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                 list_del_init(&transaction->list);
  23                 memset(transaction, 0, sizeof(*transaction));
  24                 kmem_cache_free(btrfs_transaction_cachep, transaction);
  25         }
  26 }
  27
  28 static int join_transaction(struct btrfs_root *root)
  29 {
  30         struct btrfs_transaction *cur_trans;
  31         cur_trans = root->fs_info->running_transaction;
  32         if (!cur_trans) {
  33                 cur_trans = kmem_cache_alloc(btrfs_transaction_cachep,
  34                                              GFP_NOFS);
  35                 total_trans++;
  36                 BUG_ON(!cur_trans);
  37                 root->fs_info->generation++;
  38                 root->fs_info->running_transaction = cur_trans;
  39                 cur_trans->num_writers = 0;
  40                 cur_trans->transid = root->fs_info->generation;
  41                 init_waitqueue_head(&cur_trans->writer_wait);
  42                 init_waitqueue_head(&cur_trans->commit_wait);
  43                 cur_trans->magic = TRANS_MAGIC;
  44                 cur_trans->in_commit = 0;
  45                 cur_trans->use_count = 1;
  46                 cur_trans->commit_done = 0;
  47                 list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
  48         }
  49         cur_trans->num_writers++;
  50         return 0;
  51 }
  52
  53 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
  54                                                    int num_blocks)
  55 {
  56         struct btrfs_trans_handle *h =
  57                 kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
  58         int ret;
  59         u64 running_trans_id;
  60
  61         mutex_lock(&root->fs_info->trans_mutex);
  62         ret = join_transaction(root);
  63         BUG_ON(ret);
  64         running_trans_id = root->fs_info->running_transaction->transid;
  65
  66         if (root != root->fs_info->tree_root && root->last_trans <
  67             running_trans_id) {
  68                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
  69                                    (unsigned long)root->root_key.objectid,
  70                                    BTRFS_ROOT_TRANS_TAG);
  71                 root->commit_root = root->node;
  72                 get_bh(root->node);
  73         }
  74         root->last_trans = running_trans_id;
  75         h->transid = running_trans_id;
  76         h->transaction = root->fs_info->running_transaction;
  77         h->blocks_reserved = num_blocks;
  78         h->blocks_used = 0;
  79         root->fs_info->running_transaction->use_count++;
  80         mutex_unlock(&root->fs_info->trans_mutex);
  81         h->magic = h->magic2 = TRANS_MAGIC;
  82         return h;
  83 }
  84
  85 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
  86                           struct btrfs_root *root)
  87 {
  88         struct btrfs_transaction *cur_trans;
  89
  90         WARN_ON(trans->magic != TRANS_MAGIC);
  91         WARN_ON(trans->magic2 != TRANS_MAGIC);
  92         mutex_lock(&root->fs_info->trans_mutex);
  93         cur_trans = root->fs_info->running_transaction;
  94         WARN_ON(cur_trans->num_writers < 1);
  95         if (waitqueue_active(&cur_trans->writer_wait))
  96                 wake_up(&cur_trans->writer_wait);
  97         cur_trans->num_writers--;
  98         put_transaction(cur_trans);
  99         mutex_unlock(&root->fs_info->trans_mutex);
 100         memset(trans, 0, sizeof(*trans));
 101         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 102         return 0;
 103 }
 104
 105
 106 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 107                                      struct btrfs_root *root)
 108 {
 109         filemap_write_and_wait(root->fs_info->btree_inode->i_mapping);
 110         return 0;
 111 }
 112
 113 int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
 114                             struct btrfs_root *root)
 115 {
 116         int ret;
 117         u64 old_extent_block;
 118         struct btrfs_fs_info *fs_info = root->fs_info;
 119         struct btrfs_root *tree_root = fs_info->tree_root;
 120         struct btrfs_root *extent_root = fs_info->extent_root;
 121         struct btrfs_root *dev_root = fs_info->dev_root;
 122
 123         if (btrfs_super_device_root(fs_info->disk_super) !=
