1 files changed, 971 insertions, 0 deletions

diff --git a/fs/bcachefs/super-io.c b/fs/bcachefs/super-io.c
new file mode 100644
index 000000000000..64c2375302a0
--- /dev/null
+++ b/fs/bcachefs/super-io.c
@@ -0,0 +1,971 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "bcachefs.h"
+#include "checksum.h"
+#include "disk_groups.h"
+#include "error.h"
+#include "io.h"
+#include "journal.h"
+#include "replicas.h"
+#include "quota.h"
+#include "super-io.h"
+#include "super.h"
+#include "vstructs.h"
+
+#include <linux/backing-dev.h>
+#include <linux/sort.h>
+
+static const struct blk_holder_ops bch2_sb_handle_bdev_ops = {
+};
+
+const char * const bch2_sb_fields[] = {
+#define x(name, nr)	#name,
+	BCH_SB_FIELDS()
+#undef x
+	NULL
+};
+
+static const char *bch2_sb_field_validate(struct bch_sb *,
+					  struct bch_sb_field *);
+
+struct bch_sb_field *bch2_sb_field_get(struct bch_sb *sb,
+				      enum bch_sb_field_type type)
+{
+	struct bch_sb_field *f;
+
+	/* XXX: need locking around superblock to access optional fields */
+
+	vstruct_for_each(sb, f)
+		if (le32_to_cpu(f->type) == type)
+			return f;
+	return NULL;
+}
+
+static struct bch_sb_field *__bch2_sb_field_resize(struct bch_sb_handle *sb,
+						   struct bch_sb_field *f,
+						   unsigned u64s)
+{
+	unsigned old_u64s = f ? le32_to_cpu(f->u64s) : 0;
+	unsigned sb_u64s = le32_to_cpu(sb->sb->u64s) + u64s - old_u64s;
+
+	BUG_ON(get_order(__vstruct_bytes(struct bch_sb, sb_u64s)) >
+	       sb->page_order);
+
+	if (!f) {
+		f = vstruct_last(sb->sb);
+		memset(f, 0, sizeof(u64) * u64s);
+		f->u64s = cpu_to_le32(u64s);
+		f->type = 0;
+	} else {
+		void *src, *dst;
+
+		src = vstruct_end(f);
+		f->u64s = cpu_to_le32(u64s);
+		dst = vstruct_end(f);
+
+		memmove(dst, src, vstruct_end(sb->sb) - src);
+
+		if (dst > src)
+			memset(src, 0, dst - src);
+	}
+
+	sb->sb->u64s = cpu_to_le32(sb_u64s);
+
+	return f;
+}
+
+/* Superblock realloc/free: */
+
+void bch2_free_super(struct bch_sb_handle *sb)
+{
+	if (sb->bio)
+		kfree(sb->bio);
+	if (!IS_ERR_OR_NULL(sb->bdev))
+		blkdev_put(sb->bdev, sb->holder);
+	kfree(sb->holder);
+
+	free_pages((unsigned long) sb->sb, sb->page_order);
+	memset(sb, 0, sizeof(*sb));
+}
+
+int bch2_sb_realloc(struct bch_sb_handle *sb, unsigned u64s)
+{
+	size_t new_bytes = __vstruct_bytes(struct bch_sb, u64s);
+	unsigned order = get_order(new_bytes);
+	struct bch_sb *new_sb;
+	struct bio *bio;
+
+	if (sb->sb && sb->page_order >= order)
+		return 0;
+
+	if (sb->have_layout) {
+		u64 max_bytes = 512 << sb->sb->layout.sb_max_size_bits;
+
+		if (new_bytes > max_bytes) {
+			pr_err("%pg: superblock too big: want %zu but have %llu",
+			       sb->bdev, new_bytes, max_bytes);
+			return -ENOSPC;
+		}
+	}
+
+	if (sb->page_order >= order && sb->sb)
+		return 0;
+
+	if (dynamic_fault("bcachefs:add:super_realloc"))
+		return -ENOMEM;
+
+	if (sb->have_bio) {
+		unsigned nr_bvecs = 1 << order;
+
+		bio = bio_kmalloc(nr_bvecs, GFP_KERNEL);
+		if (!bio)
+			return -ENOMEM;
+
+		bio_init(bio, NULL, bio->bi_inline_vecs, nr_bvecs, 0);
+
+		if (sb->bio)
+			kfree(sb->bio);
+		sb->bio = bio;
