/* 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 5
/*
* 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.
*/
typedef int (iterate_extent_inodes_t)(u64 inum, u64 offset, u64 num_bytes,
u64 root, void *ctx);
/*
* 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 {
/*
* The address of the extent for which we are doing backref walking.
* Can be either a data extent or a metadata extent.
*
* Must always be set by the top level caller.
*/
u64 bytenr;
/*
* Offset relative to the target extent. This is only used for data
* extents, and it's meaningful because we can have file extent items
* that point only to a section of a data extent ("bookend" extents),
* and we want to filter out any that don't point to a section of the
* data extent containing the given offset.
*
* Must always be set by the top level caller.
*/
u64 extent_item_pos;
/*
* If true and bytenr corresponds to a data extent, then references from
* all file extent items that point to the data extent are considered,
* @extent_item_pos is ignored.
*/
bool ignore_extent_item_pos;
/*
* If true and bytenr corresponds to a data extent, then the inode list
* (each member describing inode number, file offset and root) is not
* added to each reference added to the @refs ulist.
*/
bool skip_inode_ref_list;
/* A valid transaction handle or NULL. */
struct btrfs_trans_handle *trans;
/*
* The file system's info object, can not be NULL.
*
* Must always be set by the top level caller.
*/
struct btrfs_fs_info *fs_info;
/*
* Time sequence acquired from btrfs_get_tree_mod_seq(), in case the
* caller joined the tree mod log to get a consistent view of b+trees
* while we do backref walking, or BTRFS_SEQ_LAST.
* When using BTRFS_SEQ_LAST, delayed refs are not checked and it uses
* commit roots when searching b+trees - this is a special case for
* qgroups used during a transaction commit.
*/
u64 time_seq;
/*
* Used to collect the bytenr of metadata extents that point to the
* target extent.
*/
struct ulist *refs;
/*
* List used to collect the IDs of the roots from which the target
* extent is accessible. Can be NULL in case the caller does not care
* about collecting root IDs.
*/
struct ulist *roots;
/*
* Used by iterate_extent_inodes() and the main backref walk code
* (find_parent_nodes()). Lookup and store functions for an optional
* cache which maps the logical address (bytenr) of leaves to an array
* of root IDs.
*/
bool (*cache_lookup)(u64 leaf_bytenr, void *user_ctx,
const u64 **root_ids_ret, int *root_count_ret);
void (*cache_store)(u64 leaf_bytenr, const struct ulist *root_ids,
void *user_ctx);
/*
* If this is not NULL, then the backref walking code will call this
* for each indirect data extent reference as soon as it finds one,
* before collecting all the remaining backrefs and before resolving
* indirect backrefs. This allows for the caller to terminate backref
* walking as soon as it finds one backref that matches some specific
* criteria. The @cache_lookup and @cache_store callbacks should not
* be NULL in order to use this callback.
*/
iterate_extent_inodes_t *indirect_ref_iterator;
/*
* If this is not NULL, then the backref walking code will call this for
* each extent item it's meant to process before it actually starts
* processing it. If this returns anything other than 0, then it stops
* the backref walking code immediately.
*/
int (*check_extent_item)(u64 bytenr, const struct btrfs_extent_item *ei,
const struct extent_buffer *leaf, void *user_ctx);
/*
* If this is not NULL, then the backref walking code will call this for
* each extent data ref it finds (BTRFS_EXTENT_DATA_REF_KEY keys) before
* processing that data ref. If this callback return false, then it will
* ignore this data ref and it will never resolve the indirect data ref,
* saving time searching for leaves in a fs tree with file extent items
* matching the data ref.
*/
bool (*skip_data_ref)(u64 root, u64 ino, u64 offset, void *user_ctx);
/* Context object to pass to the callbacks defined above. */
void *user_ctx;
};
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;
};
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 {
struct rb_node rbnode;
u64 root_id;
struct btrfs_key key_for_search;
u8 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);
/*
* 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);
/*
* 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.
*/
bool is_reloc;
};
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 (1 << 0)
#define LINK_UPPER (1 << 1)
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)
{
btrfs_panic(fs_info, error,
"Inconsistency in backref cache found at offset %llu",
bytenr);
}
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
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