bcachefs: New superblock section members_v2

members_v2 has dynamically resizable entries so that we can extend
bch_member. The members can no longer be accessed with simple array
indexing Instead members_v2_get is used to find a member's exact
location within the array and returns a copy of that member.
Alternatively member_v2_get_mut retrieves a mutable point to a member.

Signed-off-by: Hunter Shaffer <huntershaffer182456@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

9 files changed, 326 insertions, 160 deletions

diff --git a/fs/bcachefs/alloc_background.c b/fs/bcachefs/alloc_background.c
index 19ef7a444c23..4059d3d4b7f5 100644
--- a/fs/bcachefs/alloc_background.c
+++ b/fs/bcachefs/alloc_background.c
@@ -1922,7 +1922,7 @@ bkey_err:
 	}
 
 	mutex_lock(&c->sb_lock);
-	m = bch2_sb_get_members(c->disk_sb.sb)->members + ca->dev_idx;
+	m = bch2_members_v2_get_mut(c->disk_sb.sb, ca->dev_idx);
 	SET_BCH_MEMBER_FREESPACE_INITIALIZED(m, true);
 	mutex_unlock(&c->sb_lock);
 
diff --git a/fs/bcachefs/bcachefs_format.h b/fs/bcachefs/bcachefs_format.h
index f0d130440baa..c1a9ba451f04 100644
--- a/fs/bcachefs/bcachefs_format.h
+++ b/fs/bcachefs/bcachefs_format.h
@@ -1231,7 +1231,8 @@ struct bch_sb_field {
 	x(replicas,	7)			\
 	x(journal_seq_blacklist, 8)		\
 	x(journal_v2,	9)			\
-	x(counters,	10)
+	x(counters,	10)			\
+	x(members_v2,	11)
 
 enum bch_sb_field_type {
 #define x(f, nr)	BCH_SB_FIELD_##f = nr,
@@ -1279,6 +1280,8 @@ struct bch_member {
 	__le64			flags[2];
 };
 
+#define BCH_MEMBER_V1_BYTES	56
+
 LE64_BITMASK(BCH_MEMBER_STATE,		struct bch_member, flags[0],  0,  4)
 /* 4-14 unused, was TIER, HAS_(META)DATA, REPLACEMENT */
 LE64_BITMASK(BCH_MEMBER_DISCARD,	struct bch_member, flags[0], 14, 15)
@@ -1308,7 +1311,14 @@ enum bch_member_state {
 
 struct bch_sb_field_members {
 	struct bch_sb_field	field;
-	struct bch_member	members[];
+	struct bch_member	_members[]; //Members are now variable size
+};
+
+struct bch_sb_field_members_v2 {
+	struct bch_sb_field	field;
+	__le16			member_bytes; //size of single member entry
+	u8			pad[6];
+	struct bch_member	_members[];
 };
 
 /* BCH_SB_FIELD_crypt: */
diff --git a/fs/bcachefs/disk_groups.c b/fs/bcachefs/disk_groups.c
index 1bf47a6209dd..43aad8ba8cc9 100644
--- a/fs/bcachefs/disk_groups.c
+++ b/fs/bcachefs/disk_groups.c
@@ -440,7 +440,7 @@ int __bch2_dev_group_set(struct bch_fs *c, struct bch_dev *ca, const char *name)
 	if (ret)
 		return ret;
 
-	mi = &bch2_sb_get_members(c->disk_sb.sb)->members[ca->dev_idx];
+	mi = bch2_members_v2_get_mut(c->disk_sb.sb, ca->dev_idx);
 	SET_BCH_MEMBER_GROUP(mi, v + 1);
 	return 0;
 }
diff --git a/fs/bcachefs/errcode.h b/fs/bcachefs/errcode.h
index 64f7176c2a4e..7cc083776a2e 100644
--- a/fs/bcachefs/errcode.h
+++ b/fs/bcachefs/errcode.h
@@ -91,6 +91,7 @@
 	x(ENOSPC,			ENOSPC_sb_quota)			\
 	x(ENOSPC,			ENOSPC_sb_replicas)			\
 	x(ENOSPC,			ENOSPC_sb_members)			\
+	x(ENOSPC,			ENOSPC_sb_members_v2)			\
 	x(ENOSPC,			ENOSPC_sb_crypt)			\
 	x(ENOSPC,			ENOSPC_btree_slot)			\
 	x(ENOSPC,			ENOSPC_snapshot_tree)			\
diff --git a/fs/bcachefs/sb-members.c b/fs/bcachefs/sb-members.c
index 0be51d082043..bf9c6c60530a 100644
--- a/fs/bcachefs/sb-members.c
+++ b/fs/bcachefs/sb-members.c
@@ -7,9 +7,28 @@
 #include "super-io.h"
 
