On 06/24/2016 07:42 AM, Dmitry Monakhov wrote:
Maxim Patlasov <mpatla...@virtuozzo.com> writes:
After commit c2247f3745 fixing barriers for ordinary
requests and previous patch fixing delay_fua,
that legacy code in dio_submit processing
(preq->req_rw & REQ_FLUSH) by setting REQ_FLUSH in
the first outgoing bio must die: it is incorrect
anyway (we don't wait for completion of the first
bio before sending others).
Wow. This is so true. BTW: Reasonable way to handle FLUSH
is to queue such preq to preflush_queue similar to fsync_queue for
fsync_thread infrastructure
This would add another WAIT. Sometimes it may be beneficial (many
incoming bio-s marked as REQ_FLUSH), sometimes not (only one bio with
REQ_FLUSH -- so we'll mark only one of outgoing bio-s with REQ_FLUSH).
Who knows how often we have more than one REQ_FLUSH in queue...
Signed-off-by: Maxim Patlasov <mpatla...@virtuozzo.com>
---
drivers/block/ploop/io_direct.c | 7 -------
1 file changed, 7 deletions(-)
diff --git a/drivers/block/ploop/io_direct.c b/drivers/block/ploop/io_direct.c
index 1ea2008..ee3cd5c 100644
--- a/drivers/block/ploop/io_direct.c
+++ b/drivers/block/ploop/io_direct.c
@@ -89,15 +89,12 @@ dio_submit(struct ploop_io *io, struct ploop_request * preq,
sector_t sec, nsec;
int err;
struct bio_list_walk bw;
- int preflush;
int postfua = 0;
int write = !!(rw & REQ_WRITE);
int delayed_fua = 0;
trace_submit(preq);
- preflush = !!(rw & REQ_FLUSH);
-
if (test_and_clear_bit(PLOOP_REQ_FORCE_FUA, &preq->state))
postfua = 1;
@@ -236,10 +233,6 @@ flush_bio:
b->bi_private = preq;
b->bi_end_io = dio_endio_async;
- if (unlikely(preflush)) {
- rw2 |= REQ_FLUSH;
- preflush = 0;
- }
if (unlikely(postfua && !bl.head))
rw2 |= REQ_FUA;
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