On Fri, Feb 19, 2021 at 02:22:01PM +0000, Matthew Wilcox wrote:

In the last decade, nobody's tried to fix it in mainline that I know of.
As I said, some vendors have tried to fix it in their NAS products,
but I don't know where to find that patch any more.

Arnd found it for me.

https://sourceforge.net/projects/dsgpl/files/Synology%20NAS%20GPL%20Source/25426branch/alpine-source/linux-3.10.x-bsp.txz/download

They've done a perfect job of making the source available while making it
utterly dreadful to extract anything useful from.

 16084 files changed, 1322769 insertions(+), 285257 deletions(-)

It's full of gratuitous whitespace changes to files that definitely
aren't used (arch/alpha?  really?) and they've stripped out a lot of
comments that they didn't need to touch.

Forward porting a patch from 10 years ago wouldn't be easy, even if
they hadn't tried very hard to obfuscate their patch.  I don't think
this will be a fruitful line of inquiry.