Btrfs: transaction rework
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
new file mode 100644
index 0000000..8dc1c17
--- /dev/null
+++ b/fs/btrfs/transaction.c
@@ -0,0 +1,199 @@
+#include <linux/module.h>
+#include <linux/fs.h>
+#include "ctree.h"
+#include "disk-io.h"
+#include "transaction.h"
+
+
+static void put_transaction(struct btrfs_transaction *transaction)
+{
+ transaction->use_count--;
+ if (transaction->use_count == 0)
+ kfree(transaction);
+}
+
+static int join_transaction(struct btrfs_root *root)
+{
+ struct btrfs_transaction *cur_trans;
+ cur_trans = root->fs_info->running_transaction;
+ if (!cur_trans) {
+ cur_trans = kmalloc(sizeof(*cur_trans), GFP_NOFS);
+ BUG_ON(!cur_trans);
+ root->fs_info->running_transaction = cur_trans;
+ cur_trans->num_writers = 0;
+ cur_trans->transid = root->root_key.offset + 1;
+ init_waitqueue_head(&cur_trans->writer_wait);
+ init_waitqueue_head(&cur_trans->commit_wait);
+ cur_trans->in_commit = 0;
+ cur_trans->use_count = 0;
+ cur_trans->commit_done = 0;
+ }
+ cur_trans->num_writers++;
+ return 0;
+}
+
+struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
+ int num_blocks)
+{
+ struct btrfs_trans_handle *h = kmalloc(sizeof(*h), GFP_NOFS);
+ int ret;
+
+ mutex_lock(&root->fs_info->trans_mutex);
+ ret = join_transaction(root);
+ BUG_ON(ret);
+ h->transid = root->fs_info->running_transaction->transid;
+ h->transaction = root->fs_info->running_transaction;
+ h->blocks_reserved = num_blocks;
+ h->blocks_used = 0;
+ root->fs_info->running_transaction->use_count++;
+ mutex_unlock(&root->fs_info->trans_mutex);
+ return h;
+}
+
+int btrfs_end_transaction(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root)
+{
+ struct btrfs_transaction *cur_trans;
+ mutex_lock(&root->fs_info->trans_mutex);
+ cur_trans = root->fs_info->running_transaction;
+ WARN_ON(cur_trans->num_writers <= 1);
+ if (waitqueue_active(&cur_trans->writer_wait))
+ wake_up(&cur_trans->writer_wait);
+ cur_trans->num_writers--;
+ put_transaction(cur_trans);
+ mutex_unlock(&root->fs_info->trans_mutex);
+ kfree(trans);
+ return 0;
+}
+
+
+int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root)
+{
+ filemap_write_and_wait(root->fs_info->sb->s_bdev->bd_inode->i_mapping);
+ return 0;
+}
+
+int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root)
+{
+ int ret;
+ u64 old_extent_block;
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ struct btrfs_root *tree_root = fs_info->tree_root;
+ struct btrfs_root *extent_root = fs_info->extent_root;
+ struct btrfs_root *inode_root = fs_info->inode_root;
+
+ btrfs_set_root_blocknr(&inode_root->root_item,
+ inode_root->node->b_blocknr);
+ ret = btrfs_update_root(trans, tree_root,
+ &inode_root->root_key,
+ &inode_root->root_item);
+ BUG_ON(ret);
+ while(1) {
+ old_extent_block = btrfs_root_blocknr(&extent_root->root_item);
+ if (old_extent_block == extent_root->node->b_blocknr)
+ break;
+ btrfs_set_root_blocknr(&extent_root->root_item,
+ extent_root->node->b_blocknr);
+ ret = btrfs_update_root(trans, tree_root,
+ &extent_root->root_key,
+ &extent_root->root_item);
+ BUG_ON(ret);
+ }
+ return 0;
+}
+
+static int wait_for_commit(struct btrfs_root *root,
+ struct btrfs_transaction *commit)
+{
+ DEFINE_WAIT(wait);
+ commit->use_count++;
+ while(!commit->commit_done) {
+ prepare_to_wait(&commit->commit_wait, &wait,
+ TASK_UNINTERRUPTIBLE);
+ if (commit->commit_done)
+ break;
+ mutex_unlock(&root->fs_info->trans_mutex);
+ schedule();
+ mutex_lock(&root->fs_info->trans_mutex);
+ }
+ finish_wait(&commit->commit_wait, &wait);
+ return 0;
+}
+
+int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root)
+{
+ int ret = 0;
+ struct buffer_head *snap = root->commit_root;
+ struct btrfs_key snap_key;
+ struct btrfs_transaction *cur_trans;
+ DEFINE_WAIT(wait);
+
+ mutex_lock(&root->fs_info->trans_mutex);
+ if (trans->transaction->in_commit) {
+ cur_trans = trans->transaction;
+ trans->transaction->use_count++;
+ btrfs_end_transaction(trans, root);
+ ret = wait_for_commit(root, cur_trans);
+ BUG_ON(ret);
+ put_transaction(cur_trans);
+ mutex_unlock(&root->fs_info->trans_mutex);
+ return 0;
+ }
+ while (trans->transaction->num_writers > 1) {
+ prepare_to_wait(&trans->transaction->writer_wait, &wait,
+ TASK_UNINTERRUPTIBLE);
+ if (trans->transaction->num_writers <= 1)
+ break;
+ mutex_unlock(&root->fs_info->trans_mutex);
+ schedule();
+ mutex_lock(&root->fs_info->trans_mutex);
+ }
+ finish_wait(&trans->transaction->writer_wait, &wait);
+
+ cur_trans = root->fs_info->running_transaction;
+ root->fs_info->running_transaction = NULL;
+ mutex_unlock(&root->fs_info->trans_mutex);
+
+ memcpy(&snap_key, &root->root_key, sizeof(snap_key));
+ root->root_key.offset++;
+
+ if (btrfs_root_blocknr(&root->root_item) != root->node->b_blocknr) {
+ btrfs_set_root_blocknr(&root->root_item, root->node->b_blocknr);
+ ret = btrfs_insert_root(trans, root->fs_info->tree_root,
+ &root->root_key, &root->root_item);
+ BUG_ON(ret);
+ }
+
+ ret = btrfs_commit_tree_roots(trans, root);
+ BUG_ON(ret);
+
+ ret = btrfs_write_and_wait_transaction(trans, root);
+ BUG_ON(ret);
+
+ write_ctree_super(trans, root);
+ btrfs_finish_extent_commit(trans, root->fs_info->extent_root);
+ btrfs_finish_extent_commit(trans, root->fs_info->tree_root);
+ put_transaction(cur_trans);
+ kfree(trans);
+
+ if (root->node != root->commit_root) {
+ trans = btrfs_start_transaction(root, 1);
+ root->commit_root = root->node;
+ get_bh(root->node);
+ ret = btrfs_drop_snapshot(trans, root, snap);
+ BUG_ON(ret);
+
+ ret = btrfs_del_root(trans, root->fs_info->tree_root,
+ &snap_key);
+ BUG_ON(ret);
+ root->fs_info->generation = root->root_key.offset + 1;
+ ret = btrfs_end_transaction(trans, root);
+ BUG_ON(ret);
+ }
+
+ return ret;
+}
+