block: preparations for NVMEM provider

PATCH Superseded Daniel Golle 2 participants 11 messages Jun 26, 2024

Subsystems (3)

Device tree bindings Block layer MMC, SD and SDIO

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Daniel Golle

author

2024-06-26 02:50 UTC #0 lore raw

v3 cover block: preparations for NVMEM provider

On embedded devices using an eMMC it is common that one or more (hw/sw) partitions on the eMMC are used to store MAC addresses and Wi-Fi calibration EEPROM data.

Typically the NVMEM framework is used to have kernel drivers read and use binary data from EEPROMs, efuses, flash memory (MTD), ...

Using references to NVMEM bits in Device Tree allows the kernel to access and apply e.g. the Ethernet MAC address, which can be a requirement for userland to come up (e.g. for nfsroot).

The goal of this series is to prepare the block subsystem to allow for the implementation of an NVMEM provider similar to other types of non-volatile storage, so the same approach already used for EEPROMs, MTD (raw flashes) and UBI-managed NAND can also be used for devices storing those bits on an eMMC.

Define a device tree schema for block devices and partitions on them, which (similar to how it now works also for UBI volumes) can be matched by one or more properties.

Also add a simple notification API for other subsystems to be notified about additions and removals of block devices, which is going to be used by the block-backed NVMEM provider.

Overall, this enables uniform handling across practially all flash storage types used for this purpose (MTD, UBI, and soon also MMC or and in future maybe also other block devices).
---
Changes since v2 sent on May 30th 2024 [1] addressing comments from Hauke Mehrtens (https://patchwork.kernel.org/comment/25892133/)
- Check length of UUID and PARTNAME.
- Remove forgotten fallback to get 'partitions' subnode from parent. It is no longer needed and was a left over from earlier development.
- Split series into 3 parts, one for each affected subsystem. This is the first part covering only the changes needed in the block subsystem. The second part adds the actual nvmem provider to drivers/nvmem/, the third part is going to make use of it for MMC block devices and cover changes in drivers/mmc.

Changes since v1 sent on March 21st 2024 [2]:
- introduce notifications for block device addition and removal for in-kernel users. This allows the nvmem driver to be built as a module and avoids using class_interface and block subsystem internals as suggested in https://patchwork.kernel.org/comment/25771998/ and
https://patchwork.kernel.org/comment/25770441/

This series has previously been submitted as RFC on July 19th 2023[3] and most of the basic idea did not change since. Another round of RFC was submitted on March 5th 2024[4].

[1]: https://patchwork.kernel.org/project/linux-block/list/?series=857192
[2]: https://patchwork.kernel.org/project/linux-block/list/?series=837150&archive=both
[3]: https://patchwork.kernel.org/project/linux-block/list/?series=767565
[4]: https://patchwork.kernel.org/project/linux-block/list/?series=832705

Daniel Golle (4):
dt-bindings: block: add basic bindings for block devices
block: partitions: populate fwnode
block: add support for notifications
block: add new genhd flag GENHD_FL_NVMEM

 .../bindings/block/block-device.yaml          | 22 +++++
 .../devicetree/bindings/block/partition.yaml  | 51 +++++++++++
 .../devicetree/bindings/block/partitions.yaml | 20 +++++
 block/Kconfig                                 |  6 ++
 block/Makefile                                |  1 +
 block/blk-notify.c                            | 88 +++++++++++++++++++
 block/partitions/core.c                       | 40 +++++++++
 include/linux/blkdev.h                        | 10 +++
 8 files changed, 238 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/block/block-device.yaml
 create mode 100644 Documentation/devicetree/bindings/block/partition.yaml
 create mode 100644 Documentation/devicetree/bindings/block/partitions.yaml
 create mode 100644 block/blk-notify.c

Signature · 1 line

2.45.2

Daniel Golle

author

2024-06-26 02:50 UTC #1 lore raw

PATCH v3 1/4 dt-bindings: block: add basic bindings for block devices

Add bindings for block devices which are used to allow referencing nvmem bits on them.

