FS-Cache: Annotate slow-work runqueue proc lines for FS-Cache work items

Annotate slow-work runqueue proc lines for FS-Cache work items.  Objects
include the object ID and the state.  Operations include the object ID, the
operation ID and the operation type and state.

Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/fs/fscache/operation.c b/fs/fscache/operation.c
index f1a2857..91bbe6f 100644
--- a/fs/fscache/operation.c
+++ b/fs/fscache/operation.c
@@ -13,6 +13,7 @@
 
 #define FSCACHE_DEBUG_LEVEL OPERATION
 #include <linux/module.h>
+#include <linux/seq_file.h>
 #include "internal.h"
 
 atomic_t fscache_op_debug_id;
@@ -31,6 +32,8 @@
 	_enter("{OBJ%x OP%x,%u}",
 	       op->object->debug_id, op->debug_id, atomic_read(&op->usage));
 
+	fscache_set_op_state(op, "EnQ");
+
 	ASSERT(op->processor != NULL);
 	ASSERTCMP(op->object->state, >=, FSCACHE_OBJECT_AVAILABLE);
 	ASSERTCMP(atomic_read(&op->usage), >, 0);
@@ -67,6 +70,8 @@
 static void fscache_run_op(struct fscache_object *object,
 			   struct fscache_operation *op)
 {
+	fscache_set_op_state(op, "Run");
+
 	object->n_in_progress++;
 	if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
 		wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
@@ -87,6 +92,8 @@
 
 	_enter("{OBJ%x OP%x},", object->debug_id, op->debug_id);
 
+	fscache_set_op_state(op, "SubmitX");
+
 	spin_lock(&object->lock);
 	ASSERTCMP(object->n_ops, >=, object->n_in_progress);
 	ASSERTCMP(object->n_ops, >=, object->n_exclusive);
@@ -190,6 +197,8 @@
 
 	ASSERTCMP(atomic_read(&op->usage), >, 0);
 
+	fscache_set_op_state(op, "Submit");
+
 	spin_lock(&object->lock);
 	ASSERTCMP(object->n_ops, >=, object->n_in_progress);
 	ASSERTCMP(object->n_ops, >=, object->n_exclusive);
@@ -298,6 +307,8 @@
 	if (!atomic_dec_and_test(&op->usage))
 		return;
 
+	fscache_set_op_state(op, "Put");
+
 	_debug("PUT OP");
 	if (test_and_set_bit(FSCACHE_OP_DEAD, &op->flags))
 		BUG();
@@ -452,9 +463,27 @@
 	_leave("");
 }
 
+/*
+ * describe an operation for slow-work debugging
+ */
+#ifdef CONFIG_SLOW_WORK_PROC
+static void fscache_op_desc(struct slow_work *work, struct seq_file *m)
+{
+	struct fscache_operation *op =
+		container_of(work, struct fscache_operation, slow_work);
+
+	seq_printf(m, "FSC: OBJ%x OP%x: %s/%s fl=%lx",
+		   op->object->debug_id, op->debug_id,
+		   op->name, op->state, op->flags);
+}
+#endif
+
 const struct slow_work_ops fscache_op_slow_work_ops = {
 	.owner		= THIS_MODULE,
 	.get_ref	= fscache_op_get_ref,
 	.put_ref	= fscache_op_put_ref,
 	.execute	= fscache_op_execute,
+#ifdef CONFIG_SLOW_WORK_PROC
+	.desc		= fscache_op_desc,
+#endif
 };