Re: [PATCH] exfat: preserve creation times during rename

[Jeff Layton]

On Tue, 2026-10-27 at 09:13 +0000, Hungyu Lin wrote:
> exfat_rename() resets the destination parent directory's i_crtime after
> every successful rename. A normal mv within that directory therefore
> changes its STATX_BTIME, and the new creation time is also written to
> disk. Moving a child does not recreate its parent directory.
> 
> The function also resets i_crtime on an overwritten target inode. An
> application holding an open file descriptor can observe its birth time
> change even though it still refers to the same inode.
> 
> Remove both creation-time updates. simple_rename_timestamp() already
> updates the modification and change times required by rename, while
> creation times should remain unchanged. Jeff Layton questioned these
> updates during the timestamp accessor conversion, but they remain in
> the current implementation.
> 
> Fixes: 5f2aa075070c ("exfat: add inode operations")
> Suggested-by: Jeff Layton <jlayton@xxxxxxxxxx>
> Link: https://lore.kernel.org/r/bb698e294b0d4dbbbad4b94048693360010b8010.camel@xxxxxxxxxx
> Signed-off-by: Hungyu Lin <dennylin0707@xxxxxxxxx>
> ---
>  fs/exfat/namei.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/fs/exfat/namei.c b/fs/exfat/namei.c
> index 68ddb9c5504f..d01280570f70 100644
> --- a/fs/exfat/namei.c
> +++ b/fs/exfat/namei.c
> @@ -1293,7 +1293,6 @@ static int exfat_rename(const struct mnt_idmap *idmap,
>  
>  	inode_inc_iversion(new_dir);
>  	simple_rename_timestamp(old_dir, old_dentry, new_dir, new_dentry);
> -	EXFAT_I(new_dir)->i_crtime = current_time(new_dir);
>  	exfat_truncate_inode_atime(new_dir);
>  	if (IS_DIRSYNC(new_dir) && size != i_size_read(new_dir))
>  		exfat_sync_inode(new_dir);
> @@ -1331,7 +1330,6 @@ static int exfat_rename(const struct mnt_idmap *idmap,
>  			exfat_warn(sb, "abnormal access to an inode dropped");
>  			WARN_ON(new_inode->i_nlink == 0);
>  		}
> -		EXFAT_I(new_inode)->i_crtime = current_time(new_inode);
>  	}
>  
>  unlock:

To be clear, i_crtime is equivalent to the btime, so it shouldn't
change on a rename.

Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>