fs/btrfs/delayed-ref.h

   1 /*
   2  * Copyright (C) 2008 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18 #ifndef __DELAYED_REF__
  19 #define __DELAYED_REF__
  20
  21 /* these are the possible values of struct btrfs_delayed_ref_node->action */
  22 #define BTRFS_ADD_DELAYED_REF    1 /* add one backref to the tree */
  23 #define BTRFS_DROP_DELAYED_REF   2 /* delete one backref from the tree */
  24 #define BTRFS_ADD_DELAYED_EXTENT 3 /* record a full extent allocation */
  25 #define BTRFS_UPDATE_DELAYED_HEAD 4 /* not changing ref count on head ref */
  26
  27 /*
  28  * XXX: Qu: I really hate the design that ref_head and tree/data ref shares the
  29  * same ref_node structure.
  30  * Ref_head is in a higher logic level than tree/data ref, and duplicated
  31  * bytenr/num_bytes in ref_node is really a waste or memory, they should be
  32  * referred from ref_head.
  33  * This gets more disgusting after we use list to store tree/data ref in
  34  * ref_head. Must clean this mess up later.
  35  */
  36 struct btrfs_delayed_ref_node {
  37         /*
  38          * ref_head use rb tree, stored in ref_root->href.
  39          * indexed by bytenr
  40          */
  41         struct rb_node rb_node;
  42
  43         /*data/tree ref use list, stored in ref_head->ref_list. */
  44         struct list_head list;
  45
  46         /* the starting bytenr of the extent */
  47         u64 bytenr;
  48
  49         /* the size of the extent */
  50         u64 num_bytes;
  51
  52         /* seq number to keep track of insertion order */
  53         u64 seq;
  54
  55         /* ref count on this data structure */
  56         atomic_t refs;
  57
  58         /*
  59          * how many refs is this entry adding or deleting.  For
  60          * head refs, this may be a negative number because it is keeping
  61          * track of the total mods done to the reference count.
  62          * For individual refs, this will always be a positive number
  63          *
  64          * It may be more than one, since it is possible for a single
  65          * parent to have more than one ref on an extent
  66          */
  67         int ref_mod;
  68
  69         unsigned int action:8;
  70         unsigned int type:8;
  71         unsigned int no_quota:1;
  72         /* is this node still in the rbtree? */
  73         unsigned int is_head:1;
  74         unsigned int in_tree:1;
  75 };
  76
  77 struct btrfs_delayed_extent_op {
  78         struct btrfs_disk_key key;
  79         u64 flags_to_set;
  80         int level;
  81         unsigned int update_key:1;
  82         unsigned int update_flags:1;
  83         unsigned int is_data:1;
  84 };
  85
  86 /*
  87  * the head refs are used to hold a lock on a given extent, which allows us
  88  * to make sure that only one process is running the delayed refs
  89  * at a time for a single extent.  They also store the sum of all the
  90  * reference count modifications we've queued up.
  91  */
  92 struct btrfs_delayed_ref_head {
  93         struct btrfs_delayed_ref_node node;
  94
  95         /*
  96          * the mutex is held while running the refs, and it is also
  97          * held when checking the sum of reference modifications.
  98          */
  99         struct mutex mutex;
 100
 101         spinlock_t lock;
 102         struct list_head ref_list;
 103
 104         struct rb_node href_node;
 105
 106         struct btrfs_delayed_extent_op *extent_op;
 107
 108         /*
 109          * This is used to track the final ref_mod from all the refs associated
 110          * with this head ref, this is not adjusted as delayed refs are run,
 111          * this is meant to track if we need to do the csum accounting or not.
 112          */
 113         int total_ref_mod;
 114
 115         /*
 116          * when a new extent is allocated, it is just reserved in memory
 117          * The actual extent isn't inserted into the extent allocation tree
 118          * until the delayed ref is processed.  must_insert_reserved is
 119          * used to flag a delayed ref so the accounting can be updated
 120          * when a full insert is done.
 121          *
 122          * It is possible the extent will be freed before it is ever
 123          * inserted into the extent allocation tree.  In this case
 124          * we need to update the in ram accounting to properly reflect
 125          * the free has happened.
 126          */
 127         unsigned int must_insert_reserved:1;
 128         unsigned int is_data:1;
 129         unsigned int processing:1;
 130 };
 131
 132 struct btrfs_delayed_tree_ref {
 133         struct btrfs_delayed_ref_node node;
 134         u64 root;
 135         u64 parent;
 136         int level;
 137 };
 138
 139 struct btrfs_delayed_data_ref {
 140         struct btrfs_delayed_ref_node node;
 141         u64 root;
 142         u64 parent;
 143         u64 objectid;
 144         u64 offset;
 145 };
 146
 147 struct btrfs_delayed_ref_root {
 148         /* head ref rbtree */
 149         struct rb_root href_root;
 150
 151         /* dirty extent records */
 152         struct rb_root dirty_extent_root;
 153
 154         /* this spin lock protects the rbtree and the entries inside */
 155         spinlock_t lock;
 156
 157         /* how many delayed ref updates we've queued, used by the
 158          * throttling code
 159          */
 160         atomic_t num_entries;
 161
 162         /* total number of head nodes in tree */
 163         unsigned long num_heads;
 164
 165         /* total number of head nodes ready for processing */
 166         unsigned long num_heads_ready;
 167
 168         u64 pending_csums;
 169
 170         /*
 171          * set when the tree is flushing before a transaction commit,
 172          * used by the throttling code to decide if new updates need
 173          * to be run right away
 174          */
 175         int flushing;
 176
 177         u64 run_delayed_start;
 178
 179         /*
 180          * To make qgroup to skip given root.
