fs/btrfs/delayed-ref.h - linux - Git at Google

 /* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2008 Oracle.  All rights reserved.
  */

 #ifndef BTRFS_DELAYED_REF_H
 #define BTRFS_DELAYED_REF_H

 #include <linux/types.h>
 #include <linux/refcount.h>
 #include <linux/list.h>
 #include <linux/rbtree.h>
 #include <linux/mutex.h>
 #include <linux/spinlock.h>
 #include <linux/slab.h>
 #include <uapi/linux/btrfs_tree.h>

 struct btrfs_trans_handle;
 struct btrfs_fs_info;

 /* these are the possible values of struct btrfs_delayed_ref_node->action */
 enum btrfs_delayed_ref_action {
 	/* Add one backref to the tree */
 	BTRFS_ADD_DELAYED_REF = 1,
 	/* Delete one backref from the tree */
 	BTRFS_DROP_DELAYED_REF,
 	/* Record a full extent allocation */
 	BTRFS_ADD_DELAYED_EXTENT,
 	/* Not changing ref count on head ref */
 	BTRFS_UPDATE_DELAYED_HEAD,
 } __packed;

 struct btrfs_data_ref {
 	/* For EXTENT_DATA_REF */

 	/* Inode which refers to this data extent */
 	u64 objectid;

 	/*
 	 * file_offset - extent_offset
 	 *
 	 * file_offset is the key.offset of the EXTENT_DATA key.
 	 * extent_offset is btrfs_file_extent_offset() of the EXTENT_DATA data.
 	 */
 	u64 offset;
 };

 struct btrfs_tree_ref {
 	/*
 	 * Level of this tree block.
 	 *
 	 * Shared for skinny (TREE_BLOCK_REF) and normal tree ref.
 	 */
 	int level;

 	/* For non-skinny metadata, no special member needed */
 };

 struct btrfs_delayed_ref_node {
 	struct rb_node ref_node;
 	/*
 	 * If action is BTRFS_ADD_DELAYED_REF, also link this node to
 	 * ref_head->ref_add_list, then we do not need to iterate the
 	 * refs rbtree in the corresponding delayed ref head
 	 * (struct btrfs_delayed_ref_head::ref_tree).
 	 */
 	struct list_head add_list;

 	/* the starting bytenr of the extent */
 	u64 bytenr;

 	/* the size of the extent */
 	u64 num_bytes;

 	/* seq number to keep track of insertion order */
 	u64 seq;

 	/* The ref_root for this ref */
 	u64 ref_root;

 	/*
 	 * The parent for this ref, if this isn't set the ref_root is the
 	 * reference owner.
 	 */
 	u64 parent;

 	/* ref count on this data structure */
 	refcount_t refs;

 	/*
 	 * how many refs is this entry adding or deleting.  For
 	 * head refs, this may be a negative number because it is keeping
 	 * track of the total mods done to the reference count.
 	 * For individual refs, this will always be a positive number
 	 *
 	 * It may be more than one, since it is possible for a single
 	 * parent to have more than one ref on an extent
 	 */
 	int ref_mod;

 	unsigned int action:8;
 	unsigned int type:8;

 	union {
 		struct btrfs_tree_ref tree_ref;
 		struct btrfs_data_ref data_ref;
 	};
 };

 struct btrfs_delayed_extent_op {
 	struct btrfs_disk_key key;
 	bool update_key;
 	bool update_flags;
 	u64 flags_to_set;
 };

 /*
  * the head refs are used to hold a lock on a given extent, which allows us
  * to make sure that only one process is running the delayed refs
  * at a time for a single extent.  They also store the sum of all the
  * reference count modifications we've queued up.
  */
 struct btrfs_delayed_ref_head {
 	u64 bytenr;
 	u64 num_bytes;
 	/*
 	 * the mutex is held while running the refs, and it is also
 	 * held when checking the sum of reference modifications.
 	 */
 	struct mutex mutex;

 	refcount_t refs;

