[linux-block.git] / fs / btrfs / backref.h

/* 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 "messages.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;
};

struct btrfs_backref_shared_cache_entry {
	u64 bytenr;
	u64 gen;
	bool is_shared;
};

#define BTRFS_BACKREF_CTX_PREV_EXTENTS_SIZE 8

struct btrfs_backref_share_check_ctx {
	/* Ulists used during backref walking. */
	struct ulist refs;
	/*
	 * The current leaf the caller of btrfs_is_data_extent_shared() is at.
	 * Typically the caller (at the moment only fiemap) tries to determine
	 * the sharedness of data extents point by file extent items from entire
	 * leaves.
	 */
	u64 curr_leaf_bytenr;
	/*
	 * The previous leaf the caller was at in the previous call to
	 * btrfs_is_data_extent_shared(). This may be the same as the current
	 * leaf. On the first call it must be 0.
	 */
	u64 prev_leaf_bytenr;
	/*
	 * A path from a root to a leaf that has a file extent item pointing to
	 * a given data extent should never exceed the maximum b+tree height.
	 */
	struct btrfs_backref_shared_cache_entry path_cache_entries[BTRFS_MAX_LEVEL];
	bool use_path_cache;
	/*
	 * Cache the sharedness result for the last few extents we have found,
	 * but only for extents for which we have multiple file extent items
	 * that point to them.
	 * It's very common to have several file extent items that point to the
	 * same extent (bytenr) but with different offsets and lengths. This
	 * typically happens for COW writes, partial writes into prealloc
	 * extents, NOCOW writes after snapshoting a root, hole punching or
	 * reflinking within the same file (less common perhaps).
	 * So keep a small cache with the lookup results for the extent pointed
	 * by the last few file extent items. This cache is checked, with a
	 * linear scan, whenever btrfs_is_data_extent_shared() is called, so
	 * it must be small so that it does not negatively affect performance in
	 * case we don't have multiple file extent items that point to the same
	 * data extent.
	 */
	struct {
		u64 bytenr;
		bool is_shared;
	} prev_extents_cache[BTRFS_BACKREF_CTX_PREV_EXTENTS_SIZE];
	/*
	 * The slot in the prev_extents_cache array that will be used for
	 * storing the sharedness result of a new data extent.
	 */
	int prev_extents_cache_slot;
};

typedef int (iterate_extent_inodes_t)(u64 inum, u64 offset, u64 root,
		void *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_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, 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 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 {
	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) {
		ASSERT(list_empty(&node->list));
		ASSERT(list_empty(&node->lower));
		ASSERT(node->eb == NULL);
		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)
{
	ASSERT(list_empty(&node->upper));

	btrfs_backref_drop_node_buffer(node);
	list_del_init(&node->list);
	list_del_init(&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
Commit	Line	Data
9888c340	1	/* SPDX-License-Identifier: GPL-2.0 */
a542ad1b JS	2	/*
a542ad1b JS	3	* Copyright (C) 2011 STRATO. All rights reserved.
a542ad1b JS	4	*/
a542ad1b JS	5
9888c340 DS	6	#ifndef BTRFS_BACKREF_H
9888c340 DS	7	#define BTRFS_BACKREF_H
a542ad1b	8
55e301fd	9	#include <linux/btrfs.h>
9b569ea0	10	#include "messages.h"
8da6d581	11	#include "ulist.h"
741188d3	12	#include "disk-io.h"
91cb916c	13	#include "extent_io.h"
a542ad1b JS	14
	15	struct inode_fs_paths {
	16	struct btrfs_path *btrfs_path;
	17	struct btrfs_root *fs_root;
	18	struct btrfs_data_container *fspath;
	19	};
	20
12a824dc FM	21	struct btrfs_backref_shared_cache_entry {
	22	u64 bytenr;
	23	u64 gen;
	24	bool is_shared;
	25	};
	26
73e339e6 FM	27	#define BTRFS_BACKREF_CTX_PREV_EXTENTS_SIZE 8
73e339e6 FM	28
61dbb952	29	struct btrfs_backref_share_check_ctx {
84a7949d FM	30	/* Ulists used during backref walking. */
84a7949d FM	31	struct ulist refs;
877c1476 FM	32	/*
	33	* The current leaf the caller of btrfs_is_data_extent_shared() is at.
