ovl: check if all layers are on the same fs
Some features can only work when all layers are on the same fs. Test this
condition during mount time, so features can check them later.
Add helper ovl_same_sb() to return the common super block in case all
layers are on the same fs.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 35b8959d..2bd4c26 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -41,6 +41,13 @@ const struct cred *ovl_override_creds(struct super_block *sb)
return override_creds(ofs->creator_cred);
}
+struct super_block *ovl_same_sb(struct super_block *sb)
+{
+ struct ovl_fs *ofs = sb->s_fs_info;
+
+ return ofs->same_sb;
+}
+
struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
{
size_t size = offsetof(struct ovl_entry, lowerstack[numlower]);