+	}
+
+	new_sb = (void *) __get_free_pages(GFP_KERNEL|__GFP_ZERO, order);
+	if (!new_sb)
+		return -ENOMEM;
+
+	if (sb->sb)
+		memcpy(new_sb, sb->sb, PAGE_SIZE << sb->page_order);
+
+	free_pages((unsigned long) sb->sb, sb->page_order);
+	sb->sb = new_sb;
+
+	sb->page_order = order;
+
+	return 0;
+}
+
+struct bch_sb_field *bch2_sb_field_resize(struct bch_sb_handle *sb,
+					  enum bch_sb_field_type type,
+					  unsigned u64s)
+{
+	struct bch_sb_field *f = bch2_sb_field_get(sb->sb, type);
+	ssize_t old_u64s = f ? le32_to_cpu(f->u64s) : 0;
+	ssize_t d = -old_u64s + u64s;
+
+	if (bch2_sb_realloc(sb, le32_to_cpu(sb->sb->u64s) + d))
+		return NULL;
+
+	if (sb->fs_sb) {
+		struct bch_fs *c = container_of(sb, struct bch_fs, disk_sb);
+		struct bch_dev *ca;
+		unsigned i;
+
+		lockdep_assert_held(&c->sb_lock);
+
+		/* XXX: we're not checking that offline device have enough space */
+
+		for_each_online_member(ca, c, i) {
+			struct bch_sb_handle *sb = &ca->disk_sb;
+
+			if (bch2_sb_realloc(sb, le32_to_cpu(sb->sb->u64s) + d)) {
+				percpu_ref_put(&ca->ref);
+				return NULL;
+			}
+		}
+	}
+
+	f = __bch2_sb_field_resize(sb, f, u64s);
+	f->type = cpu_to_le32(type);
+	return f;
+}
+
+/* Superblock validate: */
+
+static inline void __bch2_sb_layout_size_assert(void)
+{
+	BUILD_BUG_ON(sizeof(struct bch_sb_layout) != 512);
+}
+
+static const char *validate_sb_layout(struct bch_sb_layout *layout)
+{
+	u64 offset, prev_offset, max_sectors;
+	unsigned i;
+
+	if (!uuid_equal(&layout->magic, &BCACHE_MAGIC) &&
+	    !uuid_equal(&layout->magic, &BCHFS_MAGIC))
+		return "Not a bcachefs superblock layout";
+
+	if (layout->layout_type != 0)
+		return "Invalid superblock layout type";
+
+	if (!layout->nr_superblocks)
+		return "Invalid superblock layout: no superblocks";
+
+	if (layout->nr_superblocks > ARRAY_SIZE(layout->sb_offset))
+		return "Invalid superblock layout: too many superblocks";
+
+	max_sectors = 1 << layout->sb_max_size_bits;
+
+	prev_offset = le64_to_cpu(layout->sb_offset[0]);
+
+	for (i = 1; i < layout->nr_superblocks; i++) {
+		offset = le64_to_cpu(layout->sb_offset[i]);
+
+		if (offset < prev_offset + max_sectors)
+			return "Invalid superblock layout: superblocks overlap";
+		prev_offset = offset;
+	}
+
+	return NULL;
+}
+
+const char *bch2_sb_validate(struct bch_sb_handle *disk_sb)
+{
+	struct bch_sb *sb = disk_sb->sb;
+	struct bch_sb_field *f;
+	struct bch_sb_field_members *mi;
+	const char *err;
+	u16 block_size;
+
+	if (le16_to_cpu(sb->version) < BCH_SB_VERSION_MIN ||
+	    le16_to_cpu(sb->version) > BCH_SB_VERSION_MAX)
+		return "Unsupported superblock version";
+
+	if (le16_to_cpu(sb->version) < BCH_SB_VERSION_EXTENT_MAX) {
+		SET_BCH_SB_ENCODED_EXTENT_MAX_BITS(sb, 7);
+		SET_BCH_SB_POSIX_ACL(sb, 1);
+	}
+
+	block_size = le16_to_cpu(sb->block_size);
+
+	if (!is_power_of_2(block_size) ||
+	    block_size > PAGE_SECTORS)
+		return "Bad block size";
+
+	if (bch2_is_zero(sb->user_uuid.b, sizeof(sb->user_uuid)))
+		return "Bad user UUID";
+
+	if (bch2_is_zero(sb->uuid.b, sizeof(sb->uuid)))
+		return "Bad internal UUID";
+
