From 9ffba8cda917c0158857426f0e74b64d0206aaa9 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Wed, 14 Aug 2013 11:33:56 -0400 Subject: [PATCH] Btrfs: fix heavy delalloc related deadlock 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) 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 Signed-off-by: Chris Mason --- 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 0632832..063e485 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -1413,6 +1413,13 @@ 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 572e21e..68391ec 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2277,6 +2277,7 @@ 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; } -- 2.7.4