drivers/nvdimm/btt.h

/*
 * Block Translation Table library
 * Copyright (c) 2014-2015, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 */

#ifndef _LINUX_BTT_H
#define _LINUX_BTT_H

#include <linux/types.h>

#define BTT_SIG_LEN 16
#define BTT_SIG "BTT_ARENA_INFO\0"
#define MAP_ENT_SIZE 4
#define MAP_TRIM_SHIFT 31
#define MAP_TRIM_MASK (1 << MAP_TRIM_SHIFT)
#define MAP_ERR_SHIFT 30
#define MAP_ERR_MASK (1 << MAP_ERR_SHIFT)
#define MAP_LBA_MASK (~((1 << MAP_TRIM_SHIFT) | (1 << MAP_ERR_SHIFT)))
#define MAP_ENT_NORMAL 0xC0000000
#define LOG_GRP_SIZE sizeof(struct log_group)
#define LOG_ENT_SIZE sizeof(struct log_entry)
#define ARENA_MIN_SIZE (1UL << 24)	/* 16 MB */
#define ARENA_MAX_SIZE (1ULL << 39)	/* 512 GB */
#define RTT_VALID (1UL << 31)
#define RTT_INVALID 0
#define BTT_PG_SIZE 4096
#define BTT_DEFAULT_NFREE ND_MAX_LANES
#define LOG_SEQ_INIT 1

#define IB_FLAG_ERROR 0x00000001
#define IB_FLAG_ERROR_MASK 0x00000001

enum btt_init_state {
	INIT_UNCHECKED = 0,
	INIT_NOTFOUND,
	INIT_READY
};

/*
 * A log group represents one log 'lane', and consists of four log entries.
 * Two of the four entries are valid entries, and the remaining two are
 * padding. Due to an old bug in the padding location, we need to perform a
 * test to determine the padding scheme being used, and use that scheme
 * thereafter.
 *
 * In kernels prior to 4.15, 'log group' would have actual log entries at
 * indices (0, 2) and padding at indices (1, 3), where as the correct/updated
 * format has log entries at indices (0, 1) and padding at indices (2, 3).
 *
 * Old (pre 4.15) format:
 * +-----------------+-----------------+
 * |      ent[0]     |      ent[1]     |
 * |       16B       |       16B       |
 * | lba/old/new/seq |       pad       |
 * +-----------------------------------+
 * |      ent[2]     |      ent[3]     |
 * |       16B       |       16B       |
 * | lba/old/new/seq |       pad       |
 * +-----------------+-----------------+
 *
 * New format:
 * +-----------------+-----------------+
 * |      ent[0]     |      ent[1]     |
 * |       16B       |       16B       |
 * | lba/old/new/seq | lba/old/new/seq |
 * +-----------------------------------+
 * |      ent[2]     |      ent[3]     |
 * |       16B       |       16B       |
 * |       pad       |       pad       |
 * +-----------------+-----------------+
 *
 * We detect during start-up which format is in use, and set
 * arena->log_index[(0, 1)] with the detected format.
 */

struct log_entry {
	__le32 lba;
	__le32 old_map;
	__le32 new_map;
	__le32 seq;
};

struct log_group {
	struct log_entry ent[4];
};

struct btt_sb {
	u8 signature[BTT_SIG_LEN];
	u8 uuid[16];
	u8 parent_uuid[16];
	__le32 flags;
	__le16 version_major;
	__le16 version_minor;
	__le32 external_lbasize;
	__le32 external_nlba;
	__le32 internal_lbasize;
	__le32 internal_nlba;
	__le32 nfree;
	__le32 infosize;
	__le64 nextoff;
	__le64 dataoff;
	__le64 mapoff;
	__le64 logoff;
	__le64 info2off;
	u8 padding[3968];
	__le64 checksum;
};

struct free_entry {
	u32 block;
	u8 sub;
	u8 seq;
};

struct aligned_lock {
	union {
		spinlock_t lock;
		u8 cacheline_padding[L1_CACHE_BYTES];
	};
};