 /* Code for bch_sb_field_members: */
+
+static struct bch_member *members_v2_get_mut(struct bch_sb_field_members_v2 *mi, int i)
+{
+	return (void *) mi->_members + (i * le16_to_cpu(mi->member_bytes));
+}
+
+struct bch_member *bch2_members_v2_get_mut(struct bch_sb *sb, int i)
+{
+	return members_v2_get_mut(bch2_sb_get_members_v2(sb), i);
+}
+
+static struct bch_member members_v2_get(struct bch_sb_field_members_v2 *mi, int i)
+{
+	struct bch_member ret, *p = members_v2_get_mut(mi, i);
+	memset(&ret, 0, sizeof(ret));
+	memcpy(&ret, p, min_t(size_t, le16_to_cpu(mi->member_bytes), sizeof(ret)));
+	return ret;
+}
+
 static struct bch_member *members_v1_get_mut(struct bch_sb_field_members *mi, int i)
 {
-	return mi->members + i;
+	return (void *) mi->_members + (i * BCH_MEMBER_V1_BYTES);
 }
 
 static struct bch_member members_v1_get(struct bch_sb_field_members *mi, int i)
@@ -21,170 +40,292 @@ static struct bch_member members_v1_get(struct bch_sb_field_members *mi, int i)
 
 struct bch_member bch2_sb_member_get(struct bch_sb *sb, int i)
 {
+	struct bch_sb_field_members_v2 *mi2 = bch2_sb_get_members_v2(sb);
+	if (mi2)
+		return members_v2_get(mi2, i);
 	struct bch_sb_field_members *mi1 = bch2_sb_get_members(sb);
 	return members_v1_get(mi1, i);
 }
 
