Add notifier block to notify other subsystems about the addition or removal of block devices. Signed-off-by: Daniel Golle <daniel@xxxxxxxxxxxxxx> --- block/Kconfig | 6 +++ block/Makefile | 1 + block/blk-notify.c | 88 ++++++++++++++++++++++++++++++++++++++++++ include/linux/blkdev.h | 8 ++++ 4 files changed, 103 insertions(+) create mode 100644 block/blk-notify.c diff --git a/block/Kconfig b/block/Kconfig index 5b623b876d3b..67cd4f92378a 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 ddfd21c1a9ff..a131fa7d6b26 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 000000000000..594df7aa7be0 --- /dev/null +++ b/block/blk-notify.c @@ -0,0 +1,88 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Notifiers for addition and removal of block devices + * + * Copyright (c) 2024 Daniel Golle <daniel@xxxxxxxxxxxxxx> + */ + +#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 b2f1362c4681..8d22ba03e3e1 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -1687,4 +1687,12 @@ static inline bool bdev_can_atomic_write(struct block_device *bdev) #define DEFINE_IO_COMP_BATCH(name) struct io_comp_batch name = { } + +#ifdef CONFIG_BLOCK_NOTIFIERS +#define BLK_DEVICE_ADD 1 +#define BLK_DEVICE_REMOVE 2 +void blk_register_notify(struct notifier_block *nb); +void blk_unregister_notify(struct notifier_block *nb); +#endif + #endif /* _LINUX_BLKDEV_H */ -- 2.45.2