Signed-off-by Daniel Golle <[email protected]>

---
 .../bindings/block/block-device.yaml          | 22 ++++++++
 .../devicetree/bindings/block/partition.yaml  | 51 +++++++++++++++++++
 .../devicetree/bindings/block/partitions.yaml | 20 ++++++++
 3 files changed, 93 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/block/block-device.yaml
 create mode 100644 Documentation/devicetree/bindings/block/partition.yaml
 create mode 100644 Documentation/devicetree/bindings/block/partitions.yaml

Documentation/devicetree/bindings/block/block-device.yaml new file +22 -0

new file mode 100644
index 000000000000..c83ea525650b
@@ -0,0 +1,22 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/block/block-device.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: block storage device
+
+description: |
+  This binding is generic and describes a block-oriented storage device.
+
+maintainers:
+  - Daniel Golle <[email protected]>
+
+properties:
+  partitions:
+    $ref: /schemas/block/partitions.yaml
+
+  nvmem-layout:
+    $ref: /schemas/nvmem/layouts/nvmem-layout.yaml#
+
+unevaluatedProperties: false

Documentation/devicetree/bindings/block/partition.yaml new file +51 -0

51 lines not on this page · raw message

Documentation/devicetree/bindings/block/partitions.yaml new file +20 -0

new file mode 100644
index 000000000000..fd84c3ba8493
@@ -0,0 +1,20 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/block/partitions.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Partitions on block devices
+
+description: |
+  This binding is generic and describes the content of the partitions container
+  node.
+
+maintainers:
+  - Daniel Golle <[email protected]>
+
+patternProperties:
+  "^block-partition-.+$":
+    $ref: partition.yaml
+
+unevaluatedProperties: false

Signature · 1 line

2.45.2

Daniel Golle

author

2024-06-26 02:51 UTC #2 lore raw

PATCH v3 2/4 block: partitions: populate fwnode

In reply to Daniel Golle

Let block partitions to be represented by a firmware node and hence allow them to being referenced e.g. for use with blk-nvmem.

Signed-off-by Daniel Golle <[email protected]>

---
 block/partitions/core.c | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

block/partitions/core.c +40 -0

index ab76e64f0f6c..f88829e254e6 100644
@@ -10,6 +10,8 @@
 #include <linux/ctype.h>
 #include <linux/vmalloc.h>
 #include <linux/raid/detect.h>
+#include <linux/property.h>
+
 #include "check.h"
 
 static int (*const check_part[])(struct parsed_partitions *) = {

@@ -281,6 +283,42 @@ static ssize_t whole_disk_show(struct device *dev,
 }
 static const DEVICE_ATTR(whole_disk, 0444, whole_disk_show, NULL);
 
+static struct fwnode_handle *find_partition_fwnode(struct block_device *bdev)
+{
+	struct fwnode_handle *fw_parts, *fw_part;
+	struct device *ddev = disk_to_dev(bdev->bd_disk);
+	const char *partname, *uuid;
+	u32 partno;
+
+	fw_parts = device_get_named_child_node(ddev, "partitions");
+	if (!fw_parts)
+		fw_parts = device_get_named_child_node(ddev->parent, "partitions");
+
+	if (!fw_parts)
+		return NULL;
+
+	fwnode_for_each_child_node(fw_parts, fw_part) {
+		if (!fwnode_property_read_string(fw_part, "uuid", &uuid) &&
+		    (!bdev->bd_meta_info || strlen(uuid) > PARTITION_META_INFO_UUIDLTH ||
+		     strncmp(uuid, bdev->bd_meta_info->uuid, PARTITION_META_INFO_UUIDLTH)))
+			continue;
+
+		if (!fwnode_property_read_string(fw_part, "partname", &partname) &&
+		    (!bdev->bd_meta_info || strlen(uuid) > PARTITION_META_INFO_VOLNAMELTH ||
+		     strncmp(partname, bdev->bd_meta_info->volname,
+			     PARTITION_META_INFO_VOLNAMELTH)))
+			continue;
+
+		if (!fwnode_property_read_u32(fw_part, "partno", &partno) &&
+		    bdev_partno(bdev) != partno)
+			continue;
+
+		return fw_part;
+	}
+
+	return NULL;
+}
+
 /*
  * Must be called either with open_mutex held, before a disk can be opened or
  * after all disk users are gone.

