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                 init_bit_radix(&cur_trans->dirty_pages);
  49         }
  50         cur_trans->num_writers++;
  51         return 0;
  52 }
  53
  54 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
  55                                                    int num_blocks)
  56 {
  57         struct btrfs_trans_handle *h =
  58                 kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
  59         int ret;
  60         u64 running_trans_id;
  61
  62         mutex_lock(&root->fs_info->trans_mutex);
  63         ret = join_transaction(root);
  64         BUG_ON(ret);
  65         running_trans_id = root->fs_info->running_transaction->transid;
  66
  67         if (root != root->fs_info->tree_root && root->last_trans <
  68             running_trans_id) {
  69                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
  70                                    (unsigned long)root->root_key.objectid,
  71                                    BTRFS_ROOT_TRANS_TAG);
  72                 root->commit_root = root->node;
  73                 get_bh(root->node);
  74         }
  75         root->last_trans = running_trans_id;
  76         h->transid = running_trans_id;
  77         h->transaction = root->fs_info->running_transaction;
  78         h->blocks_reserved = num_blocks;
  79         h->blocks_used = 0;
  80         h->block_group = NULL;
  81         root->fs_info->running_transaction->use_count++;
  82         mutex_unlock(&root->fs_info->trans_mutex);
  83         h->magic = h->magic2 = TRANS_MAGIC;
  84         return h;
  85 }
  86
  87 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
  88                           struct btrfs_root *root)
  89 {
  90         struct btrfs_transaction *cur_trans;
  91
  92         WARN_ON(trans->magic != TRANS_MAGIC);
  93         WARN_ON(trans->magic2 != TRANS_MAGIC);
  94         mutex_lock(&root->fs_info->trans_mutex);
  95         cur_trans = root->fs_info->running_transaction;
  96         WARN_ON(cur_trans->num_writers < 1);
  97         if (waitqueue_active(&cur_trans->writer_wait))
  98                 wake_up(&cur_trans->writer_wait);
  99         cur_trans->num_writers--;
 100         put_transaction(cur_trans);
 101         mutex_unlock(&root->fs_info->trans_mutex);
 102         memset(trans, 0, sizeof(*trans));
 103         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 104         return 0;
 105 }
 106
 107
 108 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 109                                      struct btrfs_root *root)
 110 {
 111         unsigned long gang[16];
 112         int ret;
 113         int i;
 114         int err;
 115         int werr = 0;
 116         struct page *page;
 117         struct radix_tree_root *dirty_pages;
 118         struct inode *btree_inode = root->fs_info->btree_inode;
 119
 120         if (!trans || !trans->transaction) {
 121                 return filemap_write_and_wait(btree_inode->i_mapping);
 122         }
 123         dirty_pages = &trans->transaction->dirty_pages;
 124         while(1) {
 125                 ret = find_first_radix_bit(dirty_pages, gang,
 126                                            0, ARRAY_SIZE(gang));
 127                 if (!ret)
 128                         break;
 129                 for (i = 0; i < ret; i++) {
 130                         /* FIXME EIO */
 131                         clear_radix_bit(dirty_pages, gang[i]);
 132                         page = find_lock_page(btree_inode->i_mapping,
 133                                               gang[i]);
 134                         if (!page)
 135                                 continue;
 136                         err = write_one_page(page, 0);
 137                         if (err)
 138                                 werr = err;
 139                         page_cache_release(page);
 140                 }
 141         }
 142         err = filemap_fdatawait(btree_inode->i_mapping);
 143         if (err)
 144                 werr = err;
 145         return werr;
 146 }
 147
 148 int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
 149                             struct btrfs_root *root)
 150 {
 151         int ret;
 152         u64 old_extent_block;
 153         struct btrfs_fs_info *fs_info = root->fs_info;
 154         struct btrfs_root *tree_root = fs_info->tree_root;
 155         struct btrfs_root *extent_root = fs_info->extent_root;
 156         struct btrfs_root *dev_root = fs_info->dev_root;
