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diff --git a/fs/btrfs/qgroup.h b/fs/btrfs/qgroup.h
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+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2014 Facebook. All rights reserved.
+ */
+
+#ifndef BTRFS_QGROUP_H
+#define BTRFS_QGROUP_H
+
+#include <linux/spinlock.h>
+#include <linux/rbtree.h>
+#include <linux/kobject.h>
+#include "ulist.h"
+#include "delayed-ref.h"
+#include "misc.h"
+
+/*
+ * Btrfs qgroup overview
+ *
+ * Btrfs qgroup splits into 3 main part:
+ * 1) Reserve
+ * Reserve metadata/data space for incoming operations
+ * Affect how qgroup limit works
+ *
+ * 2) Trace
+ * Tell btrfs qgroup to trace dirty extents.
+ *
+ * Dirty extents including:
+ * - Newly allocated extents
+ * - Extents going to be deleted (in this trans)
+ * - Extents whose owner is going to be modified
+ *
+ * This is the main part affects whether qgroup numbers will stay
+ * consistent.
+ * Btrfs qgroup can trace clean extents and won't cause any problem,
+ * but it will consume extra CPU time, it should be avoided if possible.
+ *
+ * 3) Account
+ * Btrfs qgroup will updates its numbers, based on dirty extents traced
+ * in previous step.
+ *
+ * Normally at qgroup rescan and transaction commit time.
+ */
+
+/*
+ * Special performance optimization for balance.
+ *
+ * For balance, we need to swap subtree of subvolume and reloc trees.
+ * In theory, we need to trace all subtree blocks of both subvolume and reloc
+ * trees, since their owner has changed during such swap.
+ *
+ * However since balance has ensured that both subtrees are containing the
+ * same contents and have the same tree structures, such swap won't cause
+ * qgroup number change.
+ *
+ * But there is a race window between subtree swap and transaction commit,
+ * during that window, if we increase/decrease tree level or merge/split tree
+ * blocks, we still need to trace the original subtrees.
+ *
+ * So for balance, we use a delayed subtree tracing, whose workflow is:
+ *
+ * 1) Record the subtree root block get swapped.
+ *
+ * During subtree swap:
+ * O = Old tree blocks
+ * N = New tree blocks
+ * reloc tree subvolume tree X
+ * Root Root
+ * / \ / \
+ * NA OB OA OB
+ * / | | \ / | | \
+ * NC ND OE OF OC OD OE OF
+ *
+ * In this case, NA and OA are going to be swapped, record (NA, OA) into
+ * subvolume tree X.
+ *
+ * 2) After subtree swap.
+ * reloc tree subvolume tree X
+ * Root Root
+ * / \ / \
+ * OA OB NA OB
+ * / | | \ / | | \
+ * OC OD OE OF NC ND OE OF
+ *
+ * 3a) COW happens for OB
+ * If we are going to COW tree block OB, we check OB's bytenr against
+ * tree X's swapped_blocks structure.
+ * If it doesn't fit any, nothing will happen.
+ *
+ * 3b) COW happens for NA
+ * Check NA's bytenr against tree X's swapped_blocks, and get a hit.
+ * Then we do subtree scan on both subtrees OA and NA.
+ * Resulting 6 tree blocks to be scanned (OA, OC, OD, NA, NC, ND).
+ *
+ * Then no matter what we do to subvolume tree X, qgroup numbers will
+ * still be correct.
+ * Then NA's record gets removed from X's swapped_blocks.
+ *
+ * 4) Transaction commit
+ * Any record in X's swapped_blocks gets removed, since there is no
+ * modification to the swapped subtrees, no need to trigger heavy qgroup
+ * subtree rescan for them.
+ */
+
+#define BTRFS_QGROUP_RUNTIME_FLAG_CANCEL_RESCAN (1UL << 3)
+#define BTRFS_QGROUP_RUNTIME_FLAG_NO_ACCOUNTING (1UL << 4)
+
+/*
+ * Record a dirty extent, and info qgroup to update quota on it
+ * TODO: Use kmem cache to alloc it.
+ */
+struct btrfs_qgroup_extent_record {
+ struct rb_node node;
+ u64 bytenr;
+ u64 num_bytes;
+
+ /*
+ * For qgroup reserved data space freeing.
+ *
+ * @data_rsv_refroot and @data_rsv will be recorded after
+ * BTRFS_ADD_DELAYED_EXTENT is called.
+ * And will be used to free reserved qgroup space at
+ * transaction commit time.
