From 9089b9d08fc04c08948b0496b584c4be0dd249f8 Mon Sep 17 00:00:00 2001
From: Chengguang Xu <cgxu519@mykernel.net>
Date: Wed, 22 Apr 2020 12:28:43 +0800
Subject: [PATCH] ovl: sync dirty data when remounting to ro mode
sync_filesystem() does not sync dirty data for readonly filesystem during
umount, so before changing to readonly filesystem we should sync dirty data
for data integrity.
Signed-off-by: Chengguang Xu <cgxu519@mykernel.net>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
fs/overlayfs/super.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index a88a7badf4441..60dfb27bc12bc 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -365,11 +365,20 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
static int ovl_remount(struct super_block *sb, int *flags, char *data)
{
struct ovl_fs *ofs = sb->s_fs_info;
+ struct super_block *upper_sb;
+ int ret = 0;
if (!(*flags & SB_RDONLY) && ovl_force_readonly(ofs))
return -EROFS;
- return 0;
+ if (*flags & SB_RDONLY && !sb_rdonly(sb)) {
+ upper_sb = ofs->upper_mnt->mnt_sb;
+ down_read(&upper_sb->s_umount);
+ ret = sync_filesystem(upper_sb);
+ up_read(&upper_sb->s_umount);
+ }
+
+ return ret;
}
static const struct super_operations ovl_super_operations = {
--
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