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/types.h>
  10 #include <linux/refcount.h>
  11 #include <linux/list.h>
  12 #include <linux/rbtree.h>
  13 #include <linux/mutex.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/slab.h>
  16 #include <uapi/linux/btrfs_tree.h>
  17
  18 struct btrfs_trans_handle;
  19 struct btrfs_fs_info;
  20
  21 /* these are the possible values of struct btrfs_delayed_ref_node->action */
  22 enum btrfs_delayed_ref_action {
  23         /* Add one backref to the tree */
  24         BTRFS_ADD_DELAYED_REF = 1,
  25         /* Delete one backref from the tree */
  26         BTRFS_DROP_DELAYED_REF,
  27         /* Record a full extent allocation */
  28         BTRFS_ADD_DELAYED_EXTENT,
  29         /* Not changing ref count on head ref */
  30         BTRFS_UPDATE_DELAYED_HEAD,
  31 } __packed;
  32
  33 struct btrfs_data_ref {
  34         /* For EXTENT_DATA_REF */
  35
  36         /* Inode which refers to this data extent */
  37         u64 objectid;
  38
  39         /*
  40          * file_offset - extent_offset
  41          *
  42          * file_offset is the key.offset of the EXTENT_DATA key.
  43          * extent_offset is btrfs_file_extent_offset() of the EXTENT_DATA data.
  44          */
  45         u64 offset;
  46 };
  47
  48 struct btrfs_tree_ref {
  49         /*
  50          * Level of this tree block.
  51          *
  52          * Shared for skinny (TREE_BLOCK_REF) and normal tree ref.
  53          */
  54         int level;
  55
  56         /* For non-skinny metadata, no special member needed */
  57 };
  58
  59 struct btrfs_delayed_ref_node {
  60         struct rb_node ref_node;
  61         /*
  62          * If action is BTRFS_ADD_DELAYED_REF, also link this node to
  63          * ref_head->ref_add_list, then we do not need to iterate the
  64          * whole ref_head->ref_list to find BTRFS_ADD_DELAYED_REF nodes.
  65          */
  66         struct list_head add_list;
  67
  68         /* the starting bytenr of the extent */
  69         u64 bytenr;
  70
  71         /* the size of the extent */
  72         u64 num_bytes;
  73
  74         /* seq number to keep track of insertion order */
  75         u64 seq;
  76
  77         /* The ref_root for this ref */
  78         u64 ref_root;
  79
  80         /*
  81          * The parent for this ref, if this isn't set the ref_root is the
  82          * reference owner.
  83          */
  84         u64 parent;
  85
  86         /* ref count on this data structure */
  87         refcount_t refs;
  88
  89         /*
  90          * how many refs is this entry adding or deleting.  For
  91          * head refs, this may be a negative number because it is keeping
  92          * track of the total mods done to the reference count.
  93          * For individual refs, this will always be a positive number
  94          *
  95          * It may be more than one, since it is possible for a single
  96          * parent to have more than one ref on an extent
  97          */
  98         int ref_mod;
  99
 100         unsigned int action:8;
 101         unsigned int type:8;
 102
 103         union {
 104                 struct btrfs_tree_ref tree_ref;
 105                 struct btrfs_data_ref data_ref;
 106         };
 107 };
 108
 109 struct btrfs_delayed_extent_op {
 110         struct btrfs_disk_key key;
 111         bool update_key;
 112         bool update_flags;
 113         u64 flags_to_set;
 114 };
 115
 116 /*
 117  * the head refs are used to hold a lock on a given extent, which allows us
 118  * to make sure that only one process is running the delayed refs
 119  * at a time for a single extent.  They also store the sum of all the
 120  * reference count modifications we've queued up.
 121  */
 122 struct btrfs_delayed_ref_head {
 123         u64 bytenr;
 124         u64 num_bytes;
 125         /*
 126          * For insertion into struct btrfs_delayed_ref_root::href_root.
 127          * Keep it in the same cache line as 'bytenr' for more efficient
 128          * searches in the rbtree.