 	/* Protects 'ref_tree' and 'ref_add_list'. */
 	spinlock_t lock;
 	struct rb_root_cached ref_tree;
 	/* accumulate add BTRFS_ADD_DELAYED_REF nodes to this ref_add_list. */
 	struct list_head ref_add_list;

 	struct btrfs_delayed_extent_op *extent_op;

 	/*
 	 * This is used to track the final ref_mod from all the refs associated
 	 * with this head ref, this is not adjusted as delayed refs are run,
 	 * this is meant to track if we need to do the csum accounting or not.
 	 */
 	int total_ref_mod;

 	/*
 	 * This is the current outstanding mod references for this bytenr.  This
 	 * is used with lookup_extent_info to get an accurate reference count
 	 * for a bytenr, so it is adjusted as delayed refs are run so that any
 	 * on disk reference count + ref_mod is accurate.
 	 */
 	int ref_mod;

 	/*
 	 * The root that triggered the allocation when must_insert_reserved is
 	 * set to true.
 	 */
 	u64 owning_root;

 	/*
 	 * Track reserved bytes when setting must_insert_reserved.  On success
 	 * or cleanup, we will need to free the reservation.
 	 */
 	u64 reserved_bytes;

 	/* Tree block level, for metadata only. */
 	u8 level;

 	/*
 	 * when a new extent is allocated, it is just reserved in memory
 	 * The actual extent isn't inserted into the extent allocation tree
 	 * until the delayed ref is processed.  must_insert_reserved is
 	 * used to flag a delayed ref so the accounting can be updated
 	 * when a full insert is done.
 	 *
 	 * It is possible the extent will be freed before it is ever
 	 * inserted into the extent allocation tree.  In this case
 	 * we need to update the in ram accounting to properly reflect
 	 * the free has happened.
 	 */
 	bool must_insert_reserved;

 	bool is_data;
 	bool is_system;
 	bool processing;
 	/*
 	 * Indicate if it's currently in the data structure that tracks head
 	 * refs (struct btrfs_delayed_ref_root::head_refs).
 	 */
 	bool tracked;
 };

 enum btrfs_delayed_ref_flags {
 	/* Indicate that we are flushing delayed refs for the commit */
 	BTRFS_DELAYED_REFS_FLUSHING,
 };

 struct btrfs_delayed_ref_root {
 	/*
 	 * Track head references.
 	 * The keys correspond to the logical address of the extent ("bytenr")
 	 * right shifted by fs_info->sectorsize_bits. This is both to get a more
 	 * dense index space (optimizes xarray structure) and because indexes in
 	 * xarrays are of "unsigned long" type, meaning they are 32 bits wide on
 	 * 32 bits platforms, limiting the extent range to 4G which is too low
 	 * and makes it unusable (truncated index values) on 32 bits platforms.
 	 * Protected by the spinlock 'lock' defined below.
 	 */
 	struct xarray head_refs;

 	/*
 	 * Track dirty extent records.
 	 * The keys correspond to the logical address of the extent ("bytenr")
 	 * right shifted by fs_info->sectorsize_bits, for same reasons as above.
 	 */
 	struct xarray dirty_extents;

 	/*
 	 * Protects the xarray head_refs, its entries and the following fields:
 	 * num_heads, num_heads_ready, pending_csums and run_delayed_start.
 	 */
 	spinlock_t lock;

 	/* Total number of head refs, protected by the spinlock 'lock'. */
 	unsigned long num_heads;

 	/*
 	 * Total number of head refs ready for processing, protected by the
 	 * spinlock 'lock'.
 	 */
 	unsigned long num_heads_ready;

 	/*
 	 * Track space reserved for deleting csums of data extents.
 	 * Protected by the spinlock 'lock'.
 	 */
 	u64 pending_csums;

 	unsigned long flags;

