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* [PATCH] io_uring: no read-retry on -EAGAIN error and O_NONBLOCK marked file
@ 2020-09-02 16:00 Jens Axboe
  2020-09-02 16:09 ` Pavel Begunkov
  0 siblings, 1 reply; 3+ messages in thread
From: Jens Axboe @ 2020-09-02 16:00 UTC (permalink / raw)
  To: io-uring; +Cc: Norman Maurer

    Actually two things that need fixing up here:
    
    - The io_rw_reissue() -EAGAIN retry is explicit to block devices and
      regular files, so don't ever attempt to do that on other types of
      files.
    
    - If we hit -EAGAIN on a nonblock marked file, don't arm poll handler for
      it. It should just complete with -EAGAIN.
    
    Cc: stable@vger.kernel.org
    Reported-by: Norman Maurer <norman.maurer@googlemail.com>
    Signed-off-by: Jens Axboe <axboe@kernel.dk>

---

diff --git a/fs/io_uring.c b/fs/io_uring.c
index b1ccd7072d93..65656102bbeb 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2300,8 +2300,11 @@ static bool io_resubmit_prep(struct io_kiocb *req, int error)
 static bool io_rw_reissue(struct io_kiocb *req, long res)
 {
 #ifdef CONFIG_BLOCK
+	umode_t mode = file_inode(req->file)->i_mode;
 	int ret;
 
+	if (!S_ISBLK(mode) && !S_ISREG(mode))
+		return false;
 	if ((res != -EAGAIN && res != -EOPNOTSUPP) || io_wq_current_is_worker())
 		return false;
 
@@ -3146,6 +3149,9 @@ static int io_read(struct io_kiocb *req, bool force_nonblock,
 		/* IOPOLL retry should happen for io-wq threads */
 		if (!force_nonblock && !(req->ctx->flags & IORING_SETUP_IOPOLL))
 			goto done;
+		/* no retry on NONBLOCK marked file */
+		if (req->file->f_flags & O_NONBLOCK)
+			goto done;
 		/* some cases will consume bytes even on error returns */
 		iov_iter_revert(iter, iov_count - iov_iter_count(iter));
 		ret = io_setup_async_rw(req, iovec, inline_vecs, iter, false);
@@ -3291,8 +3297,12 @@ static int io_write(struct io_kiocb *req, bool force_nonblock,
 		/* IOPOLL retry should happen for io-wq threads */
 		if ((req->ctx->flags & IORING_SETUP_IOPOLL) && ret2 == -EAGAIN)
 			goto copy_iov;
+done:
 		kiocb_done(kiocb, ret2, cs);
 	} else {
+		/* no retry on NONBLOCK marked file */
+		if (req->file->f_flags & O_NONBLOCK)
+			goto done;
 copy_iov:
 		/* some cases will consume bytes even on error returns */
 		iov_iter_revert(iter, iov_count - iov_iter_count(iter));

-- 
Jens Axboe


^ permalink raw reply related	[flat|nested] 3+ messages in thread
* Re: [PATCH] io_uring: no read-retry on -EAGAIN error and O_NONBLOCK marked file
  2020-09-02 16:00 [PATCH] io_uring: no read-retry on -EAGAIN error and O_NONBLOCK marked file Jens Axboe
@ 2020-09-02 16:09 ` Pavel Begunkov
  2020-09-02 16:32   ` Jens Axboe
  0 siblings, 1 reply; 3+ messages in thread
From: Pavel Begunkov @ 2020-09-02 16:09 UTC (permalink / raw)
  To: Jens Axboe, io-uring; +Cc: Norman Maurer

On 02/09/2020 19:00, Jens Axboe wrote:
>     Actually two things that need fixing up here:
>     
>     - The io_rw_reissue() -EAGAIN retry is explicit to block devices and
>       regular files, so don't ever attempt to do that on other types of
>       files.
>     
>     - If we hit -EAGAIN on a nonblock marked file, don't arm poll handler for
>       it. It should just complete with -EAGAIN.
>     
>     Cc: stable@vger.kernel.org
>     Reported-by: Norman Maurer <norman.maurer@googlemail.com>
>     Signed-off-by: Jens Axboe <axboe@kernel.dk>
> 
> ---
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index b1ccd7072d93..65656102bbeb 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -2300,8 +2300,11 @@ static bool io_resubmit_prep(struct io_kiocb *req, int error)
>  static bool io_rw_reissue(struct io_kiocb *req, long res)
>  {
>  #ifdef CONFIG_BLOCK
> +	umode_t mode = file_inode(req->file)->i_mode;
>  	int ret;
>  
> +	if (!S_ISBLK(mode) && !S_ISREG(mode))
> +		return false;
>  	if ((res != -EAGAIN && res != -EOPNOTSUPP) || io_wq_current_is_worker())
>  		return false;
>  
> @@ -3146,6 +3149,9 @@ static int io_read(struct io_kiocb *req, bool force_nonblock,
>  		/* IOPOLL retry should happen for io-wq threads */
>  		if (!force_nonblock && !(req->ctx->flags & IORING_SETUP_IOPOLL))
>  			goto done;
> +		/* no retry on NONBLOCK marked file */
> +		if (req->file->f_flags & O_NONBLOCK)
> +			goto done;

Looks like it works with open(O_NONBLOCK) but not with IOCB_NOWAIT in the
request's flags. Is that so?


