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725ab435ff
the only difference between it and CL_SLAVE is in this predicate
in clone_mnt():
if ((flag & CL_SLAVE) ||
((flag & CL_SHARED_TO_SLAVE) && IS_MNT_SHARED(old))) {
However, in case of CL_SHARED_TO_SLAVE we have not allocated any
mount group ids since the time we'd grabbed namespace_sem, so
IS_MNT_SHARED() is equivalent to non-zero ->mnt_group_id. And
in case of CL_SLAVE old has come either from the original tree,
which had ->mnt_group_id allocated for all nodes or from result
of sequence of CL_MAKE_SHARED or CL_MAKE_SHARED|CL_SLAVE copies,
ultimately going back to the original tree. In both cases we are
guaranteed that old->mnt_group_id will be non-zero.
In other words, the predicate is always equal to
(flags & (CL_SLAVE | CL_SHARED_TO_SLAVE)) && old->mnt_group_id
and with that replacement CL_SLAVE and CL_SHARED_TO_SLAVE have exact
same behaviour.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.