-static int bch2_sb_members_validate(struct bch_sb *sb,
+static int sb_members_v2_resize_entries(struct bch_fs *c)
+{
+	struct bch_sb_field_members_v2 *mi = bch2_sb_get_members_v2(c->disk_sb.sb);
+
+	if (le16_to_cpu(mi->member_bytes) < sizeof(struct bch_member)) {
+		unsigned u64s = DIV_ROUND_UP((sizeof(*mi) + sizeof(mi->_members[0]) *
+					      c->disk_sb.sb->nr_devices), 8);
+
+		mi = bch2_sb_resize_members_v2(&c->disk_sb, u64s);
+		if (!mi)
+			return -BCH_ERR_ENOSPC_sb_members_v2;
+
+		for (int i = c->disk_sb.sb->nr_devices - 1; i >= 0; --i) {
+			void *dst = (void *) mi->_members + (i * sizeof(struct bch_member));
+			memmove(dst, members_v2_get_mut(mi, i), le16_to_cpu(mi->member_bytes));
+			memset(dst + le16_to_cpu(mi->member_bytes),
+			       0, (sizeof(struct bch_member) - le16_to_cpu(mi->member_bytes)));
+		}
+		mi->member_bytes = cpu_to_le16(sizeof(struct bch_member));
+	}
+	return 0;
+}
+
+int bch2_members_v2_init(struct bch_fs *c)
+{
+	struct bch_sb_field_members *mi1;
+	struct bch_sb_field_members_v2 *mi2;
+
+	if (!bch2_sb_get_members_v2(c->disk_sb.sb)) {
+		mi2 = bch2_sb_resize_members_v2(&c->disk_sb,
+				DIV_ROUND_UP(sizeof(*mi2) +
+					     sizeof(struct bch_member) * c->sb.nr_devices,
+					     sizeof(u64)));
+		mi1 = bch2_sb_get_members(c->disk_sb.sb);
+		memcpy(&mi2->_members[0], &mi1->_members[0],
+		       BCH_MEMBER_V1_BYTES * c->sb.nr_devices);
+		memset(&mi2->pad[0], 0, sizeof(mi2->pad));
+		mi2->member_bytes = cpu_to_le16(BCH_MEMBER_V1_BYTES);
+	}
+
+	return sb_members_v2_resize_entries(c);
+}
+
+int bch_members_cpy_v2_v1(struct bch_sb_handle *disk_sb)
+{
+	struct bch_sb_field_members *mi1;
+	struct bch_sb_field_members_v2 *mi2;
+
+	mi1 = bch2_sb_resize_members(disk_sb,
+			DIV_ROUND_UP(sizeof(*mi1) + BCH_MEMBER_V1_BYTES *
+				     disk_sb->sb->nr_devices, sizeof(u64)));
+	if (!mi1)
+		return -BCH_ERR_ENOSPC_sb_members;
+
+	mi2 = bch2_sb_get_members_v2(disk_sb->sb);
+
+	for (unsigned i = 0; i < disk_sb->sb->nr_devices; i++)
+		memcpy(members_v1_get_mut(mi1, i), members_v2_get_mut(mi2, i), BCH_MEMBER_V1_BYTES);
+
+	return 0;
+}
+
+static int validate_member(struct printbuf *err,
+			   struct bch_member m,
+			   struct bch_sb *sb,
+			   int i)
+{
+	if (le64_to_cpu(m.nbuckets) > LONG_MAX) {
+		prt_printf(err, "device %u: too many buckets (got %llu, max %lu)",
+			   i, le64_to_cpu(m.nbuckets), LONG_MAX);
+		return -BCH_ERR_invalid_sb_members;
+	}
+
+	if (le64_to_cpu(m.nbuckets) -
+	    le16_to_cpu(m.first_bucket) < BCH_MIN_NR_NBUCKETS) {
+		prt_printf(err, "device %u: not enough buckets (got %llu, max %u)",
+			   i, le64_to_cpu(m.nbuckets), BCH_MIN_NR_NBUCKETS);
+		return -BCH_ERR_invalid_sb_members;
+	}
+
+	if (le16_to_cpu(m.bucket_size) <
+	    le16_to_cpu(sb->block_size)) {
+		prt_printf(err, "device %u: bucket size %u smaller than block size %u",
+			   i, le16_to_cpu(m.bucket_size), le16_to_cpu(sb->block_size));
+		return -BCH_ERR_invalid_sb_members;
+	}
+
+	if (le16_to_cpu(m.bucket_size) <
+	    BCH_SB_BTREE_NODE_SIZE(sb)) {
+		prt_printf(err, "device %u: bucket size %u smaller than btree node size %llu",
+			   i, le16_to_cpu(m.bucket_size), BCH_SB_BTREE_NODE_SIZE(sb));
+		return -BCH_ERR_invalid_sb_members;
+	}
+
+	return 0;
+}
+
+static void member_to_text(struct printbuf *out,
+			   struct bch_member m,
+			   struct bch_sb_field_disk_groups *gi,
+			   struct bch_sb *sb,
+			   int i)
+{
+	unsigned data_have = bch2_sb_dev_has_data(sb, i);
+	u64 bucket_size = le16_to_cpu(m.bucket_size);
+	u64 device_size = le64_to_cpu(m.nbuckets) * bucket_size;
+
+
+	prt_printf(out, "Device:");
+	prt_tab(out);
+	prt_printf(out, "%u", i);
+	prt_newline(out);
+
+	printbuf_indent_add(out, 2);
+
+	prt_printf(out, "UUID:");
+	prt_tab(out);
+	pr_uuid(out, m.uuid.b);
+	prt_newline(out);
+
+	prt_printf(out, "Size:");
+	prt_tab(out);
+	prt_units_u64(out, device_size << 9);
+	prt_newline(out);
+
+	prt_printf(out, "Bucket size:");
+	prt_tab(out);
+	prt_units_u64(out, bucket_size << 9);
+	prt_newline(out);
+
+	prt_printf(out, "First bucket:");
+	prt_tab(out);
+	prt_printf(out, "%u", le16_to_cpu(m.first_bucket));
+	prt_newline(out);
+
+	prt_printf(out, "Buckets:");
+	prt_tab(out);
+	prt_printf(out, "%llu", le64_to_cpu(m.nbuckets));
+	prt_newline(out);
+
+	prt_printf(out, "Last mount:");
+	prt_tab(out);
+	if (m.last_mount)
+		pr_time(out, le64_to_cpu(m.last_mount));
+	else
+		prt_printf(out, "(never)");
+	prt_newline(out);
+
+	prt_printf(out, "State:");
+	prt_tab(out);
+	prt_printf(out, "%s",
+		   BCH_MEMBER_STATE(&m) < BCH_MEMBER_STATE_NR
+		   ? bch2_member_states[BCH_MEMBER_STATE(&m)]
+		   : "unknown");
+	prt_newline(out);
+
+	prt_printf(out, "Label:");
+	prt_tab(out);
+	if (BCH_MEMBER_GROUP(&m)) {
+		unsigned idx = BCH_MEMBER_GROUP(&m) - 1;
+
+		if (idx < disk_groups_nr(gi))
+			prt_printf(out, "%s (%u)",
+				   gi->entries[idx].label, idx);
+		else
+			prt_printf(out, "(bad disk labels section)");
+	} else {
+		prt_printf(out, "(none)");
+	}
+	prt_newline(out);
+
+	prt_printf(out, "Data allowed:");
+	prt_tab(out);
+	if (BCH_MEMBER_DATA_ALLOWED(&m))
+		prt_bitflags(out, bch2_data_types, BCH_MEMBER_DATA_ALLOWED(&m));
+	else
+		prt_printf(out, "(none)");
+	prt_newline(out);
+
+	prt_printf(out, "Has data:");
+	prt_tab(out);
+	if (data_have)
+		prt_bitflags(out, bch2_data_types, data_have);
+	else
+		prt_printf(out, "(none)");
+	prt_newline(out);
+
+	prt_printf(out, "Discard:");
+	prt_tab(out);
+	prt_printf(out, "%llu", BCH_MEMBER_DISCARD(&m));
+	prt_newline(out);
+
+	prt_printf(out, "Freespace initialized:");
+	prt_tab(out);
+	prt_printf(out, "%llu", BCH_MEMBER_FREESPACE_INITIALIZED(&m));
+	prt_newline(out);
+
+	printbuf_indent_sub(out, 2);
+}
+
+static int bch2_sb_members_v1_validate(struct bch_sb *sb,
 				    struct bch_sb_field *f,
 				    struct printbuf *err)
 {
 	struct bch_sb_field_members *mi = field_to_type(f, members);
 	unsigned i;
 
