From patchwork Tue Jul 19 04:09:52 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ioannis Angelakopoulos X-Patchwork-Id: 12922093 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 084CEC433EF for ; Tue, 19 Jul 2022 04:12:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235793AbiGSEMs (ORCPT ); Tue, 19 Jul 2022 00:12:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59630 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234366AbiGSEMr (ORCPT ); Tue, 19 Jul 2022 00:12:47 -0400 Received: from mx0b-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3A6BC3AB08 for ; Mon, 18 Jul 2022 21:12:46 -0700 (PDT) Received: from pps.filterd (m0109332.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 26IGhxwR030353 for ; Mon, 18 Jul 2022 21:12:45 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : content-type; s=facebook; bh=9j9IEWtrl4Tf9dtlhASpJUIKoFMWGsQiJBCZHLWxbMQ=; b=CxmOdBPhYbXrhgzRPmBTzP+OS1nFdIaWrEduAY1Hdx6PJlaO9Q8THDVX/RKZWZD2SyQ1 v74OJ+qiCeRxHGn4m4NJdrLN3SJ05tB079MsBimmRwHxc5JHJXlJWOinDkg/h/mbO3wH qFxtJUwJ1R5wojhuvPXOr9/1FuIixcaK+zs= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3hcs5krq9d-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Mon, 18 Jul 2022 21:12:45 -0700 Received: from twshared25478.08.ash9.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::4) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.28; Mon, 18 Jul 2022 21:12:44 -0700 Received: by devvm7778.ftw0.facebook.com (Postfix, from userid 558217) id D13AE24A8AD4; Mon, 18 Jul 2022 21:12:33 -0700 (PDT) From: Ioannis Angelakopoulos To: , Subject: [PATCH v2 1/5] btrfs: Add a lockdep model for the num_writers wait event Date: Mon, 18 Jul 2022 21:09:52 -0700 Message-ID: <20220719040954.3964407-2-iangelak@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220719040954.3964407-1-iangelak@fb.com> References: <20220719040954.3964407-1-iangelak@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-GUID: mVeYtLF_iOggdt_WduQnnHyIdOY319-8 X-Proofpoint-ORIG-GUID: mVeYtLF_iOggdt_WduQnnHyIdOY319-8 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.883,Hydra:6.0.517,FMLib:17.11.122.1 definitions=2022-07-18_22,2022-07-18_01,2022-06-22_01 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org Annotate the num_writers wait event in fs/btrfs/transaction.c with lockdep in order to catch deadlocks involving this wait event. Use a read/write lockdep map for the annotation. A thread starting/joining the transaction acquires the map as a reader when it increments cur_trans->num_writers and it acquires the map as a writer before it blocks on the wait event. Signed-off-by: Ioannis Angelakopoulos Reviewed-by: Josef Bacik --- fs/btrfs/ctree.h | 14 ++++++++++++++ fs/btrfs/disk-io.c | 6 ++++++ fs/btrfs/transaction.c | 37 ++++++++++++++++++++++++++++++++----- 3 files changed, 52 insertions(+), 5 deletions(-) diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 202496172059..999868734be7 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -1095,6 +1095,8 @@ struct btrfs_fs_info { /* Updates are not protected by any lock */ struct btrfs_commit_stats commit_stats; + struct lockdep_map btrfs_trans_num_writers_map; + #ifdef CONFIG_BTRFS_FS_REF_VERIFY spinlock_t ref_verify_lock; struct rb_root block_tree; @@ -1175,6 +1177,18 @@ enum { BTRFS_ROOT_UNFINISHED_DROP, }; +#define btrfs_might_wait_for_event(b, lock) \ + do { \ + rwsem_acquire(&b->lock##_map, 0, 0, _THIS_IP_); \ + rwsem_release(&b->lock##_map, _THIS_IP_); \ + } while (0) + +#define btrfs_lockdep_acquire(b, lock) \ + rwsem_acquire_read(&b->lock##_map, 0, 0, _THIS_IP_) + +#define btrfs_lockdep_release(b, lock) \ + rwsem_release(&b->lock##_map, _THIS_IP_) + static inline void btrfs_wake_unfinished_drop(struct btrfs_fs_info *fs_info) { clear_and_wake_up_bit(BTRFS_FS_UNFINISHED_DROPS, &fs_info->flags); diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 3fac429cf8a4..01a5a49a3a11 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -3046,6 +3046,8 @@ static int __cold init_tree_roots(struct btrfs_fs_info *fs_info) void btrfs_init_fs_info(struct btrfs_fs_info *fs_info) { + static struct lock_class_key btrfs_trans_num_writers_key; + INIT_RADIX_TREE(&fs_info->fs_roots_radix, GFP_ATOMIC); INIT_RADIX_TREE(&fs_info->buffer_radix, GFP_ATOMIC); INIT_LIST_HEAD(&fs_info->trans_list); @@ -3074,6 +3076,10 @@ 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); + lockdep_init_map(&fs_info->btrfs_trans_num_writers_map, + "btrfs_trans_num_writers", + &btrfs_trans_num_writers_key, 0); + 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..d8287ec890bc 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 +2539,9 @@ 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; } /*