dio_submit and dio_submit_pad may produce several bios. This makes
processing of REQ_FUA complicated because in order to preserve correctness
we have to TAG each bio with FUA flag which is suboptimal.
Obviously there is a room for optimization here: once all bios was acknowledged
by lower layer we may issue empty barrier aka ->issue_flush().
post_submit call back is the place where we all bios completed already.
b1:FUA, b2:FUA, b3:FUA => b1,b2,b3,wait_for_bios,bX:FLUSH
This allow us to remove all this REQ_FORCE_{FLUSH,FUA} crap and
Signed-off-by: Dmitry Monakhov <dmonak...@openvz.org>
---
drivers/block/ploop/io_direct.c | 48 +++++++++++++++++------------------------
include/linux/ploop/ploop.h | 2 ++
2 files changed, 22 insertions(+), 28 deletions(-)
diff --git a/drivers/block/ploop/io_direct.c b/drivers/block/ploop/io_direct.c
index 195d318..752a9c3e 100644
--- a/drivers/block/ploop/io_direct.c
+++ b/drivers/block/ploop/io_direct.c
@@ -82,31 +82,13 @@ 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 preflush = !!(rw & REQ_FLUSH);
+ int postflush = !!(rw & REQ_FUA);
int write = !!(rw & REQ_WRITE);
trace_submit(preq);
- preflush = !!(rw & REQ_FLUSH);
-
- if (test_and_clear_bit(PLOOP_REQ_FORCE_FLUSH, &preq->state))
- preflush = 1;
-
- if (test_and_clear_bit(PLOOP_REQ_FORCE_FUA, &preq->state))
- postfua = 1;
-
- if (!postfua && ploop_req_delay_fua_possible(rw, preq)) {
-
- /* Mark req that delayed flush required */
- set_bit(PLOOP_REQ_FORCE_FLUSH, &preq->state);
- } else if (rw & REQ_FUA) {
- postfua = 1;
- }
-
rw &= ~(REQ_FLUSH | REQ_FUA);
-
-
bio_list_init(&bl);
if (iblk == PLOOP_ZERO_INDEX)
@@ -237,13 +219,14 @@ flush_bio:
rw2 |= REQ_FLUSH;
preflush = 0;
}
- if (unlikely(postfua && !bl.head))
- rw2 |= REQ_FUA;
-
ploop_acc_ff_out(preq->plo, rw2 | b->bi_rw);
submit_bio(rw2, b);
}
-
+ /* TODO: minor optimization is possible for single bio case */
+ if (postflush) {
+ set_bit(PLOOP_REQ_DEL_FLUSH, &preq->state);
+ ploop_add_post_submit(io, preq);
+ }
ploop_complete_io_request(preq);
return;
@@ -523,9 +506,10 @@ dio_convert_extent(struct ploop_io *io, struct
ploop_request * preq)
(loff_t)sec << 9, clu_siz);
/* highly unlikely case: FUA coming to a block not provisioned yet */
- if (!err && force_sync)
+ if (!err && force_sync) {
+ clear_bit(PLOOP_REQ_DEL_FLUSH, &preq->state);
err = io->ops->sync(io);
-
+ }
if (!force_sync) {
spin_lock_irq(&plo->lock);
io->io_count++;
@@ -546,7 +530,12 @@ dio_post_submit(struct ploop_io *io, struct ploop_request
* preq)
if (test_and_clear_bit(PLOOP_REQ_DEL_CONV, &preq->state))
dio_convert_extent(io, preq);
+ if (test_and_clear_bit(PLOOP_REQ_DEL_FLUSH, &preq->state)) {
+ io->ops->issue_flush(io, preq);
+ return 1;
+ }
return 0;
+
}
/* Submit the whole cluster. If preq contains only partial data
@@ -562,7 +551,6 @@ dio_submit_pad(struct ploop_io *io, struct ploop_request *
preq,
sector_t sec, end_sec, nsec, start, end;
struct bio_list_walk bw;
int err;
-
bio_list_init(&bl);
/* sec..end_sec is the range which we are going to write */
@@ -694,7 +682,11 @@ flush_bio:
ploop_acc_ff_out(preq->plo, rw | b->bi_rw);
submit_bio(rw, b);
}
-
+ /* TODO: minor optimization is possible for single bio case */
+ if (preq->req_rw & REQ_FUA) {
+ set_bit(PLOOP_REQ_DEL_FLUSH, &preq->state);
+ ploop_add_post_submit(io, preq);
+ }
ploop_complete_io_request(preq);
return;
diff --git a/include/linux/ploop/ploop.h b/include/linux/ploop/ploop.h
index 4c52a40..5076f16 100644
--- a/include/linux/ploop/ploop.h
+++ b/include/linux/ploop/ploop.h
@@ -472,6 +472,7 @@ enum
PLOOP_REQ_PUSH_BACKUP, /* preq was ACKed by userspace push_backup */
PLOOP_REQ_ALLOW_READS, /* READs are allowed for given req_cluster */
PLOOP_REQ_DEL_CONV, /* post_submit: conversion required */
+ PLOOP_REQ_DEL_FLUSH, /* post_submit: REQ_FLUSH required */
PLOOP_REQ_FSYNC_DONE, /* fsync_thread() performed f_op->fsync() */
};
@@ -482,6 +483,7 @@ enum
#define PLOOP_REQ_ZERO_FL (1 << PLOOP_REQ_ZERO)
#define PLOOP_REQ_POST_SUBMIT_FL (1 << PLOOP_REQ_POST_SUBMIT)
#define PLOOP_REQ_DEL_CONV_FL (1 << PLOOP_REQ_DEL_CONV)
+#define PLOOP_REQ_DEL_FLUSH_FL (1 << PLOOP_REQ_DEL_FLUSH)
enum
{
--
1.8.3.1
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