As 'head' is not updated after head+1 is assigned to pipe->head, the
condition being tested here is exactly the same as in the big if
statement just above. Merge the two bodies.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 fs/pipe.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/fs/pipe.c b/fs/pipe.c
index 097400cce241..27385e3e5417 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -547,10 +547,8 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from)
 
 			if (!iov_iter_count(from))
 				break;
-		}
-
-		if (!pipe_full(head, pipe->tail, pipe->max_usage))
 			continue;
+		}
 
 		/* Wait for buffer space to become available. */
 		if ((filp->f_flags & O_NONBLOCK) ||
-- 
2.48.1

On 03/07, Rasmus Villemoes wrote:
>
> As 'head' is not updated after head+1 is assigned to pipe->head, the
> condition being tested here is exactly the same as in the big if
> statement just above. Merge the two bodies.

Yes.

But Mateusz has already sent the same patch, please see

	[PATCH 1/3] pipe: drop an always true check in anon_pipe_write()
	https://lore.kernel.org/all/20250303230409.452687-2-mjguzik@gmail.com/

Oleg.

> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> ---
>  fs/pipe.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/fs/pipe.c b/fs/pipe.c
> index 097400cce241..27385e3e5417 100644
> --- a/fs/pipe.c
> +++ b/fs/pipe.c
> @@ -547,10 +547,8 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from)
>
>  			if (!iov_iter_count(from))
>  				break;
> -		}
> -
> -		if (!pipe_full(head, pipe->tail, pipe->max_usage))
>  			continue;
> +		}
>
>  		/* Wait for buffer space to become available. */
>  		if ((filp->f_flags & O_NONBLOCK) ||
> --
> 2.48.1
>

On Fri, Mar 07, 2025 at 11:25:00PM +0100, Rasmus Villemoes wrote:
> As 'head' is not updated after head+1 is assigned to pipe->head, the
> condition being tested here is exactly the same as in the big if
> statement just above. Merge the two bodies.
> 
> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> ---
>  fs/pipe.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/fs/pipe.c b/fs/pipe.c
> index 097400cce241..27385e3e5417 100644
> --- a/fs/pipe.c
> +++ b/fs/pipe.c
> @@ -547,10 +547,8 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from)
>  
>  			if (!iov_iter_count(from))
>  				break;
> -		}
> -
> -		if (!pipe_full(head, pipe->tail, pipe->max_usage))
>  			continue;
> +		}
>  
>  		/* Wait for buffer space to become available. */
>  		if ((filp->f_flags & O_NONBLOCK) ||

I already posted this :)

It is hanging out in the vfs trees (and -next), see
https://lore.kernel.org/linux-fsdevel/20250303230409.452687-2-mjguzik@gmail.com/

On Fri, Mar 07 2025, Mateusz Guzik <mjguzik@gmail.com> wrote:

> On Fri, Mar 07, 2025 at 11:25:00PM +0100, Rasmus Villemoes wrote:
>> As 'head' is not updated after head+1 is assigned to pipe->head, the
>> condition being tested here is exactly the same as in the big if
>> statement just above. Merge the two bodies.
>> 
>> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
>> ---
>>  fs/pipe.c | 4 +---
>>  1 file changed, 1 insertion(+), 3 deletions(-)
>> 
>> diff --git a/fs/pipe.c b/fs/pipe.c
>> index 097400cce241..27385e3e5417 100644
>> --- a/fs/pipe.c
>> +++ b/fs/pipe.c
>> @@ -547,10 +547,8 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from)
>>  
>>  			if (!iov_iter_count(from))
>>  				break;
>> -		}
>> -
>> -		if (!pipe_full(head, pipe->tail, pipe->max_usage))
>>  			continue;
>> +		}
>>  
>>  		/* Wait for buffer space to become available. */
>>  		if ((filp->f_flags & O_NONBLOCK) ||
>
> I already posted this :)
>

Ah, never mind then, also for that other patch I just sent. Just
stumbled on those while trying to proof-read the pipe code.

Rasmus