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Date: Tue, 26 Mar 2024 10:39:02 +0100
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Subject: Re: [PATCH v3 04/11] readahead: rework loop in
 page_cache_ra_unbounded()
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To: Matthew Wilcox <willy@infradead.org>,
 "Pankaj Raghav (Samsung)" <kernel@pankajraghav.com>
Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
 gost.dev@samsung.com, chandan.babu@oracle.com, mcgrof@kernel.org,
 djwong@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org,
 david@fromorbit.com, akpm@linux-foundation.org,
 Pankaj Raghav <p.raghav@samsung.com>
References: <20240313170253.2324812-1-kernel@pankajraghav.com>
 <20240313170253.2324812-5-kernel@pankajraghav.com>
 <ZgHFPZ9tNLLjKZpz@casper.infradead.org>
From: Hannes Reinecke <hare@suse.de>
In-Reply-To: <ZgHFPZ9tNLLjKZpz@casper.infradead.org>
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On 3/25/24 19:41, Matthew Wilcox wrote:
> On Wed, Mar 13, 2024 at 06:02:46PM +0100, Pankaj Raghav (Samsung) wrote:
>> @@ -239,8 +239,8 @@ void page_cache_ra_unbounded(struct readahead_control *ractl,
>>   			 * not worth getting one just for that.
>>   			 */
>>   			read_pages(ractl);
>> -			ractl->_index++;
>> -			i = ractl->_index + ractl->_nr_pages - index - 1;
>> +			ractl->_index += folio_nr_pages(folio);
>> +			i = ractl->_index + ractl->_nr_pages - index;
>>   			continue;
>>   		}
>>   
>> @@ -252,13 +252,14 @@ void page_cache_ra_unbounded(struct readahead_control *ractl,
>>   			folio_put(folio);
>>   			read_pages(ractl);
>>   			ractl->_index++;
>> -			i = ractl->_index + ractl->_nr_pages - index - 1;
>> +			i = ractl->_index + ractl->_nr_pages - index;
>>   			continue;
>>   		}
> 
> You changed index++ in the first hunk, but not the second hunk.  Is that
> intentional?

Hmm. Looks you are right; it should be modified, too.
Will be fixing it up.

Cheers,

Hannes