Re: [PATCH] debugfs: fix mount options not being applied

[Eric Sandeen <sandeen@redhat.com>]

On 8/4/25 9:30 AM, Charalampos Mitrodimas wrote:
> Mount options (uid, gid, mode) are silently ignored when debugfs is
> mounted. This is a regression introduced during the conversion to the
> new mount API.
> 
> When the mount API conversion was done, the line that sets
> sb->s_fs_info to the parsed options was removed. This causes
> debugfs_apply_options() to operate on a NULL pointer.
> 
> As an example, with the bug the "mode" mount option is ignored:
> 
>   $ mount -o mode=0666 -t debugfs debugfs /tmp/debugfs_test
>   $ mount | grep debugfs_test
>   debugfs on /tmp/debugfs_test type debugfs (rw,relatime)
>   $ ls -ld /tmp/debugfs_test
>   drwx------ 25 root root 0 Aug  4 14:16 /tmp/debugfs_test

Argh. So, this looks a lot like the issue that got fixed for tracefs in:

e4d32142d1de tracing: Fix tracefs mount options

Let me look at this; tracefs & debugfs are quite similar, so perhaps
keeping the fix consistent would make sense as well but I'll dig
into it a bit more.

Thanks,
-Eric