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linux/drivers/md/dm-vdo/indexer/indexer.h

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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright 2023 Red Hat
*/
#ifndef INDEXER_H
#define INDEXER_H
#include <linux/mutex.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/wait.h>
#include "funnel-queue.h"
/*
* UDS public API
*
* The Universal Deduplication System (UDS) is an efficient name-value store. When used for
* deduplicating storage, the names are generally hashes of data blocks and the associated data is
* where that block is located on the underlying storage medium. The stored names are expected to
* be randomly distributed among the space of possible names. If this assumption is violated, the
* UDS index will store fewer names than normal but will otherwise continue to work. The data
* associated with each name can be any 16-byte value.
*
* A client must first create an index session to interact with an index. Once created, the session
* can be shared among multiple threads or users. When a session is destroyed, it will also close
* and save any associated index.
*
* To make a request, a client must allocate a uds_request structure and set the required fields
* before launching it. UDS will invoke the provided callback to complete the request. After the
* callback has been called, the uds_request structure can be freed or reused for a new request.
* There are five types of requests:
*
* A UDS_UPDATE request will associate the provided name with the provided data. Any previous data
* associated with that name will be discarded.
*
* A UDS_QUERY request will return the data associated with the provided name, if any. The entry
* for the name will also be marked as most recent, as if the data had been updated.
*
* A UDS_POST request is a combination of UDS_QUERY and UDS_UPDATE. If there is already data
* associated with the provided name, that data is returned. If there is no existing association,
* the name is associated with the newly provided data. This request is equivalent to a UDS_QUERY
* request followed by a UDS_UPDATE request if no data is found, but it is much more efficient.
*
* A UDS_QUERY_NO_UPDATE request will return the data associated with the provided name, but will
* not change the recency of the entry for the name. This request is primarily useful for testing,
* to determine whether an entry exists without changing the internal state of the index.
*
* A UDS_DELETE request removes any data associated with the provided name. This operation is
* generally not necessary, because the index will automatically discard its oldest entries once it
* becomes full.
*/
/* General UDS constants and structures */
enum uds_request_type {
/* Create or update the mapping for a name, and make the name most recent. */
UDS_UPDATE,
/* Return any mapped data for a name, and make the name most recent. */
UDS_QUERY,
/*
* Return any mapped data for a name, or map the provided data to the name if there is no
* current data, and make the name most recent.
*/
UDS_POST,
/* Return any mapped data for a name without updating its recency. */
UDS_QUERY_NO_UPDATE,
/* Remove any mapping for a name. */
UDS_DELETE,
};
enum uds_open_index_type {
/* Create a new index. */
UDS_CREATE,
/* Load an existing index and try to recover if necessary. */
UDS_LOAD,
/* Load an existing index, but only if it was saved cleanly. */
UDS_NO_REBUILD,
};
enum {
/* The record name size in bytes */
UDS_RECORD_NAME_SIZE = 16,
/* The maximum record data size in bytes */
UDS_RECORD_DATA_SIZE = 16,
};
/*
* A type representing a UDS memory configuration which is either a positive integer number of
* gigabytes or one of the six special constants for configurations smaller than one gigabyte.
*/
typedef int uds_memory_config_size_t;
enum {
/* The maximum configurable amount of memory */
UDS_MEMORY_CONFIG_MAX = 1024,
/* Flag indicating that the index has one less chapter than usual */
UDS_MEMORY_CONFIG_REDUCED = 0x1000,
UDS_MEMORY_CONFIG_REDUCED_MAX = 1024 + UDS_MEMORY_CONFIG_REDUCED,
/* Special values indicating sizes less than 1 GB */
UDS_MEMORY_CONFIG_256MB = -256,
UDS_MEMORY_CONFIG_512MB = -512,
UDS_MEMORY_CONFIG_768MB = -768,
UDS_MEMORY_CONFIG_REDUCED_256MB = -1280,
UDS_MEMORY_CONFIG_REDUCED_512MB = -1536,
UDS_MEMORY_CONFIG_REDUCED_768MB = -1792,
};
struct uds_record_name {
unsigned char name[UDS_RECORD_NAME_SIZE];
};
struct uds_record_data {
unsigned char data[UDS_RECORD_DATA_SIZE];
};
struct uds_volume_record {
struct uds_record_name name;
struct uds_record_data data;
};
struct uds_parameters {
/* The block_device used for storage */
struct block_device *bdev;
/* The maximum allowable size of the index on storage */
size_t size;
/* The offset where the index should start */
off_t offset;
/* The maximum memory allocation, in GB */
uds_memory_config_size_t memory_size;
/* Whether the index should include sparse chapters */
bool sparse;
/* A 64-bit nonce to validate the index */
u64 nonce;
/* The number of threads used to process index requests */
unsigned int zone_count;
/* The number of threads used to read volume pages */
unsigned int read_threads;
};
/*
* These statistics capture characteristics of the current index, including resource usage and
* requests processed since the index was opened.
