linux-kernel - Re: [f2fs-dev] [PATCH v2] f2fs: relax migratepage for atomic written page

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Message-ID: <4f92014b-5265-2c60-51a6-f80f34dd1418@kernel.org>
Date:   Fri, 7 Jul 2017 07:57:29 +0800
From:   Chao Yu <chao@...nel.org>
To:     Jaegeuk Kim <jaegeuk@...nel.org>, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH v2] f2fs: relax migratepage for atomic written
 page

On 2017/7/7 5:49, Jaegeuk Kim wrote:
> In order to avoid lock contention for atomic written pages, we'd better give
> EBUSY in f2fs_migrate_page when mode is asynchronous. We expect it will be
> released soon as transaction commits.
> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>

Reviewed-by: Chao Yu <yuchao0@...wei.com>

> ---
> 
> Change log from v1:
>  - return -EBUSY when mode is MIGRATE_ASYNC or MIGRATE_SYNC_LIGHT
> 
>  fs/f2fs/data.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 85ac3a63cce6..74c31cb203e2 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -2206,8 +2206,12 @@ int f2fs_migrate_page(struct address_space *mapping,
>  	BUG_ON(PageWriteback(page));
>  
>  	/* migrating an atomic written page is safe with the inmem_lock hold */
> -	if (atomic_written && !mutex_trylock(&fi->inmem_lock))
> -		return -EAGAIN;
> +	if (atomic_written) {
> +		if (mode != MIGRATE_SYNC)
> +			return -EBUSY;
> +		if (!mutex_trylock(&fi->inmem_lock))
> +			return -EAGAIN;
> +	}
>  
>  	/*
>  	 * A reference is expected if PagePrivate set when move mapping,
>