From: Satya Tangirala via Linux-f2fs-devel <linux-f2fs-devel@lists.sourceforge.net>
To: Christoph Hellwig <hch@infradead.org>
Cc: linux-block@vger.kernel.org, linux-scsi@vger.kernel.org,
Kim Boojin <boojin.kim@samsung.com>,
Kuohong Wang <kuohong.wang@mediatek.com>,
Barani Muthukumaran <bmuthuku@qti.qualcomm.com>,
linux-f2fs-devel@lists.sourceforge.net,
Eric Biggers <ebiggers@kernel.org>,
linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [f2fs-dev] [PATCH v6 0/9] Inline Encryption Support
Date: Fri, 21 Feb 2020 04:30:30 -0800 [thread overview]
Message-ID: <20200221123030.GA253045@google.com> (raw)
In-Reply-To: <20200205180541.GA32041@infradead.org>
Hi Christoph,
I sent out v7 of the patch series. It's at
https://lore.kernel.org/linux-fscrypt/20200221115050.238976-1-satyat@google.com/T/#t
It manages keyslots on a per-request basis now - I made it get keyslots
in blk_mq_get_request, because that way I wouldn't have to worry about
programming keys in an atomic context. What do you think of the new
approach?
On Wed, Feb 05, 2020 at 10:05:41AM -0800, Christoph Hellwig wrote:
> On Tue, Feb 04, 2020 at 11:36:01PM -0800, Eric Biggers wrote:
> > The vendor-specific SMC calls do seem to work in atomic context, at least on
> > SDA845. However, in ufshcd_program_key(), the calls to pm_runtime_get_sync()
> > and ufshcd_hold() can also sleep.
> >
> > I think we can move the pm_runtime_get_sync() to ufshcd_crypto_keyslot_evict(),
> > since the block layer already ensures the device is not runtime-suspended while
> > requests are being processed (see blk_queue_enter()). I.e., keyslots can be
> > evicted independently of any bio, but that's not the case for programming them.
>
> Yes.
>
> > That still leaves ufshcd_hold(), which is still needed to ungate the UFS clocks.
> > It does accept an 'async' argument, which is used by ufshcd_queuecommand() to
> > schedule work to ungate the clocks and return SCSI_MLQUEUE_HOST_BUSY.
> >
> > So in blk_mq_dispatch_rq_list(), we could potentially try to acquire the
> > keyslot, and if it can't be done because either none are available or because
> > something else needs to be waited for, we can put the request back on the
> > dispatch list -- similar to how failure to get a driver tag is handled.
>
> Yes, that is what I had in mind.
>
> > However, if I understand correctly, that would mean that all requests to the
> > same hardware queue would be blocked whenever someone is waiting for a keyslot
> > -- even unencrypted requests and requests for unrelated keyslots.
>
> At least for an initial dumb implementation, yes. But if we care enough
> we can improve the code to check for the encrypted flag and only put
> back encrypted flags in that case.
>
> > It's possible that would still be fine for the Android use case, as vendors tend
> > to add enough keyslots to work with Android, provided that they choose the
> > fscrypt format that uses one key per encryption policy rather than one key per
> > file. I.e., it might be the case that no one waits for keyslots in practice
> > anyway. But, it seems it would be undesirable for a general Linux kernel
> > framework, which could potentially be used with per-file keys or with hardware
> > that only has a *very* small number of keyslots.
> >
> > Another option would be to allocate the keyslot in blk_mq_get_request(), where
> > sleeping is still allowed, but some merging was already done.
>
> That is another good idea. In blk_mq_get_request we acquire other
> resources like the tag, so this would be a very logical places to
> acquire the key slots. We can should also be able to still merge into
> the request while it is waiting.