 181          * This is for snapshot, as btrfs_qgroup_inherit() will manully
 182          * modify counters for snapshot and its source, so we should skip
 183          * the snapshot in new_root/old_roots or it will get calculated twice
 184          */
 185         u64 qgroup_to_skip;
 186 };
 187
 188 extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
 189 extern struct kmem_cache *btrfs_delayed_tree_ref_cachep;
 190 extern struct kmem_cache *btrfs_delayed_data_ref_cachep;
 191 extern struct kmem_cache *btrfs_delayed_extent_op_cachep;
 192
 193 int btrfs_delayed_ref_init(void);
 194 void btrfs_delayed_ref_exit(void);
 195
 196 static inline struct btrfs_delayed_extent_op *
 197 btrfs_alloc_delayed_extent_op(void)
 198 {
 199         return kmem_cache_alloc(btrfs_delayed_extent_op_cachep, GFP_NOFS);
 200 }
 201
 202 static inline void
 203 btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op *op)
 204 {
 205         if (op)
 206                 kmem_cache_free(btrfs_delayed_extent_op_cachep, op);
 207 }
 208
 209 static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
 210 {
 211         WARN_ON(atomic_read(&ref->refs) == 0);
 212         if (atomic_dec_and_test(&ref->refs)) {
 213                 WARN_ON(ref->in_tree);
 214                 switch (ref->type) {
 215                 case BTRFS_TREE_BLOCK_REF_KEY:
 216                 case BTRFS_SHARED_BLOCK_REF_KEY:
 217                         kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
 218                         break;
 219                 case BTRFS_EXTENT_DATA_REF_KEY:
 220                 case BTRFS_SHARED_DATA_REF_KEY:
 221                         kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
 222                         break;
 223                 case 0:
 224                         kmem_cache_free(btrfs_delayed_ref_head_cachep, ref);
 225                         break;
 226                 default:
 227                         BUG();
 228                 }
 229         }
 230 }
 231
 232 int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
 233                                struct btrfs_trans_handle *trans,
 234                                u64 bytenr, u64 num_bytes, u64 parent,
 235                                u64 ref_root, int level, int action,
 236                                struct btrfs_delayed_extent_op *extent_op,
 237                                int no_quota);
 238 int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
 239                                struct btrfs_trans_handle *trans,
 240                                u64 bytenr, u64 num_bytes,
 241                                u64 parent, u64 ref_root,
 242                                u64 owner, u64 offset, int action,
 243                                struct btrfs_delayed_extent_op *extent_op,
 244                                int no_quota);
 245 int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
 246                                 struct btrfs_trans_handle *trans,
 247                                 u64 bytenr, u64 num_bytes,
 248                                 struct btrfs_delayed_extent_op *extent_op);
 249 void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
 250                               struct btrfs_fs_info *fs_info,
 251                               struct btrfs_delayed_ref_root *delayed_refs,
 252                               struct btrfs_delayed_ref_head *head);
 253
 254 struct btrfs_delayed_ref_head *
 255 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr);
 256 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
 257                            struct btrfs_delayed_ref_head *head);
 258 static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
 259 {
 260         mutex_unlock(&head->mutex);
 261 }
 262
 263
 264 struct btrfs_delayed_ref_head *
 265 btrfs_select_ref_head(struct btrfs_trans_handle *trans);
 266
 267 int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info,
 268                             struct btrfs_delayed_ref_root *delayed_refs,
 269                             u64 seq);
 270
 271 /*
 272  * a node might live in a head or a regular ref, this lets you
 273  * test for the proper type to use.
 274  */
 275 static int btrfs_delayed_ref_is_head(struct btrfs_delayed_ref_node *node)
 276 {
 277         return node->is_head;
 278 }
 279
 280 /*
 281  * helper functions to cast a node into its container
 282  */
 283 static inline struct btrfs_delayed_tree_ref *
 284 btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node)
 285 {
 286         WARN_ON(btrfs_delayed_ref_is_head(node));
 287         return container_of(node, struct btrfs_delayed_tree_ref, node);
 288 }
 289
 290 static inline struct btrfs_delayed_data_ref *
 291 btrfs_delayed_node_to_data_ref(struct btrfs_delayed_ref_node *node)
 292 {
 293         WARN_ON(btrfs_delayed_ref_is_head(node));
 294         return container_of(node, struct btrfs_delayed_data_ref, node);
 295 }
 296
 297 static inline struct btrfs_delayed_ref_head *
 298 btrfs_delayed_node_to_head(struct btrfs_delayed_ref_node *node)
 299 {
 300         WARN_ON(!btrfs_delayed_ref_is_head(node));
 301         return container_of(node, struct btrfs_delayed_ref_head, node);
 302 }
 303 #endif