fs/btrfs/transaction.c

   1 #include <linux/module.h>
   2 #include <linux/fs.h>
   3 #include "ctree.h"
   4 #include "disk-io.h"
   5 #include "transaction.h"
   6
   7 static int total_trans = 0;
   8 extern struct kmem_cache *btrfs_trans_handle_cachep;
   9 extern struct kmem_cache *btrfs_transaction_cachep;
  10
  11 #define BTRFS_ROOT_TRANS_TAG 0
  12
  13 #define TRANS_MAGIC 0xE1E10E
  14 static void put_transaction(struct btrfs_transaction *transaction)
  15 {
  16         WARN_ON(transaction->use_count == 0);
  17         transaction->use_count--;
  18         WARN_ON(transaction->magic != TRANS_MAGIC);
  19         if (transaction->use_count == 0) {
  20                 WARN_ON(total_trans == 0);
  21                 total_trans--;
  22                 memset(transaction, 0, sizeof(*transaction));
  23                 kmem_cache_free(btrfs_transaction_cachep, transaction);
  24         }
  25 }
  26
  27 static int join_transaction(struct btrfs_root *root)
  28 {
  29         struct btrfs_transaction *cur_trans;
  30         cur_trans = root->fs_info->running_transaction;
  31         if (!cur_trans) {
  32                 cur_trans = kmem_cache_alloc(btrfs_transaction_cachep,
  33                                              GFP_NOFS);
  34                 total_trans++;
  35                 BUG_ON(!cur_trans);
  36                 root->fs_info->generation++;
  37                 root->fs_info->running_transaction = cur_trans;
  38                 cur_trans->num_writers = 0;
  39                 cur_trans->transid = root->fs_info->generation;
  40                 init_waitqueue_head(&cur_trans->writer_wait);
  41                 init_waitqueue_head(&cur_trans->commit_wait);
  42                 cur_trans->magic = TRANS_MAGIC;
  43                 cur_trans->in_commit = 0;
  44                 cur_trans->use_count = 1;
  45                 cur_trans->commit_done = 0;
  46         }
  47         cur_trans->num_writers++;
  48         return 0;
  49 }
  50
  51 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
  52                                                    int num_blocks)
  53 {
  54         struct btrfs_trans_handle *h =
  55                 kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
  56         int ret;
  57         u64 running_trans_id;
  58
  59         mutex_lock(&root->fs_info->trans_mutex);
  60         ret = join_transaction(root);
  61         BUG_ON(ret);
  62         running_trans_id = root->fs_info->running_transaction->transid;
  63
  64         if (root != root->fs_info->tree_root && root->last_trans <
  65             running_trans_id) {
  66                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
  67                                    (unsigned long)root->root_key.objectid,
  68                                    BTRFS_ROOT_TRANS_TAG);
  69                 root->commit_root = root->node;
  70                 get_bh(root->node);
  71         }
  72         root->last_trans = running_trans_id;
  73         h->transid = running_trans_id;
  74         h->transaction = root->fs_info->running_transaction;
  75         h->blocks_reserved = num_blocks;
  76         h->blocks_used = 0;
  77         root->fs_info->running_transaction->use_count++;
  78         mutex_unlock(&root->fs_info->trans_mutex);
  79         h->magic = h->magic2 = TRANS_MAGIC;
  80         return h;
  81 }
  82
  83 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
  84                           struct btrfs_root *root)
  85 {
  86         struct btrfs_transaction *cur_trans;
  87
  88         WARN_ON(trans->magic != TRANS_MAGIC);
  89         WARN_ON(trans->magic2 != TRANS_MAGIC);
  90         mutex_lock(&root->fs_info->trans_mutex);
  91         cur_trans = root->fs_info->running_transaction;
  92         WARN_ON(cur_trans->num_writers < 1);
  93         if (waitqueue_active(&cur_trans->writer_wait))
  94                 wake_up(&cur_trans->writer_wait);
  95         cur_trans->num_writers--;
  96         put_transaction(cur_trans);
  97         mutex_unlock(&root->fs_info->trans_mutex);
  98         memset(trans, 0, sizeof(*trans));
  99         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 100         return 0;
 101 }
 102
 103
