LXR linux/fs/btrfs/delayed-ref.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2/*
   3 * Copyright (C) 2008 Oracle.  All rights reserved.
   4 */
   5
   6#ifndef BTRFS_DELAYED_REF_H
   7#define BTRFS_DELAYED_REF_H
   8
   9#include <linux/refcount.h>
  10
  11/* these are the possible values of struct btrfs_delayed_ref_node->action */
  12#define BTRFS_ADD_DELAYED_REF    1 /* add one backref to the tree */
  13#define BTRFS_DROP_DELAYED_REF   2 /* delete one backref from the tree */
  14#define BTRFS_ADD_DELAYED_EXTENT 3 /* record a full extent allocation */
  15#define BTRFS_UPDATE_DELAYED_HEAD 4 /* not changing ref count on head ref */
  16
  17struct btrfs_delayed_ref_node {
  18        struct rb_node ref_node;
  19        /*
  20         * If action is BTRFS_ADD_DELAYED_REF, also link this node to
  21         * ref_head->ref_add_list, then we do not need to iterate the
  22         * whole ref_head->ref_list to find BTRFS_ADD_DELAYED_REF nodes.
  23         */
  24        struct list_head add_list;
  25
  26        /* the starting bytenr of the extent */
  27        u64 bytenr;
  28
  29        /* the size of the extent */
  30        u64 num_bytes;
  31
  32        /* seq number to keep track of insertion order */
  33        u64 seq;
  34
  35        /* ref count on this data structure */
  36        refcount_t refs;
  37
  38        /*
  39         * how many refs is this entry adding or deleting.  For
  40         * head refs, this may be a negative number because it is keeping
  41         * track of the total mods done to the reference count.
  42         * For individual refs, this will always be a positive number
  43         *
  44         * It may be more than one, since it is possible for a single
  45         * parent to have more than one ref on an extent
  46         */
  47        int ref_mod;
  48
  49        unsigned int action:8;
  50        unsigned int type:8;
  51        /* is this node still in the rbtree? */
  52        unsigned int is_head:1;
  53        unsigned int in_tree:1;
  54};
  55
  56struct btrfs_delayed_extent_op {
  57        struct btrfs_disk_key key;
  58        u8 level;
  59        bool update_key;
  60        bool update_flags;
  61        bool is_data;
  62        u64 flags_to_set;
  63};
  64
  65/*
  66 * the head refs are used to hold a lock on a given extent, which allows us
  67 * to make sure that only one process is running the delayed refs
  68 * at a time for a single extent.  They also store the sum of all the
  69 * reference count modifications we've queued up.
  70 */
  71struct btrfs_delayed_ref_head {
  72        u64 bytenr;
  73        u64 num_bytes;
  74        refcount_t refs;
  75        /*
  76         * the mutex is held while running the refs, and it is also
  77         * held when checking the sum of reference modifications.
  78         */
  79        struct mutex mutex;
  80
  81        spinlock_t lock;
  82        struct rb_root_cached ref_tree;
  83        /* accumulate add BTRFS_ADD_DELAYED_REF nodes to this ref_add_list. */
  84        struct list_head ref_add_list;
  85
  86        struct rb_node href_node;
  87
  88        struct btrfs_delayed_extent_op *extent_op;
  89
  90        /*
  91         * This is used to track the final ref_mod from all the refs associated
  92         * with this head ref, this is not adjusted as delayed refs are run,
  93         * this is meant to track if we need to do the csum accounting or not.
  94         */
  95        int total_ref_mod;
  96
  97        /*
  98         * This is the current outstanding mod references for this bytenr.  This
  99         * is used with lookup_extent_info to get an accurate reference count
 100         * for a bytenr, so it is adjusted as delayed refs are run so that any
 101         * on disk reference count + ref_mod is accurate.
 102         */
 103        int ref_mod;
 104
 105        /*
 106         * For qgroup reserved space freeing.
 107         *
 108         * ref_root and reserved will be recorded after
 109         * BTRFS_ADD_DELAYED_EXTENT is called.
 110         * And will be used to free reserved qgroup space at
 111         * run_delayed_refs() time.
 112         */
 113        u64 qgroup_ref_root;
 114        u64 qgroup_reserved;
 115
 116        /*
 117         * when a new extent is allocated, it is just reserved in memory
 118         * The actual extent isn't inserted into the extent allocation tree
 119         * until the delayed ref is processed.  must_insert_reserved is
 120         * used to flag a delayed ref so the accounting can be updated
 121         * when a full insert is done.
 122         *
 123         * It is possible the extent will be freed before it is ever
 124         * inserted into the extent allocation tree.  In this case
 125         * we need to update the in ram accounting to properly reflect
 126         * the free has happened.
