bcachefs-tools/libbcachefs/buckets_types.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _BUCKETS_TYPES_H
#define _BUCKETS_TYPES_H

#include "bcachefs_format.h"
#include "util.h"

#define BUCKET_JOURNAL_SEQ_BITS		16

/*
 * Ugly hack alert:
 *
 * We need to cram a spinlock in a single byte, because that's what we have left
 * in struct bucket, and we care about the size of these - during fsck, we need
 * in memory state for every single bucket on every device.
 *
 * We used to do
 *   while (xchg(&b->lock, 1) cpu_relax();
 * but, it turns out not all architectures support xchg on a single byte.
 *
 * So now we use bit_spin_lock(), with fun games since we can't burn a whole
 * ulong for this - we just need to make sure the lock bit always ends up in the
 * first byte.
 */

#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
#define BUCKET_LOCK_BITNR	0
#else
#define BUCKET_LOCK_BITNR	(BITS_PER_LONG - 1)
#endif

union ulong_byte_assert {
	ulong	ulong;
	u8	byte;
};

struct bucket {
	u8			lock;
	u8			gen_valid:1;
	u8			data_type:7;
	u8			gen;
	u8			stripe_redundancy;
	u32			stripe;
	u32			dirty_sectors;
	u32			cached_sectors;
	u32			stripe_sectors;
} __aligned(sizeof(long));

struct bucket_gens {
	struct rcu_head		rcu;
	u16			first_bucket;
	size_t			nbuckets;
	size_t			nbuckets_minus_first;
	u8			b[] __counted_by(nbuckets);
};

struct bch_dev_usage {
	struct bch_dev_usage_type {
		u64		buckets;
		u64		sectors; /* _compressed_ sectors: */
		/*
		 * XXX
		 * Why do we have this? Isn't it just buckets * bucket_size -
		 * sectors?
		 */
		u64		fragmented;
	}			d[BCH_DATA_NR];
};

struct bch_fs_usage_base {
	u64			hidden;
	u64			btree;
	u64			data;
	u64			cached;
	u64			reserved;
	u64			nr_inodes;
};

struct bch_fs_usage_short {
	u64			capacity;
	u64			used;
	u64			free;
	u64			nr_inodes;
};

/*
 * A reservation for space on disk:
 */
struct disk_reservation {
	u64			sectors;
	u32			gen;
	unsigned		nr_replicas;
};

#endif /* _BUCKETS_TYPES_H */