From: Miklos Szeredi <mszeredi@redhat.com>
Date: Wed, 18 Jul 2018 13:44:42 +0000 (+0200)
Subject: ovl: add ovl_fsync()
X-Git-Tag: Ubuntu-5.13.0-19.19~10331^2~47
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=de30dfd629e2e07e2e9d672b2931bcd60f9a34c0;p=mirror_ubuntu-jammy-kernel.git

ovl: add ovl_fsync()

Implement stacked fsync().

Don't sync if lower (noticed by Amir Goldstein).

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---

diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index 53d95c9d976a..8adddee93418 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -233,10 +233,33 @@ out_unlock:
 	return ret;
 }
 
+static int ovl_fsync(struct file *file, loff_t start, loff_t end, int datasync)
+{
+	struct fd real;
+	const struct cred *old_cred;
+	int ret;
+
+	ret = ovl_real_fdget(file, &real);
+	if (ret)
+		return ret;
+
+	/* Don't sync lower file for fear of receiving EROFS error */
+	if (file_inode(real.file) == ovl_inode_upper(file_inode(file))) {
+		old_cred = ovl_override_creds(file_inode(file)->i_sb);
+		ret = vfs_fsync_range(real.file, start, end, datasync);
+		revert_creds(old_cred);
+	}
+
+	fdput(real);
+
+	return ret;
+}
+
 const struct file_operations ovl_file_operations = {
 	.open		= ovl_open,
 	.release	= ovl_release,
 	.llseek		= ovl_llseek,
 	.read_iter	= ovl_read_iter,
 	.write_iter	= ovl_write_iter,
+	.fsync		= ovl_fsync,
 };