This is my personal opinion, but when I look at the log on the guest side, I can read that 0 can be read even though I wrote it. [1979.965517] [C1] BTRFS error (device vda2): bdev / dev / vda2 errs: wr 897, rd 0, flush 0, corrupt 0, gen 0 The opposite of Use after free, isn't it read before the writing is reflected?