-	if ((void *) (mi->members + sb->nr_devices) >
+	if ((void *) members_v1_get_mut(mi, sb->nr_devices)  >
 	    vstruct_end(&mi->field)) {
 		prt_printf(err, "too many devices for section size");
 		return -BCH_ERR_invalid_sb_members;
 	}
 
 	for (i = 0; i < sb->nr_devices; i++) {
-		struct bch_member *m = mi->members + i;
-
-		if (!bch2_member_exists(m))
-			continue;
-
-		if (le64_to_cpu(m->nbuckets) > LONG_MAX) {
-			prt_printf(err, "device %u: too many buckets (got %llu, max %lu)",
-			       i, le64_to_cpu(m->nbuckets), LONG_MAX);
-			return -BCH_ERR_invalid_sb_members;
-		}
-
-		if (le64_to_cpu(m->nbuckets) -
-		    le16_to_cpu(m->first_bucket) < BCH_MIN_NR_NBUCKETS) {
-			prt_printf(err, "device %u: not enough buckets (got %llu, max %u)",
-			       i, le64_to_cpu(m->nbuckets), BCH_MIN_NR_NBUCKETS);
-			return -BCH_ERR_invalid_sb_members;
-		}
-
-		if (le16_to_cpu(m->bucket_size) <
-		    le16_to_cpu(sb->block_size)) {
-			prt_printf(err, "device %u: bucket size %u smaller than block size %u",
-			       i, le16_to_cpu(m->bucket_size), le16_to_cpu(sb->block_size));
-			return -BCH_ERR_invalid_sb_members;
-		}
+		struct bch_member m = members_v1_get(mi, i);
 
-		if (le16_to_cpu(m->bucket_size) <
-		    BCH_SB_BTREE_NODE_SIZE(sb)) {
-			prt_printf(err, "device %u: bucket size %u smaller than btree node size %llu",
-			       i, le16_to_cpu(m->bucket_size), BCH_SB_BTREE_NODE_SIZE(sb));
-			return -BCH_ERR_invalid_sb_members;
-		}
+		int ret = validate_member(err, m, sb, i);
+		if (ret)
+			return ret;
 	}
 
