Btrfs: fix the race between remove dev and alloc chunk

On remove device path, it updates device->dev_alloc_list but does not hold
chunk lock

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 43c4f09..ee197ec 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1291,7 +1291,9 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
        }
 
        if (device->writeable) {
+               lock_chunks(root);
                list_del_init(&device->dev_alloc_list);
+               unlock_chunks(root);
                root->fs_info->fs_devices->rw_devices--;
        }
 
@@ -1345,7 +1347,9 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
                }
                fs_devices->seed = device->fs_devices->seed;
                device->fs_devices->seed = NULL;
+               lock_chunks(root);
                __btrfs_close_devices(device->fs_devices);
+               unlock_chunks(root);
                free_fs_devices(device->fs_devices);
        }
 
@@ -1377,8 +1381,10 @@ out:
        return ret;
 error_undo:
        if (device->writeable) {
+               lock_chunks(root);
                list_add(&device->dev_alloc_list,
                         &root->fs_info->fs_devices->alloc_list);
+               unlock_chunks(root);
                root->fs_info->fs_devices->rw_devices++;
        }
        goto error_brelse;