/*
   * Copyright (C) 2008 Oracle.  All rights reserved.
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public
   * License v2 as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   *
   * You should have received a copy of the GNU General Public
   * License along with this program; if not, write to the
   * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   * Boston, MA 021110-1307, USA.
   */
  #ifndef __DELAYED_REF__
  #define __DELAYED_REF__
  
  /* these are the possible values of struct btrfs_delayed_ref_node->action */
  #define BTRFS_ADD_DELAYED_REF    1 /* add one backref to the tree */
  #define BTRFS_DROP_DELAYED_REF   2 /* delete one backref from the tree */
  #define BTRFS_ADD_DELAYED_EXTENT 3 /* record a full extent allocation */
  #define BTRFS_UPDATE_DELAYED_HEAD 4 /* not changing ref count on head ref */
  
  struct btrfs_delayed_ref_node {
  	struct rb_node rb_node;
  
  	/* 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;
  
  	/* ref count on this data structure */
  	atomic_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;
  	/* is this node still in the rbtree? */
  	unsigned int is_head:1;
  	unsigned int in_tree:1;
  };
  
  struct btrfs_delayed_extent_op {
  	struct btrfs_disk_key key;
  	u64 flags_to_set;
  	int level;
  	unsigned int update_key:1;
  	unsigned int update_flags:1;
  	unsigned int is_data:1;
  };
  
  /*
   * 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 {
  	struct btrfs_delayed_ref_node node;
  
  	/*
  	 * the mutex is held while running the refs, and it is also
  	 * held when checking the sum of reference modifications.
  	 */
  	struct mutex mutex;
  
  	spinlock_t lock;
  	struct rb_root ref_root;
  
  	struct rb_node href_node;
  
  	struct btrfs_delayed_extent_op *extent_op;
  	/*
  	 * 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.
  	 */
  	unsigned int must_insert_reserved:1;
  	unsigned int is_data:1;
  	unsigned int processing:1;
  };
  
  struct btrfs_delayed_tree_ref {
  	struct btrfs_delayed_ref_node node;
  	u64 root;
  	u64 parent;
  	int level;
  };
  
  struct btrfs_delayed_data_ref {
  	struct btrfs_delayed_ref_node node;
  	u64 root;
  	u64 parent;
  	u64 objectid;
  	u64 offset;
  };
  
  struct btrfs_delayed_ref_root {
  	/* head ref rbtree */
  	struct rb_root href_root;
  
  	/* this spin lock protects the rbtree and the entries inside */
  	spinlock_t lock;
  
  	/* how many delayed ref updates we've queued, used by the
  	 * throttling code
  	 */
  	atomic_t num_entries;
  
  	/* total number of head nodes in tree */
  	unsigned long num_heads;
  
  	/* total number of head nodes ready for processing */
  	unsigned long num_heads_ready;
  
  	/*
  	 * set when the tree is flushing before a transaction commit,
  	 * used by the throttling code to decide if new updates need
  	 * to be run right away
  	 */
  	int flushing;
  
  	u64 run_delayed_start;
  };
  
  extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
  extern struct kmem_cache *btrfs_delayed_tree_ref_cachep;
  extern struct kmem_cache *btrfs_delayed_data_ref_cachep;
  extern struct kmem_cache *btrfs_delayed_extent_op_cachep;
  
  int btrfs_delayed_ref_init(void);
  void btrfs_delayed_ref_exit(void);
  
  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);
  }
  
  static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
  {
  	WARN_ON(atomic_read(&ref->refs) == 0);
  	if (atomic_dec_and_test(&ref->refs)) {
  		WARN_ON(ref->in_tree);
  		switch (ref->type) {
  		case BTRFS_TREE_BLOCK_REF_KEY:
  		case BTRFS_SHARED_BLOCK_REF_KEY:
  			kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
  			break;
  		case BTRFS_EXTENT_DATA_REF_KEY:
  		case BTRFS_SHARED_DATA_REF_KEY:
  			kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
  			break;
  		case 0:
  			kmem_cache_free(btrfs_delayed_ref_head_cachep, ref);
  			break;
  		default:
  			BUG();
  		}
  	}
  }
  
  int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
  			       struct btrfs_trans_handle *trans,
  			       u64 bytenr, u64 num_bytes, u64 parent,
  			       u64 ref_root, int level, int action,
  			       struct btrfs_delayed_extent_op *extent_op,
  			       int for_cow);
  int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
  			       struct btrfs_trans_handle *trans,
  			       u64 bytenr, u64 num_bytes,
  			       u64 parent, u64 ref_root,
  			       u64 owner, u64 offset, int action,
  			       struct btrfs_delayed_extent_op *extent_op,
  			       int for_cow);
  int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
  				struct btrfs_trans_handle *trans,
  				u64 bytenr, u64 num_bytes,
  				struct btrfs_delayed_extent_op *extent_op);
  void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
  			      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(struct btrfs_trans_handle *trans, u64 bytenr);
  int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
  			   struct btrfs_delayed_ref_head *head);
  static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
  {
  	mutex_unlock(&head->mutex);
  }
  
  
  struct btrfs_delayed_ref_head *
  btrfs_select_ref_head(struct btrfs_trans_handle *trans);
  
  int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info,
  			    struct btrfs_delayed_ref_root *delayed_refs,
  			    u64 seq);
  
  /*
   * delayed refs with a ref_seq > 0 must be held back during backref walking.
   * this only applies to items in one of the fs-trees. for_cow items never need
   * to be held back, so they won't get a ref_seq number.
   */
  static inline int need_ref_seq(int for_cow, u64 rootid)
  {
  	if (for_cow)
  		return 0;
  
  	if (rootid == BTRFS_FS_TREE_OBJECTID)
  		return 1;
  
  	if ((s64)rootid >= (s64)BTRFS_FIRST_FREE_OBJECTID)
  		return 1;
  
  	return 0;
  }
  
  /*
   * a node might live in a head or a regular ref, this lets you
   * test for the proper type to use.
   */
  static int btrfs_delayed_ref_is_head(struct btrfs_delayed_ref_node *node)
  {
  	return node->is_head;
  }
  
  /*
   * helper functions to cast a node into its container
   */
  static inline struct btrfs_delayed_tree_ref *
  btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node)
  {
  	WARN_ON(btrfs_delayed_ref_is_head(node));
  	return container_of(node, struct btrfs_delayed_tree_ref, node);
  }
  
  static inline struct btrfs_delayed_data_ref *
  btrfs_delayed_node_to_data_ref(struct btrfs_delayed_ref_node *node)
  {
  	WARN_ON(btrfs_delayed_ref_is_head(node));
  	return container_of(node, struct btrfs_delayed_data_ref, node);
  }
  
  static inline struct btrfs_delayed_ref_head *
  btrfs_delayed_node_to_head(struct btrfs_delayed_ref_node *node)
  {
  	WARN_ON(!btrfs_delayed_ref_is_head(node));
  	return container_of(node, struct btrfs_delayed_ref_head, node);
  }
  #endif