linux-kernel - Re: [PATCH v2] fs: global sync to not clear error status of individual inodes

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Wed, 16 Sep 2015 13:47:15 -0400
From:	Tejun Heo <tj@...nel.org>
To:	Junichi Nomura <j-nomura@...jp.nec.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"andi@...stfloor.org" <andi@...stfloor.org>,
	"fengguang.wu@...el.com" <fengguang.wu@...el.com>,
	"tony.luck@...el.com" <tony.luck@...el.com>,
	"david@...morbit.com" <david@...morbit.com>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Subject: Re: [PATCH v2] fs: global sync to not clear error status of
 individual inodes

On Wed, Sep 16, 2015 at 08:39:09AM +0000, Junichi Nomura wrote:
> filemap_fdatawait() is a function to wait for on-going writeback
> to complete but also consume and clear error status of the mapping
> set during writeback.
> The latter functionality is critical for applications to detect
> writeback error with system calls like fsync(2)/fdatasync(2).
> 
> However filemap_fdatawait() is also used by sync(2) or FIFREEZE
> ioctl, which don't check error status of individual mappings.
> 
> As a result, fsync() may not be able to detect writeback error
> if events happen in the following order:
> 
>    Application                    System admin
>    ----------------------------------------------------------
>    write data on page cache
>                                   Run sync command
>                                   writeback completes with error
>                                   filemap_fdatawait() clears error
>    fsync returns success
>    (but the data is not on disk)
> 
> This patch adds filemap_fdatawait_keep_errors() for call sites where
> writeback error is not handled so that they don't clear error status.
> 
> Signed-off-by: Jun'ichi Nomura <j-nomura@...jp.nec.com>
> Acked-by: Andi Kleen <ak@...ux.intel.com>

Reviewed-by: Tejun Heo <tj@...nel.org>

Thanks.

-- 
tejun
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/