dm mpath: retry BLK_STS_RESOURCE errors

Retry requests instead of failing them if an out-of-memory error occurs
or the block driver below dm-mpath is busy. This restores the v4.12
behavior of noretry_error(), namely that -ENOMEM results in a retry.

Fixes: 2a842acab109 ("block: introduce new block status code type")
Signed-off-by: Bart Van Assche <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
Signed-off-by: Mike Snitzer <[e-mail]>

drivers/md/dm-mpath.c

···
 	case BLK_STS_TARGET:
 	case BLK_STS_NEXUS:
 	case BLK_STS_MEDIUM:
-	case BLK_STS_RESOURCE:
 		return 1;
 	}