	34	* Typically the caller (at the moment only fiemap) tries to determine
	35	* the sharedness of data extents point by file extent items from entire
	36	* leaves.
	37	*/
	38	u64 curr_leaf_bytenr;
	39	/*
	40	* The previous leaf the caller was at in the previous call to
	41	* btrfs_is_data_extent_shared(). This may be the same as the current
	42	* leaf. On the first call it must be 0.
	43	*/
	44	u64 prev_leaf_bytenr;
12a824dc FM	45	/*
	46	* A path from a root to a leaf that has a file extent item pointing to
	47	* a given data extent should never exceed the maximum b+tree height.
	48	*/
61dbb952 FM	49	struct btrfs_backref_shared_cache_entry path_cache_entries[BTRFS_MAX_LEVEL];
61dbb952 FM	50	bool use_path_cache;
73e339e6 FM	51	/*
	52	* Cache the sharedness result for the last few extents we have found,
	53	* but only for extents for which we have multiple file extent items
	54	* that point to them.
	55	* It's very common to have several file extent items that point to the
	56	* same extent (bytenr) but with different offsets and lengths. This
	57	* typically happens for COW writes, partial writes into prealloc
	58	* extents, NOCOW writes after snapshoting a root, hole punching or
	59	* reflinking within the same file (less common perhaps).
	60	* So keep a small cache with the lookup results for the extent pointed
	61	* by the last few file extent items. This cache is checked, with a
	62	* linear scan, whenever btrfs_is_data_extent_shared() is called, so
	63	* it must be small so that it does not negatively affect performance in
	64	* case we don't have multiple file extent items that point to the same
	65	* data extent.
	66	*/
	67	struct {
	68	u64 bytenr;
	69	bool is_shared;
	70	} prev_extents_cache[BTRFS_BACKREF_CTX_PREV_EXTENTS_SIZE];
	71	/*
	72	* The slot in the prev_extents_cache array that will be used for
	73	* storing the sharedness result of a new data extent.
	74	*/
	75	int prev_extents_cache_slot;
12a824dc FM	76	};
12a824dc FM	77
a542ad1b JS	78	typedef int (iterate_extent_inodes_t)(u64 inum, u64 offset, u64 root,
a542ad1b JS	79	void *ctx);
a542ad1b	80
84a7949d FM	81	struct btrfs_backref_share_check_ctx *btrfs_alloc_backref_share_check_ctx(void);
	82	void btrfs_free_backref_share_ctx(struct btrfs_backref_share_check_ctx *ctx);
	83
a542ad1b	84	int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
69917e43 LB	85	struct btrfs_path path, struct btrfs_key found_key,
69917e43 LB	86	u64 *flags);
a542ad1b JS	87
a542ad1b JS	88	int tree_backref_for_extent(unsigned long ptr, struct extent_buffer eb,
6eda71d0 LB	89	struct btrfs_key key, struct btrfs_extent_item ei,
6eda71d0 LB	90	u32 item_size, u64 out_root, u8 out_level);
a542ad1b JS	91
a542ad1b JS	92	int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
a542ad1b	93	u64 extent_item_objectid,
7a3ae2f8	94	u64 extent_offset, int search_commit_root,
c995ab3c ZB	95	iterate_extent_inodes_t iterate, void ctx,
c995ab3c ZB	96	bool ignore_offset);
a542ad1b JS	97
a542ad1b JS	98	int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
e3059ec0	99	struct btrfs_path path, void ctx,
c995ab3c	100	bool ignore_offset);
a542ad1b JS	101
	102	int paths_from_inode(u64 inum, struct inode_fs_paths *ipath);
	103
19b546d7 QW	104	int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
	105	struct btrfs_fs_info *fs_info, u64 bytenr,
	106	u64 time_seq, struct ulist **leafs,
	107	const u64 *extent_item_pos, bool ignore_offset);
8da6d581	108	int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
fcebe456	109	struct btrfs_fs_info *fs_info, u64 bytenr,
c7bcbb21	110	u64 time_seq, struct ulist **roots,
8949b9a1	111	bool skip_commit_root_sem);
96b5bd77 JS	112	char btrfs_ref_to_path(struct btrfs_root fs_root, struct btrfs_path *path,
	113	u32 name_len, unsigned long name_off,
	114	struct extent_buffer *eb_in, u64 parent,
	115	char *dest, u32 size);
8da6d581	116
a542ad1b JS	117	struct btrfs_data_container *init_data_container(u32 total_bytes);
	118	struct inode_fs_paths init_ipath(s32 total_bytes, struct btrfs_root fs_root,
	119	struct btrfs_path *path);
	120	void free_ipath(struct inode_fs_paths *ipath);
	121
f186373f MF	122	int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
	123	u64 start_off, struct btrfs_path *path,
	124	struct btrfs_inode_extref **ret_extref,
	125	u64 *found_off);
ceb707da	126	int btrfs_is_data_extent_shared(struct btrfs_inode *inode, u64 bytenr,
b8f164e3	127	u64 extent_gen,
61dbb952	128	struct btrfs_backref_share_check_ctx *ctx);
f186373f	129
b9e9a6cb	130	int __init btrfs_prelim_ref_init(void);
e67c718b	131	void __cold btrfs_prelim_ref_exit(void);
00142756 JM	132
	133	struct prelim_ref {
	134	struct rb_node rbnode;
	135	u64 root_id;
	136	struct btrfs_key key_for_search;
	137	int level;
	138	int count;
	139	struct extent_inode_elem *inode_list;
	140	u64 parent;
	141	u64 wanted_disk_byte;
	142	};
	143
a37f232b QW	144	/*
	145	* Iterate backrefs of one extent.
