On Sat, Jul 24, 2021 at 03:41:21PM +0800, Wang Jianchao wrote:
> From: Wang Jianchao <wangjianchao@xxxxxxxxxxxx>
>
> There is no functional change in this patch but just split the
> codes, which serachs free block and does trim, into a new function
> ext4_try_to_trim_range. This is preparing for the following async
> backgroup discard.
>
> Reviewed-by: Andreas Dilger <adilger@xxxxxxxxx>
> Signed-off-by: Wang Jianchao <wangjianchao@xxxxxxxxxxxx>
> ---
> fs/ext4/mballoc.c | 102 ++++++++++++++++++++++++++--------------------
> 1 file changed, 57 insertions(+), 45 deletions(-)
>
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index 018d5d3c6eeb..e3844152a643 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -6218,6 +6218,54 @@ __acquires(bitlock)
> return ret;
> }
>
> +static int ext4_try_to_trim_range(struct super_block *sb,
> + struct ext4_buddy *e4b, ext4_grpblk_t start,
> + ext4_grpblk_t max, ext4_grpblk_t minblocks)
> +{
> + ext4_grpblk_t next, count, free_count;
> + void *bitmap;
> + int ret = 0;
> +
> + bitmap = e4b->bd_bitmap;
> + start = (e4b->bd_info->bb_first_free > start) ?
> + e4b->bd_info->bb_first_free : start;
> + count = 0;
> + free_count = 0;
> +
> + while (start <= max) {
> + start = mb_find_next_zero_bit(bitmap, max + 1, start);
> + if (start > max)
> + break;
> + next = mb_find_next_bit(bitmap, max + 1, start);
> +
> + if ((next - start) >= minblocks) {
> + ret = ext4_trim_extent(sb, start, next - start, e4b);
> + if (ret && ret != -EOPNOTSUPP)
> + break;
> + ret = 0;
> + count += next - start;
> + }
"ret" is only used inside the if statement, so this might be better as:
> + if ((next - start) >= minblocks) {
> + int ret = ext4_trim_extent(sb, start, next - start, e4b);
> +
> + if (ret && ret != -EOPNOTSUPP)
> + break;
> + count += next - start;
> + }
... and then drop the "int ret = 0" above.
Otherwise, looks good.
- Ted