 129          */
 130         struct rb_node href_node;
 131         /*
 132          * the mutex is held while running the refs, and it is also
 133          * held when checking the sum of reference modifications.
 134          */
 135         struct mutex mutex;
 136
 137         refcount_t refs;
 138
 139         /* Protects 'ref_tree' and 'ref_add_list'. */
 140         spinlock_t lock;
 141         struct rb_root_cached ref_tree;
 142         /* accumulate add BTRFS_ADD_DELAYED_REF nodes to this ref_add_list. */
 143         struct list_head ref_add_list;
 144
 145         struct btrfs_delayed_extent_op *extent_op;
 146
 147         /*
 148          * This is used to track the final ref_mod from all the refs associated
 149          * with this head ref, this is not adjusted as delayed refs are run,
 150          * this is meant to track if we need to do the csum accounting or not.
 151          */
 152         int total_ref_mod;
 153
 154         /*
 155          * This is the current outstanding mod references for this bytenr.  This
 156          * is used with lookup_extent_info to get an accurate reference count
 157          * for a bytenr, so it is adjusted as delayed refs are run so that any
 158          * on disk reference count + ref_mod is accurate.
 159          */
 160         int ref_mod;
 161
 162         /*
 163          * The root that triggered the allocation when must_insert_reserved is
 164          * set to true.
 165          */
 166         u64 owning_root;
 167
 168         /*
 169          * Track reserved bytes when setting must_insert_reserved.  On success
 170          * or cleanup, we will need to free the reservation.
 171          */
 172         u64 reserved_bytes;
 173
 174         /* Tree block level, for metadata only. */
 175         u8 level;
 176
 177         /*
 178          * when a new extent is allocated, it is just reserved in memory
 179          * The actual extent isn't inserted into the extent allocation tree
 180          * until the delayed ref is processed.  must_insert_reserved is
 181          * used to flag a delayed ref so the accounting can be updated
 182          * when a full insert is done.
 183          *
 184          * It is possible the extent will be freed before it is ever
 185          * inserted into the extent allocation tree.  In this case
 186          * we need to update the in ram accounting to properly reflect
 187          * the free has happened.
 188          */
 189         bool must_insert_reserved;
 190
 191         bool is_data;
 192         bool is_system;
 193         bool processing;
 194 };
 195
 196 enum btrfs_delayed_ref_flags {
 197         /* Indicate that we are flushing delayed refs for the commit */
 198         BTRFS_DELAYED_REFS_FLUSHING,
 199 };
 200
 201 struct btrfs_delayed_ref_root {
 202         /* head ref rbtree */
 203         struct rb_root_cached href_root;
 204
 205         /* Track dirty extent records. */
 206         struct xarray dirty_extents;
 207
 208         /* this spin lock protects the rbtree and the entries inside */
 209         spinlock_t lock;
 210
 211         /* how many delayed ref updates we've queued, used by the
 212          * throttling code
 213          */
 214         atomic_t num_entries;
 215
 216         /* total number of head nodes in tree */
 217         unsigned long num_heads;
 218
 219         /* total number of head nodes ready for processing */
 220         unsigned long num_heads_ready;
 221
 222         u64 pending_csums;
 223
 224         unsigned long flags;
 225
 226         u64 run_delayed_start;
 227
 228         /*
 229          * To make qgroup to skip given root.
 230          * This is for snapshot, as btrfs_qgroup_inherit() will manually
 231          * modify counters for snapshot and its source, so we should skip
 232          * the snapshot in new_root/old_roots or it will get calculated twice
 233          */
 234         u64 qgroup_to_skip;
 235 };
 236
 237 enum btrfs_ref_type {
 238         BTRFS_REF_NOT_SET,
 239         BTRFS_REF_DATA,
 240         BTRFS_REF_METADATA,
 241         BTRFS_REF_LAST,
 242 } __packed;
 243
 244 struct btrfs_ref {
 245         enum btrfs_ref_type type;
 246         enum btrfs_delayed_ref_action action;
 247
 248         /*
 249          * Whether this extent should go through qgroup record.
