Messages in this thread | | | Subject | Re: [PATCH -next RFC 2/3] block: factor out the setting of GD_NEED_PART_SCAN | From | Yu Kuai <> | Date | Mon, 13 Feb 2023 10:41:32 +0800 |
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Hi,
在 2023/02/12 19:36, Hannes Reinecke 写道: > On 2/12/23 10:26, Yu Kuai wrote: >> From: Yu Kuai <yukuai3@huawei.com> >> >> In order to prevent scan partition for a device that is opened >> exclusively by someone else, new conditions will be added to >> disk_scan_partitions() in the next patch. Hence if device is opened >> exclusively between bdev_add() and disk_scan_partitions(), the first >> partition scan will fail unexpected. This patch factor out the setting >> of GD_NEED_PART_SCAN to prevent the problem. >> >> Signed-off-by: Yu Kuai <yukuai3@huawei.com> >> --- >> block/genhd.c | 2 +- >> block/ioctl.c | 1 + >> 2 files changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/block/genhd.c b/block/genhd.c >> index 075d8da284f5..c0d1220bd798 100644 >> --- a/block/genhd.c >> +++ b/block/genhd.c >> @@ -367,7 +367,6 @@ int disk_scan_partitions(struct gendisk *disk, >> fmode_t mode) >> if (disk->open_partitions) >> return -EBUSY; >> - set_bit(GD_NEED_PART_SCAN, &disk->state); >> bdev = blkdev_get_by_dev(disk_devt(disk), mode, NULL); >> if (IS_ERR(bdev)) >> return PTR_ERR(bdev); >> @@ -493,6 +492,7 @@ int __must_check device_add_disk(struct device >> *parent, struct gendisk *disk, >> if (ret) >> goto out_unregister_bdi; >> + set_bit(GD_NEED_PART_SCAN, &disk->state); >> bdev_add(disk->part0, ddev->devt); >> if (get_capacity(disk)) >> disk_scan_partitions(disk, FMODE_READ); > Usual caveat: > What happens if the flag is already set here? > Wouldn't that imply that another scan is underway?
I think this is not true, currently set the state just means we're going to scan, and if some checking failed, the state will be left. I don't have a good idea how to fix this yet...
Thanks, Kuai
> And wouldn't it be better to use 'test_and_set()'? > > >> diff --git a/block/ioctl.c b/block/ioctl.c >> index 6dd49d877584..0eefcdb936a0 100644 >> --- a/block/ioctl.c >> +++ b/block/ioctl.c >> @@ -528,6 +528,7 @@ static int blkdev_common_ioctl(struct block_device >> *bdev, fmode_t mode, >> return -EACCES; >> if (bdev_is_partition(bdev)) >> return -EINVAL; >> + set_bit(GD_NEED_PART_SCAN, &bdev->bd_disk->state); >> return disk_scan_partitions(bdev->bd_disk, mode & ~FMODE_EXCL); >> case BLKTRACESTART: >> case BLKTRACESTOP: > Similar here. > > Cheers, > > Hannes
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