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Btrfs: fix NULL pointer after aborting a transaction 

While doing cleanup work on an aborted transaction, we've set
the global running transaction pointer to NULL _before_ waiting all
other transaction handles to finish, so others'd hit NULL pointer
crash when referencing the global running transaction pointer.

This first sets a hint to avoid new transaction handle joining, then
waits other existing handles to abort or finish so that we can safely
set the above global pointer to NULL.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
This commit is contained in:
Liu Bo 2013-02-27 13:28:25 +00:00 committed by Josef Bacik
parent 3321719ed6
commit f094ac32ab
1 changed files with 7 additions and 1 deletions
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8
fs/btrfs/transaction.c
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@ -1447,6 +1447,7 @@ static void cleanup_transaction(struct btrfs_trans_handle *trans,
struct btrfs_root *root, int err)
{
struct btrfs_transaction *cur_trans = trans->transaction;
DEFINE_WAIT(wait);
WARN_ON(trans->use_count > 1);
@ -1455,8 +1456,13 @@ static void cleanup_transaction(struct btrfs_trans_handle *trans,
spin_lock(&root->fs_info->trans_lock);
list_del_init(&cur_trans->list);
if (cur_trans == root->fs_info->running_transaction) {
root->fs_info->trans_no_join = 1;
spin_unlock(&root->fs_info->trans_lock);
wait_event(cur_trans->writer_wait,
atomic_read(&cur_trans->num_writers) == 1);
spin_lock(&root->fs_info->trans_lock);
root->fs_info->running_transaction = NULL;
root->fs_info->trans_no_join = 0;
}
spin_unlock(&root->fs_info->trans_lock);