 	/*
 	 * Track from which bytenr to start searching ref heads.
 	 * Protected by the spinlock 'lock'.
 	 */
 	u64 run_delayed_start;

 	/*
 	 * To make qgroup to skip given root.
 	 * This is for snapshot, as btrfs_qgroup_inherit() will manually
 	 * modify counters for snapshot and its source, so we should skip
 	 * the snapshot in new_root/old_roots or it will get calculated twice
 	 */
 	u64 qgroup_to_skip;
 };

 enum btrfs_ref_type {
 	BTRFS_REF_NOT_SET,
 	BTRFS_REF_DATA,
 	BTRFS_REF_METADATA,
 	BTRFS_REF_LAST,
 } __packed;

 struct btrfs_ref {
 	enum btrfs_ref_type type;
 	enum btrfs_delayed_ref_action action;

 	/*
 	 * Whether this extent should go through qgroup record.
 	 *
 	 * Normally false, but for certain cases like delayed subtree scan,
 	 * setting this flag can hugely reduce qgroup overhead.
 	 */
 	bool skip_qgroup;

 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
 	/* Through which root is this modification. */
 	u64 real_root;
 #endif
 	u64 bytenr;
 	u64 num_bytes;
 	u64 owning_root;

 	/*
 	 * The root that owns the reference for this reference, this will be set
 	 * or ->parent will be set, depending on what type of reference this is.
 	 */
 	u64 ref_root;

 	/* Bytenr of the parent tree block */
 	u64 parent;
 	union {
 		struct btrfs_data_ref data_ref;
 		struct btrfs_tree_ref tree_ref;
 	};
 };

 extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
 extern struct kmem_cache *btrfs_delayed_ref_node_cachep;
 extern struct kmem_cache *btrfs_delayed_extent_op_cachep;

 int __init btrfs_delayed_ref_init(void);
 void __cold btrfs_delayed_ref_exit(void);

 static inline u64 btrfs_calc_delayed_ref_bytes(const struct btrfs_fs_info *fs_info,
 					       int num_delayed_refs)
 {
 	u64 num_bytes;

 	num_bytes = btrfs_calc_insert_metadata_size(fs_info, num_delayed_refs);

 	/*
 	 * We have to check the mount option here because we could be enabling
 	 * the free space tree for the first time and don't have the compat_ro
 	 * option set yet.
 	 *
 	 * We need extra reservations if we have the free space tree because
 	 * we'll have to modify that tree as well.
 	 */
 	if (btrfs_test_opt(fs_info, FREE_SPACE_TREE))
 		num_bytes *= 2;

 	return num_bytes;
 }

 static inline u64 btrfs_calc_delayed_ref_csum_bytes(const struct btrfs_fs_info *fs_info,
 						    int num_csum_items)
 {
 	/*
 	 * Deleting csum items does not result in new nodes/leaves and does not
 	 * require changing the free space tree, only the csum tree, so this is
 	 * all we need.
 	 */
 	return btrfs_calc_metadata_size(fs_info, num_csum_items);
 }

 void btrfs_init_tree_ref(struct btrfs_ref *generic_ref, int level, u64 mod_root,
 			 bool skip_qgroup);
 void btrfs_init_data_ref(struct btrfs_ref *generic_ref, u64 ino, u64 offset,
 			 u64 mod_root, bool skip_qgroup);

 static inline struct btrfs_delayed_extent_op *
 btrfs_alloc_delayed_extent_op(void)
 {
 	return kmem_cache_alloc(btrfs_delayed_extent_op_cachep, GFP_NOFS);
 }

 static inline void
 btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op *op)
 {
 	if (op)
 		kmem_cache_free(btrfs_delayed_extent_op_cachep, op);
 }

 void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref);

 static inline u64 btrfs_ref_head_to_space_flags(
 				struct btrfs_delayed_ref_head *head_ref)
 {
 	if (head_ref->is_data)
 		return BTRFS_BLOCK_GROUP_DATA;
 	else if (head_ref->is_system)
 		return BTRFS_BLOCK_GROUP_SYSTEM;
 	return BTRFS_BLOCK_GROUP_METADATA;
 }

