[git pull] regression fix for mount propagation in detached trees

[Al Viro <viro@zeniv.linux.org.uk>]

6.15 allowed mount propagation to destinations in detached trees;
unfortunately, that breaks existing userland, so the old behaviour
needs to be restored.

It's not exactly a revert - original behaviour had a bug, where existence
of detached tree might disrupt propagation between locations not in
detached trees.  Thankfully, userland did not upon that bug, so we
want to keep the fix.

The following changes since commit d1ddc6f1d9f0cf887834eb54a5a68bbfeec1bb77:

  fix IS_MNT_PROPAGATING uses (2025-05-09 18:06:27 -0400)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git tags/pull-fixes

for you to fetch changes up to 3b5260d12b1fe76b566fe182de8abc586b827ed0:

  Don't propagate mounts into detached trees (2025-05-26 17:35:32 -0400)

----------------------------------------------------------------
6.15 behaviour wrt mount propagation into detached trees breaks userland.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

----------------------------------------------------------------
Al Viro (1):
      Don't propagate mounts into detached trees

 fs/mount.h     |  5 -----
 fs/namespace.c | 15 ++-------------
 fs/pnode.c     |  4 ++--
 3 files changed, 4 insertions(+), 20 deletions(-)