+ */
+ u32 data_rsv; /* reserved data space needs to be freed */
+ u64 data_rsv_refroot; /* which root the reserved data belongs to */
+ struct ulist *old_roots;
+};
+
+struct btrfs_qgroup_swapped_block {
+ struct rb_node node;
+
+ int level;
+ bool trace_leaf;
+
+ /* bytenr/generation of the tree block in subvolume tree after swap */
+ u64 subvol_bytenr;
+ u64 subvol_generation;
+
+ /* bytenr/generation of the tree block in reloc tree after swap */
+ u64 reloc_bytenr;
+ u64 reloc_generation;
+
+ u64 last_snapshot;
+ struct btrfs_key first_key;
+};
+
+/*
+ * Qgroup reservation types:
+ *
+ * DATA:
+ * space reserved for data
+ *
+ * META_PERTRANS:
+ * Space reserved for metadata (per-transaction)
+ * Due to the fact that qgroup data is only updated at transaction commit
+ * time, reserved space for metadata must be kept until transaction
+ * commits.
+ * Any metadata reserved that are used in btrfs_start_transaction() should
+ * be of this type.
+ *
+ * META_PREALLOC:
+ * There are cases where metadata space is reserved before starting
+ * transaction, and then btrfs_join_transaction() to get a trans handle.
+ * Any metadata reserved for such usage should be of this type.
+ * And after join_transaction() part (or all) of such reservation should
+ * be converted into META_PERTRANS.
+ */
+enum btrfs_qgroup_rsv_type {
+ BTRFS_QGROUP_RSV_DATA,
+ BTRFS_QGROUP_RSV_META_PERTRANS,
+ BTRFS_QGROUP_RSV_META_PREALLOC,
+ BTRFS_QGROUP_RSV_LAST,
+};
+
+/*
+ * Represents how many bytes we have reserved for this qgroup.
+ *
+ * Each type should have different reservation behavior.
+ * E.g, data follows its io_tree flag modification, while
+ * *currently* meta is just reserve-and-clear during transaction.
+ *
+ * TODO: Add new type for reservation which can survive transaction commit.
+ * Current metadata reservation behavior is not suitable for such case.
+ */
+struct btrfs_qgroup_rsv {
+ u64 values[BTRFS_QGROUP_RSV_LAST];
+};
+
+/*
+ * one struct for each qgroup, organized in fs_info->qgroup_tree.
+ */
+struct btrfs_qgroup {
+ u64 qgroupid;
+
+ /*
+ * state
+ */
+ u64 rfer; /* referenced */
+ u64 rfer_cmpr; /* referenced compressed */
+ u64 excl; /* exclusive */
+ u64 excl_cmpr; /* exclusive compressed */
+
+ /*
+ * limits
+ */
+ u64 lim_flags; /* which limits are set */
+ u64 max_rfer;
+ u64 max_excl;
+ u64 rsv_rfer;
+ u64 rsv_excl;
+
+ /*
+ * reservation tracking
+ */
+ struct btrfs_qgroup_rsv rsv;
+
+ /*
+ * lists
+ */
+ struct list_head groups; /* groups this group is member of */
+ struct list_head members; /* groups that are members of this group */
+ struct list_head dirty; /* dirty groups */
+
+ /*
+ * For qgroup iteration usage.
+ *
+ * The iteration list should always be empty until qgroup_iterator_add()
+ * is called. And should be reset to empty after the iteration is
+ * finished.
+ */
+ struct list_head iterator;
+ struct rb_node node; /* tree of qgroups */
+
+ /*
+ * temp variables for accounting operations
+ * Refer to qgroup_shared_accounting() for details.
