1 files changed, 459 insertions, 0 deletions
diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h
new file mode 100644
index 000000000..5ce940532
--- /dev/null
+++ b/fs/btrfs/delayed-ref.h
@@ -0,0 +1,459 @@
+/* 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/types.h>
+#include <linux/refcount.h>
+#include <linux/list.h>
+#include <linux/rbtree.h>
+#include <linux/mutex.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <uapi/linux/btrfs_tree.h>
+#include "fs.h"
+#include "messages.h"
+
+struct btrfs_trans_handle;
+struct btrfs_fs_info;
+
+/* these are the possible values of struct btrfs_delayed_ref_node->action */
+enum btrfs_delayed_ref_action {
+	/* Add one backref to the tree */
+	BTRFS_ADD_DELAYED_REF = 1,
+	/* Delete one backref from the tree */
+	BTRFS_DROP_DELAYED_REF,
+	/* Record a full extent allocation */
+	BTRFS_ADD_DELAYED_EXTENT,
+	/* Not changing ref count on head ref */
+	BTRFS_UPDATE_DELAYED_HEAD,
+} __packed;
+
+struct btrfs_data_ref {
+	/* For EXTENT_DATA_REF */
+
+	/* Inode which refers to this data extent */
+	u64 objectid;
+
+	/*
+	 * file_offset - extent_offset
+	 *
+	 * file_offset is the key.offset of the EXTENT_DATA key.
+	 * extent_offset is btrfs_file_extent_offset() of the EXTENT_DATA data.
+	 */
+	u64 offset;
+};
+
+struct btrfs_tree_ref {
+	/*
+	 * Level of this tree block.
+	 *
+	 * Shared for skinny (TREE_BLOCK_REF) and normal tree ref.
+	 */
+	int level;
+
+	/* For non-skinny metadata, no special member needed */
+};
+
+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
+	 * refs rbtree in the corresponding delayed ref head
+	 * (struct btrfs_delayed_ref_head::ref_tree).
+	 */
+	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;
+
+	/* The ref_root for this ref */
+	u64 ref_root;
+
+	/*
+	 * The parent for this ref, if this isn't set the ref_root is the
+	 * reference owner.
+	 */
+	u64 parent;
+
+	/* 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;
+
+	union {
+		struct btrfs_tree_ref tree_ref;
+		struct btrfs_data_ref data_ref;
+	};
+};
+
+struct btrfs_delayed_extent_op {
+	struct btrfs_disk_key key;
+	bool update_key;
+	bool update_flags;
+	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;
+	/*
+	 * the mutex is held while running the refs, and it is also
+	 * held when checking the sum of reference modifications.
+	 */
+	struct mutex mutex;
+
+	refcount_t refs;
+
+	/* Protects 'ref_tree' and 'ref_add_list'. */
+	spinlock_t lock;
+	struct rb_root_cached ref_tree;
+	/* accumulate add BTRFS_ADD_DELAYED_REF nodes to this ref_add_list. */
+	struct list_head ref_add_list;
+
+	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;
+
+	/*
+	 * The root that triggered the allocation when must_insert_reserved is
+	 * set to true.
+	 */
+	u64 owning_root;
+
+	/*
+	 * Track reserved bytes when setting must_insert_reserved.  On success
+	 * or cleanup, we will need to free the reservation.
+	 */
+	u64 reserved_bytes;
+
+	/* Tree block level, for metadata only. */
+	u8 level;
+
+	/*
+	 * 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.
+	 */
+	bool must_insert_reserved;
+
+	bool is_data;
+	bool is_system;
+	bool processing;
+	/*
+	 * Indicate if it's currently in the data structure that tracks head
+	 * refs (struct btrfs_delayed_ref_root::head_refs).
+	 */
+	bool tracked;
+};
+
+enum btrfs_delayed_ref_flags {
+	/* Indicate that we are flushing delayed refs for the commit */
+	BTRFS_DELAYED_REFS_FLUSHING,
+};
+
+struct btrfs_delayed_ref_root {
+	/*
+	 * Track head references.
