linux-kernel - [RFC PATCH v5 07/10] ovl: cache dirty overlayfs' inode

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 23 Sep 2021 21:08:11 +0800
From:   Chengguang Xu <cgxu519@...ernel.net>
To:     miklos@...redi.hu, jack@...e.cz, amir73il@...il.com
Cc:     linux-fsdevel@...r.kernel.org, linux-unionfs@...r.kernel.org,
        linux-kernel@...r.kernel.org, Chengguang Xu <cgxu519@...ernel.net>
Subject: [RFC PATCH v5 07/10] ovl: cache dirty overlayfs' inode

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@...ernel.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,
 	return ret;
 }
 
+/*
+ * 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)
+{
+	struct inode *upper = ovl_inode_upper(inode);
+
+	if (!upper || !(inode->i_state & I_DIRTY_ALL))
+		return 1;
+	return generic_drop_inode(inode);
+}
+
 static const struct super_operations ovl_super_operations = {
 	.alloc_inode	= ovl_alloc_inode,
 	.free_inode	= ovl_free_inode,
 	.destroy_inode	= ovl_destroy_inode,
-	.drop_inode	= generic_delete_inode,
+	.drop_inode	= ovl_drop_inode,
 	.evict_inode	= ovl_evict_inode,
 	.write_inode	= ovl_write_inode,
 	.put_super	= ovl_put_super,
-- 
2.27.0