backref.h | Explore in Territory

/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Copyright (C) 2011 STRATO.  All rights reserved.
 */

#ifndef BTRFS_BACKREF_H
#define BTRFS_BACKREF_H

#include <linux/types.h>
#include <linux/rbtree.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <uapi/linux/btrfs.h>
#include <uapi/linux/btrfs_tree.h>
#include "messages.h"
#include "locking.h"
#include "disk-io.h"
#include "extent_io.h"
#include "ctree.h"

struct extent_inode_elem;
struct ulist;
struct btrfs_extent_item;
struct btrfs_trans_handle;
struct btrfs_fs_info;

/*
 * Used by implementations of iterate_extent_inodes_t (see definition below) to
 * signal that backref iteration can stop immediately and no error happened.
 * The value must be non-negative and must not be 0, 1 (which is a common return
 * value from things like btrfs_search_slot() and used internally in the backref
 * walking code) and different from BACKREF_FOUND_SHARED and
 * BACKREF_FOUND_NOT_SHARED
 */
#define BTRFS_ITERATE_EXTENT_INODES_STOP …

/*
 * Should return 0 if no errors happened and iteration of backrefs should
 * continue. Can return BTRFS_ITERATE_EXTENT_INODES_STOP or any other non-zero
 * value to immediately stop iteration and possibly signal an error back to
 * the caller.
 */
iterate_extent_inodes_t;

/*
 * Context and arguments for backref walking functions. Some of the fields are
 * to be filled by the caller of such functions while other are filled by the
 * functions themselves, as described below.
 */
struct btrfs_backref_walk_ctx { … };

struct inode_fs_paths { … };

struct btrfs_backref_shared_cache_entry { … };

#define BTRFS_BACKREF_CTX_PREV_EXTENTS_SIZE …

struct btrfs_backref_share_check_ctx { … };

struct btrfs_backref_share_check_ctx *btrfs_alloc_backref_share_check_ctx(void);
void btrfs_free_backref_share_ctx(struct btrfs_backref_share_check_ctx *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_backref_walk_ctx *ctx,
			  bool search_commit_root,
			  iterate_extent_inodes_t *iterate, void *user_ctx);

int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
				struct btrfs_path *path, void *ctx,
				bool ignore_offset);

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

int btrfs_find_all_leafs(struct btrfs_backref_walk_ctx *ctx);
int btrfs_find_all_roots(struct btrfs_backref_walk_ctx *ctx,
			 bool skip_commit_root_sem);
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_is_data_extent_shared(struct btrfs_inode *inode, u64 bytenr,
				u64 extent_gen,
				struct btrfs_backref_share_check_ctx *ctx);

int __init btrfs_prelim_ref_init(void);
void __cold btrfs_prelim_ref_exit(void);

struct prelim_ref { … };

/*
 * Iterate backrefs of one extent.
 *
 * Now it only supports iteration of tree block in commit root.
 */
struct btrfs_backref_iter { … };

struct btrfs_backref_iter *btrfs_backref_iter_alloc(struct btrfs_fs_info *fs_info);

/*
 * 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)
{ … }

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

int btrfs_backref_iter_next(struct btrfs_backref_iter *iter);

/*
 * 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 { … };

#define LOWER …
#define UPPER …

/*
 * Represent an edge connecting upper and lower backref nodes.
 */
struct btrfs_backref_edge { … };

struct btrfs_backref_cache { … };

void btrfs_backref_init_cache(struct btrfs_fs_info *fs_info,
			      struct btrfs_backref_cache *cache, bool 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 …
#define LINK_UPPER …

void btrfs_backref_link_edge(struct btrfs_backref_edge *edge,
			     struct btrfs_backref_node *lower,
			     struct btrfs_backref_node *upper,
			     int link_which);
void btrfs_backref_free_node(struct btrfs_backref_cache *cache,
			     struct btrfs_backref_node *node);
void btrfs_backref_free_edge(struct btrfs_backref_cache *cache,
			     struct btrfs_backref_edge *edge);
void btrfs_backref_unlock_node_buffer(struct btrfs_backref_node *node);
void btrfs_backref_drop_node_buffer(struct btrfs_backref_node *node);

void btrfs_backref_cleanup_node(struct btrfs_backref_cache *cache,
				struct btrfs_backref_node *node);
void btrfs_backref_drop_node(struct btrfs_backref_cache *tree,
			     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 error)
{ … }

int btrfs_backref_add_tree_node(struct btrfs_trans_handle *trans,
				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
linux/fs/btrfs/backref.h