	146	*
	147	* Now it only supports iteration of tree block in commit root.
	148	*/
	149	struct btrfs_backref_iter {
	150	u64 bytenr;
	151	struct btrfs_path *path;
	152	struct btrfs_fs_info *fs_info;
	153	struct btrfs_key cur_key;
	154	u32 item_ptr;
	155	u32 cur_ptr;
	156	u32 end_ptr;
	157	};
	158
	159	struct btrfs_backref_iter *btrfs_backref_iter_alloc(
	160	struct btrfs_fs_info *fs_info, gfp_t gfp_flag);
	161
	162	static inline void btrfs_backref_iter_free(struct btrfs_backref_iter *iter)
	163	{
	164	if (!iter)
	165	return;
	166	btrfs_free_path(iter->path);
	167	kfree(iter);
	168	}
	169
c39c2ddc QW	170	static inline struct extent_buffer *btrfs_backref_get_eb(
	171	struct btrfs_backref_iter *iter)
	172	{
	173	if (!iter)
	174	return NULL;
	175	return iter->path->nodes[0];
	176	}
	177
	178	/*
	179	* For metadata with EXTENT_ITEM key (non-skinny) case, the first inline data
	180	* is btrfs_tree_block_info, without a btrfs_extent_inline_ref header.
	181	*
	182	* This helper determines if that's the case.
	183	*/
	184	static inline bool btrfs_backref_has_tree_block_info(
	185	struct btrfs_backref_iter *iter)
	186	{
	187	if (iter->cur_key.type == BTRFS_EXTENT_ITEM_KEY &&
	188	iter->cur_ptr - iter->item_ptr == sizeof(struct btrfs_extent_item))
	189	return true;
	190	return false;
	191	}
	192
a37f232b QW	193	int btrfs_backref_iter_start(struct btrfs_backref_iter *iter, u64 bytenr);
a37f232b QW	194
c39c2ddc QW	195	int btrfs_backref_iter_next(struct btrfs_backref_iter *iter);
	196
	197	static inline bool btrfs_backref_iter_is_inline_ref(
	198	struct btrfs_backref_iter *iter)
	199	{
	200	if (iter->cur_key.type == BTRFS_EXTENT_ITEM_KEY \|\|
	201	iter->cur_key.type == BTRFS_METADATA_ITEM_KEY)
	202	return true;
	203	return false;
	204	}
	205
a37f232b QW	206	static inline void btrfs_backref_iter_release(struct btrfs_backref_iter *iter)
	207	{
	208	iter->bytenr = 0;
	209	iter->item_ptr = 0;
	210	iter->cur_ptr = 0;
	211	iter->end_ptr = 0;
	212	btrfs_release_path(iter->path);
	213	memset(&iter->cur_key, 0, sizeof(iter->cur_key));
	214	}
	215
70535441 QW	216	/*
	217	* Backref cache related structures
	218	*
	219	* The whole objective of backref_cache is to build a bi-directional map
	220	* of tree blocks (represented by backref_node) and all their parents.
