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
  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 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
 134 struct btrfs_delayed_tree_ref {
 135         struct btrfs_delayed_ref_node node;
 136         u64 root;
 137         u64 parent;
 138         int level;
 139 };
 140
 141 struct 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
 149 struct btrfs_delayed_ref_root {
 150         /* head ref rbtree */
 151         struct rb_root 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
 190 extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
 191 extern struct kmem_cache *btrfs_delayed_tree_ref_cachep;
 192 extern struct kmem_cache *btrfs_delayed_data_ref_cachep;
 193 extern struct kmem_cache *btrfs_delayed_extent_op_cachep;
 194
 195 int __init btrfs_delayed_ref_init(void);
 196 void __cold btrfs_delayed_ref_exit(void);
 197
 198 static inline struct btrfs_delayed_extent_op *
 199 btrfs_alloc_delayed_extent_op(void)
 200 {
 201         return kmem_cache_alloc(btrfs_delayed_extent_op_cachep, GFP_NOFS);
 202 }
 203
 204 static inline void
 205 btrfs_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
 211 static 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
 231 static 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
 237 int 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);
 242 int 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);
 247 int 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);
 251 void 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
 255 struct btrfs_delayed_ref_head *
 256 btrfs_find_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
 257                             u64 bytenr);
 258 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
 259                            struct btrfs_delayed_ref_head *head);
 260 static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
 261 {
 262         mutex_unlock(&head->mutex);
 263 }
 264
 265
 266 struct btrfs_delayed_ref_head *
 267 btrfs_select_ref_head(struct btrfs_trans_handle *trans);
 268
 269 int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info, u64 seq);
 270
 271 /*
 272  * helper functions to cast a node into its container
 273  */
 274 static inline struct btrfs_delayed_tree_ref *
 275 btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node)
 276 {
 277         return container_of(node, struct btrfs_delayed_tree_ref, node);
 278 }
 279
 280 static inline struct btrfs_delayed_data_ref *
 281 btrfs_delayed_node_to_data_ref(struct btrfs_delayed_ref_node *node)
 282 {
 283         return container_of(node, struct btrfs_delayed_data_ref, node);
 284 }
 285
 286 #endif