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        /* is this node still in the rbtree? */
  56        unsigned int is_head:1;
  57        unsigned int in_tree:1;
  58};
  59
  60struct 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 */
  75struct 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
 103struct btrfs_delayed_tree_ref {
 104        struct btrfs_delayed_ref_node node;
 105        u64 root;
 106        u64 parent;
 107        int level;
 108};
 109
 110struct 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
 118struct 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
 154extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
 155extern struct kmem_cache *btrfs_delayed_tree_ref_cachep;
 156extern struct kmem_cache *btrfs_delayed_data_ref_cachep;
 157extern struct kmem_cache *btrfs_delayed_extent_op_cachep;
 158
 159int btrfs_delayed_ref_init(void);
 160void btrfs_delayed_ref_exit(void);
 161
 162static inline struct btrfs_delayed_extent_op *
 163btrfs_alloc_delayed_extent_op(void)
 164{
 165        return kmem_cache_alloc(btrfs_delayed_extent_op_cachep, GFP_NOFS);
 166}
 167
 168static inline void
 169btrfs_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
 175static 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
 198int 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);
 204int 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);
 211int 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);
 215void 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
 220struct btrfs_delayed_ref_head *
 221btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr);
 222int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
 223                           struct btrfs_delayed_ref_head *head);
 224static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
 225{
 226        mutex_unlock(&head->mutex);
 227}
 228
 229int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
 230                           struct list_head *cluster, u64 search_start);
 231void btrfs_release_ref_cluster(struct list_head *cluster);
 232
 233int 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 */
 242static 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 */
 260static 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 */
 268static inline struct btrfs_delayed_tree_ref *
 269btrfs_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
 275static inline struct btrfs_delayed_data_ref *
 276btrfs_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
 282static inline struct btrfs_delayed_ref_head *
 283btrfs_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
 289