 250          *
 251          * Normally false, but for certain cases like delayed subtree scan,
 252          * setting this flag can hugely reduce qgroup overhead.
 253          */
 254         bool skip_qgroup;
 255
 256 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
 257         /* Through which root is this modification. */
 258         u64 real_root;
 259 #endif
 260         u64 bytenr;
 261         u64 num_bytes;
 262         u64 owning_root;
 263
 264         /*
 265          * The root that owns the reference for this reference, this will be set
 266          * or ->parent will be set, depending on what type of reference this is.
 267          */
 268         u64 ref_root;
 269
 270         /* Bytenr of the parent tree block */
 271         u64 parent;
 272         union {
 273                 struct btrfs_data_ref data_ref;
 274                 struct btrfs_tree_ref tree_ref;
 275         };
 276 };
 277
 278 extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
 279 extern struct kmem_cache *btrfs_delayed_ref_node_cachep;
 280 extern struct kmem_cache *btrfs_delayed_extent_op_cachep;
 281
 282 int __init btrfs_delayed_ref_init(void);
 283 void __cold btrfs_delayed_ref_exit(void);
 284
 285 static inline u64 btrfs_calc_delayed_ref_bytes(const struct btrfs_fs_info *fs_info,
 286                                                int num_delayed_refs)
 287 {
 288         u64 num_bytes;
 289
 290         num_bytes = btrfs_calc_insert_metadata_size(fs_info, num_delayed_refs);
 291
 292         /*
 293          * We have to check the mount option here because we could be enabling
 294          * the free space tree for the first time and don't have the compat_ro
 295          * option set yet.
 296          *
 297          * We need extra reservations if we have the free space tree because
 298          * we'll have to modify that tree as well.
 299          */
 300         if (btrfs_test_opt(fs_info, FREE_SPACE_TREE))
 301                 num_bytes *= 2;
 302
 303         return num_bytes;
 304 }
 305
 306 static inline u64 btrfs_calc_delayed_ref_csum_bytes(const struct btrfs_fs_info *fs_info,
 307                                                     int num_csum_items)
 308 {
 309         /*
 310          * Deleting csum items does not result in new nodes/leaves and does not
 311          * require changing the free space tree, only the csum tree, so this is
 312          * all we need.
 313          */
 314         return btrfs_calc_metadata_size(fs_info, num_csum_items);
 315 }
 316
 317 void btrfs_init_tree_ref(struct btrfs_ref *generic_ref, int level, u64 mod_root,
 318                          bool skip_qgroup);
 319 void btrfs_init_data_ref(struct btrfs_ref *generic_ref, u64 ino, u64 offset,
 320                          u64 mod_root, bool skip_qgroup);
 321
 322 static inline struct btrfs_delayed_extent_op *
 323 btrfs_alloc_delayed_extent_op(void)
 324 {
 325         return kmem_cache_alloc(btrfs_delayed_extent_op_cachep, GFP_NOFS);
 326 }
 327
 328 static inline void
 329 btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op *op)
 330 {
 331         if (op)
 332                 kmem_cache_free(btrfs_delayed_extent_op_cachep, op);
 333 }
 334
 335 void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref);
 336
 337 static inline u64 btrfs_ref_head_to_space_flags(
 338                                 struct btrfs_delayed_ref_head *head_ref)
 339 {
 340         if (head_ref->is_data)
 341                 return BTRFS_BLOCK_GROUP_DATA;
 342         else if (head_ref->is_system)
 343                 return BTRFS_BLOCK_GROUP_SYSTEM;
 344         return BTRFS_BLOCK_GROUP_METADATA;
 345 }
 346
 347 static inline void btrfs_put_delayed_ref_head(struct btrfs_delayed_ref_head *head)
 348 {
 349         if (refcount_dec_and_test(&head->refs))