 static inline void btrfs_put_delayed_ref_head(struct btrfs_delayed_ref_head *head)
 {
 	if (refcount_dec_and_test(&head->refs))
 		kmem_cache_free(btrfs_delayed_ref_head_cachep, head);
 }

 int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
 			       struct btrfs_ref *generic_ref,
 			       struct btrfs_delayed_extent_op *extent_op);
 int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
 			       struct btrfs_ref *generic_ref,
 			       u64 reserved);
 int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans,
 				u64 bytenr, u64 num_bytes, u8 level,
 				struct btrfs_delayed_extent_op *extent_op);
 void btrfs_merge_delayed_refs(struct btrfs_fs_info *fs_info,
 			      struct btrfs_delayed_ref_root *delayed_refs,
 			      struct btrfs_delayed_ref_head *head);

 struct btrfs_delayed_ref_head *
 btrfs_find_delayed_ref_head(const struct btrfs_fs_info *fs_info,
 			    struct btrfs_delayed_ref_root *delayed_refs,
 			    u64 bytenr);
 static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
 {
 	mutex_unlock(&head->mutex);
 }
 void btrfs_delete_ref_head(const struct btrfs_fs_info *fs_info,
 			   struct btrfs_delayed_ref_root *delayed_refs,
 			   struct btrfs_delayed_ref_head *head);

 struct btrfs_delayed_ref_head *btrfs_select_ref_head(
 		const struct btrfs_fs_info *fs_info,
 		struct btrfs_delayed_ref_root *delayed_refs);
 void btrfs_unselect_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
 			     struct btrfs_delayed_ref_head *head);

 int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info, u64 seq);

 void btrfs_delayed_refs_rsv_release(struct btrfs_fs_info *fs_info, int nr_refs, int nr_csums);
 void btrfs_update_delayed_refs_rsv(struct btrfs_trans_handle *trans);
 void btrfs_inc_delayed_refs_rsv_bg_inserts(struct btrfs_fs_info *fs_info);
 void btrfs_dec_delayed_refs_rsv_bg_inserts(struct btrfs_fs_info *fs_info);
 void btrfs_inc_delayed_refs_rsv_bg_updates(struct btrfs_fs_info *fs_info);
 void btrfs_dec_delayed_refs_rsv_bg_updates(struct btrfs_fs_info *fs_info);
 int btrfs_delayed_refs_rsv_refill(struct btrfs_fs_info *fs_info,
 				  enum btrfs_reserve_flush_enum flush);
 bool btrfs_check_space_for_delayed_refs(struct btrfs_fs_info *fs_info);
 bool btrfs_find_delayed_tree_ref(struct btrfs_delayed_ref_head *head,
 				 u64 root, u64 parent);
 void btrfs_destroy_delayed_refs(struct btrfs_transaction *trans);

 static inline u64 btrfs_delayed_ref_owner(struct btrfs_delayed_ref_node *node)
 {
 	if (node->type == BTRFS_EXTENT_DATA_REF_KEY ||
 	    node->type == BTRFS_SHARED_DATA_REF_KEY)
 		return node->data_ref.objectid;
 	return node->tree_ref.level;
 }

 static inline u64 btrfs_delayed_ref_offset(struct btrfs_delayed_ref_node *node)
 {
 	if (node->type == BTRFS_EXTENT_DATA_REF_KEY ||
 	    node->type == BTRFS_SHARED_DATA_REF_KEY)
 		return node->data_ref.offset;
 	return 0;
 }

 static inline u8 btrfs_ref_type(struct btrfs_ref *ref)
 {
 	ASSERT(ref->type == BTRFS_REF_DATA || ref->type == BTRFS_REF_METADATA);

 	if (ref->type == BTRFS_REF_DATA) {
 		if (ref->parent)
 			return BTRFS_SHARED_DATA_REF_KEY;
 		else
 			return BTRFS_EXTENT_DATA_REF_KEY;
 	} else {
 		if (ref->parent)
 			return BTRFS_SHARED_BLOCK_REF_KEY;
 		else
 			return BTRFS_TREE_BLOCK_REF_KEY;
 	}

 	return 0;
 }

 #endif
	/* SPDX-License-Identifier: GPL-2.0 */
	/*
	* Copyright (C) 2008 Oracle. All rights reserved.
	*/

