From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757914AbdKOMdx (ORCPT ); Wed, 15 Nov 2017 07:33:53 -0500 Received: from mail.kernel.org ([198.145.29.99]:49286 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752171AbdKOMdp (ORCPT ); Wed, 15 Nov 2017 07:33:45 -0500 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 40DAF20C09 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=chao@kernel.org Subject: Re: [PATCH] f2fs: check sit bitmap under sentry_lock To: Chao Yu , jaegeuk@kernel.org Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org References: <20171113095439.49897-1-yuchao0@huawei.com> From: Chao Yu Message-ID: <126ac734-9ff4-8b27-ea0b-386f0caaff55@kernel.org> Date: Wed, 15 Nov 2017 20:33:34 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <20171113095439.49897-1-yuchao0@huawei.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jaegeuk, Please drop this patch first, as it still can trigger deadlock as below, sorry about this mistake. - f2fs_put_super - f2fs_wait_discard_bios - __issue_discard_cmd - lock(&dcc->cmd_lock); A - __check_sit_bitmap - down_read(&sit_i->sentry_lock) B - do_write_page - allocate_data_block - down_write(&sit_i->sentry_lock) B - locate_dirty_segment - lock(&dirty_i->seglist_lock) C - write_checkpoint - clear_prefree_segments - lock(&dirty_i->seglist_lock) C - f2fs_issue_discard - __issue_discard_async - __queue_discard_cmd - __update_discard_tree_range - lock(&dcc->cmd_lock) A Thanks, On 2017/11/13 17:54, Chao Yu wrote: > This patch protects sit bitmap accessing in __check_sit_bitmap with > sentry_lock, meanwhile, in allocate_data_block, f2fs_wait_discard_bio > will not access/update sit cache, let's exclude it from sentry_lock's > region.> > Signed-off-by: Chao Yu > --- > fs/f2fs/segment.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > index c117e0913f2a..464696b1612a 100644 > --- a/fs/f2fs/segment.c > +++ b/fs/f2fs/segment.c > @@ -894,6 +894,8 @@ void __check_sit_bitmap(struct f2fs_sb_info *sbi, > unsigned long offset, size, max_blocks = sbi->blocks_per_seg; > unsigned long *map; > > + down_read(&SIT_I(sbi)->sentry_lock); > + > while (blk < end) { > segno = GET_SEGNO(sbi, blk); > sentry = get_seg_entry(sbi, segno); > @@ -908,6 +910,8 @@ void __check_sit_bitmap(struct f2fs_sb_info *sbi, > f2fs_bug_on(sbi, offset != size); > blk = START_BLOCK(sbi, segno + 1); > } > + > + up_read(&SIT_I(sbi)->sentry_lock); > #endif > } > > @@ -2527,12 +2531,13 @@ void allocate_data_block(struct f2fs_sb_info *sbi, struct page *page, > down_read(&SM_I(sbi)->curseg_lock); > > mutex_lock(&curseg->curseg_mutex); > - down_write(&sit_i->sentry_lock); > > *new_blkaddr = NEXT_FREE_BLKADDR(sbi, curseg); > > f2fs_wait_discard_bio(sbi, *new_blkaddr); > > + down_write(&sit_i->sentry_lock); > + > /* > * __add_sum_entry should be resided under the curseg_mutex > * because, this function updates a summary entry in the >