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Re: [Qemu-devel] [PATCH v2 3/4] block: convert crypto driver to bdrv_co_
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH v2 3/4] block: convert crypto driver to bdrv_co_preadv|pwritev |
Date: |
Thu, 31 Aug 2017 10:08:00 -0500 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 |
On 08/31/2017 06:05 AM, Daniel P. Berrange wrote:
> Make the crypto driver implement the bdrv_co_preadv|pwritev
> callbacks, and also use bdrv_co_preadv|pwritev for I/O
> with the protocol driver beneath.
>
> Signed-off-by: Daniel P. Berrange <address@hidden>
> ---
> block/crypto.c | 103
> +++++++++++++++++++++++++++++----------------------------
> 1 file changed, 53 insertions(+), 50 deletions(-)
>
> static coroutine_fn int
> -block_crypto_co_readv(BlockDriverState *bs, int64_t sector_num,
> - int remaining_sectors, QEMUIOVector *qiov)
> +block_crypto_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
> + QEMUIOVector *qiov, int flags)
> {
> BlockCrypto *crypto = bs->opaque;
> - int cur_nr_sectors; /* number of sectors in current iteration */
> + uint64_t cur_bytes; /* number of bytes in current iteration */
> uint64_t bytes_done = 0;
> uint8_t *cipher_data = NULL;
> QEMUIOVector hd_qiov;
> int ret = 0;
> - size_t payload_offset =
> - qcrypto_block_get_payload_offset(crypto->block) / BDRV_SECTOR_SIZE;
> + size_t payload_offset = qcrypto_block_get_payload_offset(crypto->block);
Pre-existing: is size_t the right type, or can we overflow a 64-bit
offset on a 32-bit host?
> + uint64_t sector_num = offset / BDRV_SECTOR_SIZE;
> +
> + assert((offset % BDRV_SECTOR_SIZE) == 0);
> + assert((bytes % BDRV_SECTOR_SIZE) == 0);
The osdep.h macros might be nicer than open-coding; furthermore, if
desired, you could shorten to:
assert(QEMU_IS_ALIGNED(offset | bytes, BDRV_SECTOR_SIZE));
>
> static coroutine_fn int
> -block_crypto_co_writev(BlockDriverState *bs, int64_t sector_num,
> - int remaining_sectors, QEMUIOVector *qiov)
> +block_crypto_co_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t
> bytes,
> + QEMUIOVector *qiov, int flags)
> {
Hmm - you don't set supported_write_flags. But presumably, if the
underlying BDS supports BDRV_REQUEST_FUA, then crypto can likewise
support that flag by passing it through to the underlying device after
encryption.
> BlockCrypto *crypto = bs->opaque;
> - int cur_nr_sectors; /* number of sectors in current iteration */
> + uint64_t cur_bytes; /* number of bytes in current iteration */
> uint64_t bytes_done = 0;
> uint8_t *cipher_data = NULL;
> QEMUIOVector hd_qiov;
> int ret = 0;
> - size_t payload_offset =
> - qcrypto_block_get_payload_offset(crypto->block) / BDRV_SECTOR_SIZE;
> + size_t payload_offset = qcrypto_block_get_payload_offset(crypto->block);
> + uint64_t sector_num = offset / BDRV_SECTOR_SIZE;
> +
> + assert((offset % BDRV_SECTOR_SIZE) == 0);
> + assert((bytes % BDRV_SECTOR_SIZE) == 0);
Same comment as for read.
> @@ -611,8 +613,9 @@ BlockDriver bdrv_crypto_luks = {
> .bdrv_truncate = block_crypto_truncate,
> .create_opts = &block_crypto_create_opts_luks,
>
> - .bdrv_co_readv = block_crypto_co_readv,
> - .bdrv_co_writev = block_crypto_co_writev,
> + .bdrv_refresh_limits = block_crypto_refresh_limits,
> + .bdrv_co_preadv = block_crypto_co_preadv,
> + .bdrv_co_pwritev = block_crypto_co_pwritev,
> .bdrv_getlength = block_crypto_getlength,
> .bdrv_get_info = block_crypto_get_info_luks,
> .bdrv_get_specific_info = block_crypto_get_specific_info_luks,
Looks weird when = isn't consistently aligned, but we use more than one
space. My preference is to just use one space everywhere, as adding a
longer name to the list doesn't require a mass re-format of all other
entries; but I'm not opposed when people like the aligned = for
legibility. So up to you if you do anything in response to my nit.
Reviewed-by: Eric Blake <address@hidden>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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