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 #include <linux/refcount.h>
  22
  23 /* these are the possible values of struct btrfs_delayed_ref_node->action */
  24 #define BTRFS_ADD_DELAYED_REF    1 /* add one backref to the tree */
  25 #define BTRFS_DROP_DELAYED_REF   2 /* delete one backref from the tree */
  26 #define BTRFS_ADD_DELAYED_EXTENT 3 /* record a full extent allocation */
  27 #define BTRFS_UPDATE_DELAYED_HEAD 4 /* not changing ref count on head ref */
  28
  29 /*
  30  * XXX: Qu: I really hate the design that ref_head and tree/data ref shares the
  31  * same ref_node structure.
  32  * Ref_head is in a higher logic level than tree/data ref, and duplicated
  33  * bytenr/num_bytes in ref_node is really a waste or memory, they should be
  34  * referred from ref_head.
  35  * This gets more disgusting after we use list to store tree/data ref in
  36  * ref_head. Must clean this mess up later.
  37  */
  38 struct btrfs_delayed_ref_node {
  39         /*data/tree ref use list, stored in ref_head->ref_list. */
  40         struct list_head list;
  41         /*
  42          * If action is BTRFS_ADD_DELAYED_REF, also link this node to
  43          * ref_head->ref_add_list, then we do not need to iterate the
  44          * whole ref_head->ref_list to find BTRFS_ADD_DELAYED_REF nodes.
  45          */
  46         struct list_head add_list;
  47
  48         /* the starting bytenr of the extent */
  49         u64 bytenr;
  50
  51         /* the size of the extent */
  52         u64 num_bytes;
  53
  54         /* seq number to keep track of insertion order */
  55         u64 seq;
  56
  57         /* ref count on this data structure */
  58         refcount_t refs;
  59
  60         /*
  61          * how many refs is this entry adding or deleting.  For
  62          * head refs, this may be a negative number because it is keeping
  63          * track of the total mods done to the reference count.
  64          * For individual refs, this will always be a positive number
  65          *
  66          * It may be more than one, since it is possible for a single
  67          * parent to have more than one ref on an extent
  68          */
  69         int ref_mod;
  70
  71         unsigned int action:8;
  72         unsigned int type:8;
  73         /* is this node still in the rbtree? */
  74         unsigned int is_head:1;
  75         unsigned int in_tree:1;
  76 };
  77
  78 struct btrfs_delayed_extent_op {
  79         struct btrfs_disk_key key;
  80         u8 level;
  81         bool update_key;
  82         bool update_flags;
  83         bool is_data;
  84         u64 flags_to_set;
  85 };
  86
  87 /*
  88  * the head refs are used to hold a lock on a given extent, which allows us
  89  * to make sure that only one process is running the delayed refs
  90  * at a time for a single extent.  They also store the sum of all the
  91  * reference count modifications we've queued up.
  92  */
  93 struct btrfs_delayed_ref_head {
  94         struct btrfs_delayed_ref_node node;
  95
  96         /*
  97          * the mutex is held while running the refs, and it is also
  98          * held when checking the sum of reference modifications.
  99          */
 100         struct mutex mutex;
 101
 102         spinlock_t lock;
 103         struct list_head ref_list;
 104         /* accumulate add BTRFS_ADD_DELAYED_REF nodes to this ref_add_list. */
 105         struct list_head ref_add_list;
 106
 107         struct rb_node href_node;
 108
 109         struct btrfs_delayed_extent_op *extent_op;
 110
 111         /*
 112          * This is used to track the final ref_mod from all the refs associated
 113          * with this head ref, this is not adjusted as delayed refs are run,
 114          * this is meant to track if we need to do the csum accounting or not.
 115          */
 116         int total_ref_mod;
 117
 118         /*
 119          * For qgroup reserved space freeing.
 120          *
 121          * ref_root and reserved will be recorded after
 122          * BTRFS_ADD_DELAYED_EXTENT is called.
 123          * And will be used to free reserved qgroup space at
 124          * run_delayed_refs() time.
 125          */
 126         u64 qgroup_ref_root;
 127         u64 qgroup_reserved;
 128
 129         /*
 130          * when a new extent is allocated, it is just reserved in memory
 131          * The actual extent isn't inserted into the extent allocation tree
 132          * until the delayed ref is processed.  must_insert_reserved is
 133          * used to flag a delayed ref so the accounting can be updated
 134          * when a full insert is done.
 135          *
 136          * It is possible the extent will be freed before it is ever
 137          * inserted into the extent allocation tree.  In this case
 138          * we need to update the in ram accounting to properly reflect
 139          * the free has happened.
 140          */
 141         unsigned int must_insert_reserved:1;
 142         unsigned int is_data:1;
 143         unsigned int processing:1;
 144 };
 145
 146 struct btrfs_delayed_tree_ref {
 147         struct btrfs_delayed_ref_node node;
 148         u64 root;
 149         u64 parent;
 150         int level;
 151 };
 152
 153 struct btrfs_delayed_data_ref {
 154         struct btrfs_delayed_ref_node node;
 155         u64 root;
 156         u64 parent;
 157         u64 objectid;
 158         u64 offset;
 159 };
 160
 161 struct btrfs_delayed_ref_root {
 162         /* head ref rbtree */
 163         struct rb_root href_root;
 164
 165         /* dirty extent records */
 166         struct rb_root dirty_extent_root;
 167
 168         /* this spin lock protects the rbtree and the entries inside */
 169         spinlock_t lock;
 170
 171         /* how many delayed ref updates we've queued, used by the
 172          * throttling code
 173          */
 174         atomic_t num_entries;
 175
 176         /* total number of head nodes in tree */
 177         unsigned long num_heads;
 178
 179         /* total number of head nodes ready for processing */
 180         unsigned long num_heads_ready;
 181
 182         u64 pending_csums;
 183
 184         /*
 185          * set when the tree is flushing before a transaction commit,
 186          * used by the throttling code to decide if new updates need
 187          * to be run right away
 188          */
 189         int flushing;
 190
 191         u64 run_delayed_start;
 192
 193         /*
 194          * To make qgroup to skip given root.