+	 * The keys correspond to the logical address of the extent ("bytenr")
+	 * right shifted by fs_info->sectorsize_bits. This is both to get a more
+	 * dense index space (optimizes xarray structure) and because indexes in
+	 * xarrays are of "unsigned long" type, meaning they are 32 bits wide on
+	 * 32 bits platforms, limiting the extent range to 4G which is too low
+	 * and makes it unusable (truncated index values) on 32 bits platforms.
+	 * Protected by the spinlock 'lock' defined below.
+	 */
+	struct xarray head_refs;
+
+	/*
+	 * Track dirty extent records.
+	 * The keys correspond to the logical address of the extent ("bytenr")
+	 * right shifted by fs_info->sectorsize_bits, for same reasons as above.
+	 */
+	struct xarray dirty_extents;
+
+	/*
+	 * Protects the xarray head_refs, its entries and the following fields:
+	 * num_heads, num_heads_ready, pending_csums and run_delayed_start.
+	 */
+	spinlock_t lock;
+
+	/* Total number of head refs, protected by the spinlock 'lock'. */
+	unsigned long num_heads;
+
+	/*
+	 * Total number of head refs ready for processing, protected by the
+	 * spinlock 'lock'.
+	 */
+	unsigned long num_heads_ready;
+
+	/*
+	 * Track space reserved for deleting csums of data extents.
+	 * Protected by the spinlock 'lock'.
+	 */
+	u64 pending_csums;
+
+	unsigned long flags;
+
+	/*
+	 * Track from which bytenr to start searching ref heads.
+	 * Protected by the spinlock 'lock'.
+	 */
+	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;
+};
+
+enum btrfs_ref_type {
+	BTRFS_REF_NOT_SET,
+	BTRFS_REF_DATA,
+	BTRFS_REF_METADATA,
+} __packed;
+
+struct btrfs_ref {
+	enum btrfs_ref_type type;
+	enum btrfs_delayed_ref_action action;
+
+	/*
+	 * Whether this extent should go through qgroup record.
+	 *
+	 * Normally false, but for certain cases like delayed subtree scan,
+	 * setting this flag can hugely reduce qgroup overhead.
+	 */
+	bool skip_qgroup;
+
+	u64 bytenr;
+	u64 num_bytes;
+	u64 owning_root;
+
+	/*
+	 * The root that owns the reference for this reference, this will be set
+	 * or ->parent will be set, depending on what type of reference this is.
+	 */
+	u64 ref_root;
+
+	/* Bytenr of the parent tree block */
+	u64 parent;
+	union {
+		struct btrfs_data_ref data_ref;
+		struct btrfs_tree_ref tree_ref;
+	};
+
+#ifdef CONFIG_BTRFS_DEBUG
+	/* Through which root is this modification. */
+	u64 real_root;
+#endif
+};
+
+extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
+extern struct kmem_cache *btrfs_delayed_ref_node_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 u64 btrfs_calc_delayed_ref_bytes(const struct btrfs_fs_info *fs_info,
+					       int num_delayed_refs)
+{
+	u64 num_bytes;
+
+	num_bytes = btrfs_calc_insert_metadata_size(fs_info, num_delayed_refs);
+
+	/*
+	 * We have to check the mount option here because we could be enabling
+	 * the free space tree for the first time and don't have the compat_ro
+	 * option set yet.
+	 *
+	 * We need extra reservations if we have the free space tree because
+	 * we'll have to modify that tree as well.
+	 */
+	if (btrfs_test_opt(fs_info, FREE_SPACE_TREE))
+		num_bytes *= 2;
+
+	return num_bytes;
+}
+
+static inline u64 btrfs_calc_delayed_ref_csum_bytes(const struct btrfs_fs_info *fs_info,
+						    int num_csum_items)
+{
+	/*
+	 * Deleting csum items does not result in new nodes/leaves and does not
+	 * require changing the free space tree, only the csum tree, so this is
+	 * all we need.
