On Mon, Apr 20, 2020 at 6:34 PM Filipe Manana <fdmanana@xxxxxxxxx> wrote:
>
> On Mon, Apr 20, 2020 at 6:50 AM Xiyu Yang <xiyuyang19@xxxxxxxxxxxx> wrote:
> >
> > btrfs_recover_relocation() invokes btrfs_join_transaction(), which joins
> > a btrfs_trans_handle object into transactions and returns a reference of
> > it with increased refcount to "trans".
> >
> > When btrfs_recover_relocation() returns, "trans" becomes invalid, so the
> > refcount should be decreased to keep refcount balanced.
> >
> > The reference counting issue happens in one exception handling path of
> > btrfs_recover_relocation(). When read_fs_root() failed, the refcnt
> > increased by btrfs_join_transaction() is not decreased, causing a refcnt
> > leak.
> >
> > Fix this issue by calling btrfs_end_transaction() on this error path
> > when read_fs_root() failed.
> >
> > Fixes: 79787eaab461 ("btrfs: replace many BUG_ONs with proper error
> > handling")
> > Signed-off-by: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx>
> > Signed-off-by: Xin Tan <tanxin.ctf@xxxxxxxxx>
>
> Reviewed-by: Filipe Manana <fdmanana@xxxxxxxx>
>
> Looks good, thanks.
Btw, the subject could be more clear.
Instead of
"btrfs: Fix refcnt leak in btrfs_recover_relocation"
something like
"btrfs: fix transaction leak in ..."
David can probably fixup that when he picks the patch.
Thanks.
>
> > ---
> > fs/btrfs/relocation.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
> > index 995d4b8b1cfd..46a451594c7a 100644
> > --- a/fs/btrfs/relocation.c
> > +++ b/fs/btrfs/relocation.c
> > @@ -4606,6 +4606,7 @@ int btrfs_recover_relocation(struct btrfs_root *root)
> > if (IS_ERR(fs_root)) {
> > err = PTR_ERR(fs_root);
> > list_add_tail(&reloc_root->root_list, &reloc_roots);
> > + btrfs_end_transaction(trans);
> > goto out_free;
> > }
> >
> > --
> > 2.7.4
> >
>
>
> --
> Filipe David Manana,
>
> “Whether you think you can, or you think you can't — you're right.”
--
Filipe David Manana,
“Whether you think you can, or you think you can't — you're right.”
