[PATCH 5.10 004/663] debugfs: do not attempt to create a new file before the filesystem is initalized

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

commit 56348560d495d2501e87db559a61de717cd3ab02 upstream.

Some subsystems want to add debugfs files at early boot, way before
debugfs is initialized.  This seems to work somehow as the vfs layer
will not allow it to happen, but let's be explicit and test to ensure we
are properly up and running before allowing files to be created.

Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Reported-by: Michael Walle <michael@xxxxxxxx>
Reported-by: Marc Zyngier <maz@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210218100818.3622317-2-gregkh@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 fs/debugfs/inode.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -318,6 +318,9 @@ static struct dentry *start_creating(con
 	if (!(debugfs_allow & DEBUGFS_ALLOW_API))
 		return ERR_PTR(-EPERM);
 
+	if (!debugfs_initialized())
+		return ERR_PTR(-ENOENT);
+
 	pr_debug("creating file '%s'\n", name);
 
 	if (IS_ERR(parent))