linux-kernel - [RFC PATCH v5 02/10] ovl: implement ->writepages operation

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Date:   Thu, 23 Sep 2021 21:08:06 +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 02/10] ovl: implement ->writepages operation

Implement overlayfs' ->writepages operation so that
we can sync dirty data/metadata to upper filesystem.

Signed-off-by: Chengguang Xu <cgxu519@...ernel.net>
---
 fs/overlayfs/inode.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 832b17589733..d854e59a3710 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -659,9 +659,22 @@ static const struct inode_operations ovl_special_inode_operations = {
 	.update_time	= ovl_update_time,
 };
 
+static int ovl_writepages(struct address_space *mapping,
+			  struct writeback_control *wbc)
+{
+	struct inode *inode = mapping->host;
+	struct ovl_fs *ofs = inode->i_sb->s_fs_info;
+	struct inode *upper = ovl_inode_upper(inode);
+
+	if (!ovl_should_sync(ofs))
+		return 0;
+	return filemap_fdatawrite_wbc(upper->i_mapping, wbc);
+}
+
 static const struct address_space_operations ovl_aops = {
 	/* For O_DIRECT dentry_open() checks f_mapping->a_ops->direct_IO */
 	.direct_IO		= noop_direct_IO,
+	.writepages		= ovl_writepages,
 };
 
 /*
-- 
2.27.0