LXR linux/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
  27struct 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
  61struct 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 */
  76struct 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
 116struct btrfs_delayed_tree_ref {
 117        struct btrfs_delayed_ref_node node;
 118        u64 root;
 119        u64 parent;
 120        int level;
 121};
 122
 123struct 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
 131struct 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
 161extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
 162extern struct kmem_cache *btrfs_delayed_tree_ref_cachep;
 163extern struct kmem_cache *btrfs_delayed_data_ref_cachep;
 164extern struct kmem_cache *btrfs_delayed_extent_op_cachep;
 165
 166int btrfs_delayed_ref_init(void);
 167void btrfs_delayed_ref_exit(void);
 168
 169static inline struct btrfs_delayed_extent_op *
 170btrfs_alloc_delayed_extent_op(void)
 171{
 172        return kmem_cache_alloc(btrfs_delayed_extent_op_cachep, GFP_NOFS);
 173}
 174
 175static inline void
 176btrfs_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
 182static 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
 205int 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);
 211int 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);
 218int 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);
 222void 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
 227struct btrfs_delayed_ref_head *
 228btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr);
 229int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
 230                           struct btrfs_delayed_ref_head *head);
 231static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
 232{
 233        mutex_unlock(&head->mutex);
 234}
 235
 236
 237struct btrfs_delayed_ref_head *
 238btrfs_select_ref_head(struct btrfs_trans_handle *trans);
 239
 240int 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 */
 248static 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 */
 256static inline struct btrfs_delayed_tree_ref *
 257btrfs_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
 263static inline struct btrfs_delayed_data_ref *
 264btrfs_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
 270static inline struct btrfs_delayed_ref_head *
 271btrfs_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
 277