 	return 0;
 }
 
-static void bch2_sb_members_to_text(struct printbuf *out, struct bch_sb *sb,
-				    struct bch_sb_field *f)
+static void bch2_sb_members_v1_to_text(struct printbuf *out, struct bch_sb *sb,
+				       struct bch_sb_field *f)
 {
 	struct bch_sb_field_members *mi = field_to_type(f, members);
 	struct bch_sb_field_disk_groups *gi = bch2_sb_get_disk_groups(sb);
 	unsigned i;
 
 	for (i = 0; i < sb->nr_devices; i++) {
-		struct bch_member *m = mi->members + i;
-		unsigned data_have = bch2_sb_dev_has_data(sb, i);
-		u64 bucket_size = le16_to_cpu(m->bucket_size);
-		u64 device_size = le64_to_cpu(m->nbuckets) * bucket_size;
-
-		if (!bch2_member_exists(m))
-			continue;
-
-		prt_printf(out, "Device:");
-		prt_tab(out);
-		prt_printf(out, "%u", i);
-		prt_newline(out);
-
-		printbuf_indent_add(out, 2);
-
-		prt_printf(out, "UUID:");
-		prt_tab(out);
-		pr_uuid(out, m->uuid.b);
-		prt_newline(out);
-
-		prt_printf(out, "Size:");
-		prt_tab(out);
-		prt_units_u64(out, device_size << 9);
-		prt_newline(out);
-
-		prt_printf(out, "Bucket size:");
-		prt_tab(out);
-		prt_units_u64(out, bucket_size << 9);
-		prt_newline(out);
-
-		prt_printf(out, "First bucket:");
-		prt_tab(out);
-		prt_printf(out, "%u", le16_to_cpu(m->first_bucket));
-		prt_newline(out);
-
-		prt_printf(out, "Buckets:");
-		prt_tab(out);
-		prt_printf(out, "%llu", le64_to_cpu(m->nbuckets));
-		prt_newline(out);
-
-		prt_printf(out, "Last mount:");
-		prt_tab(out);
-		if (m->last_mount)
-			pr_time(out, le64_to_cpu(m->last_mount));
-		else
-			prt_printf(out, "(never)");
-		prt_newline(out);
-
-		prt_printf(out, "State:");
-		prt_tab(out);
-		prt_printf(out, "%s",
-		       BCH_MEMBER_STATE(m) < BCH_MEMBER_STATE_NR
-		       ? bch2_member_states[BCH_MEMBER_STATE(m)]
-		       : "unknown");
-		prt_newline(out);
-
-		prt_printf(out, "Label:");
-		prt_tab(out);
-		if (BCH_MEMBER_GROUP(m)) {
-			unsigned idx = BCH_MEMBER_GROUP(m) - 1;
-
-			if (idx < disk_groups_nr(gi))
-				prt_printf(out, "%s (%u)",
-				       gi->entries[idx].label, idx);
-			else
-				prt_printf(out, "(bad disk labels section)");
-		} else {
-			prt_printf(out, "(none)");
-		}
-		prt_newline(out);
+		struct bch_member m = members_v1_get(mi, i);
+		member_to_text(out, m, gi, sb, i);
+	}
+}
 
-		prt_printf(out, "Data allowed:");
-		prt_tab(out);
-		if (BCH_MEMBER_DATA_ALLOWED(m))
-			prt_bitflags(out, bch2_data_types, BCH_MEMBER_DATA_ALLOWED(m));
-		else
-			prt_printf(out, "(none)");
-		prt_newline(out);
+const struct bch_sb_field_ops bch_sb_field_ops_members = {
+	.validate	= bch2_sb_members_v1_validate,
+	.to_text	= bch2_sb_members_v1_to_text,
+};
 
-		prt_printf(out, "Has data:");
-		prt_tab(out);
-		if (data_have)
-			prt_bitflags(out, bch2_data_types, data_have);
-		else
-			prt_printf(out, "(none)");
-		prt_newline(out);
+static void bch2_sb_members_v2_to_text(struct printbuf *out, struct bch_sb *sb,
+				       struct bch_sb_field *f)
+{
+	struct bch_sb_field_members_v2 *mi = field_to_type(f, members_v2);
+	struct bch_sb_field_disk_groups *gi = bch2_sb_get_disk_groups(sb);
+	unsigned i;
 