/**
 * struct arena_info - handle for an arena
 * @size:		Size in bytes this arena occupies on the raw device.
 *			This includes arena metadata.
 * @external_lba_start:	The first external LBA in this arena.
 * @internal_nlba:	Number of internal blocks available in the arena
 *			including nfree reserved blocks
 * @internal_lbasize:	Internal and external lba sizes may be different as
 *			we can round up 'odd' external lbasizes such as 520B
 *			to be aligned.
 * @external_nlba:	Number of blocks contributed by the arena to the number
 *			reported to upper layers. (internal_nlba - nfree)
 * @external_lbasize:	LBA size as exposed to upper layers.
 * @nfree:		A reserve number of 'free' blocks that is used to
 *			handle incoming writes.
 * @version_major:	Metadata layout version major.
 * @version_minor:	Metadata layout version minor.
 * @nextoff:		Offset in bytes to the start of the next arena.
 * @infooff:		Offset in bytes to the info block of this arena.
 * @dataoff:		Offset in bytes to the data area of this arena.
 * @mapoff:		Offset in bytes to the map area of this arena.
 * @logoff:		Offset in bytes to the log area of this arena.
 * @info2off:		Offset in bytes to the backup info block of this arena.
 * @freelist:		Pointer to in-memory list of free blocks
 * @rtt:		Pointer to in-memory "Read Tracking Table"
 * @map_locks:		Spinlocks protecting concurrent map writes
 * @nd_btt:		Pointer to parent nd_btt structure.
 * @list:		List head for list of arenas
 * @debugfs_dir:	Debugfs dentry
 * @flags:		Arena flags - may signify error states.
 * @log_index:		Indices of the valid log entries in a log_group
 *
 * arena_info is a per-arena handle. Once an arena is narrowed down for an
 * IO, this struct is passed around for the duration of the IO.
 */
struct arena_info {
	u64 size;			/* Total bytes for this arena */
	u64 external_lba_start;
	u32 internal_nlba;
	u32 internal_lbasize;
	u32 external_nlba;
	u32 external_lbasize;
	u32 nfree;
	u16 version_major;
	u16 version_minor;
	/* Byte offsets to the different on-media structures */
	u64 nextoff;
	u64 infooff;
	u64 dataoff;
	u64 mapoff;
	u64 logoff;
	u64 info2off;
	/* Pointers to other in-memory structures for this arena */
	struct free_entry *freelist;
	u32 *rtt;
	struct aligned_lock *map_locks;
	struct nd_btt *nd_btt;
	struct list_head list;
	struct dentry *debugfs_dir;
	/* Arena flags */
	u32 flags;
	int log_index[2];
};

/**
 * struct btt - handle for a BTT instance
 * @btt_disk:		Pointer to the gendisk for BTT device
 * @btt_queue:		Pointer to the request queue for the BTT device
 * @arena_list:		Head of the list of arenas
 * @debugfs_dir:	Debugfs dentry
 * @nd_btt:		Parent nd_btt struct
 * @nlba:		Number of logical blocks exposed to the	upper layers
 *			after removing the amount of space needed by metadata
 * @rawsize:		Total size in bytes of the available backing device
 * @lbasize:		LBA size as requested and presented to upper layers.
 *			This is sector_size + size of any metadata.
 * @sector_size:	The Linux sector size - 512 or 4096
 * @lanes:		Per-lane spinlocks
 * @init_lock:		Mutex used for the BTT initialization
 * @init_state:		Flag describing the initialization state for the BTT
 * @num_arenas:		Number of arenas in the BTT instance
 */
struct btt {
	struct gendisk *btt_disk;
	struct request_queue *btt_queue;
	struct list_head arena_list;
	struct dentry *debugfs_dir;
	struct nd_btt *nd_btt;
	u64 nlba;
	unsigned long long rawsize;
	u32 lbasize;
	u32 sector_size;
	struct nd_region *nd_region;
	struct mutex init_lock;
	int init_state;
	int num_arenas;
};

bool nd_btt_arena_is_valid(struct nd_btt *nd_btt, struct btt_sb *super);

#endif