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         /* is this node still in the rbtree? */
  56         unsigned int is_head:1;
  57         unsigned int in_tree:1;
  58 };
  59
  60 struct btrfs_delayed_extent_op {
  61         struct btrfs_disk_key key;
  62         u64 flags_to_set;
  63         unsigned int update_key:1;
  64         unsigned int update_flags:1;
  65         unsigned int is_data:1;
  66 };
  67
  68 /*
  69  * the head refs are used to hold a lock on a given extent, which allows us
  70  * to make sure that only one process is running the delayed refs
  71  * at a time for a single extent.  They also store the sum of all the
  72  * reference count modifications we've queued up.
  73  */
  74 struct btrfs_delayed_ref_head {
  75         struct btrfs_delayed_ref_node node;
  76
  77         /*
  78          * the mutex is held while running the refs, and it is also
  79          * held when checking the sum of reference modifications.
  80          */
  81         struct mutex mutex;
  82
  83         struct list_head cluster;
  84
  85         struct btrfs_delayed_extent_op *extent_op;
  86         /*
  87          * when a new extent is allocated, it is just reserved in memory
  88          * The actual extent isn't inserted into the extent allocation tree
  89          * until the delayed ref is processed.  must_insert_reserved is
  90          * used to flag a delayed ref so the accounting can be updated
  91          * when a full insert is done.
  92          *
  93          * It is possible the extent will be freed before it is ever
  94          * inserted into the extent allocation tree.  In this case
  95          * we need to update the in ram accounting to properly reflect
  96          * the free has happened.
  97          */
  98         unsigned int must_insert_reserved:1;
  99         unsigned int is_data:1;
 100 };
 101
 102 struct btrfs_delayed_tree_ref {
 103         struct btrfs_delayed_ref_node node;
 104         u64 root;
 105         u64 parent;
 106         int level;
 107 };
 108
 109 struct btrfs_delayed_data_ref {
 110         struct btrfs_delayed_ref_node node;
 111         u64 root;
 112         u64 parent;
 113         u64 objectid;
 114         u64 offset;
 115 };
 116
 117 struct btrfs_delayed_ref_root {
 118         struct rb_root root;
 119
 120         /* this spin lock protects the rbtree and the entries inside */
 121         spinlock_t lock;
 122
 123         /* how many delayed ref updates we've queued, used by the
 124          * throttling code
 125          */
 126         unsigned long num_entries;
 127
 128         /* total number of head nodes in tree */
 129         unsigned long num_heads;
 130
 131         /* total number of head nodes ready for processing */
 132         unsigned long num_heads_ready;
 133
 134         /*
 135          * bumped when someone is making progress on the delayed
 136          * refs, so that other procs know they are just adding to
 137          * contention intead of helping
 138          */
 139         atomic_t procs_running_refs;
 140         atomic_t ref_seq;
 141         wait_queue_head_t wait;
 142
 143         /*
 144          * set when the tree is flushing before a transaction commit,
 145          * used by the throttling code to decide if new updates need
 146          * to be run right away
 147          */
 148         int flushing;
 149
 150         u64 run_delayed_start;
 151 };
 152
 153 extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
 154 extern struct kmem_cache *btrfs_delayed_tree_ref_cachep;
 155 extern struct kmem_cache *btrfs_delayed_data_ref_cachep;
 156 extern struct kmem_cache *btrfs_delayed_extent_op_cachep;
 157
 158 int btrfs_delayed_ref_init(void);
 159 void btrfs_delayed_ref_exit(void);
 160
 161 static inline struct btrfs_delayed_extent_op *
 162 btrfs_alloc_delayed_extent_op(void)
 163 {
 164         return kmem_cache_alloc(btrfs_delayed_extent_op_cachep, GFP_NOFS);
 165 }
 166
 167 static inline void
 168 btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op *op)
 169 {
 170         if (op)
 171                 kmem_cache_free(btrfs_delayed_extent_op_cachep, op);
 172 }
 173
 174 static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
 175 {
 176         WARN_ON(atomic_read(&ref->refs) == 0);
 177         if (atomic_dec_and_test(&ref->refs)) {
 178                 WARN_ON(ref->in_tree);
 179                 switch (ref->type) {
 180                 case BTRFS_TREE_BLOCK_REF_KEY:
 181                 case BTRFS_SHARED_BLOCK_REF_KEY:
