linux/fs/bcachefs/sb-downgrade.c

// SPDX-License-Identifier: GPL-2.0

/*
 * Superblock section that contains a list of recovery passes to run when
 * downgrading past a given version
 */

#include "bcachefs.h"
#include "darray.h"
#include "recovery.h"
#include "sb-downgrade.h"
#include "sb-errors.h"
#include "super-io.h"

/*
 * Downgrade table:
 * When dowgrading past certain versions, we need to run certain recovery passes
 * and fix certain errors:
 *
 * x(version, recovery_passes, errors...)
 */

#define DOWNGRADE_TABLE()

struct downgrade_entry {
	u64		recovery_passes;
	u16		version;
	u16		nr_errors;
	const u16	*errors;
};

#define x(ver, passes, ...) static const u16 ver_##errors[] = { __VA_ARGS__ };
DOWNGRADE_TABLE()
#undef x

static const struct downgrade_entry downgrade_table[] = {
#define x(ver, passes, ...) {					\
	.recovery_passes	= passes,			\
	.version		= bcachefs_metadata_version_##ver,\
	.nr_errors		= ARRAY_SIZE(ver_##errors),	\
	.errors			= ver_##errors,			\
},
DOWNGRADE_TABLE()
#undef x
};

static inline const struct bch_sb_field_downgrade_entry *
downgrade_entry_next_c(const struct bch_sb_field_downgrade_entry *e)
{
	return (void *) &e->errors[le16_to_cpu(e->nr_errors)];
}

#define for_each_downgrade_entry(_d, _i)						\
	for (const struct bch_sb_field_downgrade_entry *_i = (_d)->entries;		\
	     (void *) _i	< vstruct_end(&(_d)->field) &&				\
	     (void *) &_i->errors[0] < vstruct_end(&(_d)->field);			\
	     _i = downgrade_entry_next_c(_i))

static int bch2_sb_downgrade_validate(struct bch_sb *sb, struct bch_sb_field *f,
				      struct printbuf *err)
{
	struct bch_sb_field_downgrade *e = field_to_type(f, downgrade);

	for_each_downgrade_entry(e, i) {
		if (BCH_VERSION_MAJOR(le16_to_cpu(i->version)) !=
		    BCH_VERSION_MAJOR(le16_to_cpu(sb->version))) {
			prt_printf(err, "downgrade entry with mismatched major version (%u != %u)",
				   BCH_VERSION_MAJOR(le16_to_cpu(i->version)),
				   BCH_VERSION_MAJOR(le16_to_cpu(sb->version)));
			return -BCH_ERR_invalid_sb_downgrade;
		}
	}

	return 0;
}

static void bch2_sb_downgrade_to_text(struct printbuf *out, struct bch_sb *sb,
				      struct bch_sb_field *f)
{
	struct bch_sb_field_downgrade *e = field_to_type(f, downgrade);

	if (out->nr_tabstops <= 1)
		printbuf_tabstop_push(out, 16);

	for_each_downgrade_entry(e, i) {
		prt_str(out, "version:");
		prt_tab(out);
		bch2_version_to_text(out, le16_to_cpu(i->version));
		prt_newline(out);

		prt_str(out, "recovery passes:");
		prt_tab(out);
		prt_bitflags(out, bch2_recovery_passes,
			     bch2_recovery_passes_from_stable(le64_to_cpu(i->recovery_passes[0])));
		prt_newline(out);

		prt_str(out, "errors:");
		prt_tab(out);
		bool first = true;
		for (unsigned j = 0; j < le16_to_cpu(i->nr_errors); j++) {
			if (!first)
				prt_char(out, ',');
			first = false;
			unsigned e = le16_to_cpu(i->errors[j]);
			prt_str(out, e < BCH_SB_ERR_MAX ? bch2_sb_error_strs[e] : "(unknown)");
		}
		prt_newline(out);
	}
}

const struct bch_sb_field_ops bch_sb_field_ops_downgrade = {
	.validate	= bch2_sb_downgrade_validate,
	.to_text	= bch2_sb_downgrade_to_text,
};

int bch2_sb_downgrade_update(struct bch_fs *c)
{
	darray_char table = {};
	int ret = 0;

	for (const struct downgrade_entry *src = downgrade_table;
	     src < downgrade_table + ARRAY_SIZE(downgrade_table);
	     src++) {
		if (BCH_VERSION_MAJOR(src->version) != BCH_VERSION_MAJOR(le16_to_cpu(c->disk_sb.sb->version)))
			continue;

		struct bch_sb_field_downgrade_entry *dst;
		unsigned bytes = sizeof(*dst) + sizeof(dst->errors[0]) * src->nr_errors;

		ret = darray_make_room(&table, bytes);
		if (ret)
			goto out;

		dst = (void *) &darray_top(table);
		dst->version = cpu_to_le16(src->version);
		dst->recovery_passes[0]	= cpu_to_le64(src->recovery_passes);
		dst->recovery_passes[1]	= 0;
		dst->nr_errors		= cpu_to_le16(src->nr_errors);
		for (unsigned i = 0; i < src->nr_errors; i++)
			dst->errors[i] = cpu_to_le16(src->errors[i]);

		table.nr += bytes;
	}

	struct bch_sb_field_downgrade *d = bch2_sb_field_get(c->disk_sb.sb, downgrade);

	unsigned sb_u64s = DIV_ROUND_UP(sizeof(*d) + table.nr, sizeof(u64));

	if (d && le32_to_cpu(d->field.u64s) > sb_u64s)
		goto out;

	d = bch2_sb_field_resize(&c->disk_sb, downgrade, sb_u64s);
	if (!d) {
		ret = -BCH_ERR_ENOSPC_sb_downgrade;
		goto out;
	}

	memcpy(d->entries, table.data, table.nr);
	memset_u64s_tail(d->entries, 0, table.nr);
out:
	darray_exit(&table);
	return ret;
}

void bch2_sb_set_downgrade(struct bch_fs *c, unsigned new_minor, unsigned old_minor)
{
	struct bch_sb_field_downgrade *d = bch2_sb_field_get(c->disk_sb.sb, downgrade);
	if (!d)
		return;

	struct bch_sb_field_ext *ext = bch2_sb_field_get(c->disk_sb.sb, ext);

	for_each_downgrade_entry(d, i) {
		unsigned minor = BCH_VERSION_MINOR(le16_to_cpu(i->version));
		if (new_minor < minor && minor <= old_minor) {
			ext->recovery_passes_required[0] |= i->recovery_passes[0];
			ext->recovery_passes_required[1] |= i->recovery_passes[1];

			for (unsigned j = 0; j < le16_to_cpu(i->nr_errors); j++) {
				unsigned e = le16_to_cpu(i->errors[j]);
				if (e < BCH_SB_ERR_MAX)
					__set_bit(e, c->sb.errors_silent);
				if (e < sizeof(ext->errors_silent) * 8)
					ext->errors_silent[e / 64] |= cpu_to_le64(BIT_ULL(e % 64));
			}
		}
	}
}