From: Matthew Wilcox <willy@infradead.org>
To: zhouxianrong <zhouxianrong@huawei.com>
Cc: Minchan Kim <minchan@kernel.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
akpm@linux-foundation.org, sergey.senozhatsky@gmail.com,
iamjoonsoo.kim@lge.com, ngupta@vflare.org,
Mi.Sophia.Wang@huawei.com, zhouxiyu@huawei.com,
weidu.du@huawei.com, zhangshiming5@huawei.com,
won.ho.park@huawei.com
Subject: Re: [PATCH] mm: extend zero pages to same element pages for zram
Date: Mon, 6 Feb 2017 06:14:48 -0800 [thread overview]
Message-ID: <20170206141448.GF2267@bombadil.infradead.org> (raw)
In-Reply-To: <2f6e188c-5358-eeab-44ab-7634014af651@huawei.com>
On Mon, Feb 06, 2017 at 09:28:18AM +0800, zhouxianrong wrote:
> > > +static inline void zram_fill_page_partial(char *ptr, unsigned int size,
> > > + unsigned long value)
> > > +{
> > > + int i;
> > > + unsigned long *page;
> > > +
> > > + if (likely(value == 0)) {
> > > + memset(ptr, 0, size);
> > > + return;
> > > + }
> > > +
> > > + i = ((unsigned long)ptr) % sizeof(*page);
> > > + if (i) {
> > > + while (i < sizeof(*page)) {
> > > + *ptr++ = (value >> (i * 8)) & 0xff;
> > > + --size;
> > > + ++i;
> > > + }
> > > + }
> > > +
> >
> > I don't think we need this part because block layer works with sector
> > size or multiple times of it so it must be aligned unsigned long.
>
> Minchan and Matthew Wilcox:
>
> 1. right, but users could open /dev/block/zram0 file and do any read operations.
But any such read operation would go through the page cache, so will
be page aligned. Unless they do an O_DIRECT operation, in which case
it must be aligned to block size. Please, try it. I/Os which are not
aligned should be failed long before they reach your driver.
next prev parent reply other threads:[~2017-02-06 14:14 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-06 8:42 [PATCH] mm: extend zero pages to same element pages for zram zhouxianrong
2017-01-09 23:41 ` Minchan Kim
2017-01-13 4:24 ` Sergey Senozhatsky
2017-01-13 6:23 ` Minchan Kim
2017-01-13 6:36 ` Sergey Senozhatsky
2017-01-13 6:47 ` Minchan Kim
2017-01-13 7:02 ` Sergey Senozhatsky
2017-01-13 8:03 ` Minchan Kim
2017-01-13 8:29 ` zhouxianrong
2017-01-21 8:43 ` Sergey Senozhatsky
2017-01-22 2:58 ` zhouxianrong
2017-01-22 4:45 ` Sergey Senozhatsky
2017-01-23 2:58 ` Joonsoo Kim
2017-01-23 3:32 ` zhouxianrong
2017-01-23 4:03 ` Sergey Senozhatsky
2017-01-23 6:27 ` Joonsoo Kim
2017-01-23 7:13 ` Sergey Senozhatsky
2017-01-23 7:40 ` Minchan Kim
2017-01-24 7:58 ` zhouxianrong
2017-01-25 1:29 ` Minchan Kim
2017-01-25 1:32 ` Sergey Senozhatsky
2017-01-25 2:48 ` Matthew Wilcox
2017-01-25 4:18 ` Sergey Senozhatsky
2017-01-25 4:51 ` Minchan Kim
2017-01-25 5:38 ` Sergey Senozhatsky
2017-01-25 5:44 ` Minchan Kim
2017-01-23 6:26 ` Matthew Wilcox
2017-01-23 6:32 ` 答复: " zhouxianrong
2017-02-03 8:34 ` zhouxianrong
2017-02-03 8:42 ` zhouxianrong
2017-02-03 15:33 ` Matthew Wilcox
2017-02-04 3:33 ` zhouxianrong
2017-02-05 14:21 ` Minchan Kim
2017-02-06 1:28 ` zhouxianrong
2017-02-06 14:14 ` Matthew Wilcox [this message]
2017-02-06 23:48 ` Minchan Kim
2017-02-07 2:20 ` zhouxianrong
2017-02-07 2:54 ` Minchan Kim
2017-02-07 3:24 ` zhouxianrong
2017-02-07 4:57 ` Minchan Kim
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