On 09/03/2014 09:35 AM, Miao Xie wrote: > There were several problems about chunk mutex usage: > - Lock chunk mutex when updating metadata. It would cause the nested > deadlock because updating metadata might need allocate new chunks > that need acquire chunk mutex. We remove chunk mutex at this case, > because b-tree lock and other lock mechanism can help us. > - ABBA deadlock occured between device_list_mutex and chunk_mutex. > When we update device status, we must acquire device_list_mutex at the > beginning, and then we might get chunk_mutex during the device status > update because we need allocate new chunks for metadata COW. But at > most place, we acquire chunk_mutex at first and then acquire device list > mutex. We need change the lock order. > - Some place we needn't acquire chunk_mutex. For example we needn't get > chunk_mutex when we free a empty seed fs_devices structure. > > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c > index 9f22398d..357f911 100644 > --- a/fs/btrfs/volumes.c > +++ b/fs/btrfs/volumes.c > > @@ -2619,10 +2615,23 @@ static int btrfs_relocate_chunk(struct btrfs_root > *root, > map = (struct map_lookup *)em->bdev; > > for (i = 0; i < map->num_stripes; i++) { > - ret = btrfs_free_dev_extent(trans, map->stripes[i].dev, > - map->stripes[i].physical); > + device = map->stripes[i].dev; > + ret = btrfs_free_dev_extent(trans, device, > + map->stripes[i].physical, > + &dev_extent_len); > BUG_ON(ret);
gcc is worried that dev_extent_len may be used uninitialized here. The BUG_ON makes it unlikely we'll notice dev_extent_len, but I set it to zero in my version here. -chris -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html