Re: [PATCH] fat: fix parent link count when replacing a sibling directory

[OGAWA Hirofumi]

Hungyu Lin <dennylin0707@xxxxxxxxx> writes:

> vfat_rename() and do_msdos_rename() adjust parent link counts only when
> updating the dotdot entry for a move between different parents. Replacing
> an existing empty directory in the same parent also removes a
> subdirectory, but leaves the parent's link count unchanged.
>
> For example, renaming one of two sibling directories over the other
> leaves the parent with four links instead of three. stat and ls report
> the stale count, and find -links 3 does not match the parent.
>
> Drop the parent's link count for this case after the source entry has
> been removed successfully. Leave cross-parent renames, regular files
> and the existing error paths unchanged.
>
> Signed-off-by: Hungyu Lin <dennylin0707@xxxxxxxxx>

Looks good. Thanks.

Acked-by: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>

> ---
>  fs/fat/namei_msdos.c | 2 ++
>  fs/fat/namei_vfat.c  | 2 ++
>  2 files changed, 4 insertions(+)
>
> diff --git a/fs/fat/namei_msdos.c b/fs/fat/namei_msdos.c
> index c7500c2859e0..570dd75dd275 100644
> --- a/fs/fat/namei_msdos.c
> +++ b/fs/fat/namei_msdos.c
> @@ -565,6 +565,8 @@ static int do_msdos_rename(struct inode *old_dir, unsigned char *old_name,
>  		(void)sync_inode_metadata(old_dir, 1);
>  
>  	if (new_inode) {
> +		if (is_dir && old_dir == new_dir)
> +			drop_nlink(old_dir);
>  		drop_nlink(new_inode);
>  		if (is_dir)
>  			drop_nlink(new_inode);
> diff --git a/fs/fat/namei_vfat.c b/fs/fat/namei_vfat.c
> index ff7652bf0410..d7e2df5bf7e5 100644
> --- a/fs/fat/namei_vfat.c
> +++ b/fs/fat/namei_vfat.c
> @@ -1011,6 +1011,8 @@ static int vfat_rename(struct inode *old_dir, struct dentry *old_dentry,
>  	vfat_update_dir_metadata(old_dir, &ts);
>  
>  	if (new_inode) {
> +		if (is_dir && old_dir == new_dir)
> +			drop_nlink(old_dir);
>  		drop_nlink(new_inode);
>  		if (is_dir)
>  			drop_nlink(new_inode);

-- 
OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>