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->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        /* ref count on this data structure */
  37        atomic_t refs;
  38
  39        /*
  40         * how many refs is this entry adding or deleting.  For
  41         * head refs, this may be a negative number because it is keeping
  42         * track of the total mods done to the reference count.
  43         * For individual refs, this will always be a positive number
  44         *
  45         * It may be more than one, since it is possible for a single
  46         * parent to have more than one ref on an extent
  47         */
  48        int ref_mod;
  49
  50        unsigned int action:8;
  51        unsigned int type:8;
  52        /* is this node still in the rbtree? */
  53        unsigned int is_head:1;
  54        unsigned int in_tree:1;
  55};
  56
  57struct btrfs_delayed_extent_op {
  58        struct btrfs_disk_key key;
  59        u64 flags_to_set;
  60        unsigned int update_key:1;
  61        unsigned int update_flags:1;
  62        unsigned int is_data:1;
  63};
  64
  65/*
  66 * the head refs are used to hold a lock on a given extent, which allows us
  67 * to make sure that only one process is running the delayed refs
  68 * at a time for a single extent.  They also store the sum of all the
  69 * reference count modifications we've queued up.
  70 */
  71struct btrfs_delayed_ref_head {
  72        struct btrfs_delayed_ref_node node;
  73
  74        /*
  75         * the mutex is held while running the refs, and it is also
  76         * held when checking the sum of reference modifications.
  77         */
  78        struct mutex mutex;
  79
  80        struct list_head cluster;
  81
  82        struct btrfs_delayed_extent_op *extent_op;
  83        /*
  84         * when a new extent is allocated, it is just reserved in memory
  85         * The actual extent isn't inserted into the extent allocation tree
  86         * until the delayed ref is processed.  must_insert_reserved is
  87         * used to flag a delayed ref so the accounting can be updated
  88         * when a full insert is done.
  89         *
  90         * It is possible the extent will be freed before it is ever
  91         * inserted into the extent allocation tree.  In this case
  92         * we need to update the in ram accounting to properly reflect
  93         * the free has happened.
  94         */
  95        unsigned int must_insert_reserved:1;
  96        unsigned int is_data:1;
  97};
  98
  99struct btrfs_delayed_tree_ref {
 100        struct btrfs_delayed_ref_node node;
 101        union {
 102                u64 root;
 103                u64 parent;
 104        };
 105        int level;
 106};
 107
 108struct btrfs_delayed_data_ref {
 109        struct btrfs_delayed_ref_node node;
 110        union {
 111                u64 root;
 112                u64 parent;
 113        };
 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         * set when the tree is flushing before a transaction commit,
 137         * used by the throttling code to decide if new updates need
 138         * to be run right away
 139         */
 140        int flushing;
 141
 142        u64 run_delayed_start;
 143};
 144
 145static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
 146{
 147        WARN_ON(atomic_read(&ref->refs) == 0);
 148        if (atomic_dec_and_test(&ref->refs)) {
 149                WARN_ON(ref->in_tree);
 150                kfree(ref);
 151        }
 152}
 153
 154int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
 155                               u64 bytenr, u64 num_bytes, u64 parent,
 156                               u64 ref_root, int level, int action,
 157                               struct btrfs_delayed_extent_op *extent_op);
 158int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
 159                               u64 bytenr, u64 num_bytes,
 160                               u64 parent, u64 ref_root,
 161                               u64 owner, u64 offset, int action,
 162                               struct btrfs_delayed_extent_op *extent_op);
 163int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans,
 164                                u64 bytenr, u64 num_bytes,
 165                                struct btrfs_delayed_extent_op *extent_op);
 166
 167struct btrfs_delayed_ref_head *
 168btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr);
 169int btrfs_delayed_ref_pending(struct btrfs_trans_handle *trans, u64 bytenr);
 170int btrfs_lookup_extent_info(struct btrfs_trans_handle *trans,
 171                             struct btrfs_root *root, u64 bytenr,
 172                             u64 num_bytes, u64 *refs, u64 *flags);
 173int btrfs_update_delayed_ref(struct btrfs_trans_handle *trans,
 174                          u64 bytenr, u64 num_bytes, u64 orig_parent,
 175                          u64 parent, u64 orig_ref_root, u64 ref_root,
 176                          u64 orig_ref_generation, u64 ref_generation,
 177                          u64 owner_objectid, int pin);
 178int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
 179                           struct btrfs_delayed_ref_head *head);
 180int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
 181                           struct list_head *cluster, u64 search_start);
 182/*
 183 * a node might live in a head or a regular ref, this lets you
 184 * test for the proper type to use.
 185 */
 186static int btrfs_delayed_ref_is_head(struct btrfs_delayed_ref_node *node)
 187{
 188        return node->is_head;
 189}
 190
 191/*
 192 * helper functions to cast a node into its container
 193 */
 194static inline struct btrfs_delayed_tree_ref *
 195btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node)
 196{
 197        WARN_ON(btrfs_delayed_ref_is_head(node));
 198        return container_of(node, struct btrfs_delayed_tree_ref, node);
 199}
 200
 201static inline struct btrfs_delayed_data_ref *
 202btrfs_delayed_node_to_data_ref(struct btrfs_delayed_ref_node *node)
 203{
 204        WARN_ON(btrfs_delayed_ref_is_head(node));
 205        return container_of(node, struct btrfs_delayed_data_ref, node);
 206}
 207
 208static inline struct btrfs_delayed_ref_head *
 209btrfs_delayed_node_to_head(struct btrfs_delayed_ref_node *node)
 210{
 211        WARN_ON(!btrfs_delayed_ref_is_head(node));
 212        return container_of(node, struct btrfs_delayed_ref_head, node);
 213}
 214#endif
 215