[Devel] [PATCH rh7] ploop: pio_nfs does not require PLOOP_REQ_ISSUE_FLUSH

[Maxim Patlasov]

The flag was introduced for local case: if we modify local
block-device directly, bypassing ext4, we cannot rely on
fsync() and must flush the device explicitly. It is not the
case for pio_nfs, so it's not necessary to set
PLOOP_REQ_ISSUE_FLUSH.

The patch is important because pio_nfs doesn't provide
issue_flush method.

Signed-off-by: Maxim Patlasov <mpatlasov at virtuozzo.com>
---
 drivers/block/ploop/map.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/block/ploop/map.c b/drivers/block/ploop/map.c
index 715dc15..154a897 100644
--- a/drivers/block/ploop/map.c
+++ b/drivers/block/ploop/map.c
@@ -1113,9 +1113,11 @@ static void map_wb_complete_post_process(struct ploop_map *map,
 	 * (see dio_submit()). So fsync of EXT4 image doesnt help us.
 	 * We need to force sync of nullified blocks.
 	 */
-	preq->eng_io = &top_delta->io;
+	if (top_delta->io.ops->issue_flush) {
+		preq->eng_io = &top_delta->io;
+		set_bit(PLOOP_REQ_ISSUE_FLUSH, &preq->state);
+	}
 	BUG_ON(test_bit(PLOOP_REQ_POST_SUBMIT, &preq->state));
-	set_bit(PLOOP_REQ_ISSUE_FLUSH, &preq->state);
 	top_delta->io.ops->submit(&top_delta->io, preq, preq->req_rw,
 				  &sbl, preq->iblock, 1<<plo->cluster_log);
 }