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SubjectRe: [PATCH] loop: cleanup partitions when detaching loop device
On Sun,  3 Mar 2013 13:49:13 -0500 Phillip Susi <psusi@ubuntu.com> wrote:

> Any partitions added by user space to the loop device were being
> left in place after detaching the loop device. This was because
> the detach path issued a BLKRRPART to clean up partitions if
> LO_FLAGS_PARTSCAN was set, meaning that the partitions were auto
> scanned on attach. Replace this BLKRRPART with code that
> unconditionally cleans up partitions on detach instead.

huh. What is the user-visible effect of this bug? Just a memory leak
or something more serious?

If "something more serious", why did this problem remain hidden for so
long?

> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -1039,12 +1039,24 @@ static int loop_clr_fd(struct loop_device *lo)
> lo->lo_state = Lo_unbound;
> /* This is safe: open() is still holding a reference. */
> module_put(THIS_MODULE);
> - if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev)
> - ioctl_by_bdev(bdev, BLKRRPART, 0);
> lo->lo_flags = 0;
> if (!part_shift)
> lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
> mutex_unlock(&lo->lo_ctl_mutex);
> + if (bdev)
> + {

scripts/checkpatch.pl is your friend.

Can you please suggest a code comment which we can slip in here to tell
readers what's going on and why we're doing this?

> + struct disk_part_iter piter;
> + struct hd_struct *part;
> +
> + mutex_lock_nested(&bdev->bd_mutex, 1);
> + invalidate_partition(bdev->bd_disk, 0);
> + disk_part_iter_init(&piter, bdev->bd_disk, DISK_PITER_INCL_EMPTY);
> + while ((part = disk_part_iter_next(&piter)))
> + delete_partition(bdev->bd_disk, part->partno);
> + disk_part_iter_exit(&piter);
> + mutex_unlock(&bdev->bd_mutex);
> + }



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