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From:   Chengguang Xu <cgxu519@mykernel.net>
To:     miklos@szeredi.hu, jack@suse.cz, amir73il@gmail.com
Cc:     linux-fsdevel@vger.kernel.org, linux-unionfs@vger.kernel.org,
        linux-kernel@vger.kernel.org, Chengguang Xu <cgxu519@mykernel.net>
Message-ID: <20210923130814.140814-8-cgxu519@mykernel.net>
Subject: [RFC PATCH v5 07/10] ovl: cache dirty overlayfs' inode
Date:   Thu, 23 Sep 2021 21:08:11 +0800
In-Reply-To: <20210923130814.140814-1-cgxu519@mykernel.net>
References: <20210923130814.140814-1-cgxu519@mykernel.net>
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Precedence: bulk

Now drop overlayfs' inode will sync dirty data,
so we change to only drop clean inode.

The purpose of doing this is to keep compatible
behavior with before because without this change
dropping overlayfs inode will not trigger syncing
of underlying dirty inode.

Signed-off-by: Chengguang Xu <cgxu519@mykernel.net>
---
 fs/overlayfs/super.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index cddae3ca2fa5..bf4000eb9be8 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -441,11 +441,25 @@ static int ovl_write_inode(struct inode *inode,
 =09return ret;
 }
=20
+/*
+ * In iput_final(), clean inode will drop directly and dirty inode will
+ * keep in the cache until write back to sync dirty data then add to lru
+ * list to wait reclaim.
+ */
+static int ovl_drop_inode(struct inode *inode)
+{
+=09struct inode *upper =3D ovl_inode_upper(inode);
+
+=09if (!upper || !(inode->i_state & I_DIRTY_ALL))
+=09=09return 1;
+=09return generic_drop_inode(inode);
+}
+
 static const struct super_operations ovl_super_operations =3D {
 =09.alloc_inode=09=3D ovl_alloc_inode,
 =09.free_inode=09=3D ovl_free_inode,
 =09.destroy_inode=09=3D ovl_destroy_inode,
-=09.drop_inode=09=3D generic_delete_inode,
+=09.drop_inode=09=3D ovl_drop_inode,
 =09.evict_inode=09=3D ovl_evict_inode,
 =09.write_inode=09=3D ovl_write_inode,
 =09.put_super=09=3D ovl_put_super,
--=20
2.27.0