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![Josef Bacik](/assets/img/avatar_default.png)
As we delete large extents, we end up doing huge amounts of COW in order to delete the corresponding crcs. This adds accounting so that we keep track of that space and flushing of delayed refs so that we don't build up too much delayed crc work. This helps limit the delayed work that must be done at commit time and tries to avoid ENOSPC aborts because the crcs eat all the global reserves. Signed-off-by: Chris Mason <clm@fb.com>
276 lines
8 KiB
C
276 lines
8 KiB
C
/*
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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_node->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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#define BTRFS_UPDATE_DELAYED_HEAD 4 /* not changing ref count on head ref */
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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 size of the extent */
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u64 num_bytes;
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/* seq number to keep track of insertion order */
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u64 seq;
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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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unsigned int action:8;
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unsigned int type:8;
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unsigned int no_quota:1;
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/* is this node still in the rbtree? */
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unsigned int is_head:1;
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unsigned int in_tree:1;
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};
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struct btrfs_delayed_extent_op {
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struct btrfs_disk_key key;
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u64 flags_to_set;
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int level;
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unsigned int update_key:1;
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unsigned int update_flags:1;
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unsigned int is_data: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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spinlock_t lock;
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struct rb_root ref_root;
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struct rb_node href_node;
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struct btrfs_delayed_extent_op *extent_op;
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/*
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* This is used to track the final ref_mod from all the refs associated
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* with this head ref, this is not adjusted as delayed refs are run,
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* this is meant to track if we need to do the csum accounting or not.
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*/
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int total_ref_mod;
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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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unsigned int is_data:1;
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unsigned int processing:1;
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};
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struct btrfs_delayed_tree_ref {
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struct btrfs_delayed_ref_node node;
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u64 root;
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u64 parent;
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int level;
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};
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struct btrfs_delayed_data_ref {
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struct btrfs_delayed_ref_node node;
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u64 root;
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u64 parent;
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u64 objectid;
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u64 offset;
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};
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struct btrfs_delayed_ref_root {
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/* head ref rbtree */
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struct rb_root href_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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atomic_t num_entries;
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/* total number of head nodes in tree */
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unsigned long num_heads;
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/* total number of head nodes ready for processing */
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unsigned long num_heads_ready;
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u64 pending_csums;
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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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u64 run_delayed_start;
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};
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extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
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extern struct kmem_cache *btrfs_delayed_tree_ref_cachep;
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extern struct kmem_cache *btrfs_delayed_data_ref_cachep;
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extern struct kmem_cache *btrfs_delayed_extent_op_cachep;
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int btrfs_delayed_ref_init(void);
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void btrfs_delayed_ref_exit(void);
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static inline struct btrfs_delayed_extent_op *
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btrfs_alloc_delayed_extent_op(void)
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{
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return kmem_cache_alloc(btrfs_delayed_extent_op_cachep, GFP_NOFS);
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}
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static inline void
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btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op *op)
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{
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if (op)
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kmem_cache_free(btrfs_delayed_extent_op_cachep, op);
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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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switch (ref->type) {
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case BTRFS_TREE_BLOCK_REF_KEY:
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case BTRFS_SHARED_BLOCK_REF_KEY:
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kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
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break;
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case BTRFS_EXTENT_DATA_REF_KEY:
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case BTRFS_SHARED_DATA_REF_KEY:
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kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
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break;
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case 0:
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kmem_cache_free(btrfs_delayed_ref_head_cachep, ref);
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break;
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default:
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BUG();
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}
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}
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}
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int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
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struct btrfs_trans_handle *trans,
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u64 bytenr, u64 num_bytes, u64 parent,
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u64 ref_root, int level, int action,
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struct btrfs_delayed_extent_op *extent_op,
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int no_quota);
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int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
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struct btrfs_trans_handle *trans,
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u64 bytenr, u64 num_bytes,
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u64 parent, u64 ref_root,
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u64 owner, u64 offset, int action,
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struct btrfs_delayed_extent_op *extent_op,
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int no_quota);
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int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
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struct btrfs_trans_handle *trans,
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u64 bytenr, u64 num_bytes,
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struct btrfs_delayed_extent_op *extent_op);
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void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
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struct btrfs_fs_info *fs_info,
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struct btrfs_delayed_ref_root *delayed_refs,
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struct btrfs_delayed_ref_head *head);
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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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int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
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struct btrfs_delayed_ref_head *head);
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static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
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{
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mutex_unlock(&head->mutex);
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}
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struct btrfs_delayed_ref_head *
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btrfs_select_ref_head(struct btrfs_trans_handle *trans);
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int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info,
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struct btrfs_delayed_ref_root *delayed_refs,
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u64 seq);
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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->is_head;
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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_tree_ref *
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btrfs_delayed_node_to_tree_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_tree_ref, node);
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}
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static inline struct btrfs_delayed_data_ref *
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btrfs_delayed_node_to_data_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_data_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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