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Message-ID: <20201009213434.GA839@sol.localdomain>
Date: Fri, 9 Oct 2020 14:34:34 -0700
From: Eric Biggers <ebiggers@...nel.org>
To: ira.weiny@...el.com
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Subject: Re: [PATCH RFC PKS/PMEM 22/58] fs/f2fs: Utilize new kmap_thread()
On Fri, Oct 09, 2020 at 12:49:57PM -0700, ira.weiny@...el.com wrote:
> From: Ira Weiny <ira.weiny@...el.com>
>
> The kmap() calls in this FS are localized to a single thread. To avoid
> the over head of global PKRS updates use the new kmap_thread() call.
>
> Cc: Jaegeuk Kim <jaegeuk@...nel.org>
> Cc: Chao Yu <chao@...nel.org>
> Signed-off-by: Ira Weiny <ira.weiny@...el.com>
> ---
> fs/f2fs/f2fs.h | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index d9e52a7f3702..ff72a45a577e 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -2410,12 +2410,12 @@ static inline struct page *f2fs_pagecache_get_page(
>
> static inline void f2fs_copy_page(struct page *src, struct page *dst)
> {
> - char *src_kaddr = kmap(src);
> - char *dst_kaddr = kmap(dst);
> + char *src_kaddr = kmap_thread(src);
> + char *dst_kaddr = kmap_thread(dst);
>
> memcpy(dst_kaddr, src_kaddr, PAGE_SIZE);
> - kunmap(dst);
> - kunmap(src);
> + kunmap_thread(dst);
> + kunmap_thread(src);
> }
Wouldn't it make more sense to switch cases like this to kmap_atomic()?
The pages are only mapped to do a memcpy(), then they're immediately unmapped.
- Eric
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