+ */
+ u64 old_refcnt;
+ u64 new_refcnt;
+
+ /*
+ * Sysfs kobjectid
+ */
+ struct kobject kobj;
+};
+
+static inline u64 btrfs_qgroup_subvolid(u64 qgroupid)
+{
+ return (qgroupid & ((1ULL << BTRFS_QGROUP_LEVEL_SHIFT) - 1));
+}
+
+/*
+ * For qgroup event trace points only
+ */
+enum {
+ ENUM_BIT(QGROUP_RESERVE),
+ ENUM_BIT(QGROUP_RELEASE),
+ ENUM_BIT(QGROUP_FREE),
+};
+
+int btrfs_quota_enable(struct btrfs_fs_info *fs_info);
+int btrfs_quota_disable(struct btrfs_fs_info *fs_info);
+int btrfs_qgroup_rescan(struct btrfs_fs_info *fs_info);
+void btrfs_qgroup_rescan_resume(struct btrfs_fs_info *fs_info);
+int btrfs_qgroup_wait_for_completion(struct btrfs_fs_info *fs_info,
+ bool interruptible);
+int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans, u64 src,
+ u64 dst);
+int btrfs_del_qgroup_relation(struct btrfs_trans_handle *trans, u64 src,
+ u64 dst);
+int btrfs_create_qgroup(struct btrfs_trans_handle *trans, u64 qgroupid);
+int btrfs_remove_qgroup(struct btrfs_trans_handle *trans, u64 qgroupid);
+int btrfs_limit_qgroup(struct btrfs_trans_handle *trans, u64 qgroupid,
+ struct btrfs_qgroup_limit *limit);
+int btrfs_read_qgroup_config(struct btrfs_fs_info *fs_info);
+void btrfs_free_qgroup_config(struct btrfs_fs_info *fs_info);
+struct btrfs_delayed_extent_op;
+
+/*
+ * Inform qgroup to trace one dirty extent, its info is recorded in @record.
+ * So qgroup can account it at transaction committing time.
+ *
+ * No lock version, caller must acquire delayed ref lock and allocated memory,
+ * then call btrfs_qgroup_trace_extent_post() after exiting lock context.
+ *
+ * Return 0 for success insert
+ * Return >0 for existing record, caller can free @record safely.
+ * Error is not possible
+ */
+int btrfs_qgroup_trace_extent_nolock(
+ struct btrfs_fs_info *fs_info,
+ struct btrfs_delayed_ref_root *delayed_refs,
+ struct btrfs_qgroup_extent_record *record);
+
+/*
+ * Post handler after qgroup_trace_extent_nolock().
+ *
+ * NOTE: Current qgroup does the expensive backref walk at transaction
+ * committing time with TRANS_STATE_COMMIT_DOING, this blocks incoming
+ * new transaction.
+ * This is designed to allow btrfs_find_all_roots() to get correct new_roots
+ * result.
+ *
+ * However for old_roots there is no need to do backref walk at that time,
+ * since we search commit roots to walk backref and result will always be
+ * correct.
+ *
+ * Due to the nature of no lock version, we can't do backref there.
+ * So we must call btrfs_qgroup_trace_extent_post() after exiting
+ * spinlock context.
+ *
+ * TODO: If we can fix and prove btrfs_find_all_roots() can get correct result
+ * using current root, then we can move all expensive backref walk out of
+ * transaction committing, but not now as qgroup accounting will be wrong again.
+ */
+int btrfs_qgroup_trace_extent_post(struct btrfs_trans_handle *trans,
+ struct btrfs_qgroup_extent_record *qrecord);
+
+/*
+ * Inform qgroup to trace one dirty extent, specified by @bytenr and
+ * @num_bytes.
+ * So qgroup can account it at commit trans time.
+ *
+ * Better encapsulated version, with memory allocation and backref walk for
+ * commit roots.
+ * So this can sleep.
+ *
+ * Return 0 if the operation is done.
+ * Return <0 for error, like memory allocation failure or invalid parameter
+ * (NULL trans)
+ */
+int btrfs_qgroup_trace_extent(struct btrfs_trans_handle *trans, u64 bytenr,
+ u64 num_bytes);
+
+/*
+ * Inform qgroup to trace all leaf items of data
+ *
+ * Return 0 for success
+ * Return <0 for error(ENOMEM)
+ */
+int btrfs_qgroup_trace_leaf_items(struct btrfs_trans_handle *trans,
+ struct extent_buffer *eb);
+/*
+ * Inform qgroup to trace a whole subtree, including all its child tree
+ * blocks and data.
+ * The root tree block is specified by @root_eb.
+ *
+ * Normally used by relocation(tree block swap) and subvolume deletion.
