[PATCH] erofs: correct FSDAX detection

[Chao Yu]

On 11/17/2025 7:57 PM, Gao Xiang wrote:
> The detection of the primary device is skipped incorrectly
> if the multiple or flattened feature is enabled.
> 
> It also fixes the FSDAX misdetection for non-block extra blobs.
> 
> Fixes: c6993c4cb918 ("erofs: Fallback to normal access if DAX is not supported on extra device")
> Reported-by: syzbot+31b8fb02cb8a25bd5e78 at syzkaller.appspotmail.com
> Closes: https://lore.kernel.org/r/691af9f6.a70a0220.3124cb.0097.GAE@google.com
> Cc: Yuezhang Mo <Yuezhang.Mo at sony.com>
> Signed-off-by: Gao Xiang <hsiangkao at linux.alibaba.com>

Reviewed-by: Chao Yu <chao at kernel.org>

Thanks,