/*
   * Copyright (C) 2010-2011 Red Hat, Inc.
   *
   * This file is released under the GPL.
   */
  
  #ifndef DM_THIN_METADATA_H
  #define DM_THIN_METADATA_H
  
  #include "persistent-data/dm-block-manager.h"
  #include "persistent-data/dm-space-map.h"
  #include "persistent-data/dm-space-map-metadata.h"
  
  #define THIN_METADATA_BLOCK_SIZE DM_SM_METADATA_BLOCK_SIZE
  
  /*
   * The metadata device is currently limited in size.
   */
  #define THIN_METADATA_MAX_SECTORS DM_SM_METADATA_MAX_SECTORS
  
  /*
   * A metadata device larger than 16GB triggers a warning.
   */
  #define THIN_METADATA_MAX_SECTORS_WARNING (16 * (1024 * 1024 * 1024 >> SECTOR_SHIFT))
  
  /*----------------------------------------------------------------*/
  
  /*
   * Thin metadata superblock flags.
   */
  #define THIN_METADATA_NEEDS_CHECK_FLAG (1 << 0)
  
  struct dm_pool_metadata;
  struct dm_thin_device;
  
  /*
   * Device identifier
   */
  typedef uint64_t dm_thin_id;
  
  /*
   * Reopens or creates a new, empty metadata volume.
   */
  struct dm_pool_metadata *dm_pool_metadata_open(struct block_device *bdev,
  					       sector_t data_block_size,
  					       bool format_device);
  
  int dm_pool_metadata_close(struct dm_pool_metadata *pmd);
  
  /*
   * Compat feature flags.  Any incompat flags beyond the ones
   * specified below will prevent use of the thin metadata.
   */
  #define THIN_FEATURE_COMPAT_SUPP	  0UL
  #define THIN_FEATURE_COMPAT_RO_SUPP	  0UL
  #define THIN_FEATURE_INCOMPAT_SUPP	  0UL
  
  /*
   * Device creation/deletion.
   */
  int dm_pool_create_thin(struct dm_pool_metadata *pmd, dm_thin_id dev);
  
  /*
   * An internal snapshot.
   *
   * You can only snapshot a quiesced origin i.e. one that is either
   * suspended or not instanced at all.
   */
  int dm_pool_create_snap(struct dm_pool_metadata *pmd, dm_thin_id dev,
  			dm_thin_id origin);
  
  /*
   * Deletes a virtual device from the metadata.  It _is_ safe to call this
   * when that device is open.  Operations on that device will just start
   * failing.  You still need to call close() on the device.
   */
  int dm_pool_delete_thin_device(struct dm_pool_metadata *pmd,
  			       dm_thin_id dev);
  
  /*
   * Commits _all_ metadata changes: device creation, deletion, mapping
   * updates.
   */
  int dm_pool_commit_metadata(struct dm_pool_metadata *pmd);
  
  /*
   * Discards all uncommitted changes.  Rereads the superblock, rolling back
   * to the last good transaction.  Thin devices remain open.
   * dm_thin_aborted_changes() tells you if they had uncommitted changes.
   *
   * If this call fails it's only useful to call dm_pool_metadata_close().
   * All other methods will fail with -EINVAL.
   */
  int dm_pool_abort_metadata(struct dm_pool_metadata *pmd);
  
  /*
   * Set/get userspace transaction id.
   */
  int dm_pool_set_metadata_transaction_id(struct dm_pool_metadata *pmd,
  					uint64_t current_id,
  					uint64_t new_id);
  
  int dm_pool_get_metadata_transaction_id(struct dm_pool_metadata *pmd,
  					uint64_t *result);
  
