linux-kernel - Re: [PATCH 1/2] resize.f2fs: add option to manually specify new overprovision

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Date:   Sun, 19 Jun 2022 08:01:38 +0800
From:   Chao Yu <chao@...nel.org>
To:     qixiaoyu1 <qxy65535@...il.com>, jaegeuk@...nel.org
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, liuchao12 <liuchao12@...omi.com>
Subject: Re: [PATCH 1/2] resize.f2fs: add option to manually specify new
 overprovision

On 2022/6/14 19:49, qixiaoyu1 wrote:
> From: liuchao12 <liuchao12@...omi.com>
> 
> Make.f2fs supports manually specifying overprovision, and we expect
> resize.f2fs to support it as well.
> 
> This change add a new '-o' option to manually specify overprovision.
> 
> Signed-off-by: liuchao12 <liuchao12@...omi.com>
> ---
>   fsck/main.c   |  8 ++++++--
>   fsck/resize.c | 12 ++++++++++--
>   2 files changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/fsck/main.c b/fsck/main.c
> index aef797e..3b4da0f 100644
> --- a/fsck/main.c
> +++ b/fsck/main.c
> @@ -121,7 +121,8 @@ void resize_usage()
>   	MSG(0, "[options]:\n");
>   	MSG(0, "  -d debug level [default:0]\n");
>   	MSG(0, "  -i extended node bitmap, node ratio is 20%% by default\n");
> -	MSG(0, "  -s safe resize (Does not resize metadata)");
> +	MSG(0, "  -o overprovision percentage [default:auto]\n");

Should update manual as well?

> +	MSG(0, "  -s safe resize (Does not resize metadata)\n");
>   	MSG(0, "  -t target sectors [default: device size]\n");
>   	MSG(0, "  -V print the version number and exit\n");
>   	exit(1);
> @@ -527,7 +528,7 @@ void f2fs_parse_options(int argc, char *argv[])
>   #endif
>   	} else if (!strcmp("resize.f2fs", prog)) {
>   #ifdef WITH_RESIZE
> -		const char *option_string = "d:fst:iV";
> +		const char *option_string = "d:fst:io:V";
>   
>   		c.func = RESIZE;
>   		while ((option = getopt(argc, argv, option_string)) != EOF) {
> @@ -561,6 +562,9 @@ void f2fs_parse_options(int argc, char *argv[])
>   			case 'i':
>   				c.large_nat_bitmap = 1;
>   				break;
> +			case 'o':
> +				c.new_overprovision = atof(optarg);
> +				break;
>   			case 'V':
>   				show_version(prog);
>   				exit(0);
> diff --git a/fsck/resize.c b/fsck/resize.c
> index f1b7701..d19c6fa 100644
> --- a/fsck/resize.c
> +++ b/fsck/resize.c
> @@ -146,12 +146,15 @@ safe_resize:
>   						get_sb(segs_per_sec));
>   
>   	/* Let's determine the best reserved and overprovisioned space */
> -	c.new_overprovision = get_best_overprovision(sb);
> +	if (c.new_overprovision == 0)
> +		c.new_overprovision = get_best_overprovision(sb);
> +
>   	c.new_reserved_segments =
>   		(2 * (100 / c.new_overprovision + 1) + 6) *
>   						get_sb(segs_per_sec);
>   
> -	if ((get_sb(segment_count_main) - 2) < c.new_reserved_segments ||
> +	if (c.new_overprovision == 0 ||

Should never be zero here? Otherwise above "100 / c.new_overprovision"
calculation will cause arithmetic exception.

Thanks,

> +		(get_sb(segment_count_main) - 2) < c.new_reserved_segments ||
>   		get_sb(segment_count_main) * blks_per_seg >
>   						get_sb(block_count)) {
>   		MSG(0, "\tError: Device size is not sufficient for F2FS volume, "
> @@ -476,6 +479,11 @@ static void rebuild_checkpoint(struct f2fs_sb_info *sbi,
>   	set_cp(overprov_segment_count, get_cp(overprov_segment_count) +
>   						get_cp(rsvd_segment_count));
>   
> +	DBG(0, "Info: Overprovision ratio = %.3lf%%\n", c.new_overprovision);
> +	DBG(0, "Info: Overprovision segments = %u (GC reserved = %u)\n",
> +					get_cp(overprov_segment_count),
> +					c.new_reserved_segments);
> +
>   	free_segment_count = get_free_segments(sbi);
>   	new_segment_count = get_newsb(segment_count_main) -
>   					get_sb(segment_count_main);