Re: [PATCH v2] Btrfs: set keep_lock when necessary in btrfs_defrag_leaves

[David Sterba <dsterba@suse.cz>]

On Fri, Apr 27, 2018 at 11:23:23AM +0800, Liu Bo wrote:
> >> ---
> >> v2: update commit log with more details.
> >>
> >>  fs/btrfs/tree-defrag.c | 3 +--
> >>  1 file changed, 1 insertion(+), 2 deletions(-)
> >>
> >> diff --git a/fs/btrfs/tree-defrag.c b/fs/btrfs/tree-defrag.c
> >> index 3c0987ab587d..c12747904d4c 100644
> >> --- a/fs/btrfs/tree-defrag.c
> >> +++ b/fs/btrfs/tree-defrag.c
> >> @@ -65,8 +65,6 @@ int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
> >>               memcpy(&key, &root->defrag_progress, sizeof(key));
> >>       }
> >>
> >> -     path->keep_locks = 1;
> >> -
> >>       ret = btrfs_search_forward(root, &key, path, BTRFS_OLDEST_GENERATION);
> >
> > What does btrfs_search_forward do as the first statement:
> >
> > 5115 int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
> > 5116                          struct btrfs_path *path,
> > 5117                          u64 min_trans)
> > 5118 {
> > .... declarations
> > 5128
> > 5129         path->keep_locks = 1;
> >
> > So even if removed from above, there will be no change. The value of
> > keep_locks is preserved after btrfs_path_release.
> >
> 
> It will set it back,
> 
> out:
>         path->keep_locks = keep_locks;

Oh, right. So much for reading the whole function.