When debugging journal-cleanup issues, stale journal_head attachments on
buffer_heads can cause crashes on subsequent mounts.
Add detection logic in bh_cache_clear() to warn when a buffer_head still
has a journal_head attached. This indicates the journal was not properly
destroyed before unmount. Clear the JBD flag and pointer to prevent
issues with subsequent mounts.
Co-developed-by: Claude Opus 4.5 <noreply@anthropic.com>
Signed-off-by: Simon Glass <simon.glass@canonical.com>
014f082f05