Re: [PATCH 2/7] block: merge invalidate_partitions into rescan_partitions

Eric Biggers
2019-11-30T22:06:43Z

On Sat, Nov 30, 2019 at 01:49:42PM -0800, Eric Biggers wrote:
> Hi Christoph,
>
> On Thu, Nov 14, 2019 at 03:34:33PM +0100, Christoph Hellwig wrote:
> > A lot of the logic in invalidate_partitions and rescan_partitions is
> > shared. Merge the two functions to simplify things. There is a small
> > behavior change in that we now send the kevent change notice also if we
> > were not invalidating but no partitions were found, which seems like
> > the right thing to do.
> >
> > Signed-off-by: Christoph Hellwig <hch@lst.de>
> > Reviewed-by: Jan Kara <jack@suse.cz>
> > ---
> > block/ioctl.c | 2 +-
> > block/partition-generic.c | 38 ++++++++++++++------------------------
> > fs/block_dev.c | 5 +----
> > include/linux/genhd.h | 4 ++--
> > 4 files changed, 18 insertions(+), 31 deletions(-)
> >
>
> Mainline is broken for me because systemd-udevd spins forever using max CPU
> starting at boot time. I bisected it to this commit.
>
> I'm not an expert in this code, but the following patch fixes it:
>
> diff --git a/block/partition-generic.c b/block/partition-generic.c
> index 6b9f4f5d993a..b0eebd7580ab 100644
> --- a/block/partition-generic.c
> +++ b/block/partition-generic.c
> @@ -599,7 +599,8 @@ int rescan_partitions(struct gendisk *disk, struct block_device *bdev,
> * Tell userspace that the media / partition table may have
> * changed.
> */
> - kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);
> + if (invalidate)
> + kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);
> return 0;
> }
>
>
> Do you have any better suggestion, or should I just send this as a formal patch?
>

Actually this code was moved around more between the bad commit and mainline,
so the fix for mainline would be:

diff --git a/fs/block_dev.c b/fs/block_dev.c
index ee63c2732fa2..69bf2fb6f7cd 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1531,7 +1531,7 @@ int bdev_disk_changed(struct block_device *bdev, bool invalidate)
ret = blk_add_partitions(disk, bdev);
if (ret == -EAGAIN)
goto rescan;
- } else {
+ } else if (invalidate) {
/*
* Tell userspace that the media / partition table may have
* changed.