 124             bh_blocknr(dev_root->node)) {
 125                 btrfs_set_super_device_root(fs_info->disk_super,
 126                                             bh_blocknr(dev_root->node));
 127         }
 128         btrfs_write_dirty_block_groups(trans, extent_root);
 129         while(1) {
 130                 old_extent_block = btrfs_root_blocknr(&extent_root->root_item);
 131                 if (old_extent_block == bh_blocknr(extent_root->node))
 132                         break;
 133                 btrfs_set_root_blocknr(&extent_root->root_item,
 134                                        bh_blocknr(extent_root->node));
 135                 ret = btrfs_update_root(trans, tree_root,
 136                                         &extent_root->root_key,
 137                                         &extent_root->root_item);
 138                 BUG_ON(ret);
 139                 btrfs_write_dirty_block_groups(trans, extent_root);
 140         }
 141         return 0;
 142 }
 143
 144 static int wait_for_commit(struct btrfs_root *root,
 145                            struct btrfs_transaction *commit)
 146 {
 147         DEFINE_WAIT(wait);
 148         while(!commit->commit_done) {
 149                 prepare_to_wait(&commit->commit_wait, &wait,
 150                                 TASK_UNINTERRUPTIBLE);
 151                 if (commit->commit_done)
 152                         break;
 153                 mutex_unlock(&root->fs_info->trans_mutex);
 154                 schedule();
 155                 mutex_lock(&root->fs_info->trans_mutex);
 156         }
 157         finish_wait(&commit->commit_wait, &wait);
 158         return 0;
 159 }
 160
 161 struct dirty_root {
 162         struct list_head list;
 163         struct btrfs_key snap_key;
 164         struct buffer_head *commit_root;
 165         struct btrfs_root *root;
 166 };
 167
 168 int add_dirty_roots(struct btrfs_trans_handle *trans,
 169                     struct radix_tree_root *radix, struct list_head *list)
 170 {
 171         struct dirty_root *dirty;
 172         struct btrfs_root *gang[8];
 173         struct btrfs_root *root;
 174         int i;
 175         int ret;
 176         int err;
 177         while(1) {
 178                 ret = radix_tree_gang_lookup_tag(radix, (void **)gang, 0,
 179                                                  ARRAY_SIZE(gang),
 180                                                  BTRFS_ROOT_TRANS_TAG);
 181                 if (ret == 0)
 182                         break;
 183                 for (i = 0; i < ret; i++) {
 184                         root = gang[i];
 185                         radix_tree_tag_clear(radix,
 186                                      (unsigned long)root->root_key.objectid,
 187                                      BTRFS_ROOT_TRANS_TAG);
 188                         if (root->commit_root == root->node) {
 189                                 WARN_ON(bh_blocknr(root->node) !=
 190                                         btrfs_root_blocknr(&root->root_item));
 191                                 brelse(root->commit_root);
 192                                 root->commit_root = NULL;
 193                                 continue;
 194                         }
 195                         dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
 196                         BUG_ON(!dirty);
 197                         memcpy(&dirty->snap_key, &root->root_key,
 198                                sizeof(root->root_key));
 199                         dirty->commit_root = root->commit_root;
 200                         root->commit_root = NULL;
 201                         dirty->root = root;
 202                         root->root_key.offset = root->fs_info->generation;
 203                         btrfs_set_root_blocknr(&root->root_item,
 204                                                bh_blocknr(root->node));
 205                         err = btrfs_insert_root(trans, root->fs_info->tree_root,
 206                                                 &root->root_key,
 207                                                 &root->root_item);
 208                         BUG_ON(err);
 209                         list_add(&dirty->list, list);
 210                 }
 211         }
 212         return 0;
 213 }
 214
 215 int drop_dirty_roots(struct btrfs_root *tree_root, struct list_head *list)
 216 {
 217         struct dirty_root *dirty;
