When a storage device rejects a WRITE SAME command we will disable write
same functionality for the device and return -EREMOTEIO to the block
layer. -EREMOTEIO will in turn prevent DM from retrying the I/O and/or
failing the path.

Yiwen Jiang discovered a small race where WRITE SAME requests issued
simultaneously would cause -EIO to be returned. This happened because
any requests being prepared after WRITE SAME had been disabled for the
device caused us to return BLKPREP_KILL. The latter caused the block
layer to return -EIO upon completion.

To overcome this we introduce BLKPREP_INVALID which indicates that this
is an invalid request for the device. blk_peek_request() is modified to
return -EREMOTEIO in that case.
Reported-by: NYiwen Jiang <jiangyiwen@huawei.com>
Suggested-by: NMike Snitzer <snitzer@redhat.com>
Reviewed-by: NHannes Reinicke <hare@suse.de>
Reviewed-by: NEwan Milne <emilne@redhat.com>
Reviewed-by: NYiwen Jiang <jiangyiwen@huawei.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>