Write Same can return an error asynchronously if it turns out the
underlying SCSI device does not support Write Same, which makes a
proper fallback to other methods in __blkdev_issue_zeroout impossible.
Thus only issue a Write Same from blkdev_issue_zeroout an don't try it
at all from __blkdev_issue_zeroout as a non-invasive workaround.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reported-by: NJunichi Nomura <j-nomura@ce.jp.nec.com>
Fixes: e73c23ff ("block: add async variant of blkdev_issue_zeroout")
Tested-by: NJunichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: NJens Axboe <axboe@fb.com>