+	if (!sb->nr_devices ||
+	    sb->nr_devices <= sb->dev_idx ||
+	    sb->nr_devices > BCH_SB_MEMBERS_MAX)
+		return "Bad number of member devices";
+
+	if (!BCH_SB_META_REPLICAS_WANT(sb) ||
+	    BCH_SB_META_REPLICAS_WANT(sb) >= BCH_REPLICAS_MAX)
+		return "Invalid number of metadata replicas";
+
+	if (!BCH_SB_META_REPLICAS_REQ(sb) ||
+	    BCH_SB_META_REPLICAS_REQ(sb) >= BCH_REPLICAS_MAX)
+		return "Invalid number of metadata replicas";
+
+	if (!BCH_SB_DATA_REPLICAS_WANT(sb) ||
+	    BCH_SB_DATA_REPLICAS_WANT(sb) >= BCH_REPLICAS_MAX)
+		return "Invalid number of data replicas";
+
+	if (!BCH_SB_DATA_REPLICAS_REQ(sb) ||
+	    BCH_SB_DATA_REPLICAS_REQ(sb) >= BCH_REPLICAS_MAX)
+		return "Invalid number of data replicas";
+
+	if (BCH_SB_META_CSUM_TYPE(sb) >= BCH_CSUM_OPT_NR)
+		return "Invalid metadata checksum type";
+
+	if (BCH_SB_DATA_CSUM_TYPE(sb) >= BCH_CSUM_OPT_NR)
+		return "Invalid metadata checksum type";
+
+	if (BCH_SB_COMPRESSION_TYPE(sb) >= BCH_COMPRESSION_OPT_NR)
+		return "Invalid compression type";
+
+	if (!BCH_SB_BTREE_NODE_SIZE(sb))
+		return "Btree node size not set";
+
+	if (!is_power_of_2(BCH_SB_BTREE_NODE_SIZE(sb)))
+		return "Btree node size not a power of two";
+
+	if (BCH_SB_GC_RESERVE(sb) < 5)
+		return "gc reserve percentage too small";
+
+	if (!sb->time_precision ||
+	    le32_to_cpu(sb->time_precision) > NSEC_PER_SEC)
+		return "invalid time precision";
+
+	/* validate layout */
+	err = validate_sb_layout(&sb->layout);
+	if (err)
+		return err;
+
+	vstruct_for_each(sb, f) {
+		if (!f->u64s)
+			return "Invalid superblock: invalid optional field";
+
+		if (vstruct_next(f) > vstruct_last(sb))
+			return "Invalid superblock: invalid optional field";
+	}
+
+	/* members must be validated first: */
+	mi = bch2_sb_get_members(sb);
+	if (!mi)
+		return "Invalid superblock: member info area missing";
+
+	err = bch2_sb_field_validate(sb, &mi->field);
+	if (err)
+		return err;
+
+	vstruct_for_each(sb, f) {
+		if (le32_to_cpu(f->type) == BCH_SB_FIELD_members)
+			continue;
+
+		err = bch2_sb_field_validate(sb, f);
+		if (err)
+			return err;
+	}
+
+	if (le16_to_cpu(sb->version) < BCH_SB_VERSION_EXTENT_NONCE_V1 &&
+	    bch2_sb_get_crypt(sb) &&
+	    BCH_SB_INITIALIZED(sb))
+		return "Incompatible extent nonces";
+
+	sb->version = cpu_to_le16(BCH_SB_VERSION_MAX);
+
+	return NULL;
+}
+
+/* device open: */
+
+static void bch2_sb_update(struct bch_fs *c)
+{
+	struct bch_sb *src = c->disk_sb.sb;
+	struct bch_sb_field_members *mi = bch2_sb_get_members(src);
+	struct bch_dev *ca;
+	unsigned i;
+
+	lockdep_assert_held(&c->sb_lock);
+
+	c->sb.uuid		= src->uuid;
+	c->sb.user_uuid		= src->user_uuid;
+	c->sb.nr_devices	= src->nr_devices;
+	c->sb.clean		= BCH_SB_CLEAN(src);
+	c->sb.encryption_type	= BCH_SB_ENCRYPTION_TYPE(src);
+	c->sb.encoded_extent_max= 1 << BCH_SB_ENCODED_EXTENT_MAX_BITS(src);
+	c->sb.time_base_lo	= le64_to_cpu(src->time_base_lo);
+	c->sb.time_base_hi	= le32_to_cpu(src->time_base_hi);
+	c->sb.time_precision	= le32_to_cpu(src->time_precision);
+	c->sb.features		= le64_to_cpu(src->features[0]);
+
