lkml.org 
[lkml]   [2015]   [May]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2] splice: sendfile() at once fails for big files
On 05/06/2015 08:38 AM, leroy christophe wrote:
>
> Le 06/05/2015 16:23, Jens Axboe a écrit :
>> On 05/05/2015 09:41 PM, Linus Torvalds wrote:
>>> Jens, ping?
>>>
>>> The test results should make this a no-brainer, but I hate how random
>>> these flag ops.
>>
>> Missed the original, apparently. I too am confused how this is a
>> correctness fix and not just an optimization.
>>
>> + if (read_len < len)
>> + sd->flags |= SPLICE_F_MORE;
>> + else if (!more)
>> + sd->flags &= ~SPLICE_F_MORE;
>>
>> Should that check be for 'more', not '!more'?
>>
>>
> @@ -1204,6 +1204,7 @@ ssize_t splice_direct_to_actor(struct file *in,
> struct splice_desc *sd,
> * Don't block on output, we have to drain the direct pipe.
> */
> sd->flags &= ~SPLICE_F_NONBLOCK;
> + more = sd->flags & SPLICE_F_MORE;
>
> while (len) {
> size_t read_len;
> @@ -1216,6 +1217,10 @@ ssize_t splice_direct_to_actor(struct file *in,
> struct splice_desc *sd,
> read_len = ret;
> sd->total_len = read_len;
>
> + if (read_len < len)
> + sd->flags |= SPLICE_F_MORE;
> + else if (!more)
> + sd->flags &= ~SPLICE_F_MORE;
>
>
>
> 'more' contains whether sendfile() has been called with SPLICE_F_MORE or
> not.
> Until all bytes are processed, we have to force SPLICE_F_MORE regardless
> of how sendfile() was called.
> Once all bytes have been read, we have to reset the flags according to
> how sendfile() was called, so if 'more' is NOT set, we have to clear
> SPLICE_F_MORE from sd->flags (which was unconditionaly set for
> processing the first bytes)

Ah gotcha, that looks correct. Patch is fine with me then.

--
Jens Axboe



\
 
 \ /
  Last update: 2015-05-06 17:21    [W:0.054 / U:0.152 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site