[PATCH v6 10/22] erofs: add mode checking helper

[Jeffle Xu]

Until then erofs is exactly blockdev based filesystem. In other using
scenarios (e.g. container image), erofs needs to run upon files.

This patch set is going to introduces a new nodev mode, in which erofs
could be mounted from a bootstrap blob file containing complete erofs
image.

Add a helper checking which mode erofs works in.

Signed-off-by: Jeffle Xu <jefflexu at linux.alibaba.com>
---
 fs/erofs/internal.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index e424293f47a2..1486e2573667 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -161,6 +161,11 @@ struct erofs_sb_info {
 #define set_opt(opt, option)	((opt)->mount_opt |= EROFS_MOUNT_##option)
 #define test_opt(opt, option)	((opt)->mount_opt & EROFS_MOUNT_##option)
 
+static inline bool erofs_is_nodev_mode(struct super_block *sb)
+{
+	return !sb->s_bdev;
+}
+
 enum {
 	EROFS_ZIP_CACHE_DISABLED,
 	EROFS_ZIP_CACHE_READAHEAD,
-- 
2.27.0