@@ -355,6 +393,8 @@ static struct block_device *add_partition(struct gendisk *disk, int partno,
 			goto out_put;
 	}
 
+	device_set_node(pdev, find_partition_fwnode(bdev));
+
 	/* delay uevent until 'holders' subdir is created */
 	dev_set_uevent_suppress(pdev, 1);
 	err = device_add(pdev);

Signature · 1 line

2.45.2

Jens Axboe

maintainer

2024-06-26 19:43 UTC #3 lore raw

Re: [PATCH v3 2/4] block: partitions: populate fwnode

Quoted 20 lines · Daniel Golle

block/partitions/core.c +5 -0

index ab76e64f0f6c..f88829e254e6 100644
@@ -10,6 +10,8 @@
 #include <linux/ctype.h>
 #include <linux/vmalloc.h>
 #include <linux/raid/detect.h>
+#include <linux/property.h>
+
 #include "check.h"
 
 static int (*const check_part[])(struct parsed_partitions *) = {

@@ -281,6 +283,42 @@ static ssize_t whole_disk_show(struct device *dev,
 }
 static const DEVICE_ATTR(whole_disk, 0444, whole_disk_show, NULL);
 
+static struct fwnode_handle *find_partition_fwnode(struct block_device *bdev)
+{
+	struct fwnode_handle *fw_parts, *fw_part;

block/partitions/core.c static ssize_t whole_disk_show(struct device *dev, · line 298

Quoted 10 lines

block/partitions/core.c +10 -0

+	struct device *ddev = disk_to_dev(bdev->bd_disk);
+	const char *partname, *uuid;
+	u32 partno;
+
+	fw_parts = device_get_named_child_node(ddev, "partitions");
+	if (!fw_parts)
+		fw_parts = device_get_named_child_node(ddev->parent, "partitions");
+
+	if (!fw_parts)
+		return NULL;

That last if check should to inside the previous one.

block/partitions/core.c static ssize_t whole_disk_show(struct device *dev, · line 310

Quoted 11 lines

block/partitions/core.c +11 -0

+	fwnode_for_each_child_node(fw_parts, fw_part) {
+		if (!fwnode_property_read_string(fw_part, "uuid", &uuid) &&
+		    (!bdev->bd_meta_info || strlen(uuid) > PARTITION_META_INFO_UUIDLTH ||
+		     strncmp(uuid, bdev->bd_meta_info->uuid, PARTITION_META_INFO_UUIDLTH)))
+			continue;
+
+		if (!fwnode_property_read_string(fw_part, "partname", &partname) &&
+		    (!bdev->bd_meta_info || strlen(uuid) > PARTITION_META_INFO_VOLNAMELTH ||
+		     strncmp(partname, bdev->bd_meta_info->volname,
+			     PARTITION_META_INFO_VOLNAMELTH)))
+			continue;

This is pretty hard to make sense of...