 182                         kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
 183                         break;
 184                 case BTRFS_EXTENT_DATA_REF_KEY:
 185                 case BTRFS_SHARED_DATA_REF_KEY:
 186                         kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
 187                         break;
 188                 case 0:
 189                         kmem_cache_free(btrfs_delayed_ref_head_cachep, ref);
 190                         break;
 191                 default:
 192                         BUG();
 193                 }
 194         }
 195 }
 196
 197 int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
 198                                struct btrfs_trans_handle *trans,
 199                                u64 bytenr, u64 num_bytes, u64 parent,
 200                                u64 ref_root, int level, int action,
 201                                struct btrfs_delayed_extent_op *extent_op,
 202                                int for_cow);
 203 int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
 204                                struct btrfs_trans_handle *trans,
 205                                u64 bytenr, u64 num_bytes,
 206                                u64 parent, u64 ref_root,
 207                                u64 owner, u64 offset, int action,
 208                                struct btrfs_delayed_extent_op *extent_op,
 209                                int for_cow);
 210 int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
 211                                 struct btrfs_trans_handle *trans,
 212                                 u64 bytenr, u64 num_bytes,
 213                                 struct btrfs_delayed_extent_op *extent_op);
 214 void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
 215                               struct btrfs_fs_info *fs_info,
 216                               struct btrfs_delayed_ref_root *delayed_refs,
 217                               struct btrfs_delayed_ref_head *head);
 218
 219 struct btrfs_delayed_ref_head *
 220 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr);
 221 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
 222                            struct btrfs_delayed_ref_head *head);
 223 static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
 224 {
 225         mutex_unlock(&head->mutex);
 226 }
 227
 228 int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
 229                            struct list_head *cluster, u64 search_start);
 230 void btrfs_release_ref_cluster(struct list_head *cluster);
 231
 232 int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info,
 233                             struct btrfs_delayed_ref_root *delayed_refs,
 234                             u64 seq);
 235
 236 /*
 237  * delayed refs with a ref_seq > 0 must be held back during backref walking.
 238  * this only applies to items in one of the fs-trees. for_cow items never need
 239  * to be held back, so they won't get a ref_seq number.
 240  */
 241 static inline int need_ref_seq(int for_cow, u64 rootid)
 242 {
 243         if (for_cow)
 244                 return 0;
 245
 246         if (rootid == BTRFS_FS_TREE_OBJECTID)
 247                 return 1;
 248
 249         if ((s64)rootid >= (s64)BTRFS_FIRST_FREE_OBJECTID)
 250                 return 1;
 251
 252         return 0;
 253 }
 254
 255 /*
 256  * a node might live in a head or a regular ref, this lets you
 257  * test for the proper type to use.
 258  */
 259 static int btrfs_delayed_ref_is_head(struct btrfs_delayed_ref_node *node)
 260 {
 261         return node->is_head;
 262 }
 263
 264 /*
 265  * helper functions to cast a node into its container
 266  */
 267 static inline struct btrfs_delayed_tree_ref *
 268 btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node)
 269 {
 270         WARN_ON(btrfs_delayed_ref_is_head(node));
 271         return container_of(node, struct btrfs_delayed_tree_ref, node);
 272 }
 273
 274 static inline struct btrfs_delayed_data_ref *
 275 btrfs_delayed_node_to_data_ref(struct btrfs_delayed_ref_node *node)
 276 {
 277         WARN_ON(btrfs_delayed_ref_is_head(node));
 278         return container_of(node, struct btrfs_delayed_data_ref, node);
 279 }
 280
 281 static inline struct btrfs_delayed_ref_head *
 282 btrfs_delayed_node_to_head(struct btrfs_delayed_ref_node *node)
 283 {
 284         WARN_ON(!btrfs_delayed_ref_is_head(node));
 285         return container_of(node, struct btrfs_delayed_ref_head, node);
 286 }
 287 #endif