 350                 kmem_cache_free(btrfs_delayed_ref_head_cachep, head);
 351 }
 352
 353 int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
 354                                struct btrfs_ref *generic_ref,
 355                                struct btrfs_delayed_extent_op *extent_op);
 356 int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
 357                                struct btrfs_ref *generic_ref,
 358                                u64 reserved);
 359 int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans,
 360                                 u64 bytenr, u64 num_bytes, u8 level,
 361                                 struct btrfs_delayed_extent_op *extent_op);
 362 void btrfs_merge_delayed_refs(struct btrfs_fs_info *fs_info,
 363                               struct btrfs_delayed_ref_root *delayed_refs,
 364                               struct btrfs_delayed_ref_head *head);
 365
 366 struct btrfs_delayed_ref_head *
 367 btrfs_find_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
 368                             u64 bytenr);
 369 int btrfs_delayed_ref_lock(struct btrfs_delayed_ref_root *delayed_refs,
 370                            struct btrfs_delayed_ref_head *head);
 371 static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
 372 {
 373         mutex_unlock(&head->mutex);
 374 }
 375 void btrfs_delete_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
 376                            struct btrfs_delayed_ref_head *head);
 377
 378 struct btrfs_delayed_ref_head *btrfs_select_ref_head(
 379                 struct btrfs_delayed_ref_root *delayed_refs);
 380
 381 int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info, u64 seq);
 382
 383 void btrfs_delayed_refs_rsv_release(struct btrfs_fs_info *fs_info, int nr_refs, int nr_csums);
 384 void btrfs_update_delayed_refs_rsv(struct btrfs_trans_handle *trans);
 385 void btrfs_inc_delayed_refs_rsv_bg_inserts(struct btrfs_fs_info *fs_info);
 386 void btrfs_dec_delayed_refs_rsv_bg_inserts(struct btrfs_fs_info *fs_info);
 387 void btrfs_inc_delayed_refs_rsv_bg_updates(struct btrfs_fs_info *fs_info);
 388 void btrfs_dec_delayed_refs_rsv_bg_updates(struct btrfs_fs_info *fs_info);
 389 int btrfs_delayed_refs_rsv_refill(struct btrfs_fs_info *fs_info,
 390                                   enum btrfs_reserve_flush_enum flush);
 391 bool btrfs_check_space_for_delayed_refs(struct btrfs_fs_info *fs_info);
 392 bool btrfs_find_delayed_tree_ref(struct btrfs_delayed_ref_head *head,
 393                                  u64 root, u64 parent);
 394
 395 static inline u64 btrfs_delayed_ref_owner(struct btrfs_delayed_ref_node *node)
 396 {
 397         if (node->type == BTRFS_EXTENT_DATA_REF_KEY ||
 398             node->type == BTRFS_SHARED_DATA_REF_KEY)
 399                 return node->data_ref.objectid;
 400         return node->tree_ref.level;
 401 }
 402
 403 static inline u64 btrfs_delayed_ref_offset(struct btrfs_delayed_ref_node *node)
 404 {
 405         if (node->type == BTRFS_EXTENT_DATA_REF_KEY ||
 406             node->type == BTRFS_SHARED_DATA_REF_KEY)
 407                 return node->data_ref.offset;
 408         return 0;
 409 }
 410
 411 static inline u8 btrfs_ref_type(struct btrfs_ref *ref)
 412 {
 413         ASSERT(ref->type == BTRFS_REF_DATA || ref->type == BTRFS_REF_METADATA);
 414
 415         if (ref->type == BTRFS_REF_DATA) {
 416                 if (ref->parent)
 417                         return BTRFS_SHARED_DATA_REF_KEY;
 418                 else
 419                         return BTRFS_EXTENT_DATA_REF_KEY;
 420         } else {
 421                 if (ref->parent)
 422                         return BTRFS_SHARED_BLOCK_REF_KEY;
 423                 else
 424                         return BTRFS_TREE_BLOCK_REF_KEY;
 425         }
 426
 427         return 0;
 428 }
 429
 430 #endif