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#include <linux/refcount.h>
  22
  23/* these are the possible values of struct btrfs_delayed_ref_node->action */
  24#define BTRFS_ADD_DELAYED_REF    1 /* add one backref to the tree */
  25#define BTRFS_DROP_DELAYED_REF   2 /* delete one backref from the tree */
  26#define BTRFS_ADD_DELAYED_EXTENT 3 /* record a full extent allocation */
  27#define BTRFS_UPDATE_DELAYED_HEAD 4 /* not changing ref count on head ref */
  28
  29/*
  30 * XXX: Qu: I really hate the design that ref_head and tree/data ref shares the
  31 * same ref_node structure.
  32 * Ref_head is in a higher logic level than tree/data ref, and duplicated
  33 * bytenr/num_bytes in ref_node is really a waste or memory, they should be
  34 * referred from ref_head.
  35 * This gets more disgusting after we use list to store tree/data ref in
  36 * ref_head. Must clean this mess up later.
  37 */
  38struct btrfs_delayed_ref_node {
  39        /*data/tree ref use list, stored in ref_head->ref_list. */
  40        struct list_head list;
  41        /*
  42         * If action is BTRFS_ADD_DELAYED_REF, also link this node to
  43         * ref_head->ref_add_list, then we do not need to iterate the
  44         * whole ref_head->ref_list to find BTRFS_ADD_DELAYED_REF nodes.
  45         */
  46        struct list_head add_list;
  47
  48        /* the starting bytenr of the extent */
  49        u64 bytenr;
  50
  51        /* the size of the extent */
  52        u64 num_bytes;
  53
  54        /* seq number to keep track of insertion order */
  55        u64 seq;
  56
  57        /* ref count on this data structure */
  58        refcount_t refs;
  59
  60        /*
  61         * how many refs is this entry adding or deleting.  For
  62         * head refs, this may be a negative number because it is keeping
  63         * track of the total mods done to the reference count.
  64         * For individual refs, this will always be a positive number
  65         *
  66         * It may be more than one, since it is possible for a single
  67         * parent to have more than one ref on an extent
  68         */
  69        int ref_mod;
  70
  71        unsigned int action:8;
  72        unsigned int type:8;
  73        /* is this node still in the rbtree? */
  74        unsigned int is_head:1;
  75        unsigned int in_tree:1;
  76};
  77
  78struct btrfs_delayed_extent_op {
  79        struct btrfs_disk_key key;
  80        u8 level;
  81        bool update_key;
  82        bool update_flags;
  83        bool is_data;
  84        u64 flags_to_set;
  85};
  86
  87/*
  88 * the head refs are used to hold a lock on a given extent, which allows us
  89 * to make sure that only one process is running the delayed refs
  90 * at a time for a single extent.  They also store the sum of all the
  91 * reference count modifications we've queued up.
  92 */
  93struct btrfs_delayed_ref_head {
  94        struct btrfs_delayed_ref_node node;
  95
  96        /*
  97         * the mutex is held while running the refs, and it is also
  98         * held when checking the sum of reference modifications.
  99         */
 100        struct mutex mutex;
 101
 102        spinlock_t lock;
 103        struct list_head ref_list;
 104        /* accumulate add BTRFS_ADD_DELAYED_REF nodes to this ref_add_list. */
 105        struct list_head ref_add_list;
 106
 107        struct rb_node href_node;
 108
 109        struct btrfs_delayed_extent_op *extent_op;
 110
 111        /*
 112         * This is used to track the final ref_mod from all the refs associated
 113         * with this head ref, this is not adjusted as delayed refs are run,
 114         * this is meant to track if we need to do the csum accounting or not.
 115         */
 116        int total_ref_mod;
 117
 118        /*
 119         * For qgroup reserved space freeing.
 120         *
 121         * ref_root and reserved will be recorded after
 122         * BTRFS_ADD_DELAYED_EXTENT is called.
 123         * And will be used to free reserved qgroup space at
 124         * run_delayed_refs() time.
 125         */
 126        u64 qgroup_ref_root;
 127        u64 qgroup_reserved;
 128
 129        /*
 130         * when a new extent is allocated, it is just reserved in memory
 131         * The actual extent isn't inserted into the extent allocation tree
 132         * until the delayed ref is processed.  must_insert_reserved is
 133         * used to flag a delayed ref so the accounting can be updated
 134         * when a full insert is done.
 135         *
 136         * It is possible the extent will be freed before it is ever
 137         * inserted into the extent allocation tree.  In this case
 138         * we need to update the in ram accounting to properly reflect
 139         * the free has happened.
 140         */
 141        unsigned int must_insert_reserved:1;
 142        unsigned int is_data:1;
 143        unsigned int processing:1;
 144};
 145
 146struct btrfs_delayed_tree_ref {
 147        struct btrfs_delayed_ref_node node;
 148        u64 root;
 149        u64 parent;
 150        int level;
 151};
 152
 153struct btrfs_delayed_data_ref {
 154        struct btrfs_delayed_ref_node node;
 155        u64 root;
 156        u64 parent;
 157        u64 objectid;
 158        u64 offset;
 159};
 160
 161struct btrfs_delayed_ref_root {
 162        /* head ref rbtree */
 163        struct rb_root href_root;
 164
 165        /* dirty extent records */
 166        struct rb_root dirty_extent_root;
 167
 168        /* this spin lock protects the rbtree and the entries inside */
 169        spinlock_t lock;
 170
 171        /* how many delayed ref updates we've queued, used by the
 172         * throttling code
 173         */
 174        atomic_t num_entries;
 175
 176        /* total number of head nodes in tree */
 177        unsigned long num_heads;
 178
 179        /* total number of head nodes ready for processing */
 180        unsigned long num_heads_ready;
 181
 182        u64 pending_csums;
 183
 184        /*
 185         * set when the tree is flushing before a transaction commit,
 186         * used by the throttling code to decide if new updates need
 187         * to be run right away
 188         */
 189        int flushing;
 190
 191        u64 run_delayed_start;
 192
 193        /*
 194         * To make qgroup to skip given root.
