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

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Date:   Fri, 4 Dec 2020 13:48:24 +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

Eric,

I have another question.
I understand enabling the verity can be possible in the middle of I/O.
Is the opposite way also possible? Actually, I couldn't find any
disabling function of it, though.

2020년 12월 4일 (금) 오후 1:31, Daeho Jeong <daeho43@...il.com>님이 작성:
>
> > Are you sure?  I thought that compression (and encryption) apply to the whole
> > file, including any Merkle tree blocks past i_size.
>
> This "dic" structure is only for "de"compression, so we don't need to
> worry about going beyond i_size case.
>
> > Also, even if you include the i_size check, it's still wrong to check
> > fsverity_active() in the middle of the I/O because FS_IOC_ENABLE_VERITY can
> > execute concurrently, causing fsverity_active() to return false at the beginning
> > of the I/O and true later in the I/O.  It needs to be checked only once, at the
> > beginning...
>
> Got it. Our previous implementation didn't consider this case. Need to fix this.
>
> Thanks,