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From: Vladislav Shpilevoy <v.shpilevoy@tarantool.org>
To: Cyrill Gorcunov <gorcunov@gmail.com>,
	tml <tarantool-patches@dev.tarantool.org>
Subject: Re: [Tarantool-patches] [PATCH] fio/coio: handle partial writes
Date: Wed, 10 Jun 2020 00:55:04 +0200	[thread overview]
Message-ID: <cba903ec-3032-fae2-21da-41a39468a16e@tarantool.org> (raw)
In-Reply-To: <20200421213930.28713-1-gorcunov@gmail.com>

Hi! Thanks for the patch!

See 4 comments below.

On 21/04/2020 23:39, Cyrill Gorcunov wrote:
> Writting less bytes than requested is perfectly fine.

1. 'Writting' -> 'Writing'.

> In turn our fio.write/pwrite api simply returns 'true'
> even if only some part of a buffer has been written.
> 
> Thus make coio_write and coio_pwrite to write the
> whole data in a cycle. Note in most situations there
> will be only one pass, partial writes are really the
> rare cases.
> 
> Fixes #4651
> 
> Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
> ---
> issue https://github.com/tarantool/tarantool/issues/4651
> branch gorcunov/gh-4651-partial-write
> 
>  src/lib/core/coio_file.c | 62 ++++++++++++++++++++++++++++------
>  src/lib/core/errinj.h    |  1 +
>  test/app/fio.result      | 73 ++++++++++++++++++++++++++++++++++++++++
>  test/app/fio.test.lua    | 21 ++++++++++++
>  test/box/errinj.result   |  1 +
>  5 files changed, 147 insertions(+), 11 deletions(-)
> 
> diff --git a/src/lib/core/coio_file.c b/src/lib/core/coio_file.c
> index e2345567c..e290214bc 100644
> --- a/src/lib/core/coio_file.c
> +++ b/src/lib/core/coio_file.c
> @@ -164,10 +164,30 @@ coio_file_close(int fd)
>  ssize_t
>  coio_pwrite(int fd, const void *buf, size_t count, off_t offset)
>  {
> -	INIT_COEIO_FILE(eio);
> -	eio_req *req = eio_write(fd, (void *) buf, count, offset,
> -				 0, coio_complete, &eio);
> -	return coio_wait_done(req, &eio);
> +	ssize_t left = count, pos = 0, res, chunk;
> +	eio_req *req;
> +
> +	while (left > 0) {
> +		INIT_COEIO_FILE(eio);
> +		chunk = left;
> +
> +		ERROR_INJECT(ERRINJ_COIO_WRITE_CHUNK, {
> +			chunk = 1;
> +		});
> +
> +		req = eio_write(fd, (void *)buf + pos, chunk,

2. As it was fairly noticed by Timur in one of my
patches for lsregion - lets better avoid 'void' pointer
arithmetic. And use uint8_t * or char *.

> +				offset + pos, EIO_PRI_DEFAULT,
> +				coio_complete, &eio);
> +		res = coio_wait_done(req, &eio);
> +		if (res < 0) {
> +			pos = -1;

3. What if eio_write() returns EAGAIN/EINTR/WOULDBLOCK? Can it
happen at all? Can it happen, if the descriptor is not
blocking? Can it happen if the underlying FS is a network
file system, like sshfs via FUSE?

Coio socket library handles these errors and retries them.

> +			break;
> +		} else {
> +			left -= res;
> +			pos += res;
> +		}
> +	}
> +	return pos;
>  }
> diff --git a/test/app/fio.result b/test/app/fio.result
> index 783fa4fab..73fbd29e5 100644
> --- a/test/app/fio.result
> +++ b/test/app/fio.result
> @@ -865,6 +871,73 @@ fh6:close()
>  ---
>  - true
>  ...
> +-- test partial write/pwrite via one byte transfer

4. Please

- Add the issue reference, like this:

	--
	-- gh-4651: ...
	--

- Start sentences from a capital letter, and finish with dot.

  parent reply	other threads:[~2020-06-09 22:55 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-21 21:39 Cyrill Gorcunov
2020-05-06 17:08 ` Alexander Turenko
2020-05-15  9:00   ` Cyrill Gorcunov
2020-06-09 16:55     ` Alexander Turenko
2020-06-09 22:55     ` Vladislav Shpilevoy
2020-06-09 22:55 ` Vladislav Shpilevoy [this message]
2020-06-10  7:52   ` Cyrill Gorcunov
2020-06-11 19:36     ` Vladislav Shpilevoy
2020-06-11 19:43       ` Cyrill Gorcunov
2020-06-11 19:56         ` Vladislav Shpilevoy
2020-06-11 20:12           ` Cyrill Gorcunov
2020-06-11 19:56 ` Vladislav Shpilevoy
  -- strict thread matches above, loose matches on Subject: below --
2019-11-26 18:05 [Tarantool-patches] [PATCH] fio/coio: Handle " Cyrill Gorcunov
2019-12-04  9:44 ` Cyrill Gorcunov

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