FS-Cache: Permit cache retrieval ops to be interrupted in the initial wait phase

[safe/jmp/linux-2.6] / fs / fscache / operation.c

diff --git a/fs/fscache/operation.c b/fs/fscache/operation.c
index 09e43b6..296492e 100644 (file)
--- a/fs/fscache/operation.c
+++ b/fs/fscache/operation.c
@@ -34,32 +34,31 @@ void fscache_enqueue_operation(struct fscache_operation *op)
 
        fscache_set_op_state(op, "EnQ");
 
+       ASSERT(list_empty(&op->pend_link));
        ASSERT(op->processor != NULL);
        ASSERTCMP(op->object->state, >=, FSCACHE_OBJECT_AVAILABLE);
        ASSERTCMP(atomic_read(&op->usage), >, 0);
 
-       if (list_empty(&op->pend_link)) {
-               switch (op->flags & FSCACHE_OP_TYPE) {
-               case FSCACHE_OP_FAST:
-                       _debug("queue fast");
-                       atomic_inc(&op->usage);
-                       if (!schedule_work(&op->fast_work))
-                               fscache_put_operation(op);
-                       break;
-               case FSCACHE_OP_SLOW:
-                       _debug("queue slow");
-                       slow_work_enqueue(&op->slow_work);
-                       break;
-               case FSCACHE_OP_MYTHREAD:
-                       _debug("queue for caller's attention");
-                       break;
-               default:
-                       printk(KERN_ERR "FS-Cache: Unexpected op type %lx",
-                              op->flags);
-                       BUG();
-                       break;
-               }
-               fscache_stat(&fscache_n_op_enqueue);
+       fscache_stat(&fscache_n_op_enqueue);
+       switch (op->flags & FSCACHE_OP_TYPE) {
+       case FSCACHE_OP_FAST:
+               _debug("queue fast");
+               atomic_inc(&op->usage);
+               if (!schedule_work(&op->fast_work))
+                       fscache_put_operation(op);
+               break;
+       case FSCACHE_OP_SLOW:
+               _debug("queue slow");
+               slow_work_enqueue(&op->slow_work);
+               break;
+       case FSCACHE_OP_MYTHREAD:
+               _debug("queue for caller's attention");
+               break;
+       default:
+               printk(KERN_ERR "FS-Cache: Unexpected op type %lx",
+                      op->flags);
+               BUG();
+               break;
        }
 }
 EXPORT_SYMBOL(fscache_enqueue_operation);
@@ -97,6 +96,7 @@ int fscache_submit_exclusive_op(struct fscache_object *object,
        spin_lock(&object->lock);
        ASSERTCMP(object->n_ops, >=, object->n_in_progress);
        ASSERTCMP(object->n_ops, >=, object->n_exclusive);
+       ASSERT(list_empty(&op->pend_link));
 
        ret = -ENOBUFS;
        if (fscache_object_is_active(object)) {
@@ -202,6 +202,7 @@ int fscache_submit_op(struct fscache_object *object,
        spin_lock(&object->lock);
        ASSERTCMP(object->n_ops, >=, object->n_in_progress);
        ASSERTCMP(object->n_ops, >=, object->n_exclusive);
+       ASSERT(list_empty(&op->pend_link));
 
        ostate = object->state;
        smp_rmb();
@@ -273,12 +274,7 @@ void fscache_start_operations(struct fscache_object *object)
                        stop = true;
                }
                list_del_init(&op->pend_link);
-               object->n_in_progress++;
-
-               if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
-                       wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
-               if (op->processor)
-                       fscache_enqueue_operation(op);
+               fscache_run_op(object, op);
 
                /* the pending queue was holding a ref on the object */
                fscache_put_operation(op);
@@ -291,6 +287,36 @@ void fscache_start_operations(struct fscache_object *object)
 }
 
 /*
+ * cancel an operation that's pending on an object
+ */
+int fscache_cancel_op(struct fscache_operation *op)
+{
+       struct fscache_object *object = op->object;
+       int ret;
+
+       _enter("OBJ%x OP%x}", op->object->debug_id, op->debug_id);
+
+       spin_lock(&object->lock);
+
+       ret = -EBUSY;
+       if (!list_empty(&op->pend_link)) {
+               fscache_stat(&fscache_n_op_cancelled);
+               list_del_init(&op->pend_link);
+               object->n_ops--;
+               if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
+                       object->n_exclusive--;
+               if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
+                       wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
+               fscache_put_operation(op);
+               ret = 0;
+       }
+
+       spin_unlock(&object->lock);
+       _leave(" = %d", ret);
+       return ret;
+}
+
+/*
  * release an operation
  * - queues pending ops if this is the last in-progress op
  */