[PATCH 7/8] block: factor out a part_devt helper

[Christoph Hellwig <hch@xxxxxx>]

Add a helper to find the dev_t for a disk + partno tuple.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 block/genhd.c         | 25 +++++++++++++++++--------
 include/linux/genhd.h |  1 +
 init/do_mounts.c      | 10 ++--------
 3 files changed, 20 insertions(+), 16 deletions(-)

diff --git a/block/genhd.c b/block/genhd.c
index 8b88e99f6675..14fd777811fe 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1251,6 +1251,19 @@ static int __init proc_genhd_init(void)
 module_init(proc_genhd_init);
 #endif /* CONFIG_PROC_FS */
 
+dev_t part_devt(struct gendisk *disk, u8 partno)
+{
+	struct block_device *part = bdget_disk(disk, partno);
+	dev_t devt = 0;
+
+	if (part) {
+		devt = part->bd_dev;
+		bdput(part);
+	}
+
+	return devt;
+}
+
 dev_t blk_lookup_devt(const char *name, int partno)
 {
 	dev_t devt = MKDEV(0, 0);
@@ -1260,7 +1273,6 @@ dev_t blk_lookup_devt(const char *name, int partno)
 	class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
 	while ((dev = class_dev_iter_next(&iter))) {
 		struct gendisk *disk = dev_to_disk(dev);
-		struct block_device *part;
 
 		if (strcmp(dev_name(dev), name))
 			continue;
@@ -1271,13 +1283,10 @@ dev_t blk_lookup_devt(const char *name, int partno)
 			 */
 			devt = MKDEV(MAJOR(dev->devt),
 				     MINOR(dev->devt) + partno);
-			break;
-		}
-		part = bdget_disk(disk, partno);
-		if (part) {
-			devt = part->bd_dev;
-			bdput(part);
-			break;
+		} else {
+			devt = part_devt(disk, partno);
+			if (devt)
+				break;
 		}
 	}
 	class_dev_iter_exit(&iter);
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 74fd28ddac70..4c4d903caa09 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -312,6 +312,7 @@ static inline void bd_unlink_disk_holder(struct block_device *bdev,
 
 extern struct rw_semaphore bdev_lookup_sem;
 
+dev_t part_devt(struct gendisk *disk, u8 partno);
 dev_t blk_lookup_devt(const char *name, int partno);
 void blk_request_module(dev_t devt);
 #ifdef CONFIG_BLOCK
diff --git a/init/do_mounts.c b/init/do_mounts.c
index a78e44ee6adb..74aede860de7 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -133,14 +133,8 @@ static dev_t devt_from_partuuid(const char *uuid_str)
 		 * Attempt to find the requested partition by adding an offset
 		 * to the partition number found by UUID.
 		 */
-		struct block_device *part;
-
-		part = bdget_disk(dev_to_disk(dev),
-				  dev_to_bdev(dev)->bd_partno + offset);
-		if (part) {
-			devt = part->bd_dev;
-			bdput(part);
-		}
+		devt = part_devt(dev_to_disk(dev),
+				 dev_to_bdev(dev)->bd_partno + offset);
 	} else {
 		devt = dev->devt;
 	}
-- 
2.30.2