netfs, fscache: Move /proc/fs/fscache to /proc/fs/netfs and put in a symlink

Rename /proc/fs/fscache to "netfs" and make a symlink from fscache to that.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: Christian Brauner <christian@brauner.io>
cc: linux-fsdevel@vger.kernel.org
cc: linux-cachefs@redhat.com

netfs, fscache: Combine fscache with netfs

Now that the fscache code is moved to be colocated with the netfslib code
so that they combined into one module, do the combining.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: Christian Brauner <christian@brauner.io>
cc: linux-fsdevel@vger.kernel.org
cc: linux-cachefs@redhat.com
cc: linux-nfs@vger.kernel.org,
cc: linux-erofs@lists.ozlabs.org

netfs, fscache: Move fs/fscache/* into fs/netfs/

There's a problem with dependencies between netfslib and fscache as each
wants to access some functions of the other. Deal with this by moving
fs/fscache/* into fs/netfs/ and renaming those files to begin with
"fscache-".

For the moment, the moved files are changed as little as possible and an
fscache module is still built. A subsequent patch will integrate them.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: Christian Brauner <christian@brauner.io>
cc: linux-fsdevel@vger.kernel.org
cc: linux-cachefs@redhat.com