root/fs/btrfs/delayed-ref.h

INCLUDED FROM

DEFINITIONS

1. btrfs_init_generic_ref
2. btrfs_init_tree_ref
3. btrfs_init_data_ref
4. btrfs_alloc_delayed_extent_op
5. btrfs_free_delayed_extent_op
6. btrfs_put_delayed_ref
7. btrfs_put_delayed_ref_head
8. btrfs_delayed_ref_unlock
9. btrfs_delayed_node_to_tree_ref
10. btrfs_delayed_node_to_data_ref

   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 
  17 struct 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 
  56 struct 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  */
  71 struct 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          * when a new extent is allocated, it is just reserved in memory
 107          * The actual extent isn't inserted into the extent allocation tree
 108          * until the delayed ref is processed.  must_insert_reserved is
 109          * used to flag a delayed ref so the accounting can be updated
 110          * when a full insert is done.
 111          *
 112          * It is possible the extent will be freed before it is ever
 113          * inserted into the extent allocation tree.  In this case
 114          * we need to update the in ram accounting to properly reflect
 115          * the free has happened.
 116          */
 117         unsigned int must_insert_reserved:1;
 118         unsigned int is_data:1;
 119         unsigned int is_system:1;
 120         unsigned int processing:1;
 121 };
 122 
 123 struct btrfs_delayed_tree_ref {
 124         struct btrfs_delayed_ref_node node;
 125         u64 root;
 126         u64 parent;
 127         int level;
 128 };
 129 
 130 struct btrfs_delayed_data_ref {
 131         struct btrfs_delayed_ref_node node;
 132         u64 root;
 133         u64 parent;
 134         u64 objectid;
 135         u64 offset;
 136 };
 137 
 138 struct btrfs_delayed_ref_root {
 139         /* head ref rbtree */
 140         struct rb_root_cached href_root;
 141 
 142         /* dirty extent records */
 143         struct rb_root dirty_extent_root;
 144 
 145         /* this spin lock protects the rbtree and the entries inside */
 146         spinlock_t lock;
 147 
 148         /* how many delayed ref updates we've queued, used by the
 149          * throttling code
 150          */
 151         atomic_t num_entries;
 152 
 153         /* total number of head nodes in tree */
 154         unsigned long num_heads;
 155 
 156         /* total number of head nodes ready for processing */
 157         unsigned long num_heads_ready;
 158 
 159         u64 pending_csums;
 160 
 161         /*
 162          * set when the tree is flushing before a transaction commit,
 163          * used by the throttling code to decide if new updates need
 164          * to be run right away
 165          */
 166         int flushing;
 167 
 168         u64 run_delayed_start;
 169 
 170         /*
 171          * To make qgroup to skip given root.
 172          * This is for snapshot, as btrfs_qgroup_inherit() will manually
 173          * modify counters for snapshot and its source, so we should skip
 174          * the snapshot in new_root/old_roots or it will get calculated twice
 175          */
 176         u64 qgroup_to_skip;
 177 };
 178 
 179 enum btrfs_ref_type {
 180         BTRFS_REF_NOT_SET,
 181         BTRFS_REF_DATA,
 182         BTRFS_REF_METADATA,
 183         BTRFS_REF_LAST,
 184 };
 185 
 186 struct btrfs_data_ref {
 187         /* For EXTENT_DATA_REF */
 188 
 189         /* Root which refers to this data extent */
 190         u64 ref_root;
 191 
 192         /* Inode which refers to this data extent */
 193         u64 ino;
 194 
 195         /*
 196          * file_offset - extent_offset
 197          *
 198          * file_offset is the key.offset of the EXTENT_DATA key.
 199          * extent_offset is btrfs_file_extent_offset() of the EXTENT_DATA data.
 200          */
 201         u64 offset;
 202 };
 203 
 204 struct btrfs_tree_ref {
 205         /*
 206          * Level of this tree block
 207          *
 208          * Shared for skinny (TREE_BLOCK_REF) and normal tree ref.
 209          */
 210         int level;
 211 
 212         /*
 213          * Root which refers to this tree block.
 214          *
 215          * For TREE_BLOCK_REF (skinny metadata, either inline or keyed)
 216          */
 217         u64 root;
 218 
 219         /* For non-skinny metadata, no special member needed */
 220 };
 221 
 222 struct btrfs_ref {
 223         enum btrfs_ref_type type;
 224         int action;
 225 
 226         /*
 227          * Whether this extent should go through qgroup record.
 228          *
 229          * Normally false, but for certain cases like delayed subtree scan,
 230          * setting this flag can hugely reduce qgroup overhead.
 231          */
 232         bool skip_qgroup;
 233 
 234         /*
 235          * Optional. For which root is this modification.
 236          * Mostly used for qgroup optimization.
 237          *
 238          * When unset, data/tree ref init code will populate it.
 239          * In certain cases, we're modifying reference for a different root.
 240          * E.g. COW fs tree blocks for balance.
 241          * In that case, tree_ref::root will be fs tree, but we're doing this
 242          * for reloc tree, then we should set @real_root to reloc tree.
 243          */
 244         u64 real_root;
 245         u64 bytenr;
 246         u64 len;
 247 
 248         /* Bytenr of the parent tree block */
 249         u64 parent;
 250         union {
 251                 struct btrfs_data_ref data_ref;
 252                 struct btrfs_tree_ref tree_ref;
 253         };
 254 };
 255 
 256 extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
 257 extern struct kmem_cache *btrfs_delayed_tree_ref_cachep;
 258 extern struct kmem_cache *btrfs_delayed_data_ref_cachep;
 259 extern struct kmem_cache *btrfs_delayed_extent_op_cachep;
