From: Eric Biggers <ebiggers@kernel.org>
To: Chao Yu <chao@kernel.org>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>, Theodore Ts'o <tytso@mit.edu>,
linux-f2fs-devel@lists.sourceforge.net,
linux-fsdevel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH] f2fs: remove broken support for allocating DIO writes
Date: Fri, 20 Aug 2021 11:11:57 -0700 [thread overview]
Message-ID: <YR/wbenc0d3eMAjz@sol.localdomain> (raw)
In-Reply-To: <c4e5c71d-1652-7174-fa36-674fab4e61df@kernel.org>
On Fri, Aug 20, 2021 at 05:35:21PM +0800, Chao Yu wrote:
> > > > >
> > > > > Hmm, I'm still trying to deal with this as a corner case where the writes
> > > > > haven't completed due to an error. How about keeping the preallocated block
> > > > > offsets and releasing them if we get an error? Do we need to handle EIO right?
> > > >
> > > > What about the case that CP + SPO following DIO preallocation? User will
> > > > encounter uninitialized block after recovery.
> > >
> > > I think buffered writes as a workaround can expose the last unwritten block as
> > > well, if SPO happens right after block allocation. We may need to compromise
> > > at certain level?
> > >
> >
> > Freeing preallocated blocks on error would be better than nothing, although note
> > that the preallocated blocks may have filled an arbitrary sequence of holes --
> > so simply truncating past EOF would *not* be sufficient.
> >
> > But really filesystems need to be designed to never expose uninitialized data,
> > even if I/O errors or a sudden power failure occurs. It is unfortunate that
> > f2fs apparently wasn't designed with that goal in mind.
> >
> > In any case, I don't think we can proceed with any other f2fs direct I/O
> > improvements until this data leakage bug can be solved one way or another. If
> > my patch to remove support for allocating writes isn't acceptable and the
> > desired solution is going to require some more invasive f2fs surgery, are you or
> > Chao going to work on it? I'm not sure there's much I can do here.
>
> I may have time to take look into the implementation as I proposed above, maybe
> just enabling this in FSYNC_MODE_STRICT mode if user concerns unwritten data?
> thoughts?
>
What does this have to do with fsync?
- Eric
WARNING: multiple messages have this Message-ID (diff)
From: Eric Biggers <ebiggers@kernel.org>
To: Chao Yu <chao@kernel.org>
Cc: linux-fsdevel@vger.kernel.org, Jaegeuk Kim <jaegeuk@kernel.org>,
Theodore Ts'o <tytso@mit.edu>,
stable@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH] f2fs: remove broken support for allocating DIO writes
Date: Fri, 20 Aug 2021 11:11:57 -0700 [thread overview]
Message-ID: <YR/wbenc0d3eMAjz@sol.localdomain> (raw)
In-Reply-To: <c4e5c71d-1652-7174-fa36-674fab4e61df@kernel.org>
On Fri, Aug 20, 2021 at 05:35:21PM +0800, Chao Yu wrote:
> > > > >
> > > > > Hmm, I'm still trying to deal with this as a corner case where the writes
> > > > > haven't completed due to an error. How about keeping the preallocated block
> > > > > offsets and releasing them if we get an error? Do we need to handle EIO right?
> > > >
> > > > What about the case that CP + SPO following DIO preallocation? User will
> > > > encounter uninitialized block after recovery.
> > >
> > > I think buffered writes as a workaround can expose the last unwritten block as
> > > well, if SPO happens right after block allocation. We may need to compromise
> > > at certain level?
> > >
> >
> > Freeing preallocated blocks on error would be better than nothing, although note
> > that the preallocated blocks may have filled an arbitrary sequence of holes --
> > so simply truncating past EOF would *not* be sufficient.
> >
> > But really filesystems need to be designed to never expose uninitialized data,
> > even if I/O errors or a sudden power failure occurs. It is unfortunate that
> > f2fs apparently wasn't designed with that goal in mind.
> >
> > In any case, I don't think we can proceed with any other f2fs direct I/O
> > improvements until this data leakage bug can be solved one way or another. If
> > my patch to remove support for allocating writes isn't acceptable and the
> > desired solution is going to require some more invasive f2fs surgery, are you or
> > Chao going to work on it? I'm not sure there's much I can do here.
>
> I may have time to take look into the implementation as I proposed above, maybe
> just enabling this in FSYNC_MODE_STRICT mode if user concerns unwritten data?
> thoughts?
>
What does this have to do with fsync?
- Eric
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next prev parent reply other threads:[~2021-08-20 18:12 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-28 1:51 [f2fs-dev] [PATCH] f2fs: remove broken support for allocating DIO writes Eric Biggers
2021-07-28 1:51 ` Eric Biggers
2021-07-30 19:17 ` [f2fs-dev] " Eric Biggers
2021-07-30 19:17 ` Eric Biggers
2021-07-30 22:12 ` [f2fs-dev] " Jaegeuk Kim
2021-07-30 22:12 ` Jaegeuk Kim
2021-07-30 22:19 ` Eric Biggers
2021-07-30 22:19 ` [f2fs-dev] " Eric Biggers
2021-07-31 1:05 ` Jaegeuk Kim
2021-07-31 1:05 ` [f2fs-dev] " Jaegeuk Kim
2021-07-31 1:18 ` Eric Biggers
2021-07-31 1:18 ` Eric Biggers
2021-07-31 2:46 ` Theodore Ts'o
2021-07-31 2:46 ` [f2fs-dev] " Theodore Ts'o
2021-08-02 4:39 ` Eric Biggers
2021-08-02 4:39 ` Eric Biggers
2021-08-02 9:00 ` Chao Yu
2021-08-02 9:00 ` [f2fs-dev] " Chao Yu
2021-08-02 18:23 ` Jaegeuk Kim
2021-08-02 18:23 ` Jaegeuk Kim
2021-08-03 1:19 ` [f2fs-dev] " Chao Yu
2021-08-03 1:19 ` Chao Yu
2021-08-03 1:34 ` [f2fs-dev] " Jaegeuk Kim
2021-08-03 1:34 ` Jaegeuk Kim
2021-08-17 2:03 ` [f2fs-dev] " Eric Biggers
2021-08-17 2:03 ` Eric Biggers
2021-08-17 5:42 ` [f2fs-dev] " Christoph Hellwig
2021-08-17 5:42 ` Christoph Hellwig
2021-08-17 18:57 ` Jaegeuk Kim
2021-08-17 18:57 ` [f2fs-dev] " Jaegeuk Kim
2021-08-17 20:27 ` Eric Biggers
2021-08-17 20:27 ` [f2fs-dev] " Eric Biggers
2021-08-17 21:33 ` Jaegeuk Kim
2021-08-17 21:33 ` Jaegeuk Kim
2021-08-18 0:06 ` [f2fs-dev] " Eric Biggers
2021-08-18 0:06 ` Eric Biggers
2021-08-20 9:35 ` Chao Yu
2021-08-20 9:35 ` [f2fs-dev] " Chao Yu
2021-08-20 18:11 ` Eric Biggers [this message]
2021-08-20 18:11 ` Eric Biggers
2021-08-20 22:01 ` [f2fs-dev] " Chao Yu
2021-08-20 22:01 ` Chao Yu
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