	#ifndef BTRFS_DELAYED_REF_H
	#define BTRFS_DELAYED_REF_H

	#include <linux/types.h>
	#include <linux/refcount.h>
	#include <linux/list.h>
	#include <linux/rbtree.h>
	#include <linux/mutex.h>
	#include <linux/spinlock.h>
	#include <linux/slab.h>
	#include <uapi/linux/btrfs_tree.h>

	struct btrfs_trans_handle;
	struct btrfs_fs_info;

	/* these are the possible values of struct btrfs_delayed_ref_node->action */
	enum btrfs_delayed_ref_action {
	/* Add one backref to the tree */
	BTRFS_ADD_DELAYED_REF = 1,
	/* Delete one backref from the tree */
	BTRFS_DROP_DELAYED_REF,
	/* Record a full extent allocation */
	BTRFS_ADD_DELAYED_EXTENT,
	/* Not changing ref count on head ref */
	BTRFS_UPDATE_DELAYED_HEAD,
	} __packed;

	struct btrfs_data_ref {
	/* For EXTENT_DATA_REF */

	/* Inode which refers to this data extent */
	u64 objectid;

	/*
	* file_offset - extent_offset
	*
	* file_offset is the key.offset of the EXTENT_DATA key.
	* extent_offset is btrfs_file_extent_offset() of the EXTENT_DATA data.
	*/
	u64 offset;
	};

	struct btrfs_tree_ref {
	/*
	* Level of this tree block.
	*
	* Shared for skinny (TREE_BLOCK_REF) and normal tree ref.
	*/
	int level;

	/* For non-skinny metadata, no special member needed */
	};

	struct btrfs_delayed_ref_node {
	struct rb_node ref_node;
	/*
	* If action is BTRFS_ADD_DELAYED_REF, also link this node to
	* ref_head->ref_add_list, then we do not need to iterate the
	* refs rbtree in the corresponding delayed ref head
	* (struct btrfs_delayed_ref_head::ref_tree).
	*/
	struct list_head add_list;

	/* the starting bytenr of the extent */
	u64 bytenr;

	/* the size of the extent */
	u64 num_bytes;

	/* seq number to keep track of insertion order */
	u64 seq;

	/* The ref_root for this ref */
	u64 ref_root;

	/*
	* The parent for this ref, if this isn't set the ref_root is the
	* reference owner.
	*/
	u64 parent;

	/* ref count on this data structure */
	refcount_t refs;

	/*
	* how many refs is this entry adding or deleting. For
	* head refs, this may be a negative number because it is keeping
	* track of the total mods done to the reference count.
	* For individual refs, this will always be a positive number
	*
	* It may be more than one, since it is possible for a single
	* parent to have more than one ref on an extent
	*/
	int ref_mod;

	unsigned int action:8;
	unsigned int type:8;

	union {
	struct btrfs_tree_ref tree_ref;
	struct btrfs_data_ref data_ref;
	};
	};

	struct btrfs_delayed_extent_op {
	struct btrfs_disk_key key;
	bool update_key;
	bool update_flags;
	u64 flags_to_set;
	};

