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From:   Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>
To:     "ira.weiny@intel.com" <ira.weiny@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        "clm@fb.com" <clm@fb.com>,
        "josef@toxicpanda.com" <josef@toxicpanda.com>,
        "dsterba@suse.com" <dsterba@suse.com>
CC:     Boris Pismenny <borisp@mellanox.com>,
        Or Gerlitz <gerlitz.or@gmail.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Matthew Wilcox <willy@infradead.org>,
        "hch@infradead.org" <hch@infradead.org>,
        Dan Williams <dan.j.williams@intel.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Eric Biggers <ebiggers@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH 1/4] mm/highmem: Lift memcpy_[to|from]_page to core
Thread-Topic: [PATCH 1/4] mm/highmem: Lift memcpy_[to|from]_page to core
Thread-Index: AQHW/DCr64Y1yB8xakqJU9Z0zyt3KQ==
Date:   Sun, 7 Feb 2021 01:46:47 +0000
Message-ID: <BYAPR04MB49655E5BDB24A108FEFFE9C486B09@BYAPR04MB4965.namprd04.prod.outlook.com>
References: <20210205232304.1670522-1-ira.weiny@intel.com>
 <20210205232304.1670522-2-ira.weiny@intel.com>
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On 2/5/21 18:35, ira.weiny@intel.com wrote:=0A=
> +static inline void memmove_page(struct page *dst_page, size_t dst_off,=
=0A=
> +			       struct page *src_page, size_t src_off,=0A=
> +			       size_t len)=0A=
> +{=0A=
> +	char *dst =3D kmap_local_page(dst_page);=0A=
> +	char *src =3D kmap_local_page(src_page);=0A=
> +=0A=
> +	BUG_ON(dst_off + len > PAGE_SIZE || src_off + len > PAGE_SIZE);=0A=
> +	memmove(dst + dst_off, src + src_off, len);=0A=
> +	kunmap_local(src);=0A=
> +	kunmap_local(dst);=0A=
> +}=0A=
> +=0A=
> +static inline void memcpy_from_page(char *to, struct page *page, size_t =
offset, size_t len)=0A=
How about following ?=0A=
static inline void memcpy_from_page(char *to, struct page *page, size_t=0A=
offset,=0A=
                                    size_t len)  =0A=
> +{=0A=
> +	char *from =3D kmap_local_page(page);=0A=
> +=0A=
> +	BUG_ON(offset + len > PAGE_SIZE);=0A=
> +	memcpy(to, from + offset, len);=0A=
> +	kunmap_local(from);=0A=
> +}=0A=
> +=0A=
> +static inline void memcpy_to_page(struct page *page, size_t offset, cons=
t char *from, size_t len)=0A=
How about following ?=0A=
static inline void memcpy_to_page(struct page *page, size_t offset,=0A=
                                  const char *from, size_t len)=0A=
> +{=0A=
> +	char *to =3D kmap_local_page(page);=0A=
> +=0A=
> +	BUG_ON(offset + len > PAGE_SIZE);=0A=
> +	memcpy(to + offset, from, len);=0A=
> +	kunmap_local(to);=0A=
> +}=0A=
> +=0A=
> +static inline void memset_page(struct page *page, size_t offset, int val=
, size_t len)=0A=
How about following ?=0A=
static inline void memset_page(struct page *page, size_t offset, int val,=
=0A=
                               size_t len)  =0A=
> +{=0A=
> +	char *addr =3D kmap_local_page(page);=0A=
> +=0A=
> +	BUG_ON(offset + len > PAGE_SIZE);=0A=
> +	memset(addr + offset, val, len);=0A=
> +	kunmap_local(addr);=0A=
> +}=0A=
> +=0A=