+	for_each_member_device(ca, c, i)
+		ca->mi = bch2_mi_to_cpu(mi->members + i);
+}
+
+/* doesn't copy member info */
+static void __copy_super(struct bch_sb_handle *dst_handle, struct bch_sb *src)
+{
+	struct bch_sb_field *src_f, *dst_f;
+	struct bch_sb *dst = dst_handle->sb;
+
+	dst->version		= src->version;
+	dst->seq		= src->seq;
+	dst->uuid		= src->uuid;
+	dst->user_uuid		= src->user_uuid;
+	memcpy(dst->label,	src->label, sizeof(dst->label));
+
+	dst->block_size		= src->block_size;
+	dst->nr_devices		= src->nr_devices;
+
+	dst->time_base_lo	= src->time_base_lo;
+	dst->time_base_hi	= src->time_base_hi;
+	dst->time_precision	= src->time_precision;
+
+	memcpy(dst->flags,	src->flags,	sizeof(dst->flags));
+	memcpy(dst->features,	src->features,	sizeof(dst->features));
+	memcpy(dst->compat,	src->compat,	sizeof(dst->compat));
+
+	vstruct_for_each(src, src_f) {
+		if (src_f->type == BCH_SB_FIELD_journal)
+			continue;
+
+		dst_f = bch2_sb_field_get(dst, le32_to_cpu(src_f->type));
+		dst_f = __bch2_sb_field_resize(dst_handle, dst_f,
+					       le32_to_cpu(src_f->u64s));
+
+		memcpy(dst_f, src_f, vstruct_bytes(src_f));
+	}
+}
+
+int bch2_sb_to_fs(struct bch_fs *c, struct bch_sb *src)
+{
+	struct bch_sb_field_journal *journal_buckets =
+		bch2_sb_get_journal(src);
+	unsigned journal_u64s = journal_buckets
+		? le32_to_cpu(journal_buckets->field.u64s)
+		: 0;
+	int ret;
+
+	lockdep_assert_held(&c->sb_lock);
+
+	ret = bch2_sb_realloc(&c->disk_sb,
+			      le32_to_cpu(src->u64s) - journal_u64s);
+	if (ret)
+		return ret;
+
+	__copy_super(&c->disk_sb, src);
+
+	ret = bch2_sb_replicas_to_cpu_replicas(c);
+	if (ret)
+		return ret;
+
+	ret = bch2_sb_disk_groups_to_cpu(c);
+	if (ret)
+		return ret;
+
+	bch2_sb_update(c);
+	return 0;
+}
+
+int bch2_sb_from_fs(struct bch_fs *c, struct bch_dev *ca)
+{
+	struct bch_sb *src = c->disk_sb.sb, *dst = ca->disk_sb.sb;
+	struct bch_sb_field_journal *journal_buckets =
+		bch2_sb_get_journal(dst);
+	unsigned journal_u64s = journal_buckets
+		? le32_to_cpu(journal_buckets->field.u64s)
+		: 0;
+	unsigned u64s = le32_to_cpu(src->u64s) + journal_u64s;
+	int ret;
+
+	ret = bch2_sb_realloc(&ca->disk_sb, u64s);
+	if (ret)
+		return ret;
+
+	__copy_super(&ca->disk_sb, src);
+	return 0;
+}
+
+/* read superblock: */
+
+static const char *read_one_super(struct bch_sb_handle *sb, u64 offset)
+{
+	struct bch_csum csum;
+	size_t bytes;
+reread:
+	bio_reset(sb->bio, sb->bdev, REQ_OP_READ|REQ_SYNC|REQ_META);
+	sb->bio->bi_iter.bi_sector = offset;
+	sb->bio->bi_iter.bi_size = PAGE_SIZE << sb->page_order;
+	bch2_bio_map(sb->bio, sb->sb);
+
+	if (submit_bio_wait(sb->bio))
+		return "IO error";
+
+	if (!uuid_equal(&sb->sb->magic, &BCACHE_MAGIC) &&
+	    !uuid_equal(&sb->sb->magic, &BCHFS_MAGIC))
+		return "Not a bcachefs superblock";
+
+	if (le16_to_cpu(sb->sb->version) < BCH_SB_VERSION_MIN ||
+	    le16_to_cpu(sb->sb->version) > BCH_SB_VERSION_MAX)
+		return "Unsupported superblock version";
+
+	bytes = vstruct_bytes(sb->sb);
+
+	if (bytes > 512 << sb->sb->layout.sb_max_size_bits)
+		return "Bad superblock: too big";
+
+	if (get_order(bytes) > sb->page_order) {
