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
 119         while(1) {
 120                 old_extent_block = btrfs_root_blocknr(&extent_root->root_item);
 121                 if (old_extent_block == extent_root->node->b_blocknr)
 122                         break;
 123                 btrfs_set_root_blocknr(&extent_root->root_item,
 124                                        extent_root->node->b_blocknr);
 125                 ret = btrfs_update_root(trans, tree_root,
 126                                         &extent_root->root_key,
 127                                         &extent_root->root_item);
 128                 BUG_ON(ret);
 129         }
 130         return 0;
 131 }
 132
 133 static int wait_for_commit(struct btrfs_root *root,
 134                            struct btrfs_transaction *commit)
 135 {
 136         DEFINE_WAIT(wait);
 137         while(!commit->commit_done) {
 138                 prepare_to_wait(&commit->commit_wait, &wait,
 139                                 TASK_UNINTERRUPTIBLE);
 140                 if (commit->commit_done)
 141                         break;
 142                 mutex_unlock(&root->fs_info->trans_mutex);
 143                 schedule();
 144                 mutex_lock(&root->fs_info->trans_mutex);
 145         }
 146         finish_wait(&commit->commit_wait, &wait);
 147         return 0;
 148 }
 149
 150 struct dirty_root {
 151         struct list_head list;
 152         struct btrfs_key snap_key;
 153         struct buffer_head *commit_root;
 154         struct btrfs_root *root;
 155 };
 156
 157 int add_dirty_roots(struct btrfs_trans_handle *trans,
 158                     struct radix_tree_root *radix, struct list_head *list)
 159 {
 160         struct dirty_root *dirty;
 161         struct btrfs_root *gang[8];
 162         struct btrfs_root *root;
 163         int i;
 164         int ret;
 165         int err;
 166         while(1) {
 167                 ret = radix_tree_gang_lookup_tag(radix, (void **)gang, 0,
 168                                                  ARRAY_SIZE(gang),
 169                                                  BTRFS_ROOT_TRANS_TAG);
 170                 if (ret == 0)
 171                         break;
 172                 for (i = 0; i < ret; i++) {
 173                         root = gang[i];
 174                         radix_tree_tag_clear(radix, (unsigned long)root,
 175                                              BTRFS_ROOT_TRANS_TAG);
 176                         if (root->commit_root == root->node) {
 177                                 WARN_ON(root->node->b_blocknr !=
 178                                         btrfs_root_blocknr(&root->root_item));
 179                                 brelse(root->commit_root);
 180                                 root->commit_root = NULL;
 181                                 continue;
 182                         }
 183                         dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
 184                         BUG_ON(!dirty);
 185                         memcpy(&dirty->snap_key, &root->root_key,
 186                                sizeof(root->root_key));
 187                         dirty->commit_root = root->commit_root;
 188                         root->commit_root = NULL;
 189                         dirty->root = root;
 190                         root->root_key.offset = root->fs_info->generation;
 191                         btrfs_set_root_blocknr(&root->root_item,
 192                                                root->node->b_blocknr);
 193                         err = btrfs_insert_root(trans, root->fs_info->tree_root,
 194                                                 &root->root_key,
 195                                                 &root->root_item);
 196                         BUG_ON(err);
 197                         list_add(&dirty->list, list);
 198                 }
 199         }
 200         return 0;
 201 }
 202
 203 int drop_dirty_roots(struct btrfs_root *tree_root, struct list_head *list)
 204 {
 205         struct dirty_root *dirty;
 206         struct btrfs_trans_handle *trans;
 207         int ret;
 208
 209         while(!list_empty(list)) {
 210                 dirty = list_entry(list->next, struct dirty_root, list);
 211                 list_del_init(&dirty->list);
 212                 trans = btrfs_start_transaction(tree_root, 1);
 213                 ret = btrfs_drop_snapshot(trans, dirty->root,
 214                                           dirty->commit_root);
 215                 BUG_ON(ret);
 216
 217                 ret = btrfs_del_root(trans, tree_root, &dirty->snap_key);
 218                 BUG_ON(ret);
 219                 ret = btrfs_end_transaction(trans, tree_root);
 220                 BUG_ON(ret);
 221                 kfree(dirty);
 222         }
 223         return 0;
 224 }
 225
 226 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 227                              struct btrfs_root *root)
 228 {
 229         int ret = 0;
 230         struct btrfs_transaction *cur_trans;
 231         struct list_head dirty_fs_roots;
 232         DEFINE_WAIT(wait);
 233
 234         INIT_LIST_HEAD(&dirty_fs_roots);
 235
 236         mutex_lock(&root->fs_info->trans_mutex);
 237         if (trans->transaction->in_commit) {
 238                 cur_trans = trans->transaction;
 239                 trans->transaction->use_count++;
 240                 btrfs_end_transaction(trans, root);
 241                 ret = wait_for_commit(root, cur_trans);
 242                 BUG_ON(ret);
 243                 put_transaction(cur_trans);
 244                 mutex_unlock(&root->fs_info->trans_mutex);
 245                 return 0;
 246         }
 247         cur_trans = trans->transaction;
 248         trans->transaction->in_commit = 1;
 249         while (trans->transaction->num_writers > 1) {
 250                 WARN_ON(cur_trans != trans->transaction);
 251                 prepare_to_wait(&trans->transaction->writer_wait, &wait,
 252                                 TASK_UNINTERRUPTIBLE);
 253                 if (trans->transaction->num_writers <= 1)
 254                         break;
 255                 mutex_unlock(&root->fs_info->trans_mutex);
 256                 schedule();
 257                 mutex_lock(&root->fs_info->trans_mutex);
 258                 finish_wait(&trans->transaction->writer_wait, &wait);
 259         }
 260         finish_wait(&trans->transaction->writer_wait, &wait);
 261         WARN_ON(cur_trans != trans->transaction);
 262         add_dirty_roots(trans, &root->fs_info->fs_roots_radix, &dirty_fs_roots);
 263         ret = btrfs_commit_tree_roots(trans, root);
 264         BUG_ON(ret);
 265         cur_trans = root->fs_info->running_transaction;
 266         root->fs_info->running_transaction = NULL;
 267         btrfs_set_super_generation(root->fs_info->disk_super,
 268                                    root->fs_info->generation + 1);
 269         mutex_unlock(&root->fs_info->trans_mutex);
 270         ret = btrfs_write_and_wait_transaction(trans, root);
 271         BUG_ON(ret);
 272
 273         write_ctree_super(trans, root);
 274         btrfs_finish_extent_commit(trans, root);
 275         mutex_lock(&root->fs_info->trans_mutex);
 276         cur_trans->commit_done = 1;
 277         wake_up(&cur_trans->commit_wait);
 278         put_transaction(cur_trans);
 279         put_transaction(cur_trans);
 280         mutex_unlock(&root->fs_info->trans_mutex);
 281         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 282
 283         drop_dirty_roots(root->fs_info->tree_root, &dirty_fs_roots);
 284         return ret;
 285 }
 286