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 rb_node href_node;
  87
  88         struct btrfs_delayed_extent_op *extent_op;
  89         /*
  90          * when a new extent is allocated, it is just reserved in memory
  91          * The actual extent isn't inserted into the extent allocation tree
  92          * until the delayed ref is processed.  must_insert_reserved is
  93          * used to flag a delayed ref so the accounting can be updated
  94          * when a full insert is done.
  95          *
  96          * It is possible the extent will be freed before it is ever
  97          * inserted into the extent allocation tree.  In this case
  98          * we need to update the in ram accounting to properly reflect
  99          * the free has happened.
 100          */
 101         unsigned int must_insert_reserved:1;
 102         unsigned int is_data:1;
 103 };
 104
 105 struct btrfs_delayed_tree_ref {
 106         struct btrfs_delayed_ref_node node;
 107         u64 root;
 108         u64 parent;
 109         int level;
 110 };
 111
 112 struct btrfs_delayed_data_ref {
 113         struct btrfs_delayed_ref_node node;
 114         u64 root;
 115         u64 parent;
 116         u64 objectid;
 117         u64 offset;
 118 };
 119
 120 struct btrfs_delayed_ref_root {
 121         struct rb_root root;
 122
 123         /* head ref rbtree */
 124         struct rb_root href_root;
 125
 126         /* this spin lock protects the rbtree and the entries inside */
 127         spinlock_t lock;
 128
 129         /* how many delayed ref updates we've queued, used by the
 130          * throttling code
 131          */
 132         unsigned long num_entries;
 133
 134         /* total number of head nodes in tree */
 135         unsigned long num_heads;
 136
 137         /* total number of head nodes ready for processing */
 138         unsigned long num_heads_ready;
 139
 140         /*
 141          * bumped when someone is making progress on the delayed
 142          * refs, so that other procs know they are just adding to
 143          * contention intead of helping
 144          */
 145         atomic_t procs_running_refs;
 146         atomic_t ref_seq;
 147         wait_queue_head_t wait;
 148
 149         /*
 150          * set when the tree is flushing before a transaction commit,
 151          * used by the throttling code to decide if new updates need
 152          * to be run right away
 153          */
 154         int flushing;
 155
 156         u64 run_delayed_start;
 157 };
 158
 159 extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
 160 extern struct kmem_cache *btrfs_delayed_tree_ref_cachep;
 161 extern struct kmem_cache *btrfs_delayed_data_ref_cachep;
 162 extern struct kmem_cache *btrfs_delayed_extent_op_cachep;
 163
 164 int btrfs_delayed_ref_init(void);
 165 void btrfs_delayed_ref_exit(void);
 166
 167 static inline struct btrfs_delayed_extent_op *
 168 btrfs_alloc_delayed_extent_op(void)
 169 {
 170         return kmem_cache_alloc(btrfs_delayed_extent_op_cachep, GFP_NOFS);
 171 }
 172
 173 static inline void
 174 btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op *op)
 175 {
 176         if (op)
 177                 kmem_cache_free(btrfs_delayed_extent_op_cachep, op);
 178 }
 179
 180 static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
 181 {
 182         WARN_ON(atomic_read(&ref->refs) == 0);
 183         if (atomic_dec_and_test(&ref->refs)) {
 184                 WARN_ON(ref->in_tree);
 185                 switch (ref->type) {
 186                 case BTRFS_TREE_BLOCK_REF_KEY:
 187                 case BTRFS_SHARED_BLOCK_REF_KEY:
 188                         kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
 189                         break;
 190                 case BTRFS_EXTENT_DATA_REF_KEY:
 191                 case BTRFS_SHARED_DATA_REF_KEY:
 192                         kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
 193                         break;
 194                 case 0:
 195                         kmem_cache_free(btrfs_delayed_ref_head_cachep, ref);
 196                         break;
 197                 default:
 198                         BUG();
 199                 }
 200         }
 201 }
 202
 203 int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
 204                                struct btrfs_trans_handle *trans,
 205                                u64 bytenr, u64 num_bytes, u64 parent,
 206                                u64 ref_root, int level, int action,
 207                                struct btrfs_delayed_extent_op *extent_op,
 208                                int for_cow);
 209 int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
 210                                struct btrfs_trans_handle *trans,
 211                                u64 bytenr, u64 num_bytes,
 212                                u64 parent, u64 ref_root,
 213                                u64 owner, u64 offset, int action,
 214                                struct btrfs_delayed_extent_op *extent_op,
 215                                int for_cow);
 216 int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
 217                                 struct btrfs_trans_handle *trans,
 218                                 u64 bytenr, u64 num_bytes,
 219                                 struct btrfs_delayed_extent_op *extent_op);
 220 void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
 221                               struct btrfs_fs_info *fs_info,
 222                               struct btrfs_delayed_ref_root *delayed_refs,
 223                               struct btrfs_delayed_ref_head *head);
 224
 225 struct btrfs_delayed_ref_head *
 226 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr);
 227 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
 228                            struct btrfs_delayed_ref_head *head);
 229 static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
 230 {
 231         mutex_unlock(&head->mutex);
 232 }
 233
 234 int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
 235                            struct list_head *cluster, u64 search_start);
 236 void btrfs_release_ref_cluster(struct list_head *cluster);
 237
 238 int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info,
 239                             struct btrfs_delayed_ref_root *delayed_refs,
 240                             u64 seq);
 241
 242 /*
 243  * delayed refs with a ref_seq > 0 must be held back during backref walking.
 244  * this only applies to items in one of the fs-trees. for_cow items never need
 245  * to be held back, so they won't get a ref_seq number.
 246  */
 247 static inline int need_ref_seq(int for_cow, u64 rootid)
 248 {
 249         if (for_cow)
 250                 return 0;
 251
 252         if (rootid == BTRFS_FS_TREE_OBJECTID)
 253                 return 1;
 254
 255         if ((s64)rootid >= (s64)BTRFS_FIRST_FREE_OBJECTID)
 256                 return 1;
 257
 258         return 0;
 259 }
 260
 261 /*
 262  * a node might live in a head or a regular ref, this lets you
 263  * test for the proper type to use.
 264  */
 265 static int btrfs_delayed_ref_is_head(struct btrfs_delayed_ref_node *node)
 266 {
 267         return node->is_head;
 268 }
 269
 270 /*
 271  * helper functions to cast a node into its container
 272  */
 273 static inline struct btrfs_delayed_tree_ref *
 274 btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node)
 275 {
 276         WARN_ON(btrfs_delayed_ref_is_head(node));
 277         return container_of(node, struct btrfs_delayed_tree_ref, node);
 278 }
 279
 280 static inline struct btrfs_delayed_data_ref *
 281 btrfs_delayed_node_to_data_ref(struct btrfs_delayed_ref_node *node)
 282 {
 283         WARN_ON(btrfs_delayed_ref_is_head(node));
 284         return container_of(node, struct btrfs_delayed_data_ref, node);
 285 }
 286
 287 static inline struct btrfs_delayed_ref_head *
 288 btrfs_delayed_node_to_head(struct btrfs_delayed_ref_node *node)
 289 {
 290         WARN_ON(!btrfs_delayed_ref_is_head(node));
 291         return container_of(node, struct btrfs_delayed_ref_head, node);
 292 }
 293 #endif