From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chao Yu Subject: Re: [PATCH] f2fs: fix wrong sum_page pointer in f2fs_gc Date: Mon, 24 Oct 2016 10:55:41 +0800 Message-ID: <039aa77c-a78a-2e56-71fd-a00c0edbb228@huawei.com> References: <20161012232304.6667-1-jaegeuk@kernel.org> <20161013171421.GA6363@jaegeuk> <3ed5607f-0fe6-02cb-8c95-782913e65b5b@kernel.org> <20161014165700.GA67182@jaegeuk> <3a96264b-b187-a5ce-2279-f9edd3748838@kernel.org> <20161023214035.GA63620@jaegeuk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from sog-mx-4.v43.ch3.sourceforge.com ([172.29.43.194] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1byVR1-0000ar-CP for linux-f2fs-devel@lists.sourceforge.net; Mon, 24 Oct 2016 02:56:23 +0000 Received: from szxga03-in.huawei.com ([119.145.14.66]) by sog-mx-4.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128) (Exim 4.76) id 1byVQw-00013U-Ut for linux-f2fs-devel@lists.sourceforge.net; Mon, 24 Oct 2016 02:56:23 +0000 In-Reply-To: <20161023214035.GA63620@jaegeuk> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net To: linux-f2fs-devel@lists.sourceforge.net On 2016/10/24 5:40, Jaegeuk Kim wrote: > On Sun, Oct 23, 2016 at 08:26:15PM +0800, Chao Yu wrote: >> On 2016/10/15 0:57, Jaegeuk Kim wrote: >>> On Fri, Oct 14, 2016 at 09:25:59PM +0800, Chao Yu wrote: >>>> On 2016/10/14 1:14, Jaegeuk Kim wrote: >>>>> On Thu, Oct 13, 2016 at 06:33:19PM +0800, Chao Yu wrote: >>>>>> Hi Jaegeuk, >>>>>> >>>>>> On 2016/10/13 7:23, Jaegeuk Kim wrote: >>>>>>> This patch fixes using a wrong pointer for sum_page in f2fs_gc. >>>>>>> >>>>>>> Signed-off-by: Jaegeuk Kim >>>>>>> --- >>>>>>> fs/f2fs/gc.c | 10 +++++----- >>>>>>> 1 file changed, 5 insertions(+), 5 deletions(-) >>>>>>> >>>>>>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c >>>>>>> index e48142f..9c18917 100644 >>>>>>> --- a/fs/f2fs/gc.c >>>>>>> +++ b/fs/f2fs/gc.c >>>>>>> @@ -854,16 +854,16 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi, >>>>>>> >>>>>>> for (segno = start_segno; segno < end_segno; segno++) { >>>>>>> >>>>>>> - if (get_valid_blocks(sbi, segno, 1) == 0 || >>>>>>> - unlikely(f2fs_cp_error(sbi))) >>>>>>> - goto next; >>>>>>> - >>>>>>> /* find segment summary of victim */ >>>>>>> sum_page = find_get_page(META_MAPPING(sbi), >>>>>>> GET_SUM_BLOCK(sbi, segno)); >>>>>>> - f2fs_bug_on(sbi, !PageUptodate(sum_page)); >>>>>>> f2fs_put_page(sum_page, 0); >>>>>>> >>>>>>> + if (get_valid_blocks(sbi, segno, 1) == 0 || >>>>>>> + !PageUptodate(sum_page) || >>>>>> >>>>>> Why uptodate flag of summary page can be cleared? someone truncates it? >>>>> >>>>> Well, it looks like no problem to remove this, since it will hit >>>>> f2fs_cp_error(). I just intended to handle the above f2fs_bug_on here. >>>> >>>> If summary page becomes non-uptodate, it seems there is a bug in vfs/mm/f2fs, >>>> why not keep it there to detect bug? >>> >>> I found that the above get_sum_page() loop can give a page which is not uptodate >>> caused by EIO. Then, we would get the above bug_on, if we move f2fs_cp_error() >>> case like this patch. >>> >>> Thoughts? >> >> Seems this patch has already been merged into linus' tree... > > Yup. > >> Anyway, I can understand why you remove f2fs_bug_on & add PageUptodate here, but >> why should we repositon below check? >> >> if (get_valid_blocks(sbi, segno, 1) == 0 || >> unlikely(f2fs_cp_error(sbi))) > > Given description, this fixes using wrong sum_page pointer by: > > next: > f2fs_put_page(sum_page, 0); That's right, I'm missing this reference. Thanks for the explanation. :) thanks, > > Thanks, > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, SlashDot.org! http://sdm.link/slashdot > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel > > ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot