Re: [PATCH 4/8] btrfs: free the reloc_control in a consistent way

[David Sterba <dsterba@suse.cz>]

On Thu, Mar 05, 2020 at 07:39:33PM +0800, Qu Wenruo wrote:
> 
> 
> On 2020/3/5 上午12:18, Josef Bacik wrote:
> > If we have an error while processing the reloc roots we could leak roots
> > that were added to rc->reloc_roots before we hit the error.  We could
> > have also not removed the reloct tree mapping from our rb_tree, so clean
> > up any remaining nodes in the reloc root rb_tree.
> > 
> > Signed-off-by: Josef Bacik <josef@toxicpanda.com>
> > ---
> >  fs/btrfs/relocation.c | 18 ++++++++++++++++--
> >  1 file changed, 16 insertions(+), 2 deletions(-)
> > 
> > diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
> > index c496f8ed8c7e..f6237d885fe0 100644
> > --- a/fs/btrfs/relocation.c
> > +++ b/fs/btrfs/relocation.c
> > @@ -4387,6 +4387,20 @@ static struct reloc_control *alloc_reloc_control(struct btrfs_fs_info *fs_info)
> >  	return rc;
> >  }
> >  
> > +static void free_reloc_control(struct reloc_control *rc)
> > +{
> > +	struct rb_node *rb_node;
> > +	struct mapping_node *node;
> > +
> > +	free_reloc_roots(&rc->reloc_roots);
> > +	while ((rb_node = rb_first(&rc->reloc_root_tree.rb_root))) {
> 
> rbtree_postorder_for_each_entry_safe().
> 
> So that we don't need to bother the re-balance of rbtree.

I'll update the patch with this

--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -4240,15 +4240,13 @@ static struct reloc_control *alloc_reloc_control(struct btrfs_fs_info *fs_info)
 
 static void free_reloc_control(struct reloc_control *rc)
 {
-       struct rb_node *rb_node;
-       struct mapping_node *node;
+       struct mapping_node *node, *tmp;
 
        free_reloc_roots(&rc->reloc_roots);
-       while ((rb_node = rb_first(&rc->reloc_root_tree.rb_root))) {
-               node = rb_entry(rb_node, struct mapping_node, rb_node);
-               rb_erase(rb_node, &rc->reloc_root_tree.rb_root);
+       rbtree_postorder_for_each_entry_safe(node, tmp,
+                       &rc->reloc_root_tree.rb_root, rb_node)
                kfree(node);
-       }
+
        kfree(rc);
 }