 195         * This is for snapshot, as btrfs_qgroup_inherit() will manually
 196         * modify counters for snapshot and its source, so we should skip
 197         * the snapshot in new_root/old_roots or it will get calculated twice
 198         */
 199        u64 qgroup_to_skip;
 200};
 201
 202extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
 203extern struct kmem_cache *btrfs_delayed_tree_ref_cachep;
 204extern struct kmem_cache *btrfs_delayed_data_ref_cachep;
 205extern struct kmem_cache *btrfs_delayed_extent_op_cachep;
 206
 207int btrfs_delayed_ref_init(void);
 208void btrfs_delayed_ref_exit(void);
 209
 210static inline struct btrfs_delayed_extent_op *
 211btrfs_alloc_delayed_extent_op(void)
 212{
 213        return kmem_cache_alloc(btrfs_delayed_extent_op_cachep, GFP_NOFS);
 214}
 215
 216static inline void
 217btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op *op)
 218{
 219        if (op)
 220                kmem_cache_free(btrfs_delayed_extent_op_cachep, op);
 221}
 222
 223static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
 224{
 225        WARN_ON(refcount_read(&ref->refs) == 0);
 226        if (refcount_dec_and_test(&ref->refs)) {
 227                WARN_ON(ref->in_tree);
 228                switch (ref->type) {
 229                case BTRFS_TREE_BLOCK_REF_KEY:
 230                case BTRFS_SHARED_BLOCK_REF_KEY:
 231                        kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
 232                        break;
 233                case BTRFS_EXTENT_DATA_REF_KEY:
 234                case BTRFS_SHARED_DATA_REF_KEY:
 235                        kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
 236                        break;
 237                case 0:
 238                        kmem_cache_free(btrfs_delayed_ref_head_cachep, ref);
 239                        break;
 240                default:
 241                        BUG();
 242                }
 243        }
 244}
 245
 246int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
 247                               struct btrfs_trans_handle *trans,
 248                               u64 bytenr, u64 num_bytes, u64 parent,
 249                               u64 ref_root, int level, int action,
 250                               struct btrfs_delayed_extent_op *extent_op,
 251                               int *old_ref_mod, int *new_ref_mod);
 252int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
 253                               struct btrfs_trans_handle *trans,
 254                               u64 bytenr, u64 num_bytes,
 255                               u64 parent, u64 ref_root,
 256                               u64 owner, u64 offset, u64 reserved, int action,
 257                               int *old_ref_mod, int *new_ref_mod);
 258int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
 259                                struct btrfs_trans_handle *trans,
 260                                u64 bytenr, u64 num_bytes,
 261                                struct btrfs_delayed_extent_op *extent_op);
 262void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
 263                              struct btrfs_fs_info *fs_info,
 264                              struct btrfs_delayed_ref_root *delayed_refs,
 265                              struct btrfs_delayed_ref_head *head);
 266
 267struct btrfs_delayed_ref_head *
 268btrfs_find_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
 269                            u64 bytenr);
 270int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
 271                           struct btrfs_delayed_ref_head *head);
 272static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
 273{
 274        mutex_unlock(&head->mutex);
 275}
 276
 277
 278struct btrfs_delayed_ref_head *
 279btrfs_select_ref_head(struct btrfs_trans_handle *trans);
 280
 281int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info,
 282                            struct btrfs_delayed_ref_root *delayed_refs,
 283                            u64 seq);
 284
 285/*
 286 * a node might live in a head or a regular ref, this lets you
 287 * test for the proper type to use.
 288 */
 289static int btrfs_delayed_ref_is_head(struct btrfs_delayed_ref_node *node)
 290{
 291        return node->is_head;
 292}
 293
 294/*
 295 * helper functions to cast a node into its container
 296 */
 297static inline struct btrfs_delayed_tree_ref *
 298btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node)
 299{
 300        WARN_ON(btrfs_delayed_ref_is_head(node));
 301        return container_of(node, struct btrfs_delayed_tree_ref, node);
 302}
 303
 304static inline struct btrfs_delayed_data_ref *
 305btrfs_delayed_node_to_data_ref(struct btrfs_delayed_ref_node *node)
 306{
 307        WARN_ON(btrfs_delayed_ref_is_head(node));
 308        return container_of(node, struct btrfs_delayed_data_ref, node);
 309}
 310
 311static inline struct btrfs_delayed_ref_head *
 312btrfs_delayed_node_to_head(struct btrfs_delayed_ref_node *node)
 313{
 314        WARN_ON(!btrfs_delayed_ref_is_head(node));
 315        return container_of(node, struct btrfs_delayed_ref_head, node);
 316}
 317#endif
 318