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SubjectRe: [PATCH] loop: prevent bdev freeing while device in use
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Hi

On Mon, Apr 1, 2013 at 9:28 AM, Al Viro <viro@zeniv.linux.org.uk> wrote:
> 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()

Done. It also requires EXPORTING bdgrab.

The test still passes.

>
>> + 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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