The last step of processing of RELOC_A request is
nullifying BAT block. We smartly noticed, that flush
needed after that, but fsync is not enough:
> /*
> * Lately we think we does sync of nullified blocks at format
> * driver by image fsync before header update.
> * But we write this data directly into underlying device
> * bypassing EXT4 by usage of extent map tree
> * (see dio_submit()). So fsync of EXT4 image doesnt help us.
> * We need to force sync of nullified blocks.
> */
> set_bit(PLOOP_REQ_FORCE_FUA, &preq->state);
> top_delta->io.ops->submit(&top_delta->io, preq, preq->req_rw,
> &sbl, preq->iblock, 1<<plo->cluster_log);
Unfortunately, the way how we handle FORCE_FUA in dio_submit
(sending last bio with REQ_FUA bit set) is not safe: firstly because
we decided that ploop shouldn't strongly rely on the assumption of
equivalence of REQ_FUA and post-FLUSH; and secondly because dio_submit
cannot ensure that that last bio marked as REQ_FUA won't be actually
processed before others.
To fix this problem the patch makes explicit ->issue_flush to flush
nullified block.
Signed-off-by: Maxim Patlasov <mpatla...@virtuozzo.com>
---
drivers/block/ploop/dev.c | 11 ++++++++++-
drivers/block/ploop/io_direct.c | 3 ++-
drivers/block/ploop/map.c | 4 +++-
include/linux/ploop/ploop.h | 1 +
4 files changed, 16 insertions(+), 3 deletions(-)
diff --git a/drivers/block/ploop/dev.c b/drivers/block/ploop/dev.c
index 557ddba..2b60dfa 100644
--- a/drivers/block/ploop/dev.c
+++ b/drivers/block/ploop/dev.c
@@ -1305,6 +1305,8 @@ static void ploop_complete_request(struct ploop_request *
preq)
}
preq->bl.tail = NULL;
+ WARN_ON(!preq->error && test_bit(PLOOP_REQ_ISSUE_FLUSH, &preq->state));
+
if (test_bit(PLOOP_REQ_RELOC_A, &preq->state) ||
test_bit(PLOOP_REQ_RELOC_S, &preq->state)) {
if (preq->error)
@@ -2429,6 +2431,13 @@ static void ploop_req_state_process(struct ploop_request
* preq)
preq->eng_io = NULL;
}
+ if (test_bit(PLOOP_REQ_ISSUE_FLUSH, &preq->state)) {
+ preq->eng_io->ops->issue_flush(preq->eng_io, preq);
+ clear_bit(PLOOP_REQ_ISSUE_FLUSH, &preq->state);
+ preq->eng_io = NULL;
+ goto out;
+ }
+
restart:
BUG_ON(test_bit(PLOOP_REQ_POST_SUBMIT, &preq->state));
__TRACE("ST %p %u %lu\n", preq, preq->req_cluster, preq->eng_state);
@@ -2705,7 +2714,7 @@ restart:
default:
BUG();
}
-
+out:
if (release_ioc) {
struct io_context * ioc = current->io_context;
current->io_context = saved_ioc;
diff --git a/drivers/block/ploop/io_direct.c b/drivers/block/ploop/io_direct.c
index 94936c7..c4d0f63 100644
--- a/drivers/block/ploop/io_direct.c
+++ b/drivers/block/ploop/io_direct.c
@@ -413,6 +413,7 @@ try_again:
preq->iblock = iblk;
preq->eng_io = io;
+ BUG_ON(test_bit(PLOOP_REQ_ISSUE_FLUSH, &preq->state));
set_bit(PLOOP_REQ_POST_SUBMIT, &preq->state);
dio_submit_pad(io, preq, sbl, size, em);
err = 0;
@@ -1819,7 +1820,7 @@ static void dio_issue_flush(struct ploop_io * io, struct
ploop_request *preq)
atomic_inc(&preq->io_count);
ploop_acc_ff_out(io->plo, preq->req_rw | bio->bi_rw);
- submit_bio(preq->req_rw, bio);
+ submit_bio(WRITE_FLUSH, bio);
ploop_complete_io_request(preq);
}
diff --git a/drivers/block/ploop/map.c b/drivers/block/ploop/map.c
index f87fb08..915a216 100644
--- a/drivers/block/ploop/map.c
+++ b/drivers/block/ploop/map.c
@@ -1077,7 +1077,9 @@ 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.
*/
- set_bit(PLOOP_REQ_FORCE_FUA, &preq->state);
+ preq->eng_io = &top_delta->io;
+ 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);
}
diff --git a/include/linux/ploop/ploop.h b/include/linux/ploop/ploop.h
index af222f1..920daf7 100644
--- a/include/linux/ploop/ploop.h
+++ b/include/linux/ploop/ploop.h
@@ -479,6 +479,7 @@ enum
PLOOP_REQ_POST_SUBMIT, /* preq needs post_submit processing */
PLOOP_REQ_PUSH_BACKUP, /* preq was ACKed by userspace push_backup */
PLOOP_REQ_FSYNC_DONE, /* fsync_thread() performed f_op->fsync() */
+ PLOOP_REQ_ISSUE_FLUSH, /* preq needs ->issue_flush before completing */
};
#define PLOOP_REQ_MERGE_FL (1 << PLOOP_REQ_MERGE)
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