	/*
	* the head refs are used to hold a lock on a given extent, which allows us
	* to make sure that only one process is running the delayed refs
	* at a time for a single extent. They also store the sum of all the
	* reference count modifications we've queued up.
	*/
	struct btrfs_delayed_ref_head {
	u64 bytenr;
	u64 num_bytes;
	/*
	* the mutex is held while running the refs, and it is also
	* held when checking the sum of reference modifications.
	*/
	struct mutex mutex;

	refcount_t refs;

	/* Protects 'ref_tree' and 'ref_add_list'. */
	spinlock_t lock;
	struct rb_root_cached ref_tree;
	/* accumulate add BTRFS_ADD_DELAYED_REF nodes to this ref_add_list. */
	struct list_head ref_add_list;

	struct btrfs_delayed_extent_op *extent_op;

	/*
	* This is used to track the final ref_mod from all the refs associated
	* with this head ref, this is not adjusted as delayed refs are run,
	* this is meant to track if we need to do the csum accounting or not.
	*/
	int total_ref_mod;

	/*
	* This is the current outstanding mod references for this bytenr. This
	* is used with lookup_extent_info to get an accurate reference count
	* for a bytenr, so it is adjusted as delayed refs are run so that any
	* on disk reference count + ref_mod is accurate.
	*/
	int ref_mod;

	/*
	* The root that triggered the allocation when must_insert_reserved is
	* set to true.
	*/
	u64 owning_root;

	/*
	* Track reserved bytes when setting must_insert_reserved. On success
	* or cleanup, we will need to free the reservation.
	*/
	u64 reserved_bytes;

	/* Tree block level, for metadata only. */
	u8 level;

	/*
	* when a new extent is allocated, it is just reserved in memory
	* The actual extent isn't inserted into the extent allocation tree
	* until the delayed ref is processed. must_insert_reserved is
	* used to flag a delayed ref so the accounting can be updated
	* when a full insert is done.
	*
	* It is possible the extent will be freed before it is ever
	* inserted into the extent allocation tree. In this case
	* we need to update the in ram accounting to properly reflect
	* the free has happened.
	*/
	bool must_insert_reserved;

	bool is_data;
	bool is_system;
	bool processing;
	/*
	* Indicate if it's currently in the data structure that tracks head
	* refs (struct btrfs_delayed_ref_root::head_refs).
	*/
	bool tracked;
	};

	enum btrfs_delayed_ref_flags {
	/* Indicate that we are flushing delayed refs for the commit */
	BTRFS_DELAYED_REFS_FLUSHING,
	};

	struct btrfs_delayed_ref_root {
	/*
	* Track head references.
	* The keys correspond to the logical address of the extent ("bytenr")
	* right shifted by fs_info->sectorsize_bits. This is both to get a more
	* dense index space (optimizes xarray structure) and because indexes in
	* xarrays are of "unsigned long" type, meaning they are 32 bits wide on
	* 32 bits platforms, limiting the extent range to 4G which is too low
	* and makes it unusable (truncated index values) on 32 bits platforms.
	* Protected by the spinlock 'lock' defined below.
	*/
	struct xarray head_refs;

	/*
	* Track dirty extent records.
	* The keys correspond to the logical address of the extent ("bytenr")
	* right shifted by fs_info->sectorsize_bits, for same reasons as above.
	*/
	struct xarray dirty_extents;

	/*
	* Protects the xarray head_refs, its entries and the following fields:
	* num_heads, num_heads_ready, pending_csums and run_delayed_start.
	*/
	spinlock_t lock;

	/* Total number of head refs, protected by the spinlock 'lock'. */
	unsigned long num_heads;

	/*
	* Total number of head refs ready for processing, protected by the
	* spinlock 'lock'.
	*/
	unsigned long num_heads_ready;

	/*
	* Track space reserved for deleting csums of data extents.
	* Protected by the spinlock 'lock'.
	*/
	u64 pending_csums;

	unsigned long flags;

	/*
	* Track from which bytenr to start searching ref heads.
	* Protected by the spinlock 'lock'.
	*/
	u64 run_delayed_start;

