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         /* is this node still in the rbtree? */
  72         unsigned int is_head:1;
  73         unsigned int in_tree:1;
  74 };
  75
  76 struct btrfs_delayed_extent_op {
  77         struct btrfs_disk_key key;
  78         u8 level;
  79         bool update_key;
  80         bool update_flags;
  81         bool is_data;
  82         u64 flags_to_set;
  83 };
  84
  85 /*
  86  * the head refs are used to hold a lock on a given extent, which allows us
  87  * to make sure that only one process is running the delayed refs
  88  * at a time for a single extent.  They also store the sum of all the
  89  * reference count modifications we've queued up.
  90  */
  91 struct btrfs_delayed_ref_head {
  92         struct btrfs_delayed_ref_node node;
  93
  94         /*
  95          * the mutex is held while running the refs, and it is also
  96          * held when checking the sum of reference modifications.
  97          */
  98         struct mutex mutex;
  99
 100         spinlock_t lock;
 101         struct list_head ref_list;
 102
 103         struct rb_node href_node;
 104
 105         struct btrfs_delayed_extent_op *extent_op;
 106
 107         /*
 108          * This is used to track the final ref_mod from all the refs associated
 109          * with this head ref, this is not adjusted as delayed refs are run,
 110          * this is meant to track if we need to do the csum accounting or not.
 111          */
 112         int total_ref_mod;
 113
 114         /*
 115          * For qgroup reserved space freeing.
 116          *
 117          * ref_root and reserved will be recorded after
 118          * BTRFS_ADD_DELAYED_EXTENT is called.
 119          * And will be used to free reserved qgroup space at
 120          * run_delayed_refs() time.
 121          */
 122         u64 qgroup_ref_root;
 123         u64 qgroup_reserved;
 124
 125         /*
 126          * when a new extent is allocated, it is just reserved in memory
 127          * The actual extent isn't inserted into the extent allocation tree
 128          * until the delayed ref is processed.  must_insert_reserved is
 129          * used to flag a delayed ref so the accounting can be updated
 130          * when a full insert is done.
 131          *
 132          * It is possible the extent will be freed before it is ever
 133          * inserted into the extent allocation tree.  In this case
 134          * we need to update the in ram accounting to properly reflect
 135          * the free has happened.
 136          */
 137         unsigned int must_insert_reserved:1;
 138         unsigned int is_data:1;
 139         unsigned int processing:1;
 140 };
 141
 142 struct btrfs_delayed_tree_ref {
 143         struct btrfs_delayed_ref_node node;
 144         u64 root;
 145         u64 parent;
 146         int level;
 147 };
 148
 149 struct btrfs_delayed_data_ref {
 150         struct btrfs_delayed_ref_node node;
 151         u64 root;
 152         u64 parent;
 153         u64 objectid;
 154         u64 offset;
 155 };
 156
 157 struct btrfs_delayed_ref_root {
 158         /* head ref rbtree */
 159         struct rb_root href_root;
 160
 161         /* dirty extent records */
 162         struct rb_root dirty_extent_root;
 163
 164         /* this spin lock protects the rbtree and the entries inside */
 165         spinlock_t lock;
 166
 167         /* how many delayed ref updates we've queued, used by the
 168          * throttling code
 169          */
 170         atomic_t num_entries;
 171
 172         /* total number of head nodes in tree */
 173         unsigned long num_heads;
 174
 175         /* total number of head nodes ready for processing */
 176         unsigned long num_heads_ready;
 177
 178         u64 pending_csums;
 179
 180         /*
 181          * set when the tree is flushing before a transaction commit,
 182          * used by the throttling code to decide if new updates need
 183          * to be run right away
 184          */
 185         int flushing;
 186
 187         u64 run_delayed_start;
 188
 189         /*
 190          * To make qgroup to skip given root.
