On 7/1/22 8:19 AM, Jens Axboe wrote: > On 6/30/22 10:39 PM, Al Viro wrote: >> On Wed, Jun 01, 2022 at 02:01:41PM -0700, Stefan Roesch wrote: >>> This adds the async buffered write support to XFS. For async buffered >>> write requests, the request will return -EAGAIN if the ilock cannot be >>> obtained immediately. >> >> breaks generic/471... > > That test case is odd, because it makes some weird assumptions about > what RWF_NOWAIT means. Most notably that it makes it mean if we should > instantiate blocks or not. Where did those assumed semantics come from? > On the read side, we have clearly documented that it should "not wait > for data which is not immediately available". > > Now it is possible that we're returning a spurious -EAGAIN here when we > should not be. And that would be a bug imho. I'll dig in and see what's > going on. This is the timestamp update that needs doing which will now return -EAGAIN if IOCB_NOWAIT is set as it may block. I do wonder if we should just allow inode time updates with IOCB_NOWAIT, even on the io_uring side. Either that, or passed in RWF_NOWAIT semantics don't map completely to internal IOCB_NOWAIT semantics. At least in terms of what generic/471 is doing, but I'm not sure who came up with that and if it's established semantics or just some made up ones from whomever wrote that test. I don't think they make any sense, to be honest. -- Jens Axboe