	/*
	* To make qgroup to skip given root.
	* This is for snapshot, as btrfs_qgroup_inherit() will manually
	* modify counters for snapshot and its source, so we should skip
	* the snapshot in new_root/old_roots or it will get calculated twice
	*/
	u64 qgroup_to_skip;
	};

	enum btrfs_ref_type {
	BTRFS_REF_NOT_SET,
	BTRFS_REF_DATA,
	BTRFS_REF_METADATA,
	BTRFS_REF_LAST,
	} __packed;

	struct btrfs_ref {
	enum btrfs_ref_type type;
	enum btrfs_delayed_ref_action action;

	/*
	* Whether this extent should go through qgroup record.
	*
	* Normally false, but for certain cases like delayed subtree scan,
	* setting this flag can hugely reduce qgroup overhead.
	*/
	bool skip_qgroup;

	#ifdef CONFIG_BTRFS_FS_REF_VERIFY
	/* Through which root is this modification. */
	u64 real_root;
	#endif
	u64 bytenr;
	u64 num_bytes;
	u64 owning_root;

	/*
	* The root that owns the reference for this reference, this will be set
	* or ->parent will be set, depending on what type of reference this is.
	*/
	u64 ref_root;

	/* Bytenr of the parent tree block */
	u64 parent;
	union {
	struct btrfs_data_ref data_ref;
	struct btrfs_tree_ref tree_ref;
	};
	};

	extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
	extern struct kmem_cache *btrfs_delayed_ref_node_cachep;
	extern struct kmem_cache *btrfs_delayed_extent_op_cachep;

	int __init btrfs_delayed_ref_init(void);
	void __cold btrfs_delayed_ref_exit(void);

	static inline u64 btrfs_calc_delayed_ref_bytes(const struct btrfs_fs_info *fs_info,
	int num_delayed_refs)
	{
	u64 num_bytes;

	num_bytes = btrfs_calc_insert_metadata_size(fs_info, num_delayed_refs);

	/*
	* We have to check the mount option here because we could be enabling
	* the free space tree for the first time and don't have the compat_ro
	* option set yet.
	*
	* We need extra reservations if we have the free space tree because
	* we'll have to modify that tree as well.
	*/
	if (btrfs_test_opt(fs_info, FREE_SPACE_TREE))
	num_bytes *= 2;

	return num_bytes;
	}

	static inline u64 btrfs_calc_delayed_ref_csum_bytes(const struct btrfs_fs_info *fs_info,
	int num_csum_items)
	{
	/*
	* Deleting csum items does not result in new nodes/leaves and does not
	* require changing the free space tree, only the csum tree, so this is
	* all we need.
	*/
	return btrfs_calc_metadata_size(fs_info, num_csum_items);
	}

	void btrfs_init_tree_ref(struct btrfs_ref *generic_ref, int level, u64 mod_root,
	bool skip_qgroup);
	void btrfs_init_data_ref(struct btrfs_ref *generic_ref, u64 ino, u64 offset,
	u64 mod_root, bool skip_qgroup);

	static inline struct btrfs_delayed_extent_op *
	btrfs_alloc_delayed_extent_op(void)
	{
	return kmem_cache_alloc(btrfs_delayed_extent_op_cachep, GFP_NOFS);
	}

	static inline void
	btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op *op)
	{
	if (op)
	kmem_cache_free(btrfs_delayed_extent_op_cachep, op);
	}

	void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref);

	static inline u64 btrfs_ref_head_to_space_flags(
	struct btrfs_delayed_ref_head *head_ref)
	{
	if (head_ref->is_data)
	return BTRFS_BLOCK_GROUP_DATA;
	else if (head_ref->is_system)
	return BTRFS_BLOCK_GROUP_SYSTEM;
	return BTRFS_BLOCK_GROUP_METADATA;
	}

