[dm-devel] [PATCH v2 4/4] dm: Start pr_preempt from the same starting path

[Mike Christie]

pr_preempt has a similar issue as reserve where for all the reservation
types except the All Registrants ones the preempt can create a
reservation. And a follow up reservation or release needs to go down the
same path the preempt did. This has the pr_preempt work like reserve
and release where we always start from the first path in the first
group.

This patch has been tested with windows failover clustering's validation
test and libiscsi's PGR tests to check for regressions. They both don't
have tests to verify this case, so I tested it manually.

Signed-off-by: Mike Christie <michael.christie at oracle.com>
---
 drivers/md/dm.c | 45 +++++++++++++++++++++++++++++++--------------
 1 file changed, 31 insertions(+), 14 deletions(-)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index c31f99c9d2b2..7f23dde45088 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -3046,6 +3046,7 @@ struct dm_pr {
 	u64	old_key;
 	u64	new_key;
 	u32	flags;
+	bool	abort;
 	bool	fail_early;
 	int	ret;
 	enum pr_type type;
@@ -3218,25 +3219,41 @@ static int dm_pr_release(struct block_device *bdev, u64 key, enum pr_type type)
 	return pr.ret;
 }
 
+static int __dm_pr_preempt(struct dm_target *ti, struct dm_dev *dev,
+			   sector_t start, sector_t len, void *data)
+{
+	struct dm_pr *pr = data;
+	const struct pr_ops *ops = dev->bdev->bd_disk->fops->pr_ops;
+
+	if (!ops || !ops->pr_preempt) {
+		pr->ret = -EOPNOTSUPP;
+		return -1;
+	}
+
+	pr->ret = ops->pr_preempt(dev->bdev, pr->old_key, pr->new_key, pr->type,
+				  pr->abort);
+	if (!pr->ret)
+		return -1;
+
+	return 0;
+}
+
 static int dm_pr_preempt(struct block_device *bdev, u64 old_key, u64 new_key,
 			 enum pr_type type, bool abort)
 {
-	struct mapped_device *md = bdev->bd_disk->private_data;
-	const struct pr_ops *ops;
-	int r, srcu_idx;
+	struct dm_pr pr = {
+		.new_key	= new_key,
+		.old_key	= old_key,
+		.type		= type,
+		.fail_early	= false,
+	};
+	int ret;
 
-	r = dm_prepare_ioctl(md, &srcu_idx, &bdev);
-	if (r < 0)
-		goto out;
+	ret = dm_call_pr(bdev, __dm_pr_preempt, &pr);
+	if (ret)
+		return ret;
 
-	ops = bdev->bd_disk->fops->pr_ops;
-	if (ops && ops->pr_preempt)
-		r = ops->pr_preempt(bdev, old_key, new_key, type, abort);
-	else
-		r = -EOPNOTSUPP;
-out:
-	dm_unprepare_ioctl(md, srcu_idx);
-	return r;
+	return pr.ret;
 }
 
 static int dm_pr_clear(struct block_device *bdev, u64 key)
-- 
2.25.1