+		if (bch2_sb_realloc(sb, le32_to_cpu(sb->sb->u64s)))
+			return "cannot allocate memory";
+		goto reread;
+	}
+
+	if (BCH_SB_CSUM_TYPE(sb->sb) >= BCH_CSUM_NR)
+		return "unknown csum type";
+
+	/* XXX: verify MACs */
+	csum = csum_vstruct(NULL, BCH_SB_CSUM_TYPE(sb->sb),
+			    null_nonce(), sb->sb);
+
+	if (bch2_crc_cmp(csum, sb->sb->csum))
+		return "bad checksum reading superblock";
+
+	return NULL;
+}
+
+int bch2_read_super(const char *path, struct bch_opts *opts,
+		    struct bch_sb_handle *sb)
+{
+	u64 offset = opt_get(*opts, sb);
+	struct bch_sb_layout layout;
+	const char *err;
+	__le64 *i;
+	int ret;
+
+	pr_verbose_init(*opts, "");
+
+	memset(sb, 0, sizeof(*sb));
+	sb->mode	= BLK_OPEN_READ;
+	sb->have_bio	= true;
+	sb->holder	= kmalloc(1, GFP_KERNEL);
+	if (!sb->holder)
+		return -ENOMEM;
+
+	if (!opt_get(*opts, noexcl))
+		sb->mode |= BLK_OPEN_EXCL;
+
+	if (!opt_get(*opts, nochanges))
+		sb->mode |= BLK_OPEN_WRITE;
+
+	sb->bdev = blkdev_get_by_path(path, sb->mode, sb->holder, &bch2_sb_handle_bdev_ops);
+	if (IS_ERR(sb->bdev) &&
+	    PTR_ERR(sb->bdev) == -EACCES &&
+	    opt_get(*opts, read_only)) {
+		sb->mode &= ~BLK_OPEN_WRITE;
+
+		sb->bdev = blkdev_get_by_path(path, sb->mode, sb->holder, &bch2_sb_handle_bdev_ops);
+		if (!IS_ERR(sb->bdev))
+			opt_set(*opts, nochanges, true);
+	}
+
+	if (IS_ERR(sb->bdev)) {
+		ret = PTR_ERR(sb->bdev);
+		goto out;
+	}
+
+	err = "cannot allocate memory";
+	ret = bch2_sb_realloc(sb, 0);
+	if (ret)
+		goto err;
+
+	ret = -EFAULT;
+	err = "dynamic fault";
+	if (bch2_fs_init_fault("read_super"))
+		goto err;
+
+	ret = -EINVAL;
+	err = read_one_super(sb, offset);
+	if (!err)
+		goto got_super;
+
+	if (opt_defined(*opts, sb))
+		goto err;
+
+	pr_err("error reading default superblock: %s", err);
+
+	/*
+	 * Error reading primary superblock - read location of backup
+	 * superblocks:
+	 */
+	bio_reset(sb->bio, sb->bdev, REQ_OP_READ|REQ_SYNC|REQ_META);
+	sb->bio->bi_iter.bi_sector = BCH_SB_LAYOUT_SECTOR;
+	sb->bio->bi_iter.bi_size = sizeof(struct bch_sb_layout);
+	/*
+	 * use sb buffer to read layout, since sb buffer is page aligned but
+	 * layout won't be:
+	 */
+	bch2_bio_map(sb->bio, sb->sb);
+
+	err = "IO error";
+	if (submit_bio_wait(sb->bio))
+		goto err;
+
+	memcpy(&layout, sb->sb, sizeof(layout));
+	err = validate_sb_layout(&layout);
+	if (err)
+		goto err;
+
+	for (i = layout.sb_offset;
+	     i < layout.sb_offset + layout.nr_superblocks; i++) {
+		offset = le64_to_cpu(*i);
+
+		if (offset == opt_get(*opts, sb))
+			continue;
+
+		err = read_one_super(sb, offset);
+		if (!err)
+			goto got_super;
+	}
+
+	ret = -EINVAL;
+	goto err;
+
+got_super:
+	err = "Superblock block size smaller than device block size";
+	ret = -EINVAL;
+	if (le16_to_cpu(sb->sb->block_size) << 9 <
+	    bdev_logical_block_size(sb->bdev))
+		goto err;
+
+	ret = 0;
+	sb->have_layout = true;
+out:
+	pr_verbose_init(*opts, "ret %i", ret);
+	return ret;
+err:
+	bch2_free_super(sb);
+	pr_err("error reading superblock: %s", err);
+	goto out;
+}
+
+/* write superblock: */
+
+static void write_super_endio(struct bio *bio)
