5f6a15bcbe
semantics. now: (1) dirty file systems will always be checked; nothing new there. (2) if not '-f' clean file systems will _NEVER_ be checked, i.e. they won't be checked even if -p isn't specified. This allows one to 'fsck -p ; fsck' to preen, then clean up anything that 'fsck -p' barfs on, without waiting for the clean file systems to be checked again. (3) if '-f' clean file systems will ALWAYS be checked. This allows people to put 'fsck -fp' into /etc/rc on systems where they're leery of the FS clean flag state, need the extra reliability, and can afford time 'wasted' in checks. The assumption made here is that if a file system is marked clean, it _IS CLEAN_, really, and shouldn't be checked unless fsck is explicitly told to (with -f). This should be a valid assumption, but may not be in the presence of file system bugs. Documentation updated to note '-f'.