_fs_replicas_init(struct bch_fs *c)
 {
-	c->journal.entry_u64s_reserved +=
-		reserve_journal_replicas(c, &c->replicas);
+	bch2_journal_entry_res_resize(&c->journal,
+			&c->replicas_journal_res,
+			reserve_journal_replicas(c, &c->replicas));
 
 	return replicas_table_update(c, &c->replicas);
 }

fs/bcachefs/super.c

@@ -159,8 +159,9 @@ static void bch2_dev_usage_journal_reserve(struct bch_fs *c)
 {
 	struct bch_dev *ca;
 	unsigned i, nr = 0, u64s =
-		(sizeof(struct jset_entry_dev_usage) +
-		 sizeof(struct jset_entry_dev_usage_type) * BCH_DATA_NR);
+		((sizeof(struct jset_entry_dev_usage) +
+		  sizeof(struct jset_entry_dev_usage_type) * BCH_DATA_NR)) /
+		sizeof(u64);
 
 	rcu_read_lock();
 	for_each_member_device_rcu(ca, c, i, NULL)
@@ -796,14 +797,20 @@ static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts opts)
 	    bch2_fs_fsio_init(c))
 		goto err;
 
-	bch2_dev_usage_journal_reserve(c);
-
 	mi = bch2_sb_get_members(c->disk_sb.sb);
 	for (i = 0; i < c->sb.nr_devices; i++)
 		if (bch2_dev_exists(c->disk_sb.sb, mi, i) &&
 		    bch2_dev_alloc(c, i))
 			goto err;
 
+	bch2_journal_entry_res_resize(&c->journal,
+			&c->btree_root_journal_res,
+			BTREE_ID_NR * (JSET_KEYS_U64s + BKEY_BTREE_PTR_U64s_MAX));
+	bch2_dev_usage_journal_reserve(c);
+	bch2_journal_entry_res_resize(&c->journal,
+			&c->clock_journal_res,
+			(sizeof(struct jset_entry_clock) / sizeof(u64)) * 2);
+
 	mutex_lock(&bch_fs_list_lock);
 	err = bch2_fs_online(c);
 	mutex_unlock(&bch_fs_list_lock);