977e5f8ed0
Split the usage count on the afs_server struct to have an active count that
registers who's actually using it separately from the reference count on
the object.
This allows a future patch to dispatch polling probes without advancing the
"unuse" time into the future each time we emit a probe, which would
otherwise prevent unused server records from expiring.
Included in this:
(1) The latter part of afs_destroy_server() in which the RCU destruction
of afs_server objects is invoked and the outstanding server count is
decremented is split out into __afs_put_server().
(2) afs_put_server() now calls __afs_put_server() rather then setting the
management timer.
(3) The calls begun by afs_fs_give_up_all_callbacks() and
afs_fs_get_capabilities() can now take a ref on the server record, so
afs_destroy_server() can just drop its ref and needn't wait for the
completion of these calls. They'll put the ref when they're done.
(4) Because of (3), afs_fs_probe_done() no longer needs to wake up
afs_destroy_server() with server->probe_outstanding.
(5) afs_gc_servers can be simplified. It only needs to check if
server->active is 0 rather than playing games with the refcount.
(6) afs_manage_servers() can propose a server for gc if usage == 0 rather
than if ref == 1. The gc is effected by (5).
Signed-off-by: David Howells <dhowells@redhat.com>
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.