+{
+	struct bch_dev *ca = bio->bi_private;
+
+	/* XXX: return errors directly */
+
+	if (bch2_dev_io_err_on(bio->bi_status, ca, "superblock write"))
+		ca->sb_write_error = 1;
+
+	closure_put(&ca->fs->sb_write);
+	percpu_ref_put(&ca->io_ref);
+}
+
+static void write_one_super(struct bch_fs *c, struct bch_dev *ca, unsigned idx)
+{
+	struct bch_sb *sb = ca->disk_sb.sb;
+	struct bio *bio = ca->disk_sb.bio;
+
+	sb->offset = sb->layout.sb_offset[idx];
+
+	SET_BCH_SB_CSUM_TYPE(sb, c->opts.metadata_checksum);
+	sb->csum = csum_vstruct(c, BCH_SB_CSUM_TYPE(sb),
+				null_nonce(), sb);
+
+	bio_reset(bio, ca->disk_sb.bdev, REQ_OP_WRITE|REQ_SYNC|REQ_META);
+	bio->bi_iter.bi_sector	= le64_to_cpu(sb->offset);
+	bio->bi_iter.bi_size	=
+		roundup((size_t) vstruct_bytes(sb),
+			bdev_logical_block_size(ca->disk_sb.bdev));
+	bio->bi_end_io		= write_super_endio;
+	bio->bi_private		= ca;
+	bch2_bio_map(bio, sb);
+
+	this_cpu_add(ca->io_done->sectors[WRITE][BCH_DATA_SB],
+		     bio_sectors(bio));
+
+	percpu_ref_get(&ca->io_ref);
+	closure_bio_submit(bio, &c->sb_write);
+}
+
+void bch2_write_super(struct bch_fs *c)
+{
+	struct closure *cl = &c->sb_write;
+	struct bch_dev *ca;
+	unsigned i, sb = 0, nr_wrote;
+	const char *err;
+	struct bch_devs_mask sb_written;
+	bool wrote, can_mount_without_written, can_mount_with_written;
+
+	lockdep_assert_held(&c->sb_lock);
+
+	closure_init_stack(cl);
+	memset(&sb_written, 0, sizeof(sb_written));
+
+	le64_add_cpu(&c->disk_sb.sb->seq, 1);
+
+	for_each_online_member(ca, c, i)
+		bch2_sb_from_fs(c, ca);
+
+	for_each_online_member(ca, c, i) {
+		err = bch2_sb_validate(&ca->disk_sb);
+		if (err) {
+			bch2_fs_inconsistent(c, "sb invalid before write: %s", err);
+			goto out;
+		}
+	}
+
+	if (c->opts.nochanges ||
+	    test_bit(BCH_FS_ERROR, &c->flags))
+		goto out;
+
+	for_each_online_member(ca, c, i) {
+		__set_bit(ca->dev_idx, sb_written.d);
+		ca->sb_write_error = 0;
+	}
+
+	do {
+		wrote = false;
+		for_each_online_member(ca, c, i)
+			if (sb < ca->disk_sb.sb->layout.nr_superblocks) {
+				write_one_super(c, ca, sb);
+				wrote = true;
+			}
+		closure_sync(cl);
+		sb++;
+	} while (wrote);
+
+	for_each_online_member(ca, c, i)
+		if (ca->sb_write_error)
+			__clear_bit(ca->dev_idx, sb_written.d);
+
+	nr_wrote = dev_mask_nr(&sb_written);
+
+	can_mount_with_written =
+		bch2_have_enough_devs(__bch2_replicas_status(c, sb_written),
+				      BCH_FORCE_IF_DEGRADED);
+
+	for (i = 0; i < ARRAY_SIZE(sb_written.d); i++)
+		sb_written.d[i] = ~sb_written.d[i];
+
+	can_mount_without_written =
+		bch2_have_enough_devs(__bch2_replicas_status(c, sb_written),
+				      BCH_FORCE_IF_DEGRADED);
+
+	/*
+	 * If we would be able to mount _without_ the devices we successfully
+	 * wrote superblocks to, we weren't able to write to enough devices:
+	 *
+	 * Exception: if we can mount without the successes because we haven't
+	 * written anything (new filesystem), we continue if we'd be able to
+	 * mount with the devices we did successfully write to:
+	 */
+	bch2_fs_fatal_err_on(!nr_wrote ||
+			     (can_mount_without_written &&
