block: factor out a part_devt helper

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

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20210525061301.2242282-8-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/genhd.c b/block/genhd.c
index 38d136a19484fa84cf622cbfe86621b45779c237..3f7b1c92c7f3c779383c8a9105c5f42c5c66f36c 100644 (file)
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1227,6 +1227,19 @@ 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);
@@ -1236,7 +1249,6 @@ 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;
@@ -1247,13 +1259,10 @@ 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 47d4605c0e7e91dbc37f4b11b70d1423c6e83576..64a8431202b79b1a4e6843ab5e961a4653f8f58a 100644 (file)
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -333,6 +333,7 @@ static inline void bd_unlink_disk_holder(struct block_device *bdev,
 }
 #endif /* CONFIG_SYSFS */
 
+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 a78e44ee6adb8d12b22d83b351ed8bac50082cdd..74aede860de7396f157257491b00f01a03a1bdfb 100644 (file)
--- 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;
        }