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1/* SPDX-License-Identifier: GPL-2.0 */2/*3 * Copyright (C) 2011 STRATO. All rights reserved.4 */5 6#ifndef BTRFS_BACKREF_H7#define BTRFS_BACKREF_H8 9#include <linux/types.h>10#include <linux/rbtree.h>11#include <linux/list.h>12#include <linux/slab.h>13#include <uapi/linux/btrfs.h>14#include <uapi/linux/btrfs_tree.h>15#include "messages.h"16#include "locking.h"17#include "disk-io.h"18#include "extent_io.h"19#include "ctree.h"20 21struct extent_inode_elem;22struct ulist;23struct btrfs_extent_item;24struct btrfs_trans_handle;25struct btrfs_fs_info;26 27/*28 * Used by implementations of iterate_extent_inodes_t (see definition below) to29 * signal that backref iteration can stop immediately and no error happened.30 * The value must be non-negative and must not be 0, 1 (which is a common return31 * value from things like btrfs_search_slot() and used internally in the backref32 * walking code) and different from BACKREF_FOUND_SHARED and33 * BACKREF_FOUND_NOT_SHARED34 */35#define BTRFS_ITERATE_EXTENT_INODES_STOP 536 37/*38 * Should return 0 if no errors happened and iteration of backrefs should39 * continue. Can return BTRFS_ITERATE_EXTENT_INODES_STOP or any other non-zero40 * value to immediately stop iteration and possibly signal an error back to41 * the caller.42 */43typedef int (iterate_extent_inodes_t)(u64 inum, u64 offset, u64 num_bytes,44 u64 root, void *ctx);45 46/*47 * Context and arguments for backref walking functions. Some of the fields are48 * to be filled by the caller of such functions while other are filled by the49 * functions themselves, as described below.50 */51struct btrfs_backref_walk_ctx {52 /*53 * The address of the extent for which we are doing backref walking.54 * Can be either a data extent or a metadata extent.55 *56 * Must always be set by the top level caller.57 */58 u64 bytenr;59 /*60 * Offset relative to the target extent. This is only used for data61 * extents, and it's meaningful because we can have file extent items62 * that point only to a section of a data extent ("bookend" extents),63 * and we want to filter out any that don't point to a section of the64 * data extent containing the given offset.65 *66 * Must always be set by the top level caller.67 */68 u64 extent_item_pos;69 /*70 * If true and bytenr corresponds to a data extent, then references from71 * all file extent items that point to the data extent are considered,72 * @extent_item_pos is ignored.73 */74 bool ignore_extent_item_pos;75 /*76 * If true and bytenr corresponds to a data extent, then the inode list77 * (each member describing inode number, file offset and root) is not78 * added to each reference added to the @refs ulist.79 */80 bool skip_inode_ref_list;81 /* A valid transaction handle or NULL. */82 struct btrfs_trans_handle *trans;83 /*84 * The file system's info object, can not be NULL.85 *86 * Must always be set by the top level caller.87 */88 struct btrfs_fs_info *fs_info;89 /*90 * Time sequence acquired from btrfs_get_tree_mod_seq(), in case the91 * caller joined the tree mod log to get a consistent view of b+trees92 * while we do backref walking, or BTRFS_SEQ_LAST.93 * When using BTRFS_SEQ_LAST, delayed refs are not checked and it uses94 * commit roots when searching b+trees - this is a special case for95 * qgroups used during a transaction commit.96 */97 u64 time_seq;98 /*99 * Used to collect the bytenr of metadata extents that point to the100 * target extent.101 */102 struct ulist *refs;103 /*104 * List used to collect the IDs of the roots from which the target105 * extent is accessible. Can be NULL in case the caller does not care106 * about collecting root IDs.107 */108 struct ulist *roots;109 /*110 * Used by iterate_extent_inodes() and the main backref walk code111 * (find_parent_nodes()). Lookup and store functions for an optional112 * cache which maps the logical address (bytenr) of leaves to an array113 * of root IDs.114 */115 bool (*cache_lookup)(u64 leaf_bytenr, void *user_ctx,116 const u64 **root_ids_ret, int *root_count_ret);117 void (*cache_store)(u64 