 157
 158         if (btrfs_super_device_root(fs_info->disk_super) !=
 159             bh_blocknr(dev_root->node)) {
 160                 btrfs_set_super_device_root(fs_info->disk_super,
 161                                             bh_blocknr(dev_root->node));
 162         }
 163         btrfs_write_dirty_block_groups(trans, extent_root);
 164         while(1) {
 165                 old_extent_block = btrfs_root_blocknr(&extent_root->root_item);
 166                 if (old_extent_block == bh_blocknr(extent_root->node))
 167                         break;
 168                 btrfs_set_root_blocknr(&extent_root->root_item,
 169                                        bh_blocknr(extent_root->node));
 170                 ret = btrfs_update_root(trans, tree_root,
 171                                         &extent_root->root_key,
 172                                         &extent_root->root_item);
 173                 BUG_ON(ret);
 174                 btrfs_write_dirty_block_groups(trans, extent_root);
 175         }
 176         return 0;
 177 }
 178
 179 static int wait_for_commit(struct btrfs_root *root,
 180                            struct btrfs_transaction *commit)
 181 {
 182         DEFINE_WAIT(wait);
 183         while(!commit->commit_done) {
 184                 prepare_to_wait(&commit->commit_wait, &wait,
 185                                 TASK_UNINTERRUPTIBLE);
 186                 if (commit->commit_done)
 187                         break;
 188                 mutex_unlock(&root->fs_info->trans_mutex);
 189                 schedule();
 190                 mutex_lock(&root->fs_info->trans_mutex);
 191         }
 192         finish_wait(&commit->commit_wait, &wait);
 193         return 0;
 194 }
 195
 196 struct dirty_root {
 197         struct list_head list;
 198         struct btrfs_key snap_key;
 199         struct buffer_head *commit_root;
 200         struct btrfs_root *root;
 201 };
 202
 203 static int add_dirty_roots(struct btrfs_trans_handle *trans,
 204                            struct radix_tree_root *radix,
 205                            struct list_head *list)
 206 {
 207         struct dirty_root *dirty;
 208         struct btrfs_root *gang[8];
 209         struct btrfs_root *root;
 210         int i;
 211         int ret;
 212         int err;
 213         while(1) {
 214                 ret = radix_tree_gang_lookup_tag(radix, (void **)gang, 0,
 215                                                  ARRAY_SIZE(gang),
 216                                                  BTRFS_ROOT_TRANS_TAG);
 217                 if (ret == 0)
 218                         break;
 219                 for (i = 0; i < ret; i++) {
 220                         root = gang[i];
 221                         radix_tree_tag_clear(radix,
 222                                      (unsigned long)root->root_key.objectid,
 223                                      BTRFS_ROOT_TRANS_TAG);
 224                         if (root->commit_root == root->node) {
 225                                 WARN_ON(bh_blocknr(root->node) !=
 226                                         btrfs_root_blocknr(&root->root_item));
 227                                 brelse(root->commit_root);
 228                                 root->commit_root = NULL;
 229                                 continue;
 230                         }
 231                         dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
 232                         BUG_ON(!dirty);
 233                         memcpy(&dirty->snap_key, &root->root_key,
 234                                sizeof(root->root_key));
 235                         dirty->commit_root = root->commit_root;
 236                         root->commit_root = NULL;
 237                         dirty->root = root;
 238                         root->root_key.offset = root->fs_info->generation;
 239                         btrfs_set_root_blocknr(&root->root_item,
 240                                                bh_blocknr(root->node));
 241                         err = btrfs_insert_root(trans, root->fs_info->tree_root,
 242                                                 &root->root_key,
 243                                                 &root->root_item);
 244                         BUG_ON(err);
 245                         list_add(&dirty->list, list);
 246                 }
 247         }
 248         return 0;
 249 }
 250
 251 static int drop_dirty_roots(struct btrfs_root *tree_root,
