Dave Chinner <david@xxxxxxxxxxxxx> writes: > That's what I expected - I would have been surprised if you found > problems across multiple filesystems... How do the other filesystems know they don't need to issue a flush? While this particular method of reproducing the problem ( sync without touching the filesystem ) only shows on ext4, I'm not sure this isn't still a broader problem. Say that a program writes some data to a file. Due to cache pressure, the dirty pages get written to the disk. Some time later, the disk is runtime suspended ( which flushes its write cache ). After that, someone does some kind of sync ( whole fs or individual file ). Doesn't the FS *have* to issue a flush at that point? Even though there is nothing in the disk's cache, the FS doesn't know that.
