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