*/
struct uds_index_stats {
/* The total number of records stored in the index */
u64 entries_indexed;
/* An estimate of the index's memory usage, in bytes */
u64 memory_used;
/* The number of collisions recorded in the volume index */
u64 collisions;
/* The number of entries discarded from the index since startup */
u64 entries_discarded;
/* The time at which these statistics were fetched */
s64 current_time;
/* The number of post calls that found an existing entry */
u64 posts_found;
/* The number of post calls that added an entry */
u64 posts_not_found;
/*
* The number of post calls that found an existing entry that is current enough to only
* exist in memory and not have been committed to disk yet
*/
u64 in_memory_posts_found;
/*
* The number of post calls that found an existing entry in the dense portion of the index
*/
u64 dense_posts_found;
/*
* The number of post calls that found an existing entry in the sparse portion of the index
*/
u64 sparse_posts_found;
/* The number of update calls that updated an existing entry */
u64 updates_found;
/* The number of update calls that added a new entry */
u64 updates_not_found;
/* The number of delete requests that deleted an existing entry */
u64 deletions_found;
/* The number of delete requests that did nothing */
u64 deletions_not_found;
/* The number of query calls that found existing entry */
u64 queries_found;
/* The number of query calls that did not find an entry */
u64 queries_not_found;
/* The total number of requests processed */
u64 requests;
};
enum uds_index_region {
/* No location information has been determined */
UDS_LOCATION_UNKNOWN = 0,
/* The index page entry has been found */
UDS_LOCATION_INDEX_PAGE_LOOKUP,
/* The record page entry has been found */
UDS_LOCATION_RECORD_PAGE_LOOKUP,
/* The record is not in the index */
UDS_LOCATION_UNAVAILABLE,
/* The record was found in the open chapter */
UDS_LOCATION_IN_OPEN_CHAPTER,
/* The record was found in the dense part of the index */
UDS_LOCATION_IN_DENSE,
/* The record was found in the sparse part of the index */
UDS_LOCATION_IN_SPARSE,
} __packed;
/* Zone message requests are used to communicate between index zones. */
enum uds_zone_message_type {
/* A standard request with no message */
UDS_MESSAGE_NONE = 0,
/* Add a chapter to the sparse chapter index cache */
UDS_MESSAGE_SPARSE_CACHE_BARRIER,
/* Close a chapter to keep the zone from falling behind */
UDS_MESSAGE_ANNOUNCE_CHAPTER_CLOSED,
} __packed;
struct uds_zone_message {
/* The type of message, determining how it will be processed */
enum uds_zone_message_type type;
/* The virtual chapter number to which the message applies */
u64 virtual_chapter;
};
struct uds_index_session;
struct uds_index;
struct uds_request;
/* Once this callback has been invoked, the uds_request structure can be reused or freed. */
typedef void (*uds_request_callback_fn)(struct uds_request *request);
struct uds_request {
/* These input fields must be set before launching a request. */
/* The name of the record to look up or create */
struct uds_record_name record_name;
/* New data to associate with the record name, if applicable */
struct uds_record_data new_metadata;
/* A callback to invoke when the request is complete */
uds_request_callback_fn callback;
/* The index session that will manage this request */
struct uds_index_session *session;
/* The type of operation to perform, as describe above */
enum uds_request_type type;
/* These output fields are set when a request is complete. */
/* The existing data associated with the request name, if any */
struct uds_record_data old_metadata;
/* Either UDS_SUCCESS or an error code for the request */
int status;
/* True if the record name had an existing entry in the index */
bool found;
/*
* The remaining fields are used internally and should not be altered by clients. The index
* relies on zone_number being the first field in this section.
*/
/* The number of the zone which will process this request*/
unsigned int zone_number;
/* A link for adding a request to a lock-free queue */
struct funnel_queue_entry queue_link;
/* A link for adding a request to a standard linked list */
struct uds_request *next_request;
/* A pointer to the index processing this request */
struct uds_index *index;
/* Control message for coordinating between zones */
struct uds_zone_message zone_message;
/* If true, process request immediately by waking the worker thread */
bool unbatched;
/* If true, continue this request before processing newer requests */
bool requeued;
/* The virtual chapter containing the record name, if known */
u64 virtual_chapter;
/* The region of the index containing the record name */
enum uds_index_region location;
};
/* Compute the number of bytes needed to store an index. */
int __must_check uds_compute_index_size(const struct uds_parameters *parameters,
u64 *index_size);
/* A session is required for most index operations. */
int __must_check uds_create_index_session(struct uds_index_session **session);
/* Destroying an index session also closes and saves the associated index. */
int uds_destroy_index_session(struct uds_index_session *session);
/*
* Create or open an index with an existing session. This operation fails if the index session is
* suspended, or if there is already an open index.
*/
int __must_check uds_open_index(enum uds_open_index_type open_type,
const struct uds_parameters *parameters,
struct uds_index_session *session);
/*
* Wait until all callbacks for index operations are complete, and prevent new index operations
* from starting. New index operations will fail with EBUSY until the session is resumed. Also
* optionally saves the index.
*/
int __must_check uds_suspend_index_session(struct uds_index_session *session, bool save);
/*
* Allow new index operations for an index, whether it was suspended or not. If the index is
* suspended and the supplied block device differs from the current backing store, the index will
* start using the new backing store instead.
*/
int __must_check uds_resume_index_session(struct uds_index_session *session,
struct block_device *bdev);
/* Wait until all outstanding index operations are complete. */
int __must_check uds_flush_index_session(struct uds_index_session *session);
/* Close an index. This operation fails if the index session is suspended. */
int __must_check uds_close_index(struct uds_index_session *session);
/* Get index statistics since the last time the index was opened. */
int __must_check uds_get_index_session_stats(struct uds_index_session *session,
struct uds_index_stats *stats);
/* This function will fail if any required field of the request is not set. */
int __must_check uds_launch_request(struct uds_request *request);
struct cond_var {
wait_queue_head_t wait_queue;
};
static inline void uds_init_cond(struct cond_var *cv)
{
init_waitqueue_head(&cv->wait_queue);
}
static inline void uds_signal_cond(struct cond_var *cv)
{
wake_up(&cv->wait_queue);
}
static inline void uds_broadcast_cond(struct cond_var *cv)
{
wake_up_all(&cv->wait_queue);
}
void uds_wait_cond(struct cond_var *cv, struct mutex *mutex);
#endif /* INDEXER_H */