 104 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 105                                      struct btrfs_root *root)
 106 {
 107         filemap_write_and_wait(root->fs_info->btree_inode->i_mapping);
 108         return 0;
 109 }
 110
 111 int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
 112                             struct btrfs_root *root)
 113 {
 114         int ret;
 115         u64 old_extent_block;
 116         struct btrfs_fs_info *fs_info = root->fs_info;
 117         struct btrfs_root *tree_root = fs_info->tree_root;
 118         struct btrfs_root *extent_root = fs_info->extent_root;
 119         struct btrfs_root *dev_root = fs_info->dev_root;
 120
 121         if (btrfs_super_device_root(fs_info->disk_super) !=
 122             bh_blocknr(dev_root->node)) {
 123                 btrfs_set_super_device_root(fs_info->disk_super,
 124                                             bh_blocknr(dev_root->node));
 125         }
 126         while(1) {
 127                 old_extent_block = btrfs_root_blocknr(&extent_root->root_item);
 128                 if (old_extent_block == bh_blocknr(extent_root->node))
 129                         break;
 130                 btrfs_set_root_blocknr(&extent_root->root_item,
 131                                        bh_blocknr(extent_root->node));
 132                 ret = btrfs_update_root(trans, tree_root,
 133                                         &extent_root->root_key,
 134                                         &extent_root->root_item);
 135                 BUG_ON(ret);
 136         }
 137         return 0;
 138 }
 139
 140 static int wait_for_commit(struct btrfs_root *root,
 141                            struct btrfs_transaction *commit)
 142 {
 143         DEFINE_WAIT(wait);
 144         while(!commit->commit_done) {
 145                 prepare_to_wait(&commit->commit_wait, &wait,
 146                                 TASK_UNINTERRUPTIBLE);
 147                 if (commit->commit_done)
 148                         break;
 149                 mutex_unlock(&root->fs_info->trans_mutex);
 150                 schedule();
 151                 mutex_lock(&root->fs_info->trans_mutex);
 152         }
 153         finish_wait(&commit->commit_wait, &wait);
 154         return 0;
 155 }
 156
 157 struct dirty_root {
 158         struct list_head list;
 159         struct btrfs_key snap_key;
 160         struct buffer_head *commit_root;
 161         struct btrfs_root *root;
 162 };
 163
 164 int add_dirty_roots(struct btrfs_trans_handle *trans,
 165                     struct radix_tree_root *radix, struct list_head *list)
 166 {
 167         struct dirty_root *dirty;
 168         struct btrfs_root *gang[8];
 169         struct btrfs_root *root;
 170         int i;
 171         int ret;
 172         int err;
 173         while(1) {
 174                 ret = radix_tree_gang_lookup_tag(radix, (void **)gang, 0,
 175                                                  ARRAY_SIZE(gang),
 176                                                  BTRFS_ROOT_TRANS_TAG);
 177                 if (ret == 0)
 178                         break;
 179                 for (i = 0; i < ret; i++) {
 180                         root = gang[i];
 181                         radix_tree_tag_clear(radix,
 182                                      (unsigned long)root->root_key.objectid,
 183                                      BTRFS_ROOT_TRANS_TAG);
 184                         if (root->commit_root == root->node) {
 185                                 WARN_ON(bh_blocknr(root->node) !=
 186                                         btrfs_root_blocknr(&root->root_item));
 187                                 brelse(root->commit_root);
 188                                 root->commit_root = NULL;
 189                                 continue;
 190                         }
 191                         dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
 192                         BUG_ON(!dirty);
 193                         memcpy(&dirty->snap_key, &root->root_key,
 194                                sizeof(root->root_key));
 195                         dirty->commit_root = root->commit_root;
 196                         root->commit_root = NULL;
 197                         dirty->root = root;
 198                         root->root_key.offset = root->fs_info->generation;
