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From: Jens Axboe <axboe@kernel.dk>
To: Matthew Wilcox <willy@infradead.org>
Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
	hch@infradead.org, akpm@linux-foundation.org
Subject: Re: [PATCH 1/3] mm: provide filemap_range_needs_writeback() helper
Date: Mon, 8 Feb 2021 16:21:50 -0700	[thread overview]
Message-ID: <b4fc9f1e-e1b6-ff46-e5cf-5e59ca9db936@kernel.dk> (raw)
In-Reply-To: <20210208230205.GV308988@casper.infradead.org>

On 2/8/21 4:02 PM, Matthew Wilcox wrote:
> On Mon, Feb 08, 2021 at 03:18:27PM -0700, Jens Axboe wrote:
>> +	rcu_read_lock();
>> +	xas_for_each(&xas, head, max) {
>> +		if (xas_retry(&xas, head))
>> +			continue;
>> +		if (xa_is_value(head))
>> +			continue;
>> +		page = find_subpage(head, xas.xa_index);
>> +		if (PageDirty(page) || PageLocked(page) || PageWriteback(page))
>> +			break;
>> +		page = NULL;
>> +	}
>> +	rcu_read_unlock();
> 
> There's no need to find the sub-page for any of these three conditions --
> the bit will be set on the head page.

Gotcha, that makes it simpler. I'll make the edit.

-- 
Jens Axboe


  reply	other threads:[~2021-02-08 23:22 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-08 22:18 [PATCHSET 0/3] Improve IOCB_NOWAIT O_DIRECT Jens Axboe
2021-02-08 22:18 ` [PATCH 1/3] mm: provide filemap_range_needs_writeback() helper Jens Axboe
2021-02-08 23:02   ` Matthew Wilcox
2021-02-08 23:21     ` Jens Axboe [this message]
2021-02-08 22:18 ` [PATCH 2/3] mm: use filemap_range_needs_writeback() for O_DIRECT IO Jens Axboe
2021-02-08 22:18 ` [PATCH 3/3] iomap: " Jens Axboe
2021-02-08 23:28 ` [PATCHSET 0/3] Improve IOCB_NOWAIT O_DIRECT Dave Chinner
2021-02-08 23:37   ` Jens Axboe
2021-02-09  0:14     ` Dave Chinner
2021-02-09  2:15       ` Jens Axboe
2021-02-09  2:30 [PATCHSET v2 0/3] Improve IOCB_NOWAIT O_DIRECT reads Jens Axboe
2021-02-09  2:30 ` [PATCH 1/3] mm: provide filemap_range_needs_writeback() helper Jens Axboe
2021-02-09  7:47   ` Christoph Hellwig
2021-02-09 14:30     ` Jens Axboe
2021-02-24 16:44 [PATCHSET v3 0/3] Improve IOCB_NOWAIT O_DIRECT reads Jens Axboe
2021-02-24 16:44 ` [PATCH 1/3] mm: provide filemap_range_needs_writeback() helper Jens Axboe
2021-02-24 16:50   ` Matthew Wilcox
2021-02-24 16:53     ` Jens Axboe
2021-02-24 17:22   ` Jan Kara

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