booked-page-flag.patch

[Andrew Morton <akpm@linux-foundation.org>]

Sorry, we're seriously, seriously, seriously short on flags in the page
struct and this patch is going to need one heck of a good case for it to be
acceptable.

Even then, we should put a lot of effort into finding some way of avoiding
adding that page flag.  One option might be to add a new radix-tree tag,
and defining it as "for filesytem usage".  Or use PG_checked (which should
be renamed to to PG_fs_misc) (if that doesn't conflict with ext4's existing
use of PG_checked).  Or use !PageMappedToDisk()?

These patches seem to have a number of issues - we should get them properly
commented and properly changelogged then get them on the wire for decent
review before investing too much in them, please.