+ *
+ * Return 0 for success
+ * Return <0 for error(ENOMEM or tree search error)
+ */
+int btrfs_qgroup_trace_subtree(struct btrfs_trans_handle *trans,
+ struct extent_buffer *root_eb,
+ u64 root_gen, int root_level);
+int btrfs_qgroup_account_extent(struct btrfs_trans_handle *trans, u64 bytenr,
+ u64 num_bytes, struct ulist *old_roots,
+ struct ulist *new_roots);
+int btrfs_qgroup_account_extents(struct btrfs_trans_handle *trans);
+int btrfs_run_qgroups(struct btrfs_trans_handle *trans);
+int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, u64 srcid,
+ u64 objectid, struct btrfs_qgroup_inherit *inherit);
+void btrfs_qgroup_free_refroot(struct btrfs_fs_info *fs_info,
+ u64 ref_root, u64 num_bytes,
+ enum btrfs_qgroup_rsv_type type);
+
+#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
+int btrfs_verify_qgroup_counts(struct btrfs_fs_info *fs_info, u64 qgroupid,
+ u64 rfer, u64 excl);
+#endif
+
+/* New io_tree based accurate qgroup reserve API */
+int btrfs_qgroup_reserve_data(struct btrfs_inode *inode,
+ struct extent_changeset **reserved, u64 start, u64 len);
+int btrfs_qgroup_release_data(struct btrfs_inode *inode, u64 start, u64 len, u64 *released);
+int btrfs_qgroup_free_data(struct btrfs_inode *inode,
+ struct extent_changeset *reserved, u64 start,
+ u64 len, u64 *freed);
+int btrfs_qgroup_reserve_meta(struct btrfs_root *root, int num_bytes,
+ enum btrfs_qgroup_rsv_type type, bool enforce);
+int __btrfs_qgroup_reserve_meta(struct btrfs_root *root, int num_bytes,
+ enum btrfs_qgroup_rsv_type type, bool enforce,
+ bool noflush);
+/* Reserve metadata space for pertrans and prealloc type */
+static inline int btrfs_qgroup_reserve_meta_pertrans(struct btrfs_root *root,
+ int num_bytes, bool enforce)
+{
+ return __btrfs_qgroup_reserve_meta(root, num_bytes,
+ BTRFS_QGROUP_RSV_META_PERTRANS,
+ enforce, false);
+}
+static inline int btrfs_qgroup_reserve_meta_prealloc(struct btrfs_root *root,
+ int num_bytes, bool enforce,
+ bool noflush)
+{
+ return __btrfs_qgroup_reserve_meta(root, num_bytes,
+ BTRFS_QGROUP_RSV_META_PREALLOC,
+ enforce, noflush);
+}
+
+void __btrfs_qgroup_free_meta(struct btrfs_root *root, int num_bytes,
+ enum btrfs_qgroup_rsv_type type);
+
+/* Free per-transaction meta reservation for error handling */
+static inline void btrfs_qgroup_free_meta_pertrans(struct btrfs_root *root,
+ int num_bytes)
+{
+ __btrfs_qgroup_free_meta(root, num_bytes,
+ BTRFS_QGROUP_RSV_META_PERTRANS);
+}
+
+/* Pre-allocated meta reservation can be freed at need */
+static inline void btrfs_qgroup_free_meta_prealloc(struct btrfs_root *root,
+ int num_bytes)
+{
+ __btrfs_qgroup_free_meta(root, num_bytes,
+ BTRFS_QGROUP_RSV_META_PREALLOC);
+}
+
+/*
+ * Per-transaction meta reservation should be all freed at transaction commit
+ * time
+ */
+void btrfs_qgroup_free_meta_all_pertrans(struct btrfs_root *root);
+
+/*
+ * Convert @num_bytes of META_PREALLOCATED reservation to META_PERTRANS.
+ *
+ * This is called when preallocated meta reservation needs to be used.
+ * Normally after btrfs_join_transaction() call.
+ */
+void btrfs_qgroup_convert_reserved_meta(struct btrfs_root *root, int num_bytes);
+
+void btrfs_qgroup_check_reserved_leak(struct btrfs_inode *inode);
+
+/* btrfs_qgroup_swapped_blocks related functions */
+void btrfs_qgroup_init_swapped_blocks(
+ struct btrfs_qgroup_swapped_blocks *swapped_blocks);
+
+void btrfs_qgroup_clean_swapped_blocks(struct btrfs_root *root);
+int btrfs_qgroup_add_swapped_blocks(struct btrfs_trans_handle *trans,
+ struct btrfs_root *subvol_root,
+ struct btrfs_block_group *bg,
+ struct extent_buffer *subvol_parent, int subvol_slot,
+ struct extent_buffer *reloc_parent, int reloc_slot,
+ u64 last_snapshot);
+int btrfs_qgroup_trace_subtree_after_cow(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root, struct extent_buffer *eb);
+void btrfs_qgroup_destroy_extent_records(struct btrfs_transaction *trans);
+bool btrfs_check_quota_leak(struct btrfs_fs_info *fs_info);
+
+#endif
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