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From: Gabriel Krisman Bertazi <[email protected]>
To: Ammar Faizi <[email protected]>
Cc: Jens Axboe <[email protected]>,
	Pavel Begunkov <[email protected]>,
	Breno Leitao <[email protected]>,
	Christian Mazakas <[email protected]>,
	Gilang Fachrezy <[email protected]>,
	VNLX Kernel Department <[email protected]>,
	io-uring Mailing List <[email protected]>,
	Linux Kernel Mailing List <[email protected]>,
	GNU/Weeb Mailing List <[email protected]>
Subject: Re: [PATCH liburing v1 4/4] man/io_uring_prep_splice.3: Explain more about io_uring_prep_splice()
Date: Thu, 12 Jan 2023 14:26:00 -0300	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]> (Ammar Faizi's message of "Thu, 12 Jan 2023 22:57:09 +0700")

Ammar Faizi <[email protected]> writes:

> From: Ammar Faizi <[email protected]>
>
> I have found two people confused about the io_uring_prep_splice()
> function, especially on the offset part. The current manpage for
> io_uring_prep_splice() doesn't tell about the rules of the offset
> arguments.
>
> Despite these rules are already noted in "man 2 io_uring_enter",
> people who want to know about this prep function will prefer to read
> "man 3 io_uring_prep_splice".
>
> Let's explain it there!

Hi Ammar,

A few suggestions below:

> --- a/man/io_uring_prep_splice.3
> +++ b/man/io_uring_prep_splice.3
> @@ -52,6 +52,34 @@ and
>  .I fd_in
>  given as a registered file descriptor offset.
>
> +If
> +.I fd_in
> +refers to a pipe,
> +.IR off_in
> +must be -1.

Maybe

"off_in is ignored and must be set to -1."

> +
> +If
> +.I fd_in
> +does not refer to a pipe and
> +.I off_in
> +is -1, then bytes are read from

bytes -> nbytes ?

> +.I fd_in
> +starting from the file offset and it is adjusted appropriately.

What do you think:

starting from the file offset, which is incremented by the number of
bytes read.

> +If
> +.I fd_in
> +does not refer to a pipe and
> +.I off_in
> +is not -1, then the starting offset of
> +.I fd_in
> +will be
> +.IR off_in .
> +
> +The same rules apply to
> +.I fd_out
> +and
> +.IR off_out .
> +
>  This function prepares an async
>  .BR splice (2)
>  request. See that man page for details.
> @@ -78,3 +106,13 @@ field.
>  .BR io_uring_submit (3),
>  .BR io_uring_register (2),
>  .BR splice (2)
> +
> +.SH NOTES
> +Note that even if
> +.I fd_in
> +or
> +.I fd_out
> +refers to a pipe, the splice operation can still failed with

failed -> fail

Thanks,

-- 
Gabriel Krisman Bertazi

  reply	other threads:[~2023-01-12 18:03 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-12 15:57 [PATCH liburing v1 0/4] liburing updates for 2.4 Ammar Faizi
2023-01-12 15:57 ` [PATCH liburing v1 1/4] liburing-ffi.map: Add io_uring_prep_msg_ring_cqe_flags() function Ammar Faizi
2023-01-12 15:57 ` [PATCH liburing v1 2/4] CHANGELOG: Note about --nolibc configure option deprecation Ammar Faizi
2023-01-12 15:57 ` [PATCH liburing v1 3/4] liburing.h: 's/is adjust/is adjusted/' and fix indentation Ammar Faizi
2023-01-12 15:57 ` [PATCH liburing v1 4/4] man/io_uring_prep_splice.3: Explain more about io_uring_prep_splice() Ammar Faizi
2023-01-12 17:26   ` Gabriel Krisman Bertazi [this message]
2023-01-12 17:49     ` Jens Axboe
2023-01-12 17:49 ` [PATCH liburing v1 0/4] liburing updates for 2.4 Jens Axboe

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