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

[DaeMyung Kang <charsyam@gmail.com>]

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;
 		}
-- 
2.43.0