pagemap: introduce pagemap_entry_t without pmshift bits

These bits are always constant (== PAGE_SHIFT) and just occupy space in
the entry.  Moreover, in next patch we will need to report one more bit
in the pagemap, but all bits are already busy on it.

That said, describe the pagemap entry that has 6 more free zero bits.

Signed-off-by: Pavel Emelyanov <[email protected]>
Cc: Matt Mackall <[email protected]>
Cc: Xiao Guangrong <[email protected]>
Cc: Glauber Costa <[email protected]>
Cc: Marcelo Tosatti <[email protected]>
Cc: KOSAKI Motohiro <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
1 file changed