Current File : //usr/src/blksnap-6.3.0.73/snapimage.h
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __BLK_SNAP_SNAPIMAGE_H
#define __BLK_SNAP_SNAPIMAGE_H
#include <linux/blk_types.h>
#ifdef HAVE_GENHD_H
#include <linux/genhd.h>
#endif
#include <linux/blkdev.h>
#include <linux/blk-mq.h>
#include <linux/kthread.h>
struct diff_area;
struct cbt_map;
/**
* struct snapimage - Snapshot image block device.
*
* @image_dev_id:
* ID of the snapshot image block device.
* @capacity:
* The size of the snapshot image in sectors must be equal to the size
* of the original device at the time of taking the snapshot.
* @worker:
* The worker thread for processing I/O requests.
* @worker_task:
* A pointer to the &struct task of the worker thread.
* @tag_set:
* Area to keep a shared tag map.
* @disk:
* A pointer to the &struct gendisk for the image block device.
* @diff_area:
* A pointer to the owned &struct diff_area.
* @cbt_map:
* A pointer to the owned &struct cbt_map.
*
* The snapshot image is presented in the system as a block device. But
* when reading or writing a snapshot image, the data is redirected to
* the original block device or to the block device of the difference storage.
*
* The module does not prohibit reading and writing data to the snapshot
* from different threads in parallel. To avoid the problem with simultaneous
* access, it is enough to open the snapshot image block device with the
* FMODE_EXCL parameter.
*/
struct snapimage {
dev_t image_dev_id;
sector_t capacity;
struct kthread_worker worker;
struct task_struct *worker_task;
struct blk_mq_tag_set tag_set;
struct gendisk *disk;
#ifndef HAVE_BLK_MQ_ALLOC_DISK
struct request_queue *queue;
#endif
struct diff_area *diff_area;
struct cbt_map *cbt_map;
};
int snapimage_init(void);
void snapimage_done(void);
int snapimage_major(void);
void snapimage_free(struct snapimage *snapimage);
struct snapimage *snapimage_create(struct diff_area *diff_area,
struct cbt_map *cbt_map);
#ifdef BLK_SNAP_DEBUG_SECTOR_STATE
int snapimage_get_chunk_state(struct snapimage *snapimage, sector_t sector,
struct blk_snap_sector_state *state);
#endif
#endif /* __BLK_SNAP_SNAPIMAGE_H */
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