diff --git a/fs/bcachefs/btree_gc.c b/fs/bcachefs/btree_gc.c
index 5091966b7b54..56402fc64bc2 100644
--- a/fs/bcachefs/btree_gc.c
+++ b/fs/bcachefs/btree_gc.c
@@ -605,8 +605,7 @@ static void bch2_gc_done(struct bch_fs *c, bool initial)
 	}
 
 	{
-		unsigned nr = sizeof(struct bch_fs_usage) / sizeof(u64) +
-			c->replicas.nr;
+		unsigned nr = fs_usage_u64s(c);
 		struct bch_fs_usage *dst = (void *)
 			bch2_acc_percpu_u64s((void *) c->usage[0], nr);
 		struct bch_fs_usage *src = (void *)
@@ -657,10 +656,8 @@ static int bch2_gc_start(struct bch_fs *c)
 
 	BUG_ON(c->usage[1]);
 
-	c->usage[1] = __alloc_percpu_gfp(sizeof(struct bch_fs_usage) +
-					 sizeof(u64) * c->replicas.nr,
-					 sizeof(u64),
-					 GFP_KERNEL);
+	c->usage[1] = __alloc_percpu_gfp(fs_usage_u64s(c) * sizeof(u64),
+					 sizeof(u64), GFP_KERNEL);
 	percpu_up_write(&c->mark_lock);
 
 	if (!c->usage[1])
diff --git a/fs/bcachefs/buckets.c b/fs/bcachefs/buckets.c
index ac54d82f9e11..5011e7af3563 100644
--- a/fs/bcachefs/buckets.c
+++ b/fs/bcachefs/buckets.c
@@ -117,11 +117,11 @@ void bch2_bucket_seq_cleanup(struct bch_fs *c)
 void bch2_fs_usage_initialize(struct bch_fs *c)
 {
 	struct bch_fs_usage *usage;
-	unsigned i, nr;
+	unsigned i;
 
 	percpu_down_write(&c->mark_lock);
-	nr = sizeof(struct bch_fs_usage) / sizeof(u64) + c->replicas.nr;
-	usage = (void *) bch2_acc_percpu_u64s((void *) c->usage[0], nr);
+	usage = (void *) bch2_acc_percpu_u64s((void *) c->usage[0],
+					      fs_usage_u64s(c));
 
 	for (i = 0; i < BCH_REPLICAS_MAX; i++)
 		usage->reserved += usage->persistent_reserved[i];
@@ -159,24 +159,23 @@ struct bch_dev_usage bch2_dev_usage_read(struct bch_fs *c, struct bch_dev *ca)
 struct bch_fs_usage *bch2_fs_usage_read(struct bch_fs *c)
 {
 	struct bch_fs_usage *ret;
-	unsigned nr = READ_ONCE(c->replicas.nr);
+	unsigned v, u64s = fs_usage_u64s(c);
 retry:
-	ret = kzalloc(sizeof(*ret) + nr * sizeof(u64), GFP_NOFS);
+	ret = kzalloc(u64s * sizeof(u64), GFP_NOFS);
 	if (unlikely(!ret))
 		return NULL;
 
 	percpu_down_read(&c->mark_lock);
 
-	if (unlikely(nr < c->replicas.nr)) {
-		nr = c->replicas.nr;
+	v = fs_usage_u64s(c);
+	if (unlikely(u64s != v)) {
+		u64s = v;
 		percpu_up_read(&c->mark_lock);
 		kfree(ret);
 		goto retry;
 	}
 
-	acc_u64s_percpu((u64 *) ret,
-			(u64 __percpu *) c->usage[0],
-			sizeof(*ret) / sizeof(u64) + nr);
+	acc_u64s_percpu((u64 *) ret, (u64 __percpu *) c->usage[0], u64s);
 
 	return ret;
 }
@@ -294,8 +293,7 @@ int bch2_fs_usage_apply(struct bch_fs *c,
 
 	preempt_disable();
 	acc_u64s((u64 *) this_cpu_ptr(c->usage[0]),
-		 (u64 *) fs_usage,
-		 sizeof(*fs_usage) / sizeof(u64) + c->replicas.nr);
+		 (u64 *) fs_usage, fs_usage_u64s(c));
 	preempt_enable();
 
 	return ret;
diff --git a/fs/bcachefs/buckets.h b/fs/bcachefs/buckets.h
index 67a1d17610f3..5f0b5a6ec9ad 100644
--- a/fs/bcachefs/buckets.h
+++ b/fs/bcachefs/buckets.h
@@ -212,14 +212,18 @@ static inline u64 dev_buckets_free(struct bch_fs *c, struct bch_dev *ca)
 
 /* Filesystem usage: */
 
+static inline unsigned fs_usage_u64s(struct bch_fs *c)
+{
+
+	return sizeof(struct bch_fs_usage) / sizeof(u64) +
+		READ_ONCE(c->replicas.nr);
+}
+
 static inline struct bch_fs_usage *bch2_fs_usage_get_scratch(struct bch_fs *c)
 {
-	struct bch_fs_usage *ret;
-
-	ret = this_cpu_ptr(c->usage_scratch);
-
-	memset(ret, 0, sizeof(*ret) + c->replicas.nr * sizeof(u64));
+	struct bch_fs_usage *ret = this_cpu_ptr(c->usage_scratch);
 
