From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f195.google.com ([209.85.223.195]:35467 "EHLO mail-io0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932236AbcJLJQ3 (ORCPT ); Wed, 12 Oct 2016 05:16:29 -0400 Received: by mail-io0-f195.google.com with SMTP id p26so2689253ioo.2 for ; Wed, 12 Oct 2016 02:16:23 -0700 (PDT) MIME-Version: 1.0 Reply-To: fdmanana@gmail.com In-Reply-To: <8444eb13f2a41d2a72ed0e7bd7cfc1f3@synology.com> References: <1475834728-16198-1-git-send-email-robbieko@synology.com> <8444eb13f2a41d2a72ed0e7bd7cfc1f3@synology.com> From: Filipe Manana Date: Wed, 12 Oct 2016 10:04:14 +0100 Message-ID: Subject: Re: [PATCH] Btrfs: fix fsync deadlock in log_new_dir_dentries To: robbieko Cc: "linux-btrfs@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Tue, Oct 11, 2016 at 8:47 AM, robbieko wrote: > Hi Filipe: > > why did you replace the continue statement with a break statement: > because we released ahead of the path, it can not continue to use, > need to jump out, and then go to again. Seeing the code and not only the patch's diff, I can see it now, thanks. Btw, please avoid top posting, it's not how you should reply to a thread, see [1]. [1] http://linux.sgms-centre.com/misc/netiquette.php > > supplement: > We found a fsync deadlock ie. 32021->32020->32028->14431->14436->32021, the > number id pid. > extent_buffer: start:207060992, len:16384 > locker pid: 32020 read lock > wait pid: 32021 write lock > extent_buffer: start:14730821632, len:16384 > locker pid: 32028 read lock > wait pid: 32020 write lock > extent_buffer: start:446503813120, len:16384 > locker pid: 14431 write lock > wait pid: 32028 read lock > extent_buffer: start:446503845888, len: 16384 > locker pid: 14436 write lock > wait pid: 14431 write lock > extent_buffer: start: 446504386560, len: 16384 > locker pid: 32021 write lock > wait pid: 14436 write lock > > Thanks. > Robbie Ko > > Filipe Manana 於 2016-10-07 18:46 寫到: > >> On Fri, Oct 7, 2016 at 11:43 AM, robbieko wrote: >>> >>> Hi Filipe, >>> >>> I am sorry, I express not clear enough. >>> This number is pid, and the above are their call trace respectively. >> >> >> And why did you replace the continue statement with a break statement? >> >> Also please avoid mixing inline replies with top posting, it just >> breaks the thread. >> >> thanks >> >>> >>> Thanks. >>> robbieko >>> >>> Filipe Manana 於 2016-10-07 18:23 寫道： >>> >>> On Fri, Oct 7, 2016 at 11:05 AM, robbieko wrote: >>>> >>>> From: Robbie Ko >>>> >>>> We found a fsync deadlock ie. 32021->32020->32028->14431->14436->32021, >>>> in log_new_dir_dentries, because btrfs_search_forward get path lock, >>>> then >>>> call btrfs_iget will get another extent_buffer lock, maybe occur >>>> deadlock. >>> >>> >>> What are those numbers? Are they inode numbers? >>> If so you're suggesting a deadlock due to recursive logging of the same >>> inode. >>> However the trace below, and the code change, has nothing to do with >>> that. >>> It's just about btrfs_iget trying to do a search on a btree and >>> attempting to read lock some node/leaf that already has