 127         */
 128        unsigned int must_insert_reserved:1;
 129        unsigned int is_data:1;
 130        unsigned int is_system:1;
 131        unsigned int processing:1;
 132};
 133
 134struct btrfs_delayed_tree_ref {
 135        struct btrfs_delayed_ref_node node;
 136        u64 root;
 137        u64 parent;
 138        int level;
 139};
 140
 141struct btrfs_delayed_data_ref {
 142        struct btrfs_delayed_ref_node node;
 143        u64 root;
 144        u64 parent;
 145        u64 objectid;
 146        u64 offset;
 147};
 148
 149struct btrfs_delayed_ref_root {
 150        /* head ref rbtree */
 151        struct rb_root_cached href_root;
 152
 153        /* dirty extent records */
 154        struct rb_root dirty_extent_root;
 155
 156        /* this spin lock protects the rbtree and the entries inside */
 157        spinlock_t lock;
 158
 159        /* how many delayed ref updates we've queued, used by the
 160         * throttling code
 161         */
 162        atomic_t num_entries;
 163
 164        /* total number of head nodes in tree */
 165        unsigned long num_heads;
 166
 167        /* total number of head nodes ready for processing */
 168        unsigned long num_heads_ready;
 169
 170        u64 pending_csums;
 171
 172        /*
 173         * set when the tree is flushing before a transaction commit,
 174         * used by the throttling code to decide if new updates need
 175         * to be run right away
 176         */
 177        int flushing;
 178
 179        u64 run_delayed_start;
 180
 181        /*
 182         * To make qgroup to skip given root.
 183         * This is for snapshot, as btrfs_qgroup_inherit() will manually
 184         * modify counters for snapshot and its source, so we should skip
 185         * the snapshot in new_root/old_roots or it will get calculated twice
 186         */
 187        u64 qgroup_to_skip;
 188};
 189
 190extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
 191extern struct kmem_cache *btrfs_delayed_tree_ref_cachep;
 192extern struct kmem_cache *btrfs_delayed_data_ref_cachep;
 193extern struct kmem_cache *btrfs_delayed_extent_op_cachep;
 194
 195int __init btrfs_delayed_ref_init(void);
 196void __cold btrfs_delayed_ref_exit(void);
 197
 198static inline struct btrfs_delayed_extent_op *
 199btrfs_alloc_delayed_extent_op(void)
 200{
 201        return kmem_cache_alloc(btrfs_delayed_extent_op_cachep, GFP_NOFS);
 202}
 203
 204static inline void
 205btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op *op)
 206{
 207        if (op)
 208                kmem_cache_free(btrfs_delayed_extent_op_cachep, op);
 209}
 210
 211static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
 212{
 213        WARN_ON(refcount_read(&ref->refs) == 0);
 214        if (refcount_dec_and_test(&ref->refs)) {
 215                WARN_ON(ref->in_tree);
 216                switch (ref->type) {
 217                case BTRFS_TREE_BLOCK_REF_KEY:
 218                case BTRFS_SHARED_BLOCK_REF_KEY:
 219                        kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
 220                        break;
 221                case BTRFS_EXTENT_DATA_REF_KEY:
 222                case BTRFS_SHARED_DATA_REF_KEY:
 223                        kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
 224                        break;
 225                default:
 226                        BUG();
 227                }
 228        }
 229}
 230
 231static inline void btrfs_put_delayed_ref_head(struct btrfs_delayed_ref_head *head)
 232{
 233        if (refcount_dec_and_test(&head->refs))
 234                kmem_cache_free(btrfs_delayed_ref_head_cachep, head);
 235}
 236
 237int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
 238                               u64 bytenr, u64 num_bytes, u64 parent,
 239                               u64 ref_root, int level, int action,
 240                               struct btrfs_delayed_extent_op *extent_op,
 241                               int *old_ref_mod, int *new_ref_mod);
 242int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
 243                               u64 bytenr, u64 num_bytes,
 244                               u64 parent, u64 ref_root,
 245                               u64 owner, u64 offset, u64 reserved, int action,
 246                               int *old_ref_mod, int *new_ref_mod);
 247int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
 248                                struct btrfs_trans_handle *trans,
 249                                u64 bytenr, u64 num_bytes,
 250                                struct btrfs_delayed_extent_op *extent_op);
 251void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
 252                              struct btrfs_delayed_ref_root *delayed_refs,
 253                              struct btrfs_delayed_ref_head *head);
 254
 255struct btrfs_delayed_ref_head *
 256btrfs_find_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
 257                            u64 bytenr);
 258int btrfs_delayed_ref_lock(struct btrfs_delayed_ref_root *delayed_refs,
 259                           struct btrfs_delayed_ref_head *head);
 260static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
 261{
 262        mutex_unlock(&head->mutex);
 263}
 264void btrfs_delete_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
 265                           struct btrfs_delayed_ref_head *head);
 266
 267struct btrfs_delayed_ref_head *btrfs_select_ref_head(
 268                struct btrfs_delayed_ref_root *delayed_refs);
 269
 270int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info, u64 seq);
 271
 272/*
 273 * helper functions to cast a node into its container
 274 */
 275static inline struct btrfs_delayed_tree_ref *
 276btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node)
 277{
 278        return container_of(node, struct btrfs_delayed_tree_ref, node);
 279}
 280
 281static inline struct btrfs_delayed_data_ref *
 282btrfs_delayed_node_to_data_ref(struct btrfs_delayed_ref_node *node)
 283{
 284        return container_of(node, struct btrfs_delayed_data_ref, node);
 285}
 286
 287#endif
 288