+	memset(ret, 0, fs_usage_u64s(c) * sizeof(u64));
 	return ret;
 }
 
diff --git a/fs/bcachefs/replicas.c b/fs/bcachefs/replicas.c
index 03bb6b51d15f..72592df9afc0 100644
--- a/fs/bcachefs/replicas.c
+++ b/fs/bcachefs/replicas.c
@@ -262,39 +262,37 @@ static void __replicas_table_update(struct bch_fs_usage __percpu *dst_p,
 static int replicas_table_update(struct bch_fs *c,
 				 struct bch_replicas_cpu *new_r)
 {
-	struct bch_fs_usage __percpu *new_usage[3] = { NULL, NULL, NULL };
+	struct bch_fs_usage __percpu *new_usage[2] = { NULL, NULL };
+	struct bch_fs_usage __percpu *new_scratch = NULL;
 	unsigned bytes = sizeof(struct bch_fs_usage) +
 		sizeof(u64) * new_r->nr;
-	unsigned i;
 	int ret = -ENOMEM;
 
-	for (i = 0; i < 3; i++) {
-		if (i < 2 && !c->usage[i])
-			continue;
+	if (!(new_usage[0] = __alloc_percpu_gfp(bytes, sizeof(u64),
+						GFP_NOIO)) ||
+	    (c->usage[1] &&
+	     !(new_usage[1] = __alloc_percpu_gfp(bytes, sizeof(u64),
+						 GFP_NOIO))) ||
+	    !(new_scratch  = __alloc_percpu_gfp(bytes, sizeof(u64),
+						GFP_NOIO)))
+		goto err;
 
-		new_usage[i] = __alloc_percpu_gfp(bytes, sizeof(u64),
-						  GFP_NOIO);
-		if (!new_usage[i])
-			goto err;
-	}
+	if (c->usage[0])
+		__replicas_table_update(new_usage[0],	new_r,
+					c->usage[0],	&c->replicas);
+	if (c->usage[1])
+		__replicas_table_update(new_usage[1],	new_r,
+					c->usage[1],	&c->replicas);
 
-	for (i = 0; i < 2; i++) {
-		if (!c->usage[i])
-			continue;
-
-		__replicas_table_update(new_usage[i],	new_r,
-					c->usage[i],	&c->replicas);
-
-		swap(c->usage[i], new_usage[i]);
-	}
-
-	swap(c->usage_scratch, new_usage[2]);
-
-	swap(c->replicas, *new_r);
+	swap(c->usage[0],	new_usage[0]);
+	swap(c->usage[1],	new_usage[1]);
+	swap(c->usage_scratch,	new_scratch);
+	swap(c->replicas,	*new_r);
 	ret = 0;
 err:
-	for (i = 0; i < 3; i++)
-		free_percpu(new_usage[i]);
+	free_percpu(new_scratch);
+	free_percpu(new_usage[1]);
+	free_percpu(new_usage[0]);
 	return ret;
 }
 
@@ -975,5 +973,6 @@ int bch2_fs_replicas_init(struct bch_fs *c)
 {
 	c->journal.entry_u64s_reserved +=
 		reserve_journal_replicas(c, &c->replicas);
-	return 0;
+
+	return replicas_table_update(c, &c->replicas);
 }
diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
index 29cb12d841e7..be8c4a604d8c 100644
--- a/fs/bcachefs/super.c
+++ b/fs/bcachefs/super.c
@@ -535,7 +535,7 @@ static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts opts)
 {
 	struct bch_sb_field_members *mi;
 	struct bch_fs *c;
-	unsigned i, iter_size, fs_usage_size;
+	unsigned i, iter_size;
 	const char *err;
 
 	pr_verbose_init(opts, "");
@@ -629,9 +629,6 @@ static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts opts)
 		(btree_blocks(c) + 1) * 2 *
 		sizeof(struct btree_node_iter_set);
 
-	fs_usage_size = sizeof(struct bch_fs_usage) +
-		sizeof(u64) * c->replicas.nr;
-
 	if (!(c->wq = alloc_workqueue("bcachefs",
 				WQ_FREEZABLE|WQ_MEM_RECLAIM|WQ_HIGHPRI, 1)) ||
 	    !(c->copygc_wq = alloc_workqueue("bcache_copygc",
@@ -648,8 +645,6 @@ static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts opts)
 			max(offsetof(struct btree_read_bio, bio),
 			    offsetof(struct btree_write_bio, wbio.bio)),
 			BIOSET_NEED_BVECS) ||
-	    !(c->usage[0] = __alloc_percpu(fs_usage_size, sizeof(u64))) ||
-	    !(c->usage_scratch = __alloc_percpu(fs_usage_size, sizeof(u64))) ||
 	    !(c->pcpu = alloc_percpu(struct bch_fs_pcpu)) ||
 	    mempool_init_kvpmalloc_pool(&c->btree_bounce_pool, 1,
 					btree_bytes(c)) ||