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 struct btrfs_delayed_ref_node {
  28         struct rb_node rb_node;
  29
  30         /* the starting bytenr of the extent */
  31         u64 bytenr;
  32
  33         /* the size of the extent */
  34         u64 num_bytes;
  35
  36         /* seq number to keep track of insertion order */
  37         u64 seq;
  38
  39         /* ref count on this data structure */
  40         atomic_t refs;
  41
  42         /*
  43          * how many refs is this entry adding or deleting.  For
  44          * head refs, this may be a negative number because it is keeping
  45          * track of the total mods done to the reference count.
  46          * For individual refs, this will always be a positive number
  47          *
  48          * It may be more than one, since it is possible for a single
  49          * parent to have more than one ref on an extent
  50          */
  51         int ref_mod;
  52
  53         unsigned int action:8;
  54         unsigned int type:8;
  55         unsigned int no_quota:1;
  56         /* is this node still in the rbtree? */
  57         unsigned int is_head:1;
  58         unsigned int in_tree:1;
  59 };
  60
  61 struct btrfs_delayed_extent_op {
  62         struct btrfs_disk_key key;
  63         u64 flags_to_set;
  64         int level;
  65         unsigned int update_key:1;
  66         unsigned int update_flags:1;
  67         unsigned int is_data:1;
  68 };
  69
  70 /*
  71  * the head refs are used to hold a lock on a given extent, which allows us
  72  * to make sure that only one process is running the delayed refs
  73  * at a time for a single extent.  They also store the sum of all the
  74  * reference count modifications we've queued up.
  75  */
  76 struct btrfs_delayed_ref_head {
  77         struct btrfs_delayed_ref_node node;
  78
  79         /*
  80          * the mutex is held while running the refs, and it is also
  81          * held when checking the sum of reference modifications.
  82          */
  83         struct mutex mutex;
  84
  85         spinlock_t lock;
  86         struct rb_root ref_root;
  87
  88         struct rb_node href_node;
  89
  90         struct btrfs_delayed_extent_op *extent_op;
  91
  92         /*
  93          * This is used to track the final ref_mod from all the refs associated
  94          * with this head ref, this is not adjusted as delayed refs are run,
  95          * this is meant to track if we need to do the csum accounting or not.
  96          */
  97         int total_ref_mod;
  98
  99         /*
 100          * when a new extent is allocated, it is just reserved in memory
 101          * The actual extent isn't inserted into the extent allocation tree
 102          * until the delayed ref is processed.  must_insert_reserved is
 103          * used to flag a delayed ref so the accounting can be updated
 104          * when a full insert is done.
 105          *
 106          * It is possible the extent will be freed before it is ever
 107          * inserted into the extent allocation tree.  In this case
 108          * we need to update the in ram accounting to properly reflect
 109          * the free has happened.
 110          */
 111         unsigned int must_insert_reserved:1;
 112         unsigned int is_data:1;
 113         unsigned int processing:1;
 114 };
 115
 116 struct btrfs_delayed_tree_ref {
 117         struct btrfs_delayed_ref_node node;
 118         u64 root;
 119         u64 parent;
 120         int level;
 121 };
 122
 123 struct btrfs_delayed_data_ref {
 124         struct btrfs_delayed_ref_node node;
 125         u64 root;
 126         u64 parent;
 127         u64 objectid;
 128         u64 offset;
 129 };
 130
 131 struct btrfs_delayed_ref_root {
 132         /* head ref rbtree */
 133         struct rb_root href_root;
 134
 135         /* this spin lock protects the rbtree and the entries inside */
 136         spinlock_t lock;
 137
 138         /* how many delayed ref updates we've queued, used by the
 139          * throttling code
 140          */
 141         atomic_t num_entries;
 142
 143         /* total number of head nodes in tree */
 144         unsigned long num_heads;
 145
 146         /* total number of head nodes ready for processing */
 147         unsigned long num_heads_ready;
 148
 149         u64 pending_csums;
 150
 151         /*
 152          * set when the tree is flushing before a transaction commit,
 153          * used by the throttling code to decide if new updates need
 154          * to be run right away
 155          */
 156         int flushing;
 157
 158         u64 run_delayed_start;
 159 };
 160
 161 extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
 162 extern struct kmem_cache *btrfs_delayed_tree_ref_cachep;
