[PATCH v3] erofs-utils: lib: fix incorrect mtime under -Edot-omitted

[Gao Xiang]

On 2026/1/16 17:23, Yifan Zhao wrote:
> `-Edot-omitted` enables `-E48bits`, which requires specific
> configurations for g_sbi.{epoch, build_time}. Currently, the call to
> `erofs_sb_set_48bit()` occurs too late in the execution flow, causing
> the aforementioned logic to be bypassed and resulting in incorrect
> mtimes for all inodes.
> 
> This patch moves time initialization logic into `erofs_importer_init()`
> to resolve this issue.
> 
> Signed-off-by: Yifan Zhao <zhaoyifan28 at huawei.com>
> ---
>   lib/importer.c | 17 +++++++++++++++++
>   mkfs/main.c    | 15 ---------------
>   2 files changed, 17 insertions(+), 15 deletions(-)
> 
> diff --git a/lib/importer.c b/lib/importer.c
> index 958a433..b62ec20 100644
> --- a/lib/importer.c
> +++ b/lib/importer.c
> @@ -2,6 +2,7 @@
>   /*
>    * Copyright (C) 2025 Alibaba Cloud
>    */
> +#include <sys/time.h>
>   #include "erofs/importer.h"
>   #include "erofs/config.h"
>   #include "erofs/dedupe.h"
> @@ -43,6 +44,8 @@ int erofs_importer_init(struct erofs_importer *im)
>   	struct erofs_sb_info *sbi = im->sbi;
>   	struct erofs_importer_params *params = im->params;
>   	const char *subsys = NULL;
> +	struct timeval t;
> +	s64 mkfs_time = 0;
>   	int err;
>   
>   	erofs_importer_global_init();
> @@ -83,6 +86,20 @@ int erofs_importer_init(struct erofs_importer *im)
>   
>   	if (params->dot_omitted)
>   		erofs_sb_set_48bit(sbi);
> +
> +	sbi->fixed_nsec = 0;
> +	if (cfg.c_unix_timestamp != -1) {
> +		mkfs_time = cfg.c_unix_timestamp;

I mean we could

	if (params->mkfs_time != -1) {
		mkfs_time = params->mkfs_time;
		if (erofs_sb_has_48bit(sbi)) {
			sbi->epoch = max_t(s64, 0, mkfs_time - UINT32_MAX);
			sbi->build_time = mkfs_time - sbi->epoch;
		} else {
			sbi->epoch = mkfs_time;
		}

	}

> +	} else if (!gettimeofday(&t, NULL)) {
> +		mkfs_time = t.tv_sec;
> +	}
> +	if (erofs_sb_has_48bit(sbi)) {
> +		sbi->epoch = max_t(s64, 0, mkfs_time - UINT32_MAX);
> +		sbi->build_time = mkfs_time - sbi->epoch;
> +	} else {
> +		sbi->epoch = mkfs_time;
> +	}
> +
>   	return 0;
>   
>   out_err:
> diff --git a/mkfs/main.c b/mkfs/main.c
> index 620b1ed..6ee7f54 100644
> --- a/mkfs/main.c
> +++ b/mkfs/main.c
> @@ -1710,9 +1710,7 @@ int main(int argc, char **argv)
>   	};
>   	struct erofs_inode *root = NULL;
>   	bool tar_index_512b = false;
> -	struct timeval t;
>   	FILE *blklst = NULL;
> -	s64 mkfs_time = 0;
>   	int err;
>   	u32 crc;
>   
> @@ -1736,19 +1734,6 @@ int main(int argc, char **argv)
>   		goto exit;
>   	}
>   
> -	g_sbi.fixed_nsec = 0;
> -	if (cfg.c_unix_timestamp != -1) {
> -		mkfs_time = cfg.c_unix_timestamp;
> -	} else if (!gettimeofday(&t, NULL)) {
> -		mkfs_time = t.tv_sec;
> -	}
> -	if (erofs_sb_has_48bit(&g_sbi)) {
> -		g_sbi.epoch = max_t(s64, 0, mkfs_time - UINT32_MAX);
> -		g_sbi.build_time = mkfs_time - g_sbi.epoch;
> -	} else {
> -		g_sbi.epoch = mkfs_time;
> -	}

And here

	if (cfg.c_unix_timestamp != -1) {
		params->mkfs_time = cfg.c_unix_timestamp;
	else
		params->mkfs_time = !gettimeofday(&t, NULL) ...

	}

Thanks,
Gao Xiang

> -
>   	err = erofs_dev_open(&g_sbi, cfg.c_img_path, O_RDWR |
>   				(incremental_mode ? 0 : O_TRUNC));
>   	if (err) {