The commit is pushed to "branch-rh9-5.14.0-427.55.1.vz9.82.x-ovz" and will
appear at g...@bitbucket.org:openvz/vzkernel.git
after rh9-5.14.0-427.55.1.vz9.82.8
------>
commit 2ca8fae2ae23d814b347eef8b43630e4e4e11aa3
Author: Andrey Zhadchenko <andrey.zhadche...@virtuozzo.com>
Date: Wed Jul 16 12:37:52 2025 +0300
dm-ploop: add inflight metadata writeback counter
and use it during ploop_suspend_submitting_pios() to wait for all
writeback to flush
https://virtuozzo.atlassian.net/browse/VSTOR-108540
Signed-off-by: Andrey Zhadchenko <andrey.zhadche...@virtuozzo.com>
Reviewed-by: Pavel Tikhomirov <ptikhomi...@virtuozzo.com>
Feature: dm-ploop: ploop target driver
======
Patchset description:
dm-ploop: improve pio submission suspension
Recently we encountered EBUSY errors while trying to resize ploop
devices under load. This mostly happens because we are not waiting
in-progess IO correctly:
- initial pio is removed from inflight even if its split pios are
still running
- there is no wait for metadata writeback
This patchset fixes that by moving inflight decrease later and
introducing new counter for inflight metadata writeback.
Note that for dm-qcow2 patches are not needed: it does not have
delayed metadata writeback and inflight counters are decreased
correctly at the time of endio_cb.
https://virtuozzo.atlassian.net/browse/VSTOR-108540
---
drivers/md/dm-ploop-cmd.c | 6 ++++++
drivers/md/dm-ploop-map.c | 5 +++++
drivers/md/dm-ploop-target.c | 2 ++
drivers/md/dm-ploop.h | 3 +++
4 files changed, 16 insertions(+)
diff --git a/drivers/md/dm-ploop-cmd.c b/drivers/md/dm-ploop-cmd.c
index 85bb69714ca86..2043162164be1 100644
--- a/drivers/md/dm-ploop-cmd.c
+++ b/drivers/md/dm-ploop-cmd.c
@@ -151,6 +151,12 @@ static int ploop_suspend_submitting_pios(struct ploop
*ploop)
spin_unlock_irq(&ploop->deferred_lock);
ret = ploop_inflight_bios_ref_switch(ploop, true);
+ if (ret)
+ goto out;
+
+ ret = wait_event_interruptible(ploop->inflight_md_wq,
+ !atomic_read(&ploop->inflight_md));
+out:
if (ret)
ploop_resume_submitting_pios(ploop);
return ret;
diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index 40eca0a6f83f6..f717967a8bde1 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -936,6 +936,8 @@ static void ploop_put_piwb(struct ploop_index_wb *piwb)
* zero keeps it as is
*/
+ if (atomic_dec_and_test(&piwb->ploop->inflight_md))
+ wake_up_interruptible(&piwb->ploop->inflight_md_wq);
ploop_free_piwb(piwb);
}
}
@@ -1094,6 +1096,7 @@ static int ploop_prepare_bat_update(struct ploop *ploop,
struct md_page *md,
kunmap_local(to);
piwb->type = type;
+ atomic_inc(&ploop->inflight_md);
return 0;
err:
ploop_free_piwb(piwb);
@@ -1113,6 +1116,8 @@ void ploop_break_bat_update(struct ploop *ploop, struct
md_page *md,
spin_unlock(&md->md_lock);
spin_unlock_irqrestore(&ploop->bat_lock, flags);
+ if (atomic_dec_and_test(&ploop->inflight_md))
+ wake_up_interruptible(&ploop->inflight_md_wq);
ploop_free_piwb(piwb);
}
diff --git a/drivers/md/dm-ploop-target.c b/drivers/md/dm-ploop-target.c
index af0658a455ced..6d1881ea3828d 100644
--- a/drivers/md/dm-ploop-target.c
+++ b/drivers/md/dm-ploop-target.c
@@ -566,8 +566,10 @@ static int ploop_ctr(struct dm_target *ti, unsigned int
argc, char **argv)
init_waitqueue_head(&ploop->dispatcher_wq_data);
init_waitqueue_head(&ploop->dispatcher_wq_fsync);
init_waitqueue_head(&ploop->dispatcher_wq_prealloc);
+ init_waitqueue_head(&ploop->inflight_md_wq);
ploop->prealloc_size = 0;
ploop->prealloc_in_progress = 0;
+ atomic_set(&ploop->inflight_md, 0);
ploop->kt_worker = ploop_worker_create(ploop, ploop_worker, "d", 0);
if (!ploop->kt_worker)
diff --git a/drivers/md/dm-ploop.h b/drivers/md/dm-ploop.h
index b66672eef5ee9..5a88664feb687 100644
--- a/drivers/md/dm-ploop.h
+++ b/drivers/md/dm-ploop.h
@@ -267,6 +267,9 @@ struct ploop {
loff_t prealloc_size;
loff_t prealloc_in_progress;
struct wait_queue_head dispatcher_wq_prealloc;
+
+ atomic_t inflight_md;
+ struct wait_queue_head inflight_md_wq;
};
#define ploop_blk_queue(p) ((p)->ti->table->md->queue)
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