zbd: Fix unexpected job termination by open zone search failure

Test case #46 in t/zbd/test-zbd-support fails when it is repeated
hundreds of times on null_blk zoned devices. The test case uses libaio
IO engine to run 8 random write jobs on 4 sequential write required
zones. When all of the 4 zones get almost full but still open for
in-flight writes, the helper function zbd_convert_to_open_zone() fails
to get an opened zone for next write. This results in unexpected job
termination.

To avoid the unexpected job termination, retry the steps in
zbd_convert_to_open_zone(). Before retry, call io_u_quiesce() to ensure
that the in-flight writes get completed.

To prevent infinite loop by the retry, retry only when any IOs are
in-flight or in-flight IOs get completed. To check in-flight IO count of
all jobs, add a new helper function any_io_in_flight().

Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Reviewed-by: Niklas Cassel <niklas.cassel@wdc.com>
Reviewed-by: Dmitry Fomichev <dmitry.fomichev@wdc.com>
Link: https://lore.kernel.org/r/20210930000236.4116945-1-shinichiro.kawasaki@wdc.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/zbd.c b/zbd.c
index 64415d2b322ef932ece8fc5e1cce124dec9150dc..c0b0b81cab81ea56e2fbec9e6aba3c7ecf23d90a 100644 (file)
--- a/zbd.c
+++ b/zbd.c
@@ -1204,6 +1204,19 @@ static uint32_t pick_random_zone_idx(const struct fio_file *f,
                f->io_size;
 }
 
+static bool any_io_in_flight(void)
+{
+       struct thread_data *td;
+       int i;
+
+       for_each_td(td, i) {
+               if (td->io_u_in_flight)
+                       return true;
+       }
+
+       return false;
+}
+
 /*
  * Modify the offset of an I/O unit that does not refer to an open zone such
  * that it refers to an open zone. Close an open zone and open a new zone if
@@ -1223,6 +1236,8 @@ static struct fio_zone_info *zbd_convert_to_open_zone(struct thread_data *td,
        uint32_t zone_idx, new_zone_idx;
        int i;
        bool wait_zone_close;
+       bool in_flight;
+       bool should_retry = true;
 
        assert(is_valid_offset(f, io_u->offset));
 
@@ -1337,6 +1352,7 @@ open_other_zone:
                io_u_quiesce(td);
        }
 
+retry:
        /* Zone 'z' is full, so try to open a new zone. */
        for (i = f->io_size / zbdi->zone_size; i > 0; i--) {
                zone_idx++;
@@ -1376,6 +1392,24 @@ open_other_zone:
                        goto out;
                pthread_mutex_lock(&zbdi->mutex);
        }
+
+       /*
+        * When any I/O is in-flight or when all I/Os in-flight get completed,
+        * the I/Os might have closed zones then retry the steps to open a zone.
+        * Before retry, call io_u_quiesce() to complete in-flight writes.
+        */
+       in_flight = any_io_in_flight();
+       if (in_flight || should_retry) {
+               dprint(FD_ZBD, "%s(%s): wait zone close and retry open zones\n",
+                      __func__, f->file_name);
+               pthread_mutex_unlock(&zbdi->mutex);
+               zone_unlock(z);
+               io_u_quiesce(td);
+               zone_lock(td, f, z);
+               should_retry = in_flight;
+               goto retry;
+       }
+
        pthread_mutex_unlock(&zbdi->mutex);
        zone_unlock(z);
        dprint(FD_ZBD, "%s(%s): did not open another zone\n", __func__,