FS-Cache: Add transition to handle invalidate immediately after lookup

Add a missing transition to the FS-Cache object state machine to handle an
invalidation event occuring between the back end completing the object lookup
by calling fscache_obtained_object() (which moves to state OBJECT_AVAILABLE)
and the backend returning to fscache_lookup_object() and thence to
fscache_object_state_machine() which then does a goto lookup_transit to handle
the transition - but lookup_transit doesn't handle EV_INVALIDATE.

Without this, the following BUG can be logged:

	FS-Cache: Unsupported event 2 [5/f7] in state OBJECT_AVAILABLE
	------------[ cut here ]------------
	kernel BUG at fs/fscache/object.c:357!

Where event 2 is EV_INVALIDATE.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/fscache/object.c b/fs/fscache/object.c
index 2c512cbac380..50d41c180211 100644
--- a/fs/fscache/object.c
+++ b/fs/fscache/object.c
@@ -284,6 +284,9 @@ lookup_transit:
         case FSCACHE_OBJECT_EV_ERROR:
                 new_state = FSCACHE_OBJECT_LC_DYING;
                 goto change_state;
+        case FSCACHE_OBJECT_EV_INVALIDATE:
+                new_state = FSCACHE_OBJECT_INVALIDATING;
+                goto change_state;
         case FSCACHE_OBJECT_EV_REQUEUE:
                 goto done;
         case -1: