ovl: fix failure to fsync lower dir

As a writable mount, it is not expected for overlayfs to return EINVAL/EROFS for fsync, even if dir/file is not changed. This commit fixes the case of fsync of directory, which is easier to address, because overlayfs already implements fsync file operation for directories. The problem reported by Raphael is that new PostgreSQL 10.0 with a database in overlayfs where lower layer in squashfs fails to start. The failure is due to fsync error, when PostgreSQL does fsync on all existing db directories on startup and a specific directory exists lower layer with no changes. Reported-by: Raphael Hertzog <[email protected]> Cc: <[email protected]> # v3.18 Signed-off-by: Amir Goldstein <[email protected]> Tested-by: Raphaël Hertzog <[email protected]> Signed-off-by: Miklos Szeredi <[email protected]>
Freescale · Jan 19, 2018 · d796e77 · d796e77
1 parent 31747ed
commit d796e77
Showing 1 changed file with 5 additions and 1 deletion.
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
@@ -769,10 +769,14 @@ static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end,
 	struct dentry *dentry = file->f_path.dentry;
 	struct file *realfile = od->realfile;
 
+	/* Nothing to sync for lower */
+	if (!OVL_TYPE_UPPER(ovl_path_type(dentry)))
+		return 0;
+
 	/*
 	 * Need to check if we started out being a lower dir, but got copied up
 	 */
-	if (!od->is_upper && OVL_TYPE_UPPER(ovl_path_type(dentry))) {
+	if (!od->is_upper) {
 		struct inode *inode = file_inode(file);
 
 		realfile = READ_ONCE(od->upperfile);