 218         struct btrfs_trans_handle *trans;
 219         int ret;
 220
 221         while(!list_empty(list)) {
 222                 dirty = list_entry(list->next, struct dirty_root, list);
 223                 list_del_init(&dirty->list);
 224                 trans = btrfs_start_transaction(tree_root, 1);
 225                 ret = btrfs_drop_snapshot(trans, dirty->root,
 226                                           dirty->commit_root);
 227                 BUG_ON(ret);
 228
 229                 ret = btrfs_del_root(trans, tree_root, &dirty->snap_key);
 230                 BUG_ON(ret);
 231                 ret = btrfs_end_transaction(trans, tree_root);
 232                 BUG_ON(ret);
 233                 kfree(dirty);
 234         }
 235         return 0;
 236 }
 237
 238 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 239                              struct btrfs_root *root)
 240 {
 241         int ret = 0;
 242         struct btrfs_transaction *cur_trans;
 243         struct btrfs_transaction *prev_trans = NULL;
 244         struct list_head dirty_fs_roots;
 245         DEFINE_WAIT(wait);
 246
 247         INIT_LIST_HEAD(&dirty_fs_roots);
 248
 249         mutex_lock(&root->fs_info->trans_mutex);
 250         if (trans->transaction->in_commit) {
 251                 cur_trans = trans->transaction;
 252                 trans->transaction->use_count++;
 253                 btrfs_end_transaction(trans, root);
 254                 ret = wait_for_commit(root, cur_trans);
 255                 BUG_ON(ret);
 256                 put_transaction(cur_trans);
 257                 mutex_unlock(&root->fs_info->trans_mutex);
 258                 return 0;
 259         }
 260         cur_trans = trans->transaction;
 261         trans->transaction->in_commit = 1;
 262         while (trans->transaction->num_writers > 1) {
 263                 WARN_ON(cur_trans != trans->transaction);
 264                 prepare_to_wait(&trans->transaction->writer_wait, &wait,
 265                                 TASK_UNINTERRUPTIBLE);
 266                 if (trans->transaction->num_writers <= 1)
 267                         break;
 268                 mutex_unlock(&root->fs_info->trans_mutex);
 269                 schedule();
 270                 mutex_lock(&root->fs_info->trans_mutex);
 271                 finish_wait(&trans->transaction->writer_wait, &wait);
 272         }
 273         finish_wait(&trans->transaction->writer_wait, &wait);
 274         WARN_ON(cur_trans != trans->transaction);
 275         add_dirty_roots(trans, &root->fs_info->fs_roots_radix, &dirty_fs_roots);
 276         ret = btrfs_commit_tree_roots(trans, root);
 277         BUG_ON(ret);
 278         cur_trans = root->fs_info->running_transaction;
 279         root->fs_info->running_transaction = NULL;
 280         if (cur_trans->list.prev != &root->fs_info->trans_list) {
 281                 prev_trans = list_entry(cur_trans->list.prev,
 282                                         struct btrfs_transaction, list);
 283                 if (prev_trans->commit_done)
 284                         prev_trans = NULL;
 285                 else
 286                         prev_trans->use_count++;
 287         }
 288         mutex_unlock(&root->fs_info->trans_mutex);
 289         mutex_unlock(&root->fs_info->fs_mutex);
 290         ret = btrfs_write_and_wait_transaction(trans, root);
 291         if (prev_trans) {
 292                 mutex_lock(&root->fs_info->trans_mutex);
 293                 wait_for_commit(root, prev_trans);
 294                 put_transaction(prev_trans);
 295                 mutex_unlock(&root->fs_info->trans_mutex);
 296         }
 297         btrfs_set_super_generation(root->fs_info->disk_super,
 298                                    cur_trans->transid);
 299         BUG_ON(ret);
 300         write_ctree_super(trans, root);
 301
 302         mutex_lock(&root->fs_info->fs_mutex);
 303         btrfs_finish_extent_commit(trans, root);
 304         mutex_lock(&root->fs_info->trans_mutex);
 305         cur_trans->commit_done = 1;
 306         wake_up(&cur_trans->commit_wait);
 307         put_transaction(cur_trans);
 308         put_transaction(cur_trans);
 309         mutex_unlock(&root->fs_info->trans_mutex);
 310         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 311
 312         drop_dirty_roots(root->fs_info->tree_root, &dirty_fs_roots);
 313         return ret;
 314 }
 315