[PATCH v3] ovl: inode reference leak in ovl_is_inuse true case.

[youngjun <her0gyugyu@gmail.com>]

When "ovl_is_inuse" true case, trap inode reference not put.
plus adding the comment explaining sequence of
ovl_is_inuse after ovl_setup_trap.

Fixes: 0be0bfd2de9d ("ovl: fix regression caused by overlapping layers..")
Cc: <stable@vger.kernel.org> # v4.19+
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
> Signed-off-by: youngjun <her0gyugyu@gmail.com>
> ---
>  fs/overlayfs/super.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
> index 91476bc422f9..0396793dadb8 100644
> --- a/fs/overlayfs/super.c
> +++ b/fs/overlayfs/super.c
> @@ -1029,6 +1029,12 @@ static const struct xattr_handler *ovl_xattr_handlers[] = {
>         NULL
>  };
>
> +/*
> + * Check if lower root conflicts with this overlay layers before checking
> + * if it is in-use as upperdir/workdir of "another" mount, because we do
> + * not bother to check in ovl_is_inuse() if the upperdir/workdir is in fact
> + * in-use by our upperdir/workdir.
> + */

Signed-off-by: youngjun <her0gyugyu@gmail.com>
---
 fs/overlayfs/super.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 91476bc422f9..3097142b1e23 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -1493,14 +1493,22 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
 		if (err < 0)
 			goto out;
 
+		/*
+		 * Check if lower root conflicts with this overlay layers before checking
+		 * if it is in-use as upperdir/workdir of "another" mount, because we do
+		 * not bother to check in ovl_is_inuse() if the upperdir/workdir is in fact
+		 * in-use by our upperdir/workdir.
+		 */
 		err = ovl_setup_trap(sb, stack[i].dentry, &trap, "lowerdir");
 		if (err)
 			goto out;
 
 		if (ovl_is_inuse(stack[i].dentry)) {
 			err = ovl_report_in_use(ofs, "lowerdir");
-			if (err)
+			if (err) {
+				iput(trap);
 				goto out;
+			}
 		}
 
 		mnt = clone_private_mount(&stack[i]);
-- 
2.17.1

Great thanks Amir. guidance to me really helpful.
As you comment, I modified my patch.

1) I revised three patch so version is 3.
2) I misunderstood your comment(adding annotation) firstly. 
But, I clearly know at now and modified it.
the annotation before "ovl_setup_trap" is clearly understood as I see.

And I have some questions.

1) As I understand, The CC you said valid is 'linux-unionfs'?
2) The comment "Please add these lines to the bottom of commit message..."
   Is it needed manually when I revised patch?