leaf_bytenr, const struct ulist *root_ids,118 void *user_ctx);119 /*120 * If this is not NULL, then the backref walking code will call this121 * for each indirect data extent reference as soon as it finds one,122 * before collecting all the remaining backrefs and before resolving123 * indirect backrefs. This allows for the caller to terminate backref124 * walking as soon as it finds one backref that matches some specific125 * criteria. The @cache_lookup and @cache_store callbacks should not126 * be NULL in order to use this callback.127 */128 iterate_extent_inodes_t *indirect_ref_iterator;129 /*130 * If this is not NULL, then the backref walking code will call this for131 * each extent item it's meant to process before it actually starts132 * processing it. If this returns anything other than 0, then it stops133 * the backref walking code immediately.134 */135 int (*check_extent_item)(u64 bytenr, const struct btrfs_extent_item *ei,136 const struct extent_buffer *leaf, void *user_ctx);137 /*138 * If this is not NULL, then the backref walking code will call this for139 * each extent data ref it finds (BTRFS_EXTENT_DATA_REF_KEY keys) before140 * processing that data ref. If this callback return false, then it will141 * ignore this data ref and it will never resolve the indirect data ref,142 * saving time searching for leaves in a fs tree with file extent items143 * matching the data ref.144 */145 bool (*skip_data_ref)(u64 root, u64 ino, u64 offset, void *user_ctx);146 /* Context object to pass to the callbacks defined above. */147 void *user_ctx;148};149 150struct inode_fs_paths {151 struct btrfs_path *btrfs_path;152 struct btrfs_root *fs_root;153 struct btrfs_data_container *fspath;154};155 156struct btrfs_backref_shared_cache_entry {157 u64 bytenr;158 u64 gen;159 bool is_shared;160};161 162#define BTRFS_BACKREF_CTX_PREV_EXTENTS_SIZE 8163 164struct btrfs_backref_share_check_ctx {165 /* Ulists used during backref walking. */166 struct ulist refs;167 /*168 * The current leaf the caller of btrfs_is_data_extent_shared() is at.169 * Typically the caller (at the moment only fiemap) tries to determine170 * the sharedness of data extents point by file extent items from entire171 * leaves.172 */173 u64 curr_leaf_bytenr;174 /*175 * The previous leaf the caller was at in the previous call to176 * btrfs_is_data_extent_shared(). This may be the same as the current177 * leaf. On the first call it must be 0.178 */179 u64 prev_leaf_bytenr;180 /*181 * A path from a root to a leaf that has a file extent item pointing to182 * a given data extent should never exceed the maximum b+tree height.183 */184 struct btrfs_backref_shared_cache_entry path_cache_entries[BTRFS_MAX_LEVEL];185 bool use_path_cache;186 /*187 * Cache the sharedness result for the last few extents we have found,188 * but only for extents for which we have multiple file extent items189 * that point to them.190 * It's very common to have several file extent items that point to the191 * same extent (bytenr) but with different offsets and lengths. This192 * typically happens for COW writes, partial writes into prealloc193 * extents, NOCOW writes after snapshoting a root, hole punching or194 * reflinking within the same file (less common perhaps).195 * So keep a small cache with the lookup results for the extent pointed196 * by the last few file extent items. This cache is checked, with a197 * linear scan, whenever btrfs_is_data_extent_shared() is called, so198 * it must be small so that it does not negatively affect performance in199 * case we don't have multiple file extent items that point to the same200 * data extent.201 */202 struct {203 u64 bytenr;204 bool is_shared;205 } prev_extents_cache[BTRFS_BACKREF_CTX_PREV_EXTENTS_SIZE];206 /*207 * The slot in the prev_extents_cache array that will be used for208 * storing the sharedness result of a new data extent.209 */210 int prev_extents_cache_slot;211};212 213struct btrfs_backref_share_check_ctx *btrfs_alloc_backref_share_check_ctx(void);214void btrfs_free_backref_share_ctx(struct btrfs_backref_share_check_ctx *ctx);215 