Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 171 insertions, 0 deletions

diff --git a/block/holder.c b/block/holder.c
new file mode 100644
index 000000000..5283bc804
--- /dev/null
+++ b/block/holder.c
@@ -0,0 +1,171 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/blkdev.h>
+#include <linux/slab.h>
+
+struct bd_holder_disk {
+	struct list_head	list;
+	struct block_device	*bdev;
+	int			refcnt;
+};
+
+static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
+						  struct gendisk *disk)
+{
+	struct bd_holder_disk *holder;
+
+	list_for_each_entry(holder, &disk->slave_bdevs, list)
+		if (holder->bdev == bdev)
+			return holder;
+	return NULL;
+}
+
+static int add_symlink(struct kobject *from, struct kobject *to)
+{
+	return sysfs_create_link(from, to, kobject_name(to));
+}
+
+static void del_symlink(struct kobject *from, struct kobject *to)
+{
+	sysfs_remove_link(from, kobject_name(to));
+}
+
+static int __link_disk_holder(struct block_device *bdev, struct gendisk *disk)
+{
+	int ret;
+
+	ret = add_symlink(disk->slave_dir, bdev_kobj(bdev));
+	if (ret)
+		return ret;
+	ret = add_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj);
+	if (ret)
+		del_symlink(disk->slave_dir, bdev_kobj(bdev));
+	return ret;
+}
+
+/**
+ * bd_link_disk_holder - create symlinks between holding disk and slave bdev
+ * @bdev: the claimed slave bdev
+ * @disk: the holding disk
+ *
+ * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
+ *
+ * This functions creates the following sysfs symlinks.
+ *
+ * - from "slaves" directory of the holder @disk to the claimed @bdev
+ * - from "holders" directory of the @bdev to the holder @disk
+ *
+ * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
+ * passed to bd_link_disk_holder(), then:
+ *
+ *   /sys/block/dm-0/slaves/sda --> /sys/block/sda
+ *   /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
+ *
+ * The caller must have claimed @bdev before calling this function and
+ * ensure that both @bdev and @disk are valid during the creation and
+ * lifetime of these symlinks.
+ *
+ * CONTEXT:
+ * Might sleep.
+ *
+ * RETURNS:
+ * 0 on success, -errno on failure.
+ */
+int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
+{
+	struct bd_holder_disk *holder;
+	int ret = 0;
+
+	mutex_lock(&disk->open_mutex);
+
+	WARN_ON_ONCE(!bdev->bd_holder);
+
+	holder = bd_find_holder_disk(bdev, disk);
+	if (holder) {
+		holder->refcnt++;
+		goto out_unlock;
+	}
+
+	holder = kzalloc(sizeof(*holder), GFP_KERNEL);
+	if (!holder) {
+		ret = -ENOMEM;
+		goto out_unlock;
+	}
+
+	INIT_LIST_HEAD(&holder->list);
+	holder->bdev = bdev;
+	holder->refcnt = 1;
+	if (disk->slave_dir) {
+		ret = __link_disk_holder(bdev, disk);
+		if (ret) {
+			kfree(holder);
+			goto out_unlock;
+		}
+	}
+
+	list_add(&holder->list, &disk->slave_bdevs);
+	/*
+	 * del_gendisk drops the initial reference to bd_holder_dir, so we need
+	 * to keep our own here to allow for cleanup past that point.
+	 */
+	kobject_get(bdev->bd_holder_dir);
+
+out_unlock:
+	mutex_unlock(&disk->open_mutex);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(bd_link_disk_holder);
+
+static void __unlink_disk_holder(struct block_device *bdev,
+		struct gendisk *disk)
+{
+	del_symlink(disk->slave_dir, bdev_kobj(bdev));
+	del_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj);
+}
+
+/**
+ * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
+ * @bdev: the calimed slave bdev
+ * @disk: the holding disk
+ *
+ * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
+ *
+ * CONTEXT:
+ * Might sleep.
+ */
+void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
+{
+	struct bd_holder_disk *holder;
+
+	mutex_lock(&disk->open_mutex);
+	holder = bd_find_holder_disk(bdev, disk);
+	if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
+		if (disk->slave_dir)
+			__unlink_disk_holder(bdev, disk);
+		kobject_put(bdev->bd_holder_dir);
+		list_del_init(&holder->list);
+		kfree(holder);
+	}
+	mutex_unlock(&disk->open_mutex);
+}
+EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
+
+int bd_register_pending_holders(struct gendisk *disk)
+{
+	struct bd_holder_disk *holder;
+	int ret;
+
+	mutex_lock(&disk->open_mutex);
+	list_for_each_entry(holder, &disk->slave_bdevs, list) {
+		ret = __link_disk_holder(holder->bdev, disk);
+		if (ret)
+			goto out_undo;
+	}
+	mutex_unlock(&disk->open_mutex);
+	return 0;
+
+out_undo:
+	list_for_each_entry_continue_reverse(holder, &disk->slave_bdevs, list)
+		__unlink_disk_holder(holder->bdev, disk);
+	mutex_unlock(&disk->open_mutex);
+	return ret;
+}