On Fri, Jul 20, 2018 at 04:11:29PM +0300, Nikolay Borisov wrote:
>
>
> On 19.07.2018 17:49, Josef Bacik wrote:
> > From: Josef Bacik <jbacik@xxxxxx>
> >
> > We do this dance in cleanup_ref_head and check_ref_cleanup, unify it
> > into a helper and cleanup the calling functions.
> >
> > Signed-off-by: Josef Bacik <jbacik@xxxxxx>
> > ---
> > fs/btrfs/delayed-ref.c | 14 ++++++++++++++
> > fs/btrfs/delayed-ref.h | 3 ++-
> > fs/btrfs/extent-tree.c | 24 ++++--------------------
> > 3 files changed, 20 insertions(+), 21 deletions(-)
> >
> > diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c
> > index 03dec673d12a..e1b322d651dd 100644
> > --- a/fs/btrfs/delayed-ref.c
> > +++ b/fs/btrfs/delayed-ref.c
> > @@ -393,6 +393,20 @@ btrfs_select_ref_head(struct btrfs_trans_handle *trans)
> > return head;
> > }
> >
> > +void btrfs_delete_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
> > + struct btrfs_delayed_ref_head *head)
> > +{
> > + lockdep_assert_held(&delayed_refs->lock);
> > + lockdep_assert_held(&head->lock);
> > +
> > + rb_erase(&head->href_node, &delayed_refs->href_root);
> > + RB_CLEAR_NODE(&head->href_node);
> > + atomic_dec(&delayed_refs->num_entries);
> > + delayed_refs->num_heads--;
> > + if (head->processing == 0)
> > + delayed_refs->num_heads_ready--;
> > +}
> > +
> > /*
> > * Helper to insert the ref_node to the tail or merge with tail.
> > *
> > diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h
> > index ea1aecb6a50d..36318182e4ec 100644
> > --- a/fs/btrfs/delayed-ref.h
> > +++ b/fs/btrfs/delayed-ref.h
> > @@ -263,7 +263,8 @@ static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
> > {
> > mutex_unlock(&head->mutex);
> > }
> > -
> > +void btrfs_delete_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
> > + struct btrfs_delayed_ref_head *head);
> >
> > struct btrfs_delayed_ref_head *
> > btrfs_select_ref_head(struct btrfs_trans_handle *trans);
> > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> > index 3d9fe58c0080..ccaccd78534e 100644
> > --- a/fs/btrfs/extent-tree.c
> > +++ b/fs/btrfs/extent-tree.c
> > @@ -2577,12 +2577,9 @@ static int cleanup_ref_head(struct btrfs_trans_handle *trans,
> > spin_unlock(&delayed_refs->lock);
> > return 1;
> > }
> > - delayed_refs->num_heads--;
> > - rb_erase(&head->href_node, &delayed_refs->href_root);
> > - RB_CLEAR_NODE(&head->href_node);
> > - spin_unlock(&head->lock);
> > + btrfs_delete_ref_head(delayed_refs, head);
> > spin_unlock(&delayed_refs->lock);
> > - atomic_dec(&delayed_refs->num_entries);
> > + spin_unlock(&head->lock);
> >
> > trace_run_delayed_ref_head(fs_info, head, 0);
> >
> > @@ -7122,22 +7119,9 @@ static noinline int check_ref_cleanup(struct btrfs_trans_handle *trans,
> > if (!mutex_trylock(&head->mutex))
> > goto out;
> >
> > - /*
> > - * at this point we have a head with no other entries. Go
> > - * ahead and process it.
> > - */
> > - rb_erase(&head->href_node, &delayed_refs->href_root);
> > - RB_CLEAR_NODE(&head->href_node);
> > - atomic_dec(&delayed_refs->num_entries);
> > -
> > - /*
> > - * we don't take a ref on the node because we're removing it from the
> > - * tree, so we just steal the ref the tree was holding.
> > - */
> > - delayed_refs->num_heads--;
> > - if (head->processing == 0)
> > - delayed_refs->num_heads_ready--;
>
> In cleanup_ref_head we don't have the num_heads_ready-- code so this is
> not pure consolidation but changes the behavior to a certain extent. It
> seems this patch is also fixing a bug w.r.t num_heads_ready counts if
> so, this needs to be documented in the changelog.
>
No it's not, because cleanup_ref_head is called when running delayed refs, so
head->processing == 1, which means there's no change. Thanks,
Josef
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