216int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,217 struct btrfs_path *path, struct btrfs_key *found_key,218 u64 *flags);219 220int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,221 struct btrfs_key *key, struct btrfs_extent_item *ei,222 u32 item_size, u64 *out_root, u8 *out_level);223 224int iterate_extent_inodes(struct btrfs_backref_walk_ctx *ctx,225 bool search_commit_root,226 iterate_extent_inodes_t *iterate, void *user_ctx);227 228int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,229 struct btrfs_path *path, void *ctx,230 bool ignore_offset);231 232int paths_from_inode(u64 inum, struct inode_fs_paths *ipath);233 234int btrfs_find_all_leafs(struct btrfs_backref_walk_ctx *ctx);235int btrfs_find_all_roots(struct btrfs_backref_walk_ctx *ctx,236 bool skip_commit_root_sem);237char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,238 u32 name_len, unsigned long name_off,239 struct extent_buffer *eb_in, u64 parent,240 char *dest, u32 size);241 242struct btrfs_data_container *init_data_container(u32 total_bytes);243struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,244 struct btrfs_path *path);245void free_ipath(struct inode_fs_paths *ipath);246 247int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,248 u64 start_off, struct btrfs_path *path,249 struct btrfs_inode_extref **ret_extref,250 u64 *found_off);251int btrfs_is_data_extent_shared(struct btrfs_inode *inode, u64 bytenr,252 u64 extent_gen,253 struct btrfs_backref_share_check_ctx *ctx);254 255int __init btrfs_prelim_ref_init(void);256void __cold btrfs_prelim_ref_exit(void);257 258struct prelim_ref {259 struct rb_node rbnode;260 u64 root_id;261 struct btrfs_key key_for_search;262 u8 level;263 int count;264 struct extent_inode_elem *inode_list;265 u64 parent;266 u64 wanted_disk_byte;267};268 269/*270 * Iterate backrefs of one extent.271 *272 * Now it only supports iteration of tree block in commit root.273 */274struct btrfs_backref_iter {275 u64 bytenr;276 struct btrfs_path *path;277 struct btrfs_fs_info *fs_info;278 struct btrfs_key cur_key;279 u32 item_ptr;280 u32 cur_ptr;281 u32 end_ptr;282};283 284struct btrfs_backref_iter *btrfs_backref_iter_alloc(struct btrfs_fs_info *fs_info);285 286/*287 * For metadata with EXTENT_ITEM key (non-skinny) case, the first inline data288 * is btrfs_tree_block_info, without a btrfs_extent_inline_ref header.289 *290 * This helper determines if that's the case.291 */292static inline bool btrfs_backref_has_tree_block_info(293 struct btrfs_backref_iter *iter)294{295 if (iter->cur_key.type == BTRFS_EXTENT_ITEM_KEY &&296 iter->cur_ptr - iter->item_ptr == sizeof(struct btrfs_extent_item))297 return true;298 return false;299}300 301int btrfs_backref_iter_start(struct btrfs_backref_iter *iter, u64 bytenr);302 303int btrfs_backref_iter_next(struct btrfs_backref_iter *iter);304 305/*306 * Backref cache related structures307 *308 * The whole objective of backref_cache is to build a bi-directional map309 * of tree blocks (represented by backref_node) and all their parents.310 */311 312/*313 * Represent a tree block in the backref cache314 */315struct btrfs_backref_node {316 struct {317 struct rb_node rb_node;318 u64 bytenr;319 }; /* Use rb_simple_node for search/insert */320 321 u64 new_bytenr;322 /* Objectid of tree block owner, can be not uptodate */323 u64 owner;324 /* Link to pending, changed or detached list */325 struct list_head list;326 327 /* List of upper level edges, which link this node to its parents */328 struct list_head upper;329 /* List of lower level edges, which link this node to its children */330 struct list_head lower;331 332 /* NULL if this node is not tree root */333 struct btrfs_root *root;334 /* Extent buffer got by COWing the block */335 struct extent_buffer *eb;336 /* Level of the tree block */337 unsigned int level:8;338 /* Is the block in a non-shareable tree */339 unsigned int cowonly:1;340 /* 1 if no child node is in the cache */341 unsigned int lowest:1;342 /* Is the extent buffer locked */343 unsigned int locked:1;344 /* Has the block been processed */345 unsigned int processed:1;346 /* Have backrefs