Signature · 1 line

Jens Axboe

Daniel Golle

author

2024-06-26 19:58 UTC #4 lore raw

Re: [PATCH v3 2/4] block: partitions: populate fwnode

Quoted 18 lines · Jens Axboe

Quoted 17 lines · Daniel Golle

block/partitions/core.c +2 -0

index ab76e64f0f6c..f88829e254e6 100644
@@ -10,6 +10,8 @@
 #include <linux/ctype.h>
 #include <linux/vmalloc.h>
 #include <linux/raid/detect.h>
+#include <linux/property.h>
+
 #include "check.h"
 
 static int (*const check_part[])(struct parsed_partitions *) = {

@@ -281,6 +283,42 @@ static ssize_t whole_disk_show(struct device *dev,
 }
 static const DEVICE_ATTR(whole_disk, 0444, whole_disk_show, NULL);

Quoted 15 lines

block/partitions/core.c static ssize_t whole_disk_show(struct device *dev, · line 298

Quoted 13 lines

block/partitions/core.c +13 -0

+static struct fwnode_handle *find_partition_fwnode(struct block_device *bdev)
+{
+	struct fwnode_handle *fw_parts, *fw_part;
+	struct device *ddev = disk_to_dev(bdev->bd_disk);
+	const char *partname, *uuid;
+	u32 partno;
+
+	fw_parts = device_get_named_child_node(ddev, "partitions");
+	if (!fw_parts)
+		fw_parts = device_get_named_child_node(ddev->parent, "partitions");
+
+	if (!fw_parts)
+		return NULL;

That last if check should to inside the previous one.

Actually the previous one should have been removed entirely. I somehow forgot to 'git add' that change.

Quoted 14 lines

block/partitions/core.c static ssize_t whole_disk_show(struct device *dev, · line 310

Quoted 12 lines

block/partitions/core.c +11 -0

+	fwnode_for_each_child_node(fw_parts, fw_part) {
+		if (!fwnode_property_read_string(fw_part, "uuid", &uuid) &&
+		    (!bdev->bd_meta_info || strlen(uuid) > PARTITION_META_INFO_UUIDLTH ||
+		     strncmp(uuid, bdev->bd_meta_info->uuid, PARTITION_META_INFO_UUIDLTH)))
+			continue;
+
+		if (!fwnode_property_read_string(fw_part, "partname", &partname) &&
+		    (!bdev->bd_meta_info || strlen(uuid) > PARTITION_META_INFO_VOLNAMELTH ||
+		     strncmp(partname, bdev->bd_meta_info->volname,
+			     PARTITION_META_INFO_VOLNAMELTH)))
+			continue;

This is pretty hard to make sense of...

I'll add comments explaining it. Or should I use another syntax, e.g. several nested if-clauses, instead?

Jens Axboe

maintainer

2024-06-26 20:09 UTC #5 lore raw

Re: [PATCH v3 2/4] block: partitions: populate fwnode

Quoted 53 lines · Daniel Golle

Quoted 18 lines · Jens Axboe

Quoted 17 lines · Daniel Golle

block/partitions/core.c +2 -0

index ab76e64f0f6c..f88829e254e6 100644
@@ -10,6 +10,8 @@
 #include <linux/ctype.h>
 #include <linux/vmalloc.h>
 #include <linux/raid/detect.h>
+#include <linux/property.h>
+
 #include "check.h"
 
 static int (*const check_part[])(struct parsed_partitions *) = {

@@ -281,6 +283,42 @@ static ssize_t whole_disk_show(struct device *dev,
 }
 static const DEVICE_ATTR(whole_disk, 0444, whole_disk_show, NULL);

Quoted 15 lines

block/partitions/core.c static ssize_t whole_disk_show(struct device *dev, · line 298

Quoted 13 lines

block/partitions/core.c +13 -0

+static struct fwnode_handle *find_partition_fwnode(struct block_device *bdev)
+{
+	struct fwnode_handle *fw_parts, *fw_part;
+	struct device *ddev = disk_to_dev(bdev->bd_disk);
+	const char *partname, *uuid;
+	u32 partno;
+
+	fw_parts = device_get_named_child_node(ddev, "partitions");
+	if (!fw_parts)
+		fw_parts = device_get_named_child_node(ddev->parent, "partitions");
+
+	if (!fw_parts)
+		return NULL;

That last if check should to inside the previous one.

Actually the previous one should have been removed entirely. I somehow forgot to 'git add' that change.

