[Devel] [PATCH rh7 2/9] ploop: minor rework of ploop_req_delay_fua_possible

[Maxim Patlasov]

No functional changes. The patch simplifies ploop_req_delay_fua_possible
to make it more suitable for next patch. As was recently discussed,
"eng_state == E_DATA_WBI" is lesser prone to errors than
"eng_state != E_COMPLETE".

Note, how the patch makes a bug in kaio_complete_io_state() obvious:
if !(preq->req_rw & REQ_FUA), it must not matter what
ploop_req_delay_fua_possible() returns! I.e., eng_state==E_COMPLETE is
not sufficient ground for post_fsync=1 if no REQ_FUA set.

Signed-off-by: Maxim Patlasov <mpatlasov at virtuozzo.com>
---
 drivers/block/ploop/io_direct.c |    2 +-
 drivers/block/ploop/io_kaio.c   |    3 +--
 include/linux/ploop/ploop.h     |   15 ++-------------
 3 files changed, 4 insertions(+), 16 deletions(-)

diff --git a/drivers/block/ploop/io_direct.c b/drivers/block/ploop/io_direct.c
index 3acae79..0907540 100644
--- a/drivers/block/ploop/io_direct.c
+++ b/drivers/block/ploop/io_direct.c
@@ -103,7 +103,7 @@ dio_submit(struct ploop_io *io, struct ploop_request * preq,
 	if (test_and_clear_bit(PLOOP_REQ_FORCE_FUA, &preq->state))
 		postfua = 1;
 
-	if (!postfua && ploop_req_delay_fua_possible(rw, preq)) {
+	if (!postfua && ploop_req_delay_fua_possible(preq) && (rw & REQ_FUA)) {
 
 		/* Mark req that delayed flush required */
 		set_bit(PLOOP_REQ_FORCE_FLUSH, &preq->state);
diff --git a/drivers/block/ploop/io_kaio.c b/drivers/block/ploop/io_kaio.c
index 81da1c5..69df456 100644
--- a/drivers/block/ploop/io_kaio.c
+++ b/drivers/block/ploop/io_kaio.c
@@ -84,8 +84,7 @@ static void kaio_complete_io_state(struct ploop_request * preq)
 		post_fsync = 1;
 
 	if (!post_fsync &&
-	    !ploop_req_delay_fua_possible(preq->req_rw, preq) &&
-	    (preq->req_rw & REQ_FUA))
+	    !(ploop_req_delay_fua_possible(preq) && (preq->req_rw & REQ_FUA)))
 		post_fsync = 1;
 
 	preq->req_rw &= ~REQ_FUA;
diff --git a/include/linux/ploop/ploop.h b/include/linux/ploop/ploop.h
index 3441e7e..e1d8686 100644
--- a/include/linux/ploop/ploop.h
+++ b/include/linux/ploop/ploop.h
@@ -613,20 +613,9 @@ void ploop_preq_drop(struct ploop_device * plo, struct list_head *drop_list,
 		      int keep_locked);
 
 
-static inline int ploop_req_delay_fua_possible(unsigned long rw,
-       struct ploop_request *preq)
+static inline int ploop_req_delay_fua_possible(struct ploop_request *preq)
 {
-	int delay_fua = 0;
-
-	/* In case of eng_state != COMPLETE, we'll do FUA in
-	 * ploop_index_update(). Otherwise, we should post
-	 * fua.
-	 */
-	if (rw & REQ_FUA) {
-		if (preq->eng_state != PLOOP_E_COMPLETE)
-			delay_fua = 1;
-	}
-	return delay_fua;
+	return preq->eng_state == PLOOP_E_DATA_WBI;
 }
 
 static inline void ploop_req_set_error(struct ploop_request * preq, int err)