- 根目录:
- fs
- btrfs
- delayed-ref.h
/*
* 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