public inbox for [email protected]
 help / color / mirror / Atom feed
From: Jens Axboe <[email protected]>
To: Nadav Amit <[email protected]>, [email protected]
Cc: Nadav Amit <[email protected]>,
	Andrea Arcangeli <[email protected]>,
	Peter Xu <[email protected]>,
	Alexander Viro <[email protected]>,
	[email protected], [email protected],
	[email protected]
Subject: Re: [RFC PATCH 07/13] fs/userfaultfd: support read_iter to use io_uring
Date: Mon, 30 Nov 2020 11:20:27 -0700	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

On 11/28/20 5:45 PM, Nadav Amit wrote:
> From: Nadav Amit <[email protected]>
> 
> iouring with userfaultfd cannot currently be used fixed buffers since
> userfaultfd does not provide read_iter(). This is required to allow
> asynchronous (queued) reads from userfaultfd.
> 
> To support async-reads of userfaultfd provide read_iter() instead of
> read().
> 
> Cc: Jens Axboe <[email protected]>
> Cc: Andrea Arcangeli <[email protected]>
> Cc: Peter Xu <[email protected]>
> Cc: Alexander Viro <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> Signed-off-by: Nadav Amit <[email protected]>
> ---
>  fs/userfaultfd.c | 18 ++++++++++--------
>  1 file changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
> index b6a04e526025..6333b4632742 100644
> --- a/fs/userfaultfd.c
> +++ b/fs/userfaultfd.c
> @@ -1195,9 +1195,9 @@ static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait,
>  	return ret;
>  }
>  
> -static ssize_t userfaultfd_read(struct file *file, char __user *buf,
> -				size_t count, loff_t *ppos)
> +static ssize_t userfaultfd_read_iter(struct kiocb *iocb, struct iov_iter *to)
>  {
> +	struct file *file = iocb->ki_filp;
>  	struct userfaultfd_ctx *ctx = file->private_data;
>  	ssize_t _ret, ret = 0;
>  	struct uffd_msg msg;
> @@ -1207,16 +1207,18 @@ static ssize_t userfaultfd_read(struct file *file, char __user *buf,
>  		return -EINVAL;
>  
>  	for (;;) {
> -		if (count < sizeof(msg))
> +		if (iov_iter_count(to) < sizeof(msg))
>  			return ret ? ret : -EINVAL;
>  		_ret = userfaultfd_ctx_read(ctx, no_wait, &msg);

'no_wait' should be changed to factor in iocb->ki_flags & IOCB_NOWAIT as well,
not just f_flags & O_NONBLOCK.

I didn't check your write_iter, but if appropriate, that should do that
too.

-- 
Jens Axboe


  reply	other threads:[~2020-11-30 18:21 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-29  0:45 [RFC PATCH 00/13] fs/userfaultfd: support iouring and polling Nadav Amit
2020-11-29  0:45 ` [RFC PATCH 01/13] fs/userfaultfd: fix wrong error code on WP & !VM_MAYWRITE Nadav Amit
2020-12-01 21:22   ` Mike Kravetz
2020-12-21 19:01     ` Peter Xu
2020-11-29  0:45 ` [RFC PATCH 02/13] fs/userfaultfd: fix wrong file usage with iouring Nadav Amit
2020-11-29  0:45 ` [RFC PATCH 03/13] selftests/vm/userfaultfd: wake after copy failure Nadav Amit
2020-12-21 19:28   ` Peter Xu
2020-12-21 19:51     ` Nadav Amit
2020-12-21 20:52       ` Peter Xu
2020-12-21 20:54         ` Nadav Amit
2020-11-29  0:45 ` [RFC PATCH 04/13] fs/userfaultfd: simplify locks in userfaultfd_ctx_read Nadav Amit
2020-11-29  0:45 ` [RFC PATCH 05/13] fs/userfaultfd: introduce UFFD_FEATURE_POLL Nadav Amit
2020-11-29  0:45 ` [RFC PATCH 06/13] iov_iter: support atomic copy_page_from_iter_iovec() Nadav Amit
2020-11-29  0:45 ` [RFC PATCH 07/13] fs/userfaultfd: support read_iter to use io_uring Nadav Amit
2020-11-30 18:20   ` Jens Axboe [this message]
2020-11-30 19:23     ` Nadav Amit
2020-11-29  0:45 ` [RFC PATCH 08/13] fs/userfaultfd: complete reads asynchronously Nadav Amit
2020-11-29  0:45 ` [RFC PATCH 09/13] fs/userfaultfd: use iov_iter for copy/zero Nadav Amit
2020-11-29  0:45 ` [RFC PATCH 10/13] fs/userfaultfd: add write_iter() interface Nadav Amit
2020-11-29  0:45 ` [RFC PATCH 11/13] fs/userfaultfd: complete write asynchronously Nadav Amit
2020-12-02  7:12   ` Nadav Amit
2020-11-29  0:45 ` [RFC PATCH 12/13] fs/userfaultfd: kmem-cache for wait-queue objects Nadav Amit
2020-11-30 19:51   ` Nadav Amit
2020-11-29  0:45 ` [RFC PATCH 13/13] selftests/vm/userfaultfd: iouring and polling tests Nadav Amit

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] \
    /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