vm_page: define partial page invalidate

[dougm]

Summary

Two different functions in different files do the same thing - fill a partial page with zeroes. Add that functionality to vm_page.c and remove it elsewhere to avoid code duplication.

[markj]

sys/vm/vm_page.c

5090

I'd suggest noting that this function may temporarily drop the object lock.

5093

This name is somewhat strange. From the VM's perspective it's not invalidating the page (which normally would involve clearing bits from the page's valid mask), it's just zeroing a region of it. It's the tmpfs and shm objects that are being invalidated.

I'd suggest vm_page_grab_zero_partial() or something like that.

5130

I believe most of this function could be replaced by vm_page_grab_valid(&m, object, pindex, VM_PAGE_ALLOC_WAITOK);

[dougm]

Accept some suggestions from @markj.

sys/vm/vm_page.c

5130

When I recognize that, I'll be happy to make a change to exploit it, but I don't right now.

[markj]

sys/vm/vm_page.c

5090

5130

Sorry, you're right that it's not quite the right fit.

[alc]

sys/vm/vm_page.c

5108

This assertion is repeated below.