[PATCH] erofs-utils: mkfs: fix image reproducibility of `-E(all-)fragments`

[Hongbo Li]

Hi, Xiang,

On 2025/5/31 8:29, Gao Xiang wrote:
> The timestamp of the packed inode should be fixed to the build time.
> 
> Fixes: 9fa9b017f773 ("erofs-utils: mkfs: support fragments")
> Signed-off-by: Gao Xiang <hsiangkao at linux.alibaba.com>
> ---
>   lib/inode.c | 14 ++++++++++----
>   1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/inode.c b/lib/inode.c
> index 7a10624..ca49a80 100644
> --- a/lib/inode.c
> +++ b/lib/inode.c
> @@ -910,7 +910,8 @@ out:
>   	return 0;
>   }
>   
> -static bool erofs_should_use_inode_extended(struct erofs_inode *inode)
> +static bool erofs_should_use_inode_extended(struct erofs_inode *inode,
> +					    const char *path)
>   {
>   	if (cfg.c_force_inodeversion == FORCE_INODE_EXTENDED)
>   		return true;
> @@ -924,7 +925,8 @@ static bool erofs_should_use_inode_extended(struct erofs_inode *inode)
>   		return true;
>   	if (inode->i_nlink > USHRT_MAX)
>   		return true;
> -	if ((inode->i_mtime != inode->sbi->build_time ||
> +	if (path != EROFS_PACKED_INODE &&
> +	    (inode->i_mtime != inode->sbi->build_time ||
>   	     inode->i_mtime_nsec != inode->sbi->build_time_nsec) &&
>   	    !cfg.c_ignore_mtime)
>   		return true;
> @@ -1016,6 +1018,10 @@ int __erofs_fill_inode(struct erofs_inode *inode, struct stat *st,
>   		erofs_err("gid overflow @ %s", path);
>   	inode->i_gid += cfg.c_gid_offset;
>   
> +	if (path == EROFS_PACKED_INODE) {
> +		inode->i_mtime = sbi->build_time;
> +		inode->i_mtime_nsec = 0;
> +	}
>   	inode->i_mtime = st->st_mtime;
>   	inode->i_mtime_nsec = ST_MTIM_NSEC(st);

Should we put the condition in here? Because it will be reassigned if we 
do like this.

And what about assigning sbi->build_time_nsec to inode->i_mtime_nsec 
like the FIXED case?

Thanks,
Hongbo

>   
> @@ -1065,7 +1071,7 @@ static int erofs_fill_inode(struct erofs_inode *inode, struct stat *st,
>   	if (!inode->i_srcpath)
>   		return -ENOMEM;
>   
> -	if (erofs_should_use_inode_extended(inode)) {
> +	if (erofs_should_use_inode_extended(inode, path)) {
>   		if (cfg.c_force_inodeversion == FORCE_INODE_COMPACT) {
>   			erofs_err("file %s cannot be in compact form",
>   				  inode->i_srcpath);
> @@ -1610,7 +1616,7 @@ static int erofs_rebuild_handle_inode(struct erofs_inode *inode,
>   	erofs_update_progressinfo("Processing %s ...", trimmed);
>   	free(trimmed);
>   
> -	if (erofs_should_use_inode_extended(inode)) {
> +	if (erofs_should_use_inode_extended(inode, inode->i_srcpath)) {
>   		if (cfg.c_force_inodeversion == FORCE_INODE_COMPACT) {
>   			erofs_err("file %s cannot be in compact form",
>   				  inode->i_srcpath);