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Diffstat (limited to 'fs/btrfs/backref.h')
| -rw-r--r-- | fs/btrfs/backref.h | 556 |
1 files changed, 556 insertions, 0 deletions
diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h new file mode 100644 index 000000000..71d535e03 --- /dev/null +++ b/fs/btrfs/backref.h @@ -0,0 +1,556 @@ +/* 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" + +/* + * 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; + 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); + +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_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 |