1 files changed, 71 insertions, 0 deletions

diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c
index 0e91a3c9fdb2..318e8433527c 100644
--- a/fs/fscache/cookie.c
+++ b/fs/fscache/cookie.c
@@ -558,3 +558,74 @@ void __fscache_cookie_put(struct fscache_cookie *cookie)
 
         _leave("");
 }
+
+/*
+ * check the consistency between the netfs inode and the backing cache
+ *
+ * NOTE: it only serves no-index type
+ */
+int __fscache_check_consistency(struct fscache_cookie *cookie)
+{
+        struct fscache_operation *op;
+        struct fscache_object *object;
+        int ret;
+
+        _enter("%p,", cookie);
+
+        ASSERTCMP(cookie->def->type, ==, FSCACHE_COOKIE_TYPE_DATAFILE);
+
+        if (fscache_wait_for_deferred_lookup(cookie) < 0)
+                return -ERESTARTSYS;
+
+        if (hlist_empty(&cookie->backing_objects))
+                return 0;
+
+        op = kzalloc(sizeof(*op), GFP_NOIO | __GFP_NOMEMALLOC | __GFP_NORETRY);
+        if (!op)
+                return -ENOMEM;
+
+        fscache_operation_init(op, NULL, NULL);
+        op->flags = FSCACHE_OP_MYTHREAD |
+                (1 << FSCACHE_OP_WAITING);
+
+        spin_lock(&cookie->lock);
+
+        if (hlist_empty(&cookie->backing_objects))
+                goto inconsistent;
+        object = hlist_entry(cookie->backing_objects.first,
+                             struct fscache_object, cookie_link);
+        if (test_bit(FSCACHE_IOERROR, &object->cache->flags))
+                goto inconsistent;
+
+        op->debug_id = atomic_inc_return(&fscache_op_debug_id);
+
+        atomic_inc(&cookie->n_active);
+        if (fscache_submit_op(object, op) < 0)
+                goto submit_failed;
+
+        /* the work queue now carries its own ref on the object */
+        spin_unlock(&cookie->lock);
+
+        ret = fscache_wait_for_operation_activation(object, op,
+                                                    NULL, NULL, NULL);
+        if (ret == 0) {
+                /* ask the cache to honour the operation */
+                ret = object->cache->ops->check_consistency(op);
+                fscache_op_complete(op, false);
+        } else if (ret == -ENOBUFS) {
+                ret = 0;
+        }
+
+        fscache_put_operation(op);
+        _leave(" = %d", ret);
+        return ret;
+
+submit_failed:
+        atomic_dec(&cookie->n_active);
+inconsistent:
+        spin_unlock(&cookie->lock);
+        kfree(op);
+        _leave(" = -ESTALE");
+        return -ESTALE;
+}
+EXPORT_SYMBOL(__fscache_check_consistency);