The tool IWYU (include what you use) suggests to remove and add some
includes. This is only partial to avoid accidental build breakage, the
includes are entangled and will have to be cleaned in the future again.
Signed-off-by: David Sterba <dsterba@suse.com>
There's a group of functions that are related to opening filesystem in
various modes, this can be moved to a separate file.
Signed-off-by: David Sterba <dsterba@suse.com>