[dm-devel] [PATCH 2/3] dm: Start pr_reserve from the same starting path

[Mike Christie]

When an app does a pr_reserve it will go to whatever path we happen to
be using at the time. This can result in errors where the app does a
second pr_reserve call and expects success but gets a failure becuase
the reserve is not done on the holder's path. This patch has us always
start trying to do reserves from the first path in the first group.

Signed-off-by: Mike Christie <michael.christie at oracle.com>
---
 drivers/md/dm.c | 46 ++++++++++++++++++++++++++++++++--------------
 1 file changed, 32 insertions(+), 14 deletions(-)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 67b46ae896b1..cdd1656b99d6 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -3048,6 +3048,7 @@ struct dm_pr {
 	u32	flags;
 	bool	fail_early;
 	int	ret;
+	enum pr_type type;
 };
 
 static int dm_call_pr(struct block_device *bdev, iterate_devices_callout_fn fn,
@@ -3139,25 +3140,42 @@ static int dm_pr_register(struct block_device *bdev, u64 old_key, u64 new_key,
 	return ret;
 }
 
+
+static int __dm_pr_reserve(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_reserve) {
+		pr->ret = -EOPNOTSUPP;
+		return -1;
+	}
+
+	pr->ret = ops->pr_reserve(dev->bdev, pr->old_key, pr->type, pr->flags);
+	if (!pr->ret)
+		return -1;
+
+	return 0;
+}
+
 static int dm_pr_reserve(struct block_device *bdev, u64 key, enum pr_type type,
 			 u32 flags)
 {
-	struct mapped_device *md = bdev->bd_disk->private_data;
-	const struct pr_ops *ops;
-	int r, srcu_idx;
+	struct dm_pr pr = {
+		.old_key	= key,
+		.flags		= flags,
+		.type		= type,
+		.fail_early	= false,
+		.ret		= 0,
+	};
+	int ret;
 
-	r = dm_prepare_ioctl(md, &srcu_idx, &bdev);
-	if (r < 0)
-		goto out;
+	ret = dm_call_pr(bdev, __dm_pr_reserve, &pr);
+	if (ret)
+		return ret;
 
-	ops = bdev->bd_disk->fops->pr_ops;
-	if (ops && ops->pr_reserve)
-		r = ops->pr_reserve(bdev, key, type, flags);
-	else
-		r = -EOPNOTSUPP;
-out:
-	dm_unprepare_ioctl(md, srcu_idx);
-	return r;
+	return pr.ret;
 }
 
 static int dm_pr_release(struct block_device *bdev, u64 key, enum pr_type type)
-- 
2.25.1