diff mbox series

[4/9,next] fs/io_uring Don't use the return value from import_iovec().

Message ID 0dc67994b6b2478caa3d96a9e24d2bfb@AcuMS.aculab.com
State New
Headers show
Series Changes to code that reads iovec from userspace | expand

Commit Message

David Laight Sept. 15, 2020, 2:55 p.m. UTC
This is the only code that relies on import_iovec() returning
iter.count on success.
This allows a better interface to import_iovec().

Signed-off-by: David Laight <david.laight@aculab.com>
---
 fs/io_uring.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Comments

Christoph Hellwig Sept. 21, 2020, 2:14 p.m. UTC | #1
On Tue, Sep 15, 2020 at 02:55:20PM +0000, David Laight wrote:
> 
> This is the only code that relies on import_iovec() returning
> iter.count on success.
> This allows a better interface to import_iovec().

This looks generall sane, but a comment below:

> @@ -3123,7 +3123,7 @@ static int io_read(struct io_kiocb *req, bool force_nonblock,
>  	if (ret < 0)
>  		return ret;
>  	iov_count = iov_iter_count(iter);
> -	io_size = ret;
> +	io_size = iov_count;
>  	req->result = io_size;
>  	ret = 0;
>  
> @@ -3246,7 +3246,7 @@ static int io_write(struct io_kiocb *req, bool force_nonblock,
>  	if (ret < 0)
>  		return ret;
>  	iov_count = iov_iter_count(iter);
> -	io_size = ret;
> +	io_size = iov_count;
>  	req->result = io_size;

I tink the local iov_count variable can go away in both functions,
as io_size only changes after the last use of iov_count (io_read) or
not at all (io_write).
David Laight Sept. 21, 2020, 2:38 p.m. UTC | #2
From: Christoph Hellwig
> Sent: 21 September 2020 15:15
> 
> On Tue, Sep 15, 2020 at 02:55:20PM +0000, David Laight wrote:
> >
> > This is the only code that relies on import_iovec() returning
> > iter.count on success.
> > This allows a better interface to import_iovec().
> 
> This looks generall sane, but a comment below:
> 
> > @@ -3123,7 +3123,7 @@ static int io_read(struct io_kiocb *req, bool force_nonblock,
> >  	if (ret < 0)
> >  		return ret;
> >  	iov_count = iov_iter_count(iter);
> > -	io_size = ret;
> > +	io_size = iov_count;
> >  	req->result = io_size;
> >  	ret = 0;
> >
> > @@ -3246,7 +3246,7 @@ static int io_write(struct io_kiocb *req, bool force_nonblock,
> >  	if (ret < 0)
> >  		return ret;
> >  	iov_count = iov_iter_count(iter);
> > -	io_size = ret;
> > +	io_size = iov_count;
> >  	req->result = io_size;
> 
> I tink the local iov_count variable can go away in both functions,
> as io_size only changes after the last use of iov_count (io_read) or
> not at all (io_write).

Yes, the compiler will probably make that optimisation.
I did a minimal change because my head hurts whenever I look at io_uring.c.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
Pavel Begunkov Sept. 21, 2020, 4:01 p.m. UTC | #3
On 21/09/2020 17:38, David Laight wrote:
> From: Christoph Hellwig
>> Sent: 21 September 2020 15:15
>>
>> On Tue, Sep 15, 2020 at 02:55:20PM +0000, David Laight wrote:
>>>
>>> This is the only code that relies on import_iovec() returning
>>> iter.count on success.
>>> This allows a better interface to import_iovec().

Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>

>>
>> This looks generall sane, but a comment below:
>>
>>> @@ -3123,7 +3123,7 @@ static int io_read(struct io_kiocb *req, bool force_nonblock,
>>>  	if (ret < 0)
>>>  		return ret;
>>>  	iov_count = iov_iter_count(iter);
>>> -	io_size = ret;
>>> +	io_size = iov_count;
>>>  	req->result = io_size;
>>>  	ret = 0;
>>>
>>> @@ -3246,7 +3246,7 @@ static int io_write(struct io_kiocb *req, bool force_nonblock,
>>>  	if (ret < 0)
>>>  		return ret;
>>>  	iov_count = iov_iter_count(iter);
>>> -	io_size = ret;
>>> +	io_size = iov_count;
>>>  	req->result = io_size;
>>
>> I tink the local iov_count variable can go away in both functions,
>> as io_size only changes after the last use of iov_count (io_read) or
>> not at all (io_write).

