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Message-ID: <ca0022886e8f211a323a716653a1396a3bc91653.1722365899.git.daniel@makrotopia.org>
Date: Tue, 30 Jul 2024 20:26:42 +0100
From: Daniel Golle <daniel@...rotopia.org>
To: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>, Jens Axboe <axboe@...nel.dk>,
Daniel Golle <daniel@...rotopia.org>,
Christian Brauner <brauner@...nel.org>,
Al Viro <viro@...iv.linux.org.uk>,
Li Lingfeng <lilingfeng3@...wei.com>,
Ming Lei <ming.lei@...hat.com>,
Christian Heusel <christian@...sel.eu>,
Rafał Miłecki <rafal@...ecki.pl>,
Felix Fietkau <nbd@....name>, John Crispin <john@...ozen.org>,
Chad Monroe <chad.monroe@...ran.com>,
Yangyu Chen <cyy@...self.name>,
Tianling Shen <cnsztl@...ortalwrt.org>,
Chuanhong Guo <gch981213@...il.com>,
Chen Minqiang <ptpt52@...il.com>, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-block@...r.kernel.org
Subject: [PATCH v5 3/4] block: add support for notifications
Add notifier block to notify other subsystems about the addition or
removal of block devices.
Signed-off-by: Daniel Golle <daniel@...rotopia.org>
---
block/Kconfig | 6 +++
block/Makefile | 1 +
block/blk-notify.c | 87 ++++++++++++++++++++++++++++++++++++++++++
include/linux/blkdev.h | 11 ++++++
4 files changed, 105 insertions(+)
create mode 100644 block/blk-notify.c
diff --git a/block/Kconfig b/block/Kconfig
index 5b623b876d3b4..67cd4f92378af 100644
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -209,6 +209,12 @@ config BLK_INLINE_ENCRYPTION_FALLBACK
by falling back to the kernel crypto API when inline
encryption hardware is not present.
+config BLOCK_NOTIFIERS
+ bool "Enable support for notifications in block layer"
+ help
+ Enable this option to provide notifiers for other subsystems
+ upon addition or removal of block devices.
+
source "block/partitions/Kconfig"
config BLK_MQ_PCI
diff --git a/block/Makefile b/block/Makefile
index ddfd21c1a9ffc..a131fa7d6b26e 100644
--- a/block/Makefile
+++ b/block/Makefile
@@ -38,3 +38,4 @@ obj-$(CONFIG_BLK_INLINE_ENCRYPTION) += blk-crypto.o blk-crypto-profile.o \
blk-crypto-sysfs.o
obj-$(CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK) += blk-crypto-fallback.o
obj-$(CONFIG_BLOCK_HOLDER_DEPRECATED) += holder.o
+obj-$(CONFIG_BLOCK_NOTIFIERS) += blk-notify.o
diff --git a/block/blk-notify.c b/block/blk-notify.c
new file mode 100644
index 0000000000000..fd727288ea19a
--- /dev/null
+++ b/block/blk-notify.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Notifiers for addition and removal of block devices
+ *
+ * Copyright (c) 2024 Daniel Golle <daniel@...rotopia.org>
+ */
+
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/notifier.h>
+
+#include "blk.h"
+
+struct blk_device_list {
+ struct device *dev;
+ struct list_head list;
+};
+
+static RAW_NOTIFIER_HEAD(blk_notifier_list);
+static DEFINE_MUTEX(blk_notifier_lock);
+static LIST_HEAD(blk_devices);
+
+void blk_register_notify(struct notifier_block *nb)
+{
+ struct blk_device_list *existing_blkdev;
+
+ mutex_lock(&blk_notifier_lock);
+ raw_notifier_chain_register(&blk_notifier_list, nb);
+
+ list_for_each_entry(existing_blkdev, &blk_devices, list)
+ nb->notifier_call(nb, BLK_DEVICE_ADD, existing_blkdev->dev);
+
+ mutex_unlock(&blk_notifier_lock);
+}
+EXPORT_SYMBOL_GPL(blk_register_notify);
+
+void blk_unregister_notify(struct notifier_block *nb)
+{
+ mutex_lock(&blk_notifier_lock);
+ raw_notifier_chain_unregister(&blk_notifier_list, nb);
+ mutex_unlock(&blk_notifier_lock);
+}
+EXPORT_SYMBOL_GPL(blk_unregister_notify);
+
+static int blk_call_notifier_add(struct device *dev)
+{
+ struct blk_device_list *new_blkdev;
+
+ new_blkdev = kmalloc(sizeof(*new_blkdev), GFP_KERNEL);
+ if (!new_blkdev)
+ return -ENOMEM;
+
+ new_blkdev->dev = dev;
+ mutex_lock(&blk_notifier_lock);
+ list_add_tail(&new_blkdev->list, &blk_devices);
+ raw_notifier_call_chain(&blk_notifier_list, BLK_DEVICE_ADD, dev);
+ mutex_unlock(&blk_notifier_lock);
+ return 0;
+}
+
+static void blk_call_notifier_remove(struct device *dev)
+{
+ struct blk_device_list *old_blkdev, *tmp;
+
+ mutex_lock(&blk_notifier_lock);
+ list_for_each_entry_safe(old_blkdev, tmp, &blk_devices, list) {
+ if (old_blkdev->dev != dev)
+ continue;
+
+ list_del(&old_blkdev->list);
+ kfree(old_blkdev);
+ }
+ raw_notifier_call_chain(&blk_notifier_list, BLK_DEVICE_REMOVE, dev);
+ mutex_unlock(&blk_notifier_lock);
+}
+
+static struct class_interface blk_notifications_bus_interface __refdata = {
+ .class = &block_class,
+ .add_dev = &blk_call_notifier_add,
+ .remove_dev = &blk_call_notifier_remove,
+};
+
+static int __init blk_notifications_init(void)
+{
+ return class_interface_register(&blk_notifications_bus_interface);
+}
+device_initcall(blk_notifications_init);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index e85ec73a07d57..2f871158d2860 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1682,4 +1682,15 @@ static inline bool bdev_can_atomic_write(struct block_device *bdev)
#define DEFINE_IO_COMP_BATCH(name) struct io_comp_batch name = { }
+
+#define BLK_DEVICE_ADD 1
+#define BLK_DEVICE_REMOVE 2
+#if defined(CONFIG_BLOCK_NOTIFIERS)
+void blk_register_notify(struct notifier_block *nb);
+void blk_unregister_notify(struct notifier_block *nb);
+#else
+static inline void blk_register_notify(struct notifier_block *nb) { };
+static inline void blk_unregister_notify(struct notifier_block *nb) { };
+#endif
+
#endif /* _LINUX_BLKDEV_H */
--
2.45.2
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