linux-kernel - Re: [f2fs-dev] [PATCH] f2fs: fix race of pending

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Message-ID: <CACOAw_wfew8xER-CibUtddRKVtcr3k_iGzjQ-bVYxqRUuEVCcw@mail.gmail.com>
Date:   Fri, 4 Dec 2020 16:01:54 +0900
From:   Daeho Jeong <daeho43@...il.com>
To:     Eric Biggers <ebiggers@...nel.org>
Cc:     linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net, kernel-team@...roid.com,
        Daeho Jeong <daehojeong@...gle.com>
Subject: Re: [f2fs-dev] [PATCH] f2fs: fix race of pending_pages in decompression

Thanks for the explanation about verity.
I got your point. Thanks~

2020년 12월 4일 (금) 오후 2:18, Eric Biggers <ebiggers@...nel.org>님이 작성:
>
> On Fri, Dec 04, 2020 at 02:00:34PM +0900, Daeho Jeong wrote:
> > I think I don't understand how verity works.
> > Right after verity is enabled on a file, is the verity logic working
> > for the whole file data area?
> > Or it's just working for the data area which is updated after verity is enabled?
> >
>
> It's for the whole file.
>
> My point is just that if there is a bio that saw that verity isn't enabled yet
> when it started and therefore STEP_VERITY didn't get set in the
> bio_post_read_ctx (or the bio_post_read_ctx didn't get allocated due to one not
> being needed), then the filesystem shouldn't change its mind and try to verify
> the pages when the bio completes if verity happened to be enabled concurrently.
> It's too late for that bio.
>
> - Eric