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
  27 struct 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
  57 struct 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  */
  71 struct 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
  99 struct 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
 108 struct 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
 118 struct 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
 145 static 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
 154 int 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);
 158 int 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);
 163 int 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
 167 struct btrfs_delayed_ref_head *
 168 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr);
 169 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
 170                            struct btrfs_delayed_ref_head *head);
 171 int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
 172                            struct list_head *cluster, u64 search_start);
 173 /*
 174  * a node might live in a head or a regular ref, this lets you
 175  * test for the proper type to use.
 176  */
 177 static int btrfs_delayed_ref_is_head(struct btrfs_delayed_ref_node *node)
 178 {
 179         return node->is_head;
 180 }
 181
 182 /*
 183  * helper functions to cast a node into its container
 184  */
 185 static inline struct btrfs_delayed_tree_ref *
 186 btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node)
 187 {
 188         WARN_ON(btrfs_delayed_ref_is_head(node));
 189         return container_of(node, struct btrfs_delayed_tree_ref, node);
 190 }
 191
 192 static inline struct btrfs_delayed_data_ref *
 193 btrfs_delayed_node_to_data_ref(struct btrfs_delayed_ref_node *node)
 194 {
 195         WARN_ON(btrfs_delayed_ref_is_head(node));
 196         return container_of(node, struct btrfs_delayed_data_ref, node);
 197 }
 198
 199 static inline struct btrfs_delayed_ref_head *
 200 btrfs_delayed_node_to_head(struct btrfs_delayed_ref_node *node)
 201 {
 202         WARN_ON(!btrfs_delayed_ref_is_head(node));
 203         return container_of(node, struct btrfs_delayed_ref_head, node);
 204 }
 205 #endif