diff options
| author | Miao Xie <miaox@cn.fujitsu.com> | 2013-02-20 09:16:24 +0000 |
|---|---|---|
| committer | Josef Bacik <jbacik@fusionio.com> | 2013-02-20 13:00:03 -0500 |
| commit | 178260b2c14969f29ba39a78df74ed485abc6203 (patch) | |
| tree | 56bf3f573112f898f3439d6e0a11d76fbb925bb0 /fs | |
| parent | 4b82490649f5c8ecbf888752c325ea68831c497e (diff) | |
Btrfs: fix the deadlock between the transaction start/attach and commit
Now btrfs_commit_transaction() does this
ret = btrfs_run_ordered_operations(root, 0)
which async flushes all inodes on the ordered operations list, it introduced
a deadlock that transaction-start task, transaction-commit task and the flush
workers waited for each other.
(See the following URL to get the detail
http://marc.info/?l=linux-btrfs&m=136070705732646&w=2)
As we know, if ->in_commit is set, it means someone is committing the
current transaction, we should not try to join it if we are not JOIN
or JOIN_NOLOCK, wait is the best choice for it. In this way, we can avoid
the above problem. In this way, there is another benefit: there is no new
transaction handle to block the transaction which is on the way of commit,
once we set ->in_commit.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/btrfs/transaction.c | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 425d5b57d37..5767ea1c015 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -50,6 +50,14 @@ static noinline void switch_commit_root(struct btrfs_root *root) root->commit_root = btrfs_root_node(root); } +static inline int can_join_transaction(struct btrfs_transaction *trans, + int type) +{ + return !(trans->in_commit && + type != TRANS_JOIN && + type != TRANS_JOIN_NOLOCK); +} + /* * either allocate a new transaction or hop into the existing one */ @@ -85,6 +93,10 @@ loop: spin_unlock(&fs_info->trans_lock); return cur_trans->aborted; } + if (!can_join_transaction(cur_trans, type)) { + spin_unlock(&fs_info->trans_lock); + return -EBUSY; + } atomic_inc(&cur_trans->use_count); atomic_inc(&cur_trans->num_writers); cur_trans->num_joined++; @@ -360,8 +372,11 @@ again: do { ret = join_transaction(root, type); - if (ret == -EBUSY) + if (ret == -EBUSY) { wait_current_trans(root); + if (unlikely(type == TRANS_ATTACH)) + ret = -ENOENT; + } } while (ret == -EBUSY); if (ret < 0) { |