Merge tag 'block-6.15-20250522' of git://git.kernel.dk/linux

Pull block fixes from Jens Axboe:

 - Fix for a regression with setting up loop on a file system
   without ->write_iter()

 - Fix for an nvme sysfs regression

* tag 'block-6.15-20250522' of git://git.kernel.dk/linux:
  nvme: avoid creating multipath sysfs group under namespace path devices
  loop: don't require ->write_iter for writable files in loop_configure

Author: torvalds

drivers/block/loop.c

@@ -979,9 +979,6 @@ static int loop_configure(struct loop_device *lo, blk_mode_t mode,
 	if (!file)
 		return -EBADF;
 
-	if ((mode & BLK_OPEN_WRITE) && !file->f_op->write_iter)
-		return -EINVAL;
-
 	error = loop_check_backing_file(file);
 	if (error)
 		return error;

drivers/nvme/host/sysfs.c

@@ -306,13 +306,41 @@ static const struct attribute_group nvme_ns_attr_group = {
 };
 
 #ifdef CONFIG_NVME_MULTIPATH
+/*
+ * NOTE: The dummy attribute does not appear in sysfs. It exists solely to allow
+ * control over the visibility of the multipath sysfs node. Without at least one
+ * attribute defined in nvme_ns_mpath_attrs[], the sysfs implementation does not
+ * invoke the multipath_sysfs_group_visible() method. As a result, we would not
+ * be able to control the visibility of the multipath sysfs node.
+ */
+static struct attribute dummy_attr = {
+	.name = "dummy",
+};
+
 static struct attribute *nvme_ns_mpath_attrs[] = {
+	&dummy_attr,
 	NULL,
 };
 
+static bool multipath_sysfs_group_visible(struct kobject *kobj)
+{
+	struct device *dev = container_of(kobj, struct device, kobj);
+
+	return nvme_disk_is_ns_head(dev_to_disk(dev));
+}
+
+static bool multipath_sysfs_attr_visible(struct kobject *kobj,
+		struct attribute *attr, int n)
+{
+	return false;
+}
+
+DEFINE_SYSFS_GROUP_VISIBLE(multipath_sysfs)
+
 const struct attribute_group nvme_ns_mpath_attr_group = {
 	.name           = "multipath",
 	.attrs		= nvme_ns_mpath_attrs,
+	.is_visible     = SYSFS_GROUP_VISIBLE(multipath_sysfs),
 };
 #endif