scsi: target: Add atomic support to target_core_iblock

Make target_core_iblock use the LIO helper function to translate its
block_device atomic settings to LIO settings. If we then get a write
that LIO has indicated is atomic via the SCF_ATOMIC flag, we use the
REQ_ATOMIC flag to tell the block layer to perform an atomic write.

Signed-off-by: Mike Christie <[e-mail]>
Signed-off-by: John Garry <[e-mail]>
Reviewed-by: John Garry <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/target/target_core_iblock.c

···
 	if (bdev_nonrot(bd))
 		dev->dev_attrib.is_nonrot = 1;
 
+	target_configure_write_atomic_from_bdev(&dev->dev_attrib, bd);
+
 	bi = bdev_get_integrity(bd);
 	if (!bi)
 		return 0;
···
 			else if (!bdev_write_cache(ib_dev->ibd_bd))
 				opf |= REQ_FUA;
 		}
+
+		if (cmd->se_cmd_flags & SCF_ATOMIC)
+			opf |= REQ_ATOMIC;
 	} else {
 		opf = REQ_OP_READ;
 		miter_dir = SG_MITER_FROM_SG;