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, BTRFS_ROOT_TRANS_TAG);
  68                 root->commit_root = root->node;
  69                 get_bh(root->node);
  70         }
  71         root->last_trans = running_trans_id;
  72         h->transid = running_trans_id;
  73         h->transaction = root->fs_info->running_transaction;
  74         h->blocks_reserved = num_blocks;
  75         h->blocks_used = 0;
  76         root->fs_info->running_transaction->use_count++;
  77         mutex_unlock(&root->fs_info->trans_mutex);
  78         h->magic = h->magic2 = TRANS_MAGIC;
  79         return h;
  80 }
  81
  82 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
  83                           struct btrfs_root *root)
  84 {
  85         struct btrfs_transaction *cur_trans;
  86
  87         WARN_ON(trans->magic != TRANS_MAGIC);
  88         WARN_ON(trans->magic2 != TRANS_MAGIC);
  89         mutex_lock(&root->fs_info->trans_mutex);
  90         cur_trans = root->fs_info->running_transaction;
  91         WARN_ON(cur_trans->num_writers < 1);
  92         if (waitqueue_active(&cur_trans->writer_wait))
  93                 wake_up(&cur_trans->writer_wait);
  94         cur_trans->num_writers--;
  95         put_transaction(cur_trans);
  96         mutex_unlock(&root->fs_info->trans_mutex);
  97         memset(trans, 0, sizeof(*trans));
  98         kmem_cache_free(btrfs_trans_handle_cachep, trans);
  99         return 0;
 100 }
 101
 102
 103 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 104                                      struct btrfs_root *root)
 105 {
 106         filemap_write_and_wait(root->fs_info->btree_inode->i_mapping);
 107         return 0;
 108 }
 109
 110 int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
 111                             struct btrfs_root *root)
 112 {
 113         int ret;
 114         u64 old_extent_block;
 115         struct btrfs_fs_info *fs_info = root->fs_info;
 116         struct btrfs_root *tree_root = fs_info->tree_root;
 117         struct btrfs_root *extent_root = fs_info->extent_root;
 118         struct btrfs_root *inode_root = fs_info->inode_root;
 119
 120         btrfs_set_root_blocknr(&inode_root->root_item,
 121                                inode_root->node->b_blocknr);
 122         ret = btrfs_update_root(trans, tree_root,
 123                                 &inode_root->root_key,
 124                                 &inode_root->root_item);
 125         BUG_ON(ret);
 126         while(1) {
 127                 old_extent_block = btrfs_root_blocknr(&extent_root->root_item);
 128                 if (old_extent_block == extent_root->node->b_blocknr)
 129                         break;
 130                 btrfs_set_root_blocknr(&extent_root->root_item,
 131                                        extent_root->node->b_blocknr);
 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 printk("add dirty\n");
 174         while(1) {
 175                 ret = radix_tree_gang_lookup_tag(radix, (void **)gang, 0,
 176                                                  ARRAY_SIZE(gang),
 177                                                  BTRFS_ROOT_TRANS_TAG);
 178                 if (ret == 0)
 179                         break;
 180                 for (i = 0; i < ret; i++) {
 181                         root = gang[i];
 182                         radix_tree_tag_clear(radix, (unsigned long)root,
 183                                              BTRFS_ROOT_TRANS_TAG);
 184                         if (root->commit_root == root->node) {
 185                                 WARN_ON(root->node->b_blocknr !=
 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 printk("adding dirty root %Lu gen %Lu blocknr %Lu\n", root->root_key.objectid, root->root_key.offset, dirty->commit_root->b_blocknr);
 199                         root->root_key.offset = root->fs_info->generation;
 200                         btrfs_set_root_blocknr(&root->root_item,
 201                                                root->node->b_blocknr);
 202                         err = btrfs_insert_root(trans, root->fs_info->tree_root,
 203                                                 &root->root_key,
 204                                                 &root->root_item);
 205                         BUG_ON(err);
 206                         list_add(&dirty->list, list);
 207                 }
 208         }
 209 printk("add dirty done\n");
 210         return 0;
 211 }
 212
 213 int drop_dirty_roots(struct btrfs_root *tree_root, struct list_head *list)
 214 {
 215         struct dirty_root *dirty;
 216         struct btrfs_trans_handle *trans;
 217         int ret;
 218
 219         while(!list_empty(list)) {
 220                 dirty = list_entry(list->next, struct dirty_root, list);
 221                 list_del_init(&dirty->list);
 222                 trans = btrfs_start_transaction(tree_root, 1);
 223 printk("drop snapshot root %p, commit_root blocknr %Lu generation %Lu\n", dirty->root, dirty->commit_root->b_blocknr, dirty->snap_key.offset);
 224                 ret = btrfs_drop_snapshot(trans, dirty->root,
 225                                           dirty->commit_root);
 226                 BUG_ON(ret);
 227
 228 printk("del root objectid %Lu, offset %Lu\n", dirty->snap_key.objectid, dirty->snap_key.offset);
 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 list_head dirty_fs_roots;
 244         DEFINE_WAIT(wait);
 245
 246         INIT_LIST_HEAD(&dirty_fs_roots);
 247
 248         mutex_lock(&root->fs_info->trans_mutex);
 249         if (trans->transaction->in_commit) {
 250 printk("already in commit!, waiting\n");
 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         btrfs_set_super_generation(root->fs_info->disk_super,
 281                                    root->fs_info->generation + 1);
 282         mutex_unlock(&root->fs_info->trans_mutex);
 283         ret = btrfs_write_and_wait_transaction(trans, root);
 284         BUG_ON(ret);
 285
 286         write_ctree_super(trans, root);
 287         btrfs_finish_extent_commit(trans, root);
 288         mutex_lock(&root->fs_info->trans_mutex);
 289         cur_trans->commit_done = 1;
 290         wake_up(&cur_trans->commit_wait);
 291         put_transaction(cur_trans);
 292         put_transaction(cur_trans);
 293         mutex_unlock(&root->fs_info->trans_mutex);
 294         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 295
 296         drop_dirty_roots(root->fs_info->tree_root, &dirty_fs_roots);
 297         return ret;
 298 }
 299