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

 /*
  * 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
	/*
	* 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