linux-kernel - [RFC PATCH v5 06/10] ovl: implement overlayfs' ->write

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Date:   Thu, 23 Sep 2021 21:08:10 +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 06/10] ovl: implement overlayfs' ->write_inode operation

Implement overlayfs' ->write_inode to sync dirty data
and redirty overlayfs' inode if necessary.

Signed-off-by: Chengguang Xu <cgxu519@...ernel.net>
---
 fs/overlayfs/super.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 2ab77adf7256..cddae3ca2fa5 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -412,12 +412,42 @@ static void ovl_evict_inode(struct inode *inode)
 	clear_inode(inode);
 }
 
+static int ovl_write_inode(struct inode *inode,
+			   struct writeback_control *wbc)
+{
+	struct ovl_fs *ofs = inode->i_sb->s_fs_info;
+	struct inode *upper = ovl_inode_upper(inode);
+	unsigned long iflag = 0;
+	int ret = 0;
+
+	if (!upper)
+		return 0;
+
+	if (!ovl_should_sync(ofs))
+		return 0;
+
+	if (upper->i_sb->s_op->write_inode)
+		ret = upper->i_sb->s_op->write_inode(inode, wbc);
+
+	if (mapping_writably_mapped(upper->i_mapping) ||
+	    mapping_tagged(upper->i_mapping, PAGECACHE_TAG_WRITEBACK))
+		iflag |= I_DIRTY_PAGES;
+
+	iflag |= upper->i_state & I_DIRTY_ALL;
+
+	if (iflag)
+		ovl_mark_inode_dirty(inode);
+
+	return ret;
+}
+
 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,
 	.evict_inode	= ovl_evict_inode,
+	.write_inode	= ovl_write_inode,
 	.put_super	= ovl_put_super,
 	.sync_fs	= ovl_sync_fs,
 	.statfs		= ovl_statfs,
-- 
2.27.0