[PATCH 1/3] Btrfs: pass lockdep rwsem metadata to async commit transaction
From: Sage Weil <hidden>
Date: 2012-08-30 22:26:22
Subsystem:
btrfs file system, filesystems (vfs and infrastructure), the rest · Maintainers:
Chris Mason, David Sterba, Alexander Viro, Christian Brauner, Linus Torvalds
The freeze rwsem is taken by sb_start_intwrite() and dropped during the commit_ or end_transaction(). In the async case, that happens in a worker thread. Tell lockdep the calling thread is releasing ownership of the rwsem and the async thread is picking it up. XFS plays the same trick in fs/xfs/xfs_aops.c. Signed-off-by: Sage Weil <redacted> --- fs/btrfs/transaction.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 17be3de..efc41a5 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c@@ -1228,6 +1228,14 @@ static void do_async_commit(struct work_struct *work) struct btrfs_async_commit *ac = container_of(work, struct btrfs_async_commit, work.work); + /* + * We've got freeze protection passed with the transaction. + * Tell lockdep about it. + */ + rwsem_acquire_read( + &ac->root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1], + 0, 1, _THIS_IP_); + btrfs_commit_transaction(ac->newtrans, ac->root); kfree(ac); }
@@ -1257,6 +1265,14 @@ int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans, atomic_inc(&cur_trans->use_count); btrfs_end_transaction(trans, root); + + /* + * Tell lockdep we've released the freeze rwsem, since the + * async commit thread will be the one to unlock it. + */ + rwsem_release(&root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1], + 1, _THIS_IP_); + schedule_delayed_work(&ac->work, 0); /* wait for transaction to start and unblock */
--
1.7.9.5