	221	*/
	222
	223	/*
	224	* Represent a tree block in the backref cache
	225	*/
	226	struct btrfs_backref_node {
e9a28dc5 QW	227	struct {
	228	struct rb_node rb_node;
	229	u64 bytenr;
	230	}; /* Use rb_simple_node for search/insert */
70535441 QW	231
	232	u64 new_bytenr;
	233	/* Objectid of tree block owner, can be not uptodate */
	234	u64 owner;
	235	/* Link to pending, changed or detached list */
	236	struct list_head list;
	237
	238	/* List of upper level edges, which link this node to its parents */
	239	struct list_head upper;
	240	/* List of lower level edges, which link this node to its children */
	241	struct list_head lower;
	242
	243	/* NULL if this node is not tree root */
	244	struct btrfs_root *root;
	245	/* Extent buffer got by COWing the block */
	246	struct extent_buffer *eb;
	247	/* Level of the tree block */
	248	unsigned int level:8;
92a7cc42	249	/* Is the block in a non-shareable tree */
70535441 QW	250	unsigned int cowonly:1;
	251	/* 1 if no child node is in the cache */
	252	unsigned int lowest:1;
	253	/* Is the extent buffer locked */
	254	unsigned int locked:1;
	255	/* Has the block been processed */
	256	unsigned int processed:1;
	257	/* Have backrefs of this block been checked */
	258	unsigned int checked:1;
	259	/*
	260	* 1 if corresponding block has been COWed but some upper level block
	261	* pointers may not point to the new location
	262	*/
	263	unsigned int pending:1;
	264	/* 1 if the backref node isn't connected to any other backref node */
	265	unsigned int detached:1;
	266
	267	/*
	268	* For generic purpose backref cache, where we only care if it's a reloc
	269	* root, doesn't care the source subvolid.
	270	*/
	271	unsigned int is_reloc_root:1;
	272	};
	273
	274	#define LOWER 0
	275	#define UPPER 1
	276
	277	/*
	278	* Represent an edge connecting upper and lower backref nodes.
	279	*/
	280	struct btrfs_backref_edge {
	281	/*
	282	* list[LOWER] is linked to btrfs_backref_node::upper of lower level
	283	* node, and list[UPPER] is linked to btrfs_backref_node::lower of
	284	* upper level node.
	285	*
	286	* Also, build_backref_tree() uses list[UPPER] for pending edges, before
	287	* linking list[UPPER] to its upper level nodes.
	288	*/
	289	struct list_head list[2];
	290
	291	/* Two related nodes */
	292	struct btrfs_backref_node *node[2];
	293	};
	294
	295	struct btrfs_backref_cache {
	296	/* Red black tree of all backref nodes in the cache */
	297	struct rb_root rb_root;
	298	/* For passing backref nodes to btrfs_reloc_cow_block */
	299	struct btrfs_backref_node *path[BTRFS_MAX_LEVEL];
	300	/*
	301	* List of blocks that have been COWed but some block pointers in upper
	302	* level blocks may not reflect the new location
	303	*/
	304	struct list_head pending[BTRFS_MAX_LEVEL];
	305	/* List of backref nodes with no child node */
	306	struct list_head leaves;
	307	/* List of blocks that have been COWed in current transaction */
	308	struct list_head changed;
	309	/* List of detached backref node. */
	310	struct list_head detached;
	311
	312	u64 last_trans;
	313
314	int nr_nodes;
315	int nr_edges;
316
317	/* List of unchecked backref edges during backref cache build */
318	struct list_head pending_edge;
319
320	/* List of useless backref nodes during backref cache build */
321	struct list_head useless_node;
322
323	struct btrfs_fs_info *fs_info;
324
325	/*
326	* Whether this cache is for relocation
327	*
328	* Reloction backref cache require more info for reloc root compared
329	* to generic backref cache.
