linux-kernel - Re: On current git head webservers stopped working

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Message-ID: <46974ABF.9030408@googlemail.com>
Date:	Fri, 13 Jul 2007 11:49:51 +0200
From:	Gabriel C <nix.or.die@...glemail.com>
To:	Jens Axboe <jens.axboe@...cle.com>
CC:	linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: On current git head webservers stopped working

Jens Axboe wrote:
> On Fri, Jul 13 2007, Gabriel C wrote:
>   
>> Hello ,
>>
>> While doing some tests with 2.6.22-git2 ( at the time head
>> 4eb6bf6bfb580afaf1e1a1d30cba17a078530cf4 ) all my webservers stopped
>> working.
>> I can't get any file using wget or whatever else , everything hangs
>> after 1% forever.
>>
>> I bisected this and here the result:
>>
>> 534f2aaa6ab07cd71164180bc958a7dcde41db11 is first bad commit
>> commit 534f2aaa6ab07cd71164180bc958a7dcde41db11
>> Author: Jens Axboe <jens.axboe@...cle.com>
>> Date:   Fri Jun 1 14:52:37 2007 +0200
>>
>>     sys_sendfile: switch to using ->splice_read, if available
>>
>>     This patch makes sendfile prefer to use ->splice_read(), if it's
>>     available in the file_operations structure.
>>
>>     Signed-off-by: Jens Axboe <jens.axboe@...cle.com>
>>
>> :040000 040000 b19013793692eee0f632b3703dca0bd40cea753f
>> ed50576c0d3f0d3ce9f1a2ac9336d1164b45f63f M      fs
>>     
>
> Does this work?
>   

Yes , it does. Thx :)

> diff --git a/fs/splice.c b/fs/splice.c
> index ed2ce99..92646aa 100644
> --- a/fs/splice.c
> +++ b/fs/splice.c
> @@ -491,7 +491,7 @@ ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
>  
>  	ret = 0;
>  	spliced = 0;
> -	while (len) {
> +	while (len && !spliced) {
>  		ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
>  
>  		if (ret < 0)
> @@ -1051,15 +1051,10 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
>  	sd->flags &= ~SPLICE_F_NONBLOCK;
>  
>  	while (len) {
> -		size_t read_len, max_read_len;
> -
> -		/*
> -		 * Do at most PIPE_BUFFERS pages worth of transfer:
> -		 */
> -		max_read_len = min(len, (size_t)(PIPE_BUFFERS*PAGE_SIZE));
> +		size_t read_len;
>  
> -		ret = do_splice_to(in, &sd->pos, pipe, max_read_len, flags);
> -		if (unlikely(ret < 0))
> +		ret = do_splice_to(in, &sd->pos, pipe, len, flags);
> +		if (unlikely(ret <= 0))
>  			goto out_release;
>  
>  		read_len = ret;
> @@ -1071,26 +1066,17 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
>  		 * could get stuck data in the internal pipe:
>  		 */
>  		ret = actor(pipe, sd);
> -		if (unlikely(ret < 0))
> +		if (unlikely(ret <= 0))
>  			goto out_release;
>  
>  		bytes += ret;
>  		len -= ret;
>  
> -		/*
> -		 * In nonblocking mode, if we got back a short read then
> -		 * that was due to either an IO error or due to the
> -		 * pagecache entry not being there. In the IO error case
> -		 * the _next_ splice attempt will produce a clean IO error
> -		 * return value (not a short read), so in both cases it's
> -		 * correct to break out of the loop here:
> -		 */
> -		if ((flags & SPLICE_F_NONBLOCK) && (read_len < max_read_len))
> -			break;
> +		if (ret < read_len)
> +			goto out_release;
>  	}
>  
>  	pipe->nrbufs = pipe->curbuf = 0;
> -
>  	return bytes;
>  
>  out_release:
> @@ -1152,10 +1138,12 @@ long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
>  		.pos		= *ppos,
>  		.u.file		= out,
>  	};
> -	size_t ret;
> +	long ret;
>  
>  	ret = splice_direct_to_actor(in, &sd, direct_splice_actor);
> -	*ppos = sd.pos;
> +	if (ret > 0)
> +		*ppos += ret;
> +
>  	return ret;
>  }
>  
>
>   

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