btrfs: fix rw_devices miss match after seed replace

reproducer:
    reproducer:
    mount /dev/sdb /btrfs
    btrfs dev add /dev/sdc /btrfs
    btrfs rep start -B /dev/sdb /dev/sdd /btrfs
    umount /btrfs

WARNING: CPU: 0 PID: 3882 at fs/btrfs/volumes.c:892 __btrfs_close_devices+0x1c8/0x200 [btrfs]()

which is

        WARN_ON(fs_devices->rw_devices);

   The problem here is that we did not add one to the rw_devices when
   we replace the seed device with a writable device.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Chris Mason <clm@fb.com>

diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index eea26e1b2fda1d21230dd5f1e01e25f8fb23a3e8..fb0a7fa2f70cd1d9da174493f26a9de44712e2e3 100644 (file)
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -562,6 +562,8 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
        if (fs_info->fs_devices->latest_bdev == src_device->bdev)
                fs_info->fs_devices->latest_bdev = tgt_device->bdev;
        list_add(&tgt_device->dev_alloc_list, &fs_info->fs_devices->alloc_list);
+       if (src_device->fs_devices->seeding)
+               fs_info->fs_devices->rw_devices++;
 
        /* replace the sysfs entry */
        btrfs_kobj_rm_device(fs_info, src_device);