1 files changed, 398 insertions, 0 deletions

diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h
new file mode 100644
index 000000000..8e69584d5
--- /dev/null
+++ b/fs/btrfs/backref.h
@@ -0,0 +1,398 @@
+/* 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 "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;
+};
+
+struct btrfs_backref_shared_cache {
+	/*
+	 * 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 entries[BTRFS_MAX_LEVEL];
+	bool use_cache;
+};
+
+typedef int (iterate_extent_inodes_t)(u64 inum, u64 offset, u64 root,
+		void *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_root *root, u64 inum, u64 bytenr,
+				u64 extent_gen,
+				struct ulist *roots, struct ulist *tmp,
+				struct btrfs_backref_shared_cache *cache);
+
+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