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From: Eric Biggers <ebiggers@kernel.org>
To: Satya Tangirala <satyat@google.com>
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCH v3 00/10] ensure bios aren't split in middle of crypto data unit
Date: Wed, 16 Jun 2021 20:51:01 -0700	[thread overview]
Message-ID: <YMrGpfXYtGmvtSsO@sol.localdomain> (raw)
In-Reply-To: <20210604195900.2096121-1-satyat@google.com>

On Fri, Jun 04, 2021 at 07:58:50PM +0000, Satya Tangirala wrote:
> When a bio has an encryption context, its size must be aligned to its
> crypto data unit size. A bio must not be split in the middle of a data
> unit. Currently, bios are split at logical block boundaries, but a crypto
> data unit size might be larger than the logical block size - e.g. a machine
> could be using fscrypt (which uses 4K crypto data units) with an eMMC block
> device with inline encryption hardware that has a logical block size of 512
> bytes. So we need to support cases where the data unit size is larger than
> the logical block size.

It's worth explaining the motivation for this more clearly.  Currently the only
user of blk-crypto is fscrypt (on ext4 and f2fs), which (currently) only submits
bios where the size of each segment is a multiple of data_unit_size.  That
happens to avoid most of the cases where bios could be split in the middle of a
data unit.  However, when support for direct I/O on encrypted files is added, or
when support for filesystem metadata encryption is added, it will be possible
for bios to have segment lengths that are only multiples of the logical block
size.  So the block layer needs to start handling this case appropriately.

- Eric

      parent reply	other threads:[~2021-06-17  3:51 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-04 19:58 Satya Tangirala
2021-06-04 19:58 ` [PATCH v3 01/10] block: introduce blk_ksm_is_empty() Satya Tangirala
2021-06-16 23:47   ` Eric Biggers
2021-06-04 19:58 ` [PATCH v3 02/10] block: blk-crypto: introduce blk_crypto_bio_sectors_alignment() Satya Tangirala
2021-06-17  0:29   ` Eric Biggers
2021-06-04 19:58 ` [PATCH v3 03/10] block: introduce bio_required_sector_alignment() Satya Tangirala
2021-06-17  0:37   ` Eric Biggers
2021-06-04 19:58 ` [PATCH v3 04/10] block: respect bio_required_sector_alignment() in blk-crypto-fallback Satya Tangirala
2021-06-17  0:39   ` Eric Biggers
2021-06-17  4:34     ` Eric Biggers
2021-06-04 19:58 ` [PATCH v3 05/10] block: keyslot-manager: introduce blk_ksm_restrict_dus_to_queue_limits() Satya Tangirala
2021-06-17  1:58   ` Eric Biggers
2021-06-04 19:58 ` [PATCH v3 06/10] ufshcd: handle error from blk_ksm_register() Satya Tangirala
2021-06-04 19:58 ` [PATCH v3 07/10] mmc: " Satya Tangirala
2021-06-17  3:25   ` Eric Biggers
2021-06-24 10:04     ` Satya Tangirala
2021-06-04 19:58 ` [PATCH v3 08/10] dm: " Satya Tangirala
2021-06-17  3:23   ` Eric Biggers
2021-06-04 19:58 ` [PATCH v3 09/10] blk-merge: Ensure bios aren't split in middle of a crypto data unit Satya Tangirala
2021-06-04 19:59 ` [PATCH v3 10/10] block: add WARN_ON_ONCE() to bio_split() for sector alignment Satya Tangirala
2021-06-17  2:46   ` Eric Biggers
2021-06-17  3:51 ` Eric Biggers [this message]

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