  /*
   * Hold/get root for userspace transaction.
   *
   * The metadata snapshot is a copy of the current superblock (minus the
   * space maps).  Userland can access the data structures for READ
   * operations only.  A small performance hit is incurred by providing this
   * copy of the metadata to userland due to extra copy-on-write operations
   * on the metadata nodes.  Release this as soon as you finish with it.
   */
  int dm_pool_reserve_metadata_snap(struct dm_pool_metadata *pmd);
  int dm_pool_release_metadata_snap(struct dm_pool_metadata *pmd);
  
  int dm_pool_get_metadata_snap(struct dm_pool_metadata *pmd,
  			      dm_block_t *result);
  
  /*
   * Actions on a single virtual device.
   */
  
  /*
   * Opening the same device more than once will fail with -EBUSY.
   */
  int dm_pool_open_thin_device(struct dm_pool_metadata *pmd, dm_thin_id dev,
  			     struct dm_thin_device **td);
  
  int dm_pool_close_thin_device(struct dm_thin_device *td);
  
  dm_thin_id dm_thin_dev_id(struct dm_thin_device *td);
  
  struct dm_thin_lookup_result {
  	dm_block_t block;
  	bool shared:1;
  };
  
  /*
   * Returns:
   *   -EWOULDBLOCK iff @can_block is set and would block.
   *   -ENODATA iff that mapping is not present.
   *   0 success
   */
  int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
  		       int can_block, struct dm_thin_lookup_result *result);
  
  /*
   * Obtain an unused block.
   */
  int dm_pool_alloc_data_block(struct dm_pool_metadata *pmd, dm_block_t *result);
  
  /*
   * Insert or remove block.
   */
  int dm_thin_insert_block(struct dm_thin_device *td, dm_block_t block,
  			 dm_block_t data_block);
  
  int dm_thin_remove_block(struct dm_thin_device *td, dm_block_t block);
  
  /*
   * Queries.
   */
  bool dm_thin_changed_this_transaction(struct dm_thin_device *td);
  
  bool dm_pool_changed_this_transaction(struct dm_pool_metadata *pmd);
  
  bool dm_thin_aborted_changes(struct dm_thin_device *td);
  
  int dm_thin_get_highest_mapped_block(struct dm_thin_device *td,
  				     dm_block_t *highest_mapped);
  
  int dm_thin_get_mapped_count(struct dm_thin_device *td, dm_block_t *result);
  
  int dm_pool_get_free_block_count(struct dm_pool_metadata *pmd,
  				 dm_block_t *result);
  
  int dm_pool_get_free_metadata_block_count(struct dm_pool_metadata *pmd,
  					  dm_block_t *result);
  
  int dm_pool_get_metadata_dev_size(struct dm_pool_metadata *pmd,
  				  dm_block_t *result);
  
  int dm_pool_get_data_block_size(struct dm_pool_metadata *pmd, sector_t *result);
  
  int dm_pool_get_data_dev_size(struct dm_pool_metadata *pmd, dm_block_t *result);
  
  int dm_pool_block_is_used(struct dm_pool_metadata *pmd, dm_block_t b, bool *result);
  
  /*
   * Returns -ENOSPC if the new size is too small and already allocated
   * blocks would be lost.
   */
  int dm_pool_resize_data_dev(struct dm_pool_metadata *pmd, dm_block_t new_size);
  int dm_pool_resize_metadata_dev(struct dm_pool_metadata *pmd, dm_block_t new_size);
  
  /*
   * Flicks the underlying block manager into read only mode, so you know
   * that nothing is changing.
   */
  void dm_pool_metadata_read_only(struct dm_pool_metadata *pmd);
  void dm_pool_metadata_read_write(struct dm_pool_metadata *pmd);
  
  int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd,
  					dm_block_t threshold,
  					dm_sm_threshold_fn fn,
  					void *context);
  
  /*
   * Updates the superblock immediately.
   */
  int dm_pool_metadata_set_needs_check(struct dm_pool_metadata *pmd);
  bool dm_pool_metadata_needs_check(struct dm_pool_metadata *pmd);
  
  /*----------------------------------------------------------------*/
  
  #endif