Quoted 14 lines

block/partitions/core.c static ssize_t whole_disk_show(struct device *dev, · line 310

Quoted 12 lines

block/partitions/core.c +11 -0

+	fwnode_for_each_child_node(fw_parts, fw_part) {
+		if (!fwnode_property_read_string(fw_part, "uuid", &uuid) &&
+		    (!bdev->bd_meta_info || strlen(uuid) > PARTITION_META_INFO_UUIDLTH ||
+		     strncmp(uuid, bdev->bd_meta_info->uuid, PARTITION_META_INFO_UUIDLTH)))
+			continue;
+
+		if (!fwnode_property_read_string(fw_part, "partname", &partname) &&
+		    (!bdev->bd_meta_info || strlen(uuid) > PARTITION_META_INFO_VOLNAMELTH ||
+		     strncmp(partname, bdev->bd_meta_info->volname,
+			     PARTITION_META_INFO_VOLNAMELTH)))
+			continue;

This is pretty hard to make sense of...

Quoted 2 lines

I'll add comments explaining it. Or should I use another syntax, e.g. several nested if-clauses, instead?

Maybe some kind of helpers for these instead, with comments? Nobody can read the above.

Signature · 1 line

Jens Axboe

Daniel Golle

author

2024-06-26 02:51 UTC #6 lore raw

PATCH v3 3/4 block: add support for notifications

In reply to Daniel Golle

Add notifier block to notify other subsystems about the addition or removal of block devices.

Signed-off-by Daniel Golle <[email protected]>

---
 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

block/Kconfig +6 -0

index 5b623b876d3b..67cd4f92378a 100644
@@ -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

block/Makefile +1 -0

index ddfd21c1a9ff..a131fa7d6b26 100644
@@ -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

block/blk-notify.c new file +88 -0

88 lines not on this page · raw message

include/linux/blkdev.h +8 -0

index b2f1362c4681..8d22ba03e3e1 100644
@@ -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 */

Signature · 1 line

2.45.2

Jens Axboe

maintainer

2024-06-26 19:46 UTC #7 lore raw

Re: [PATCH v3 3/4] block: add support for notifications

Quoted 6 lines · Daniel Golle

block/blk-notify.c new file +6 -0

+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)

block/blk-notify.c line 60

Quoted 10 lines

block/blk-notify.c new file +10 -0

+		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;
+}

Nit: redundant newline.

include/linux/blkdev.h static inline bool bdev_can_atomic_write(struct block_device *bdev) · line 1691

Quoted 11 lines

block/blk-notify.c new file +1 -0

+device_initcall(blk_notifications_init);

include/linux/blkdev.h +2 -0

index b2f1362c4681..8d22ba03e3e1 100644
@@ -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

#if defined(CONFIG_BLOCK_NOTIFIERS)

include/linux/blkdev.h static inline bool bdev_can_atomic_write(struct block_device *bdev) · line 1696

Quoted 5 lines

include/linux/blkdev.h +5 -0

+#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

Surely these helpers should have a !CONFIG_BLOCK_NOTIFIERS failure case definition? Either that, or dummies. As it stands, any caller would need to check if it's enabled or not.

Signature · 1 line

Jens Axboe

Daniel Golle

author

2024-06-26 19:56 UTC #8 lore raw

Re: [PATCH v3 3/4] block: add support for notifications

Hi Jens,

thanks a lot for the review!

Quoted 11 lines · Jens Axboe

Quoted 10 lines · Daniel Golle

block/blk-notify.c new file +10 -0

+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);

Quoted 8 lines

block/blk-notify.c line 60
Quoted 6 lines
block/blk-notify.c new file +6 -0
+	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;
+}
Nit: redundant newline.

I'll remove the newline before the 'return' statement then, right?