 199                         btrfs_set_root_blocknr(&root->root_item,
 200                                                bh_blocknr(root->node));
 201                         err = btrfs_insert_root(trans, root->fs_info->tree_root,
 202                                                 &root->root_key,
 203                                                 &root->root_item);
 204                         BUG_ON(err);
 205                         list_add(&dirty->list, list);
 206                 }
 207         }
 208         return 0;
 209 }
 210
 211 int drop_dirty_roots(struct btrfs_root *tree_root, struct list_head *list)
 212 {
 213         struct dirty_root *dirty;
 214         struct btrfs_trans_handle *trans;
 215         int ret;
 216
 217         while(!list_empty(list)) {
 218                 dirty = list_entry(list->next, struct dirty_root, list);
 219                 list_del_init(&dirty->list);
 220                 trans = btrfs_start_transaction(tree_root, 1);
 221                 ret = btrfs_drop_snapshot(trans, dirty->root,
 222                                           dirty->commit_root);
 223                 BUG_ON(ret);
 224
 225                 ret = btrfs_del_root(trans, tree_root, &dirty->snap_key);
 226                 BUG_ON(ret);
 227                 ret = btrfs_end_transaction(trans, tree_root);
 228                 BUG_ON(ret);
 229                 kfree(dirty);
 230         }
 231         return 0;
 232 }
 233
 234 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 235                              struct btrfs_root *root)
 236 {
 237         int ret = 0;
 238         struct btrfs_transaction *cur_trans;
 239         struct list_head dirty_fs_roots;
 240         DEFINE_WAIT(wait);
 241
 242         INIT_LIST_HEAD(&dirty_fs_roots);
 243
 244         mutex_lock(&root->fs_info->trans_mutex);
 245         if (trans->transaction->in_commit) {
 246                 cur_trans = trans->transaction;
 247                 trans->transaction->use_count++;
 248                 btrfs_end_transaction(trans, root);
 249                 ret = wait_for_commit(root, cur_trans);
 250                 BUG_ON(ret);
 251                 put_transaction(cur_trans);
 252                 mutex_unlock(&root->fs_info->trans_mutex);
 253                 return 0;
 254         }
 255         cur_trans = trans->transaction;
 256         trans->transaction->in_commit = 1;
 257         while (trans->transaction->num_writers > 1) {
 258                 WARN_ON(cur_trans != trans->transaction);
 259                 prepare_to_wait(&trans->transaction->writer_wait, &wait,
 260                                 TASK_UNINTERRUPTIBLE);
 261                 if (trans->transaction->num_writers <= 1)
 262                         break;
 263                 mutex_unlock(&root->fs_info->trans_mutex);
 264                 schedule();
 265                 mutex_lock(&root->fs_info->trans_mutex);
 266                 finish_wait(&trans->transaction->writer_wait, &wait);
 267         }
 268         finish_wait(&trans->transaction->writer_wait, &wait);
 269         WARN_ON(cur_trans != trans->transaction);
 270         add_dirty_roots(trans, &root->fs_info->fs_roots_radix, &dirty_fs_roots);
 271         ret = btrfs_commit_tree_roots(trans, root);
 272         BUG_ON(ret);
 273         cur_trans = root->fs_info->running_transaction;
 274         root->fs_info->running_transaction = NULL;
 275         btrfs_set_super_generation(root->fs_info->disk_super,
 276                                    root->fs_info->generation + 1);
 277         mutex_unlock(&root->fs_info->trans_mutex);
 278         ret = btrfs_write_and_wait_transaction(trans, root);
 279         BUG_ON(ret);
 280
 281         write_ctree_super(trans, root);
 282         btrfs_finish_extent_commit(trans, root);
 283         mutex_lock(&root->fs_info->trans_mutex);
 284         cur_trans->commit_done = 1;
 285         wake_up(&cur_trans->commit_wait);
 286         put_transaction(cur_trans);
 287         put_transaction(cur_trans);
 288         mutex_unlock(&root->fs_info->trans_mutex);
 289         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 290
 291         drop_dirty_roots(root->fs_info->tree_root, &dirty_fs_roots);
 292         return ret;
 293 }
 294