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