 195          * This is for snapshot, as btrfs_qgroup_inherit() will manually
 196          * modify counters for snapshot and its source, so we should skip
 197          * the snapshot in new_root/old_roots or it will get calculated twice
 198          */
 199         u64 qgroup_to_skip;
 200 };
 201
 202 extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
 203 extern struct kmem_cache *btrfs_delayed_tree_ref_cachep;
 204 extern struct kmem_cache *btrfs_delayed_data_ref_cachep;
 205 extern struct kmem_cache *btrfs_delayed_extent_op_cachep;
 206
 207 int btrfs_delayed_ref_init(void);
 208 void btrfs_delayed_ref_exit(void);
 209
 210 static inline struct btrfs_delayed_extent_op *
 211 btrfs_alloc_delayed_extent_op(void)
 212 {
 213         return kmem_cache_alloc(btrfs_delayed_extent_op_cachep, GFP_NOFS);
 214 }
 215
 216 static inline void
 217 btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op *op)
 218 {
 219         if (op)
 220                 kmem_cache_free(btrfs_delayed_extent_op_cachep, op);
 221 }
 222
 223 static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
 224 {
 225         WARN_ON(refcount_read(&ref->refs) == 0);
 226         if (refcount_dec_and_test(&ref->refs)) {
 227                 WARN_ON(ref->in_tree);
 228                 switch (ref->type) {
 229                 case BTRFS_TREE_BLOCK_REF_KEY:
 230                 case BTRFS_SHARED_BLOCK_REF_KEY:
 231                         kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
 232                         break;
 233                 case BTRFS_EXTENT_DATA_REF_KEY:
 234                 case BTRFS_SHARED_DATA_REF_KEY:
 235                         kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
 236                         break;
 237                 case 0:
 238                         kmem_cache_free(btrfs_delayed_ref_head_cachep, ref);
 239                         break;
 240                 default:
 241                         BUG();
 242                 }
 243         }
 244 }
 245
 246 int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
 247                                struct btrfs_trans_handle *trans,
 248                                u64 bytenr, u64 num_bytes, u64 parent,
 249                                u64 ref_root, int level, int action,
 250                                struct btrfs_delayed_extent_op *extent_op);
 251 int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
 252                                struct btrfs_trans_handle *trans,
 253                                u64 bytenr, u64 num_bytes,
 254                                u64 parent, u64 ref_root,
 255                                u64 owner, u64 offset, u64 reserved, int action);
 256 int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
 257                                 struct btrfs_trans_handle *trans,
 258                                 u64 bytenr, u64 num_bytes,
 259                                 struct btrfs_delayed_extent_op *extent_op);
 260 void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
 261                               struct btrfs_fs_info *fs_info,
 262                               struct btrfs_delayed_ref_root *delayed_refs,
 263                               struct btrfs_delayed_ref_head *head);
 264
 265 struct btrfs_delayed_ref_head *
 266 btrfs_find_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
 267                             u64 bytenr);
 268 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
 269                            struct btrfs_delayed_ref_head *head);
 270 static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
 271 {
 272         mutex_unlock(&head->mutex);
 273 }
 274
 275
 276 struct btrfs_delayed_ref_head *
 277 btrfs_select_ref_head(struct btrfs_trans_handle *trans);
 278
 279 int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info,
 280                             struct btrfs_delayed_ref_root *delayed_refs,
 281                             u64 seq);
 282
 283 /*
 284  * a node might live in a head or a regular ref, this lets you
 285  * test for the proper type to use.
 286  */
 287 static int btrfs_delayed_ref_is_head(struct btrfs_delayed_ref_node *node)
 288 {
 289         return node->is_head;
 290 }
 291
 292 /*
 293  * helper functions to cast a node into its container
 294  */
 295 static inline struct btrfs_delayed_tree_ref *
 296 btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node)
 297 {
 298         WARN_ON(btrfs_delayed_ref_is_head(node));
 299         return container_of(node, struct btrfs_delayed_tree_ref, node);
 300 }
 301
 302 static inline struct btrfs_delayed_data_ref *
 303 btrfs_delayed_node_to_data_ref(struct btrfs_delayed_ref_node *node)
 304 {
 305         WARN_ON(btrfs_delayed_ref_is_head(node));
 306         return container_of(node, struct btrfs_delayed_data_ref, node);
 307 }
 308
 309 static inline struct btrfs_delayed_ref_head *
 310 btrfs_delayed_node_to_head(struct btrfs_delayed_ref_node *node)
 311 {
 312         WARN_ON(!btrfs_delayed_ref_is_head(node));
 313         return container_of(node, struct btrfs_delayed_ref_head, node);
 314 }
 315 #endif