/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright 2023 Red Hat
*/
#ifndef VDO_RECOVERY_JOURNAL_H
#define VDO_RECOVERY_JOURNAL_H
#include <linux/list.h>
#include "numeric.h"
#include "admin-state.h"
#include "constants.h"
#include "encodings.h"
#include "flush.h"
#include "statistics.h"
#include "types.h"
#include "wait-queue.h"
/**
* DOC: recovery journal.
*
* The recovery_journal provides a log of all block mapping and reference count changes which have
* not yet been stably written to the block map or slab journals. This log helps to reduce the
* write amplification of writes by providing amortization of slab journal and block map page
* updates.
*
* The recovery journal has a single dedicated queue and thread for performing all journal updates.
* The concurrency guarantees of this single-threaded model allow the code to omit more
* fine-grained locking for recovery journal structures.
*
* The journal consists of a set of on-disk blocks arranged as a circular log with monotonically
* increasing sequence numbers. Three sequence numbers serve to define the active extent of the
* journal. The 'head' is the oldest active block in the journal. The 'tail' is the end of the
* half-open interval containing the active blocks. 'active' is the number of the block actively
* receiving entries. In an empty journal, head == active == tail. Once any entries are added, tail
* = active + 1, and head may be any value in the interval [tail - size, active].
*
* The journal also contains a set of in-memory blocks which are used to buffer up entries until
* they can be committed. In general the number of in-memory blocks ('tail_buffer_count') will be
* less than the on-disk size. Each in-memory block is also a vdo_completion. Each in-memory block
* has a vio which is used to commit that block to disk. The vio's data is the on-disk
* representation of the journal block. In addition each in-memory block has a buffer which is used
* to accumulate entries while a partial commit of the block is in progress. In-memory blocks are
* kept on two rings. Free blocks live on the 'free_tail_blocks' ring. When a block becomes active
* (see below) it is moved to the 'active_tail_blocks' ring. When a block is fully committed, it is
* moved back to the 'free_tail_blocks' ring.
*
* When entries are added to the journal, they are added to the active in-memory block, as
* indicated by the 'active_block' field. If the caller wishes to wait for the entry to be
* committed, the requesting VIO will be attached to the in-memory block to which the caller's
* entry was added. If the caller does wish to wait, or if the entry filled the active block, an
* attempt will be made to commit that block to disk. If there is already another commit in
* progress, the attempt will be ignored and then automatically retried when the in-progress commit
* completes. If there is no commit in progress, any data_vios waiting on the block are transferred
* to the block's vio which is then written, automatically waking all of the waiters when it
* completes. When the write completes, any entries which accumulated in the block are copied to
* the vio's data buffer.
*
* Finally, the journal maintains a set of counters, one for each on disk journal block. These
* counters are used as locks to prevent premature reaping of journal blocks. Each time a new
* sequence number is used, the counter for the corresponding block is incremented. The counter is
* subsequently decremented when that block is filled and then committed for the last time. This
* prevents blocks from being reaped while they are still being updated. The counter is also
* incremented once for each entry added to a block, and decremented once each time the block map
* is updated in memory for that request. This prevents blocks from being reaped while their VIOs
* are still active. Finally, each in-memory block map page tracks the oldest journal block that
* contains entries corresponding to uncommitted updates to that block map page. Each time an
* in-memory block map page is updated, it checks if the journal block for the VIO is earlier than
* the one it references, in which case it increments the count on the earlier journal block and
* decrements the count on the later journal block, maintaining a lock on the oldest journal block
* containing entries for that page. When a block map page has been flushed from the cache, the
* counter for the journal block it references is decremented. Whenever the counter for the head
* block goes to 0, the head is advanced until it comes to a block whose counter is not 0 or until
* it reaches the active block. This is the mechanism for reclaiming journal space on disk.
*
* If there is no in-memory space when a VIO attempts to add an entry, the VIO will be attached to
* the 'commit_completion' and will be woken the next time a full block has committed. If there is
* no on-disk space when a VIO attempts to add an entry, the VIO will be attached to the
* 'reap_completion', and will be woken the next time a journal block is reaped.