 191          * This is for snapshot, as btrfs_qgroup_inherit() will manually
 192          * modify counters for snapshot and its source, so we should skip
 193          * the snapshot in new_root/old_roots or it will get calculated twice
 194          */
 195         u64 qgroup_to_skip;
 196 };
 197
 198 extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
 199 extern struct kmem_cache *btrfs_delayed_tree_ref_cachep;
 200 extern struct kmem_cache *btrfs_delayed_data_ref_cachep;
 201 extern struct kmem_cache *btrfs_delayed_extent_op_cachep;
 202
 203 int btrfs_delayed_ref_init(void);
 204 void btrfs_delayed_ref_exit(void);
 205
 206 static inline struct btrfs_delayed_extent_op *
 207 btrfs_alloc_delayed_extent_op(void)
 208 {
 209         return kmem_cache_alloc(btrfs_delayed_extent_op_cachep, GFP_NOFS);
 210 }
 211
 212 static inline void
 213 btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op *op)
 214 {
 215         if (op)
 216                 kmem_cache_free(btrfs_delayed_extent_op_cachep, op);
 217 }
 218
 219 static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
 220 {
 221         WARN_ON(atomic_read(&ref->refs) == 0);
 222         if (atomic_dec_and_test(&ref->refs)) {
 223                 WARN_ON(ref->in_tree);
 224                 switch (ref->type) {
 225                 case BTRFS_TREE_BLOCK_REF_KEY:
 226                 case BTRFS_SHARED_BLOCK_REF_KEY:
 227                         kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
 228                         break;
 229                 case BTRFS_EXTENT_DATA_REF_KEY:
 230                 case BTRFS_SHARED_DATA_REF_KEY:
 231                         kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
 232                         break;
 233                 case 0:
 234                         kmem_cache_free(btrfs_delayed_ref_head_cachep, ref);
 235                         break;
 236                 default:
 237                         BUG();
 238                 }
 239         }
 240 }
 241
 242 int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
 243                                struct btrfs_trans_handle *trans,
 244                                u64 bytenr, u64 num_bytes, u64 parent,
 245                                u64 ref_root, int level, int action,
 246                                struct btrfs_delayed_extent_op *extent_op);
 247 int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
 248                                struct btrfs_trans_handle *trans,
 249                                u64 bytenr, u64 num_bytes,
 250                                u64 parent, u64 ref_root,
 251                                u64 owner, u64 offset, u64 reserved, int action,
 252                                struct btrfs_delayed_extent_op *extent_op);
 253 int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
 254                                 struct btrfs_trans_handle *trans,
 255                                 u64 bytenr, u64 num_bytes,
 256                                 struct btrfs_delayed_extent_op *extent_op);
 257 void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
 258                               struct btrfs_fs_info *fs_info,
 259                               struct btrfs_delayed_ref_root *delayed_refs,
 260                               struct btrfs_delayed_ref_head *head);
 261
 262 struct btrfs_delayed_ref_head *
 263 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr);
 264 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
 265                            struct btrfs_delayed_ref_head *head);
 266 static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
 267 {
 268         mutex_unlock(&head->mutex);
 269 }
 270
 271
 272 struct btrfs_delayed_ref_head *
 273 btrfs_select_ref_head(struct btrfs_trans_handle *trans);
 274
 275 int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info,
 276                             struct btrfs_delayed_ref_root *delayed_refs,
 277                             u64 seq);
 278
 279 /*
 280  * a node might live in a head or a regular ref, this lets you
 281  * test for the proper type to use.
 282  */
 283 static int btrfs_delayed_ref_is_head(struct btrfs_delayed_ref_node *node)
 284 {
 285         return node->is_head;
 286 }
 287
 288 /*
 289  * helper functions to cast a node into its container
 290  */
 291 static inline struct btrfs_delayed_tree_ref *
 292 btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node)
 293 {
 294         WARN_ON(btrfs_delayed_ref_is_head(node));
 295         return container_of(node, struct btrfs_delayed_tree_ref, node);
 296 }
 297
 298 static inline struct btrfs_delayed_data_ref *
 299 btrfs_delayed_node_to_data_ref(struct btrfs_delayed_ref_node *node)
 300 {
 301         WARN_ON(btrfs_delayed_ref_is_head(node));
 302         return container_of(node, struct btrfs_delayed_data_ref, node);
 303 }
 304
 305 static inline struct btrfs_delayed_ref_head *
 306 btrfs_delayed_node_to_head(struct btrfs_delayed_ref_node *node)
 307 {
 308         WARN_ON(!btrfs_delayed_ref_is_head(node));
 309         return container_of(node, struct btrfs_delayed_ref_head, node);
 310 }
 311 #endif