	static inline void btrfs_put_delayed_ref_head(struct btrfs_delayed_ref_head *head)
	{
	if (refcount_dec_and_test(&head->refs))
	kmem_cache_free(btrfs_delayed_ref_head_cachep, head);
	}

	int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
	struct btrfs_ref *generic_ref,
	struct btrfs_delayed_extent_op *extent_op);
	int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
	struct btrfs_ref *generic_ref,
	u64 reserved);
	int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans,
	u64 bytenr, u64 num_bytes, u8 level,
	struct btrfs_delayed_extent_op *extent_op);
	void btrfs_merge_delayed_refs(struct btrfs_fs_info *fs_info,
	struct btrfs_delayed_ref_root *delayed_refs,
	struct btrfs_delayed_ref_head *head);

	struct btrfs_delayed_ref_head *
	btrfs_find_delayed_ref_head(const struct btrfs_fs_info *fs_info,
	struct btrfs_delayed_ref_root *delayed_refs,
	u64 bytenr);
	static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
	{
	mutex_unlock(&head->mutex);
	}
	void btrfs_delete_ref_head(const struct btrfs_fs_info *fs_info,
	struct btrfs_delayed_ref_root *delayed_refs,
	struct btrfs_delayed_ref_head *head);

	struct btrfs_delayed_ref_head *btrfs_select_ref_head(
	const struct btrfs_fs_info *fs_info,
	struct btrfs_delayed_ref_root *delayed_refs);
	void btrfs_unselect_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
	struct btrfs_delayed_ref_head *head);

	int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info, u64 seq);

	void btrfs_delayed_refs_rsv_release(struct btrfs_fs_info *fs_info, int nr_refs, int nr_csums);
	void btrfs_update_delayed_refs_rsv(struct btrfs_trans_handle *trans);
	void btrfs_inc_delayed_refs_rsv_bg_inserts(struct btrfs_fs_info *fs_info);
	void btrfs_dec_delayed_refs_rsv_bg_inserts(struct btrfs_fs_info *fs_info);
	void btrfs_inc_delayed_refs_rsv_bg_updates(struct btrfs_fs_info *fs_info);
	void btrfs_dec_delayed_refs_rsv_bg_updates(struct btrfs_fs_info *fs_info);
	int btrfs_delayed_refs_rsv_refill(struct btrfs_fs_info *fs_info,
	enum btrfs_reserve_flush_enum flush);
	bool btrfs_check_space_for_delayed_refs(struct btrfs_fs_info *fs_info);
	bool btrfs_find_delayed_tree_ref(struct btrfs_delayed_ref_head *head,
	u64 root, u64 parent);
	void btrfs_destroy_delayed_refs(struct btrfs_transaction *trans);

	static inline u64 btrfs_delayed_ref_owner(struct btrfs_delayed_ref_node *node)
	{
	if (node->type == BTRFS_EXTENT_DATA_REF_KEY \|\|
	node->type == BTRFS_SHARED_DATA_REF_KEY)
	return node->data_ref.objectid;
	return node->tree_ref.level;
	}

	static inline u64 btrfs_delayed_ref_offset(struct btrfs_delayed_ref_node *node)
	{
	if (node->type == BTRFS_EXTENT_DATA_REF_KEY \|\|
	node->type == BTRFS_SHARED_DATA_REF_KEY)
	return node->data_ref.offset;
	return 0;
	}

	static inline u8 btrfs_ref_type(struct btrfs_ref *ref)
	{
	ASSERT(ref->type == BTRFS_REF_DATA \|\| ref->type == BTRFS_REF_METADATA);

	if (ref->type == BTRFS_REF_DATA) {
	if (ref->parent)
	return BTRFS_SHARED_DATA_REF_KEY;
	else
	return BTRFS_EXTENT_DATA_REF_KEY;
	} else {
	if (ref->parent)
	return BTRFS_SHARED_BLOCK_REF_KEY;
	else
	return BTRFS_TREE_BLOCK_REF_KEY;
	}

	return 0;
	}

	#endif