From: Hans Holmberg <hans.holmberg@cnexlabs.com>
Date: Fri, 5 Jan 2018 14:16:11 +0100
Subject: [PATCH] lightnvm: pblk: prevent premature sync point resets
Git-commit: b36bbf9d4f731269b4fe88e1060af1e8c28b7972
Patch-mainline: v4.16-rc1
References: bsc#1104967,FATE#325924
MIME-Version: 1.0
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Unless we protect flush pointer updates with a lock, we risk
resetting new flush points before we've synced all sectors
up to that point.

This patch protects new flush points with the same spin lock
that is being held when advancing the sync pointer and
resetting completed flush points.

Signed-off-by: Hans Holmberg <hans.holmberg@cnexlabs.com>
Signed-off-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Hannes Reinecke <hare@suse.com>
---
 drivers/lightnvm/pblk-rb.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/lightnvm/pblk-rb.c b/drivers/lightnvm/pblk-rb.c
index 672ef8c47892..ec8fc314646b 100644
--- a/drivers/lightnvm/pblk-rb.c
+++ b/drivers/lightnvm/pblk-rb.c
@@ -367,17 +367,17 @@ static int pblk_rb_flush_point_set(struct pblk_rb *rb, struct bio *bio,
 	flush_point = (pos == 0) ? (rb->nr_entries - 1) : (pos - 1);
 	entry = &rb->entries[flush_point];
 
+	pblk_rb_sync_init(rb, NULL);
+
 	/* Protect flush points */
 	smp_store_release(&rb->flush_point, flush_point);
 
-	if (!bio)
-		return 0;
+	if (bio)
+		bio_list_add(&entry->w_ctx.bios, bio);
 
-	spin_lock_irq(&rb->s_lock);
-	bio_list_add(&entry->w_ctx.bios, bio);
-	spin_unlock_irq(&rb->s_lock);
+	pblk_rb_sync_end(rb, NULL);
 
-	return 1;
+	return bio ? 1 : 0;
 }
 
 static int __pblk_rb_may_write(struct pblk_rb *rb, unsigned int nr_entries,
-- 
2.12.3