-		prt_printf(out, "Discard:");
-		prt_tab(out);
-		prt_printf(out, "%llu", BCH_MEMBER_DISCARD(m));
-		prt_newline(out);
+	for (i = 0; i < sb->nr_devices; i++) {
+		struct bch_member m = members_v2_get(mi, i);
+		member_to_text(out, m, gi, sb, i);
+	}
+}
+
+static int bch2_sb_members_v2_validate(struct bch_sb *sb,
+				       struct bch_sb_field *f,
+				       struct printbuf *err)
+{
+	struct bch_sb_field_members_v2 *mi = field_to_type(f, members_v2);
+	size_t mi_bytes = (void *) members_v2_get_mut(mi, sb->nr_devices) -
+		(void *) mi;
 
-		prt_printf(out, "Freespace initialized:");
-		prt_tab(out);
-		prt_printf(out, "%llu", BCH_MEMBER_FREESPACE_INITIALIZED(m));
-		prt_newline(out);
+	if (mi_bytes > vstruct_bytes(&mi->field)) {
+		prt_printf(err, "section too small (%zu > %zu)",
+			   mi_bytes, vstruct_bytes(&mi->field));
+		return -BCH_ERR_invalid_sb_members;
+	}
 
-		printbuf_indent_sub(out, 2);
+	for (unsigned i = 0; i < sb->nr_devices; i++) {
+		int ret = validate_member(err, members_v2_get(mi, i), sb, i);
+		if (ret)
+			return ret;
 	}
+
+	return 0;
 }
 
-const struct bch_sb_field_ops bch_sb_field_ops_members = {
-	.validate	= bch2_sb_members_validate,
-	.to_text	= bch2_sb_members_to_text,
+const struct bch_sb_field_ops bch_sb_field_ops_members_v2 = {
+	.validate	= bch2_sb_members_v2_validate,
+	.to_text	= bch2_sb_members_v2_to_text,
 };
diff --git a/fs/bcachefs/sb-members.h b/fs/bcachefs/sb-members.h
index 85d1af6a990c..72958facbb4f 100644
--- a/fs/bcachefs/sb-members.h
+++ b/fs/bcachefs/sb-members.h
@@ -2,6 +2,9 @@
 #ifndef _BCACHEFS_SB_MEMBERS_H
 #define _BCACHEFS_SB_MEMBERS_H
 
+int bch2_members_v2_init(struct bch_fs *c);
+int bch_members_cpy_v2_v1(struct bch_sb_handle *disk_sb);
+struct bch_member *bch2_members_v2_get_mut(struct bch_sb *sb, int i);
 struct bch_member bch2_sb_member_get(struct bch_sb *sb, int i);
 
 static inline bool bch2_dev_is_online(struct bch_dev *ca)
@@ -173,6 +176,8 @@ static inline struct bch_devs_mask bch2_online_devs(struct bch_fs *c)
 	return devs;
 }
 
+extern const struct bch_sb_field_ops bch_sb_field_ops_members_v2;
+
 extern const struct bch_sb_field_ops bch_sb_field_ops_members;
 
 #endif /* _BCACHEFS_SB_MEMBERS_H */
diff --git a/fs/bcachefs/super-io.c b/fs/bcachefs/super-io.c
index 16e3a8aa290d..8bb9c9a67fe5 100644
--- a/fs/bcachefs/super-io.c
+++ b/fs/bcachefs/super-io.c
@@ -892,6 +892,7 @@ int bch2_write_super(struct bch_fs *c)
 	SET_BCH_SB_BIG_ENDIAN(c->disk_sb.sb, CPU_BIG_ENDIAN);
 
 	bch2_sb_counters_from_cpu(c);
+	bch_members_cpy_v2_v1(&c->disk_sb);
 
 	for_each_online_member(ca, c, i)
 		bch2_sb_from_fs(c, ca);
diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
index 7ba1ebabc176..c91c3f7e3328 100644
--- a/fs/bcachefs/super.c
+++ b/fs/bcachefs/super.c
@@ -400,6 +400,10 @@ static int __bch2_fs_read_write(struct bch_fs *c, bool early)
 
 	bch_info(c, "going read-write");
 
+	ret = bch2_members_v2_init(c);
+	if (ret)
+		goto err;
+
 	ret = bch2_fs_mark_dirty(c);
 	if (ret)
 		goto err;
@@ -924,7 +928,6 @@ static void print_mount_opts(struct bch_fs *c)
 
 int bch2_fs_start(struct bch_fs *c)
 {
-	struct bch_sb_field_members *mi;
 	struct bch_dev *ca;
 	time64_t now = ktime_get_real_seconds();
 	unsigned i;
@@ -938,12 +941,17 @@ int bch2_fs_start(struct bch_fs *c)
 
 	mutex_lock(&c->sb_lock);
 
