On Thu, Dec 01, 2016 at 01:44:19PM -0800, Liu Bo wrote: > If @block_group is not @used_bg, it'll try to get @used_bg's lock without > droping @block_group 's lock and lockdep has throwed a scary deadlock warning > about it. > Fix it by using down_read_nested. > > Signed-off-by: Liu Bo <bo.li....@oracle.com> > --- > fs/btrfs/extent-tree.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c > index 210c94a..cdb082a 100644 > --- a/fs/btrfs/extent-tree.c > +++ b/fs/btrfs/extent-tree.c > @@ -7394,7 +7394,8 @@ btrfs_lock_cluster(struct btrfs_block_group_cache > *block_group, > > spin_unlock(&cluster->refill_lock); > > - down_read(&used_bg->data_rwsem); > + /* We should only have one-level nested. */ > + down_read_nested(&used_bg->data_rwsem, 1);
While looking what down_read_nested does, I've found SINGLE_DEPTH_NESTING, defined to 1. I'd rather use it instead of '1', as it gives more more pointers to the docs. -- 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
