From: Ioannis Angelakopoulos iangelak@fb.com
[ Upstream commit e1489b4fe6045a79a5e9c658eed65311977e230a ]
Annotate the num_writers wait event in fs/btrfs/transaction.c with lockdep in order to catch deadlocks involving this wait event.
Reviewed-by: Josef Bacik josef@toxicpanda.com Signed-off-by: Ioannis Angelakopoulos iangelak@fb.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/btrfs/ctree.h | 6 ++++++ fs/btrfs/disk-io.c | 2 ++ fs/btrfs/transaction.c | 38 +++++++++++++++++++++++++++++++++----- 3 files changed, 41 insertions(+), 5 deletions(-)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index dfeb7174219e..707e644bab92 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -1092,6 +1092,12 @@ struct btrfs_fs_info { /* Updates are not protected by any lock */ struct btrfs_commit_stats commit_stats;
+ /* + * Annotations for transaction events (structures are empty when + * compiled without lockdep). + */ + struct lockdep_map btrfs_trans_num_writers_map; + #ifdef CONFIG_BTRFS_FS_REF_VERIFY spinlock_t ref_verify_lock; struct rb_root block_tree; diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 2633137c3e9f..a04b32f7df9d 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2990,6 +2990,8 @@ void btrfs_init_fs_info(struct btrfs_fs_info *fs_info) mutex_init(&fs_info->zoned_data_reloc_io_lock); seqlock_init(&fs_info->profiles_lock);
+ btrfs_lockdep_init_map(fs_info, btrfs_trans_num_writers); + INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots); INIT_LIST_HEAD(&fs_info->space_info); INIT_LIST_HEAD(&fs_info->tree_mod_seq_list); diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 0bec10740ad3..b3cb54d852f8 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -313,6 +313,7 @@ static noinline int join_transaction(struct btrfs_fs_info *fs_info, atomic_inc(&cur_trans->num_writers); extwriter_counter_inc(cur_trans, type); spin_unlock(&fs_info->trans_lock); + btrfs_lockdep_acquire(fs_info, btrfs_trans_num_writers); return 0; } spin_unlock(&fs_info->trans_lock); @@ -334,16 +335,20 @@ static noinline int join_transaction(struct btrfs_fs_info *fs_info, if (!cur_trans) return -ENOMEM;
+ btrfs_lockdep_acquire(fs_info, btrfs_trans_num_writers); + spin_lock(&fs_info->trans_lock); if (fs_info->running_transaction) { /* * someone started a transaction after we unlocked. Make sure * to redo the checks above */ + btrfs_lockdep_release(fs_info, btrfs_trans_num_writers); kfree(cur_trans); goto loop; } else if (BTRFS_FS_ERROR(fs_info)) { spin_unlock(&fs_info->trans_lock); + btrfs_lockdep_release(fs_info, btrfs_trans_num_writers); kfree(cur_trans); return -EROFS; } @@ -1022,6 +1027,9 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans, extwriter_counter_dec(cur_trans, trans->type);
cond_wake_up(&cur_trans->writer_wait); + + btrfs_lockdep_release(info, btrfs_trans_num_writers); + btrfs_put_transaction(cur_trans);
if (current->journal_info == trans) @@ -1994,6 +2002,12 @@ static void cleanup_transaction(struct btrfs_trans_handle *trans, int err) if (cur_trans == fs_info->running_transaction) { cur_trans->state = TRANS_STATE_COMMIT_DOING; spin_unlock(&fs_info->trans_lock); + + /* + * The thread has already released the lockdep map as reader + * already in btrfs_commit_transaction(). + */ + btrfs_might_wait_for_event(fs_info, btrfs_trans_num_writers); wait_event(cur_trans->writer_wait, atomic_read(&cur_trans->num_writers) == 1);
@@ -2222,7 +2236,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
btrfs_put_transaction(prev_trans); if (ret) - goto cleanup_transaction; + goto lockdep_release; } else { spin_unlock(&fs_info->trans_lock); } @@ -2236,7 +2250,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans) */ if (BTRFS_FS_ERROR(fs_info)) { ret = -EROFS; - goto cleanup_transaction; + goto lockdep_release; } }
@@ -2250,19 +2264,21 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
ret = btrfs_start_delalloc_flush(fs_info); if (ret) - goto cleanup_transaction; + goto lockdep_release;
ret = btrfs_run_delayed_items(trans); if (ret) - goto cleanup_transaction; + goto lockdep_release;
wait_event(cur_trans->writer_wait, extwriter_counter_read(cur_trans) == 0);
/* some pending stuffs might be added after the previous flush. */ ret = btrfs_run_delayed_items(trans); - if (ret) + if (ret) { + btrfs_lockdep_release(fs_info, btrfs_trans_num_writers); goto cleanup_transaction; + }
btrfs_wait_delalloc_flush(fs_info);
@@ -2284,6 +2300,14 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans) add_pending_snapshot(trans); cur_trans->state = TRANS_STATE_COMMIT_DOING; spin_unlock(&fs_info->trans_lock); + + /* + * The thread has started/joined the transaction thus it holds the + * lockdep map as a reader. It has to release it before acquiring the + * lockdep map as a writer. + */ + btrfs_lockdep_release(fs_info, btrfs_trans_num_writers); + btrfs_might_wait_for_event(fs_info, btrfs_trans_num_writers); wait_event(cur_trans->writer_wait, atomic_read(&cur_trans->num_writers) == 1);
@@ -2515,6 +2539,10 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans) cleanup_transaction(trans, ret);
return ret; + +lockdep_release: + btrfs_lockdep_release(fs_info, btrfs_trans_num_writers); + goto cleanup_transaction; }
/*