Re: [PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case

Jaegeuk Kim
2021-09-28T19:08:18Z

On 09/28, Chao Yu wrote:
> In f2fs_file_write_iter(), let's use f2fs_overwrite_io() to
> check whethere it is overwrite case, for such case, we can skip
> f2fs_preallocate_blocks() in order to avoid f2fs_do_map_lock(),
> which may be blocked by checkpoint() potentially.
>
> Signed-off-by: Chao Yu <chao@kernel.org>
> ---
> fs/f2fs/file.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 13deae03df06..51fecb2f4db5 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -4321,6 +4321,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
> preallocated = true;
> target_size = iocb->ki_pos + iov_iter_count(from);
>
> + if (f2fs_overwrite_io(inode, iocb->ki_pos,
> + iov_iter_count(from)))
> + goto write;

This calls f2fs_map_blocks() which can be duplicate, if it's not the overwirte
case. Do we have other benefit?

> +
> err = f2fs_preallocate_blocks(iocb, from);
> if (err) {
> out_err:
> --
> 2.32.0