+			      !can_mount_with_written), c,
+		"Unable to write superblock to sufficient devices");
+out:
+	/* Make new options visible after they're persistent: */
+	bch2_sb_update(c);
+}
+
+/* BCH_SB_FIELD_journal: */
+
+static int u64_cmp(const void *_l, const void *_r)
+{
+	u64 l = *((const u64 *) _l), r = *((const u64 *) _r);
+
+	return l < r ? -1 : l > r ? 1 : 0;
+}
+
+static const char *bch2_sb_validate_journal(struct bch_sb *sb,
+					    struct bch_sb_field *f)
+{
+	struct bch_sb_field_journal *journal = field_to_type(f, journal);
+	struct bch_member *m = bch2_sb_get_members(sb)->members + sb->dev_idx;
+	const char *err;
+	unsigned nr;
+	unsigned i;
+	u64 *b;
+
+	journal = bch2_sb_get_journal(sb);
+	if (!journal)
+		return NULL;
+
+	nr = bch2_nr_journal_buckets(journal);
+	if (!nr)
+		return NULL;
+
+	b = kmalloc_array(sizeof(u64), nr, GFP_KERNEL);
+	if (!b)
+		return "cannot allocate memory";
+
+	for (i = 0; i < nr; i++)
+		b[i] = le64_to_cpu(journal->buckets[i]);
+
+	sort(b, nr, sizeof(u64), u64_cmp, NULL);
+
+	err = "journal bucket at sector 0";
+	if (!b[0])
+		goto err;
+
+	err = "journal bucket before first bucket";
+	if (m && b[0] < le16_to_cpu(m->first_bucket))
+		goto err;
+
+	err = "journal bucket past end of device";
+	if (m && b[nr - 1] >= le64_to_cpu(m->nbuckets))
+		goto err;
+
+	err = "duplicate journal buckets";
+	for (i = 0; i + 1 < nr; i++)
+		if (b[i] == b[i + 1])
+			goto err;
+
+	err = NULL;
+err:
+	kfree(b);
+	return err;
+}
+
+static const struct bch_sb_field_ops bch_sb_field_ops_journal = {
+	.validate	= bch2_sb_validate_journal,
+};
+
+/* BCH_SB_FIELD_members: */
+
+static const char *bch2_sb_validate_members(struct bch_sb *sb,
+					    struct bch_sb_field *f)
+{
+	struct bch_sb_field_members *mi = field_to_type(f, members);
+	struct bch_member *m;
+
+	if ((void *) (mi->members + sb->nr_devices) >
+	    vstruct_end(&mi->field))
+		return "Invalid superblock: bad member info";
+
+	for (m = mi->members;
+	     m < mi->members + sb->nr_devices;
+	     m++) {
+		if (!bch2_member_exists(m))
+			continue;
+
+		if (le64_to_cpu(m->nbuckets) > LONG_MAX)
+			return "Too many buckets";
+
+		if (le64_to_cpu(m->nbuckets) -
+		    le16_to_cpu(m->first_bucket) < 1 << 10)
+			return "Not enough buckets";
+
+		if (le16_to_cpu(m->bucket_size) <
+		    le16_to_cpu(sb->block_size))
+			return "bucket size smaller than block size";
+
+		if (le16_to_cpu(m->bucket_size) <
+		    BCH_SB_BTREE_NODE_SIZE(sb))
+			return "bucket size smaller than btree node size";
+	}
+
+	if (le16_to_cpu(sb->version) < BCH_SB_VERSION_EXTENT_MAX)
+		for (m = mi->members;
+		     m < mi->members + sb->nr_devices;
+		     m++)
+			SET_BCH_MEMBER_DATA_ALLOWED(m, ~0);
+
+	return NULL;
+}
+
+static const struct bch_sb_field_ops bch_sb_field_ops_members = {
+	.validate	= bch2_sb_validate_members,
+};
+
+/* BCH_SB_FIELD_crypt: */
+
+static const char *bch2_sb_validate_crypt(struct bch_sb *sb,
+					  struct bch_sb_field *f)
+{
+	struct bch_sb_field_crypt *crypt = field_to_type(f, crypt);
+
+	if (vstruct_bytes(&crypt->field) != sizeof(*crypt))
