drivers/md/dm-clone-metadata.h

Source file repositories/reference/linux-study-clean/drivers/md/dm-clone-metadata.h

File Facts

System
Linux kernel
Corpus path
drivers/md/dm-clone-metadata.h
Extension
.h
Size
5773 bytes
Lines
178
Domain
Driver Families
Bucket
drivers/md
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef DM_CLONE_METADATA_H
#define DM_CLONE_METADATA_H

#include "persistent-data/dm-block-manager.h"
#include "persistent-data/dm-space-map-metadata.h"

#define DM_CLONE_METADATA_BLOCK_SIZE DM_SM_METADATA_BLOCK_SIZE

/*
 * The metadata device is currently limited in size.
 */
#define DM_CLONE_METADATA_MAX_SECTORS DM_SM_METADATA_MAX_SECTORS

/*
 * A metadata device larger than 16GB triggers a warning.
 */
#define DM_CLONE_METADATA_MAX_SECTORS_WARNING (16 * (1024 * 1024 * 1024 >> SECTOR_SHIFT))

#define SPACE_MAP_ROOT_SIZE 128

/* dm-clone metadata */
struct dm_clone_metadata;

/*
 * Set region status to hydrated.
 *
 * @cmd: The dm-clone metadata
 * @region_nr: The region number
 *
 * This function doesn't block, so it's safe to call it from interrupt context.
 */
int dm_clone_set_region_hydrated(struct dm_clone_metadata *cmd, unsigned long region_nr);

/*
 * Set status of all regions in the provided range to hydrated, if not already
 * hydrated.
 *
 * @cmd: The dm-clone metadata
 * @start: Starting region number
 * @nr_regions: Number of regions in the range
 *
 * This function doesn't block, but since it uses spin_lock_irq()/spin_unlock_irq()
 * it's NOT safe to call it from any context where interrupts are disabled, e.g.,
 * from interrupt context.
 */
int dm_clone_cond_set_range(struct dm_clone_metadata *cmd, unsigned long start,
			    unsigned long nr_regions);

/*
 * Read existing or create fresh metadata.
 *
 * @bdev: The device storing the metadata
 * @target_size: The target size
 * @region_size: The region size
 *
 * @returns: The dm-clone metadata
 *
 * This function reads the superblock of @bdev and checks if it's all zeroes.
 * If it is, it formats @bdev and creates fresh metadata. If it isn't, it
 * validates the metadata stored in @bdev.
 */
struct dm_clone_metadata *dm_clone_metadata_open(struct block_device *bdev,
						 sector_t target_size,
						 sector_t region_size);

/*
 * Free the resources related to metadata management.
 */
void dm_clone_metadata_close(struct dm_clone_metadata *cmd);

/*
 * Commit dm-clone metadata to disk.
 *
 * We use a two phase commit:
 *
 * 1. dm_clone_metadata_pre_commit(): Prepare the current transaction for
 *    committing. After this is called, all subsequent metadata updates, done
 *    through either dm_clone_set_region_hydrated() or
 *    dm_clone_cond_set_range(), will be part of the **next** transaction.
 *
 * 2. dm_clone_metadata_commit(): Actually commit the current transaction to
 *    disk and start a new transaction.
 *
 * This allows dm-clone to flush the destination device after step (1) to
 * ensure that all freshly hydrated regions, for which we are updating the
 * metadata, are properly written to non-volatile storage and won't be lost in
 * case of a crash.
 */
int dm_clone_metadata_pre_commit(struct dm_clone_metadata *cmd);
int dm_clone_metadata_commit(struct dm_clone_metadata *cmd);

Annotation

Implementation Notes