a write lock >>> acquired previously by the same task. >>> >>> Please be more clear on your change logs. >>> >>> >>>> >>>> we can release path before call btrfs_iget, avoid deadlock occur. >>>> >>>> some process call trace like below: >>>> [ 4077.478852] kworker/u24:10 D ffff88107fc90640 0 14431 2 >>>> 0x00000000 >>>> [ 4077.486752] Workqueue: btrfs-endio-write btrfs_endio_write_helper >>>> [btrfs] >>>> [ 4077.494346] ffff880ffa56bad0 0000000000000046 0000000000009000 >>>> ffff880ffa56bfd8 >>>> [ 4077.502629] ffff880ffa56bfd8 ffff881016ce21c0 ffffffffa06ecb26 >>>> ffff88101a5d6138 >>>> [ 4077.510915] ffff880ebb5173b0 ffff880ffa56baf8 ffff880ebb517410 >>>> ffff881016ce21c0 >>>> [ 4077.519202] Call Trace: >>>> [ 4077.528752] [] ? btrfs_tree_lock+0xdd/0x2f0 >>>> [btrfs] >>>> [ 4077.536049] [] ? wake_up_atomic_t+0x30/0x30 >>>> [ 4077.542574] [] ? btrfs_search_slot+0x79f/0xb10 >>>> [btrfs] >>>> [ 4077.550171] [] ? >>>> btrfs_lookup_file_extent+0x33/0x40 >>>> [btrfs] >>>> [ 4077.558252] [] ? __btrfs_drop_extents+0x13b/0xdf0 >>>> [btrfs] >>>> [ 4077.566140] [] ? add_delayed_data_ref+0xe2/0x150 >>>> [btrfs] >>>> [ 4077.573928] [] ? >>>> btrfs_add_delayed_data_ref+0x149/0x1d0 [btrfs] >>>> [ 4077.582399] [] ? __set_extent_bit+0x4c0/0x5c0 >>>> [btrfs] >>>> [ 4077.589896] [] ? >>>> insert_reserved_file_extent.constprop.75+0xa4/0x320 [btrfs] >>>> [ 4077.599632] [] ? start_transaction+0x8d/0x470 >>>> [btrfs] >>>> [ 4077.607134] [] ? >>>> btrfs_finish_ordered_io+0x2e7/0x600 >>>> [btrfs] >>>> [ 4077.615329] [] ? process_one_work+0x142/0x3d0 >>>> [ 4077.622043] [] ? worker_thread+0x109/0x3b0 >>>> [ 4077.628459] [] ? >>>> manage_workers.isra.26+0x270/0x270 >>>> [ 4077.635759] [] ? kthread+0xaf/0xc0 >>>> [ 4077.641404] [] ? >>>> kthread_create_on_node+0x110/0x110 >>>> [ 4077.648696] [] ? ret_from_fork+0x58/0x90 >>>> [ 4077.654926] [] ? >>>> kthread_create_on_node+0x110/0x110 >>>> >>>> [ 4078.358087] kworker/u24:15 D ffff88107fcd0640 0 14436 2 >>>> 0x00000000 >>>> [ 4078.365981] Workqueue: btrfs-endio-write btrfs_endio_write_helper >>>> [btrfs] >>>> [ 4078.373574] ffff880ffa57fad0 0000000000000046 0000000000009000 >>>> ffff880ffa57ffd8 >>>> [ 4078.381864] ffff880ffa57ffd8 ffff88103004d0a0 ffffffffa06ecb26 >>>> ffff88101a5d6138 >>>> [ 4078.390163] ffff880fbeffc298 ffff880ffa57faf8 ffff880fbeffc2f8 >>>> ffff88103004d0a0 >>>> [ 4078.398466] Call Trace: >>>> [ 4078.408019] [] ? btrfs_tree_lock+0xdd/0x2f0 >>>> [btrfs] >>>> [ 4078.415322] [] ? wake_up_atomic_t+0x30/0x30 >>>> [ 4078.421844] [] ? btrfs_search_slot+0x79f/0xb10 >>>> [btrfs] >>>> [ 4078.429438] [] ? >>>> btrfs_lookup_file_extent+0x33/0x40 >>>> [btrfs] >>>> [ 4078.437518] [] ? __btrfs_drop_extents+0x13b/0xdf0 >>>> [btrfs] >>>> [ 4078.445404] [] ? add_delayed_data_ref+0xe2/0x150 >>>> [btrfs] >>>> [ 4078.453194] [] ? >>>> btrfs_add_delayed_data_ref+0x149/0x1d0 [btrfs] >>>> [ 4078.461663] [] ? __set_extent_bit+0x4c0/0x5c0 >>>> [btrfs] >>>> [ 4078.469161] [] ? >>>> insert_reserved_file_extent.constprop.75+0xa4/0x320 [btrfs] >>>> [ 4078.478893] [] ? start_transaction+0x8d/0x470 >>>> [btrfs] >>>> [ 