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 parent our backref will point to */
  34         u64 parent;
  35
  36         /* the size of the extent */
  37         u64 num_bytes;
  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         /* is this node still in the rbtree? */
  54         unsigned int in_tree:1;
  55 };
  56
  57 /*
  58  * the head refs are used to hold a lock on a given extent, which allows us
  59  * to make sure that only one process is running the delayed refs
  60  * at a time for a single extent.  They also store the sum of all the
  61  * reference count modifications we've queued up.
  62  */
  63 struct btrfs_delayed_ref_head {
  64         struct btrfs_delayed_ref_node node;
  65
  66         /*
  67          * the mutex is held while running the refs, and it is also
  68          * held when checking the sum of reference modifications.
  69          */
  70         struct mutex mutex;
  71
  72         struct list_head cluster;
  73
  74         /*
  75          * when a new extent is allocated, it is just reserved in memory
  76          * The actual extent isn't inserted into the extent allocation tree
  77          * until the delayed ref is processed.  must_insert_reserved is
  78          * used to flag a delayed ref so the accounting can be updated
  79          * when a full insert is done.
  80          *
  81          * It is possible the extent will be freed before it is ever
  82          * inserted into the extent allocation tree.  In this case
  83          * we need to update the in ram accounting to properly reflect
  84          * the free has happened.
  85          */
  86         unsigned int must_insert_reserved:1;
  87 };
  88
  89 struct btrfs_delayed_ref {
  90         struct btrfs_delayed_ref_node node;
  91
  92         /* the root objectid our ref will point to */
  93         u64 root;
  94
  95         /* the generation for the backref */
  96         u64 generation;
  97
  98         /* owner_objectid of the backref  */
  99         u64 owner_objectid;
 100
 101         /* operation done by this entry in the rbtree */
 102         u8 action;
 103
 104         /* if pin == 1, when the extent is freed it will be pinned until
 105          * transaction commit
 106          */
 107         unsigned int pin:1;
 108 };
 109
 110 struct btrfs_delayed_ref_root {
 111         struct rb_root root;
 112
 113         /* this spin lock protects the rbtree and the entries inside */
 114         spinlock_t lock;
 115
 116         /* how many delayed ref updates we've queued, used by the
 117          * throttling code
 118          */
 119         unsigned long num_entries;
 120
 121         /* total number of head nodes in tree */
 122         unsigned long num_heads;
 123
 124         /* total number of head nodes ready for processing */
 125         unsigned long num_heads_ready;
 126
 127         /*
 128          * set when the tree is flushing before a transaction commit,
 129          * used by the throttling code to decide if new updates need
 130          * to be run right away
 131          */
 132         int flushing;
 133
 134         u64 run_delayed_start;
 135 };
 136
 137 static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
 138 {
 139         WARN_ON(atomic_read(&ref->refs) == 0);
 140         if (atomic_dec_and_test(&ref->refs)) {
 141                 WARN_ON(ref->in_tree);
 142                 kfree(ref);
 143         }
 144 }
 145
 146 int btrfs_add_delayed_ref(struct btrfs_trans_handle *trans,
 147                           u64 bytenr, u64 num_bytes, u64 parent, u64 ref_root,
 148                           u64 ref_generation, u64 owner_objectid, int action,
 149                           int pin);
 150
 151 struct btrfs_delayed_ref_head *
 152 btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr);
 153 int btrfs_delayed_ref_pending(struct btrfs_trans_handle *trans, u64 bytenr);
 154 int btrfs_lookup_extent_ref(struct btrfs_trans_handle *trans,
 155                             struct btrfs_root *root, u64 bytenr,
 156                             u64 num_bytes, u32 *refs);
 157 int btrfs_update_delayed_ref(struct btrfs_trans_handle *trans,
 158                           u64 bytenr, u64 num_bytes, u64 orig_parent,
 159                           u64 parent, u64 orig_ref_root, u64 ref_root,
 160                           u64 orig_ref_generation, u64 ref_generation,
 161                           u64 owner_objectid, int pin);
 162 int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
 163                            struct btrfs_delayed_ref_head *head);
 164 int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
 165                            struct list_head *cluster, u64 search_start);
 166 /*
 167  * a node might live in a head or a regular ref, this lets you
 168  * test for the proper type to use.
 169  */
 170 static int btrfs_delayed_ref_is_head(struct btrfs_delayed_ref_node *node)
 171 {
 172         return node->parent == (u64)-1;
 173 }
 174
 175 /*
 176  * helper functions to cast a node into its container
 177  */
 178 static inline struct btrfs_delayed_ref *
 179 btrfs_delayed_node_to_ref(struct btrfs_delayed_ref_node *node)
 180 {
 181         WARN_ON(btrfs_delayed_ref_is_head(node));
 182         return container_of(node, struct btrfs_delayed_ref, node);
 183
 184 }
 185
 186 static inline struct btrfs_delayed_ref_head *
 187 btrfs_delayed_node_to_head(struct btrfs_delayed_ref_node *node)
 188 {
 189         WARN_ON(!btrfs_delayed_ref_is_head(node));
 190         return container_of(node, struct btrfs_delayed_ref_head, node);
 191
 192 }
 193 #endif