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next prev parent reply other threads:[~2020-02-21 12:35 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-18 14:51 [f2fs-dev] [PATCH v6 0/9] Inline Encryption Support Satya Tangirala via Linux-f2fs-devel
2019-12-18 14:51 ` [f2fs-dev] [PATCH v6 1/9] block: Keyslot Manager for Inline Encryption Satya Tangirala via Linux-f2fs-devel
2019-12-18 20:13 ` Eric Biggers
2020-01-17 9:10 ` Christoph Hellwig
2019-12-18 14:51 ` [f2fs-dev] [PATCH v6 2/9] block: Add encryption context to struct bio Satya Tangirala via Linux-f2fs-devel
2019-12-18 21:10 ` Eric Biggers
2019-12-18 21:21 ` Darrick J. Wong
2019-12-18 21:25 ` Martin K. Petersen
2019-12-18 22:27 ` Eric Biggers
2019-12-19 0:47 ` Martin K. Petersen
2019-12-20 3:52 ` Eric Biggers
2020-01-07 4:35 ` Martin K. Petersen
2020-01-08 14:07 ` Christoph Hellwig
2020-01-08 17:26 ` Eric Biggers
2020-01-17 8:32 ` Christoph Hellwig
2020-01-18 5:11 ` Eric Biggers
2020-01-21 22:05 ` Satya Tangirala via Linux-f2fs-devel
2020-01-09 3:40 ` Martin K. Petersen
2020-01-14 21:24 ` Eric Biggers
2019-12-18 14:51 ` [f2fs-dev] [PATCH v6 3/9] block: blk-crypto for Inline Encryption Satya Tangirala via Linux-f2fs-devel
2019-12-20 3:14 ` Eric Biggers
2019-12-20 5:10 ` Eric Biggers
2020-01-14 21:22 ` Eric Biggers
2019-12-18 14:51 ` [f2fs-dev] [PATCH v6 4/9] scsi: ufs: UFS driver v2.1 spec crypto additions Satya Tangirala via Linux-f2fs-devel
2020-01-17 12:31 ` Christoph Hellwig
2019-12-18 14:51 ` [f2fs-dev] [PATCH v6 5/9] scsi: ufs: UFS crypto API Satya Tangirala via Linux-f2fs-devel
2019-12-20 4:48 ` Eric Biggers
2020-01-14 21:16 ` Eric Biggers
2020-01-17 13:51 ` Christoph Hellwig
2019-12-18 14:51 ` [f2fs-dev] [PATCH v6 6/9] scsi: ufs: Add inline encryption support to UFS Satya Tangirala via Linux-f2fs-devel
2019-12-20 5:44 ` Eric Biggers
2020-01-17 13:58 ` Christoph Hellwig
2020-01-18 5:27 ` Eric Biggers
2020-02-05 18:07 ` Christoph Hellwig
2020-01-18 3:58 ` Eric Biggers
2020-02-05 20:47 ` Eric Biggers
2019-12-18 14:51 ` [f2fs-dev] [PATCH v6 7/9] fscrypt: add inline encryption support Satya Tangirala via Linux-f2fs-devel
2020-01-14 21:12 ` Eric Biggers
2019-12-18 14:51 ` [f2fs-dev] [PATCH v6 8/9] f2fs: " Satya Tangirala via Linux-f2fs-devel
2019-12-20 4:23 ` Eric Biggers
2019-12-18 14:51 ` [f2fs-dev] [PATCH v6 9/9] ext4: " Satya Tangirala via Linux-f2fs-devel
2019-12-19 0:12 ` Eric Biggers
2019-12-19 0:31 ` Satya Tangirala via Linux-f2fs-devel
2019-12-22 0:16 ` Eric Biggers
2020-01-08 14:05 ` [f2fs-dev] [PATCH v6 0/9] Inline Encryption Support Christoph Hellwig
2020-01-08 18:43 ` Satya Tangirala via Linux-f2fs-devel
2020-01-17 8:52 ` Christoph Hellwig
2020-02-01 0:53 ` Satya Tangirala via Linux-f2fs-devel
2020-02-03 9:15 ` Christoph Hellwig
2020-02-04 3:39 ` Satya Tangirala via Linux-f2fs-devel
2020-02-04 14:58 ` Christoph Hellwig
2020-02-04 21:21 ` Eric Biggers
2020-02-05 7:36 ` Eric Biggers
2020-02-05 18:05 ` Christoph Hellwig
2020-02-21 12:30 ` Satya Tangirala via Linux-f2fs-devel [this message]
2020-02-21 14:20 ` Christoph Hellwig
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