From: Matthew Wilcox <willy@infradead.org>
To: antlists <antlists@youngman.org.uk>
Cc: Zhen Lei <thunder.leizhen@huawei.com>,
Minchan Kim <minchan@kernel.org>, Nitin Gupta <ngupta@vflare.org>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Jens Axboe <axboe@kernel.dk>,
linux-block <linux-block@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm <linux-mm@kvack.org>, Alasdair Kergon <agk@redhat.com>,
Mike Snitzer <snitzer@redhat.com>, dm-devel <dm-devel@redhat.com>,
Song Liu <song@kernel.org>,
linux-raid <linux-raid@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/4] eliminate SECTOR related magic numbers and duplicated conversions
Date: Tue, 5 May 2020 11:01:13 -0700 [thread overview]
Message-ID: <20200505180113.GJ16070@bombadil.infradead.org> (raw)
In-Reply-To: <ea522f15-991d-6f67-ba8b-9cb4954a1064@youngman.org.uk>
On Tue, May 05, 2020 at 06:32:36PM +0100, antlists wrote:
> On 05/05/2020 12:55, Zhen Lei wrote:
> > When I studied the code of mm/swap, I found "1 << (PAGE_SHIFT - 9)" appears
> > many times. So I try to clean up it.
> >
> > 1. Replace "1 << (PAGE_SHIFT - 9)" or similar with SECTORS_PER_PAGE
> > 2. Replace "PAGE_SHIFT - 9" with SECTORS_PER_PAGE_SHIFT
> > 3. Replace "9" with SECTOR_SHIFT
> > 4. Replace "512" with SECTOR_SIZE
>
> Naive question - what is happening about 4096-byte sectors? Do we need to
> forward-plan?
They're fully supported already, but Linux defines a sector to be 512
bytes. So we multiply by 8 and divide by 8 a few times unnecessarily,
but it's not worth making sector size be a per-device property.
Good thought, though.
prev parent reply other threads:[~2020-05-05 18:01 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-05 11:55 [PATCH 0/4] eliminate SECTOR related magic numbers and duplicated conversions Zhen Lei
2020-05-05 11:55 ` [PATCH 1/4] block: Move SECTORS_PER_PAGE and SECTORS_PER_PAGE_SHIFT definitions into <linux/blkdev.h> Zhen Lei
2020-05-05 12:10 ` Matthew Wilcox
2020-05-06 4:06 ` Leizhen (ThunderTown)
2020-05-05 11:55 ` [PATCH 2/4] mm/swap: use SECTORS_PER_PAGE_SHIFT to clean up code Zhen Lei
2020-05-05 17:25 ` Matthew Wilcox
2020-05-06 1:33 ` Leizhen (ThunderTown)
2020-05-06 3:47 ` Leizhen (ThunderTown)
2020-05-06 9:16 ` Leizhen (ThunderTown)
2020-05-05 11:55 ` [PATCH 3/4] block: use SECTORS_PER_PAGE_SHIFT and SECTORS_PER_PAGE " Zhen Lei
2020-05-05 11:55 ` [PATCH 4/4] mtd: eliminate SECTOR related magic numbers Zhen Lei
2020-05-05 17:32 ` [PATCH 0/4] eliminate SECTOR related magic numbers and duplicated conversions antlists
2020-05-05 18:01 ` Matthew Wilcox [this message]
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