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