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SubjectRe: [resend v1 0/5] Add support for block disk resize notification
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On 1/2/20 3:53 PM, Balbir Singh wrote:
> Allow block/genhd to notify user space about disk size changes
> using a new helper disk_set_capacity(), which is a wrapper on top
> of set_capacity(). disk_set_capacity() will only notify if
> the current capacity or the target capacity is not zero.
>

set_capacity_and_notify() may be a more straightforward name.

> Background:
>
> As a part of a patch to allow sending the RESIZE event on disk capacity
> change, Christoph (hch@lst.de) requested that the patch be made generic
> and the hacks for virtio block and xen block devices be removed and
> merged via a generic helper.
>
> This series consists of 5 changes. The first one adds the basic
> support for changing the size and notifying. The follow up patches
> are per block subsystem changes. Other block drivers can add their
> changes as necessary on top of this series.
>
> Testing:
> 1. I did some basic testing with an NVME device, by resizing it in
> the backend and ensured that udevd received the event.
>
> NOTE: After these changes, the notification might happen before
> revalidate disk, where as it occured later before.
>

It's better not to change original behavior.
How about something like:

+void set_capacity_and_notify(struct gendisk *disk, sector_t size, bool revalidate)
{
sector_t capacity = get_capacity(disk);

set_capacity(disk, size);

+ if (revalidate)
+ revalidate_disk(disk);
if (capacity != 0 && size != 0) {
char *envp[] = { "RESIZE=1", NULL };

kobject_uevent_env(&disk_to_dev(disk)->kobj, KOBJ_CHANGE, envp);
}
}

> Balbir Singh (5):
> block/genhd: Notify udev about capacity change
> drivers/block/virtio_blk.c: Convert to use disk_set_capacity
> drivers/block/xen-blkfront.c: Convert to use disk_set_capacity
> drivers/nvme/host/core.c: Convert to use disk_set_capacity
> drivers/scsi/sd.c: Convert to use disk_set_capacity
>
> block/genhd.c | 19 +++++++++++++++++++
> drivers/block/virtio_blk.c | 4 +---
> drivers/block/xen-blkfront.c | 5 +----
> drivers/nvme/host/core.c | 2 +-
> drivers/scsi/sd.c | 2 +-
> include/linux/genhd.h | 1 +
> 6 files changed, 24 insertions(+), 9 deletions(-)
>

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