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Allow a wider audience to test this pending series. Use about to be submitted v3 which factors out block notification support. Apart from dropping the no longer needed (and problematic) fallback for for the 'partitions' node being present at the device parent there are no intended functional changes. As opening a block device as file is not supported yet in Kernel v6.6, use the previous method as backporting seems a bit too involving. Fixes: #15642 Signed-off-by: Daniel Golle <daniel@makrotopia.org>
146 lines
4.0 KiB
Diff
146 lines
4.0 KiB
Diff
From e07ace307ce598847074a096f408bec0e3a392ed Mon Sep 17 00:00:00 2001
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From: Daniel Golle <daniel@makrotopia.org>
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Date: Thu, 30 May 2024 03:14:34 +0100
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Subject: [PATCH 3/9] block: add support for notifications
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Add notifier block to notify other subsystems about the addition or
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removal of block devices.
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Signed-off-by: Daniel Golle <daniel@makrotopia.org>
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---
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block/Kconfig | 6 +++
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block/Makefile | 1 +
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block/blk-notify.c | 88 ++++++++++++++++++++++++++++++++++++++++++
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include/linux/blkdev.h | 8 ++++
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4 files changed, 103 insertions(+)
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create mode 100644 block/blk-notify.c
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--- a/block/Kconfig
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+++ b/block/Kconfig
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@@ -208,6 +208,12 @@ config BLK_INLINE_ENCRYPTION_FALLBACK
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by falling back to the kernel crypto API when inline
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encryption hardware is not present.
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+config BLOCK_NOTIFIERS
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+ bool "Enable support for notifications in block layer"
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+ help
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+ Enable this option to provide notifiers for other subsystems
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+ upon addition or removal of block devices.
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+
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source "block/partitions/Kconfig"
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config BLK_MQ_PCI
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--- a/block/Makefile
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+++ b/block/Makefile
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@@ -40,3 +40,4 @@ obj-$(CONFIG_BLK_INLINE_ENCRYPTION) += b
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blk-crypto-sysfs.o
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obj-$(CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK) += blk-crypto-fallback.o
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obj-$(CONFIG_BLOCK_HOLDER_DEPRECATED) += holder.o
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+obj-$(CONFIG_BLOCK_NOTIFIERS) += blk-notify.o
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--- /dev/null
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+++ b/block/blk-notify.c
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@@ -0,0 +1,88 @@
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+// SPDX-License-Identifier: GPL-2.0-or-later
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+/*
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+ * Notifiers for addition and removal of block devices
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+ *
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+ * Copyright (c) 2024 Daniel Golle <daniel@makrotopia.org>
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+ */
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+
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+#include <linux/list.h>
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+#include <linux/mutex.h>
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+#include <linux/notifier.h>
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+
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+#include "blk.h"
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+
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+struct blk_device_list {
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+ struct device *dev;
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+ struct list_head list;
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+};
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+
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+static RAW_NOTIFIER_HEAD(blk_notifier_list);
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+static DEFINE_MUTEX(blk_notifier_lock);
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+static LIST_HEAD(blk_devices);
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+
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+void blk_register_notify(struct notifier_block *nb)
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+{
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+ struct blk_device_list *existing_blkdev;
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+
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+ mutex_lock(&blk_notifier_lock);
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+ raw_notifier_chain_register(&blk_notifier_list, nb);
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+
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+ list_for_each_entry(existing_blkdev, &blk_devices, list)
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+ nb->notifier_call(nb, BLK_DEVICE_ADD, existing_blkdev->dev);
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+
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+ mutex_unlock(&blk_notifier_lock);
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+}
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+EXPORT_SYMBOL_GPL(blk_register_notify);
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+
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+void blk_unregister_notify(struct notifier_block *nb)
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+{
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+ mutex_lock(&blk_notifier_lock);
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+ raw_notifier_chain_unregister(&blk_notifier_list, nb);
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+ mutex_unlock(&blk_notifier_lock);
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+}
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+EXPORT_SYMBOL_GPL(blk_unregister_notify);
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+
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+static int blk_call_notifier_add(struct device *dev)
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+{
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+ struct blk_device_list *new_blkdev;
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+
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+ new_blkdev = kmalloc(sizeof(*new_blkdev), GFP_KERNEL);
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+ if (!new_blkdev)
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+ return -ENOMEM;
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+
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+ new_blkdev->dev = dev;
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+ mutex_lock(&blk_notifier_lock);
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+ list_add_tail(&new_blkdev->list, &blk_devices);
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+ raw_notifier_call_chain(&blk_notifier_list, BLK_DEVICE_ADD, dev);
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+ mutex_unlock(&blk_notifier_lock);
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+
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+ return 0;
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+}
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+
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+static void blk_call_notifier_remove(struct device *dev)
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+{
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+ struct blk_device_list *old_blkdev, *tmp;
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+
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+ mutex_lock(&blk_notifier_lock);
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+ list_for_each_entry_safe(old_blkdev, tmp, &blk_devices, list) {
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+ if (old_blkdev->dev != dev)
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+ continue;
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+
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+ list_del(&old_blkdev->list);
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+ kfree(old_blkdev);
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+ }
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+ raw_notifier_call_chain(&blk_notifier_list, BLK_DEVICE_REMOVE, dev);
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+ mutex_unlock(&blk_notifier_lock);
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+}
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+
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+static struct class_interface blk_notifications_bus_interface __refdata = {
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+ .class = &block_class,
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+ .add_dev = &blk_call_notifier_add,
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+ .remove_dev = &blk_call_notifier_remove,
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+};
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+
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+static int __init blk_notifications_init(void)
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+{
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+ return class_interface_register(&blk_notifications_bus_interface);
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+}
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+device_initcall(blk_notifications_init);
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--- a/include/linux/blkdev.h
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+++ b/include/linux/blkdev.h
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@@ -1564,4 +1564,12 @@ struct io_comp_batch {
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#define DEFINE_IO_COMP_BATCH(name) struct io_comp_batch name = { }
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+
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+#ifdef CONFIG_BLOCK_NOTIFIERS
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+#define BLK_DEVICE_ADD 1
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+#define BLK_DEVICE_REMOVE 2
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+void blk_register_notify(struct notifier_block *nb);
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+void blk_unregister_notify(struct notifier_block *nb);
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+#endif
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+
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#endif /* _LINUX_BLKDEV_H */
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