[PATCH v3 2/3] ovl: add ovl_allow_offline_changes() helper

[Vyacheslav Yurkov <uvv.mail@gmail.com>]

From: Vyacheslav Yurkov <Vyacheslav.Yurkov@bruker.com>

Allows to check whether any of extended features are enabled

Signed-off-by: Vyacheslav Yurkov <Vyacheslav.Yurkov@bruker.com>
---
 fs/overlayfs/overlayfs.h | 12 ++++++++++++
 fs/overlayfs/super.c     |  4 +---
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 6ec73db4bf9e..29d71f253db4 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -262,6 +262,18 @@ static inline bool ovl_open_flags_need_copy_up(int flags)
 	return ((OPEN_FMODE(flags) & FMODE_WRITE) || (flags & O_TRUNC));
 }
 
+static inline bool ovl_allow_offline_changes(struct ovl_fs *ofs)
+{
+	/*
+	 * To avoid regressions in existing setups with overlay lower offline
+	 * changes, we allow lower changes only if none of the new features
+	 * are used.
+	 */
+	return (!ofs->config.index && !ofs->config.metacopy &&
+		!ofs->config.redirect_dir && ofs->config.xino != OVL_XINO_ON);
+}
+
+
 /* util.c */
 int ovl_want_write(struct dentry *dentry);
 void ovl_drop_write(struct dentry *dentry);
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 97ea35fdd933..178daa5e82c9 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -1599,9 +1599,7 @@ static bool ovl_lower_uuid_ok(struct ovl_fs *ofs, const uuid_t *uuid)
 	 * user opted-in to one of the new features that require following the
 	 * lower inode of non-dir upper.
 	 */
-	if (!ofs->config.index && !ofs->config.metacopy &&
-	    !ofs->config.redirect_dir && ofs->config.xino != OVL_XINO_ON &&
-	    uuid_is_null(uuid))
+	if (ovl_allow_offline_changes(ofs) && uuid_is_null(uuid))
 		return false;
 
 	for (i = 0; i < ofs->numfs; i++) {
-- 
2.25.1