[patch 16/39] remap_file_pages protection support: readd lock downgrading

From: Paolo 'Blaisorblade' Giarrusso <[EMAIL PROTECTED]> Even now, we'll sometimes take the write lock. So, in that case, we could downgrade it; after a tiny bit of thought, I've choosen doing that when we'll either do any I/O or we'll alter a lot of PTEs. About how much "a lot" is, I've copied

[patch 16/39] remap_file_pages protection support: readd lock downgrading

From: Paolo 'Blaisorblade' Giarrusso <[EMAIL PROTECTED]> Even now, we'll sometimes take the write lock. So, in that case, we could downgrade it; after a tiny bit of thought, I've choosen doing that when we'll either do any I/O or we'll alter a lot of PTEs. About how much "a lot" is, I've copied