/* SPDX-License-Identifier: GPL-2.0 */

  /*
   * Copyright (C) 2011 STRATO.  All rights reserved.

   */

  #ifndef BTRFS_BACKREF_H
  #define BTRFS_BACKREF_H

  #include <linux/btrfs.h>

  #include "ulist.h"

  #include "disk-io.h"

  #include "extent_io.h"

  
  struct inode_fs_paths {
  	struct btrfs_path		*btrfs_path;
  	struct btrfs_root		*fs_root;
  	struct btrfs_data_container	*fspath;
  };
  
  typedef int (iterate_extent_inodes_t)(u64 inum, u64 offset, u64 root,
  		void *ctx);

  int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,

  			struct btrfs_path *path, struct btrfs_key *found_key,
  			u64 *flags);

  
  int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,

  			    struct btrfs_key *key, struct btrfs_extent_item *ei,
  			    u32 item_size, u64 *out_root, u8 *out_level);

  
  int iterate_extent_inodes(struct btrfs_fs_info *fs_info,

  				u64 extent_item_objectid,

  				u64 extent_offset, int search_commit_root,

  				iterate_extent_inodes_t *iterate, void *ctx,
  				bool ignore_offset);

  
  int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
  				struct btrfs_path *path,

  				iterate_extent_inodes_t *iterate, void *ctx,
  				bool ignore_offset);

  
  int paths_from_inode(u64 inum, struct inode_fs_paths *ipath);

  int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
  			 struct btrfs_fs_info *fs_info, u64 bytenr,
  			 u64 time_seq, struct ulist **leafs,
  			 const u64 *extent_item_pos, bool ignore_offset);

  int btrfs_find_all_roots(struct btrfs_trans_handle *trans,

  			 struct btrfs_fs_info *fs_info, u64 bytenr,

  			 u64 time_seq, struct ulist **roots, bool ignore_offset);

  char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
  			u32 name_len, unsigned long name_off,
  			struct extent_buffer *eb_in, u64 parent,
  			char *dest, u32 size);

  struct btrfs_data_container *init_data_container(u32 total_bytes);
  struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
  					struct btrfs_path *path);
  void free_ipath(struct inode_fs_paths *ipath);

  int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
  			  u64 start_off, struct btrfs_path *path,
  			  struct btrfs_inode_extref **ret_extref,
  			  u64 *found_off);

  int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr,
  		struct ulist *roots, struct ulist *tmp_ulist);

  int __init btrfs_prelim_ref_init(void);

  void __cold btrfs_prelim_ref_exit(void);

  
  struct prelim_ref {
  	struct rb_node rbnode;
  	u64 root_id;
  	struct btrfs_key key_for_search;
  	int level;
  	int count;
  	struct extent_inode_elem *inode_list;
  	u64 parent;
  	u64 wanted_disk_byte;
  };

  /*
   * Iterate backrefs of one extent.
   *
   * Now it only supports iteration of tree block in commit root.
   */
  struct btrfs_backref_iter {
  	u64 bytenr;
  	struct btrfs_path *path;
  	struct btrfs_fs_info *fs_info;
  	struct btrfs_key cur_key;
  	u32 item_ptr;
  	u32 cur_ptr;
  	u32 end_ptr;
  };
  
  struct btrfs_backref_iter *btrfs_backref_iter_alloc(
  		struct btrfs_fs_info *fs_info, gfp_t gfp_flag);
  
  static inline void btrfs_backref_iter_free(struct btrfs_backref_iter *iter)
  {
  	if (!iter)
  		return;
  	btrfs_free_path(iter->path);
  	kfree(iter);
  }

  static inline struct extent_buffer *btrfs_backref_get_eb(
  		struct btrfs_backref_iter *iter)
  {
  	if (!iter)
  		return NULL;
  	return iter->path->nodes[0];
  }
  
