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SubjectRe: [PATCH] loop: prevent bdev freeing while device in use
On Mon, Apr 01, 2013 at 04:58:05AM -0700, Anatol Pomozov wrote:
> lo->lo_flags |= LO_FLAGS_PARTSCAN;
> if (lo->lo_flags & LO_FLAGS_PARTSCAN)
> ioctl_by_bdev(bdev, BLKRRPART, 0);
> +
> + /* bdev lifecycle is defined by its bd_inode (see
> + * struct bdev_inode usage). In case of loop device we need to make
> + * sure that bdev deallocation will not happen between loop_set_fd()
> + * and loop_clr_fd() invocations. To do this we need to hold
> + * bdev inode here and put it later in loop_clr_fd().
> + */
> + ihold(bdev->bd_inode);

That's open-coded bdgrab()

> + if (bdev) {
> + BUG_ON(atomic_read(&bdev->bd_inode->i_count) < 2);
> + iput(bdev->bd_inode);

... and that - bdput() (I'd drop that BUG_ON())


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