From: "javier.gonz@samsung.com" <javier@javigon.com>
To: Damien Le Moal <Damien.LeMoal@wdc.com>
Cc: Kanchan Joshi <joshi.k@samsung.com>,
"axboe@kernel.dk" <axboe@kernel.dk>,
"viro@zeniv.linux.org.uk" <viro@zeniv.linux.org.uk>,
"bcrl@kvack.org" <bcrl@kvack.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-aio@kvack.org" <linux-aio@kvack.org>,
"io-uring@vger.kernel.org" <io-uring@vger.kernel.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"selvakuma.s1@samsung.com" <selvakuma.s1@samsung.com>,
"nj.shetty@samsung.com" <nj.shetty@samsung.com>
Subject: Re: [PATCH 3/3] io_uring: add support for zone-append
Date: Thu, 18 Jun 2020 11:11:13 +0200 [thread overview]
Message-ID: <20200618091113.eu2xdp6zmdooy5d2@mpHalley.local> (raw)
In-Reply-To: <CY4PR04MB3751D5D6AFB0DA7B8A2DFF61E79B0@CY4PR04MB3751.namprd04.prod.outlook.com>
On 18.06.2020 08:47, Damien Le Moal wrote:
>On 2020/06/18 17:35, javier.gonz@samsung.com wrote:
>> On 18.06.2020 07:39, Damien Le Moal wrote:
>>> On 2020/06/18 2:27, Kanchan Joshi wrote:
>>>> From: Selvakumar S <selvakuma.s1@samsung.com>
>>>>
>>>> Introduce three new opcodes for zone-append -
>>>>
>>>> IORING_OP_ZONE_APPEND : non-vectord, similiar to IORING_OP_WRITE
>>>> IORING_OP_ZONE_APPENDV : vectored, similar to IORING_OP_WRITEV
>>>> IORING_OP_ZONE_APPEND_FIXED : append using fixed-buffers
>>>>
>>>> Repurpose cqe->flags to return zone-relative offset.
>>>>
>>>> Signed-off-by: SelvaKumar S <selvakuma.s1@samsung.com>
>>>> Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
>>>> Signed-off-by: Nitesh Shetty <nj.shetty@samsung.com>
>>>> Signed-off-by: Javier Gonzalez <javier.gonz@samsung.com>
>>>> ---
>>>> fs/io_uring.c | 72 +++++++++++++++++++++++++++++++++++++++++--
>>>> include/uapi/linux/io_uring.h | 8 ++++-
>>>> 2 files changed, 77 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>>>> index 155f3d8..c14c873 100644
>>>> --- a/fs/io_uring.c
>>>> +++ b/fs/io_uring.c
>>>> @@ -649,6 +649,10 @@ struct io_kiocb {
>>>> unsigned long fsize;
>>>> u64 user_data;
>>>> u32 result;
>>>> +#ifdef CONFIG_BLK_DEV_ZONED
>>>> + /* zone-relative offset for append, in bytes */
>>>> + u32 append_offset;
>>>
>>> this can overflow. u64 is needed.
>>
>> We chose to do it this way to start with because struct io_uring_cqe
>> only has space for u32 when we reuse the flags.
>>
>> We can of course create a new cqe structure, but that will come with
>> larger changes to io_uring for supporting append.
>>
>> Do you believe this is a better approach?
>
>The problem is that zone size are 32 bits in the kernel, as a number of sectors.
>So any device that has a zone size smaller or equal to 2^31 512B sectors can be
>accepted. Using a zone relative offset in bytes for returning zone append result
>is OK-ish, but to match the kernel supported range of possible zone size, you
>need 31+9 bits... 32 does not cut it.
Agree. Our initial assumption was that u32 would cover current zone size
requirements, but if this is a no-go, we will take the longer path.
>
>Since you need a 64-bit sized result, I would also prefer that you drop the zone
>relative offset as a result and return the absolute offset instead. That makes
>life easier for the applications since the zone append requests also must use
>absolute offsets for zone start. An absolute offset as a result becomes
>consistent with that and all other read/write system calls that all use absolute
>offsets (seek() is the only one that I know of that can use a relative offset,
>but that is not an IO system call).
Agree. Using relative offsets was a product of reusing the existing u32.
If we move to u64, there is no need to do an extra transformation.
Thanks Damien!
Javier
next prev parent reply other threads:[~2020-06-18 9:11 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20200617172653epcas5p488de50090415eb802e62acc0e23d8812@epcas5p4.samsung.com>
2020-06-17 17:23 ` [PATCH 0/3] zone-append support in aio and io-uring Kanchan Joshi
[not found] ` <CGME20200617172702epcas5p4dbf4729d31d9a85ab1d261d04f238e61@epcas5p4.samsung.com>
2020-06-17 17:23 ` [PATCH 1/3] fs,block: Introduce IOCB_ZONE_APPEND and direct-io handling Kanchan Joshi
2020-06-17 19:02 ` Pavel Begunkov
2020-06-18 7:16 ` Damien Le Moal
2020-06-18 18:35 ` Kanchan Joshi
[not found] ` <CGME20200617172706epcas5p4dcbc164063f58bad95b211b9d6dfbfa9@epcas5p4.samsung.com>
2020-06-17 17:23 ` [PATCH 2/3] aio: add support for zone-append Kanchan Joshi
2020-06-18 7:33 ` Damien Le Moal
[not found] ` <CGME20200617172713epcas5p352f2907a12bd4ee3c97be1c7d8e1569e@epcas5p3.samsung.com>
2020-06-17 17:23 ` [PATCH 3/3] io_uring: " Kanchan Joshi
2020-06-17 18:55 ` Pavel Begunkov
2020-06-18 7:39 ` Damien Le Moal
2020-06-18 8:35 ` javier.gonz@samsung.com
2020-06-18 8:47 ` Damien Le Moal
2020-06-18 9:11 ` javier.gonz@samsung.com [this message]
2020-06-19 9:41 ` javier.gonz@samsung.com
2020-06-19 11:15 ` Matias Bjørling
2020-06-19 14:18 ` Jens Axboe
2020-06-19 15:14 ` Matias Bjørling
2020-06-19 15:20 ` Jens Axboe
2020-06-19 15:40 ` Matias Bjørling
2020-06-19 15:44 ` Jens Axboe
2020-06-21 18:55 ` javier.gonz@samsung.com
2020-06-19 14:15 ` Jens Axboe
2020-06-19 14:59 ` Pavel Begunkov
2020-06-19 15:02 ` Jens Axboe
2020-06-21 18:52 ` javier.gonz@samsung.com
2020-06-17 17:42 ` [PATCH 0/3] zone-append support in aio and io-uring Matthew Wilcox
2020-06-18 6:56 ` Christoph Hellwig
2020-06-18 8:29 ` Javier González
2020-06-18 17:52 ` Kanchan Joshi
2020-06-19 3:08 ` Damien Le Moal
2020-06-19 7:56 ` Christoph Hellwig
2020-06-18 8:04 ` Matias Bjørling
2020-06-18 8:27 ` Javier González
2020-06-18 8:32 ` Matias Bjørling
2020-06-18 8:39 ` Javier González
2020-06-18 8:46 ` Matias Bjørling
2020-06-18 14:16 ` Christoph Hellwig
2020-06-18 19:21 ` Kanchan Joshi
2020-06-18 20:04 ` Matias Bjørling
2020-06-19 1:03 ` Damien Le Moal
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