+	ret = bch2_members_v2_init(c);
+	if (ret) {
+		mutex_unlock(&c->sb_lock);
+		goto err;
+	}
+
 	for_each_online_member(ca, c, i)
 		bch2_sb_from_fs(c, ca);
 
-	mi = bch2_sb_get_members(c->disk_sb.sb);
 	for_each_online_member(ca, c, i)
-		mi->members[ca->dev_idx].last_mount = cpu_to_le64(now);
+		bch2_members_v2_get_mut(c->disk_sb.sb, i)->last_mount = cpu_to_le64(now);
 
 	mutex_unlock(&c->sb_lock);
 
@@ -1382,7 +1390,7 @@ static void __bch2_dev_read_write(struct bch_fs *c, struct bch_dev *ca)
 int __bch2_dev_set_state(struct bch_fs *c, struct bch_dev *ca,
 			 enum bch_member_state new_state, int flags)
 {
-	struct bch_sb_field_members *mi;
+	struct bch_member *m;
 	int ret = 0;
 
 	if (ca->mi.state == new_state)
@@ -1397,8 +1405,8 @@ int __bch2_dev_set_state(struct bch_fs *c, struct bch_dev *ca,
 	bch_notice(ca, "%s", bch2_member_states[new_state]);
 
 	mutex_lock(&c->sb_lock);
-	mi = bch2_sb_get_members(c->disk_sb.sb);
-	SET_BCH_MEMBER_STATE(&mi->members[ca->dev_idx], new_state);
+	m = bch2_members_v2_get_mut(c->disk_sb.sb, ca->dev_idx);
+	SET_BCH_MEMBER_STATE(m, new_state);
 	bch2_write_super(c);
 	mutex_unlock(&c->sb_lock);
 
@@ -1454,7 +1462,7 @@ static int bch2_dev_remove_alloc(struct bch_fs *c, struct bch_dev *ca)
 
 int bch2_dev_remove(struct bch_fs *c, struct bch_dev *ca, int flags)
 {
-	struct bch_sb_field_members *mi;
+	struct bch_member *m;
 	unsigned dev_idx = ca->dev_idx, data;
 	int ret;
 
@@ -1542,8 +1550,8 @@ int bch2_dev_remove(struct bch_fs *c, struct bch_dev *ca, int flags)
 	 * this device must be gone:
 	 */
 	mutex_lock(&c->sb_lock);
-	mi = bch2_sb_get_members(c->disk_sb.sb);
-	memset(&mi->members[dev_idx].uuid, 0, sizeof(mi->members[dev_idx].uuid));
+	m = bch2_members_v2_get_mut(c->disk_sb.sb, dev_idx);
+	memset(&m->uuid, 0, sizeof(m->uuid));
 
 	bch2_write_super(c);
 
@@ -1566,7 +1574,7 @@ int bch2_dev_add(struct bch_fs *c, const char *path)
 	struct bch_opts opts = bch2_opts_empty();
 	struct bch_sb_handle sb;
 	struct bch_dev *ca = NULL;
-	struct bch_sb_field_members *mi;
+	struct bch_sb_field_members_v2 *mi;
 	struct bch_member dev_mi;
 	unsigned dev_idx, nr_devices, u64s;
 	struct printbuf errbuf = PRINTBUF;
@@ -1622,9 +1630,9 @@ int bch2_dev_add(struct bch_fs *c, const char *path)
 		goto err_unlock;
 	}
 
-	mi = bch2_sb_get_members(ca->disk_sb.sb);
+	mi = bch2_sb_get_members_v2(ca->disk_sb.sb);
 
-	if (!bch2_sb_resize_members(&ca->disk_sb,
+	if (!bch2_sb_resize_members_v2(&ca->disk_sb,
 				le32_to_cpu(mi->field.u64s) +
 				sizeof(dev_mi) / sizeof(u64))) {
 		ret = -BCH_ERR_ENOSPC_sb_members;
@@ -1645,20 +1653,21 @@ no_slot:
 
 have_slot:
 	nr_devices = max_t(unsigned, dev_idx + 1, c->sb.nr_devices);
-	u64s = (sizeof(struct bch_sb_field_members) +
-		sizeof(struct bch_member) * nr_devices) / sizeof(u64);
+	u64s = DIV_ROUND_UP(sizeof(struct bch_sb_field_members_v2) +
+			    le16_to_cpu(mi->member_bytes) * nr_devices, sizeof(u64));
 
