From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Authentication-Results: smtp.codeaurora.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="ryuJRDEY" DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 981F7601A8 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932380AbeFFP4P (ORCPT + 25 others); Wed, 6 Jun 2018 11:56:15 -0400 Received: from mail.kernel.org ([198.145.29.99]:53530 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752677AbeFFP4K (ORCPT ); Wed, 6 Jun 2018 11:56:10 -0400 Message-ID: <81a365a631279f8b0ad0ed71b222c19817045704.camel@kernel.org> Subject: Re: [PATCH 2/5] buffer: record blockdev write errors in super_block that backs them From: Jeff Layton To: viro@ZenIV.linux.org.uk, dhowells@redhat.com, Jens Axboe Cc: willy@infradead.org, andres@anarazel.de, cmaiolino@redhat.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, "linux-block@vger.kernel.org" Date: Wed, 06 Jun 2018 11:56:06 -0400 In-Reply-To: <20180604180304.9662-3-jlayton@kernel.org> References: <20180604180304.9662-1-jlayton@kernel.org> <20180604180304.9662-3-jlayton@kernel.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.2 (3.28.2-1.fc28) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2018-06-04 at 14:03 -0400, Jeff Layton wrote: > From: Jeff Layton > > When syncing out a block device (a'la __sync_blockdev), any error > encountered will only be recorded in the bd_inode's mapping. When the > blockdev contains a filesystem however, we'd like to also record the > error in the super_block that's stored there. > > Make mark_buffer_write_io_error also record the error in the > corresponding super_block when a writeback error occurs and the block > device contains a mounted superblock. > > Signed-off-by: Jeff Layton > --- > fs/buffer.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/fs/buffer.c b/fs/buffer.c > index 249b83fafe48..dae2a857d5bc 100644 > --- a/fs/buffer.c > +++ b/fs/buffer.c > @@ -1117,6 +1117,8 @@ void mark_buffer_write_io_error(struct buffer_head *bh) > mapping_set_error(bh->b_page->mapping, -EIO); > if (bh->b_assoc_map) > mapping_set_error(bh->b_assoc_map, -EIO); > + if (bh->b_bdev->bd_super) > + errseq_set(&bh->b_bdev->bd_super->s_wb_err, -EIO); > } > EXPORT_SYMBOL(mark_buffer_write_io_error); > (cc'ing linux-block and Jens) I'm wondering whether this patch might turn out to be racy. For instance, could a call to __sync_blockdev race with an unmount in such a way that bd_super goes NULL after we check it but before errseq_set is called? If so, what can we do to ensure that that doesn't happen? Any insight here would be appreciated. Thanks, -- Jeff Layton