Hi, On 2023-04-09 13:55:33 +1200, Thomas Munro wrote: > I think that particular thing might relate to modifications of the > user buffer while a write is in progress (breaking btrfs's internal > checksums). I don't think we should ever do that ourselves (not least > because it'd break our own checksums). We lock the page during the > write so no one can do that, and then we sleep in a synchronous > syscall.
Oh, but we actually *do* modify pages while IO is going on. I wonder if you hit the jack pot here. The content lock doesn't prevent hint bit writes. That's why we copy the page to temporary memory when computing checksums. I think we should modify the test to enable checksums - if the problem goes away, then it's likely to be related to modifying pages while an O_DIRECT write is ongoing... Greetings, Andres Freund
