[PATCH] btrfs: kobject_uevent should use bd_part instead of bd_disk

[Anand Jain <anand.jain@oracle.com>]

From: Anand Jain <Anand.Jain@oracle.com>

reproducer 1:
 mkfs.btrfs -L test /dev/sdg1
 mount LABEL=test /btrfs
 btrfs dev add /dev/sdg2 /btrfs
 btrfs dev del /dev/sdg1 /btrfs
 umount /btrfs
 mount LABEL=test /btrfs
   mount: special device LABEL-test1 does not exist

 It does not reproduce this problem when whole disk is used.
 And when newer kernel is used not sure what change in udev
 is doing the trick. But in any case reproducer2 below is
 more compelling.

reproducer 2:
 btrfs dev del /dev/sdh2 /btrfs
 ls -l /dev/sdh1 /dev/sdh2 /dev/sdh3
 mtime of deleted disk is stale.

 Fix it by providing bd_part for the kobject_uevent().

 I have tested to confirm it doesn't break on the same thing
 when whole disk is used.

Reported-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Reported-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Anand Jain <Anand.Jain@oracle.com>
---
 fs/btrfs/volumes.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index f58ea9e..1aba687 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -124,7 +124,7 @@ static void btrfs_kobject_uevent(struct block_device *bdev,
 {
 	int ret;
 
-	ret = kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, action);
+	ret = kobject_uevent(&part_to_dev(bdev->bd_part)->kobj, action);
 	if (ret)
 		pr_warn("BTRFS: Sending event '%d' to kobject: '%s' (%p): failed\n",
 			action,
-- 
1.7.1