Re: [f2fs-dev] [PATCH] f2fs: compress: avoid unnecessary check in f2fs_prepare_compress_overwrite

[Gao Xiang <hsiangkao@redhat.com>]

On Mon, Apr 26, 2021 at 10:11:53AM +0800, Fengnan Chang wrote:
> when write compressed file with O_TRUNC, there will be a lot of
> unnecessary check valid blocks in f2fs_prepare_compress_overwrite,
> especially when written in page size, remove it.
> 
> Signed-off-by: Fengnan Chang <changfengnan@vivo.com>

Even though I didn't look into the whole thing,
my reaction here is roughly how to handle fallocate with
keep size? Does it work as expected?

> ---
>  fs/f2fs/data.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index cf935474ffba..9c3b0849f35e 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -3270,6 +3270,7 @@ static int f2fs_write_begin(struct file *file, struct address_space *mapping,
>  	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
>  	struct page *page = NULL;
>  	pgoff_t index = ((unsigned long long) pos) >> PAGE_SHIFT;
> +	pgoff_t end = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
>  	bool need_balance = false, drop_atomic = false;
>  	block_t blkaddr = NULL_ADDR;
>  	int err = 0;
> @@ -3306,6 +3307,9 @@ static int f2fs_write_begin(struct file *file, struct address_space *mapping,
> 
>  		*fsdata = NULL;
> 
> +		if (index >= end)
> +			goto repeat;
> +
>  		ret = f2fs_prepare_compress_overwrite(inode, pagep,
>  							index, fsdata);
>  		if (ret < 0) {
> --
> 2.29.0



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