Yes, iov_count should be killed, now or later.

> 
> Yes, the compiler will probably make that optimisation.
> I did a minimal change because my head hurts whenever I look at io_uring.c.
> 
> 	David
> 
> -
> Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
> Registration No: 1397386 (Wales)
>
Pavel Begunkov Nov. 7, 2020, 1:14 a.m. UTC | #4
On 15/09/2020 15:55, David Laight wrote:
> 
> This is the only code that relies on import_iovec() returning
> iter.count on success.
> This allows a better interface to import_iovec().

Seems this got nowhere. I'll pick it and send with some other
patches to Jens.

> Signed-off-by: David Laight <david.laight@aculab.com>
> ---
>  fs/io_uring.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 3790c7fe9fee..0df43882e4b3 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -2824,7 +2824,7 @@ static ssize_t __io_import_iovec(int rw, struct io_kiocb *req,
>  
>  		ret = import_single_range(rw, buf, sqe_len, *iovec, iter);
>  		*iovec = NULL;
> -		return ret < 0 ? ret : sqe_len;
> +		return ret;
>  	}
>  
>  	if (req->flags & REQ_F_BUFFER_SELECT) {
> @@ -2853,7 +2853,7 @@ static ssize_t io_import_iovec(int rw, struct io_kiocb *req,
>  	if (!req->io)
>  		return __io_import_iovec(rw, req, iovec, iter, needs_lock);
>  	*iovec = NULL;
> -	return iov_iter_count(&req->io->rw.iter);
> +	return 0;
>  }
>  
>  static inline loff_t *io_kiocb_ppos(struct kiocb *kiocb)
> @@ -3123,7 +3123,7 @@ static int io_read(struct io_kiocb *req, bool force_nonblock,
>  	if (ret < 0)
>  		return ret;
>  	iov_count = iov_iter_count(iter);
> -	io_size = ret;
> +	io_size = iov_count;
>  	req->result = io_size;
>  	ret = 0;
>  
> @@ -3246,7 +3246,7 @@ static int io_write(struct io_kiocb *req, bool force_nonblock,
>  	if (ret < 0)
>  		return ret;
>  	iov_count = iov_iter_count(iter);
> -	io_size = ret;
> +	io_size = iov_count;
>  	req->result = io_size;
>  
>  	/* Ensure we clear previously set non-block flag */
>
diff mbox series

Patch

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 3790c7fe9fee..0df43882e4b3 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2824,7 +2824,7 @@  static ssize_t __io_import_iovec(int rw, struct io_kiocb *req,
 
 		ret = import_single_range(rw, buf, sqe_len, *iovec, iter);
 		*iovec = NULL;
-		return ret < 0 ? ret : sqe_len;
+		return ret;
 	}
 
 	if (req->flags & REQ_F_BUFFER_SELECT) {
@@ -2853,7 +2853,7 @@  static ssize_t io_import_iovec(int rw, struct io_kiocb *req,
 	if (!req->io)
 		return __io_import_iovec(rw, req, iovec, iter, needs_lock);
 	*iovec = NULL;
-	return iov_iter_count(&req->io->rw.iter);
+	return 0;
 }
 
 static inline loff_t *io_kiocb_ppos(struct kiocb *kiocb)
@@ -3123,7 +3123,7 @@  static int io_read(struct io_kiocb *req, bool force_nonblock,
 	if (ret < 0)
 		return ret;
 	iov_count = iov_iter_count(iter);
-	io_size = ret;
+	io_size = iov_count;
 	req->result = io_size;
 	ret = 0;
 
@@ -3246,7 +3246,7 @@  static int io_write(struct io_kiocb *req, bool force_nonblock,
 	if (ret < 0)
 		return ret;
 	iov_count = iov_iter_count(iter);
-	io_size = ret;
+	io_size = iov_count;
 	req->result = io_size;
 
 	/* Ensure we clear previously set non-block flag */