>  		/* some cases will consume bytes even on error returns */
>  		iov_iter_revert(iter, iov_count - iov_iter_count(iter));
>  		ret = io_setup_async_rw(req, iovec, inline_vecs, iter, false);
> @@ -3291,8 +3297,12 @@ static int io_write(struct io_kiocb *req, bool force_nonblock,
>  		/* IOPOLL retry should happen for io-wq threads */
>  		if ((req->ctx->flags & IORING_SETUP_IOPOLL) && ret2 == -EAGAIN)
>  			goto copy_iov;
> +done:
>  		kiocb_done(kiocb, ret2, cs);
>  	} else {
> +		/* no retry on NONBLOCK marked file */
> +		if (req->file->f_flags & O_NONBLOCK)
> +			goto done;
>  copy_iov:
>  		/* some cases will consume bytes even on error returns */
>  		iov_iter_revert(iter, iov_count - iov_iter_count(iter));
> 

-- 
Pavel Begunkov

^ permalink raw reply	[flat|nested] 3+ messages in thread
* Re: [PATCH] io_uring: no read-retry on -EAGAIN error and O_NONBLOCK marked file
  2020-09-02 16:09 ` Pavel Begunkov
@ 2020-09-02 16:32   ` Jens Axboe
  0 siblings, 0 replies; 3+ messages in thread
From: Jens Axboe @ 2020-09-02 16:32 UTC (permalink / raw)
  To: Pavel Begunkov, io-uring; +Cc: Norman Maurer

On 9/2/20 10:09 AM, Pavel Begunkov wrote:
> On 02/09/2020 19:00, Jens Axboe wrote:
>>     Actually two things that need fixing up here:
>>     
>>     - The io_rw_reissue() -EAGAIN retry is explicit to block devices and
>>       regular files, so don't ever attempt to do that on other types of
>>       files.
>>     
>>     - If we hit -EAGAIN on a nonblock marked file, don't arm poll handler for
>>       it. It should just complete with -EAGAIN.
>>     
>>     Cc: stable@vger.kernel.org
>>     Reported-by: Norman Maurer <norman.maurer@googlemail.com>
>>     Signed-off-by: Jens Axboe <axboe@kernel.dk>
>>
>> ---
>>
>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>> index b1ccd7072d93..65656102bbeb 100644
>> --- a/fs/io_uring.c
>> +++ b/fs/io_uring.c
>> @@ -2300,8 +2300,11 @@ static bool io_resubmit_prep(struct io_kiocb *req, int error)
>>  static bool io_rw_reissue(struct io_kiocb *req, long res)
>>  {
>>  #ifdef CONFIG_BLOCK
>> +	umode_t mode = file_inode(req->file)->i_mode;
>>  	int ret;
>>  
>> +	if (!S_ISBLK(mode) && !S_ISREG(mode))
>> +		return false;
>>  	if ((res != -EAGAIN && res != -EOPNOTSUPP) || io_wq_current_is_worker())
>>  		return false;
>>  
>> @@ -3146,6 +3149,9 @@ static int io_read(struct io_kiocb *req, bool force_nonblock,
>>  		/* IOPOLL retry should happen for io-wq threads */
>>  		if (!force_nonblock && !(req->ctx->flags & IORING_SETUP_IOPOLL))
>>  			goto done;
>> +		/* no retry on NONBLOCK marked file */
>> +		if (req->file->f_flags & O_NONBLOCK)
>> +			goto done;
> 
> Looks like it works with open(O_NONBLOCK) but not with IOCB_NOWAIT in the
> request's flags. Is that so?

The IOCB_NOWAIT case should already be fine, it's just the O_NONBLOCK that
isn't covered. IOCB_NOWAIT on a socket unhelpfully fails anyway, since
FMODE_NOWAIT isn't available. Arguably something that should be fixed
separately.

-- 
Jens Axboe


^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-09-02 16:32 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2020-09-02 16:00 [PATCH] io_uring: no read-retry on -EAGAIN error and O_NONBLOCK marked file Jens Axboe
2020-09-02 16:09 ` Pavel Begunkov
2020-09-02 16:32   ` Jens Axboe

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