On wed, 14 Aug 2013 11:41:00 -0400, Josef Bacik wrote: > I added a patch where we started taking the ordered operations mutex when we > waited on ordered extents. We need this because we splice the list and > process > it, so if a flusher came in during this scenario it would think the list was > empty and we'd usually get an early ENOSPC. The problem with this is that > this > lock is used in transaction committing. So we end up with something like this > > Transaction commit > -> wait on writers > > Delalloc flusher > -> run_ordered_operations (holds mutex) > ->wait for filemap-flush to do its thing > > flush task > -> cow_file_range > ->wait on btrfs_join_transaction because we're commiting > > some other task > -> commit_transaction because we notice trans->transaction->flush is set > -> run_ordered_operations (hang on mutex)
Sorry, I can not understand this explanation. As far as I know, if the flush task waits on btrfs_join_transaction(), it means the transaction is under commit (state = TRANS_STATE_COMMIT_DOING), and all the external writers(TRANS_START/TRANS_ATTACH/ TRANS_USERSPACE) have quitted the current transaction, so no one would try to call run_ordered_operations(). Could you show us the reproduce steps? Thanks Miao > > We need to disentangle the ordered operations flushing from the delalloc > flushing, since they are separate things. This solves the deadlock issue I > was > seeing. Thanks, > > Signed-off-by: Josef Bacik <jba...@fusionio.com> > --- > fs/btrfs/ctree.h | 7 +++++++ > fs/btrfs/disk-io.c | 1 + > fs/btrfs/ordered-data.c | 4 ++-- > 3 files changed, 10 insertions(+), 2 deletions(-) > > diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h > index ea4cc16..d79e32c 100644 > --- a/fs/btrfs/ctree.h > +++ b/fs/btrfs/ctree.h > @@ -1418,6 +1418,13 @@ struct btrfs_fs_info { > * before jumping into the main commit. > */ > struct mutex ordered_operations_mutex; > + > + /* > + * Same as ordered_operations_mutex except this is for ordered extents > + * and not the operations. > + */ > + struct mutex ordered_extent_flush_mutex; > + > struct rw_semaphore extent_commit_sem; > > struct rw_semaphore cleanup_work_sem; > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c > index c82025d..880dcde 100644 > --- a/fs/btrfs/disk-io.c > +++ b/fs/btrfs/disk-io.c > @@ -2288,6 +2288,7 @@ int open_ctree(struct super_block *sb, > > > mutex_init(&fs_info->ordered_operations_mutex); > + mutex_init(&fs_info->ordered_extent_flush_mutex); > mutex_init(&fs_info->tree_log_mutex); > mutex_init(&fs_info->chunk_mutex); > mutex_init(&fs_info->transaction_kthread_mutex); > diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c > index 8136982..b52b2c4 100644 > --- a/fs/btrfs/ordered-data.c > +++ b/fs/btrfs/ordered-data.c > @@ -671,7 +671,7 @@ int btrfs_run_ordered_operations(struct > btrfs_trans_handle *trans, > INIT_LIST_HEAD(&splice); > INIT_LIST_HEAD(&works); > > - mutex_lock(&root->fs_info->ordered_operations_mutex); > + mutex_lock(&root->fs_info->ordered_extent_flush_mutex); > spin_lock(&root->fs_info->ordered_root_lock); > list_splice_init(&cur_trans->ordered_operations, &splice); > while (!list_empty(&splice)) { > @@ -718,7 +718,7 @@ out: > list_del_init(&work->list); > btrfs_wait_and_free_delalloc_work(work); > } > - mutex_unlock(&root->fs_info->ordered_operations_mutex); > + mutex_unlock(&root->fs_info->ordered_extent_flush_mutex); > return ret; > } > > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html