Executes filesystem sync or umount on overlayfs, dirty data does not be synced as expected on upper filesystem.
This patch fixes sync filesystem method to keep data consistency for overlayfs.
Signed-off-by: Chengguang Xu <cgxu@xxxxxxxxxxxx>
---
fs/overlayfs/super.c | 24 ++++++++++++++++++++----
1 file changed, 20 insertions(+), 4 deletions(-)
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index f5738e9..9c54345 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -17,6 +17,7 @@
#include <linux/statfs.h>
#include <linux/seq_file.h>
#include <linux/posix_acl_xattr.h>
+#include <linux/writeback.h>
#include "overlayfs.h"
#include "ovl_entry.h"
@@ -231,6 +232,7 @@ static void ovl_put_super(struct super_block *sb)
kfree(ufs);
}
+/* Sync real dirty inodes in upper filesystem (if it exists) */
static int ovl_sync_fs(struct super_block *sb, int wait)
{
struct ovl_fs *ufs = sb->s_fs_info;
@@ -240,12 +242,26 @@ static int ovl_sync_fs(struct super_block *sb, int wait)
if (!ufs->upper_mnt)
return 0;
upper_sb = ufs->upper_mnt->mnt_sb;
- if (!upper_sb->s_op->sync_fs)
- return 0;
- /* real inodes have already been synced by sync_filesystem(ovl_sb) */
down_read(&upper_sb->s_umount);
- ret = upper_sb->s_op->sync_fs(upper_sb, wait);
+ if (wait)
+ sync_inodes_sb(upper_sb);
+ else
+ writeback_inodes_sb(upper_sb, WB_REASON_SYNC);
+
+ if (upper_sb->s_op->sync_fs)
+ upper_sb->s_op->sync_fs(upper_sb, wait);
+
+ if (!upper_sb->s_bdev) {
+ up_read(&upper_sb->s_umount);
+ return 0;
+ }
+
+ if (wait)
+ ret = filemap_write_and_wait(upper_sb->s_bdev->bd_inode->i_mapping);
+ else
+ ret = filemap_flush(upper_sb->s_bdev->bd_inode->i_mapping);
+
up_read(&upper_sb->s_umount);
return ret;
}
--
1.8.3.1
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