of this block been checked */347 unsigned int checked:1;348 /*349 * 1 if corresponding block has been COWed but some upper level block350 * pointers may not point to the new location351 */352 unsigned int pending:1;353 /* 1 if the backref node isn't connected to any other backref node */354 unsigned int detached:1;355 356 /*357 * For generic purpose backref cache, where we only care if it's a reloc358 * root, doesn't care the source subvolid.359 */360 unsigned int is_reloc_root:1;361};362 363#define LOWER 0364#define UPPER 1365 366/*367 * Represent an edge connecting upper and lower backref nodes.368 */369struct btrfs_backref_edge {370 /*371 * list[LOWER] is linked to btrfs_backref_node::upper of lower level372 * node, and list[UPPER] is linked to btrfs_backref_node::lower of373 * upper level node.374 *375 * Also, build_backref_tree() uses list[UPPER] for pending edges, before376 * linking list[UPPER] to its upper level nodes.377 */378 struct list_head list[2];379 380 /* Two related nodes */381 struct btrfs_backref_node *node[2];382};383 384struct btrfs_backref_cache {385 /* Red black tree of all backref nodes in the cache */386 struct rb_root rb_root;387 /* For passing backref nodes to btrfs_reloc_cow_block */388 struct btrfs_backref_node *path[BTRFS_MAX_LEVEL];389 /*390 * List of blocks that have been COWed but some block pointers in upper391 * level blocks may not reflect the new location392 */393 struct list_head pending[BTRFS_MAX_LEVEL];394 /* List of backref nodes with no child node */395 struct list_head leaves;396 /* List of blocks that have been COWed in current transaction */397 struct list_head changed;398 /* List of detached backref node. */399 struct list_head detached;400 401 u64 last_trans;402 403 int nr_nodes;404 int nr_edges;405 406 /* List of unchecked backref edges during backref cache build */407 struct list_head pending_edge;408 409 /* List of useless backref nodes during backref cache build */410 struct list_head useless_node;411 412 struct btrfs_fs_info *fs_info;413 414 /*415 * Whether this cache is for relocation416 *417 * Reloction backref cache require more info for reloc root compared418 * to generic backref cache.419 */420 bool is_reloc;421};422 423void btrfs_backref_init_cache(struct btrfs_fs_info *fs_info,424 struct btrfs_backref_cache *cache, bool is_reloc);425struct btrfs_backref_node *btrfs_backref_alloc_node(426 struct btrfs_backref_cache *cache, u64 bytenr, int level);427struct btrfs_backref_edge *btrfs_backref_alloc_edge(428 struct btrfs_backref_cache *cache);429 430#define LINK_LOWER (1 << 0)431#define LINK_UPPER (1 << 1)432 433void btrfs_backref_link_edge(struct btrfs_backref_edge *edge,434 struct btrfs_backref_node *lower,435 struct btrfs_backref_node *upper,436 int link_which);437void btrfs_backref_free_node(struct btrfs_backref_cache *cache,438 struct btrfs_backref_node *node);439void btrfs_backref_free_edge(struct btrfs_backref_cache *cache,440 struct btrfs_backref_edge *edge);441void btrfs_backref_unlock_node_buffer(struct btrfs_backref_node *node);442void btrfs_backref_drop_node_buffer(struct btrfs_backref_node *node);443 444void btrfs_backref_cleanup_node(struct btrfs_backref_cache *cache,445 struct btrfs_backref_node *node);446void btrfs_backref_drop_node(struct btrfs_backref_cache *tree,447 struct btrfs_backref_node *node);448 449void btrfs_backref_release_cache(struct btrfs_backref_cache *cache);450 451static inline void btrfs_backref_panic(struct btrfs_fs_info *fs_info,452 u64 bytenr, int error)453{454 btrfs_panic(fs_info, error,455 "Inconsistency in backref cache found at offset %llu",456 bytenr);457}458 459int btrfs_backref_add_tree_node(struct btrfs_trans_handle *trans,460 struct btrfs_backref_cache *cache,461 struct btrfs_path *path,462 struct btrfs_backref_iter *iter,463 struct btrfs_key *node_key,464 struct btrfs_backref_node *cur);465 466int btrfs_backref_finish_upper_links(struct btrfs_backref_cache *cache,467 struct btrfs_backref_node *start);468 469void btrfs_backref_error_cleanup(struct btrfs_backref_cache *cache,470 struct btrfs_backref_node *node);471 472#endif473