[Devel] [RH7 PATCH] ploop: reloc vs extent_conversion race fix

[Dmitry Monakhov]

We have fixed most relocation bugs during fixing https://jira.sw.ru/browse/PSBM-47107

Currently reloc_a looks like follows:

 1->read_data_from_old_post
 2->write_to_new_pos
    ->sumbit_alloc
      ->submit_pad
  ->post_submit->convert_unwritten
 3->update_index ->write_page with FLUSH|FUA
 4->nullify_old_pos
 5->issue_flush

But on step 3 extent coversion is not yet stable because belongs to uncommitted
transaction. We MUST call ->fsync inside ->post_sumit as we do for REQ_FUA
requests. Let's tag relocatoin requests as FUA from very beginning in order to
assert sync semantics.

https://jira.sw.ru/browse/PSBM-49143
Signed-off-by: Dmitry Monakhov <dmonakhov at openvz.org>
---
 drivers/block/ploop/dev.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/block/ploop/dev.c b/drivers/block/ploop/dev.c
index 40768b6..e5f010b 100644
--- a/drivers/block/ploop/dev.c
+++ b/drivers/block/ploop/dev.c
@@ -4097,7 +4097,7 @@ static void ploop_relocate(struct ploop_device * plo)
 	preq->bl.tail = preq->bl.head = NULL;
 	preq->req_cluster = 0;
 	preq->req_size = 0;
-	preq->req_rw = WRITE_SYNC;
+	preq->req_rw = WRITE_SYNC|REQ_FUA;
 	preq->eng_state = PLOOP_E_ENTRY;
 	preq->state = (1 << PLOOP_REQ_SYNC) | (1 << PLOOP_REQ_RELOC_A);
 	preq->error = 0;
@@ -4401,7 +4401,7 @@ static void ploop_relocblks_process(struct ploop_device *plo)
 		preq->bl.tail = preq->bl.head = NULL;
 		preq->req_cluster = ~0U; /* uninitialized */
 		preq->req_size = 0;
-		preq->req_rw = WRITE_SYNC;
+		preq->req_rw = WRITE_SYNC|REQ_FUA;
 		preq->eng_state = PLOOP_E_ENTRY;
 		preq->state = (1 << PLOOP_REQ_SYNC) | (1 << PLOOP_REQ_RELOC_S);
 		preq->error = 0;
-- 
1.8.3.1