On Mon, 19 Jul 2021, Christoph Hellwig wrote:

On Thu, Jul 15, 2021 at 02:01:11PM -0400, Josef Bacik wrote:

quoted

This is not a workable solution.  It's not a matter of simply tying into
existing infrastructure, we'd have to completely rework how the VFS deals
with this stuff in order to be reasonable.  And when I brought this up to Al
he told me I was insane and we absolutely had to have a different SB for
every vfsmount, which means we can't use vfsmount for this, which means we
don't have any other options.  Thanks,

Then fix the problem another way.  The problem is known, old and keeps
breaking stuff.  Don't paper over it, fix it. 

Do you have any pointers to other breakage caused by this particular
behaviour of btrfs? It would to have all requirements clearly on the
table while designing a solution.

Thanks,
NeilBrown