4078.486388] [] ? >>>> btrfs_finish_ordered_io+0x2e7/0x600 >>>> [btrfs] >>>> [ 4078.494561] [] ? process_one_work+0x142/0x3d0 >>>> [ 4078.501278] [] ? >>>> pwq_activate_delayed_work+0x27/0x40 >>>> [ 4078.508673] [] ? worker_thread+0x109/0x3b0 >>>> [ 4078.515098] [] ? >>>> manage_workers.isra.26+0x270/0x270 >>>> [ 4078.522396] [] ? kthread+0xaf/0xc0 >>>> [ 4078.528032] [] ? >>>> kthread_create_on_node+0x110/0x110 >>>> [ 4078.535325] [] ? ret_from_fork+0x58/0x90 >>>> [ 4078.541552] [] ? >>>> kthread_create_on_node+0x110/0x110 >>>> >>>> [ 4079.355824] user-space-program D ffff88107fd30640 0 32020 1 >>>> 0x00000000 >>>> [ 4079.363716] ffff880eae8eba10 0000000000000086 0000000000009000 >>>> ffff880eae8ebfd8 >>>> [ 4079.372003] ffff880eae8ebfd8 ffff881016c162c0 ffffffffa06ecb26 >>>> ffff88101a5d6138 >>>> [ 4079.380294] ffff880fbed4b4c8 ffff880eae8eba38 ffff880fbed4b528 >>>> ffff881016c162c0 >>>> [ 4079.388586] Call Trace: >>>> [ 4079.398134] [] ? btrfs_tree_lock+0x85/0x2f0 >>>> [btrfs] >>>> [ 4079.405431] [] ? wake_up_atomic_t+0x30/0x30 >>>> [ 4079.411955] [] ? btrfs_lock_root_node+0x2b/0x40 >>>> [btrfs] >>>> [ 4079.419644] [] ? btrfs_search_slot+0xa03/0xb10 >>>> [btrfs] >>>> [ 4079.427237] [] ? btrfs_buffer_uptodate+0x52/0x70 >>>> [btrfs] >>>> [ 4079.435041] [] ? >>>> generic_bin_search.constprop.38+0x80/0x190 [btrfs] >>>> [ 4079.443897] [] ? >>>> btrfs_insert_empty_items+0x74/0xd0 >>>> [btrfs] >>>> [ 4079.451975] [] ? copy_items+0x128/0x850 [btrfs] >>>> [ 4079.458890] [] ? btrfs_log_inode+0x629/0xbf3 >>>> [btrfs] >>>> [ 4079.466292] [] ? >>>> btrfs_log_inode_parent+0xc61/0xf30 >>>> [btrfs] >>>> [ 4079.474373] [] ? btrfs_log_dentry_safe+0x59/0x80 >>>> [btrfs] >>>> [ 4079.482161] [] ? btrfs_sync_file+0x20d/0x330 >>>> [btrfs] >>>> [ 4079.489558] [] ? do_fsync+0x4c/0x80 >>>> [ 4079.495300] [] ? SyS_fdatasync+0xa/0x10 >>>> [ 4079.501422] [] ? system_call_fastpath+0x16/0x1b >>>> >>>> [ 4079.508334] user-space-program D ffff88107fc30640 0 32021 1 >>>> 0x00000004 >>>> [ 4079.516226] ffff880eae8efbf8 0000000000000086 0000000000009000 >>>> ffff880eae8effd8 >>>> [ 4079.524513] ffff880eae8effd8 ffff881030279610 ffffffffa06ecb26 >>>> ffff88101a5d6138 >>>> [ 4079.532802] ffff880ebb671d88 ffff880eae8efc20 ffff880ebb671de8 >>>> ffff881030279610 >>>> [ 4079.541092] Call Trace: >>>> [ 4079.550642] [] ? btrfs_tree_lock+0x85/0x2f0 >>>> [btrfs] >>>> [ 4079.557941] [] ? wake_up_atomic_t+0x30/0x30 >>>> [ 4079.564463] [] ? btrfs_search_slot+0x79f/0xb10 >>>> [btrfs] >>>> [ 4079.572058] [] ? >>>> btrfs_truncate_inode_items+0x168/0xb90 [btrfs] >>>> [ 4079.580526] [] ? >>>> join_transaction.isra.15+0x1e/0x3a0 >>>> [btrfs] >>>> [ 4079.588701] [] ? start_transaction+0x8d/0x470 >>>> [btrfs] >>>> [ 4079.596196] [] ? block_rsv_add_bytes+0x16/0x50 >>>> [btrfs] >>>> [ 4079.603789] [] ? btrfs_truncate+0xe9/0x2e0 [btrfs] >>>> [ 4079.610994] [] ? btrfs_setattr+0x30b/0x410 [btrfs] >>>> [ 4079.618197] [] ? notify_change+0x1dc/0x680 >>>> [ 4079.624625] [] ? aa_path_perm+0xd4/0x160 >>>> [ 4079.630854] [] ? do_truncate+0x5b/0x90 >>>> [ 4079.636889] [] ? >>>> do_sys_ftruncate.constprop.15+0x10a/0x160 >>>> [ 4079.644869] [] ? SyS_fcntl+0x5b/0x570 >>>> [ 4079.650805] [] ? system_call_fastpath+0x16/0x1b >>>> >>>> [ 4080.410607] user-space-program D ffff88107fc70640 0 32028 12639 >>>> 0x00000004 >>>> [ 4080.418489] ffff880eaeccbbe0 0000000000000086 0000000000009000 >>>> ffff880eaeccbfd8 >>>> [ 4080.426778] ffff880eaeccbfd8 ffff880f317ef1e0 ffffffffa06ecb26 >>>> ffff88101a5d6138 >>>> [ 4080.435067] ffff880ef7e93928 ffff880f317ef1e0 ffff880eaeccbc08 >>>> ffff880f317ef1e0 >>>> [ 4080.443353] Call Trace: >>>> [ 4080.452920] [] ? btrfs_tree_read_lock+0xdd/0x190 >>>> [btrfs] >>>> [ 4080.460703] [] ? wake_up_atomic_t+0x30/0x30 >>>> [ 4080.467225] [] ? >>>> btrfs_read_lock_root_node+0x2b/0x40 >>>> [btrfs] >>>> [ 4080.475400] [] ? btrfs_search_slot+0x801/0xb10 >>>> [btrfs] >>>> [ 4080.482994] [] ? >>>> btrfs_clean_one_deleted_snapshot+0xe0/0xe0 [btrfs] >>>> [ 4080.491857] [] ? btrfs_lookup_inode+0x26/0x90 >>>> [btrfs] >>>> [ 4080.499353] [] ? kmem_cache_alloc+0xaf/0xc0 >>>> [ 4080.505879] [] ? btrfs_iget+0xd5/0x5d0 [btrfs] >>>> [ 4080.512696] [] ? btrfs_get_token_64+0x104/0x120 >>>> [btrfs] >>>> [ 4080.520387] [] ? >>>> btrfs_log_inode_parent+0xbdf/0xf30 >>>> [btrfs] >>>> [ 4080.528469] [] ? btrfs_log_dentry_safe+0x59/0x80 >>>> [btrfs] >>>> [ 4080.536258] [] ? btrfs_sync_file+0x20d/0x330 >>>> [btrfs] >>>> [ 4080.543657] [] ? do_fsync+0x4c/0x80 >>>> [ 4080.549399] [] ? SyS_fdatasync+0xa/0x10 >>>> [ 4080.555534] [] ? system_call_fastpath+0x16/0x1b >>>> >>>> Signed-off-by: Robbie Ko >>>> --- >>>> fs/btrfs/tree-log.c | 4 ++-- >>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c >>>> index ef9c55b..9913084 100644 >>>> --- a/fs/btrfs/tree-log.c >>>> +++ b/fs/btrfs/tree-log.c >>>> @@ -5213,6 +5213,7 @@ process_leaf: >>>> if (di_key.type == BTRFS_ROOT_ITEM_KEY) >>>> continue; >>>> >>>> + btrfs_release_path(path); >>>> di_inode = btrfs_iget(root->fs_info->sb, >>>> &di_key, >>>> root, NULL); >>>> if (IS_ERR(di_inode)) { >>>> @@ -5222,13 +5223,12 @@ process_leaf: >>>> >>>> if (btrfs_inode_in_log(di_inode, >>>> trans->transid)) >>>> { >>>> iput(di_inode); >>>> - continue; >>>> + break; >>> >>> >>> Why the break instead of continue? This seems totally unrelated to the >>> deadlock on a leaf/node and incorrect. >>> >>> thanks >>> >>>> } >>>> >>>> ctx->log_new_dentries = false; >>>> if (type == BTRFS_FT_DIR || type == >>>> BTRFS_FT_SYMLINK) >>>> log_mode = LOG_INODE_ALL; >>>> - btrfs_release_path(path); >>>> ret = btrfs_log_inode(trans, root, di_inode, >>>> log_mode, 0, LLONG_MAX, >>>> ctx); >>>> if (!ret && >>>> -- >>>> 1.9.1 >>>> >>>> -- >>>> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" >>>> in >>>> the body of a message to majordomo@vger.kernel.org >>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> >>> >>> >>> >>> -- >>> Filipe David Manana, >>> >>> "People will forget what you said, >>> people will forget what you did, >>> but people will never forget how you made them feel." > > -- Filipe David Manana, "People will forget what you said, people will forget what you did, but people will never forget how you made them feel."