Implement overlayfs' ->writepages operation so that
we can sync dirty data/metadata to upper filesystem.
If writeback mode is sync_mode we add overlayfs inode
to extra syncfs wait list so that we can wait completion
in ->syncfs.
Signed-off-by: Chengguang Xu <cgxu519@xxxxxxxxxxxx>
---
fs/overlayfs/inode.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index b584dca845ba..1f5cbbc60b28 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -11,6 +11,7 @@
#include <linux/posix_acl.h>
#include <linux/ratelimit.h>
#include <linux/fiemap.h>
+#include <linux/writeback.h>
#include "overlayfs.h"
@@ -516,7 +517,30 @@ 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);
+ int ret;
+
+ if (!ovl_should_sync(ofs))
+ return 0;
+ ret = sync_inode(upper, wbc);
+ if (!ret && wbc->for_sync == 1) {
+ spin_lock(&ofs->syncfs_wait_list_lock);
+ if (list_empty(&OVL_I(inode)->wait_list))
+ list_add_tail(&OVL_I(inode)->wait_list,
+ &ofs->syncfs_wait_list);
+ spin_unlock(&ofs->syncfs_wait_list_lock);
+ }
+
+ return ret;
+}
+
static const struct address_space_operations ovl_aops = {
+ .writepages = ovl_writepages,
/* For O_DIRECT dentry_open() checks f_mapping->a_ops->direct_IO */
.direct_IO = noop_direct_IO,
};
--
2.26.2
