RFC: untangle and fix __blkdev_issue_discard

[Keith Busch]

On Thu, Mar 07, 2024 at 08:11:47AM -0700, Christoph Hellwig wrote:
> this tries to address the block for-next oops Chandan reported on XFS.
> I can't actually reproduce it unfortunately, but this series should
> sort it out by movign the fatal_signal_pending check out of all but
> the ioctl path.

The last patch moves fatal_signal_pending check to blkdev_issue_discard
path, which has a more users than just the ioctl path.