Btrfs: fix the race between reading and updating devices
On btrfs_congested_fn and __unplug_io_fn paths, we should hold
device_list_mutex to avoid remove/add device path to
update fs_devices->devices
On __btrfs_close_devices and btrfs_prepare_sprout paths, the devices in
fs_devices->devices or fs_devices->devices is updated, so we should hold
the mutex to avoid the reader side to reach them
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 64b2896..4e53a4f 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1410,6 +1410,7 @@
struct btrfs_device *device;
struct backing_dev_info *bdi;
+ mutex_lock(&info->fs_devices->device_list_mutex);
list_for_each_entry(device, &info->fs_devices->devices, dev_list) {
if (!device->bdev)
continue;
@@ -1419,6 +1420,7 @@
break;
}
}
+ mutex_unlock(&info->fs_devices->device_list_mutex);
return ret;
}