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Diffstat (limited to 'fs/btrfs/delayed-ref.h')
| -rw-r--r-- | fs/btrfs/delayed-ref.h | 283 |
1 files changed, 283 insertions, 0 deletions
diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h new file mode 100644 index 00000000..d8f244d9 --- /dev/null +++ b/fs/btrfs/delayed-ref.h @@ -0,0 +1,283 @@ +/* + * 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->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; + 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; + + struct list_head cluster; + + 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; +}; + +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 { + struct rb_root 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 + */ + unsigned long 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; + + /* + * seq number of delayed refs. We need to know if a backref was being + * added before the currently processed ref or afterwards. + */ + u64 seq; + + /* + * seq_list holds a list of all seq numbers that are currently being + * added to the list. While walking backrefs (btrfs_find_all_roots, + * qgroups), which might take some time, no newer ref must be processed, + * as it might influence the outcome of the walk. + */ + struct list_head seq_head; + + /* + * when the only refs we have in the list must not be processed, we want + * to wait for more refs to show up or for the end of backref walking. + */ + wait_queue_head_t seq_wait; +}; + +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); + kfree(ref); + } +} + +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); + +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); +int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans, + struct list_head *cluster, u64 search_start); + +struct seq_list { + struct list_head list; + u64 seq; +}; + +static inline u64 inc_delayed_seq(struct btrfs_delayed_ref_root *delayed_refs) +{ + assert_spin_locked(&delayed_refs->lock); + ++delayed_refs->seq; + return delayed_refs->seq; +} + +static inline void +btrfs_get_delayed_seq(struct btrfs_delayed_ref_root *delayed_refs, + struct seq_list *elem) +{ + assert_spin_locked(&delayed_refs->lock); + elem->seq = delayed_refs->seq; + list_add_tail(&elem->list, &delayed_refs->seq_head); +} + +static inline void +btrfs_put_delayed_seq(struct btrfs_delayed_ref_root *delayed_refs, + struct seq_list *elem) +{ + spin_lock(&delayed_refs->lock); + list_del(&elem->list); + wake_up(&delayed_refs->seq_wait); + spin_unlock(&delayed_refs->lock); +} + +int btrfs_check_delayed_seq(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 |