Re: [PATCH] ntfs: compare streams_interface with mounted volume on remount

[liubaolin <liubaolin12138@163.com>]

在 2026/10/12 11:16, DaeMyung Kang 写道:
> During reconfiguration, fc->s_fs_info points to a newly allocated
> ntfs_volume. It does not contain the mounted volume's stream setting.
> Consequently, a windows mount rejects a remount with the same
> streams_interface=windows setting, but accepts streams_interface=none
> without changing the active pathname interface. This also breaks an
> ordinary read-only remount when the existing windows setting is passed
> again, for example from fstab.
> 
> Compare the requested setting with the mounted volume instead. Use its
> superblock when reporting an unsupported setting change.
> 
> Fixes: 2de2cdd9cc08 ("ntfs: add pathname access for named streams")
> Signed-off-by: DaeMyung Kang <charsyam@gmail.com>
> ---
>   fs/ntfs/super.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ntfs/super.c b/fs/ntfs/super.c
> index 242fb19ced2b..711e90be9382 100644
> --- a/fs/ntfs/super.c
> +++ b/fs/ntfs/super.c
> @@ -275,8 +275,8 @@ static int ntfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
>   			result.uint_32 == STREAMS_INTERFACE_WINDOWS;
>   
>   		if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE &&
> -		    NVolStreamsWindows(vol) != streams_windows) {
> -			ntfs_error(vol->sb,
> +		    NVolStreamsWindows(NTFS_SB(fc->root->d_sb)) != streams_windows) {
> +			ntfs_error(fc->root->d_sb,
>   				   "Cannot change streams_interface on remount.");
>   			return -EINVAL;
>   		}

Hi DaeMyung,

    The fix looks correct.
    However, vol->sb is NULL in the newly allocated volume, so 
ntfs_error() only logs the message. Changing the argument to 
fc->root->d_sb also invokes the mounted volume’s error-handling policy, 
which would trigger a panic on a read-write mount with errors=panic.

    This branch only rejects an unsupported option change during 
remount; it does not indicate filesystem corruption or an I/O error.

    Could we use ntfs_warning(fc->root->d_sb, ...) without triggering 
that policy?

Thanks,
Baolin.