  /*
   * For metadata with EXTENT_ITEM key (non-skinny) case, the first inline data
   * is btrfs_tree_block_info, without a btrfs_extent_inline_ref header.
   *
   * This helper determines if that's the case.
   */
  static inline bool btrfs_backref_has_tree_block_info(
  		struct btrfs_backref_iter *iter)
  {
  	if (iter->cur_key.type == BTRFS_EXTENT_ITEM_KEY &&
  	    iter->cur_ptr - iter->item_ptr == sizeof(struct btrfs_extent_item))
  		return true;
  	return false;
  }

  int btrfs_backref_iter_start(struct btrfs_backref_iter *iter, u64 bytenr);

  int btrfs_backref_iter_next(struct btrfs_backref_iter *iter);
  
  static inline bool btrfs_backref_iter_is_inline_ref(
  		struct btrfs_backref_iter *iter)
  {
  	if (iter->cur_key.type == BTRFS_EXTENT_ITEM_KEY ||
  	    iter->cur_key.type == BTRFS_METADATA_ITEM_KEY)
  		return true;
  	return false;
  }

  static inline void btrfs_backref_iter_release(struct btrfs_backref_iter *iter)
  {
  	iter->bytenr = 0;
  	iter->item_ptr = 0;
  	iter->cur_ptr = 0;
  	iter->end_ptr = 0;
  	btrfs_release_path(iter->path);
  	memset(&iter->cur_key, 0, sizeof(iter->cur_key));
  }

  /*
   * Backref cache related structures
   *
   * The whole objective of backref_cache is to build a bi-directional map
   * of tree blocks (represented by backref_node) and all their parents.
   */
  
  /*
   * Represent a tree block in the backref cache
   */
  struct btrfs_backref_node {

  	struct {
  		struct rb_node rb_node;
  		u64 bytenr;
  	}; /* Use rb_simple_node for search/insert */

  
  	u64 new_bytenr;
  	/* Objectid of tree block owner, can be not uptodate */
  	u64 owner;
  	/* Link to pending, changed or detached list */
  	struct list_head list;
  
  	/* List of upper level edges, which link this node to its parents */
  	struct list_head upper;
  	/* List of lower level edges, which link this node to its children */
  	struct list_head lower;
  
  	/* NULL if this node is not tree root */
  	struct btrfs_root *root;
  	/* Extent buffer got by COWing the block */
  	struct extent_buffer *eb;
  	/* Level of the tree block */
  	unsigned int level:8;

  	/* Is the block in a non-shareable tree */

  	unsigned int cowonly:1;
  	/* 1 if no child node is in the cache */
  	unsigned int lowest:1;
  	/* Is the extent buffer locked */
  	unsigned int locked:1;
  	/* Has the block been processed */
  	unsigned int processed:1;
  	/* Have backrefs of this block been checked */
  	unsigned int checked:1;
  	/*
  	 * 1 if corresponding block has been COWed but some upper level block
  	 * pointers may not point to the new location
  	 */
  	unsigned int pending:1;
  	/* 1 if the backref node isn't connected to any other backref node */
  	unsigned int detached:1;
  
  	/*
  	 * For generic purpose backref cache, where we only care if it's a reloc
  	 * root, doesn't care the source subvolid.
  	 */
  	unsigned int is_reloc_root:1;
  };
  
  #define LOWER	0
  #define UPPER	1
  
  /*
   * Represent an edge connecting upper and lower backref nodes.
   */
  struct btrfs_backref_edge {
  	/*
  	 * list[LOWER] is linked to btrfs_backref_node::upper of lower level
  	 * node, and list[UPPER] is linked to btrfs_backref_node::lower of
  	 * upper level node.
  	 *
  	 * Also, build_backref_tree() uses list[UPPER] for pending edges, before
  	 * linking list[UPPER] to its upper level nodes.
  	 */
  	struct list_head list[2];
  
  	/* Two related nodes */
  	struct btrfs_backref_node *node[2];
  };
  
  struct btrfs_backref_cache {
  	/* Red black tree of all backref nodes in the cache */
  	struct rb_root rb_root;
  	/* For passing backref nodes to btrfs_reloc_cow_block */
  	struct btrfs_backref_node *path[BTRFS_MAX_LEVEL];
  	/*
  	 * List of blocks that have been COWed but some block pointers in upper
  	 * level blocks may not reflect the new location
  	 */
  	struct list_head pending[BTRFS_MAX_LEVEL];
  	/* List of backref nodes with no child node */
  	struct list_head leaves;
  	/* List of blocks that have been COWed in current transaction */
  	struct list_head changed;
  	/* List of detached backref node. */
  	struct list_head detached;
  
  	u64 last_trans;
  
  	int nr_nodes;
  	int nr_edges;
  
