Which obviously can be used to "ignore" the mounts we do not want or
need to dump. The user should know what he does.

Note: this patch changes parse_mountinfo() to check should_skip_mount().
This is because imo we want to filter out the unwanted mounts asap, af
if they do not exist. This increases the chances the dumping will fail
if something else depends on this mount. Say, another mountpoint or an
opened file.

Perhaps it makes sense to teach should_skip_mount() to use fnmatch()
and/or look at the optional "(fs|mnt)=" prefix to skip by fsname too.

To me it would be better to force the user of this option to understand
what it does. Say, if "dump" fails because the child mount can't find
the skipped parent, he should add another --skip-mnt option or do not
dump. Otherwise, if we do this automagically the user can probably be
surpised, he might even miss the fact that we skip more than he asked.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>