[Devel] [PATCH RHEL8 COMMIT] ploop: Add flush_worker

[Konstantin Khorenko]

The commit is pushed to "branch-rh8-4.18.0-240.1.1.vz8.5.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh8-4.18.0-240.1.1.vz8.5.30
------>
commit cb59663f6125e93e8f484b5d7d5e75ea6f132ac4
Author: Kirill Tkhai <ktkhai at virtuozzo.com>
Date:   Mon May 17 19:04:38 2021 +0300

    ploop: Add flush_worker
    
    This is preparation for flushing in separate thread.
    
    Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
    
    =====================
    Patchset description:
    
    dm-ploop: Kill loop
    
    Intermediate patches can't be base for bisect.
    
    In scope of https://jira.sw.ru/browse/PSBM-123654
    
    Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
---
 drivers/md/dm-ploop-map.c    | 28 ++++++++++++++++++++++++++--
 drivers/md/dm-ploop-target.c |  2 ++
 drivers/md/dm-ploop.h        |  3 +++
 3 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index dd209f2a0a8c..6f1b602117c8 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -1590,6 +1590,23 @@ void do_ploop_work(struct work_struct *ws)
 	check_services_timeout(ploop);
 }
 
+void do_ploop_fsync_work(struct work_struct *ws)
+{
+	struct ploop *ploop = container_of(ws, struct ploop, fsync_worker);
+	struct bio_list flush_bios = BIO_EMPTY_LIST;
+	struct bio *bio;
+
+	spin_lock_irq(&ploop->deferred_lock);
+	bio_list_merge(&flush_bios, &ploop->flush_bios);
+	bio_list_init(&ploop->flush_bios);
+	spin_unlock_irq(&ploop->deferred_lock);
+
+	/* FIXME: issue flush */
+
+	while ((bio = bio_list_pop(&flush_bios)) != NULL)
+		bio_endio(bio);
+}
+
 /*
  * ploop_map() tries to map bio to origins or delays it.
  * It never modifies ploop->bat_entries and other cached
@@ -1599,6 +1616,7 @@ int ploop_map(struct dm_target *ti, struct bio *bio)
 {
 	struct ploop *ploop = ti->private;
 	unsigned int cluster;
+	unsigned long flags;
 
 	ploop_init_end_io(ploop, bio);
 
@@ -1612,9 +1630,15 @@ int ploop_map(struct dm_target *ti, struct bio *bio)
 		return DM_MAPIO_SUBMITTED;
 	}
 
-	remap_to_origin(ploop, bio);
+	if (WARN_ON_ONCE(!op_is_flush(bio->bi_opf)))
+		return DM_MAPIO_KILL;
 
-	return DM_MAPIO_REMAPPED;
+	spin_lock_irqsave(&ploop->deferred_lock, flags);
+	bio_list_add(&ploop->flush_bios, bio);
+	spin_unlock_irqrestore(&ploop->deferred_lock, flags);
+	queue_work(ploop->wq, &ploop->fsync_worker);
+
+	return DM_MAPIO_SUBMITTED;
 }
 
 int ploop_endio(struct dm_target *ti, struct bio *bio, blk_status_t *err)
diff --git a/drivers/md/dm-ploop-target.c b/drivers/md/dm-ploop-target.c
index 8a2a5312195e..f8d471581ac0 100644
--- a/drivers/md/dm-ploop-target.c
+++ b/drivers/md/dm-ploop-target.c
@@ -206,6 +206,7 @@ static int ploop_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	spin_lock_init(&ploop->pb_lock);
 
 	bio_list_init(&ploop->deferred_bios);
+	bio_list_init(&ploop->flush_bios);
 	bio_list_init(&ploop->discard_bios);
 	INIT_LIST_HEAD(&ploop->cluster_lk_list);
 	bio_list_init(&ploop->delta_cow_action_list);
@@ -215,6 +216,7 @@ static int ploop_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	ploop->inflight_bios_rbtree = RB_ROOT;
 
 	INIT_WORK(&ploop->worker, do_ploop_work);
+	INIT_WORK(&ploop->fsync_worker, do_ploop_fsync_work);
 	init_completion(&ploop->inflight_bios_ref_comp);
 
 	for (i = 0; i < 2; i++) {
diff --git a/drivers/md/dm-ploop.h b/drivers/md/dm-ploop.h
index 0eb313d4c412..1dfe3dc7df60 100644
--- a/drivers/md/dm-ploop.h
+++ b/drivers/md/dm-ploop.h
@@ -194,6 +194,7 @@ struct ploop {
 
 	struct workqueue_struct *wq;
 	struct work_struct worker;
+	struct work_struct fsync_worker;
 
 	struct completion inflight_bios_ref_comp;
 	struct percpu_ref inflight_bios_ref[2];
@@ -202,6 +203,7 @@ struct ploop {
 
 	spinlock_t deferred_lock;
 	struct bio_list deferred_bios;
+	struct bio_list flush_bios;
 	struct bio_list discard_bios;
 
 	struct rw_semaphore ctl_rwsem;
@@ -474,6 +476,7 @@ extern bool try_update_bat_entry(struct ploop *ploop, unsigned int cluster,
 extern int ploop_add_delta(struct ploop *ploop, u32 level, struct file *file, bool is_raw);
 extern void defer_bios(struct ploop *ploop, struct bio *bio, struct bio_list *bio_list);
 extern void do_ploop_work(struct work_struct *ws);
+extern void do_ploop_fsync_work(struct work_struct *ws);
 extern void process_deferred_cmd(struct ploop *ploop,
 			struct ploop_index_wb *piwb);
 extern int ploop_map(struct dm_target *ti, struct bio *bio);