From: Sarthak Kukreti <sarthakkukreti@chromium.org>
To: Dave Chinner <david@fromorbit.com>
Cc: "Darrick J. Wong" <djwong@kernel.org>,
Mike Snitzer <snitzer@kernel.org>,
dm-devel@redhat.com, linux-block@vger.kernel.org,
linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
"Theodore Ts'o" <tytso@mit.edu>,
"Michael S. Tsirkin" <mst@redhat.com>,
Jason Wang <jasowang@redhat.com>,
Bart Van Assche <bvanassche@google.com>,
Christoph Hellwig <hch@infradead.org>,
Andreas Dilger <adilger.kernel@dilger.ca>,
Daniil Lunev <dlunev@google.com>,
Stefan Hajnoczi <stefanha@redhat.com>,
Brian Foster <bfoster@redhat.com>,
Alasdair Kergon <agk@redhat.com>
Subject: Re: [PATCH v4 1/4] block: Introduce provisioning primitives
Date: Wed, 19 Apr 2023 17:53:58 -0700 [thread overview]
Message-ID: <CAG9=OMNYp+uY9VG5VVB=-cjFBJj5iXbsiNWN5KxMXtwnGDFfbw@mail.gmail.com> (raw)
In-Reply-To: <20230419232118.GL447837@dread.disaster.area>
On Wed, Apr 19, 2023 at 4:21 PM Dave Chinner <david@fromorbit.com> wrote:
>
> On Wed, Apr 19, 2023 at 10:26:02AM -0700, Darrick J. Wong wrote:
> > On Wed, Apr 19, 2023 at 12:17:34PM -0400, Mike Snitzer wrote:
> > > (And obviously needs fixing independent of this patchset)
> > >
> > > Shouldn't mkfs first check that the underlying storage supports
> > > REQ_OP_PROVISION by verifying
> > > /sys/block/<dev>/queue/provision_max_bytes exists and is not 0?
> > > (Just saying, we need to add new features more defensively.. you just
> > > made the case based on this scenario's implications alone)
> >
> > Not for fallocate -- for regular files, there's no way to check if the
> > filesystem actually supports the operation requested other than to try
> > it and see if it succeeds. We probably should've defined a DRY_RUN flag
> > for that purpose back when it was introduced.
>
> That ignores the fact that fallocate() was never intended to
> guarantee it will work in all contexts - it's an advisory interface
> at it's most basic level. If the call succeeds, then great, it does
> what is says on the box, but if it fails then it should have no
> visible effect on user data at all and the application still needs
> to perform whatever modification it needed done in some other way.
>
> IOWs, calling it one a block device without first checking if the
> block device supports that fallocate operation is exactly how it is
> supposed to be used. If the kernel can't handle this gracefully
> without corrupting data, then that's a kernel bug and not an
> application problem.
>
> > For fallocate calls to block devices, yes, the program can check the
> > queue limits in sysfs if fstat says the supplied path is a block device,
> > but I don't know that most programs are that thorough. The fallocate(1)
> > CLI program does not check.
>
> Right. fallocate() was intended to just do the right thing without
> the application having to jump thrown an unknown number of hoops to
> determine if fallocate() can be used or not in the context it is
> executing in. The kernel implementation is supposed to abstract all that
> context-dependent behaviour away from the application; all the
> application has to do is implement the fallocate() fast path and a
> single generic "do the right thing the slow way" fallback when the
> fallocate() method it called is not supported...
>
I added a separate commit[1] to fix this so that we only
truncate_bdev_range() iff we are in a supported de-allocate mode call.
Subsequently, the REQ_OP_PROVISION patch is a bit simpler when rebased
on top.
[1] https://www.spinics.net/lists/kernel/msg4765688.html
Best
Sarthak
> -Dave.