330	*/
331	unsigned int is_reloc;
332	};
333
584fb121 QW	334	void btrfs_backref_init_cache(struct btrfs_fs_info *fs_info,
584fb121 QW	335	struct btrfs_backref_cache *cache, int is_reloc);
b1818dab QW	336	struct btrfs_backref_node *btrfs_backref_alloc_node(
b1818dab QW	337	struct btrfs_backref_cache *cache, u64 bytenr, int level);
47254d07 QW	338	struct btrfs_backref_edge *btrfs_backref_alloc_edge(
47254d07 QW	339	struct btrfs_backref_cache *cache);
584fb121	340
f39911e5 QW	341	#define LINK_LOWER (1 << 0)
	342	#define LINK_UPPER (1 << 1)
	343	static inline void btrfs_backref_link_edge(struct btrfs_backref_edge *edge,
	344	struct btrfs_backref_node *lower,
	345	struct btrfs_backref_node *upper,
	346	int link_which)
	347	{
	348	ASSERT(upper && lower && upper->level == lower->level + 1);
	349	edge->node[LOWER] = lower;
	350	edge->node[UPPER] = upper;
	351	if (link_which & LINK_LOWER)
	352	list_add_tail(&edge->list[LOWER], &lower->upper);
	353	if (link_which & LINK_UPPER)
	354	list_add_tail(&edge->list[UPPER], &upper->lower);
	355	}
	356
741188d3 QW	357	static inline void btrfs_backref_free_node(struct btrfs_backref_cache *cache,
	358	struct btrfs_backref_node *node)
	359	{
	360	if (node) {
eddda68d JB	361	ASSERT(list_empty(&node->list));
	362	ASSERT(list_empty(&node->lower));
	363	ASSERT(node->eb == NULL);
741188d3 QW	364	cache->nr_nodes--;
	365	btrfs_put_root(node->root);
	366	kfree(node);
	367	}
	368	}
	369
	370	static inline void btrfs_backref_free_edge(struct btrfs_backref_cache *cache,
	371	struct btrfs_backref_edge *edge)
	372	{
	373	if (edge) {
	374	cache->nr_edges--;
	375	kfree(edge);
	376	}
	377	}
	378
b0fe7078 QW	379	static inline void btrfs_backref_unlock_node_buffer(
	380	struct btrfs_backref_node *node)
	381	{
	382	if (node->locked) {
	383	btrfs_tree_unlock(node->eb);
	384	node->locked = 0;
	385	}
	386	}
	387
	388	static inline void btrfs_backref_drop_node_buffer(
	389	struct btrfs_backref_node *node)
	390	{
	391	if (node->eb) {
	392	btrfs_backref_unlock_node_buffer(node);
	393	free_extent_buffer(node->eb);
	394	node->eb = NULL;
	395	}
	396	}
	397
	398	/*
	399	* Drop the backref node from cache without cleaning up its children
	400	* edges.
	401	*
	402	* This can only be called on node without parent edges.
	403	* The children edges are still kept as is.
	404	*/
	405	static inline void btrfs_backref_drop_node(struct btrfs_backref_cache *tree,
	406	struct btrfs_backref_node *node)
	407	{
eddda68d	408	ASSERT(list_empty(&node->upper));
b0fe7078 QW	409
b0fe7078 QW	410	btrfs_backref_drop_node_buffer(node);
eddda68d JB	411	list_del_init(&node->list);
eddda68d JB	412	list_del_init(&node->lower);
b0fe7078 QW	413	if (!RB_EMPTY_NODE(&node->rb_node))
	414	rb_erase(&node->rb_node, &tree->rb_root);
	415	btrfs_backref_free_node(tree, node);
	416	}
	417
023acb07 QW	418	void btrfs_backref_cleanup_node(struct btrfs_backref_cache *cache,
	419	struct btrfs_backref_node *node);
	420
13fe1bdb QW	421	void btrfs_backref_release_cache(struct btrfs_backref_cache *cache);
13fe1bdb QW	422
982c92cb QW	423	static inline void btrfs_backref_panic(struct btrfs_fs_info *fs_info,
	424	u64 bytenr, int errno)
	425	{
	426	btrfs_panic(fs_info, errno,
	427	"Inconsistency in backref cache found at offset %llu",
	428	bytenr);
	429	}
	430
1b60d2ec QW	431	int btrfs_backref_add_tree_node(struct btrfs_backref_cache *cache,
	432	struct btrfs_path *path,
	433	struct btrfs_backref_iter *iter,
	434	struct btrfs_key *node_key,
	435	struct btrfs_backref_node *cur);
	436
fc997ed0 QW	437	int btrfs_backref_finish_upper_links(struct btrfs_backref_cache *cache,
	438	struct btrfs_backref_node *start);
	439
1b23ea18 QW	440	void btrfs_backref_error_cleanup(struct btrfs_backref_cache *cache,
	441	struct btrfs_backref_node *node);
	442
a542ad1b	443	#endif