84f0cd9e83
step_into() tries to avoid grabbing and dropping mount references on the steps that do not involve crossing mountpoints (which is obviously the majority of cases). So it uses a local struct path with unusual refcounting rules - path.mnt is pinned if and only if it's not equal to nd->path.mnt. We used to have similar beasts all over the place and we had quite a few bugs crop up in their handling - it's easy to get confused when changing e.g. cleanup on failure exits (or adding a new check, etc.) Now that's mostly gone - the step_into() instance (which is what we need them for) is the only one left. It is exposed to mount traversal and it's (shortly) seen by pick_link(). Since pick_link() needs to store it in link stack, where the normal rules apply, it has to make sure that mount is pinned regardless of nd->path.mnt value. That's done on all calls of pick_link() and very early in those. Let's do that in the caller (step_into()) instead - that way the fewer places need to be aware of such struct path instances. 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 Restructured Text 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.