[PATCH 4.18 135/197] btrfs: fix in-memory value of total_devices after seed device deletion

[Greg Kroah-Hartman]

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Anand Jain <anand.jain@xxxxxxxxxx>

[ Upstream commit b4993e64f78a9605b45252fa9ba385c88a1f4ce9 ]

In case of deleting the seed device the %cur_devices (seed) and the
%fs_devices (parent) are different. Now, as the parent
fs_devices::total_devices also maintains the total number of devices
including the seed device, so decrement its in-memory value for the
successful seed delete. We are already updating its corresponding
on-disk btrfs_super_block::number_devices value.

Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 fs/btrfs/volumes.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2029,6 +2029,9 @@ int btrfs_rm_device(struct btrfs_fs_info
 
 	cur_devices->num_devices--;
 	cur_devices->total_devices--;
+	/* Update total_devices of the parent fs_devices if it's seed */
+	if (cur_devices != fs_devices)
+		fs_devices->total_devices--;
 
 	if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state))
 		cur_devices->missing_devices--;