  	/* List of unchecked backref edges during backref cache build */
  	struct list_head pending_edge;
  
  	/* List of useless backref nodes during backref cache build */
  	struct list_head useless_node;
  
  	struct btrfs_fs_info *fs_info;
  
  	/*
  	 * Whether this cache is for relocation
  	 *
  	 * Reloction backref cache require more info for reloc root compared
  	 * to generic backref cache.
  	 */
  	unsigned int is_reloc;
  };

  void btrfs_backref_init_cache(struct btrfs_fs_info *fs_info,
  			      struct btrfs_backref_cache *cache, int is_reloc);

  struct btrfs_backref_node *btrfs_backref_alloc_node(
  		struct btrfs_backref_cache *cache, u64 bytenr, int level);

  struct btrfs_backref_edge *btrfs_backref_alloc_edge(
  		struct btrfs_backref_cache *cache);

  #define		LINK_LOWER	(1 << 0)
  #define		LINK_UPPER	(1 << 1)
  static inline void btrfs_backref_link_edge(struct btrfs_backref_edge *edge,
  					   struct btrfs_backref_node *lower,
  					   struct btrfs_backref_node *upper,
  					   int link_which)
  {
  	ASSERT(upper && lower && upper->level == lower->level + 1);
  	edge->node[LOWER] = lower;
  	edge->node[UPPER] = upper;
  	if (link_which & LINK_LOWER)
  		list_add_tail(&edge->list[LOWER], &lower->upper);
  	if (link_which & LINK_UPPER)
  		list_add_tail(&edge->list[UPPER], &upper->lower);
  }

  static inline void btrfs_backref_free_node(struct btrfs_backref_cache *cache,
  					   struct btrfs_backref_node *node)
  {
  	if (node) {
  		cache->nr_nodes--;
  		btrfs_put_root(node->root);
  		kfree(node);
  	}
  }
  
  static inline void btrfs_backref_free_edge(struct btrfs_backref_cache *cache,
  					   struct btrfs_backref_edge *edge)
  {
  	if (edge) {
  		cache->nr_edges--;
  		kfree(edge);
  	}
  }

  static inline void btrfs_backref_unlock_node_buffer(
  		struct btrfs_backref_node *node)
  {
  	if (node->locked) {
  		btrfs_tree_unlock(node->eb);
  		node->locked = 0;
  	}
  }
  
  static inline void btrfs_backref_drop_node_buffer(
  		struct btrfs_backref_node *node)
  {
  	if (node->eb) {
  		btrfs_backref_unlock_node_buffer(node);
  		free_extent_buffer(node->eb);
  		node->eb = NULL;
  	}
  }
  
  /*
   * Drop the backref node from cache without cleaning up its children
   * edges.
   *
   * This can only be called on node without parent edges.
   * The children edges are still kept as is.
   */
  static inline void btrfs_backref_drop_node(struct btrfs_backref_cache *tree,
  					   struct btrfs_backref_node *node)
  {
  	BUG_ON(!list_empty(&node->upper));
  
  	btrfs_backref_drop_node_buffer(node);
  	list_del(&node->list);
  	list_del(&node->lower);
  	if (!RB_EMPTY_NODE(&node->rb_node))
  		rb_erase(&node->rb_node, &tree->rb_root);
  	btrfs_backref_free_node(tree, node);
  }

  void btrfs_backref_cleanup_node(struct btrfs_backref_cache *cache,
  				struct btrfs_backref_node *node);

  void btrfs_backref_release_cache(struct btrfs_backref_cache *cache);

  static inline void btrfs_backref_panic(struct btrfs_fs_info *fs_info,
  				       u64 bytenr, int errno)
  {
  	btrfs_panic(fs_info, errno,
  		    "Inconsistency in backref cache found at offset %llu",
  		    bytenr);
  }

  int btrfs_backref_add_tree_node(struct btrfs_backref_cache *cache,
  				struct btrfs_path *path,
  				struct btrfs_backref_iter *iter,
  				struct btrfs_key *node_key,
  				struct btrfs_backref_node *cur);

  int btrfs_backref_finish_upper_links(struct btrfs_backref_cache *cache,
  				     struct btrfs_backref_node *start);

  void btrfs_backref_error_cleanup(struct btrfs_backref_cache *cache,
  				 struct btrfs_backref_node *node);

  #endif