2009-03-13 15:10:06 +01:00
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/*
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* Copyright (C) 2008 Oracle. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#ifndef __DELAYED_REF__
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#define __DELAYED_REF__
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/* these are the possible values of struct btrfs_delayed_ref->action */
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#define BTRFS_ADD_DELAYED_REF 1 /* add one backref to the tree */
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#define BTRFS_DROP_DELAYED_REF 2 /* delete one backref from the tree */
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#define BTRFS_ADD_DELAYED_EXTENT 3 /* record a full extent allocation */
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struct btrfs_delayed_ref_node {
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struct rb_node rb_node;
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/* the starting bytenr of the extent */
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u64 bytenr;
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/* the parent our backref will point to */
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u64 parent;
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/* the size of the extent */
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u64 num_bytes;
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/* ref count on this data structure */
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atomic_t refs;
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/*
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* how many refs is this entry adding or deleting. For
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* head refs, this may be a negative number because it is keeping
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* track of the total mods done to the reference count.
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* For individual refs, this will always be a positive number
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*
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* It may be more than one, since it is possible for a single
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* parent to have more than one ref on an extent
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*/
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int ref_mod;
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/* is this node still in the rbtree? */
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unsigned int in_tree:1;
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};
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/*
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* the head refs are used to hold a lock on a given extent, which allows us
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* to make sure that only one process is running the delayed refs
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* at a time for a single extent. They also store the sum of all the
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* reference count modifications we've queued up.
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*/
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struct btrfs_delayed_ref_head {
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struct btrfs_delayed_ref_node node;
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/*
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* the mutex is held while running the refs, and it is also
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* held when checking the sum of reference modifications.
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*/
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struct mutex mutex;
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/*
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* when a new extent is allocated, it is just reserved in memory
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* The actual extent isn't inserted into the extent allocation tree
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* until the delayed ref is processed. must_insert_reserved is
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* used to flag a delayed ref so the accounting can be updated
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* when a full insert is done.
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*
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* It is possible the extent will be freed before it is ever
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* inserted into the extent allocation tree. In this case
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* we need to update the in ram accounting to properly reflect
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* the free has happened.
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*/
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unsigned int must_insert_reserved:1;
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};
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struct btrfs_delayed_ref {
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struct btrfs_delayed_ref_node node;
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/* the root objectid our ref will point to */
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u64 root;
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/* the generation for the backref */
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u64 generation;
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/* owner_objectid of the backref */
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u64 owner_objectid;
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/* operation done by this entry in the rbtree */
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u8 action;
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/* if pin == 1, when the extent is freed it will be pinned until
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* transaction commit
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*/
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unsigned int pin:1;
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};
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struct btrfs_delayed_ref_root {
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struct rb_root root;
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/* this spin lock protects the rbtree and the entries inside */
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spinlock_t lock;
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/* how many delayed ref updates we've queued, used by the
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* throttling code
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*/
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unsigned long num_entries;
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/*
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* set when the tree is flushing before a transaction commit,
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* used by the throttling code to decide if new updates need
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* to be run right away
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*/
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int flushing;
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};
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static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
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{
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WARN_ON(atomic_read(&ref->refs) == 0);
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if (atomic_dec_and_test(&ref->refs)) {
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WARN_ON(ref->in_tree);
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kfree(ref);
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}
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}
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int btrfs_add_delayed_ref(struct btrfs_trans_handle *trans,
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u64 bytenr, u64 num_bytes, u64 parent, u64 ref_root,
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u64 ref_generation, u64 owner_objectid, int action,
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int pin);
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2009-03-13 15:11:24 +01:00
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struct btrfs_delayed_ref_head *
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btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr);
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2009-03-13 15:10:06 +01:00
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int btrfs_delayed_ref_pending(struct btrfs_trans_handle *trans, u64 bytenr);
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int btrfs_lock_delayed_ref(struct btrfs_trans_handle *trans,
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struct btrfs_delayed_ref_node *ref,
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struct btrfs_delayed_ref_head **next_ret);
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int btrfs_lookup_extent_ref(struct btrfs_trans_handle *trans,
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struct btrfs_root *root, u64 bytenr,
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u64 num_bytes, u32 *refs);
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int btrfs_update_delayed_ref(struct btrfs_trans_handle *trans,
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u64 bytenr, u64 num_bytes, u64 orig_parent,
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u64 parent, u64 orig_ref_root, u64 ref_root,
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u64 orig_ref_generation, u64 ref_generation,
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u64 owner_objectid, int pin);
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/*
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* a node might live in a head or a regular ref, this lets you
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* test for the proper type to use.
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*/
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static int btrfs_delayed_ref_is_head(struct btrfs_delayed_ref_node *node)
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{
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return node->parent == (u64)-1;
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}
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/*
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* helper functions to cast a node into its container
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*/
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static inline struct btrfs_delayed_ref *
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btrfs_delayed_node_to_ref(struct btrfs_delayed_ref_node *node)
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{
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WARN_ON(btrfs_delayed_ref_is_head(node));
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return container_of(node, struct btrfs_delayed_ref, node);
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}
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static inline struct btrfs_delayed_ref_head *
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btrfs_delayed_node_to_head(struct btrfs_delayed_ref_node *node)
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{
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WARN_ON(!btrfs_delayed_ref_is_head(node));
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return container_of(node, struct btrfs_delayed_ref_head, node);
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}
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#endif
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