*/
enum vdo_zone_type {
VDO_ZONE_TYPE_ADMIN,
VDO_ZONE_TYPE_JOURNAL,
VDO_ZONE_TYPE_LOGICAL,
VDO_ZONE_TYPE_PHYSICAL,
};
struct lock_counter {
/* The completion for notifying the owner of a lock release */
struct vdo_completion completion;
/* The number of logical zones which may hold locks */
zone_count_t logical_zones;
/* The number of physical zones which may hold locks */
zone_count_t physical_zones;
/* The number of locks */
block_count_t locks;
/* Whether the lock release notification is in flight */
atomic_t state;
/* The number of logical zones which hold each lock */
atomic_t *logical_zone_counts;
/* The number of physical zones which hold each lock */
atomic_t *physical_zone_counts;
/* The per-lock counts for the journal zone */
u16 *journal_counters;
/* The per-lock decrement counts for the journal zone */
atomic_t *journal_decrement_counts;
/* The per-zone, per-lock reference counts for logical zones */
u16 *logical_counters;
/* The per-zone, per-lock reference counts for physical zones */
u16 *physical_counters;
};
struct recovery_journal_block {
/* The doubly linked pointers for the free or active lists */
struct list_head list_node;
/* The waiter for the pending full block list */
struct vdo_waiter write_waiter;
/* The journal to which this block belongs */
struct recovery_journal *journal;
/* A pointer to the current sector in the packed block buffer */
struct packed_journal_sector *sector;
/* The vio for writing this block */
struct vio vio;
/* The sequence number for this block */
sequence_number_t sequence_number;
/* The location of this block in the on-disk journal */
physical_block_number_t block_number;
/* Whether this block is being committed */
bool committing;
/* The total number of entries in this block */
journal_entry_count_t entry_count;
/* The total number of uncommitted entries (queued or committing) */
journal_entry_count_t uncommitted_entry_count;
/* The number of new entries in the current commit */
journal_entry_count_t entries_in_commit;
/* The queue of vios which will make entries for the next commit */
struct vdo_wait_queue entry_waiters;
/* The queue of vios waiting for the current commit */
struct vdo_wait_queue commit_waiters;
};
struct recovery_journal {
/* The thread ID of the journal zone */
thread_id_t thread_id;
/* The slab depot which can hold locks on this journal */
struct slab_depot *depot;
/* The block map which can hold locks on this journal */
struct block_map *block_map;
/* The queue of vios waiting to make entries */
struct vdo_wait_queue entry_waiters;
/* The number of free entries in the journal */
u64 available_space;
/* The number of decrement entries which need to be made */
data_vio_count_t pending_decrement_count;
/* Whether the journal is adding entries from the increment or decrement waiters queues */
bool adding_entries;
/* The administrative state of the journal */
struct admin_state state;
/* Whether a reap is in progress */
bool reaping;
/* The location of the first journal block */
physical_block_number_t origin;
/* The oldest active block in the journal on disk for block map rebuild */
sequence_number_t block_map_head;
/* The oldest active block in the journal on disk for slab journal replay */
sequence_number_t slab_journal_head;
/* The newest block in the journal on disk to which a write has finished */
sequence_number_t last_write_acknowledged;
/* The end of the half-open interval of the active journal */
sequence_number_t tail;
/* The point at which the last entry will have been added */
struct journal_point append_point;
/* The journal point of the vio most recently released from the journal */
struct journal_point commit_point;
/* The nonce of the VDO */
nonce_t nonce;
/* The number of recoveries completed by the VDO */
u8 recovery_count;
/* The number of entries which fit in a single block */
journal_entry_count_t entries_per_block;
/* Unused in-memory journal blocks */
struct list_head free_tail_blocks;
/* In-memory journal blocks with records */
struct list_head active_tail_blocks;
/* A pointer to the active block (the one we are adding entries to now) */
struct recovery_journal_block *active_block;
/* Journal blocks that need writing */
struct vdo_wait_queue pending_writes;
/* The new block map reap head after reaping */
sequence_number_t block_map_reap_head;
/* The head block number for the block map rebuild range */
block_count_t block_map_head_block_number;
/* The new slab journal reap head after reaping */
sequence_number_t slab_journal_reap_head;
/* The head block number for the slab journal replay range */
block_count_t slab_journal_head_block_number;
/* The data-less vio, usable only for flushing */
struct vio *flush_vio;
/* The number of blocks in the on-disk journal */
block_count_t size;
/* The number of logical blocks that are in-use */
block_count_t logical_blocks_used;
/* The number of block map pages that are allocated */
block_count_t block_map_data_blocks;
/* The number of journal blocks written but not yet acknowledged */
block_count_t pending_write_count;
/* The threshold at which slab journal tail blocks will be written out */
block_count_t slab_journal_commit_threshold;
/* Counters for events in the journal that are reported as statistics */
struct recovery_journal_statistics events;
/* The locks for each on-disk block */
struct lock_counter lock_counter;
/* The tail blocks */
struct recovery_journal_block blocks[];
};
/**
* vdo_get_recovery_journal_block_number() - Get the physical block number for a given sequence
* number.
