It would be a grave error to call it without the page lock.
That's just a question of how we interpret PG_uptodate. If it means:
the page contains data that is valid, or was valid at some point in
time, then an invalidated or truncated page can be uptodate.
You rely on page being !PageUptodate() after being invalidated? Why
can't you check page->mapping instead (as everything else does)?
Yes.
No, instead of returning a short count, it is now returning old
content.
Miklos
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