 163 extern struct kmem_cache *btrfs_delayed_data_ref_cachep;
 164 extern struct kmem_cache *btrfs_delayed_extent_op_cachep;
 165
 166 int btrfs_delayed_ref_init(void);
 167 void btrfs_delayed_ref_exit(void);
 168
 169 static inline struct btrfs_delayed_extent_op *
 170 btrfs_alloc_delayed_extent_op(void)
 171 {
 172         return kmem_cache_alloc(btrfs_delayed_extent_op_cachep, GFP_NOFS);
 173 }
 174
 175 static inline void
 176 btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op *op)
 177 {
 178         if (op)
 179                 kmem_cache_free(btrfs_delayed_extent_op_cachep, op);
 180 }
 181
 182 static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
 183 {
 184         WARN_ON(atomic_read(&ref->refs) == 0);
 185         if (atomic_dec_and_test(&ref->refs)) {
 186                 WARN_ON(ref->in_tree);
 187                 switch (ref->type) {
 188                 case BTRFS_TREE_BLOCK_REF_KEY:
 189                 case BTRFS_SHARED_BLOCK_REF_KEY:
 190                         kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
 191                         break;
 192                 case BTRFS_EXTENT_DATA_REF_KEY:
 193                 case BTRFS_SHARED_DATA_REF_KEY:
 194                         kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
 195                         break;
 196                 case 0:
 197                         kmem_cache_free(btrfs_delayed_ref_head_cachep, ref);
 198                         break;
 199                 default:
 200                         BUG();
 201                 }
 202         }
 203 }
 204
 205 int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
 206                                struct btrfs_trans_handle *trans,
 207                                u64 bytenr, u64 num_bytes, u64 parent,
 208                                u64 ref_root, int level, int action,
 209                                struct btrfs_delayed_extent_op *extent_op,
 210                                int no_quota);
 211 int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
 212                                struct btrfs_trans_handle *trans,
 213                                u64 bytenr, u64 num_bytes,
 214                                u64 parent, u64 ref_root,
 215                                u64 owner, u64 offset, int action,
 216                                struct btrfs_delayed_extent_op *extent_op,
 217                                int no_quota);
 218 int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
 219                                 struct btrfs_trans_handle *trans,
 220                                 u64 bytenr, u64 num_bytes,
 221                                 struct btrfs_delayed_extent_op *extent_op);
 222 void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
 223                               struct btrfs_fs_info *fs_info,
 224                               struct btrfs_delayed_ref_root *delayed_refs,
 225                               struct btrfs_delayed_ref_head *head);
 226
 227 struct btrfs_delayed_ref_head *
 228 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr);
 229 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
 230                            struct btrfs_delayed_ref_head *head);
 231 static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
 232 {
 233         mutex_unlock(&head->mutex);
 234 }
 235
 236
 237 struct btrfs_delayed_ref_head *
 238 btrfs_select_ref_head(struct btrfs_trans_handle *trans);
 239
 240 int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info,
 241                             struct btrfs_delayed_ref_root *delayed_refs,
 242                             u64 seq);
 243
 244 /*
 245  * a node might live in a head or a regular ref, this lets you
 246  * test for the proper type to use.
 247  */
 248 static int btrfs_delayed_ref_is_head(struct btrfs_delayed_ref_node *node)
 249 {
 250         return node->is_head;
 251 }
 252
 253 /*
 254  * helper functions to cast a node into its container
 255  */
 256 static inline struct btrfs_delayed_tree_ref *
 257 btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node)
 258 {
 259         WARN_ON(btrfs_delayed_ref_is_head(node));
 260         return container_of(node, struct btrfs_delayed_tree_ref, node);
 261 }
 262
 263 static inline struct btrfs_delayed_data_ref *
 264 btrfs_delayed_node_to_data_ref(struct btrfs_delayed_ref_node *node)
 265 {
 266         WARN_ON(btrfs_delayed_ref_is_head(node));
 267         return container_of(node, struct btrfs_delayed_data_ref, node);
 268 }
 269
 270 static inline struct btrfs_delayed_ref_head *
 271 btrfs_delayed_node_to_head(struct btrfs_delayed_ref_node *node)
 272 {
 273         WARN_ON(!btrfs_delayed_ref_is_head(node));
 274         return container_of(node, struct btrfs_delayed_ref_head, node);
 275 }
 276 #endif