+		return "invalid field crypt: wrong size";
+
+	if (BCH_CRYPT_KDF_TYPE(crypt))
+		return "invalid field crypt: bad kdf type";
+
+	return NULL;
+}
+
+static const struct bch_sb_field_ops bch_sb_field_ops_crypt = {
+	.validate	= bch2_sb_validate_crypt,
+};
+
+/* BCH_SB_FIELD_clean: */
+
+void bch2_fs_mark_clean(struct bch_fs *c, bool clean)
+{
+	struct bch_sb_field_clean *sb_clean;
+	unsigned u64s = sizeof(*sb_clean) / sizeof(u64);
+	struct jset_entry *entry;
+	struct btree_root *r;
+
+	mutex_lock(&c->sb_lock);
+	if (clean == BCH_SB_CLEAN(c->disk_sb.sb))
+		goto out;
+
+	SET_BCH_SB_CLEAN(c->disk_sb.sb, clean);
+
+	if (!clean)
+		goto write_super;
+
+	mutex_lock(&c->btree_root_lock);
+
+	for (r = c->btree_roots;
+	     r < c->btree_roots + BTREE_ID_NR;
+	     r++)
+		if (r->alive)
+			u64s += jset_u64s(r->key.u64s);
+
+	sb_clean = bch2_sb_resize_clean(&c->disk_sb, u64s);
+	if (!sb_clean) {
+		bch_err(c, "error resizing superblock while setting filesystem clean");
+		goto out;
+	}
+
+	sb_clean->flags		= 0;
+	sb_clean->read_clock	= cpu_to_le16(c->bucket_clock[READ].hand);
+	sb_clean->write_clock	= cpu_to_le16(c->bucket_clock[WRITE].hand);
+	sb_clean->journal_seq	= journal_cur_seq(&c->journal) - 1;
+
+	entry = sb_clean->start;
+	memset(entry, 0,
+	       vstruct_end(&sb_clean->field) - (void *) entry);
+
+	for (r = c->btree_roots;
+	     r < c->btree_roots + BTREE_ID_NR;
+	     r++)
+		if (r->alive) {
+			entry->u64s	= r->key.u64s;
+			entry->btree_id	= r - c->btree_roots;
+			entry->level	= r->level;
+			entry->type	= BCH_JSET_ENTRY_btree_root;
+			bkey_copy(&entry->start[0], &r->key);
+			entry = vstruct_next(entry);
+			BUG_ON((void *) entry > vstruct_end(&sb_clean->field));
+		}
+
+	BUG_ON(entry != vstruct_end(&sb_clean->field));
+
+	mutex_unlock(&c->btree_root_lock);
+write_super:
+	bch2_write_super(c);
+out:
+	mutex_unlock(&c->sb_lock);
+}
+
+static const char *bch2_sb_validate_clean(struct bch_sb *sb,
+					  struct bch_sb_field *f)
+{
+	struct bch_sb_field_clean *clean = field_to_type(f, clean);
+
+	if (vstruct_bytes(&clean->field) < sizeof(*clean))
+		return "invalid field crypt: wrong size";
+
+	return NULL;
+}
+
+static const struct bch_sb_field_ops bch_sb_field_ops_clean = {
+	.validate	= bch2_sb_validate_clean,
+};
+
+static const struct bch_sb_field_ops *bch2_sb_field_ops[] = {
+#define x(f, nr)					\
+	[BCH_SB_FIELD_##f] = &bch_sb_field_ops_##f,
+	BCH_SB_FIELDS()
+#undef x
+};
+
+static const char *bch2_sb_field_validate(struct bch_sb *sb,
+					  struct bch_sb_field *f)
+{
+	unsigned type = le32_to_cpu(f->type);
+
+	return type < BCH_SB_FIELD_NR
+		? bch2_sb_field_ops[type]->validate(sb, f)
+		: NULL;
+}
+
+size_t bch2_sb_field_to_text(char *buf, size_t size,
+			     struct bch_sb *sb, struct bch_sb_field *f)
+{
+	unsigned type = le32_to_cpu(f->type);
+	size_t (*to_text)(char *, size_t, struct bch_sb *,
+				   struct bch_sb_field *) =
+		type < BCH_SB_FIELD_NR
+		? bch2_sb_field_ops[type]->to_text
+		: NULL;
+
+	if (!to_text) {
+		if (size)
+			buf[0] = '\0';
+		return 0;
+	}
+
+	return to_text(buf, size, sb, f);
+}