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Date:   Fri, 21 Apr 2023 10:23:54 +0800
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Subject: Re: [f2fs-dev] [PATCH] f2fs: use cow inode data when updating atomic
 write
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To:     Daeho Jeong <daeho43@gmail.com>, linux-kernel@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net, kernel-team@android.com
Cc:     Daeho Jeong <daehojeong@google.com>
References: <20230418175206.3282328-1-daeho43@gmail.com>
From:   Chao Yu <chao@kernel.org>
In-Reply-To: <20230418175206.3282328-1-daeho43@gmail.com>
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On 2023/4/19 1:52, Daeho Jeong wrote:
> From: Daeho Jeong <daehojeong@google.com>
> 
> Need to use cow inode data content instead of the one in the original
> inode, when we try to write the already updated atomic write files.
> 

Miss a fixes line?

Otherwise it looks good to me.

Thanks

> Signed-off-by: Daeho Jeong <daehojeong@google.com>
> ---
>   fs/f2fs/data.c | 15 ++++++++++-----
>   1 file changed, 10 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 8df225014304..7165b1202f53 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -3491,7 +3491,7 @@ static int __reserve_data_block(struct inode *inode, pgoff_t index,
>   
>   static int prepare_atomic_write_begin(struct f2fs_sb_info *sbi,
>   			struct page *page, loff_t pos, unsigned int len,
> -			block_t *blk_addr, bool *node_changed)
> +			block_t *blk_addr, bool *node_changed, bool *use_cow)
>   {
>   	struct inode *inode = page->mapping->host;
>   	struct inode *cow_inode = F2FS_I(inode)->cow_inode;
> @@ -3505,10 +3505,12 @@ static int prepare_atomic_write_begin(struct f2fs_sb_info *sbi,
>   
>   	/* Look for the block in COW inode first */
>   	err = __find_data_block(cow_inode, index, blk_addr);
> -	if (err)
> +	if (err) {
>   		return err;
> -	else if (*blk_addr != NULL_ADDR)
> +	} else if (*blk_addr != NULL_ADDR) {
> +		*use_cow = true;
>   		return 0;
> +	}
>   
>   	if (is_inode_flag_set(inode, FI_ATOMIC_REPLACE))
>   		goto reserve_block;
> @@ -3538,6 +3540,7 @@ static int f2fs_write_begin(struct file *file, struct address_space *mapping,
>   	struct page *page = NULL;
>   	pgoff_t index = ((unsigned long long) pos) >> PAGE_SHIFT;
>   	bool need_balance = false;
> +	bool use_cow = false;
>   	block_t blkaddr = NULL_ADDR;
>   	int err = 0;
>   
> @@ -3597,7 +3600,7 @@ static int f2fs_write_begin(struct file *file, struct address_space *mapping,
>   
>   	if (f2fs_is_atomic_file(inode))
>   		err = prepare_atomic_write_begin(sbi, page, pos, len,
> -					&blkaddr, &need_balance);
> +					&blkaddr, &need_balance, &use_cow);
>   	else
>   		err = prepare_write_begin(sbi, page, pos, len,
>   					&blkaddr, &need_balance);
> @@ -3637,7 +3640,9 @@ static int f2fs_write_begin(struct file *file, struct address_space *mapping,
>   			f2fs_handle_error(sbi, ERROR_INVALID_BLKADDR);
>   			goto fail;
>   		}
> -		err = f2fs_submit_page_read(inode, page, blkaddr, 0, true);
> +		err = f2fs_submit_page_read(use_cow ?
> +				F2FS_I(inode)->cow_inode : inode, page,
> +				blkaddr, 0, true);
>   		if (err)
>   			goto fail;
>