[PATCH V2] ubifs: Convert ubifs to use the new mount API

[Eric Sandeen]

On 10/2/24 11:58 AM, Eric Sandeen wrote:
> From: David Howells <dhowells at redhat.com>
> 
> Convert the ubifs filesystem to the new internal mount API as the old
> one will be obsoleted and removed.  This allows greater flexibility in
> communication of mount parameters between userspace, the VFS and the
> filesystem.
> 
> See Documentation/filesystems/mount_api.txt for more information.
> 
> Signed-off-by: David Howells <dhowells at redhat.com>
> Co-developed-by: Eric Sandeen <sandeen at redhat.com>
> [sandeen: forward-port old patch, use dedicated context struct]]
> Signed-off-by: Eric Sandeen <sandeen at redhat.com>
> cc: Richard Weinberger <richard at nod.at>
> cc: Zhihao Cheng <chengzhihao1 at huawei.com>
> cc: linux-mtd at lists.infradead.org
> ---

Again, this is a forward port of dhowells' patch but with some significant
modifications, as requested.

The primary change is that init_fs_context no longer allocates the
entire ubifs_info; instead, it now uses a mount-option specific context
structure that hangs off fc->fs_private and transfers parsed options from
there into the ubifs_info structure members after parsing.

Other minor changes include fixes to argument descriptions in comments,
and whitespace tidyup.

I tested this as best I could using mtdram, though I did not exercise
valid auth_key and/or auth_hash_name mount options, or test beyond
validating that random combinations of mount options yielded the same
success/failure results, and the same /proc/mounts results, as before
the patch.

Thanks,
-Eric