-	mi = bch2_sb_resize_members(&c->disk_sb, u64s);
+	mi = bch2_sb_resize_members_v2(&c->disk_sb, u64s);
 	if (!mi) {
 		ret = -BCH_ERR_ENOSPC_sb_members;
 		bch_err_msg(c, ret, "setting up new superblock");
 		goto err_unlock;
 	}
+	struct bch_member *m = bch2_members_v2_get_mut(c->disk_sb.sb, dev_idx);
 
 	/* success: */
 
-	mi->members[dev_idx] = dev_mi;
-	mi->members[dev_idx].last_mount = cpu_to_le64(ktime_get_real_seconds());
+	*m = dev_mi;
+	m->last_mount = cpu_to_le64(ktime_get_real_seconds());
 	c->disk_sb.sb->nr_devices	= nr_devices;
 
 	ca->disk_sb.sb->dev_idx	= dev_idx;
@@ -1718,7 +1727,6 @@ int bch2_dev_online(struct bch_fs *c, const char *path)
 {
 	struct bch_opts opts = bch2_opts_empty();
 	struct bch_sb_handle sb = { NULL };
-	struct bch_sb_field_members *mi;
 	struct bch_dev *ca;
 	unsigned dev_idx;
 	int ret;
@@ -1755,9 +1763,9 @@ int bch2_dev_online(struct bch_fs *c, const char *path)
 		__bch2_dev_read_write(c, ca);
 
 	mutex_lock(&c->sb_lock);
-	mi = bch2_sb_get_members(c->disk_sb.sb);
+	struct bch_member *m = bch2_members_v2_get_mut(c->disk_sb.sb, ca->dev_idx);
 
-	mi->members[ca->dev_idx].last_mount =
+	m->last_mount =
 		cpu_to_le64(ktime_get_real_seconds());
 
 	bch2_write_super(c);
@@ -1799,7 +1807,7 @@ int bch2_dev_offline(struct bch_fs *c, struct bch_dev *ca, int flags)
 
 int bch2_dev_resize(struct bch_fs *c, struct bch_dev *ca, u64 nbuckets)
 {
-	struct bch_member *mi;
+	struct bch_member *m;
 	int ret = 0;
 
 	down_write(&c->state_lock);
@@ -1829,8 +1837,8 @@ int bch2_dev_resize(struct bch_fs *c, struct bch_dev *ca, u64 nbuckets)
 		goto err;
 
 	mutex_lock(&c->sb_lock);
-	mi = &bch2_sb_get_members(c->disk_sb.sb)->members[ca->dev_idx];
-	mi->nbuckets = cpu_to_le64(nbuckets);
+	m = bch2_members_v2_get_mut(c->disk_sb.sb, ca->dev_idx);
+	m->nbuckets = cpu_to_le64(nbuckets);
 
 	bch2_write_super(c);
 	mutex_unlock(&c->sb_lock);
diff --git a/fs/bcachefs/sysfs.c b/fs/bcachefs/sysfs.c
index b700be5b6664..eb764b9a4629 100644
--- a/fs/bcachefs/sysfs.c
+++ b/fs/bcachefs/sysfs.c
@@ -962,7 +962,7 @@ STORE(bch2_dev)
 		bool v = strtoul_or_return(buf);
 
 		mutex_lock(&c->sb_lock);
-		mi = &bch2_sb_get_members(c->disk_sb.sb)->members[ca->dev_idx];
+		mi = bch2_members_v2_get_mut(c->disk_sb.sb, ca->dev_idx);
 
 		if (v != BCH_MEMBER_DISCARD(mi)) {
 			SET_BCH_MEMBER_DISCARD(mi, v);
@@ -975,7 +975,7 @@ STORE(bch2_dev)
 		u64 v = strtoul_or_return(buf);
 
 		mutex_lock(&c->sb_lock);
-		mi = &bch2_sb_get_members(c->disk_sb.sb)->members[ca->dev_idx];
+		mi = bch2_members_v2_get_mut(c->disk_sb.sb, ca->dev_idx);
 
 		if (v + 1 != BCH_MEMBER_DURABILITY(mi)) {
 			SET_BCH_MEMBER_DURABILITY(mi, v + 1);