[PATCH 1/2] dm: factor out helper function from dm_get_device

[Benjamin Marzinski <bmarzins@xxxxxxxxxx>]

Factor out a helper function, dm_devt_from_path(), from dm_get_device()
for use in dm targets.

Signed-off-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx>
---
 drivers/md/dm-table.c         | 33 ++++++++++++++++++++++++---------
 include/linux/device-mapper.h |  5 +++++
 2 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index d124e37dfb00..41b58e0c6876 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -329,23 +329,15 @@ static int upgrade_mode(struct dm_dev_internal *dd, blk_mode_t new_mode,
 }
 
 /*
- * Add a device to the list, or just increment the usage count if
- * it's already present.
- *
  * Note: the __ref annotation is because this function can call the __init
  * marked early_lookup_bdev when called during early boot code from dm-init.c.
  */
-int __ref dm_get_device(struct dm_target *ti, const char *path, blk_mode_t mode,
-		  struct dm_dev **result)
+int __ref dm_devt_from_path(const char *path, dev_t *dev_p)
 {
 	int r;
 	dev_t dev;
 	unsigned int major, minor;
 	char dummy;
-	struct dm_dev_internal *dd;
-	struct dm_table *t = ti->table;
-
-	BUG_ON(!t);
 
 	if (sscanf(path, "%u:%u%c", &major, &minor, &dummy) == 2) {
 		/* Extract the major/minor numbers */
@@ -361,6 +353,29 @@ int __ref dm_get_device(struct dm_target *ti, const char *path, blk_mode_t mode,
 		if (r)
 			return r;
 	}
+	*dev_p = dev;
+	return 0;
+}
+EXPORT_SYMBOL(dm_devt_from_path);
+
+/*
+ * Add a device to the list, or just increment the usage count if
+ * it's already present.
+ */
+int dm_get_device(struct dm_target *ti, const char *path, blk_mode_t mode,
+		  struct dm_dev **result)
+{
+	int r;
+	dev_t dev;
+	struct dm_dev_internal *dd;
+	struct dm_table *t = ti->table;
+
+	BUG_ON(!t);
+
+	r = dm_devt_from_path(path, &dev);
+	if (r)
+		return r;
+
 	if (dev == disk_devt(t->md->disk))
 		return -EINVAL;
 
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 82b2195efaca..b4c7c4fa2de6 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -179,6 +179,11 @@ int dm_get_device(struct dm_target *ti, const char *path, blk_mode_t mode,
 		  struct dm_dev **result);
 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
 
+/*
+ * Helper function for getting devices
+ */
+int dm_devt_from_path(const char *path, dev_t *dev_p);
+
 /*
  * Information about a target type
  */
-- 
2.45.0