 252                             struct list_head *list)
 253 {
 254         struct dirty_root *dirty;
 255         struct btrfs_trans_handle *trans;
 256         int ret;
 257
 258         while(!list_empty(list)) {
 259                 dirty = list_entry(list->next, struct dirty_root, list);
 260                 list_del_init(&dirty->list);
 261                 trans = btrfs_start_transaction(tree_root, 1);
 262                 ret = btrfs_drop_snapshot(trans, dirty->root,
 263                                           dirty->commit_root);
 264                 BUG_ON(ret);
 265
 266                 ret = btrfs_del_root(trans, tree_root, &dirty->snap_key);
 267                 BUG_ON(ret);
 268                 ret = btrfs_end_transaction(trans, tree_root);
 269                 BUG_ON(ret);
 270                 kfree(dirty);
 271         }
 272         return 0;
 273 }
 274
 275 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 276                              struct btrfs_root *root)
 277 {
 278         int ret = 0;
 279         struct btrfs_transaction *cur_trans;
 280         struct btrfs_transaction *prev_trans = NULL;
 281         struct list_head dirty_fs_roots;
 282         DEFINE_WAIT(wait);
 283
 284         INIT_LIST_HEAD(&dirty_fs_roots);
 285
 286         mutex_lock(&root->fs_info->trans_mutex);
 287         if (trans->transaction->in_commit) {
 288                 cur_trans = trans->transaction;
 289                 trans->transaction->use_count++;
 290                 btrfs_end_transaction(trans, root);
 291                 ret = wait_for_commit(root, cur_trans);
 292                 BUG_ON(ret);
 293                 put_transaction(cur_trans);
 294                 mutex_unlock(&root->fs_info->trans_mutex);
 295                 return 0;
 296         }
 297         cur_trans = trans->transaction;
 298         trans->transaction->in_commit = 1;
 299         while (trans->transaction->num_writers > 1) {
 300                 WARN_ON(cur_trans != trans->transaction);
 301                 prepare_to_wait(&trans->transaction->writer_wait, &wait,
 302                                 TASK_UNINTERRUPTIBLE);
 303                 if (trans->transaction->num_writers <= 1)
 304                         break;
 305                 mutex_unlock(&root->fs_info->trans_mutex);
 306                 schedule();
 307                 mutex_lock(&root->fs_info->trans_mutex);
 308                 finish_wait(&trans->transaction->writer_wait, &wait);
 309         }
 310         finish_wait(&trans->transaction->writer_wait, &wait);
 311         WARN_ON(cur_trans != trans->transaction);
 312         add_dirty_roots(trans, &root->fs_info->fs_roots_radix, &dirty_fs_roots);
 313         ret = btrfs_commit_tree_roots(trans, root);
 314         BUG_ON(ret);
 315         cur_trans = root->fs_info->running_transaction;
 316         root->fs_info->running_transaction = NULL;
 317         if (cur_trans->list.prev != &root->fs_info->trans_list) {
 318                 prev_trans = list_entry(cur_trans->list.prev,
 319                                         struct btrfs_transaction, list);
 320                 if (prev_trans->commit_done)
 321                         prev_trans = NULL;
 322                 else
 323                         prev_trans->use_count++;
 324         }
 325         mutex_unlock(&root->fs_info->trans_mutex);
 326         mutex_unlock(&root->fs_info->fs_mutex);
 327         ret = btrfs_write_and_wait_transaction(trans, root);
 328         if (prev_trans) {
 329                 mutex_lock(&root->fs_info->trans_mutex);
 330                 wait_for_commit(root, prev_trans);
 331                 put_transaction(prev_trans);
 332                 mutex_unlock(&root->fs_info->trans_mutex);
 333         }
 334         btrfs_set_super_generation(root->fs_info->disk_super,
 335                                    cur_trans->transid);
 336         BUG_ON(ret);
 337         write_ctree_super(trans, root);
 338
 339         mutex_lock(&root->fs_info->fs_mutex);
 340         btrfs_finish_extent_commit(trans, root);
 341         mutex_lock(&root->fs_info->trans_mutex);
 342         cur_trans->commit_done = 1;
 343         wake_up(&cur_trans->commit_wait);
 344         put_transaction(cur_trans);
 345         put_transaction(cur_trans);
 346         mutex_unlock(&root->fs_info->trans_mutex);
 347         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 348
 349         drop_dirty_roots(root->fs_info->tree_root, &dirty_fs_roots);
 350         return ret;
 351 }
 352