+	 */
+	return btrfs_calc_metadata_size(fs_info, num_csum_items);
+}
+
+void btrfs_init_tree_ref(struct btrfs_ref *generic_ref, int level, u64 mod_root,
+			 bool skip_qgroup);
+void btrfs_init_data_ref(struct btrfs_ref *generic_ref, u64 ino, u64 offset,
+			 u64 mod_root, bool skip_qgroup);
+
+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);
+}
+
+void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref);
+
+static inline u64 btrfs_ref_head_to_space_flags(
+				struct btrfs_delayed_ref_head *head_ref)
+{
+	if (head_ref->is_data)
+		return BTRFS_BLOCK_GROUP_DATA;
+	else if (head_ref->is_system)
+		return BTRFS_BLOCK_GROUP_SYSTEM;
+	return BTRFS_BLOCK_GROUP_METADATA;
+}
+
+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,
+			       struct btrfs_ref *generic_ref,
+			       struct btrfs_delayed_extent_op *extent_op);
+int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
+			       struct btrfs_ref *generic_ref,
+			       u64 reserved);
+int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans,
+				u64 bytenr, u64 num_bytes, u8 level,
+				struct btrfs_delayed_extent_op *extent_op);
+void btrfs_merge_delayed_refs(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(const struct btrfs_fs_info *fs_info,
+			    struct btrfs_delayed_ref_root *delayed_refs,
+			    u64 bytenr);
+static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
+{
+	mutex_unlock(&head->mutex);
+}
+void btrfs_delete_ref_head(const 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_select_ref_head(
+		const struct btrfs_fs_info *fs_info,
+		struct btrfs_delayed_ref_root *delayed_refs);
+void btrfs_unselect_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
+			     struct btrfs_delayed_ref_head *head);
+struct btrfs_delayed_ref_node *btrfs_select_delayed_ref(struct btrfs_delayed_ref_head *head);
+
+int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info, u64 seq);
+
+void btrfs_delayed_refs_rsv_release(struct btrfs_fs_info *fs_info, int nr_refs, int nr_csums);
+void btrfs_update_delayed_refs_rsv(struct btrfs_trans_handle *trans);
+void btrfs_inc_delayed_refs_rsv_bg_inserts(struct btrfs_fs_info *fs_info);
+void btrfs_dec_delayed_refs_rsv_bg_inserts(struct btrfs_fs_info *fs_info);
+void btrfs_inc_delayed_refs_rsv_bg_updates(struct btrfs_fs_info *fs_info);
+void btrfs_dec_delayed_refs_rsv_bg_updates(struct btrfs_fs_info *fs_info);
+int btrfs_delayed_refs_rsv_refill(struct btrfs_fs_info *fs_info,
+				  enum btrfs_reserve_flush_enum flush);
+bool btrfs_check_space_for_delayed_refs(struct btrfs_fs_info *fs_info);
+bool btrfs_find_delayed_tree_ref(struct btrfs_delayed_ref_head *head,
+				 u64 root, u64 parent);
+void btrfs_destroy_delayed_refs(struct btrfs_transaction *trans);
+
+static inline u64 btrfs_delayed_ref_owner(const struct btrfs_delayed_ref_node *node)
+{
+	if (node->type == BTRFS_EXTENT_DATA_REF_KEY ||
+	    node->type == BTRFS_SHARED_DATA_REF_KEY)
+		return node->data_ref.objectid;
+	return node->tree_ref.level;
+}
+
+static inline u64 btrfs_delayed_ref_offset(const struct btrfs_delayed_ref_node *node)
+{
+	if (node->type == BTRFS_EXTENT_DATA_REF_KEY ||
+	    node->type == BTRFS_SHARED_DATA_REF_KEY)
+		return node->data_ref.offset;
+	return 0;
+}
+
+static inline u8 btrfs_ref_type(const struct btrfs_ref *ref)
+{
+	ASSERT(ref->type == BTRFS_REF_DATA || ref->type == BTRFS_REF_METADATA);
+
+	if (ref->type == BTRFS_REF_DATA) {
+		if (ref->parent)
+			return BTRFS_SHARED_DATA_REF_KEY;
+		else
+			return BTRFS_EXTENT_DATA_REF_KEY;
+	} else {
+		if (ref->parent)
+			return BTRFS_SHARED_BLOCK_REF_KEY;
+		else
+			return BTRFS_TREE_BLOCK_REF_KEY;
+	}
+
+	return 0;
+}
+
+#endif