public inbox for [email protected]
 help / color / mirror / Atom feed
From: "[email protected]" <[email protected]>
To: Damien Le Moal <[email protected]>
Cc: Kanchan Joshi <[email protected]>,
	"[email protected]" <[email protected]>,
	"[email protected]" <[email protected]>,
	"[email protected]" <[email protected]>,
	"[email protected]" <[email protected]>,
	"[email protected]" <[email protected]>,
	"[email protected]" <[email protected]>,
	"[email protected]" <[email protected]>,
	"[email protected]" <[email protected]>,
	"[email protected]" <[email protected]>,
	"[email protected]" <[email protected]>
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: <[email protected]> (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, [email protected] wrote:
>> On 18.06.2020 07:39, Damien Le Moal wrote:
>>> On 2020/06/18 2:27, Kanchan Joshi wrote:
>>>> From: Selvakumar S <[email protected]>
>>>>
>>>> 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 <[email protected]>
>>>> Signed-off-by: Kanchan Joshi <[email protected]>
>>>> Signed-off-by: Nitesh Shetty <[email protected]>
>>>> Signed-off-by: Javier Gonzalez <[email protected]>
>>>> ---
>>>>  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


  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         ` [email protected]
2020-06-18  8:47           ` Damien Le Moal
2020-06-18  9:11             ` [email protected] [this message]
2020-06-19  9:41               ` [email protected]
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                             ` [email protected]
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                       ` [email protected]
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    [email protected] \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox