On 10/10/22 8:54 PM, Jens Axboe wrote:
> On 10/10/22 8:10 PM, Pavel Begunkov wrote:
>> On 10/11/22 03:01, Jens Axboe wrote:
>>> On 10/10/22 7:10 PM, Pavel Begunkov wrote:
>>>> On 10/11/22 01:40, Dave Chinner wrote:
>>>> [...]
>>>>> I note that there are changes to the the io_uring IO path and write
>>>>> IO end accounting in the io_uring stack that was merged, and there
>>>>> was no doubt about the success/failure of the reproducer at each
>>>>> step. Hence I think the bisect is good, and the problem is someone
>>>>> in the io-uring changes.
>>>>>
>>>>> Jens, over to you.
>>>>>
>>>>> The reproducer - generic/068 - is 100% reliable here, io_uring is
>>>>> being exercised by fsstress in the background whilst the filesystem
>>>>> is being frozen and thawed repeatedly. Some path in the io-uring
>>>>> code has an unbalanced sb_start_write()/sb_end_write() pair by the
>>>>> look of it....
>>>>
>>>> A quick guess, it's probably
>>>>
>>>> b000145e99078 ("io_uring/rw: defer fsnotify calls to task context")
>>>>
>>>> ?From a quick look, it removes? kiocb_end_write() -> sb_end_write()
>>>> from kiocb_done(), which is a kind of buffered rw completion path.
>>>
>>> Yeah, I'll take a look.
>>> Didn't get the original email, only Pavel's reply?
>>
>> Forwarded.
>
> Looks like the email did get delivered, it just ended up in the
> fsdevel inbox.
Nope, it was marked as spam by gmail...
>> Not tested, but should be sth like below. Apart of obvious cases
>> like __io_complete_rw_common() we should also keep in mind
>> when we don't complete the request but ask for reissue with
>> REQ_F_REISSUE, that's for the first hunk
>
> Can we move this into a helper?
Something like this? Not super happy with it, but...
diff --git a/io_uring/rw.c b/io_uring/rw.c
index 453e0ae92160..1c8d00f9af9f 100644
--- a/io_uring/rw.c
+++ b/io_uring/rw.c
@@ -234,11 +234,32 @@ static void kiocb_end_write(struct io_kiocb *req)
}
}
+/*
+ * Trigger the notifications after having done some IO, and finish the write
+ * accounting, if any.
+ */
+static void io_req_io_end(struct io_kiocb *req)
+{
+ struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
+
+ if (rw->kiocb.ki_flags & IOCB_WRITE) {
+ kiocb_end_write(req);
+ fsnotify_modify(req->file);
+ } else {
+ fsnotify_access(req->file);
+ }
+}
+
static bool __io_complete_rw_common(struct io_kiocb *req, long res)
{
if (unlikely(res != req->cqe.res)) {
if ((res == -EAGAIN || res == -EOPNOTSUPP) &&
io_rw_should_reissue(req)) {
+ /*
+ * Reissue will start accounting again, finish the
+ * current cycle.
+ */
+ io_req_io_end(req);
req->flags |= REQ_F_REISSUE | REQ_F_PARTIAL_IO;
return true;
}
@@ -264,15 +285,7 @@ static inline int io_fixup_rw_res(struct io_kiocb *req, long res)
static void io_req_rw_complete(struct io_kiocb *req, bool *locked)
{
- struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
-
- if (rw->kiocb.ki_flags & IOCB_WRITE) {
- kiocb_end_write(req);
- fsnotify_modify(req->file);
- } else {
- fsnotify_access(req->file);
- }
-
+ io_req_io_end(req);
io_req_task_complete(req, locked);
}
@@ -317,6 +330,7 @@ static int kiocb_done(struct io_kiocb *req, ssize_t ret,
req->file->f_pos = rw->kiocb.ki_pos;
if (ret >= 0 && (rw->kiocb.ki_complete == io_complete_rw)) {
if (!__io_complete_rw_common(req, ret)) {
+ io_req_io_end(req);
io_req_set_res(req, final_ret,
io_put_kbuf(req, issue_flags));
return IOU_OK;
--
Jens Axboe
