/* 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 snapshotting 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, 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); DEFINE_FREE(inode_fs_paths, struct inode_fs_paths *, if (_T) { kvfree(_T->fspath); kfree(_T); }) 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 { union{ /* Use rb_simple_node for search/insert */ struct { struct rb_node rb_node; u64 bytenr; }; struct rb_simple_node simple_node; }; /* * This is a sanity check, whenever we COW a block we will update * new_bytenr with it's current location, and we will check this in * various places to validate that the cache makes sense, it shouldn't * be used for anything else. */ 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 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]; 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 * * Relocation 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); 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