* @journal: The journal.
* @sequence: The sequence number of the desired block.
*
* Return: The block number corresponding to the sequence number.
*/
static inline physical_block_number_t __must_check
vdo_get_recovery_journal_block_number(const struct recovery_journal *journal,
sequence_number_t sequence)
{
/*
* Since journal size is a power of two, the block number modulus can just be extracted
* from the low-order bits of the sequence.
*/
return vdo_compute_recovery_journal_block_number(journal->size, sequence);
}
/**
* vdo_compute_recovery_journal_check_byte() - Compute the check byte for a given sequence number.
* @journal: The journal.
* @sequence: The sequence number.
*
* Return: The check byte corresponding to the sequence number.
*/
static inline u8 __must_check
vdo_compute_recovery_journal_check_byte(const struct recovery_journal *journal,
sequence_number_t sequence)
{
/* The check byte must change with each trip around the journal. */
return (((sequence / journal->size) & 0x7F) | 0x80);
}
int __must_check vdo_decode_recovery_journal(struct recovery_journal_state_7_0 state,
nonce_t nonce, struct vdo *vdo,
struct partition *partition,
u64 recovery_count,
block_count_t journal_size,
struct recovery_journal **journal_ptr);
void vdo_free_recovery_journal(struct recovery_journal *journal);
void vdo_initialize_recovery_journal_post_repair(struct recovery_journal *journal,
u64 recovery_count,
sequence_number_t tail,
block_count_t logical_blocks_used,
block_count_t block_map_data_blocks);
block_count_t __must_check
vdo_get_journal_block_map_data_blocks_used(struct recovery_journal *journal);
thread_id_t __must_check vdo_get_recovery_journal_thread_id(struct recovery_journal *journal);
void vdo_open_recovery_journal(struct recovery_journal *journal,
struct slab_depot *depot, struct block_map *block_map);
sequence_number_t
vdo_get_recovery_journal_current_sequence_number(struct recovery_journal *journal);
block_count_t __must_check vdo_get_recovery_journal_length(block_count_t journal_size);
struct recovery_journal_state_7_0 __must_check
vdo_record_recovery_journal(const struct recovery_journal *journal);
void vdo_add_recovery_journal_entry(struct recovery_journal *journal,
struct data_vio *data_vio);
void vdo_acquire_recovery_journal_block_reference(struct recovery_journal *journal,
sequence_number_t sequence_number,
enum vdo_zone_type zone_type,
zone_count_t zone_id);
void vdo_release_recovery_journal_block_reference(struct recovery_journal *journal,
sequence_number_t sequence_number,
enum vdo_zone_type zone_type,
zone_count_t zone_id);
void vdo_release_journal_entry_lock(struct recovery_journal *journal,
sequence_number_t sequence_number);
void vdo_drain_recovery_journal(struct recovery_journal *journal,
const struct admin_state_code *operation,
struct vdo_completion *parent);
void vdo_resume_recovery_journal(struct recovery_journal *journal,
struct vdo_completion *parent);
block_count_t __must_check
vdo_get_recovery_journal_logical_blocks_used(const struct recovery_journal *journal);
struct recovery_journal_statistics __must_check
vdo_get_recovery_journal_statistics(const struct recovery_journal *journal);
void vdo_dump_recovery_journal_statistics(const struct recovery_journal *journal);
#endif /* VDO_RECOVERY_JOURNAL_H */
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