> --
> Dave Chinner
> david@fromorbit.com
next prev parent reply other threads:[~2023-04-20 0:54 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20221229071647.437095-1-sarthakkukreti@chromium.org>
2023-04-14 0:02 ` [PATCH v3 0/3] Introduce provisioning primitives for thinly provisioned storage Sarthak Kukreti
2023-04-14 0:02 ` [PATCH v3 1/3] block: Introduce provisioning primitives Sarthak Kukreti
2023-04-17 17:35 ` Brian Foster
2023-04-18 22:13 ` Sarthak Kukreti
2023-04-14 0:02 ` [PATCH v3 2/3] dm: Add support for block provisioning Sarthak Kukreti
[not found] ` <CAJ0trDbyqoKEDN4kzcdn+vWhx+hk6pTM4ndf-E02f3uT9YZ3Uw@mail.gmail.com>
2023-04-14 18:14 ` Mike Snitzer
2023-04-14 21:58 ` Mike Snitzer
2023-04-18 22:13 ` Sarthak Kukreti
2023-04-14 0:02 ` [PATCH v3 3/3] loop: Add support for provision requests Sarthak Kukreti
2023-04-18 22:12 ` [PATCH v4 0/4] Introduce provisioning primitives for thinly provisioned storage Sarthak Kukreti
2023-04-18 22:12 ` [PATCH v4 1/4] block: Introduce provisioning primitives Sarthak Kukreti
2023-04-18 22:43 ` Bart Van Assche
2023-04-20 17:41 ` Sarthak Kukreti
2023-04-19 15:36 ` [dm-devel] " Darrick J. Wong
2023-04-19 16:17 ` Mike Snitzer
2023-04-19 17:26 ` Darrick J. Wong
2023-04-19 23:21 ` Dave Chinner
2023-04-20 0:53 ` Sarthak Kukreti [this message]
2023-04-18 22:12 ` [PATCH v4 2/4] dm: Add block provisioning support Sarthak Kukreti
2023-04-18 22:12 ` [PATCH v4 3/4] dm-thin: Add REQ_OP_PROVISION support Sarthak Kukreti
2023-04-18 22:12 ` [PATCH v4 4/4] loop: Add support for provision requests Sarthak Kukreti
2023-04-20 0:48 ` [PATCH v5 0/5] Introduce block provisioning primitives Sarthak Kukreti
2023-04-20 0:48 ` [PATCH v5 1/5] block: Don't invalidate pagecache for invalid falloc modes Sarthak Kukreti
2023-04-20 1:22 ` Darrick J. Wong
2023-04-20 1:48 ` Sarthak Kukreti
2023-04-20 1:47 ` [PATCH v5-fix " Sarthak Kukreti
2023-04-20 16:20 ` Mike Snitzer
2023-04-20 17:28 ` Sarthak Kukreti
2023-04-20 18:17 ` Sarthak Kukreti
2023-04-20 18:15 ` Sarthak Kukreti
2023-04-24 15:54 ` [PATCH v5 " kernel test robot
2023-05-04 8:50 ` kernel test robot
2023-04-20 0:48 ` [PATCH v5 2/5] block: Introduce provisioning primitives Sarthak Kukreti
2023-04-20 0:48 ` [PATCH v5 3/5] dm: Add block provisioning support Sarthak Kukreti
2023-04-20 0:48 ` [PATCH v5 4/5] dm-thin: Add REQ_OP_PROVISION support Sarthak Kukreti
2023-05-01 19:15 ` Mike Snitzer
2023-05-06 6:32 ` Sarthak Kukreti
2023-04-20 0:48 ` [PATCH v5 5/5] loop: Add support for provision requests Sarthak Kukreti
2023-05-06 6:29 ` [PATCH v6 0/5] Introduce block provisioning primitives Sarthak Kukreti
2023-05-06 6:29 ` [PATCH v6 1/5] block: Don't invalidate pagecache for invalid falloc modes Sarthak Kukreti
2023-05-09 16:51 ` Mike Snitzer
2023-05-12 18:31 ` Darrick J. Wong
2023-05-06 6:29 ` [PATCH v6 2/5] block: Introduce provisioning primitives Sarthak Kukreti
2023-05-09 16:52 ` Mike Snitzer
2023-05-12 18:37 ` Darrick J. Wong
2023-05-15 21:55 ` Sarthak Kukreti
2023-05-06 6:29 ` [PATCH v6 3/5] dm: Add block provisioning support Sarthak Kukreti
2023-05-09 16:52 ` Mike Snitzer
2023-05-06 6:29 ` [PATCH v6 4/5] dm-thin: Add REQ_OP_PROVISION support Sarthak Kukreti
2023-05-09 16:58 ` Mike Snitzer
2023-05-11 20:03 ` Sarthak Kukreti
2023-05-12 14:34 ` Mike Snitzer
2023-05-12 17:32 ` Mike Snitzer
2023-05-15 21:19 ` Sarthak Kukreti
2023-05-06 6:29 ` [PATCH v6 5/5] loop: Add support for provision requests Sarthak Kukreti
2023-05-15 12:40 ` Brian Foster
2023-05-15 21:31 ` Sarthak Kukreti
2023-05-12 18:28 ` [PATCH v6 0/5] Introduce block provisioning primitives Darrick J. Wong
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