Quoted 15 lines

include/linux/blkdev.h static inline bool bdev_can_atomic_write(struct block_device *bdev) · line 1691
Quoted 12 lines
block/blk-notify.c new file +1 -0
+device_initcall(blk_notifications_init);
include/linux/blkdev.h +2 -0
index b2f1362c4681..8d22ba03e3e1 100644
@@ -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
#if defined(CONFIG_BLOCK_NOTIFIERS)

Quoted 9 lines

include/linux/blkdev.h static inline bool bdev_can_atomic_write(struct block_device *bdev) · line 1696
Quoted 5 lines
include/linux/blkdev.h +5 -0
+#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
Surely these helpers should have a !CONFIG_BLOCK_NOTIFIERS failure case definition? Either that, or dummies. As it stands, any caller would need to check if it's enabled or not.

Makes sense. I'll add dummies to the header and always define the macros for notification types.

Note that what I'm planning to do is to have the block nvmem provider select CONFIG_BLOCK_NOTIFIERS in Kconfig, as without that it simply won't work at all.

Cheers

Daniel

Jens Axboe

maintainer

2024-06-26 20:23 UTC #9 lore raw

Re: [PATCH v3 3/4] block: add support for notifications

Quoted 25 lines · Daniel Golle

Hi Jens,
thanks a lot for the review!
Quoted 11 lines · Jens Axboe
Quoted 10 lines · Daniel Golle
block/blk-notify.c new file +10 -0
+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);
Quoted 8 lines
block/blk-notify.c line 60
Quoted 6 lines
block/blk-notify.c new file +6 -0
+	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;
+}
Nit: redundant newline.

Quoted 1 line

I'll remove the newline before the 'return' statement then, right?

Yup

Quoted 24 lines

Quoted 14 lines
include/linux/blkdev.h static inline bool bdev_can_atomic_write(struct block_device *bdev) · line 1691
Quoted 11 lines
block/blk-notify.c new file +1 -0
+device_initcall(blk_notifications_init);
include/linux/blkdev.h +2 -0
index b2f1362c4681..8d22ba03e3e1 100644
@@ -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
#if defined(CONFIG_BLOCK_NOTIFIERS)
Quoted 9 lines
include/linux/blkdev.h static inline bool bdev_can_atomic_write(struct block_device *bdev) · line 1696
Quoted 5 lines
include/linux/blkdev.h +5 -0
+#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
Surely these helpers should have a !CONFIG_BLOCK_NOTIFIERS failure case definition? Either that, or dummies. As it stands, any caller would need to check if it's enabled or not.

Quoted 2 lines

Makes sense. I'll add dummies to the header and always define the macros for notification types.

Exactly

Quoted 3 lines

Note that what I'm planning to do is to have the block nvmem provider select CONFIG_BLOCK_NOTIFIERS in Kconfig, as without that it simply won't work at all.

Right, but then someone else uses them for something else, and then we'll need it anyway.

Signature · 1 line

Jens Axboe

Daniel Golle

author

2024-06-26 02:51 UTC #10 lore raw

PATCH v3 4/4 block: add new genhd flag GENHD_FL_NVMEM

In reply to Daniel Golle

Add new flag to destinguish block devices which may act as an NVMEM provider.

Signed-off-by Daniel Golle <[email protected]>

---
 include/linux/blkdev.h | 2 ++
 1 file changed, 2 insertions(+)

include/linux/blkdev.h +2 -0

index 8d22ba03e3e1..6c74c69d2ee1 100644
@@ -81,11 +81,13 @@ struct partition_meta_info {
  * ``GENHD_FL_NO_PART``: partition support is disabled.  The kernel will not
  * scan for partitions from add_disk, and users can't add partitions manually.
  *
+ * ``GENHD_FL_NVMEM``: the block device should be considered as NVMEM provider.
  */
 enum {
 	GENHD_FL_REMOVABLE			= 1 << 0,
 	GENHD_FL_HIDDEN				= 1 << 1,
 	GENHD_FL_NO_PART			= 1 << 2,
+	GENHD_FL_NVMEM				= 1 << 3,
 };
 
 enum {

Signature · 1 line

2.45.2