 260 
 261 int __init btrfs_delayed_ref_init(void);
 262 void __cold btrfs_delayed_ref_exit(void);
 263 
 264 static inline void btrfs_init_generic_ref(struct btrfs_ref *generic_ref,
 265                                 int action, u64 bytenr, u64 len, u64 parent)
 266 {
 267         generic_ref->action = action;
 268         generic_ref->bytenr = bytenr;
 269         generic_ref->len = len;
 270         generic_ref->parent = parent;
 271 }
 272 
 273 static inline void btrfs_init_tree_ref(struct btrfs_ref *generic_ref,
 274                                 int level, u64 root)
 275 {
 276         /* If @real_root not set, use @root as fallback */
 277         if (!generic_ref->real_root)
 278                 generic_ref->real_root = root;
 279         generic_ref->tree_ref.level = level;
 280         generic_ref->tree_ref.root = root;
 281         generic_ref->type = BTRFS_REF_METADATA;
 282 }
 283 
 284 static inline void btrfs_init_data_ref(struct btrfs_ref *generic_ref,
 285                                 u64 ref_root, u64 ino, u64 offset)
 286 {
 287         /* If @real_root not set, use @root as fallback */
 288         if (!generic_ref->real_root)
 289                 generic_ref->real_root = ref_root;
 290         generic_ref->data_ref.ref_root = ref_root;
 291         generic_ref->data_ref.ino = ino;
 292         generic_ref->data_ref.offset = offset;
 293         generic_ref->type = BTRFS_REF_DATA;
 294 }
 295 
 296 static inline struct btrfs_delayed_extent_op *
 297 btrfs_alloc_delayed_extent_op(void)
 298 {
 299         return kmem_cache_alloc(btrfs_delayed_extent_op_cachep, GFP_NOFS);
 300 }
 301 
 302 static inline void
 303 btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op *op)
 304 {
 305         if (op)
 306                 kmem_cache_free(btrfs_delayed_extent_op_cachep, op);
 307 }
 308 
 309 static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
 310 {
 311         WARN_ON(refcount_read(&ref->refs) == 0);
 312         if (refcount_dec_and_test(&ref->refs)) {
 313                 WARN_ON(ref->in_tree);
 314                 switch (ref->type) {
 315                 case BTRFS_TREE_BLOCK_REF_KEY:
 316                 case BTRFS_SHARED_BLOCK_REF_KEY:
 317                         kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
 318                         break;
 319                 case BTRFS_EXTENT_DATA_REF_KEY:
 320                 case BTRFS_SHARED_DATA_REF_KEY:
 321                         kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
 322                         break;
 323                 default:
 324                         BUG();
 325                 }
 326         }
 327 }
 328 
 329 static inline void btrfs_put_delayed_ref_head(struct btrfs_delayed_ref_head *head)
 330 {
 331         if (refcount_dec_and_test(&head->refs))
 332                 kmem_cache_free(btrfs_delayed_ref_head_cachep, head);
 333 }
 334 
 335 int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
 336                                struct btrfs_ref *generic_ref,
 337                                struct btrfs_delayed_extent_op *extent_op,
 338                                int *old_ref_mod, int *new_ref_mod);
 339 int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
 340                                struct btrfs_ref *generic_ref,
 341                                u64 reserved, int *old_ref_mod,
 342                                int *new_ref_mod);
 343 int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans,
 344                                 u64 bytenr, u64 num_bytes,
 345                                 struct btrfs_delayed_extent_op *extent_op);
 346 void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
 347                               struct btrfs_delayed_ref_root *delayed_refs,
 348                               struct btrfs_delayed_ref_head *head);
 349 
 350 struct btrfs_delayed_ref_head *
 351 btrfs_find_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
 352                             u64 bytenr);
 353 int btrfs_delayed_ref_lock(struct btrfs_delayed_ref_root *delayed_refs,
 354                            struct btrfs_delayed_ref_head *head);
 355 static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
 356 {
 357         mutex_unlock(&head->mutex);
 358 }
 359 void btrfs_delete_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
 360                            struct btrfs_delayed_ref_head *head);
 361 
 362 struct btrfs_delayed_ref_head *btrfs_select_ref_head(
 363                 struct btrfs_delayed_ref_root *delayed_refs);
 364 
 365 int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info, u64 seq);
 366 
 367 void btrfs_delayed_refs_rsv_release(struct btrfs_fs_info *fs_info, int nr);
 368 void btrfs_update_delayed_refs_rsv(struct btrfs_trans_handle *trans);
 369 int btrfs_delayed_refs_rsv_refill(struct btrfs_fs_info *fs_info,
 370                                   enum btrfs_reserve_flush_enum flush);
 371 void btrfs_migrate_to_delayed_refs_rsv(struct btrfs_fs_info *fs_info,
 372                                        struct btrfs_block_rsv *src,
 373                                        u64 num_bytes);
 374 int btrfs_should_throttle_delayed_refs(struct btrfs_trans_handle *trans);
 375 bool btrfs_check_space_for_delayed_refs(struct btrfs_fs_info *fs_info);
 376 
 377 /*
 378  * helper functions to cast a node into its container
 379  */
 380 static inline struct btrfs_delayed_tree_ref *
 381 btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node)
 382 {
 383         return container_of(node, struct btrfs_delayed_tree_ref, node);
 384 }
 385 
 386 static inline struct btrfs_delayed_data_ref *
 387 btrfs_delayed_node_to_data_ref(struct btrfs_delayed_ref_node *node)
 388 {
 389         return container_of(node, struct btrfs_delayed_data_ref, node);
 390 }
 391 
 392 #endif