v4.19.13 snapshot.
diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h
new file mode 100644
index 0000000..d9f2a4e
--- /dev/null
+++ b/fs/btrfs/delayed-ref.h
@@ -0,0 +1,286 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2008 Oracle. All rights reserved.
+ */
+
+#ifndef BTRFS_DELAYED_REF_H
+#define BTRFS_DELAYED_REF_H
+
+#include <linux/refcount.h>
+
+/* 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 ref_node;
+ /*
+ * If action is BTRFS_ADD_DELAYED_REF, also link this node to
+ * ref_head->ref_add_list, then we do not need to iterate the
+ * whole ref_head->ref_list to find BTRFS_ADD_DELAYED_REF nodes.
+ */
+ struct list_head add_list;
+
+ /* 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 */
+ refcount_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;
+ u8 level;
+ bool update_key;
+ bool update_flags;
+ bool is_data;
+ u64 flags_to_set;
+};
+
+/*
+ * 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 {
+ u64 bytenr;
+ u64 num_bytes;
+ refcount_t refs;
+ /*
+ * 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_tree;
+ /* accumulate add BTRFS_ADD_DELAYED_REF nodes to this ref_add_list. */
+ struct list_head ref_add_list;
+
+ struct rb_node href_node;
+
+ struct btrfs_delayed_extent_op *extent_op;
+
+ /*
+ * This is used to track the final ref_mod from all the refs associated
+ * with this head ref, this is not adjusted as delayed refs are run,
+ * this is meant to track if we need to do the csum accounting or not.
+ */
+ int total_ref_mod;
+
+ /*
+ * This is the current outstanding mod references for this bytenr. This
+ * is used with lookup_extent_info to get an accurate reference count
+ * for a bytenr, so it is adjusted as delayed refs are run so that any
+ * on disk reference count + ref_mod is accurate.
+ */
+ int ref_mod;
+
+ /*
+ * For qgroup reserved space freeing.
+ *
+ * ref_root and reserved will be recorded after
+ * BTRFS_ADD_DELAYED_EXTENT is called.
+ * And will be used to free reserved qgroup space at
+ * run_delayed_refs() time.
+ */
+ u64 qgroup_ref_root;
+ u64 qgroup_reserved;
+
+ /*
+ * 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 is_system: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;
+
+ /* dirty extent records */
+ struct rb_root dirty_extent_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;
+
+ u64 pending_csums;
+
+ /*
+ * 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;
+
+ /*
+ * To make qgroup to skip given root.
+ * This is for snapshot, as btrfs_qgroup_inherit() will manually
+ * modify counters for snapshot and its source, so we should skip
+ * the snapshot in new_root/old_roots or it will get calculated twice
+ */
+ u64 qgroup_to_skip;
+};
+
+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 __init btrfs_delayed_ref_init(void);
+void __cold 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(refcount_read(&ref->refs) == 0);
+ if (refcount_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;
+ default:
+ BUG();
+ }
+ }
+}
+
+static inline void btrfs_put_delayed_ref_head(struct btrfs_delayed_ref_head *head)
+{
+ if (refcount_dec_and_test(&head->refs))
+ kmem_cache_free(btrfs_delayed_ref_head_cachep, head);
+}
+
+int btrfs_add_delayed_tree_ref(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 *old_ref_mod, int *new_ref_mod);
+int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
+ u64 bytenr, u64 num_bytes,
+ u64 parent, u64 ref_root,
+ u64 owner, u64 offset, u64 reserved, int action,
+ int *old_ref_mod, int *new_ref_mod);
+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_delayed_ref_root *delayed_refs,
+ struct btrfs_delayed_ref_head *head);
+
+struct btrfs_delayed_ref_head *
+btrfs_find_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
+ 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, u64 seq);
+
+/*
+ * 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)
+{
+ 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)
+{
+ return container_of(node, struct btrfs_delayed_data_ref, node);
+}
+
+#endif